tuents such as ozone, sulphur dioxide and nitric acid. However for ...... + 1). 2.2 x 10"_z (T/300)l. + I. 0.27. 1.0. 0.76. IUPAC. (1989). C2H'5. 2,0x10-2_. (T/300)-( ...
KIN_
WORLDMETEOROLOGICALORGANIZATION GLOBAL OZONERESEARCHAND MONITORINGPROJECT-REPORT NO.20
Scientific Assessment of Stratospheric Ozone: 1989
Volume Appendix:
NATIONAL
AERONAUTICS
II
AFEAS
Report
AND SPACE
ADMINISTRATION
UNITED KINGDOM - DEPARTMENT OF THE ENVIRONMENT NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
ALTERNATIVE
UNITED
NATIONS
WORLD
METEOROLOGICAL
FLUOROCARBON
ENVIRONMENT
ENVIRONMENTAL
PROGRAM
ORGANIZATION ACCEPTABILITY
STUDY
(AFEAS)
TABLE Io
Igo
INTRODUCTION Introduction PHYSICAL
..........................................................
Executive
Summary .................................................... Properties
of Alternatives
Chlorofluorocarbons REACTION Executive
Summary
Rate Constants for Selected
ABSORPTION
CROSS
Executive
Summary of Ultraviolet
Fluorocarbons We
TROPOSPHERIC Combined
and Recommended
Rate Constants
Tables ...............
and S. P. Sander .................
47
SECTIONS .................................................. Absorption
107
Cross Sections
of a Series of Alternative
by M. J. Molina ...................................... OH AND HCFC/HFC
Summary
41
HCFC's and HFC's with OH and
M. J. Kurylo
111
LIFETIMES
and Conclusions
...................................
123
Atmospheric Lifetimes for HCFCs Table .............................. The Tropospheric Lifetime_ of Halocarbons and their Reactions with OH Radicals: An Assessment Based on the Concentration of t4CO
124
by R. G. Derwent and A. Volz-Thomas ............................... Tropospheric Hydroxyl Concentrations and the Lifetimes of
127
Hydrochlorofluorocarbons Vlo
11
RATE CONSTANTS
Evaluated
Review
7
to the Fully Halogenated
by M. O. McLinden ...............................
O(mD) by R. F. Hampson, IVe
3
PROPERTIES
Physical
III.
OF CONTENTS
DEGRADATION Combined
(HCFCs)
by M. J. Prather ....................
149
...................................
161
MECHANISMS Summary
Fluorine-Containing
and Conclusions
Products in Atmospheric
Degradation
Table ...........
Tropospheric Reactions of the Haloalkyl Radicals Formed from Radical Reaction with a Series of Alternative Fluorocarbons by R. Atkinson ....................................................
165
Degradation Mechanisms of Selected Hydrochlorofluorocarbons in the Atmosphere: An Assessment of Current Knowledge by R. A. Cox and R. Lesclaux ................................................... An Assessment Reactions by
of Potential of Alternative
Degradation
Products
Fluorocarbons
Degradation
Chlorofluorocarbons
Mechanisms
in the Troposphere 235
of Hydrogen
(HCFC) and Fluorocarbons
Containing (HFC)
by R. Zellner .....................................................
251
iii
I_ECEDING
209
in the Gas-Phase
H. Niki .......................................................
Atmospheric
162
Hydroxyl
PAGE BLANK
NOT
FILMED
VII.
LIQUID
PHASE
Executive
PROCESSES
Summary ..................................................
269
Possible Atmospheric Lifetimes and Chemical Reaction Mechanisms for Selected HCFCs, HFCs, CH3CCI3, and their Degradation Products Against
Dissolution
andor
Degradation
in Seawater
and Cloudwater
by P. H. Wine and W. L. Chameides ................................. VIII.
OZONE
DEPLETION
Executive
POTENTIALS
Summary
Relative
Effects
273
..................................................
on Stratospheric
Ozone
299
of Halogenated
Methanes
and
Ethanes of Social and Industrial Interest by D. A. Fisher, C. H. Hales, Filkin, M. K. W. Ko, N. D. Sze, P. S. Connell, D. J. Wuebbles, I. S. A. Isaksen, IXg
HALOCARBON Executive Relative
and F. Stordal ......................................
GLOBAL Summary
Effects
WARMING
303
POTENTIALS
..................................................
on Global
Warming
381
of Halogenated
Methanes
and Ethanes
of Social and Industrial Interest by D. A. Fisher, and C. H. Hales, Wang, M. K. W. Ko and N. D. Sze .................................. Xo
IMPACT OZONE
ON PHOTOCHEMICAL
Executive
Tropospheric XI.
NATURAL
OXIDANTS
INCLUDING
TROPOSPHERIC
of Potential
Impact
of Alternative
405 Fluorocarbons
on
Ozone by H. Niki ......................................
409
SOURCES
Executive
Summary ..................................................
Natural Chlorine and Fluorine in the Atmosphere, by J. P. Friend .................................................... XII.
Wei-Chyung 383
Summary ..................................................
An Assessment
D. L.
BIOLOGICAL
AND HEALTH
Combined
Summary
Toxicology
of Atmospheric
Water and Precipitation 433
EFFECTS
and Conclusions
Hydrochlorofluorocarbons
429
...................................
Degradation
Products
by L. S. Kaminsky
451
of Selected ..........................
Assessment of Effects on Vegetation of Degradation Products from Alternative Fluorocarbons by D. C. McCune and L. H. Weinstein
455 .........
463
ANNEXES: A. Experts
and Reviewers
B. Companies C. Statement REFERENCES
Sponsoring
................................................
A- 1
AFEAS .........................................
B- 1
of Work ...................................................
.................................................................
C-1 R- 1
iv
I.
INTRODUCTION
Introduction
INTRODUCTION This report is the outcome of the Alternative AFEAS
was organized
geted to replace
to evaluate
Fluorocarbon
the potential
fully halogenated
Environmental
chlorofluorocarbons
(CFCs).
of the compounds
to affect stratospheric
• their potential
to affect tropospheric
• their potential
to contribute
• the atmospheric hence, • the potential The alternative
mechanisms
environmental compounds
effects
carbon
tar-
was to:
the environmental
acceptability
of the
ozone,
global
warming,
of the compounds,
of the decomposition
in order to identify
and hydrogen
chlorine
and
(HFCs) with one or two carbon atoms
and hydrochlorofluorocarbons
atoms and one or more each of fluorine,
their products
products.
to be studied were hydrofluorocarborns
and one or more each of fluorine
compounds
ozone,
to model calculated
degradation
Study (AFEAS).
of alternative
The objective
Evaluate all relevant current scientific information to determine alternative fluorocarbons with special emphasis on: • the potential
Acceptability
effects on the environment
and hydrogen.
(HCFCs) Because
with one or two
they contain
hydrogen
atoms, HFCs and HCFCs are less stable in the atmosphere than CFCs and thus have greatly reduced ozone depletion potentials. Additionally, HFCs do not contain chlorine atoms which are the key factor in ozone depletion.
All compounds
placed on evaluating
meeting
the above criteria
HCFC
123
CCI2HCF3
HCFC
141b
CC12FCH3
HCFC
142b
CCIF2CH3
HCFC
22
CCIF2H
HCFC 124 HFC 134a
CCIFHCF3 CF3CFH2
HFC
152a
CF2HCH3
HFC
125
CF3CF2H
The 52 scientists nex A. Experts global warming
worldwide
prepared
or more scientists.
were evaluated
where data exists but emphasis
who were involved
review papers
In addition,
potentials.
in AFEAS
on all aspects
model calculations
A meeting
are listed in at the end of this report in An-
of the topic and each paper was reviewed
were carried
was held in Boulder,
ship of Dr. R. T. Watson of the National
Aeronautics
out on ozone depletion
Colorado
AFEAS mental
was conducted from around
acceptability
by independent
scientists
but was organized
the world as part of cooperative
of CFC alternatives.
Companies
industry
(NASA)
and sponsored
participating
PAGE BLANK
for experts
and
of that meeting.
by fifteen
CFC
efforts to study the safety and environin AFEAS
3 PRECEDING
by one
and halocarbon
in May 1989 under the chairman-
and Space Administration
reviewers to discuss and reach a consensus. The papers in this report are the outcome Summaries of these papers form part of the August 1989 UNEP Science Assessment.
producers
was
the following.
NOT
FILMED
are listed in Annex
B.
INTRODUCTION The statement
of work used to initiate this project
This report consists of reviewers'
opinions
of the individual and discussion.
and the work assignments
papers prepared They are arranged
there is more than one paper on a topic, a combined the papers in that section.
for the Boulder in sections
summary
4
are given in Annex
meeting,
according
and conclusions
C.
revised to take account to subject matter.
was prepared
Where
to introduce
II.
Physical
Properties
PHYSICAL
of Alternatives
Mark
PROPERTIES
to the Fully
Institute Boulder,
Chlorofluorocarbons
O. McLinden
Thermophysics National
Halogenated
Division
of Standards Colorado
and Technology 80303
PHYSICAL PROPERTIES EXECUTIVE This report is concerned rofluorcarbons
(CFCs)
with physical
SUMMARY
properties
used as refrigerants,
are the fixed points of the fluids (triple
of possible
solvents,
alternatives
and foam blowing
point and boiling
to the fully halogenated agents.
point temperatures,
Specifically and critical
chlo-
considered temperature,
pressure, and density), vapor pressure, saturated liquid density, solubility in water, and hydrolysis rates. These properties directly or indirectly influence the fate of a chemical in the environment and also include the key thermophysical
data necessary
containing
methanes
R123,
halogenated
R141b,
to estimate
and ethanes.
other properties.
Included
are R125,
The fluids considered
are hydrogen-
R22, R134a,
R124,
R152a,
R142b,
and methyl chloroform.
A wide variety of data sources have been considered
including
published data, surveys and compilations
of properties, and unpublished data provided by several of the companies which are members of the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS) consortium. These data have been compiled and evaluated. Recommended values are tabulated for the fluid fixed points. The temperature dependencies of vapor pressure, saturated liquid density and solubility in pure water are presented lations and as a tabulation of values calculated from these correlations. The data vary greatly in quality and reliability,
and are sometimes
conflicting.
in terms of corre-
At least limited data were
available for the fixed points, vapor pressure and liquid density of all of the compounds. The values presented here are felt to be reasonable, although the lack of documentation in many cases makes an objective assessment of accuracy impossible, Identified
and revisions will certainly be necessary as additional data become available.
as high priority needs are improved
and improved
liquid density
For solubility
vapor pressure data for R 124, R142b, and, especially,
data for R142b.
in water, the data were much more limited.
able only for R22. For the other fluids,
unpublished
used; again, while these data may be reliable, bility information trapolating extremely
R141b,
was correlated
in terms
Published,
data provided
an assessment
of the Henry's
fully documented
by the chemical
of their accuracy law constant.
data were avail-
manufacturers
was not possible.
The use of Henry's
were
The solulaw in ex-
from the saturation vapor pressure conditions employed in most of the measurements to the low partial pressures that can be expected in the atmosphere is a source of uncertainty. For
solubility in salt water, only data for R22 and methyl chloroform were found; an empirical 'salting parameter' evaluated from data for these two fluids can be applied to the other fluids in the absence of data. Finally,
hydrolysis
decomposition
is considered.
of a compound
Hydrolysis
dissolved
represents
in the oceans
were quite sparse; except for R22 and methyl chloroform, In view of the very limited solubilities of these compounds, that can be estimated
or extrapolated
lution in water and subsequent
from the available
hydrolysis
one possible
mechanism
or in cloud water.
rates
recommended values could not be developed. even the order of magnitude-type information
data may be sufficient
is a significant
for the environmental
The data for hydrolysis
destruction
to determine
mechanism
whether
disso-
for these compounds.
Thus, complete data on solubility and hydrolysis may be needed only for methyl chloroform. This point is considered in detail in a study by Wine and Chameides presented elsewhere in this volume.
7 PRECEDING
PAGE BLALIK
NOT
FILM'ED
N92-15436
PHYSICAL
PROPERTIES
FULLY HALOGENATED
OF ALTERNATIVES
TO THE
CHLOROFLUOROCARBONS
Mark O. McLinden Thermophysics National
Institute
Division
of Standards
Boulder,
Colorado
and Technology 80303
PRECEDff'_G
PAGE
BLAD,_LKNOT
FILMED
PHYSICAL PROPERTIES 1. INTRODUCTION The physical
properties
of a fluid largely
determine
its suitability
present study is concerned
with properties
bons, a class of compounds
widely used as working fuids
equipment,
as solvents
and foam blowing
ples, the thermophysical and viscosity
properties
are necessary
conductivity
agents,
considered
environmental
of a fluid in refrigeration
agent has a large effect on the insulating
The
chlorofluorcar-
and air-conditioning As exam-
(PVT)
equipment.
behavior,
The thermal
value of a foam. The normal boiling
for solvent uses.
focuses on those properties point parameters),
in refrigeration
the pressure-volume-temperature
the performance
This paper, as part of the larger Alternative Specifically
to the fully halogenated
(refrigerants)
and in a wide variety of other applications.
such as enthalpy,
to predict
of the blowing
point is important
of possible alternatives
for use in a given application.
Fluorocarbon
that influence the environmental
acceptability
are the fluid fixed point parameters
vapor pressure,
implications
saturated
Environmental
of alternative
Study (AFEAS),
fluorocarbon
fluids.
(triple point, normal boiling point, and critical
liquid density,
of the first five properties
Assessment
solubility
in water, and hydrolysis
listed are indirect.
These properties
rates. The
are, however,
often required as inputs for various models and estimation techniques. The last two properties can directly affect the fate of a fluorocarbon once it is emitted to the environment. One possible mechanism for the removal
of a fluorocarbon
clouds and subsequent ic data associated ism is assessed
from the environment
reaction
The fluids to be considered
literature
to replace
compilations by several
over information
the fully halogenated
halogenated
thus, all possible
sources
such as that by the Japanese chemical
manufacturers
produced
methanes
and
seen with
given to published
Association
presented
graphically
of Refrigeration of the AFEAS
sources
or in terms of a correlation.
and, as will be seen, are sometimes
These include
and surveys such as that by Stewart,
which are members
over unpublished
and as a consequence,
of data have been utilized.
Abstracts
work in progress at the National Institute of Standards and Technology is generally
the bas-
of this mechan-
fluids is similar to the range
here have never been commercially
(as revealed by a search of Chemical
data provided
reliability
This paper addresses the effectiveness
in
compounds.
et al. (1981)),
preference
candidates
boiling points for these candidate
the data for many of them are sparse;
experimental
or in water droplets
(1989).
in this report are the leading
In many cases, the fluids considered the published
in the environment;
and R11 (CC13F). All are hydrogen-containing
The range of normal
the fully halogenated
in the ocean
with water (hydrolysis).
of decomposition
by Wine and Chameides
CFCs such as R12 (CClzFz) ethanes.
of the fluorocarbon
with this mechanism
is its dissolution
(1975),
unpublished
group, and, finally,
(NIST). Where available,
and to actual experimental
The data differ greatly
values
in quality and
conflicting.
To be of maximum and immediate utility to the other AFEAS groups which may need to make use of this information, all data are fit with standard forms and presented primarily in terms of the resulting correlations. In this report a summary section containing a detailed discussion of the data themselves.
coefficients
to the correlations,
11
RE-CEDING
PAGE
BI.AE_IK NOT
F_LMI_D
etc. precedes
PHYSICAL PROPERTIES 2. SUMMARY Fluid Fixed Points The triple point, normal
boiling point, and critical point parameters
are fundamental
characteristics
of
a fluid. The triple point is the state at which three phases (solid, liquid and vapor) coexist; it is virtually identical with the more often reported freezing point. The normal boiling point is simply the temperature at which the vapor pressure of a fluid is one standard atmosphere (101.325 kPa). Since the vapor pressures of nearly all fluids are approximately parallel when plotted as the logarithm of pressure versus inverse temperature, the normal boiling point is a rough predictor of the vapor pressure at all temperatures. The critical point is the state at which the properties of the saturated liquid and vapor become indistinguishable;
coexisting
liquid and vapor are possible
only at temperatures
and pressures
below the critical
point values. These parameters, many different
often in the absence of any other information,
compounds
are frequently
to select a more limited set for further study.
used in screening among
For many applications
they de-
fine the temperature limits for the use of a particular fluid. Clearly a solvent or refrigerant cannot be used below the triple point temperature. For many refrigeration applications, operation at sub-atmospheric pressures is avoided and, thus, the normal boiling point is a more practical lower limit. Vapor compression refrigeration
equipment
transports
heat through
condensation
and evaporation
(i.e. two-phase)
processes
and thus the critical point represents an upper temperature and pressure limit. The critical point parameters are the essential inputs to estimation techniques based on the law of corresponding states, which is the observation
that, when scaled by the critical
parameters,
The triple point, normal boiling point, and critical
the properties
point parameters
of nearly all fluids are similar.
are given in Table 1. (In this table,
and all subsequent tables, the fluids are listed in order of increasing normal boiling The selection of these values is discussed in detail in the Discussion section.
Vapor
point temperature.)
Pressure
The experimental a form suggested
vapor pressure by Goodwin
data were fit to the following
& Haynes
In p = at/T where p is pressure, asymptotic
critical
T is absolute behavior
which
is a modification
of
(1982): + a2 + a3T +
temperature
(kelvins)
was empirically
range for R134a and R123 (Weber
1989). The coefficients
a4(l-
T/Tc)1"5
(1)
and T c is the critical
predict a value of approximately
tion (1); a value of 1.5, however, the temperature
equation,
temperature.
1.9 for the exponent
found to yield a better
for
in the last term in Equa-
fit over a wide temperature
for each of the fluids considered,
range of the data, are given in Table 2. Modest
Theories
extrapolations
along with
outside this range should
yield fairly accurate results. This table also gives the RMS deviations between Equation (1) and the input data. These RMS values serve as indications of the precision of the data and the agreement between different sources.
Particularly
for those fluids with only one data source, the method of computing
tions cannot detect any systematic
errors
in the data, and thus RMS values 12
provide
RMS devia-
little information
on
PHYSICAL PROPERTIES the accuracy of the data and the resulting correlation. In most cases the accuracy of the correlation cannot be stated because of insufficient documentation; this is considered in more detail in the Discussion section. The vapor pressures
as functions
of temperature
are also tabulated
along with the other properties
in the Appendix.
Saturated
Liquid Density
Liquid densities
along the saturation
line, Q, were fit to the commonly
O/Oc = 1 + dlr0 where r = (1 - T/T c and 0c is the critical
used form:
+ d2"r2/3 + d3r + d4v4/3
density.
The critical
(2)
exponent,/3,
is properly
evaluated
from
experimental measurements near the critical point. For most of the fluids considered here a value of 1/3 is assumed because of the lack of data. Equation (2) is well-grounded in theory, has the proper form over a wide range of temperature of saturated
liquid densities.
vapor pressure, perature
the vicinity of the critical point, and is often used in the correlation
The fit of density data to Equation
the temperature
and density
Solubility
including
required
(2) is summarized
range of the data and the RMS deviation in Equation
(2) may be found
in Table
in Table 3. As with
are also given. The critical
tem-
1.
in Water
The fluids considered typical ambient
in this report are all highly volatile
temperatures)
and thus their presence
(most have normal boiling points well below
in the environment
will be predominantly
as trace
gases in the atmosphere. Atmospheric gases will, however, dissolve to some extent into the oceans and into water droplets in clouds. The magnitude of this solubility will influence the importance of hydrolysis as a degradation
mechanism.
The dissolution
of trace gases into water is well-represented Xa
which states that the concentration tial pressure
of substance
approaching
zero but in practice
"a"
of substance
"a"
dissolved
in a solvent,
Pa" Henry's
Xa, is proportional
to the par-
law strictly applies only in the limit of xa
holds very well for gas partial
even higher for gases of low solubility
law: (3)
Pa/Ha
=
over the solution,
by Henry's
pressures
(such as the fluorocarbons).
up to a few hundred
The proportionality
kPa and
factor in Equation
is called the Henry's law constant. The units of H a are pressure divided by a concentration (e.g. kPa/mass % or atm/ppm). The Henry's law constant is not constant but is a function of temperature which (3),
H a,
can be well represented
by: In (1/Ha)
= ht + hz/(T
+
(4)
h3)
Solubility data have been used to evaluate the coefficients in Equation 4; they are given in Table 4. Note that the term h3 is used only for R22. Equation 4 has been used to calculate solubilities in water at the commonly
referenced
conditions
of 298.15
K (25°C) and a fluorocarbon
partial
pressure
of one
standard atmosphere. (While this is an unrealistically large partial pressure for gases in the environment, it is useful for comparisons between compounds.) For several of the fluids there was considerable disagreement
(as much as a factor of two) in measured
by comments
solubility
in Table 4. 13
from different
sources;
these are flagged
PHYSICAL PROPERTIES At least limited
solubility
pounds considered
data were obtained
as part of AFEAS.
not exist, the method of Irmann solubilities pressure
of the halogenated at 298.15
(mostly
from unpublished
sources)
For other fluids which may be of interest
(1965) (as reported
hydrocarbons.
by Lyman,
et al. 1982) can be used to estimate
This method requires
K (25°C) of the compound
in question
for all of the com-
and for which data may
only the molecular
and yields the solubility
structure
the
and vapor
in water at 298.15
K.
The results of applying this estimation technique to the nine compounds considered here are given in Table 5. For most of the fluids the agreement is very good (within 15 %), validating this method. The estimated values for R 125 and R 14 l b, however, values. In view of the good agreement values
for R125 and certainly
for the other fluids, this discrepancy
from the reported
casts some doubt on the reported
for R141b.
The above results are for solubilities ed by the following
differ by factors of two and five, respectively
form reported
in pure water. The solubilities
by Lyman, In
in saline solutions
can be represent-
et al. (1982):
(Xa/Xa,s)
--
(5)
KsC s
x a is the solubility in pure water and Xa, s is the solubility in a saline solution of concentration C s. The term Ks is an empirical salting parameter. Values of K s are positive, so solubilities in salt water are where
lower than those in pure water. methyl chloroform.
Zhang,
For the compounds
of interest
et al. (1985) report R22 solubilities
here, data were found only for R22 and in sodium chloride
solutions
over the tem-
perature range 283-323 K. Their data confirm Equation (5) and can be used to compute values of K s ranging from 0.0060 L/g at 283 K to 0.0082 L/g at 333 K. These correspond to solubilities in sea water which are 81-75%
of those in pure water.
for methyl chloroform Limited
corresponding
data for the solubility
Walraevens,
et al. (1974) report a salting parameter
to a solubility
in sea water
of other fluorocarbons
(CHCI2F) (Downing 1988) and R114 (CCIF2CC1F2) 0.0061 and 0.029 L/g respectively; these correspond
which
with other classes
and methyl chloroform fully halogenated
R114.
of fluids (Lyman,
are better analogues
in salt solutions
were also found.
et al. 1982). The polar,
to the full set of fluids considered
The effect of salt on the solubilities
for the other fluids in the absence
Data for R21
is similar to those
hydrogen-containing
of data. This corresponds
R22, R21,
here than the weakly polar,
of the fluids considered
in this report
thus, probably closer to those observed with R22 and R21 than with R114. Considering of salting parameters for R22, R21, and methyl chloroform, a salting parameter of 0.007 mended
L/g
(Stepakoff and Modica 1973) give values of Ks of to solubilities in sea water which are 81 and 36%
of those in pure water. This range for the ratio of sea water to pure water solubilities observed
of 0.0073
is 78% of that in pure water.
to a solubility
is,
the similarity L/g is recom-
in sea water which
is 78% of that in pure water.
Hydrolysis Hydrolysis
Rates refers to the reaction of a compound
isms are possible fluorocarbon
(Ellenrieder
reacts
and Reinhard
with water or the hydroxide R-C-R'X
in aqueous solution. For the fluorocarbons,
1988). In nucleophilic
+ H20/OH-
ion (OH-) _ 14
substitution,
to form an alcohol
R-C-R'OH
+ HX
two mechan-
or hydrolysis
proper,
the
plus an acid: (6)
PHYSICAL PROPERTIES where X represents a halogen (F or CI) and R and R' are nonreacting groups. In the second mechanism, known as elimination or dehydrohalogenation, water or hydroxide catalyzes the reaction to form an alkene plus acid: R-CH-CR'X
+ HzO/OH-_
RC=CR'
+ H20/OH-
(7)
+ HX
In this work, the term "hydrolysis" will refer to the general reaction in aqueous solution; the terms "substitution" and "elimination" will be used when it is necessary to distinguish between the different mechanisms.
A single-carbon
Other mechanisms here.
compound
(such as R22) can obviously
occur for the fully halogenated
The elimination
increases (reaction
with hydroxyl).
more important
process.
1988) but will not be considered
in the molecule
(Mabey
becomes
undergo only the substitution
(Downing
(Vogel, et al. 1987). Either process may be neutral (reaction primarily with water) or base-promoted primarily
process
compounds
A third possibility,
as the number of halogens
acid promotion
by the hydronium
ion, H +, does not occur
and Mill 1978).
The rate of reaction, fluorocarbon
expressed
concentration.
rates. For base-promoted
in terms
of the disappearance
Thus the solubility processes,
the reaction
case of base-promoted
can be expressed
and neutral
process
is proportional
will have an influence
rate is also proportional
which in turn is related to the pH. Where the neutral For the general
of fluorocarbon,
of the compound
dominates,
processes
occurring
= [RX](kB[OH-]
+ k N)
to the hydroxyl
concentration,
the rate is independent simultaneously,
where square brackets
denote a concentration
in moles/liter,
the reaction
of the rate constants
are functions
of temperature,
typically
expressed
fluorocarbon,
and kB and
respectively. Both kB and kN may and elimination mechanisms. Each in terms of an Arrhenius
expression:
k = A exp(-E/RT) E is the activation
energy
of a fluorocarbon
isms. To fully describe To further complicate
of the reaction
is thus seen to be a rather complex process with several possible mechan-
the temperature the situation,
1988 gives information
and pH dependence
dependence
of a reaction
metals can catalyze hydrolysis
and pH dependence
= k[R22][OH-]
of k is given by Equation
15
requires
(9) with:
up to eight parameters.
and increase reaction
located for the hydrolysis
on both the temperature -d[R22]/dt
The temperature
(9)
and R is the gas constant.
of magnitude or more (Downing 1988). The information bons considered here was limited. Downing
rate
(8)
RX is the reacting
k N are the rate constants for the base-promoted and neutral processes, be further broken down into additive contributions from the substitution
The hydrolysis
of pH.
as: -d[RX]/dt
where
to the
on its reaction
rates by an order
rates of the fluorocar-
of R22 hydrolysis
rates: (10)
PHYSICAL PROPERTIES A = 1.87 x 108 L/(mol's) -E/R One must infer from Equation together
(10) that either the neutral
into a single rate constant
At a temperature
= -7692.
or that the former
of 298 K and a concentration
K
and base-promoted process
of hydroxide
processes
is insignificant,
have been lumped
i.e. kN is small.
of 1 x 10-7 mol/L (corresponding
to pure
water of pH = 7) the above expression yields an overall rate constant (i.e. kB[OH- ] + kN) of 1.15 x 10-_° s-_; at an R22 concentration of 0.033 mol/L (the solubility of R22 at a partial pressure of 101.3 kPa) the corresponding
hydrolysis
value of 4.5 x 10 -12 mol/(L.s) Ellenreider
and Reinhard
rate is 3.8 x 10 -12 mol/(L.s).
given by DuPont
(1989)
(I 988) have developed
This is in reasonable
agreement
with the
at the same conditions.
an interactive,
computerized
data base for the calcula-
tion of hydrolysis rates as functions of temperature and pH. While this would be an ideal method of presenting hydrolysis
data, of the compounds
of interest
here, only methyl chloroform
is presently
included
in this
data base. In the paper by Ellenreider and Reinhard, methyl chloroform is presented as an example. At 293 K in pure water (pH = 7) the rate constant for the substitution reaction is 8.1 x 10 -9 s-1 with the neutral process dominant
by several orders of magnitude
over the base-promoted
process;
for the elimina-
tion mechanism the rate constant is 2.0 x 10 -9 s-I for the neutral process (no data are given for the basepromoted elimination process). The overall rate constant is 1.0 x 10 -8 s-_. For a concentration of 0.033 mol/L
(the saturation
The temperature expressed
concentration
dependence
in terms
of methyl chloroform)
is also given by Ellenreider
of Equation
the hydrolysis and Reinhard.
rate is 3.3 x 10 -l° mol/(L's). The overall
rate constant
can be
(9) with: A = 1.28 x 1013 s-_ -E/R
This implies that the hydrolysis Perhaps
a more convenient
life of the reacting
reaction
= -14244.
is a factor of five faster at 303 K than at a temperature
means of expressing
species. The half-life
K
the rate of a first order reaction
is independent
of reactant composition.
of 293 K.
is in terms of the half-
Ellenreider
and Reinhard
report a half-life of 0.96 year for methyl chloroform at 298 K and pH = 7. The hydrolysis rate constant for R22 yields a half-life of 191 years at the same conditions. Thus, there is a vast difference in the effectiveness
of hydrolysis
in breaking
down
a compound
in the environment.
For R123, DuPont (1989) reports a hydrolysis rate approximately 4.3 times that for R22 for a test of 100 days at 328 K. A series of 3-day tests at 358 K indicated that R141b is less stable than R123 but considerably
more stable than methyl chloroform.
In these short-term
test the amount
of decomposition
was less than 5 ppm for R123 and R141b and 0.006% for methly chloroform. "Stability" data of Allied (1989), however, report that the production of acid from R123 in aqueous solution is 38% of that with R22. The Allied information also indicates that the acid production rates with R124 and R142b are, respectively, 1.35 and 1.65 times that observed with R22. The Allied data are for tests at 314 K and result from measurements the DuPont
of the decomposition and Allied results
of fluorocarbon
suggest caution
over a period
of three months.
in the use of any hydrolysis 16
rate data.
The differences
in
PHYSICAL PROPERTIES
The database
of Ellenreider
and Reinhard,
along with a survey by Mabey
and Mill (1978), unfortunate-
ly, do not contain information on any of the other compounds of interest here. In general terms, chlorine is much more reactive than fluorine (Hine, et al. 1961) so the chlorine-free compounds (R125, R134a, R152a) will probably have lower hydrolysis rates than those reported for R22 or R123. The data for the relative reaction rates of R22, R142b, R124, R123, and Rl41b suggest that the hydrolysis rates for all of these chloroflouro dered here, others
compounds
will be of the same order of magnitude.
only methyl chloroform
will likely have half-lives
is likely to have a hydrolytic
on the order
of a century
Thus, for the nine fluids consi-
half-life
on the order of a year;
all the
or more.
3. DISCUSSION R125 The data for R 125 (pentafluoroethane) cal temperature of these values The saturated
are limited.
Both Allied (1989) and DuPont
liquid density and vapor pressure
liquid density value and graphical
presentation
data reported
by Allied were selected
of vapor pressure
given by DuPont
cients to Equations (1) and (2). A comparison of these data with the correlations 1. The critical pressure (reported in Table 1) was calculated by an extrapolation
Table
Fluid
(1989) report a criti-
of 339.4 K. DuPont also gives a freezing point temperature and critical density. are documented, but they are adopted here in the absence of any other data.
Chemical formula
None
over the single
in fitting the coeffiis presented of Equation
in Figure (1) to the
1. Fluid Fixed Points
Mol.
Tr. Pt.
Norm.
Boiling
Pt.
Critical
Point
mass
temp.
temp.
liq. den.
temp.
pres.
density
(g/mol)
(K)
(K)
(kg/m 3)
(K)
(kPa)
(kg/m 3)
R125
CF3CHF2
120.020
170.
224.6
1515.
339.4
3631.
571.5
R22
CHC1F2
86.468
113.
232.4
1409.
369.30
4990.
513.0
R134a
CF3CH2F
102.030
172.
247.1
1373.
374.21
4056.
515.3
R152a
CHF2CH3
66.050
156.
249.0
1011.
386.44
4520.
368.0
R124
CHC1FCF3
136.475
74.
261.2
1472.
395.65
3640.
560.0
R142b
CH3CCIF2
100.495
142.
264.0
1193.
410.25
4246.
435.0
R123
CHCI2CF3
152.930
166.
301.0
1456.
456.94
3674.
549.9
R141b
CH3CC12F
116.950
170.
305.3
1216.
481.5
4540.
464.1
methyl chlr.
CH3CC13
133.405
243.
347.3
1250.
545.
4300.
470.0
*Note: None of the critical densities are known to four significant figures; they are given to this level for consistency with Eqn (2). 17
PHYSICAL
PROPERTIES ,
('d
I
,
I
i
I
,
TO
o t'-_k
a. A
O
Q. =
t,-
i
•
Allied
data
T c X
200
r
240
280 Temperature
,
(N
F
I
,
320
360
(K) I
t--
o o
C_ "" A
O
C_ i u
Q; v
•
Allied
data
iTc
N
200
24'0
280 Temperature
Figure
1, Comparison
of correlations
with
data
for
density.
18
R125;
3;20
360
(K)
a) vapor
pressure;
b) saturated
liquid
PHYSICAL PROPERTIES
critical temperature (1989).
(an extrapolation
of only 6.3 K) rather than the value of 3520 kPa reported
As with all the fluids in this report,
obtained
by finding the temperature
(101.325
the normal
boiling point temperature
at which Equation
(1) yields a pressure
in Table
of one standard
1 is
atmosphere
kPa).
The eight liquid densities K using glass flotation
reported
by Allied were measured
beads of known density.
over the temperature
In this technique,
the temperature
so that the density of the fluid matches that of one of the beads. In another son and Basu 1988), the accuracy apparently
reported
by DuPont,
not corrected
of [his method
for the effects
is claimed
of temperature
range 228.7-336.3
of the fluid is adjusted
work by the same group (Wil-
to be 0.2 kg/m 3. The values
on the densities
for R125 were
of the glass beads.
Judging
by
other results by this method, these corrections should be less than 0.1 kg/m 3 for the temperature range of the measurements for R125. The excellent fit of Equation (2) to within 6 K of the critical temperature gives
some credence
to the critical
The only information tion (4) reported
on solubility
by DuPont
(1989).
density
of DuPont
used in the correlation.
in water were coefficients The experimental
technique
malee (1953). No data were given but an "experimental coefficients
are reported
to a correlation
was similar to that employed
data range"
in Table 4 after the appropriate
similar in form to Equa-
conversion
of 298-333
K was indicated.
by ParThese
of units.
R22 The extensive
body of data on R22 (chlorodifluoromethane)
in the treatise by the Japanese
Association
of Refrigeration
Table 2. Vapor
Fluid
is summarized,
evaluated,
and correlated
(1975). Although additional data have been meas-
Pressure
Temperature low (K)
limits high (K)
a_
Coefficients to Equation (1) a2 a_ (p in kPa, T in K)
a4
RMS error (%)
R125
233.
Tc
-2678.571
16.63306
-0.001602304
1.390420
0.12
R22
223.
Tc
-2907.443
17.05244
-0.001796055
2.204052
0.09
R134a
210.
Tc
-3353.464
18.36056
-0.002908044
2.783663
0.19
R152a
273.
Tc
-3110.511
17.02405
-0.001445740
2.105154
0.05
R124
222.
Tc
-3471.946
18.16083
-0.002997217
2.703744
0.35
R142b
233.
369.
-3382.422
17.01384
-0.001012149
3.224924
0.30
R123
243.
Tc
-4060.080
18.20783
-0.002426370
3.164297
0.17
R141b
243.
475.
-4388.810
18.40668
-0.001808752
5.149630
2.20
methyl chlr.
295.
371.
-4809.873
17.93429
-0.001362322
4.617096
0.02
19
PHYSICAL
PROPERTIES
TABULATED VALUES OF VAPOR PRESSURE, LIQUID DENSITY AND SOLUBILITY IN WATER Properties (Parentheses
Temp.
of R125 indicate
Properties
extrapolation
Vapor Pressure
of
Sat.
data)
Liq.
(Parentheses
Henry's
const.
of R22 indicate
Temp.
Density
extrapolation
of
data)
Vapor
Sat.
Liq.
(oC)
(kPa)
(°C)
Pressure (kPa)
-40.0
150.6
1484.0
-40.0
105.3
1406.5
186.9
-35.0
(kg/m
J)
(kPa/Mass%)
Density (kg/m 3)
1465.4
-35.0
132.0
1391.8
-30.0
229.8
1446.3
-30.0
163.8
1376.9
-25.0 -20.0
280.1 338.5
1426.8 1406.8
-25.0
201.2
1361.8
-20.0
245.1
1346.4
- 15.0
406.0
1386.2
-15.0
295.9
1330.6
-10.0
483.3
1365.0
-10.0
354.5
1314.6
-5.0
571.4
1343.1
0.0
671.2
1320.4
(
242.)
-5,0 0.0
421.6 498.0
1298.2 1281.5
5.0
783.7
1296.8
I
331.)
10.0 15.0
909.8 1050.7
1272.2 1246.4
( (
448.) 599.)
5.0 10.0
584.3 681.3
1264.3 1246.7
20.0
1207.2
1219.3
(
794.)
25.0 30,0
1380.6 1571.9
1190.4 1159.6
Henry's
const.
(kPa/Mass
82.)
15.0
789.9
1228.6
1223 171. 227.
20.0
910.8
1210.0
288.
1042. 1355.
25.0
1044.9
1190.7
354.
30.0
1193.1
1170.8
425.
35.0
1782.4
1126.2
1747.
2013.4
1089.7
2234.
35.0 40.0
1356.1 1534.8
1150.1 1128.6
498.
40.0 45.0
2266.2
1048.8
2835.
45.0
1730.3
1106.0
50.0
2542.5
1001.8
3572.
50.0
1943.4
1082.3
650. 727.
55.0
2844.1
945.3
4469.
55.0
2175.3
1057.1
805.
60.0 65.0
3173.5 3534.4
870.5 735.8
(5553.) (6857.)
60.0
2427.1
1030.3
883.
65.0
2700.0
1001.3
961.
70.0
2995,4
969.7
1038.
75.0
3315.1
934.4
1114.
80.0 85.0
3660.8 4035.1
893.9 845.2
1189.) 1263.)
90.0
4441.6
780.6
95.0
4886.2
660.9
1336.) 1408.)
NBP:-48.6
(101.3)
(1515.2)
Tc:
(3630.6)
(571.5)
66.3
NBP: Tc:
20
-40.8
101.3
(1408.9)
96.2
(4995.6)
( 513.0)
573.
_)
PHYSICAL PROPERTIES ured since the publication of this work, the recommendations limited time available for this project could be better expended
of the JAR were adopted here so that the on other fluids for which no such compila-
tions exist. The triple
point and critical
point values
were fit by the JAR based largely
of the JAR are adopted
on the data of Zander
here.
The saturated-liquid
densities
(1968) to the same form used here (Equation
(2)) and thus the coefficients given in Table 3 are those reported by the JAR. This correlation from 204 K to the critical temperature with an RMS deviation of approximately 0.1%.
is valid
The vapor pressure data of Kletskii (1964), Kohlen (1985), and Zander (1968) were fit to Equation (1); the residuals are shown in Figure 2. The three lowest temperature (203.3-211.3 K) points of Zander and his point at 366.1 K were excluded from the fit. The high temperature
point appeared
to be anomalously
high compared to the other data sets while the three low temperature points could not be fit without seriously affecting the correlation at higher temperatures. (In Figure 2 and all similar residual plots, points used in the correlation are shown as filled-in symbols; points excluded from the fit are shown as open symbols.) R22 solubility data are reported by Parmelee (1953). Fourteen data points at three temperatures were measured with an estimated accuracy of 5 % using a gas volumetric technique. Parmelee correlated his data to a form similar to Equation conversion
(4) and his coefficients
are reported
in Table 4 after the appropriate
of units. ¢N
Q O o
el
•If"
O
•
.. "
'
"'"
¢D
el i
_o el m,i
• data of Kletskii • data of Zander • data of Kohlen i
200
240
!Tc i
i
T
280
320
360
400
Temperature (K) Figure 2. Comparison of vapor pressure correlation with data for R22; filled-in and open symbols indicate points used and not used, respectively, in fitting correlation. 21
PHYSICAL PROPERTIES R134a Refrigerant property
134a (1, l,l,2-tetrafluoroethane)
community
measured
recently,
has been the focus of considerable
and considerable
data have become
available.
by Kabata, et al. (1988), Wilson and Basu (1988), and Morrison
tion, carried agreement.
out at NIST, DuPont
Two reliable
is adopted
(1989)
sources
here,
and Daikin
of vapor
although
pressure
data are available;
from 211.0 K to within 1 K of the critical temperature. ed accuracy
parameters
temperatures
together
et al. (1988)
K. Unfortunately,
presented
Weber (1989) measured
have measured
reported by three independent groups. wide range of temperature (238.9-371.6 six measurements 268.2-368.2
in the vicinity
the vapor pressure
in fitting Equation
(2); the residuals
a vibrating tube densimeter are in reasonable agreement,
points. Saturated
range
22 values with an estimatof 0.7-7.
kPa (depend-
over the temperature
in McLinden,
of R134a at 25 temperatures
point.
Morrison
mercury-displacement are shown in Figure
were not available although differences
et al. (1989). from 253-371
liquid densities
have been
(1989)
apparatus. 3. (Further
has measured
11 values
from
These three data sets were used measurements
by Morrison
using
in time to include in this work.) The different data sets of as much as 1.5 % exist, especially near the critical point.
of R134a in water has been measured
points were read off their graphical
are in excellent
Wilson and Basu (1988) report nine measurements over a fairly K) using the floating bead technique. Kabata, et al. (1988) report
of the critical
K with a variable-volume,
The solubility
here is identical with that presented
their paper does not give the experimental
determina-
of 172 K.
As shown in Figure 3, the two data sets are in excellent agreement
range of overlap. The correlation
point has been
they span the temperature
of 0.2 kPa. Wilson and Basu (1988) report 32 values with an accuracy
ing on the pressure). Yamashita,
The critical
in the fluid
(1989). Morrison's
all three sets of critical
(1989) both report freezing
attention
presentation
by DuPont
(1989)
at 298 and 353 K. These two
and used to fit the coefficients
in Equation
(4).
R152a The primary
source of data for R152a (1,1-difluoroethane)
was the work of Higashi,
et al. (1987). Their
critical point determination is consistent with the earlier determination by Mears, et al. (1955), which is the basis of the critical parameters listed on many manufacturer's data sheets. The determination by Higashi, et al. is, however, of much higher accuracy (0.01 K for temperature, 1.0 kPa for pressure, and 2 kg/m 3 for density) and is adopted here. The freezing point reported by DuPont (1989) is used here. Higashi,
et al. report 44 vapor pressure
measurements
from 273.1
K to within 0.4 K of the critical
temperature temperature
with a precision better than 0.17%. Additional data, of lower accuracy but covering a wider range (203.7 K and above), are reported by Mears, et al. The data sets of Higashi, et al.
and Mears,
et al. are in reasonable
agreement
above 290 K but diverge rapidly
see Figure 4. (In Figure 4 and all similar figures, residuals
greater
of Equation
points drawn just outside the frame of the plot indicate
than the limits of the ordinate and are not to scale.)
(1) to lower temperatures
a much poorer
fit at the higher
All attempts
by including selected low temperature
temperatures.
at lower temperatures;
The accuracy
to extend
the range
points of Mears resulted in
of the data by Mears,
et al. is difficult to
ascertain but is probably no better than 5-10 kPa; this uncertainty would be equivalent to an error of as much as 10% at the lowest temperatures. Thus, only the vapor pressure data of Higashi, et al. were used in fitting Equation
(1). 22
PHYSICAL
PROPERTIES
i
(N
t-Q 0 Mk
•
O. A
• mm
'_,_
0
=
•
o .,_mr
Q. 0 c_ a. v 'T,
• data • data
of Weber of Wilson
& Basu
T c
(N i
200
240
r
280
i
J
360
320
Temperature i
[
_
400
(K)
=
i
L
J
n
Q Q
O;
• •
•
:
• m:
• •
• m:
i _u
i
• data of Wilson • data of Kabata •
data
& Basu et al.
of Morrison
iT c
N
200
240
280
320
Temperature
Figure 3. Comparison density.
of correlations
with
data for R134a;
23
360
400
(K)
a) vapor
pressure;
b) saturated
liquid
PHYSICAL
Properties (Parentheses
Temp. (°C)
Properties
of R134a indicate
extrapolation
Vapor Pressure (kPa)
of
(Parentheses
data)
Sat. Liq. Density (kg/m
3)
Henry's
Temp.
const.
of R152a indicate
extrapolation
Vapor Pressure
(kPa/Mass%)
('C)
(kPa)
of
data)
Sat.
Liq.
Henry's
const.
Density (kg/m
3)
(kPa/Mass%)
-40.0
51.6
(1413.51
-40.0
-35.0
66.5
(1399.2)
-35.0
-30.0 -25.0
84.7 106.6
1384.6 1369.8
-30.0 -25.0
97,6)
1013.0
-20.0 -15.0
132.9 164,1
1354.8 1339.5
-20.0 -15.0
121.2)
1002.6
149.0)
992. l
-10.0
200.7
1324.0
-10.0
181.8)
981.3
-5.0
243.4
1308.2
-5.0
0.0
292.9
1292.1
3O2.)
0.0
219.9) 263.9
970.3 959.1
178.
5.0
349.8
1275.7
359.)
5.0
314.6
947.7
207.
10.0
414.8
1258.8
425.)
10.0
15.0 20.0
488.7 572.1
1241.5 1223.8
499.)
15.0
372.5 438.2
936.0 924.0
239. 275.
665.8 770.7
1205.5 1186.7
583.) 678.
20.0 25.0
512.5 596.0
911.7 899.0
316.
25.0 30.0
784.
30.0
689.4
886.0
409.
35.0
887.4
1167.1
35.0
793.4
872.6
462.
40.0
1017.0
1146.8
903. 1035.
40.0
908.9
858.8
521.
45.0
1160.1
1125.7
1181.
45.0
1036.5
844.5
584.
5(I.0
1317.8
1103.4
1342.
50.0
55.0
1491.0
1080.0
1520.
55.0
1177.1 1331.5
829.7 814.2
654. 729.
60.0
1680.7
1055.1
1714.
60.0
1500.5
798.1
809.
65.0 70.0
1888.2 2114.6
1028.5 999.6
1927.
1685.1 1886.2
781.1 763.2
896.
2158.
65.0 70.0
75.0
2361.5
967.9
2409.
75.0
2104.8
744.2
(1o9o.)
80.0
2630.4
932.4
2682.)
80.0
2342.1
723.9
(1197.)
85.0
2923.4
891.4
2976.)
85.0
2599.3
701.8
(131o.)
90.0
3243.1
841.7
3293.)
90.0
2877.9
677.5
95.0
3593.0
775.3
3634.)
95.0
3179.4
650.1
(1432.) (1560.)
100,0
3979.6
650.9
3999.)
100.0
3505.8
618.1
(1696.)
-24.2 113.3
101.3
1011.2
4519.8
368.0
NBP:-26.1 Tc:
PROPERTIES
101.1
101.3 4067.9
NBP:
1373.1
Tc:
515.3
24
48.0)
1043.0
61.5) 77.9)
1033.2 1023.1
360.
990.
PHYSICAL PROPERTIES ,
(N
I
i
J
,
,
I
,
I
0
o data of Mears et al. • data of Higashi
qe-
0 0 y_
,
E E .J
m
°--
e-
Q
?
e-
E o
L.)I 'q 'tuJe; fSJeu9 uo!_.ehp,:)V 0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
-z_ _/
0 0 0
"_
_ e-
E .--
q r,,
O
E
"-
EE
o CD
q Q; '_
mx::
d E .-J 0
E i
o tN
0
If) 0
143
cO
?
"t-
_
"_
TROPOSPHERIC LIFETIMES
At the end of the 100 year model experiment, total halocarbon
injection
rate to determine
the total model halocarbon
the halocarbon
lifetime.
hydroxyl radical concentrations implies low tropospheric tropospheric hydroxyl radical concentrations. For reactive centrations
inventory
The assumption
was divided
by the
of fixed tropospheric
halocarbon loadings so as not to perturb the halocarbons, this implies that halocarbon con-
are not more than 1 ppb at the most.
Figure 8 shows the total lifetimes including both tropospheric OH oxidation and stratospheric removal calculated for various assumptions concerning the form of the temperature dependent OH + halocarbon rate coefficient. lifetime, factors
Clearly,
this temperature
with lifetimes
covering
and activation
However
parameter
exerts a dominant
0.2 - 30 years for reasonable
ranges in expected
influence
on halocarbon
values of preexponential
energies.
the _4CO method is not uncertainty-free
mining halocarbon sumptions
dependent
lifetime
is dependent
and its accuracy
and precision
on a whole range of experimental,
which may be called into question.
Volz, Ehhalt and Derwent
as a means
of deter-
life cycle and modelling (1981)
as-
gave some thought
to
uncertainty limits on their tropospheric OH distribution which this reevaluation has not changed. They recommended a mean tropospheric OH concentration of 6.5 +_3 molecule cm -3. Assuming that the kinetic parameters
defining
the OH
+ halocarbon
rate coefficient
are described
with complete
certainty,
we
can use the 1-sigma confidence limits for the tropospheric OH distribution to determine the confidence limits of the halocarbon lifetime. The Harwell two-dimensional model was therefore rerun with the entire tropospheric
OH distribution
ing upper and lower
scaled upwards
1-sigma confidence
factor of two for all the halocarbons
examined.
mined for the longer-lived
halocarbons,
Lifetimes
Fluorocarbons
of Alternative
and downwards
For some of the candidate alternative
to the 1-sigma confidence
limits of the halocarbon Lifetimes
lifetimes
were apparently
limits. The result-
encompassed
the range of a
slightly more accurately
reflecting the influence of the assumed constant stratospheric
fluorocarbons
deter-
removal.
evaluated chemical kinetic data for the OH + halocar-
bon degradation reactions are already available, Table 2. The lifetimes of these halocarbons due to stratospheric removal and tropospheric OH radical degradation can therefore be determined using the Harwell two-dimensional
model. Table 2 gives the atmospheric
latitudes of the northern
hemisphere
lifetimes
calculated
from a 100 year model calculation.
for a constant
The tropospheric
injection
in mid-
OH distribution
calculated with the _4CO method gives lifetimes for the alternative fluorocarbons in the range 0.3-635 years. For most of the alternative halocarbons, these lifetimes are considerably shorter than the corresponding lifetimes
for the fully halogenated
To complete
the environmental
haviour of any chlorine-containing haviour
of the fragments
halocarbons. acceptability molecular
work, modelling fragments
could readily be incorporated
magnitude of any CFCI2CO(O2)NO2,
stratospheric CF2CICHO,
chlorine-containing
fragments
produced
studies are required
following
by the halocarbon
degradation.
into the two-dimensional
up the beThe be-
model to determine
the
fluxes of species such as COC12, COHC1, CF3COCI, CFC12CHO, CF2C1CO(O2)NO2, COFC1 and so on. Competing processes for these
would include tropospheric
scavenging. 144
degradation,
dry deposition,
photolysis
and wet
TROPOSPHERIC LIFETIMES
Table
2.
OH
+ halocarbon
rate coefficients
and atmospheric
lifetimes
for a range
of alternative
fluorocarbons Lifetime, c OH Formulae
+ halocarbon rate coefficient, cm 3 molecule-i s-_
yrs Stratospheric loss
None
CH3F
5.4 x 10 -lz exp(-1700/T)
3.12
3.33
CHzFz
2.5 x 10 -lz exp(-1650/T)
5.40
6.0
CHF3
7.4 x 10 -13 exp(-2350/T)
46.35
635.0
CHzFCI
3.0 x 10-12 exp(-1250/T)
1.23
1.26
CHFC12
1.2 x 10 -_2 exp(-I IO0/T)
1.74
.80
CHF2CI
1.2 x 10 -12 exp(-1650/T)
10.35
13.0
CH3CH_F
1.3 x 10 -11 exp(-1200/T)
0.31
0.31
CHzFCH2F
1.7 x 10 -I1 exp(-1500/T)
0.59
0.60
CH3CHF2
1.5 x 10 -lz exp(-llOO/T)
1.42
1.46
CH2FCHF2
2.8 x 10 -12 exp(-15OO/T)
2.98
3.17
CH3CF3
2.6 x 10 -13 exp(-1500/T)
22.29
40.2
CHFzCHFz
8.7 x 10 -13 exp(-1500/T)
8.64
10.4
CHzFCF3
1.7 x 10 -lz exp(-1750/T)
10.40
13.1
CHF2CF3
3.8 x 10 -13 exp(-1500/T)
17.06
25.9
CH3CFCIz
2.7 x 10 -13 exp(-1050/T)
5.89
6.68
CH3CFzC1
9.6 x 10 -_3 exp(-1650/T)
12.49
16.6
CHzC1CFzC1
3.6 x 10 -lz exp(-1600/T)
3.28
3.51
CH2C1CF3
5.2 x 10 -13 exp(-1100/T)
3.80
4.11
CHC12CF3
6.4 x 10 -13 exp(-850/T)
1.36
1.40
CHFC1CF3
6.6 x 10 -13 exp(-1250/T)
4.99
5.54
Notes: a. Chemical kinetic data from Hampson, Kurylo and Sander (1989) b. T is absolute temperature in K c. Lifetimes in steady state have been determined in a two-dimensional model assuming a northern hemispheric and constant injection rate, allowing for either 2 % yr stratospheric removal or not d. The l-sigma confidence limits on the lifetimes encompass a range of a factor of two.
145
TROPOSPHERIC LIFETIMES 4. CONCLUSIONS A review of the 14CO method
for determining
ealed a number of areas where changes
the tropospheric
have occurred
hydroxyl
since the original
radical distribution
publication
has rev-
of Volz, Ehhalt and
Derwent (1981). None of these changes has however forced a revision of the approach. They have served to complete our understanding of areas which were difficult to understand in the early work. The chemical kinetic data is notable in this regard. concentrations evaluation.
may have been under-estimated
For the expected ponential
factors
OH
procedure.
halocarbons
It is important
+ halocarbon
and activation
a simple graphical lifetimes,
It is now much easier to understand
chemical
energies,
rate coefficient
it is possible
The '4CO approach
with reasonable
to remember
in the photochemical
precision,
why the early hydroxyl
models as compared
parameters
to estimate
allows the determination 1-sigma confidence
that OH + halocarbon
rate coefficients,
defined
resulting
to the 14CO
in terms
halocarbon
radical
of preex-
lifetimes
of tropospheric
using
halocarbons
limits spanning about a factor of two. hydroxyl
distributions
and halocar-
bon concentrations exhibit important covariance terms so that halocarbon lifetimes are not well-determined quantities. The lifetimes determined in this review are valid only for halocarbons injected at the northern hemisphere
surface
To illustrate
over the latitude range of the major continental
the L4CO method, the graphically +3
determined
land masses and population
lifetimes
centres.
for methane and methyl chloroform
are found to be 7 -2 and 5 ± 2 years, respectively, which are in close accord with our two-dimensional model studies (Cox and Derwent 1981; Derwent and Eggleton 1978), and current literature evaluations (Ehhalt 1988; Prinn 1988). The current methyl chloroform lifetime overlaps the ALE/GAGE 6.3 +-0.9 1.2 years and confirms both estimates since they are completely independent. Lifetimes
of some candidate
studies using the Harwell the subsequent transport parent halocarbon. There
is mounting (Rowland
to become
characterised
1. In considering
fluorocarbons
two-dimensional
model.
and fate of the secondary
evidence
atmosphere
alternative
that man's activities
and Isaksen
in Table 2 based on detailed
These studies should be readily degradation
products
are inducing
changes
extended
liberated
to include
by OH attack on the
in the composition
of the global
1988). Some of the trace gases for which global trends are beginning
play an important
the environmental
have been tabulated
evaluation,
role in global tropospheric
acceptability
of alternative
chemistry,
fluorocarbons,
as described
an attempt
in figure
should be made
to investigate their tropospheric sinks in future scenarios in which the composition of the global troposphere has been grossly perturbed by man's activities. For example, future subsonic aircraft operations may increase local tropospheric that would decrease
OH concentrations
tropospheric
lower bounds on the lifetimes
(Derwent
OH concentrations. of alternative
1982) and other perturbations A scenario
fluorocarbons
approach
can be put forward
could help to put upper and
over the next 50 years.
5. ACKNOWLEDGEMENTS The two-dimensional United Kingdom
modelling
Department
work at Harwell
of the Environment
employed
in this review was sponsored
Air Pollution 146
Research
Programme.
as part of the
N92-15440
TROPOSPHERIC
HYDROXYL
CONCENTRATIONS
HYDROCHLOROFLUOROCARBONS
AND THE LIFETIMES
OF
(HCFCs)
Michael J. Prather NASA/GISS 2880
Broadway,
New
York,
NY 10025
PRECEDING
PAGE
BLp._;K NGT
F;LMED
TROPOSPHERIC HYDROXYL ABSTRACT Three-dimensional
fields of modeled tropospheric OH concentrations
are used to calculate lifetimes against
destruction by OH for many hydrogenated halocarbons, including the CFC alternatives (hydrochlorofluorocarbons or HCFCs). The OH fields are taken from a 3-D chemical transport model (Spivakovsky et al.,
1989) that accurately
of 5.5 yr). The lifetimes
simulates
the global
measurements
of various hydro-halocarbons
of methyl chloroform
are shown to be insensitive
(derived
to possible
spatial vari-
ations and seasonal cycles. It is possible to scale the HCFC lifetimes to that of methyl chloroform by using a ratio of the rate coefficients
for reaction
with OH at an appropriate
temperature,
lifetime
or methane about 277 K.
1. INTRODUCTION Synthetically produced halocarbons that contain chlorine and bromine, often called chlorofluorocarbons (CFCs) and halons, pose a direct threat to the stratospheric ozone layer (e.g., NASA/WMO, 1986; Watson et al.,
1988) and also contribute
substantially
to the greenhouse
1975; Lacis et al., 1981). A single characteristic problems
is their
stratosphere.
long atmospheric
bons, environmentally
acceptable
One key property
loss in the troposphere
fluorocarbons
loss of these HCFCs averaged,
fined as the global atmospheric
sunlight
there will soon be international
Workshop,
in the
restrictions
16-17 May 1989, Boulder residence
on
fluorocarColorado).
time, implying
surface. contain hydrogen by reaction
(hydrochlorofluorocarbons with tropospheric
by the ratio of emissions
annual mean lifetime content
these environmental
only by ultraviolet
must be a short atmospheric
is dominated
(units: kg) will be controlled
The globally
(Ramanathan,
and there is now a search for alternative
(AFEAS
compounds
or at the Earth's
Many of the suggested alternative the atmosphere
concerns,
Protocol,
substitutes
of these alternative
and atmospheric (yr-t).
most are destroyed
As a result of these environmental upon in the Montreal
efficient
of CFCs and hal ons that aggravates
lifetimes;
CFC growth as agreed
forcing of the climate
(kg yr -t) to atmospheric
(yr) of the HCFCs
(kg) divided
or HCFCs),
OH. Their buildup
(against
by the total annual
in
destruction
atmospheric
loss) is de-
loss (kg yr'l).
In this report we derive the lifetime of HCFCs and other hydrogenated halocarbons in two ways. The primary method involves modelling the OH distribution from first principles, specifying or predicting the HCFC
distribution,
tropospheric NOx,
CO,
and then integrating
OH fields are calculated CH4
the HCFC
loss over the globe (e.g.,
from a global 3-D climatology
and other hydrocarbons
(see Spivakovsky
et al.,
Logan et al.,
of sunlight,
temperature,
1989). Uncertainties
OH concentrations occur not only with the kinetic model, but also with the global other trace gases and cloud-cover needed as input to the photochemical model. The OH fields used here were developed Transport CH3CC13
Model
(CTM).
With the CTM,
in order to simulate the latitudinal
sources,
and seasonal patterns,
global transport
x time) is applied here to test various
tropospheric
distribution;
methyl chloroform
climatologies
hypotheses
it is used also to test the accuracy
of the
in a 3-D Chemical
and chemical
losses of
and the global trends (see Spivakovsky
et al., 1989). Similar CTM modelling of all the HCFCs is impractical and geographical location of emissions. Instead, the four-dimensional altitude
03, H20,
in the calculated
and applied to study methyl chloroform we specified
1981). The
and would require OH field (latitude
on the sensitivity
of HCFC
also a history x longitude x
lifetimes
of scaling the HCFC lifetimes
to their
to an assumed
lifetime. 149
PRECEDING
PAGE
BLP_,'K
NGT
F;LMED
TROPOSPHERIC HYDROXYL The second method for deriving HCFC lifetimes selects a reference species with a global budget and atmospheric lifetime (against OH destruction) that is thought to be well understood (see Makide and Rowland, 1981). The lifetime of methyl chloroform,
derived
CH3CC13,
from the ALE/GAGE
analysis
is often used
(Prinn et al., 1987) and is then scaled by the ratio of the rate coefficients for reaction with OH (Hampson, Kurylo and Sander, AFEAS, 1989), k(OH + CH3CC13)/k(OH + HCFC), to calculate the HCFC lifetime. Possible errors
in this approach
are associated
with the assumed
lifetime
for CH3CC13, and with the use
of a single scaling factor that does not reflect the different spatial distribution of the HCFCs. This scaling approximation is tested here for plausible global patterns in the HCFC concentration and for different temperature
dependence
The tropospheric methane
of the rate coefficients.
chemistry
model for OH is described
and methyl chloroform
in Section
in Section
3, and then compare
2. We calculate
the results for methyl chloroform
other published values. The integrated losses for a range of possible distributions in Section 4. HCFC lifetimes and uncertainties are discussed in Section 5.
2. THE CHEMICAL The lifetimes
with
of an HCFC are given
MODEL
calculated
here for the HCFCs,
global distributions of OH from the photochemical (CTM developed
the global losses for
at GISS & Harvard).
as well as for
CH3CCI3,
model developed
CH3Br and CH4, use
CH3CI,
for the 3-D Chemical Transport Model
The model for tropospheric
OH is based on a 1-D photochemical
model (an updated version of Logan et al., 1981 ; DeMore et al., 1987) that has been used to parameterize OH concentrations as a function of sunlight and other background gases (see Spivakovsky et al., 1989). This parameterized chemistry has been used to calculate a three-dimensional set of mean OH concentrations for the CTM grid over one year: the diurnally averaged OH concentrations are stored at 5-day intervals with a spatial resolution of 8 degrees latitude by 10 degrees longitude over 9 vertical layers (see Prather et al., 1987 for CTM documentation) for a total of more than 1/2 million values, even at this coarse resolution. The 5-day average temperatures The local independent Circulation
variables
needed to derive OH concentrations
Model (5-day averages
et al., 1983) and from observed
at each grid point are also stored.
of pressure,
climatologies
ozone column). The observational 4-D fields, and we have assumed the continental
for details
and the maritime
of the assumed
The annual corresponding
averages
trace-gas
see Hansen
(CO, 03, CH4, NOx, H20 above 500 mbar and stratospheric
is that from the available
troposphere
climatology
up to 3 km altitude.
and the chemical
of the zonal mean OH concentrations
annual average
are taken from the parent General
water vapor and cloud cover;
database for most of these species is insufficient to define the necessary zonally uniform distributions with smooth variations over latitude, alti-
tude and season for most species. One exception between
temperature,
temperatures.
Hydroxyl
over the tropics. The OH density peaks at 700-800 reduce solar ultraviolet light below 800 mbar.
ture, density and trace gas abundance.
mbar because
The integrand
et al. (1989)
lb gives the
are highest in the middle troposphere cloud cover
and Rayleigh
over a wide range of conditions
is extremely
150
See Spivakovsky
parameterization.
are shown in Table la; Table
concentrations
The global loss of a gas that reacts with OH is the integral
data we are able to differentiate
non-linear,
scattering
in tempera-
and thus, the average
loss
TROPOSPHERIC HYDROXYL Table l a. Annual Average OH concentration(104cm"_) LATITUDE 90S P(mbar) 100 150 200 300 500 700 800 900 1000
84S
33 31 41 51
76S
32 27 36 44 42
30 24 32 41 40 31
68S
25 21 30 42 44 32 20
60S
52S
25 23 36 43 36 14 11
24 26 45 51 48 21 16
44S
30 33 63 68 65 35 28
36S
28S
20S
12S
4S
4N
12N
20N
28N
36N
44N
52N
60N
68N
76N
84N
90N
38 43 81 89 89 65 52
20 43 52 62 119 139 144 114 92
26 51 57 76 131 154 157 124 105
43 68 65 80 135 159 152 123 103
40 59 58 77 147 180 168 130 112
35 54 52 72 141 182 168 134 112
30 49 48 65 124 171 159 135 112
26 44 43 59 118 159 155 126 107
19 34 36 50 108 139 140 110 88
30 39 80 111 130 116 86
21 28 61 88 108 90 63
17 21 45 64 79 62 43
18 20 40 58 67 53 40
17 21 34 56 77 59 46
20 28 41 53 52 23 17
22 32 46 56 56 26 21
20 33 44 32 32 20 10
Table lb,
Annual
Average
Temperature
(°K)
LATITUDE 90S P(mbar) 1(30 150 200 300 500 700 800 900 1000
84S
206 216 232 247
76S
209 217 236 248 255
209 216 237 248 256 264
68S
211 219 240 254 258 262 267
60S
52S
212 221 244 259 264 268 271
213 224 247 263 268 273 276
44S
214 228 252 267 273 278 282
Quantities
are the annual
No values
for OH or T are reported
At ifigher pressures
36S
28S
20S
12S
4S
4N
12N
20N
28N
36N
44N
52N
60N
68N
76N
84N
90N
217 233 257 272 278 283 287
207 215 222 239 263 277 283 288 291
204 215 225 244 268 282 287 291 295
203 215 225 246 270 283 288 293 297
202 215 225 246 270 283 289 293 297
202 215 226 247 270 283 289 294 297
202 216 226 246 270 284 289 294 298
203 216 225 245 269 283 289 294 297
206 215 223 241 266 280 286 291 293
220 236 260 275 280 285 289
217 231 255 270 275 279 283
215 227 250 265 270 275 277
214 225 248 262 267 270 272
214 223 245 259 264 267 268
214 222 244 258 262 265 268
214 222 242 256 261 263 267
215 217 225 235 239 244 246
zonal average
over Antarctica
of the 4-D fields described
for the extra-tropical the number
Table 2. Global
integrating
Average
dm
96
exp(-1700/T)
dm
105
exp(-1800/T) exp(-2300/T)
dm dm
106 111
dm
to report
a zonal average.
OH concentrations
effective
T (K)
(e.g.,
259 262 263 265
91 65
over mass (dm, from the surface
in temperature
200 mbar).
80
exp(- 1000/T)
Integrals
(above
of points are insufficient
OH (10 4 cm "3)
kernel
dm
(1 + 0.6/P) dz
in the text.
stratosphere
-1700/T
volume
(dz) preferentially
average
OH with the effective
for
cn4),
to 100 mbar)
are weighted
and linear in pressure
weight the lower atmospheric temperature
in the exponential 151
(i.e.,
densities
by different 1 + 0.6/P
factors:
for CO). Integrals
in the upper troposphere.
gives the correct
exponential
global
over
Use of the
integral.
TROPOSPHERIC HYDROXYL is not equal simply to the product a single "global
average
OH concentrations
of averages
(Makide
OH concentration"
averaged
and Rowland,
without qualifying
over the atmosphere
(100-1000
temperature
high temperatures because
dependence
average
OH because
of air in the upper troposphere
to report The global
contribution)
are
The average OH is largest, 11 lxl04 cm -3, with a large exponential factor of-2300/T.
in the tropics (see Table 1). The spatially averaged
of the large volumes
temperatures
result in greater
kernel.
mbar with no stratospheric
reported here in Table 2 for a variety of integrating kernels. when weighted appropriately (by mass) for loss of an HCFC A larger
1981). It is misleading
it as to the averaging
the OH densities
are maximal
at
65x 104 cm
-3,
OH density is smallest,
with low OH concentrations.
given in Table 2 are those needed to get the correct
integral,
and should
not be confused with the optimal scaling temperature in Section 4. (The scaling temperature account for the change in mean OH as the temperature dependence varies.)
must also
3. GLOBAL
integrated
loss frequency for
averaged
LOSS OF CH3CCI_ AND CH4
The globally butions
globally
The effective
losses for methane
(OH and temperature and
CH4
CH3CC13.
and for methyl chloroform
fields described
Tropospheric
are calculated
above) using realistic,
reactions
with OH dominate
by integrating
but fixed tropospheric
the
distri-
the loss of both species,
but
stratospheric losses cannot be ignored and are used in place of OH densities in layer 9 (0-70 mbar) globally and in layer 8 (70-150 mbar) outside the tropics. The stratospheric losses are calculated from a 1-D vertical
diffusion
The assumed
model for stratospheric conditions
ble 3. The lifetime
and resulting
of methane
chemistry
evaluated
atmospheric
at the appropriate
and season.
losses of CH4 and CH3CCI3 are summarized
is 8.7 yr with about 6 % of the loss occurring
Table 3. Global
latitude
budgets
for
CH4
CH4
in the stratosphere
in Ta-
and more
and CH3CCI3
CH3CCIj
Rate coefficient k(X + OH)
2.3xl0-t2e-17°°/T
5.0xl0-12e -lsoo/T
Concentration NH ( 28
°)
SH Atmospheric
content
Atmospheric
losses
total tropics
(2-6 krn)
stratosphere Lifetime
1700/1700
ppb
140/150
ppt
1600 ppb
110 ppt
4580 x 1012g
2930 x 109g
524 x 1012g
534
270 x 10_2g
260 x 109g
29 x 1012g
53 x 109g
8.7 yr
x 109g
5.5 yr
Budgets based on integration of 4-D tropospheric OH fields with zonally fixed, non-seasonal as noted. Stratospheric profiles and losses are included.
152
distributions
TROPOSPHERIC HYDROXYL than half in the tropical
middle troposphere.
loss for methyl chloroform becomes
important
The lifetime
of methyl chloroform
is 5.5 yr. Stratospheric
is about three times more rapid than for methane because photolysis of
in the stratosphere.
Again the tropical
middle troposphere
accounts
CH3CCI
3
for about half of
the global loss.
Methyl chloroform is usually chosen as a reference species for tropospheric mospheric lifetime based on the ALE/GAGE analysis of Prinn et al. (1987). in Table 3 for
CH3CC13
(Spivakovsky
et al, 1989). The ALE/GAGE
industry
with those from the ALE/GAGE
data for atmospheric
global lifetime
emissions,
of 6.3 yr with a reported
analysis
analysis
and the recent 3-D CTM simulations
uses observations
and a 9-box atmospheric 1-sigma range of 5.4-7.5
loss, with a "known" atWe compare the lifetimes
of
model,
CH3CCI
3
to derive
yr. Errors
at 5 surface an annual
in the lifetime
sites,
average
due to uncer-
tainties in the atmospheric emissions used in the ALE/GAGE study have been reduced by recent analyses of CHaCCI3 sources from industry surveys (Midgley, 1989) and from observations (Prather, 1988).
When
the same OH and temperature
(Spivakovsky
et al.,
1989) the integrated
with CH3CC13 concentrations. ing lifetime
fields
are used in the complete
loss correctly
includes
The 3-D CTM simulation
CTM
simulation
all correlations
of CH3CC13
of OH and temperature
showed that the standard OH field (with a result-
of 5.5 yr) and the OH field scaled by a factor of 0.75 (with a lifetime
of 7.1 yr) bracket
the
observations. This range, however, does not include uncertainties in the observations (i.e., absolute calibration) or in the sources. The observed seasonal cycle of CH3CCI3 in the southern hemisphere is not a direct measure
of the absolute
confirmation
OH concentrations;
of the integrated
Such comparisons
emphasize
and they are independent in CH3CC13.
It is difficult
seasonal
however,
variation
the mid-latitude
of absolute calibration
to find other globally
its accurate
of the modeled
photochemistry
simulation
in the CTM provides
OH fields in the southern
which has the largest
seasonal
some
hemisphere. variations,
and sources because they depend on the relative (%) changes
distributed
trace gases with well defined
sources
and trends that can
be used to test global OH concentrations. For example, Derwent and Volz-Thomas (AFEAS, May, 1989; Volz et al., 1981) have used carbon monoxide, both _4CO and _2CO, to test and recalibrate the OH fields in their 2-D model. Another possibility, trends
and sources.
stantaneous
Data for HCFC-22
trend (N/S = 89/77 ppt,
nificant uncertainties
exist currently
HCFC-22
(CHF2C1) has limited data on hemispheric
abundances,
are sparse and barely able to define the hemispheric + 6.5 ppt/yr in 1985, see NASA/WMO,
for the absolute calibration
and atmospheric
ratio and in-
1986). Furthermore, emissions
sig-
of most HCFCs.
HCFC-22 is used as an intermediate chemical in the production of other compounds, and thus its release is only a fraction of production. Recent estimates of HCFC-22 emission (130 Gg/yr in 1985, M. McFarland, personal current
communication) atmospheric
It is not possible from first principles,
are twice as large as previous
budget
at present
to put a formal
or from constraints
the OH fields is chosen
values,
from the limited observations
"one-sigma"
and are now barely able to reconcile
accuracy
using the methyl chloroform
to be 1.3 and is applied
to the lifetimes 153
the
noted above.
on the OH fields used here, budget.
for HCFCs
The uncertainty in Section
5.
either
factor for
TROPOSPHERIC HYDROXYL 4. SENSITIVITYOF HCFCLIFETIME
TO GLOBAL
We use the 4-D fields of OH and temperature relative to another.
Specifically,
DISTRIBUTION
to understand
how to predict the lifetime
how can the lifetime of one species
be scaled to another
of one species with a different
spatial-temporal distribution and loss rate? Idealized tropospheric distributions are used to examine the sensitivity of HCFC lifetime to (a) the temperature dependence of their reaction rates with OH, (b) large interhemispheric cycles
gradients,
(c) enhanced
concentrations
in the boundary
layer near sources,
and (d) seasonal
in concentration. a. Sensitivity
to rate coefficient:
k = A x exp(-B/T)
Two species, X and Y, with the same global distribution and with rate coefficients for reaction with OH that differ only by a constant factor, k(OH + X)/k(OH + Y) = constant, will have lifetimes that scale inversely
by the same factor. In most cases, however,
the rate coefficients
have different
temperature
pendence, B, or pressure dependence (as in the case of CO). We investigate the dependence lifetime on values of B ranging from 0 to 2300 K, by integrating the loss for an atmospheric is uniformly distributed throughout match the CH4 rate, k = 2.3E-12
The integrated
de-
of HCFC tracer that
the troposphere and stratosphere. The A coefficient was selected x exp(-B/T) cm 3 s-l, and stratospheric losses were not included.
global loss rates are given in Table 4a; lifetimes
range
to
from 81 yr (B = 2300 K) to
0.02 yr (B = 0 K). In Figure 1 we show the error associated with predicting the lifetime by scaling to a reference lifetime (9.42 yr at B = 1700 K) using an appropriate temperature in the ratio of reaction rates. This scaling temperature
is not necessarily
also the shift in the reaction-weighted
the mean temperature
mean OH as a function
of reaction
of the OH losses,
but includes
rate (see Section
2 and Table
2). The optimal temperature for scaling the lifetimes is 277 K, and the resulting errors are less than 2 % over the range 800 K < B < 2300 K. Use of a temperature 10 K warmer or colder yields errors in the lifetime of order K) activation
10% when scaling the reference
b. Sensitivity HCFCs
case (B = 1700 K) to greater
(2300 K) or smaller (1000
energies.
to interhemispheric
released
predominantly
lish a global distribution
gradient
from industrialized
countries
similar to that for CFCs (see Prather
in the northern
mid-latitudes
et al., 1987). The north-to-south
will establatitudinal
gradient will have an interhemispheric absolute difference about equal to one year's emissions, and higher concentrations will build up over the presumed continental sources at mid-latitudes. The sensitivity of HCFC
lifetimes
to their interhemispheric
fields (and temperatures sumes a uniformly includes
doubling
gradient
will depend
on hemispheric
in so far as they affect the rate coefficients).
distributed
tracer with OH reaction
the abundance
in either hemisphere
rates appropriate uniformly.
concentrations
of CO in the northern
hemisphere
(reducing
of 03 and NO x. 154
The base case described
in the OH above as-
for CH4, and the perturbed
Results
factor of 2 asymmetry in the HCFC distribution, the lifetime changes OH loss is about 9% greater in the northern hemisphere. Spivakovsky
asymmetries
case
are shown in Table 4b. For a
by only 1.5%. Thus the effective et al. (1989) note that the higher
OH) are more than offset by the higher levels
TROPOSPHERIC HYDROXYL Table4. Lifetime for speciesx against troposphericOH a. Sensitivity
to rate coefficient
A (cm a s-1)
B (K)
2.3E-12 2.3E-12 2.3E-12 2.3E-12 2.3E-12 2.3E-12 2.3E-12
b. Sensitivity
k(OH + X) = A/exp(-B/T)
2300 2000 1700 1500 1100 500 0
to interhemispheric
2:1 1:1 1:2 to boundary
81.2 27.7 9.42 4.58 1.08 .120 .019
lifetime
layer enhancements lifetime
(global) (global, land) ( > 30°N) (>30°N, land) (>30°N) (>30°N, land)
to seasonal
(yr)
9.42 9.33 9.35 9.42 9.41 9.37 9.33
none
d. Sensitivity
(yr)
9.28 9.42 9.57
enhancement
+ 10% + 10 % + 10 % + 10% + 100% + 100%
(yr)
ratio
NH:SH
c. Sensitivity
lifetime
cycle lifetime
amplitude
(vr)
9.42 9.43 9.52 9.97
none _+1% _+10% _+50%
Except where noted X has a uniform mixing ratio throughout the troposphere and stratosphere, but no loss in the stratosphere. Default values are k(OH + X) = 2.3x10 -_2 exp(-1700/T), boundary layer defined as 984-850 mbar, and no seasonal cycle. The assumed seasonal cycle is: positive in winter, (DJF >30°N) & (JJA 30°N) & (DJF _5 x 10 -13 cm 3 molecule -1 s-1 under the temperature and pressure conditions in the troposphere. The lifetimes of the CF2C1 and CFCI2 radicals will then be 5 x 10 -13 cm 3 molecule -1 s-1 at the temperatures and pressures leading to a lifetime of the CF3CHF radical of -Cz haloalkyl radicals are expected to
be closer to the high pressure limit under these conditions and, based upon the data in Table 2, the alkyl and haloalkyl radicals will have bimolecular rate constants for reaction with Oz of > 5 xl0 -13 cm 3 molecule -_ s-l throughout the troposphere. Since the 02 concentration in the troposphere is _> 10 's molecule cm -3, the lifetime of the alkyl and haloalkyl radicals are 5x10"t3
Anastasiet al. (1978)
(298 K) CF30_
2.7x10"29(T/300)'(5±2)
9x10-_2(T/300)'(0.7±1)
0.49
7.6
CF2C102 CFCI202 CCIjO2
4.0x10-29(T/300)'(5±2)
1.0xl0-t_ (1"/300)'(0.7±1)
0.45
8.4
11
IUPAC(1989)
5.5x10-29(T/300)'(5±1)
8.3x]0-12(T/300)-(0.7±1)
0.42
7.1
9.0
IUPAC(1989)
9.2x10-29(T/300)'(6±2)
1.5x10 -tt (T/300)-(0.3±1)
0.32
12
14
IUPAC(1989)
a Calculatedfrom fall-off expressions. b Assumedto be erroneously 10wdue to neglect of absorption of RO2NO
2 products.
194
9.6
IUPAC(1989)
DEGRADATION these reactions are in the fall-off regime between second- and third-order and this is in agreement
with the thermal
decomposition
MECHANISMS
kinetics below atmospheric
data for the peroxynitrates
(IUPAC,
pressure, 1989; see
below). The available limiting low- and high-pressure rate constants ko and koo and the broadening factor F (at 298 K) are given in Table 4, together with the calculated rate constants at 300 K and 760 Torr total pressure constants
and at 220 K and 100 Torr total pressure. for the reactions
of the C1 alkyl peroxy
Under
tropospheric
and haloalkyl
conditions
peroxy
radicals
the bimolecular
rate
with NO2 are within a
factor of _2 of the high pressure rate constant k_o, and the rate constants for the C2 haloalkyl peroxy radicals will be still closer to the high-pressure limit. From the data given in Table 4, the rate constants koo for the reactions
of RO2
radicals
with
koo(RO2+
approximately These
independent
reactions
of temperature
of the alkyl peroxy
form the alkyl and haloalkyl 1980; Reimer
NO2)
and Zabel,
are,
NO2
---1.0 x 10 -l_ cm 3 molecule -1 s-I over the range 200-300
and haloperoxy
peroxynitrates
radicals
(Niki et al.,
I978,
K.
with
NO2
I979;
proceed
Edney
et al.,
solely by addition I979;
Morel
to
et al.,
1986). M RO2+
NO2
_
ROONO2
C. Reaction with HO: Radicals. Absolute rate constants for the reactions of alkyl peroxy and haloalkyl peroxy radicals with the HO2 radical are available only for CH302 and C2H502 , and these data are given in Table 5. The IUPAC
(1989)
recommended
rate constant
expressions
for these reactions
are k(CH302
+ HO2) = 1.7 x 10 -13 e l°°°/T cm 3 molecule "1 s -1 (4.9 x 10 -12 cm 3 molecule -i s-_ at 298 K) and k(C2HsO2 +
HO2)
=
6.5 x 10 -13 e 65°/T cm 3 molecule -1 s-1 (5.8 x 10 -12 cm 3 molecule -_ s-1 at 298 K). The meas-
ured rate constants
for these reactions
are independent
rate constants for all RO2+ HO2 reactions rate constant of k(RO2+
HO2)
_
of pressure
(IUPAC,
1989). Assuming
are similar to those for these two reactions,
that the
a room temperature
5 X 10 -_2 cm 3 molecule -1 s-1 at 298 K
and k(ROE+
HO2) _ 3.4 xl0 -13 e s°°/T cm 3 molecule "1 s-1
has been recommended by Atkinson (1989a) for all alkyl peroxy radicals. Clearly, a much wider data base is necessary to test this assumption since, for example, Niki et al. (1980) have obtained evidence from a product
study of the C1 atom reactions
with CHaCI and CH2C12 that the room temperature
constant for the reaction of the HO2 radical with CH2CIO2 is significantly HO2 radical reaction rate constant for the CHC1202 radical. These reactions
have been assumed
to proceed ROE+
by the pathway.
HO2 _ ROOH 195
+ O2
rate
slower than the corresponding
DEGRADATION MECHANISMS Table5. Absolute
rate constants for the reactions of alkyl peroxy (RO_) radicals with the H02
radical
10 lz x k ROz"
(cm 3 molecule"
CH302
CzHsO2
(K)
Reference
8.5 --+ 1.2 6.5 + 1.0 3.5 _+ 0.5
274 298 338
Cox and Tyndall
3.5 a
298
McAdam Kurylo
et al. (1987)
6.8
_+ 0.5
228
Dagaut
et al. (1988a)
5.5
_+ 0.3
248
4.1
+ 0.3
273
2.4 2.1
+ 0.5 _+ 0.3
340 380
5.4
+ 1.1
300
6.8
_ 0.9
303
6.3
_ 0.9
7.3 6.0
Jenkin
et al. (1988)
295
Cattell
et al. (1986)
_+ 1.0 + 0.5
248 273
Dagaut
et al. (1988b)
5.3
+ 1.0
298
3.4
+ 1.0
340
3.1
+ 0.5
380
Jenkin et al. (1988) observed
et al. (1987),
the additional CD202
contributing
et al. (1987)
298
However,
with this channel
(1980)
_+ 0.4
value as cited by Kurylo
and postulated
s")
2.9
a Revised
HO2 radical,
at T
"-40%
+
Dagaut
the formation reaction HO2
--"
et al. (1988a)
and Jenkin
of HDO from the reaction
et al. (1988).
of
CD20
_
with the
pathway, DCDO
of the overall
+ HDO
reaction
+ 02
at room temperature.
D. Reaction with Alkyl and Haloalkyl Peroxy (RO2) and Acyl Peroxy (RCO_) Radicals. The available absolute rate constant data for the self-reactions of alkyl and haloalkyl peroxy (RO2) radicals and for their reactions with other alkyl peroxy and acyl peroxy radicals are given in Table 6. Clearly, the majority of the data concern the self-reactions of the alkyl peroxy radicals, with the only data for cross-combination reactions
being for the reactions
Since the tropospheric will be low (because
of the CH30_ radical with tert-butyl
peroxy
and acetyl peroxy
radicals.
formation rates of the haloalkyl peroxy radicals being dealt with in this assessment of the low rate constants for the reactions of the OH radical with the HCFCs and 196
DEGRADATION
HFCs
in question),
is expected
self-reactions
that the dominant
with will
be the CH30_
reaction
of the
RO_
CH30_
radical
an uncertainty
Table
6.
Rate
of _ _+ a factor constants,
haloalkyl
k
peroxy
=
with which
data
RO2
radicals
C2H502
Ae -B/T, for the radicals
C2H502
CH3CH2CH202 (CH3)2CHO2 (CH3)3CO2
+ (CH3)2CHO_
gas-phase
with
RO;
CH30
and
combination RC03
+
These
CH2CICH202
reactions
of RO2
+
RIR2CHO2
reactions al.,
of CH302,
1981,
room
(b) not being 1982;
C2H_O2,
Anastasi
temperature
rate
< 0.1.
For the reaction
Parkes
(1981)
at around significance RO2
also
room
radical
accessible
constant
1983;
11_v +-IO0 3oo
0.86
IUPAC
(1989)
3
IUPAC
(1989)
0.01
IUPAC
(1989)
0.00019
Kirsch
et al. (1978)
+ 0.5
Parkes
(1975)
35.7
+ 5.7
Dagaut
et al. (1988c)
2200
+ 300 4775
+
170
ratios
proposed
temperature.
that
IUPAC (1989)
-1020
3.1
-735
+ 95
37.8
+ 4.5
Dagaut
et al. (1988d)
3.3
-700
+ 100
30.7
+ 6.5
Dagaut
et al. (1988d)
IUPAC
(1989)
for the self-reaction
can proceed _
R3R4CHO2 for tertiary
ka/k
_
RO2 1989).
radicals.
reaction
radical,
reactions. 197
channels
+ +
radicals
(c)
02
and Parkes,
and secondary
k = ka + kb + radical, were
concluded
that reaction
1981;
(1975)
product
data
Niki
_0.5,
with
and Kirsch
(a) and (b) above, pathway
for the self-
RO2 radicals,
k c) are both
Parkes
pathways
and further
(b)
02
data are available
(Kirsch
For the primary
(a)
+ 02
RaR4CO
Product
with the CH302
Niki et al. (1980)
of the CHC120_
+
RIR2CHOOCHR3R4
and kb/k (where radical
reaction
+ R3R4CHO"
RIR2CHOH
and (CH3)3CO_
IUPAC,
by the
RIR2CHO" _
the operative
However,
Reference
1.1
radicals
of the (CH3)3CO2
and
1.2
(CH3)2CHO2
et al.,
alkyl
3.6
R3R4CHO2 +
of
-220 ± 220
+ R3R4CHO2
RIR2CHO2
channel
reactions
110
R2R2CHO2
with
K
1.7
CH3CO3
combination
for the
radicals
1.0
+ CHEFO_
_
will react
constant
l0 is x k (298 K) (cm 3 molecule "1s "1)
1700
+ CHEC10_
CH2FO2
It
B (K)
16
+ (CH3)3CO_
+
radicals
a rate
-_ s -_ at 298
+ CH3CH2CH202
CH2C1CH202
peroxy
6) suggest
importance.
of
CH_O_ + (CH_)_CO_ CH2C10_
haloalkyl
(Table
) _ 2 x 10 -_3 cm 3 molecule
CH302
+
will be of minimal
these
available
1013 x A (cm 3 molecule -1 s"a) +
radicals
of 5.
(ROE)
Reaction CH302
other
CH302
peroxy
radical
and the limited with
+
haloalkyl
or RCO_
radical,
k(RO2
with
of these
MECHANISMS
with
et the kc and
ka = kb
(b) was of minor
are required
for these
DEGRADATION
MECHANISMS
For the self-reaction of the tert-butyl peroxy radical, Kirsch and Parkes (1981) = 0.12 at 298 K, with this ratio decreasing rapidly with increasing temperature. 4.3.
Reactions
of Alkoxy
and Haloalkoxy
unimolecular
that kc/k
(RO') Radicals
For the CI and C2 haloalkoxy radicals involved in the tropospheric degradation and HFCs considered in this article, the reactions of concern are with 02, RIR2CHO"
determined
+ 02
-*
RIR2CO
+
reactions
of the HCFCs
HO2
decomposition, R1RECHO
and reaction
--' RI
+ R2CHO
with NO and NO2. RIR2CHONO RIR2CHO"
+ NO _
R_R2CO
+ HNO
RtR2CHONO2 RIR2CHO"
+
NO2
_ A. Reaction
with 02. Absolute
only for the CH30",
rate constants
C2H50" and (CH3)2CHO"
Table 7. For the methoxy Wantuck
RIR2CO
< 300 K (the Arrhenius
plot exhibits
k(CH30" This recommended (1987) and IUPAC
for the reactions radicals,
radical the rate constants
et al. (1987) are in good agreement,
of Gutman
curvature
of alkoxy radicals
and the rate constant
and Atkinson
marked
+ 02)
+ HONO
et al. (1982),
(1989a)
s-t and 7.2 x 10-14 e -1°8°/T cm 3 molecule -1 s-I, respectively.
(Atkinson,
1989a). Similarly,
with a preexponential
et al. (1985)
and
that for temperatures
> 500 K).
is that of Lorenz et al. (1985), and is similar to the NASA of k(Cn30" -t- 02) = 3.9 x 10 -14 e -9°°/T cm 3 molecule -1 Combining
al. (1982) at 296 and 353 K for the C2H50" radical with a preexponential s-' leads to + 02)
are given in
= 5.5 x 10 -14 e -l°°°/T cm 3 molecule -I s-_
temperature expression (1989) recommendations
k(RCH20'
Lorenz
recommended
at temperatures
with 02 are available
data obtained
the rate constants
of Gutman
et
factor of 3.7 x 10 -14 cm 3molecule -1
= 3.7 x 10-14 e -46°/T cm 3 molecule -_ s-I
the data of Balla et al. (1985) for the (CH3)2CHO"
radical can be combined
factor of 1.8 x 10 -14 cm 3 molecule -1 s-1 to yield (Atkinson, 198
1989a)
DEGRADATION MECHANISMS Table7. Absoluterate constants,
RO"
k, for the gas-phase reactions of alkoxy (RO) radicals with 02
1015 x k
T
(cm 3 molecule "t s"1)
(K)
Reference
7 x 105
Room
Reference
Carr et al. (1986)
temperature "-'1 x 1014
CFC120' --*COFCI + CI
CC130' -_ COC12 + CI
5335c
_1 x 1014
CHCI20' -# HC(O)CI + CI
_1 x 1014
5940c
253
Rayez et al. (1987)
>3 x 104
253
Lesclaux et al. (1987)
8 x 104b
233
Rayez et al. (1987)
>1 x 105
233
Lesclaux et al. (1987)
2 x 105b
298
Rayez et al. (1987)
> 105
298
Niki et al. (1980)
_1 x 1014
10320c
0.1b
298
Rayez et al. (1987)
CHFCIO' -' HC(O)F + CI
"ol x 10TM
5230c
2 x 106b
298
Rayez et al. (1987)
CHF20' -' COF2 + H
_1 x 1014
17770c
1 x 10"12b
298
Rayez et al. (1987)
CHFCIO' --' COFCI + H
_'1 x 1014
14800':
3 x 10sb
298
Rayez et al. (1987)
"_1 xl014
14900c
2 x 10-Sb
298
Rayez et al. (1987)
_1 x 1014
13340c
4
298
Rayez et al. (1987)
",'1 x 1014
14540c
6 x 10"Sb
298
Rayez et al. (1987)
CH2CIO"
HCHO + C1
4880c
7 x 104b
_
CH2CIO'
HC(O)C1 + H
_
CHCI20" -_ CH2FO'
_
COC12
+
H
HC(O)F + H
X 10 6b
a High-pressure limits. b Calculated from cited Arrhenius expression. c Calculated.
Gillespie
et al. (1977),
(c) For the CHCI20'
Suong and Carr (1982) radical,
decomposition
and Withnall
and Sodeau
by C1 atom elimination
(1986).
dominates
over reaction
with 02
at room temperature and atmospheric pressure. However, this may not be the case at the lower temperatures and 02 concentrations encountered in the middle and upper troposphere. In contrast, decomposition of the CH2C10" radical is slow and the reaction with 02 CH2CIO"
+ 02
-_ HC(O)CI 200
+ HO2
DEGRADATION MECHANISMS dominates
at room temperature
and is expected
For the C2 haloalkoxy (a) For
that decomposition
(b) For
higher
Thus, for example,
pressure
Sanhueza
(X = F, CI and/or
by Sanhueza
haloalkoxy
radicals
CF2C1CCI20" CCI3CF20"
CF2C1CF20"
conditions,
the important
that:
(presumably) energy
pathways
that reaction
are sufficiently
en-
with 02 will dominate.
H), the C-F bond dissociation
that C-C bond cleavage
energy is
occurs.
and Heicklen (1975) and Sanhueza et al. (1976), the dominant
CFC12CFC10"
For tropospheric
concluded
H), the decomposition
(X = F, C1 and/or
as discussed
et al., 1976; Niki et al., 1980),
conditions.
et al. (1976)
than the C-C bond dissociation
for the following
of air (Sanhueza
for all tropospheric
does not occur, and hence it is expected
radicals
CX3CF20"
sufficiently
reactions
radicals,
radicals
CX3CH20"
dothermic
and atmospheric
to totally dominate
are _ _
CFC12C(O)F
+ C1
CF2CIC(O)C1
+ C1
"-* COF2
+
(_C13
-_
+
CF2C1
COF2
parameters
are the rate constant
ratios for the reactions
of
the alkoxy and haloalkoxy radicals with 02 and their various decomposition pathways. It is anticipated that the rate constants for these processes will depend on their heats of reaction [since (Table 8) the preexponential factors for the various decomposition pathways appear to be reasonably similar at "_1 x 1014 s-X]. Since in most cases the heats of formation of the reactant alkoxy and haloalkoxy radicals are not known
with any certainty,
the reaction
products
it is possible
for the reactions
that the differences
between
the summed
of the various alkoxy and haloalkoxy
radicals
heats of formation
of
can be used as a tool
in deciding the relative importance of these reaction pathways. Table 9 gives examples of the summed heats of formation of the products for the various reactions of the ethoxy, 2-butoxy, CH2CIO" and CH2C10" radicals. These data in Table 9 show that the H atom elimination pathway is the most endothermic decomposition route (being relatively tent with Table
close to the C1 atom elimination
The differences in the heats of reaction,/[AHO2 reaction to the nearest kcal mol -t) are then: C2H50", 45; 2-butoxy, temperature reaction
pathway
for the CH2CIO" radical,
consis-
8).
and atmospheric
pressure
with 02 (Carter and Atldnson,
AHdecomposition]!
42; CH2CIO
of air, the removal 1985); 2-butoxy,
processes
reaction
= A(AH), in kcal mol -_ (rounded , 48; and CHCI20", 30. At room
of these RO" radicals
with 02 and decomposition
are: C2H50", by C-C bond
cleavage in an approximately 60%/40% split (Carter and Atkinson, 1985; Atkinson, 1989a); CH2C10", reaction with 02 (Niki et al., 1980); and CHC120", CI atom elimination (Niki et al., 1980). Thus, as expected, there is a relation between the reaction pathway and the difference in the heats of reaction between the pathways. For A(AH) >43 kcal mol -t, reaction with 02 dominates, while for A(AH) 1 x 105 (233K)
Lesclaux et al. 1987
> 3 x 104 (253 K)
Lesclaux
et
al. 1987 CCIF20
--_ CF20
+ CI
> 7x
105 (298K)
Carr et al. 1986
Reactions
of hydrochlorofluoroethoxy
radicals
Important information concerning the ways chloro- and chlorofluoro-ethoxy radicals react or decompose, can be obtained from studies of the chlorine atom-initiated oxidation of chloro- and chlorofluoroethylenes which proceeds by a long chain, free radical process. These reactions have been extensively studied, mainly by the groups of Shumacher, Huybrechts and Heicklen (see Muller and Schumacher, 1937a,b; Schumacher
and Thurauf,
1941; Huybrechts
and Meyers,
1966; Huybrechts
et al. 1965; Sanhueza
Meicklen, 1975b,c,e) and the results have been collected by Sanhueza et al. in a review these data, some general rules can be drawn on the reactions of such radicals. i - Chlorine
atom detachment CX3CYCIO
(XandY
--*
CX3CYO
= H, ClorF) 224
+ C1
(1976).
and From
DEGRADATION MECHANISMS This type of reaction
always
occurs preferentially
if Y = C1 or F, independently
of the nature of the
CX3 group. For example, CCI3CC120, CHC12CCI20, CC1FzCC120, CCI2FCCIFO, CCIF2CC1FO cals essentially undergo this type of reaction. By studying the photooxidation of methyl chloroform, son et al. (1984),
showed
that the radical CH3CCI20
also dissociates
radiNel-
in this way.
ii - C-C bond cleavage CX3CX20 This reaction
always
occurs
for radicals
--' CX3 + CX20
of the type
independently
CX3CF20,
of the nature of
CX
3.
The situation is not as clear for CX3CHFO or CX3CHC10 radicals, since they can either undergo a C-C bond cleavage or react with oxygen. It seems however that the C-C bond cleavage is the most favourable process
for these radicals.
mosphere
of air,
CH2CICHC10
In a study of CI atom sensitized
Spence
and Hanst
and CH3CHCIO
essentially
Small amounts of acid chlorides oxygen.
The same conclusion
ethylenes
(Sanhueza
Apparently,
(1978)
have, however,
was reached
preferentially
gen seems to be a minor process
--_ CX3CXO
for CX3CHXO
radicals.
relevant
to this review.
reaction
for C2H50,
iv - Oxidation
of the
resulting
radicals
from the reaction oxidation
with
of chlorinated
react in the same way.
has not been observed.
product
HO2
However,
of the type CX3CH20,
it will be considered
The rate constant
taking into account
yielding
for this reaction
as a possible
is assumed
the effect of the halogen
radical is one of the major uncertainties
This radical
in laboratory
the elimination
+
to be
atom on the
radical
CF30
of the CF30
of perfluorocompounds.
be important
as a result of the C-C bond cleavage.
been detected,
occurs in the cases of radicals
in the compounds
knowledge,
in one at-
CHC12CHCIO,
This has been shown for CC13CH20 (Nelson et al. 1984; Sperce (Sperce and Henst, 1978). As shown above, the reaction with oxy-
one tenth of the equivalent H atom reactivity.
containing
ethanes,
CC13CHC10,
with oxygen
this reaction
The oxidation
chloride
that CX3CHFO
from CX3CCIHO
a halogenated acetaldehyde molecule. and Henst, 1978) and for CH2CICH20 channel
of chlorinated
in the study of the C1 atom sensitized
et al. 1976). It can be expected
CXaCXHO
Obviously,
oxidation
that the radicals
yield formyl
CX3CC10
the CI atom detachment
iii - Reaction
showed
is formed
systems
in the degradation
appears
to be CF202.
of an F atom either thermally
in the atmosphere
in the mechanism
of CF3 via According
or by reaction
CF202
to current
+ M
CF30
+ 02 -'* CF20
-_
CF20
+
F + M
AH ° =
+ 36 kJ mo1-1
+
FO2
AH ° =
+ 42kJmo1-1
225
and the major
C-
thermochemical
with 02 is too endothermic
:
CF30
of degradation
to
DEGRADATION MECHANISMS Accordingly
it has been hypothesized
that heteregeneous
of CF20 in laboratory systems. It is important ways may occur in the atmosphere. 6 - Photochemical Halogenated
therefore
reactions to establish
whether
for the formation
other homogeneous
path-
reactions
hydroperoxides
Information on the photolysis of halogenated hydroperoxides, photolysis is likely to be rather
hydroperoxides is sparse. By analogy with the alkyl slow and to occur via dissociation of the central O-O
bond leading to the same alkoxy radical as that produced by reaction NO. For modeling purposes, it is recommended to use J(CH3OOH) CX_OOH Carbon',/I
are responsible
+ hv --' CX30
of the original peroxy for the reaction :
radical
with
CFCIO
and
unaffected
by
+ OH
Halides
The absorption
spectra
of the carbonyl
halides,
CX20,
have been determined
for CF:O,
CC120 (Baulch et al. 1980). The molecules absorb only in the deep UV and are virtually sunlight in the troposphere. Photolysis leads to elimination of a halogen atom : CX20
+ hv ---, CXO
+ X
The fragment radical CICO is unstable with respect to decomposition to CI + CO and the same is probably true for FCO, although the thermodynamic stability of this radical is still uncertain. The photochemistry
of CHXO (X = F or C1) has been investigated
in the case of CHFO (Okabe,
1978).
It appears that substitution of halogen on the carbonyl carbon atom, X-C = O, has the effect of shifting the n_Fl* electronic absorption in the C = O group to higher energies (blue shift in wavelength), thus reducing
the rate of photoabsorption
ation rates are therefore
in the lower part of the atmosphere
likely to be reduced in consequence,
Although CX3CHO, CX3COCX3,
Photodissoci-
although the effect may be modified by changes
in the quantum yields, which are not known. These arguments carbonyls of the type CX3CXO. Halogenated
quite dramatically.
are also expected to apply to fully halogenated
aldehydes there there
is little information is considerable
which
photolyse
on the photochemistry
information
of the halogenated
on the photochemistry
in the near UV following
n-q-I*
aldehydes
of the halogenated
excitation
(Macket
of the type ketones
and Phillips,
e.g. 1962).
Since the absorption by aldehydes in the corresponding near UV band is also an n---,I-l*,absorption of fully halogenated ketones, (CF3)2CO, (CF2C1)2CO and (CC13)2CO, is shifted up to 20 nm to the red, making these molecules photodissociation
more strongly
absorbing
in the solar UV troposphere.
near 300 nm are 0.8 (Whytock
and Kutsche,
Moreover,
the quantum
1988), i.e. substantially
simple aliphatic ketones. Comparing this analogy for aldehydes of the type CX3CHO, rather rapid photolysis of these compounds according to the reaction : CX3CHO
+
hv---, CX3 + HCO 226
higher
yields for than for
we may expect
DEGRADATION MECHANISMS However,
at short wavelength,
another
photodissociation
CX3CHO A reasonable
approximation
H + HCO channels A novel process C-C bond
rupture
+ hv --* CHX3
this process
ketones
+ hv _
may be open for the (slower)
of OH with halogenated
For the hydroperoxides,
photolysis
of a C1 atom rather
than
CX3CHO
+ OH
CX3OOH
+ OH _
:
+ C1
the -CH0 group)
--* n20
+
H20
through
OH at-
CX3CO
to the C atom (relative
For the rate coefficients
can degrade
+ CX3OO
due to the deactivating
of 2 to compensate
type carbonyls
and aldehydes
the H-atom attached
by a factor
+ C1
of CX3CXO
hv ---' CX2CXO
+
peroxides
than the Hoo atom,
C_ and C2 fragments. H202 reduced
is the elimination
CF2CICOCF2
Halogenated hydroperoxides and aldehydes (containing tack. The reactions can be written as follows :
to be abstracted
via the
e.g.
CX2CICXO
7 - Reaction
+ CO
in the atmosphere.
in the chloro-substituted
CF2CICOCF2C1 This channel
may occur :
would be to use the same J value as for HCHO photodissociation
for modelling
observed
pathway
to the peroxy
effect of the nearby
the preferred
estimates
for the lower number
link) are less likely
halogen
atoms in both
are those for reaction of abstractable
of OH
H-atoms.
+
The only
halogen substituted aldehyde for which the rate coefficient for OH attack appears to have been measured is chloral, CCI3CHO, derived from the photo-oxidation of methyl chloroform (Nelson et al. 1984) for which a value of 6.2 x 10 -12 cm3molecule-ts -_ was obtained at 298 K. In the same study, the rate coefficient for OH attack
on acetyl chloride OH
was determined of H abstraction. fluorocarbonyl
:
+ CH3CCIO
--_ H20
+ CH2CCIO
to be 7.2 x 10 -_4 cm 3 molecule -_ s-t showing Fluorine
substitution
is also expected
that the C-CIO group also reduces
to show a similar deactivating
the rate
effect in analogous
compounds.
The rate of the HCFO
and HCC10
molecules
with OH is unknown
OH + HCXO A value of approximately vation by the halogen
1 x 10-t2 cm3molecule
-, H20
+ CXO
- _s-_ is estimated,
atom for H-abstraction. 227
:
taking into account
the effect of deacti-
DEGRADATION
8 - Rainout_
MECHANISMS
washout
All oxygenated
and dry deposition
processes
secondary products from the oxidation of HCFC's
aldehydes, carbonyl halides and acid halides (e.g. CX3CFO), in the precipitation
elements
and Henry's
law constants
precipitation
elements
and also by dry deposition for these gases is required
for the carbonyl
and CFC's,
hydroperoxides,
halogenated
will be subject to removal by solution/hydrolysis
at the earth surface.
Knowledge
in order to assess the importance
halides CCI_O, CFC10 and CF20.
of the solubility of removal
Since these molecules
in the
are very
stable towards gas phase removal, removal by wet and dry deposition probably has an important role in determining their atmospheric lifetime. Recent estimates of the lifetime of phosgene, based on measured concentrations
and the estimated
source
strength
(Wilson
228
et al. 1989), are about 2 months.
DEGRADATION
APPENDIX
III (R.A.
COX
Recommended
AND
R. LESCLAUX)
rates
coefficients
for modelling
atmospheric
MECHANISMS
degradation
of hydrochlorofluorocarbons A schematic in Figure reactions marised
diagram
1. In order
illustrating to formulate
and 4 photochemical in Table
the degradation
A and
the basic
reactions
pathways
chemistry,
are required.
for the photochemical
OH
+
of a typical
knowledge
hydrochlorofluocarbon
of the rate
The best estimates
parameters
HCFC
in Table
coefficients
B.
,/ K-1
[
CX3CHXO0
_
+NO_
I
6:1
_j+h
J
CX3CHXO
Peroxynitrate
/
I Hydr°per°xide rv
K5
:X CI 1_
Minor
products
Figure 1. Tropospheric
shown
Degradation
in "broken"
Pathways
boxes,
for typical
229
(X=H} +0__)
major
products
CFC substrates.
for 10 thermal
of the rate coefficients
+ 0 I'D1
HCFC
is shown
in "full"
boxes
are sum-
DEGRADATION MECHANISMS _v ON+
()3_X2)
u_
b tr,
LL
:OH
+ ()3
_ X3
to-,
¢5 --
"O tOO _7 ¸
L'
0_ ()H3
LL
_ _3
_r'
_
3
o.
_
T
+ HO
E_
J
_9 "1"
+ _,7
6'
O :OH+OX3
_4
_Xo_rO+O_[
©
o
+
+
+
q
© , ;i_¸
q
,-e
C co ¢-
T
©
5..
u_
c
g_
b
E
+
>
d
O
E
:OH
+ ()HD
_XD_rO+OH
r" 0
¢,
1,3 + OXDt
X3
_ OH
o ,-r.
tO
_v
OrXD+
_XD*--
.C = O + HzO + 02 via formation entirely
ruled out. The products, 11987; CODATA,
Reactions
Involving
The atmospheric
of an adduct
the possibility [ROOOOH]
haloalkryl hydroperoxides,
to react further with HO radicals to regenerate Report,
However,
evidence
of an alternative
complex
are intermediate
formation
products
for the
mechanism has not been
which
are likely
ROO radicals, in analogy to the reaction of CH3OOH
(NASA
1982, 1984).
RO Radicals reactions
of the haloalkoxy
been carried out at room temperature
RO radicals are less well established.
and atmospheric
Simonaitis
studies have
pressure of air for the following RO radicals; CH2CIO
+ 02 --' CHCIO + HO2 (Simonaities and Heicklen, --* CHCIO + CI (Simonaitis and Heicklen, 1979; CF3-xCIx-_O + C1 (1 _ 6.0 (Hybrechts
and Meyers,
1966; Bertrand et al., 1968); CH2C1CC120
_ (CH2CICCIO
+ C1)/(CH2C1
+ CC120)
is extremely
25 kcal/mol),
fast under all tropospheric reaction
(2')
R'CH2 for less than 0.1% (R'
b. ROJRO
(i) RO2/NOx
high R-O2 bond
and RO2 is the only form in which
interactions
+ 02 _
Due to the relatively
between
R exists in
R and 02 leading to an unsaturated
R'-H = CH2 + HO2
= CH3) of the overall
reaction and can safely be discarded
for the simpler
conversion
Unlike step (a), the conversion on the ambient conditions.
mechanism
of alkylperoxi
radicals to alkoxi radicals
- step (b) - depends
interactions:
In the continental boundary oxides are normally present with NO, viz. (3)
Alternative
RO2 (+M)
conditions.
(2) is not reversible
perceivable levels in the troposphere. HC and HO2, viz.
account HC's.
_
radicals, viz.
layer as well as in the upper troposphere/lower stratosphere, sufficient nitrogen for the alkylperoxi radical chemistry to be dominated by the fast reaction
RO2 + NO _
254
RO
+ NO2
DEGRADATION MECHANISMS The rate constants
for this process
n-C3H7 and i-C3H7 (Atkinson
at 298 K are of the order
et al.,
1989). However,
tween RO2 and NO may also proceed (3') The importance and 4.4% Under
of this process
general application initrates,
where
increases
with chain length and amounts
to
©
0.4
®_=
0.3
CH3CCl3
HCFC-123 HCFC-124
0.2
HCFC-141b
0.1
!
0 0
10
1 20
30
40
50
Year
Figure 25. Calculated Time-Dependent Emission of Halocarbons. (LLNL l-D).
Relative
372
Chlorine
Loading
Following
a Step
Change
in
STRATOSPHERIC OZONE
CFC-12
CFC-115
0
50
100
150
200
250
Time
300
350
400
450
500
(Yr)
Figure 26. Calculated Time-Dependent Relative Emission of Halocarbons. (DuPont l-D).
373
Chlorine
Loading
Following
a Step
Change
in
STRATOSPHERIC OZONE 8. ACKNOWLEDGMENTS The authors are grateful vironmental
Acceptability
for the support
received
Study (AFEAS).
for this work from the Alternative
Additional
funding was provided
Allied-Signal Corporation, Atochem, E.I. du Pont de Nemours Chemicals and Polymers Limited, and Montefluos SPA. Work at AER, Inc. is also supported Atmospheric Theory and Data Program Aeronautics and Space Administration, Energy (W-7405-ENG-48).
by the National
En-
by the following companies:
& Co., Hoechst
Aeronautics
Fluorocarbon
Aktiengesellschaft,
and Space Administration,
ICI
Upper
(NASW-4080). Work at LLNL is also supported bv the National as well as being under the auspices of the U.S. Department of
374
STRATOSPHERIC OZONE APPENDIXA: RELATIONSHIP BETWEENFORMSOF ODP It is helpful to look at the various
formulations
tween them. We have chosen our definition release
of a given compound
for ODP and explore
rate of CFC-I 1 at steady state. Subsequently,
ozone change resulting
we showed,
at time t = to a stimulus containing
S(to) [which in this example
gas into the atmosphere]
Properties
In terms of physical specific.
STEADY
STATE
strength
to the ozone column
to a release
change]
of a set mass of chlorine
make the assumption
that the response
to Dive:
g(t) are that:
g(o_ ) = 0 (i.e.,
is species
to the source
that the ratio of cu-
= G(t-to)/S(to)
of the function
within the reacting
corresponds
a constant
equivalent to ODP. The purpose of in order to define the relationship(s)
corresponds
at time to. We furthermore
is linear so that it can be normalized g(t-to)
[which in this example
be-
from the same mass release
based on model exercises,
mulative effects following a one-time input of gases was virtually this section is to examine the background mathematical formulations between the tbrmulations. function
relationships
for ODP to be the column ozone change following
divided by the column
Let G (t-to) be the response
the background
processes,
the response the function
system (atmosphere)
Let us first examine
decays
to 0 at infinite
g(t-to) contains
time),
the results from the transport
and is specific to one set of reaction
the case of a steady-state
response.
If a stimulus
parameters,
and chemistry and therefore
started at time = 0 and held cons-
tant at S = S o until steady state is realized, then the steady-state response is reached the integrated response from all gas released over history and is of the form:
at time T and is
to =T Gss = f So*g(T-to)
dto
to =0 Since by definition
of steady state, it is insensitive
at time, t = - . Thus, Gss can be expressed,
to starting
without
time, so we could have started
loss of generality,
the release
as:
to=T Gss
= f S O * g(T-to)dt o tO
Therefore
if we use the notation
the corresponding
response
=
-_
that Gss-x is the steady
for CFC-I 1, then ODP(ss) 375
state response can be expressed
for compound as:
x, and Gss-11
is
STRATOSPHERIC OZONE ODP(ss)
Gss-x/So-x
=
Gss-11/So-11 or,
T f gx(T-to)dt o -OO
ODP(ss)
=
(A)
T f gll
(T-to)dt o
-00
With a substitution
of integration
variables
of :T-to.
equation
A becomes:
O -f gx(t)dt +oo ODP(ss)
= 0 -f g 11 (t)dt
or,
oo
-f gx(t)dt ODP(ss)
=
0
(B) oO
-f g 11 (t)dt 0
PULSED INPUT Now, let us focus on the ratio of integrated responses to a pulsed input. For a pulsed input of value PS at time to, the integrated resulting effect, GP, on the system over the ensuing period is: oO
GP
= f PS *g(t-to)
dt
to Since PS is constant,
GP becomes:
GP
= PS*
f g(t-t o) dt to
376
STRATOSPHERIC OZONE We can again change the integration variable such that T = t-to and since the values for PS will be the same both in the numerator and the denominator, the ratios of integrated responses reduces to: oo
GP-x
f gx(T) dT 0
(c) oO
GP-11
Which
is the same functional
f g 11 (T) dT 0
form as ODP expressed
by equation
B.
Therefore we have shown mathematical equivalence as long as we have linear relationships between release (stimuli) and ozone chance (response). Real world interpretations as well as model exercises indicate that the relationships
are not exactly linear. Therefore,
discrepancies
to pulsed releases do exist but are caused by the (minor) non-linearities cal round-off errors associated with the numerical models.
377
between ODP and ratio of responses of the phenomena
and/or
numeri-
IX.
Relative
HALOCARBON GLOBAL POTENTIALS
Effects
on Global
Warming
WARMING
of Halogenated Methanes Industrial Interest
and Ethanes
of Social
and
D. A. Fisher and Charles H. Hales E. I. du Pont de Nemours & Company Wilmington, DE Wie-Chyung Wang, Atmospheric
Malcolm K. W. Ko and and Environmental Research, Cambridge, MA
_"
/
/
N. Dak Inc.
EDING
PAGE
Sze
BLAr,_K NOT
FILMED
GLOBAL WARMING EXECUTIVE Halocarbon of the relative
Global Warming environmental
Potentials
SUMMARY
have been defined
effects of halocarbons
the HGWPs of the hydrohalocarbons to a lesser degree on the molecular
and calculated
to be made.
in order to allow estimates
The results presented
depend primarily on the atmospheric IR absorption characteristics.
lifetime
here indicate
that
of the compounds
and
The reduction in HGWP that might be expected due to use replacement of a CFC by a hydrohalocarbon can be estimated by taking the ratio of the HGWP of the hydrohalocarbon to the HGWP of the CFC it would replace.
For example,
± .010)/(3.05)
= 0.085
use application
the reduction ± 0.003.
Of course,
deled chemistry
and dynamics
radical
reactions
to assumed
influenced
by the changes
depending
times,
once better data is available
to be reasonably
values of other radiative
Calculated time-dependent longer
quantities
and their direct effect on the chemical
with the respective
values appear
insensitive
or increase
the relative
uses of CFC-12
by HCFC-134a
of the compound
is (0.26
required
in the
values reported here agree between models reasonably well once accounting is in lifetimes, uncertainties in the values still exist due to the uncertainties in mo-
expect that these values will be updated
The HGWP
in replacing
must also be taken into account.
Although the HGWP made for the differences
hydroxyl
in HGWP
in calculated
Global
robust parameters
for the ultraviolet
reactions
We
and the
since their calculated
values are nearly
gases. The minor shifting of the HGWP values in primarily
lifetimes
their lifetimes Warmings
of these compounds.
compounds.
and therefore
the abundance
relative global warmings for halocarbons
on whether
the Relative
lifetimes
are shorter
asymptotically
in the atmosphere.
are initially on order unity but decrease
or longer than that of the reference approach
the HGWP
gas. At
values.
381
PRECEDING
PAGE
BLA_'K
NGT
FILMED
N92"15447
RELATIVE METHANES
EFFECTS ON GLOBAL AND ETHANES
WARMING
OF HALOGENATED
OF SOCIAL AND INDUSTRIAL
INTEREST
Donald A. Fisher and Charles H. Hales E.I. du Pont de Nemours Wei-Chyung
Wang,
Atmospheric
Malcolm
& Company
K. W. Ko and N. Dak Sze
and Environmental
Research,
_ING
Inc.
PAGE
BLI'.',_K NOT
FILMED
GLOBAL WARMING ABSTRACT The relative potential global warming effects for several halocarbons (CFCs -11, 12, 113, 114, and 115; HCFCs 22, 123, 124, 141b, and 142b; and HFCs 125,134a, 143a, and 152a; carbon tetrachloride; and methyl chloroform) have been calculated by two atmospheric modeling groups. These calculations were based on atmospheric chemistry and radiative convective models to determine the chemical profiles and the radiative CFC-11
processes.
agree reasonably
ences among
The resulting
relative
greenhouse
well as long as we account
results are discussed.
trace gas levels assumed.
Sensitivity
Transient
relative
of relative global
warming
for differences warming
warming
when normalized
between
modeled
to the effect of lifetimes.
values is determined
effects
Differ-
with respect
to
are analyzed.
1. INTRODUCTION A systematic environmental includes the potential effects for rising environmental
evaluation of replacements for fully halogenated chlorofluorocarbons (CFCs) of each replacement chemical on global warming. While the major focus
concerns
centers on the potential effects of long-lived
the role of these gases as contributors
to an enhanced
greenhouse
tion. This concern
is based on the ability of these gases to absorb
'window'
8 and 12/am.
between
First, a brief background The radiative
to establish
and thermal balance
infrared
primarily
surface and atmosphere
ozone,
also needs examina-
radiation
the role of these gases in the 'greenhouse
of planet Earth is established
and visible) solar energy to the Earth's
CFCs on stratospheric
or global warming
in the atmospheric
warming'
by balancing
phenomena.
the incoming
with the outgoing (infrared)
radiation
(UV from
the Earth's surface and atmosphere eventually being lost to space. Infrared energy is partially blocked at many wavelengths by naturally occurring gases such as carbon dioxide, methane, and stratospheric water vapor.
These gases absorb energy at fundamental
contributes
frequencies
characteristic
of their structure.
and is eventually
re-radiated.
tive balance
of the infra-red
cooling process.
Hence, the concern
significantly
impede infrared cooling of the Earth with a decrease in energy loss to space and a corresponding
increase
in the Earth's
The atmosphere
surface
'window'
between
However,
that increasing
change the radia-
CO2 concentration
will
temperature. 8 and 12/am is virtually transparent,
that absorb energy at these wavelengths, tially unimpeded.
Changing gas concentrations
This energy
to local warming
outgoing infrared
radiation
i.e. since few gases are present
passes through
both C-CI and C-F bonds have natural
vibrational,
the atmosphere bending,
essen-
and rotational
excitation frequencies in this infrared frequency range such that CFCs absorb the infrared energy to become very effective greenhouse gases. Their effectiveness as greenhouse gases is accentuated by their long lifetimes. is important
Since functional
to estimate
replacements
of these gases is determined
gases build up higher
tropospheric
tiveness
gases are the infra-red
of energy absorbed
there is yet another
concentrations.
within these intervals
Besides the influence
infrared
energy
in the window
their potential impact on global climate as part of this evaluation.
strated below, the effectiveness as greenhouse
may also absorb
Longer
in determining
i.e. the wave length intervals
lived
the effec-
and the amount
by each molecule.
on the infrared radiative
aspect of the radiative
importance
it
As will be demon-
in large part by their lifetimes.
Of fundamental
band strengths,
region,
fluxes at the top of the atmosphere
perturbations
from halogenated
compounds
and at the surface, -- namely the addi-
385
PRECEDING
PAGE
B' _'_'" "-',,,a
NOT
F:LMED
GLOBALWARMING tional heating to increase
induced
in the tropical
temperatures
considerable
significance
Candidate
alternatives
HFCs) or carbon,
upper troposphere
in this region.
Any change
and lower
for the tropospheric-stratospheric are composed
hydrogen,
and fluorine
hydrogen
which has the potential
near the tropopause
exchange
of either carbon,
chlorine
stratosphere
in the temperatures
water
region
is of
(hydrofluorocarbons
or
vapor.
and fluorine
(hydrochlorofluorocarbons
or HCFCs).
For simplici-
ty, both classes of compounds are referred to as hydrohalocarbons. Because they contain hydrogen, the hydrohalocarbons are subject to destruction in the atmosphere through reaction with hydroxyl radicals. This destruction
mechanism
pounds (see [Fisher of these gases). upper
factor
et al. (1989a)]
By contrast,
stratosphere.
a primary
leads to much shorter for a discussion
This paper examines
below,
their potential
the calculated
lifetimes
of the chemistry
the only known destruction
As will be shown in reducing
atmospheric process
the shorter
for the hydrohalocarbon
affecting
the atmospheric
of CFCs is through
atmospheric
lifetime
comlifetimes
photolysis
of HCFCs
in the
and HFCs is
to affect global warming.
greenhouse
effects of several one and two carbon halocarbons.
Esti-
mates of these effects will be quantified in terms of a relative potential to enhance global warming (halocarbons global warming sient relative
potential or HGWP). warming
effects
Sensitivity
to assumed
will be analyzed.
Table
1 Compounds
HALOCARBON
FORMULA
IUPAC
CFC-|
|
levels of trace gases will be examined.
Examined
in this Study
NAME
CC13F
METHANE,
CFC-12 CFC- 113
CC12F2
CCI2FCCIF2
METHANE, DICHLORODIFLUOROETHANE, 1,1,2-TRICHLORO1,2,2-TRIFLUORO-
CFC- 114
CCC1F2CC1F2
ETHANE,
1,2-DICHLORO-
CFC-115
CCIF2CF3
ETHANE,
CHLOROPENTAFLUORO-
HCFC-22
CHCIF2
METHANE,
HCFC-123
CF3CHC12
HCFC- 124
CF3CHCIF
ETHANE, ETHANE,
HFC- 125 HFC- 134a
CF3CHF2 CF3CH2F
ETHANE,
2-CHLORO-1,1,1,2-TETRAFLUOROPENTAFLUORO-
ETHANE,
1,1,1,2-TETRAFLUORO-
HCFC- 14 lb
CC12FCH3
ETHANE,
HCFC- 142b
CCIFECH3
HFC- 143a
CF3CH3
ETHANE, ETHANE,
1,1-DICHLORO-I-FLUORO1-CHLORO- 1,1-DIFLUORO-
CHF2CH3
ETHANE,
CC14
METHANE,
CCI3CH3
ETHANE,
HFC- 152a
TRICHLOROFLUORO-
CHLORODIFLUORO2,2-DICHLORO-1,1,
1,1, I-TRIFLUORO1, I-DIFLUORO-
CARBONTETRACHLORIDE METHYL CHLOROFORM
386
1,1,2,2-TETRAFLUORO-
TETRACHLOROI,I,I-TRICHLORO-
I-TRIFLUORO-
Tran-
GLOBAL WARMING Halocarbon
Global Warming
Potential
is based on a concept
similar to Ozone Depletion
Potential
and
is used to describe the relative potential of each halocarbon as a greenhouse gas. No attempt is made to calculate HGWPs for non-halocarbon gases such as carbon dioxide and methane. Because of the current atmospheric
concentrations
and spectral
locations
of the infrared
absorption
bands of these other gases,
calculated global warming is not a linear function with increases in their atmospheric concentrations. In contrast, a calculated warming is linearly proportional to concentrations of halocarbons. Thus, Greenhouse
Warming
Potentials
Two atmospheric Pont Central Radiative
modeling
Research
Convective
groups,
(Du Pont),
and methane
Atmospheric
have calculated
considered
would not be meaningful.
and Environmental HGWP
values
in the literature
This paper will discuss the definition
of HGWP,
Research,
for sixteen
gases. These
as well as examine
groups
used et al.
ozone (Fisher,
formula
et al., 1989a).
the basis for selecting
of the differences
and Du
1985, Owens
1 along with their chemical
for effect on stratospheric
by the two models and an examination
Inc. (AER),
(Wang and Molnar
in this study are listed in Table
names and are the same as evaluated
The results calculated results
dioxide
models that are described
1985). The halocarbons and IUPAC
for carbon
its definition.
and uncertainties
in model
is also presented.
2. DEFINITION
BASIS
Halocarbon Global Warming Potential (HGWP) is defined in a manner parallel to the definition of Ozone Depletion Potential. It is defined as the ratio of calculated warming for each unit mass of a gas emitted into the atmosphere relative to the calculated warming for a mass unit of reference gas CFC- 11. This definition was chosen as a representative measure of the potential of a compound to effect global warming for several reasons: (1) It provides
a measure
for each unit released
of the cumulative
into the atmosphere
effect on the radiastive
(3) It provides
a measure
effect of CFC-11
The first of these reasons
of the maximum
over its chemical
lifetime
(see below).
(2) The HGWP yields a single value for each compound
calculated
balance
calculated
rather than a time varying
multitude
effect of a compound
compared
in that it estimates
the cumulative
of values.
to the maximum
on an equal mass basis.
is perhaps
the most important
chronic effect
on global warming of each unit released. An illustrative test was performed which quantified the chronic effect from a single pulsed release of test gas into the atmosphere, analogous to a test on effect on stratospheric ozone (Fisher
et al.,
1989a). The test used the Du Pont model to calculate
over a 500 year time period
following
impulse
releases 387
of HCFCs
cumulative
global warmings
-123, -22, and CFC-11.
GLOBALWARMING 0.022
I
0.020
d
I
t
t
t
r
J
t
I
I_,
SPECIES
AREA (deg.*yr)
RATIO to CFC-11
HGWP
CFC-11 HCFC-22 HCFC-123
1.176 0.358 0.019
1.0 0.30 0.016
1.0 0.29 0.015
0.018 0.016 0.014
dts 0.012
(deg.
T I
K)
0.010
I
0.008
i
0.006
-
0.004
-
0.002
-
I
"\"
0.000
_'
0
I
I
20
40
I
60
i
" -7 ........
",
80
100
t
t
120
140
I
i
160
i
180
200
Year
Figure 1. Calculated Change in Surface Temperature kg of Specified Gas
The calculated following atmospheric
cumulative
warmings
are shown in Figure
the release and tails off with an exponential lifetime
of the species.
such an event echo the relative
a Pulsed Emission
having a time constant
As seen in the insert table, the time-integrated calculated
this is not surprising
of 5.0x10"
*9
1. For each case, the effect peaks very rapidly
decay function
values of the HGWP
Appendix A of Fisher et al. (1989a), greenhouse warming.
Following
warming
from steady state figures.
if the response
function,
equal to the following
Referring
to
g(t), is to represent
3. DEFINITIONS
In order to make the definition of HGWP consistent between of relative effects, the following criteria have been selected: 1) Trace gas levels -- Changing
the concentration
models as well as a conservative
of other trace gases will affect the calculated
estimate
future
equilibrium temperature rise from gases under evaluation here for two reasons. First if there is overlap of absorption spectra, certain bands have less effect. Secondly, chemistry and therefore lifetime can be 388
GLOBALWARMING affected by perturbation of these chemicals. Current levels of CO2, CH4, N20, 03 and stratospheric H:O were used in model calculations. Sensitivity of this assumption will be tested in a following section. 2) Gas perturbation responses
levels -- Atmospheric
large enough to avoid the "noise
concentrations levels"
of the test gases were chosen
of the numerical
to yield model
models and still be in a linear response
region. 3) Reference gas -- CFC-11 has been chosen as the reference compound er to have a reference material consistent for both HGWP and ODP. 4) Specific
Surface Temperature
Change
-- We define the calculated
for HGWP calculations
surface
a one part per billion surface increase of any gas to be specific surface temperature
in ord-
temperature
increase
for
change,
or symbolical-
ly dT s. The HGWP
definition
resembles
Calculated
IR forcing
Calculated Emission IR forcing
Since radiative
IR forcing
is the net change
convective
to (moleculear
[dTs(CFC
can chemically
influence
a surface
change
approximately
below) and since lifetimes are proportional
* emission
rate), an equivalent
proportional
to the ratio of atmospheric
form of this definition
is:
11)/Molecular
the distribution
of affecting
weight(CFC heating
11)]
rates indirectly
as well since they
of ozone which would affect both the solar and the long wave
of model results indicates
that this is a second
order
effect,
of these calculations
at least two (Wang et al.
1989).
CALCULATIONS
appropriate
input to these radiative chemistry
Once the concentration vective
temperature
below the IR effect and well below the sensitivity
communication,
The primary using
X
in IR flux at the tropopause.
11) * Lifetime(CFC
rates. An examination
orders of magnitude
4. MODEL
X/
state) of CFC-11
Note also, many of the gases have the potential
private
is:
due to CFC-11/
models calculate weight
definition
[dTs(x) * Lifetime(x)/Molecular weight(x)] ............................................................................
HGWP
heating
Thus for any gas, the general
due to Compound
rate (steady
to the IR forcing level (to be examined abundance
definition.
Emission rate (steady state) of Compound ........................................................
HGWP
Note:
the ODP
model.
calculations
are the altitudinal
steady-state
concentration
profiles
models.
profile is determined,
These models utilize infrared
the effect of each gas is calculated absorption 389
spectra to quantify
using a Radiative
Con-
a gas's ability to absorb
IR
GLOBAL WARMING
Table 2 Total Rogers
Varanasi
Gehring
Chudamani (1988)
et al. (1983)
(1987)
CFC-11
2389
2566
CFC-12 CFC-113
3364
4822
3267 3507
CFC-114
5935
3937
Stephens (1988)
&
of Halocarbons
Kagann
Species
&
Band Strengths
Magid + (1988)
2389* 3310 3126
3240* 3401" 4141"
CFC-115
4678*
HCFC-22
2399
2554*
HCFC- 123
2552
2859*
HCFC- 124
4043*
HFC- 125 HFC- 134a
3908* 3169
3272*
HCFC-141b
1732
1912"
HCFC- 142b
2474 3401"
2577*
HFC- 143a HFC- 152a
1648" 1195"
CC14 CH3CC13
1184
1209"
* Infrared data used in model calculations + The IR data from Magid tegrated
energy
band strengths
and thereby accounts
were given with spectral
impact the earth's
that the solar heating culation
(1988)
resolutions
are given here so that they can be compared
is balanced
heat balance.
by the infrared
for the amount
of energy
Equilibrium
temperature
cooling at all altitudes
absorbed
of 0.5 to 0.25 cm -1. The in-
to other data.
profiles are calculated
through
the atmosphere.
by each IR gas (the band strength)
such
The cal-
at specified
wavelengths (the band location) including spectral overlap with other IR gases. Quantitative infrared data for this input are available from literature sources for the CFCs (Kagann et al. 1983; Varanasi and Chudamani, 1988; and Rogers and Stephens, from industry
laboratories
Total band strengths the exception
(Magid
available
1988) and measurements 1988, and Gehring for these calculations
and the HFCs were obtained
as shown
in Table 2 are within about
of Rogers and Stephens (1988). The band strengths used for the model calculations
with an asterisk.
Since there appear to be systematic
measurements,
the values from a common
the compounds
of interest in this study. For compounds
(1987)
for the HCFCs 1987).
differences
between
data base [Magid (1988)]
was used. 390
not available
laboratories
10% with are marked
for band strength
were used since it covered from this source,
most of
data from Gehring
GLOBALWARMING
0
_J
6
6 >.,
U3 (-
°J
6
U3
03 "O
A
Cs_ e
d
_E O
co
,m
3.0
2.5
CFC-12
2.0
1.5
1.0
0.5
0.0
....
0
F ......
50
t ....
100
P ....
150
-_- .....
200 Time
Figure 4. CalcuLated (CFC-11 Reference)
Relative Warming Following [Du Pont 1-D Model]
399
I.....
250
I......
300
_....
350
ff .....
400
450
(Yrs)
a Step
Change
of Emission
of Specified
Gas
GLOBAL WARMING
(Du Pont 0.12
1-D Model)
t
I
t
I
I
I
•/J
0.11 4.p , ,.z• " ""
0.10 J
/.
f
*
f
0.09
/"
p p
•/ /"
,/ /
/'"
/
0.08
//
/, j J /
I ./t
/ /
// //
_f'
0.07
//
/. i""
dTg 0.06 (deg K) /p#'
0.05
p j p
,"
/" ,/"
//
0.04f
i"
.....
0.03 0.02 0.01 0.00 -10
I
I
I
I
I
I
I
I
I
I
0
10
20
30
40
50
60
70
80
90
100
Time
(Yrs)
with
various
CFC-11 CFC-12 ...................HCFC-22 ..... HCFC-123 .......... HCFC-141b .............. CFCl15 No Replacement
Figure 5. Transient Calculated species at t = 0 and constant
Global Warming; emission.
400
Ib/for/Ib
replacement
of CFC-11
GLOBAL WARMING the relative amount in the atmosphere, the relative effects either grow or decrease depending on whether the lifetimes are longer or shorter than that of CFC-11. As seen in Figure 4, the HCFCs have lifetimes shorter
than the lifetime
of the reference
HGWP
value with a time constant
gas and have relative
equal to the lifetime
effects that grow with time asymtotically OWN lifetime. Another perspective transitions
approaching
warming.
Longer
their HGWP
ing from substitution
for CFC-11
lived species
of compounds
were meant to estimate
were used,
are substituted
of THEIR
and the resulting
the warming
scenarios changes
per-
result-
level and growth (in atmospheric
namely 260 pptv and 4.0%/yr.
on an equal mass basis. Results
the
have relative
value with time constant
of various gases for CFC-11 at time, t = 0. Current
Compounds
approach
Figure 5 shows the results of a simple set of substitution
formed using the Du Pont model. These calculations
constant.
of CFC-11.
on the transient response is to consider the replacement
in calculated
concentrations)
effects that asymptotically
Emission
levels were assumed
for all HCFCs
fall within the enve-
lope bounded by the no replacement results and the results for continued emission of CFC-11 and show a negative trend in warming within a few years of substitution. Results for CFC-12 and CFC-115 on the other hand show continued
positive
slope exceeding
the CFC-11
no-substitution
case for all times.
UNCERTAINTIES Uncertainties
in the the effectiveness
-- those that are generalized species There
considered
radiative properties temperature
to the total greenhouse
of problems
that need to be resolved
need to be quantified
structure of the atmosphere of oceans
which
Uncertainties balance. profiles
also exist regarding
Research
of questions
ing and magnitude
of continuing
HCFCs,
of surface
warming.
patterns and chemistry to surface
warming.
balance
of individual affecting
species
The
and changes
Changes
in the
of the stratosphere.
temperature
changes
will also
to understand
these
of the earth.
and HFCs and their influence
The chemical processes
on the radiative
need to be resolved
both lifetimes
and
and atmospheric
research.
related to the general greenhouse
of global warming,
of greenhouse
is being carried out worldwide
of the absorptances
for use in climate models.
for halocarbons
and ocean currents
the CFCs,
dependence
are also the subject
Resolution
classes
to the individual
in the surface and ice cover albedos, as a function
apply to ALL trace gases that affect the future radiative
The temperature
parameterized
fall into two general
that are specific
in the modeling
will affect the convective
(as heat reservoirs)
affect the timing and location of the warming. questions
effect and those
of the earth's surface such as changes
and composition
The coupling
global warming
here.
are a number
in cloud cover
of gases to produce
whereas resolution
will have a direct effect on the HGWP
warming
will directly affect the modeled
of the radiative
and chemical
tim-
parameterizations
values for these species.
7. ACKNOWLEDGMENTS The authors are grateful for the support received bon Environmental
Acceptability
for this work from AFEAS,
Study).
401
(Alternative
Fluorocar-
Xo
IMPACT ON PHOTOCHEMICAL INCLUDING TROPOSPHERIC
An Assessment
of Potential
lmpact
of Alternative Hiromi
Fhu_rocarbons
OXIDANTS OZONE
on Tropospheric
Ozone
Niki
Centre for Atmospheric Chemistry Department of Chemistry York University 4700 Keele Street, North York Ontario, Canada M3J 1P3
PRECEDING
PAGE B;..;:.;,_K Nor
FILMED
TROPOSPHERIC OZONE EXECUTIVE One type of tropospheric tion as precursors assessment 1.
the following
specific
On a global
halocarbons
may arise from their possible
of 03 and other oxidants on urban issues related
Is it likely that the HFCs and HCFCs in the vicinity
2.
impact of the alternative
to the formation
SUMMARY
to tropospheric
would contribute
and global scales.
contribu-
In the present
oxidants are addressed: to production
of photochemical
oxidants
of release? basis, how would emissions
of HCFCs
and HFCs
compare
to natural
sources
of 03
precursors? Since almost all CFCs are emitted in urban environments,
the first question
deals primarily
with urban
"smog" formation, Salient features of chemical relationships between oxidants and their precursors as well as the relevant terminologies are described briefly in order to provide a framework for the discussion of these two issues. Based on an analysis of the atmospheric reactivity
and 03 forming
to 03 production
potential,
concentrations
the maximum
in both urban and global atmospheres
1: Urban Atmosphere
(values in parenthesis
HFCs:
CH3CHF2-152a
HCFCs:
CHC1F2-22
2: Global Atmosphere
(59), CH2FCF3-134a
HFCs:
CH3CHF2-152a
HCFCs:
CHC1F2-22
CH3CCI2F-141b
(8), CHF2CF3-125
fluorocarbons
as follows: of all 03 precursors):
(4) (16),
(59)
in units of 10 -3% of the total contribution
(92), CH2FCF3-134a
(11), CH3CC1F2-142b
and their atmospheric
of the alternative
have been derived
(6), CH3CHC1F-124
(13), CHCICF3-123
(values in parenthesis
03 precursors,
contributions
in units of 10-3% of the total contribution
(8), CH3CC1F2-142b
CH3CC12F-141b
of various
projected
(11), CHF2CF3-125 (10), CH3CHCIF-124
(20), CHCICF3-123
of all 03 precursors):
(7) (25),
(92)
405
PRE'C.EOING
P.-,,_,.Jr_.'_'C
B_.,'_'..._K :_' NOT
F;_L_'FZ)
N92-15448
ASSESSMENT
OF POTENTIAL
IMPACT OF ALTERNATIVE TROPOSPHERIC OZONE
FLUOROCARBONS
ON
Hiromi Niki
Centre for Atmospheric
Chemistry
Department of Chemistry York University 4700 Keele St., North York Ontario,
Canada
M3J
1P3
PRECEDING
P',_GE Bi._':.i,_K NOT
F_.ML_
TROPOSPHERIC OZONE 1. INTRODUCTION While
the chlorofluorocarbons
inert in the troposphere,
(CFCs)
such as CFC-11
the hydrogen-containing
to a large extent, be removed
halocarbons
in the troposphere
and CFC-12
(CFCI3)
being considered
by the HO radical.
(CF2CI2)
chemically
are
as their replacements
These alternative
halocarbons
can, include
the hydrochlorofluorocarbons (HCFCs) 123 (CF3CHCI2), (CHF2CI) and 124 (CFaCHFC1) and the hydrofluorocarbons
141b (CFCI2CH3), 142b (CF2C1CH3), 22 (HCFs) 134a (CF3CHEF), 152a (CHFECH3)
and 125 (CF3CHF2).
(k) for the HO radical reaction
pounds
[Hampson,
Listed in Table 1 are the rate constants Kurylo and Sander,
1989] and their estimated
chemical
lifetimes
of these com-
in the troposphere
[Prather, 1989; Derwent and Volz-Thomas, 1989]. In this table, values of the lifetimes of these selected HCFCs and HCFs are seen to vary by more than a factor of more than ten ranging from 1.6 years for HFC
152a and HCFC
or minimizing alternates.
125 to as long as 28 years for HFC 125. Clearly,
impact on stratospheric
However,
be assessed
and taken into account
One type of tropospheric tion as precursors assessment 1.
specific
with short tropospheric
consequences
in the selection
impact of the alternative
to the formation
the following
of their degradation
of avoiding
lifetimes are the desirable in the troposphere
should
process. halocarbons
of 03 and other oxidants issues related
Is it likely that the HFCs and HCFCs the vicinity
2.
03, those halocarbons
potential environmental
from the standpoint
on urban and global
to tropospheric
would contribute
may arise from their possible oxidants
to production
scales.
contribu-
In the present
will addressed: of photochemical
oxidants
in
of release?
On a global basis,
how would emissions
of HCFCs
and HFCs
compare
to natural
sources
of Oa
precursors? Since almost all CFCs are emitted in urban environments, "smog" formation. and their precursors a framework
the first question deals primarily
In the following section, salient features of chemical as well as the relevant terminologies will be described
for the subsequent
report deals only with possible
discussion
of these two issues.
direct chemical
with urban
relationships between oxidants briefly first in order to provide
It should be mentioned
that the present
effects and not with indirect climate-chemical
interactions
[cf. Wang 1986; Ramanathan et al. 1987; Wuebbles et al. 1989]. Namely, the alternative halocarbons and/or their degradation products may act as "green-house" gases and alter the global tropospheric 03 distribution cussed
via changes
elsewhere
in climate and emission
in the AFEAS
rates of natural
precursors
of 03. The latter topic is dis-
report.
2. BACKGROUND 2.1. Photochemical
Oxidants
The present assessment deals specifically with issues concerning 03 rather than "oxidants" The term "oxidant" is often used loosely and deserves clarification. Very often, it refers
in general. implicitly to
03, the most abundant oxidant in the troposphere. However, there are many other trace atmospheric gases which are also known as "oxidants," e.g. hydrogen peroxide (H202), peroxyacetyl nitrate (PAN), and formic acid (HCOOH).
As already discussed
elsewhere
in the AFEAS
report [cf. "Degradation
Products
409
PRSCEDING
P._,GE 13t ,_.,_:, ,.r.,v NOT
F!LMED
TROPOSPHERIC
OZONE
Table
1 Rate
Constants
for
the
HO Reaction
of
Alternative
A-Factor Compound
Fluorocarbons
k(298
x 10 -lz
E/R
K) (a)
x 10 "Is
Lifetime
(d)
(yr)
HFCs (b) CH3CHF2
152a
1.20
1100 + 200
37.0
1.7
CH2FCF3
134a
1.70
1750_+300
4.8
13.2
CHF2CF3
125
0.38
1500 _+500
2.5
25.4
22
1.20
1650 _+ 150
4.7
3.5
CH3CC1F3
142b
0.96
1600_+
150
3.8
16.7
CH3CHCIF
124
0.66
1205 _+300
10.0
6.3
CH3CCI2F
141b
0.27
1050 _+300
8.0
7.9
CHC12CF3
123
0.64
850 _+ 150
34.0
1.7
0.15
0 _+300
150.0
CH4
(1 +0.6 Patm) 2.30
1700 _+200
C2H6
11.00
1100 + 200
CH3CCI3
5.00
1800 _+200
HCFCs
(b)
CHCIFz
(a) k in cm 3 molecule from
Hampson,
(c) Taken
from
NASA
(d) Lifetime
=
1981)
et al.,
Patm) 7.7
280.0 12.0
8.2 0.2 5.3
-_ s -_
(b) Taken
Volz
(1 +0.6
0.3
1/k[HO];
Kurylo
Kinetic
Data
and
Sander
(AFEAS
Report,
1989)
(1987)
k at 298 K; [HO]
taken
to be 5xlO 5 molecule
410
cm -3 (Crutzen
and Gidel,
1983;
TROPOSPHERIC OZONE of Alternative of a variety oxidants
Fluorocarbons of products
derived
in the Troposphere"],
which can be considered
from the alternative
and their potential
tropospheric
the alternative as "oxidants."
halocarbons
halocarbons
can lead to the formation
Some of the halogen/carbon-containing
may play important
roles in atmospheric
environments
impact must be assessed.
Broadly speaking, the term "oxidant" simply refers to the oxidizing ability of a reagent, i.e. to remove electrons from, or to share electrons with, other molecules or ions [Finlayson-Pitts and Pitts, 1986]. The ability of a chemical and is expressed
species
to oxidize or reduce
in volts. For example,
other chemical
03 has a standard
species
potential
is termed
its "redox
potential"
of + 2.07 volts in the redox pair of
O3/H20, and hydrogen peroxide + 1.776 volts in the redox pair, H202/H20 [Weast, 1977]. Historically, the term "oxidant" has been defined by a wet chemical technique; that is, an oxidant is any species giving a positive
response
ion in solution
in the KI method.
to form brown
The basis of this method
2H + This technique of measuring In addition, the U.S. Federal oxidant
is the oxidation
of the colorless
iodide
12: + 2I- + 03 --' I2 + 02
+ H20
and reporting total oxidants was used almost exclusively until the mid- 1970s. Air Quality Standard was written in terms of "total oxidant" (0.08 ppm
for 1 h) rather than 03 specifically.
A variety
of air pollutants
give a positive
response,
but some
interfere negatively. Namely, "total oxidants" will include a weighted combination of various pollutants such as 03, NO2, and PAN, but SO2 gives a 100% negative response and must therefore be removed with the use of a scrubber, The recognition
e.g.
of the problems
of physical
techniques
Air Quality
Standard
from the gas stream
Cr203,
with the wet chemical
for monitoring from oxidant
the major oxidant the UV method
air, and is accepted
method"
as an "equivalent
the term "photochemical ticular context. 2.2 Ozone
below.
and the simultaneous
03 specifically, the standard
led to a change was relaxed
is most commonly
in a species-specific
in the Federal
to higher
used to monitor
by the EPA [Finlayson-Pitts
must be defined
development concentra-
03 in ambient
and Pitts 1986]. In any case,
manner
depending
upon the par-
Precursors
Within the context monoxide
oxidant"
to analysis.
KI technique
to O3; simultaneously
tions, 0.12 ppm 03 for 1 hr. Today,
prior
of the present
and various
Namely,
assessment,
volatile organic
the term "ozone
compounds,
it is now well-established
particularly
that significant
precursor"
can be equated
hydrocarbons,
in-situ photochemical
with carbon
for reasons
stated briefly
production
and destruc-
tion of 03 takes place on urban, regional and global scales [WMO 1985; Logan 1985; Finlayson-Pitts and Pitts 1986; Crutzen 1988]. Tropospheric 03 production occurs via carbon monoxide and hydrocarbon oxidation,
with NO x ( = NO + NO2) acting as a catalyst.
species participate ed as:
interactively
in these chemical processes.
HC + NO x + hv _ where
HC denotes
various
reactive
03
carbon-containing 411
of molecular
and free radical
The overall reaction mechanism
A large number
can be represent-
+ other products compounds,
particularly
(1) hydrocarbons,
and hv is
TROPOSPHERIC OZONE solar radiation production lowed
reaching
the earth's
of 03 is due entirely
by the recombination
surface
in the wavelength
to the photodissociation
nm) --* NO
O + 02 + M --*03 M is any third body,
03. Thus,
strictly speaking,
O atoms are the primary in reaction NO
Reactions
2-4 alone do not provide
formation
and destruction
+
3
the energy
precursor
of the reaction
and stabilizes
of 03. NO2 can act as both the source
03 and regenerates
NO2:
NO2 + 02
_
of 03, thus establishing
(3)
(4)
of 03 but are largely
responsible
a steady 03 concentration
for controlling
governed
the
by the so-called
state relation,
where k is the rate constant
attributed
0
(2)
+ M
2 removes
a net production
[03]
According
+ O
such as 02 and N2, that removes
and sink for 03, since NO produced
photostationary
into NO and O fol-
of O with 02: NO2 + hv(_ Urn. 439
than
sea-salt
and
aerosols. Comment
the
of Kritz
of considerably
in the flux of sea-salt
Ma-
Wilkniss and Bressan (1972) Wilkniss and Bressan (1972) Chesselet et al. (1972) Peirson et al. (1974) Wada and Kakabu (1973) Buat-Menard et al. (1974) Martens eta]. (1973) Kritz and Rancher (1980) Parungo et al. (1986) Vong et al. (1988)
those
NATURAL SOURCES Robbins
et al. (1959)
suggested
that aerosol
NaC1 + 2NO2 Thus nitrosyl chloride
(NOCI)
chloride
could react according
--* NaNO3
+ NOCI.
(R1)
would be the form in which the chlorine
bins et al (1969) noted that NOCI would rapidly hydrolyze
to
is released
in the atmosphere
from aerosol.
to form HCI. This mechan-
ism is deemed unlikely now (cf. NRC, 1975). Eriksson (1959), and Duce et al. (1973) assumed gaseous inorganic chlorine is most likely to be HCI which is released via H2SO
Hitchcock
4 +
2NaCI --* (sea-salt)
et al. (1980) found high correlations
Na2SO4
between
(R2)
Cl-depletion
in filter samples of aerosols collected on the coast of North Carolina confirmation of Eriksson's hypothesis of R2. Clegg and Brimblecombe
(1986) have shown that Henry's
that the
2 HC1.
+
Rob-
and excess (non-sea
and interpreted
law considerations
salt) SO42-
their findings as strong
involving
equilibrium
be-
tween gaseous HC1 and the aqueous ions indicate that reaction R2 or any similar reaction involving a mineral acid that is less volatile than HC1 goes essentially to completion for relative humidities below 98 %. In respect to the atmosphere, this means that HNO3 can release HC1 as well as H2SO 4. Thus to explain the release of gaseous HC1 to the atmosphere when the primary sea salt particles dehydrate, R2 can be rewritten as H ÷ + NaC1 _ (sea-salt)
Na ÷ + HCI.
(R3)
In this equation, it must be understood that the hydrogen ion is supplied by acids of lower volatility than HC1 and that for the atmosphere H2SO4 and HNO3 are the most abundant species available for the task. Given the observations that the degree of chlorine depletion of sea salt aerosols is generally less than 20%, it is clear that the gaseous and aerosol forms of HCI are not in equilibrium, even over the oceans. The mechanism
represented
by R3 has received
considerable
support
from the recent work of Legrand
and Delmas (1988) who examined the results of several ice core (Delmas et al. 1982, Legrand and Delmas, 1984, 1985) and air sampling programs (Duce et al., 1973 and Maenhaut et al., 1979) in Antarctica concerning
chlorine.
They used ion balances and calculated acidity for two circumstances
1. When C1- is in excess of Na + relative
to bulk sea water:
[H ÷] = IxsSO4 =] 2. When CI- is depleted
relative
as indicated below.
+ [NO3-]
+ [xsCl-].
to Na ÷ :
[H ÷] = [xsSO4 = ]a + [NO3-], where [xsSO4 = ]a is the portion of excess not been neutralized by the above reaction. This system thus assumes
that when C1- is in excess the reaction
extent, whereas when CI- is depleted the reaction has proceeded 440
has not proceeded
toward completion
sulfate that has
to an important
leaving some unneutral-
NATURAL SOURCES ized xsSO4 = behind to contribute equivalent sulfate
concentrations,
its acidity (thus the subscript
is that which cannot be ascribed
from sea-salt.
The original
sea-salt
to sea-salt
contents
sea water. The excess sulfate is considered SO4 =. The difference
a). All quantities
which is the reason there is no factor of 2 preceding
between
based on the assumption
are assumed
in brackets
that all of the sodium comes
to have the same relative
to be the result of the conversion
are chemical
the sulfate terms. Excess composition
of gaseous
the total excess sulfate and xsSO4 = a represents
as bulk
SO2 to particulate
the amount
by which the
C1- is depleted. Legrand
and Delmas
(1988) used the above model and the observed
NO3- and C1- in the ice cores to calculate
concentrations
the acidity which they then compared
of Na + , SO4 =,
to the observed
H +. The
agreement was very good for the two-hundred year period (a 16m long ice core) studied in detail. All of the major features and most of the minor variations were very closely in agreement. The model was able to account for the acidity during prolonged to Na +. The authors from sea-salt suggest
could
not state with certainty
since volcanoes
that the aerosol
periods when CI" was both in excess and in deficit relative
and other sources,
that the HC1 (i.e.,
including
source is the most likely one to account
sion and permits
a useful
From a global perspective, and nitrogen excess sulfate
of reactive
of reaction
is from pollution
chlorine
sources,
R3 represents
data. A glance at Table
Legrand's
an important
to be much
and Delmas'
link between
cycle on the other because,
in the troposphere.
the amounts
they
conclu-
cycle.
cycles on the one hand and the chlorine
it may be the main source by human
the operation
entirely
However,
from sea salt is estimated
This then supports
view of the global chlorine
are known.
for the Antarctic
1 shows that even at the lower limit, the flux of gaseous C1 derived larger than the sum of all of the known other sources.
the xsCl-) was derived
human activities,
as shown in Table
Over continents
of HCI released
the sulfur
where
must be considered
1,
much of the to be affected
activities.
e. The organic
chlorine
The most abundant
source
natural
chlorine
which has its origin in the oceans.
containing
is the source of CH3I. of biological processes forward to estimate and tropospheric
its iodine atom for a chlorine
that of the surface
water and in the air over the oceans.
oceans.
Lovelock
its flux into the atmosphere
Zafiriou
atom in the laboratory that biomethylation
CH3C1 (1975)
at tempera-
CH3I also has been found in low concentrations et al. (1973) suggested
based on measured lifetime.
Other organic
(cf Burreson et al., 1975) but their concentrations
as sources of atmospheric of active chlorine concentrations.
is methyl chloride,
in ocean
of I in the oceans
So it is possible through the exchange reaction that CH3CI is a secondary product in the oceans. Despite the uncertainty of the origin of CH3C1 it is relatively straight-
air and on its tropospheric
in marine organisms
in the atmosphere
The details of its source in the oceans are not known.
has shown that CH3I readily exchanges tures approximating
molecule
chlorine.
in the stratosphere
Finally it is noteworthy
concentrations chlorine
have been found
are so small as to be entirely negligible
that CH3C1 represents
which in turn represents
in surface ocean waters
molecules
a natural
regulator
the major natural
source
of stratospheric
ozone
f. The cycle and its balance From the above discussion of atmospheric
chlorine
of chlorine
sources
it is clear that the oceans are the overwhelming
and that the bulk of atmospheric 441
chlorine
source
exists over the oceans in the forms of
NATURAL SOURCES aerosol
derived
from sea salt and gas, probably
both forms of chlorine rine is deposited over the oceans.
by transport
HC1, released
from the marine
from the aerosol.
atmosphere.
The continents
receive
About 90% of the sea-salt derived
chlo-
back into the oceans. Thus it is seen that most of the atmospheric chlorine cycle operates The 10 % of chlorine transported to the continents is deposited on the surface from which
it finds its way to rivers and streams and back to the oceans. Recent studies indicate that there may be significant aerosol chlorine contributions by forested areas. The possible release of gaseous chlorine from the plant derived dustrial
regions,
presumed
aerosol
has not been investigated.
to be of anthropogenic
The amounts
Chlorine
in excess of that which can be ascribed
of chlorine
in Table 1 represent
found in continental
to sea salt (relative
air, particularly
in in-
to sodium) has generally
been
origin.
injected
into the atmosphere
a forced balance.
The magnitude
in sea salt and the amounts
of the uncertainty
deposited
as given
of sea salt source strength
makes
it is possible that a secondary source, such as forests might make a significant contribution to natural chlorine in continental air. This is a subject for further investigation. We can judge the consistency of the cycle by using the estimates of Cl-deposition tion over continents to estimate the average served concentrations.
Table 3 provides
in precipitation on continents and the known total precipitaC1 concentrations in precipitation and compare them to ob-
the necessary
information.
The precipitation
Werby (1958) for the United States (mid 1955 - mid 1966) were selected because in extent and are less affected by pollution than subsequent surveys. The relatively tween the calculated
and observed quantities
listed in Table 3b reflect consistency
of the cycle. That is to say that there appear
to be no unknown
significantly
by the rather
alter the balance
as represented
sources
generous
data of Junge
in the quantitative
or sinks of chlorine
ranges in Table
the ranges of uncertainty
components
global average
cycle. Obviously
lacking are reliable
aspects
that could
1. However,
clear that there is much more insight to be gained by narrowing of the chlorine
and
they are continental close agreement be-
it is
in the various
values of concentrations
in air and precipitation.
Table 3a. Fluxes
of water
and chlorine
Precipitation over continents CI deposition
Table 3b. CI concentration
(Tg yr "_)
9 x 107 520 - 1500
(ppm) Calculated
from above
Observed
6 - 17
Precipitation
0.1
-
8a
Reference: a. Junge and Werby (1958)
The Fluorine Cycle Most of the fluorine and 0.09%
in the earth's
crust is in solid mineral
by weight of the upper layers of the lithosphere
borne soil dust can and does contribute The abundance
of fluorine
ships among the dissolved
to the atmospheric
form where (National
burden
it constitutes
Research
Council,
between
0.06%
1971). Wind-
of fluorine in the form of soil minerals.
in the oceans is 1.3 ppm by weight and is controlled
by equilibrium
relation-
species F-, MgF +, CaF +, and NaF and the solids MgF2 and CaF_. The mass 442
NATURAL SOURCES ratio of F/C1 in seawater as it is for chlorine. mosphere
is 6.7 X 10-5. The marine
The question
aerosol
arises as to what extent,
is therefore
a source of atmospheric
if any, gaseous
fluorine
fluorine
is released
to the at-
from the sea salt aerosol.
Cicerone
(1981) noted in his review that there is virtually no quantitative
in the atmosphere. concerned
Barnard
with fluoride
and Nordstrom
in precipitation.
(1982) have reviewed
information
about natural fluorine
most of the prior work, which is mainly
The work of Symonds,
Rose and Reed (1988) provides
a new
perspective for the role of volcanoes, albeit the flux estimates range over an order of magnitude. In contrast to the case of chlorine, volcanic activity could be the most important natural source of gaseous fluorine, most likely in the form of HF. Symonds, Rose and Reed (1988) give estimates of various emission rates for natural and anthropogenic sources of fluorine. These estimates along with information from Erickson and Duce's
(1988)
study of sea-salt
Table 4. Global Atmospheric
flux are incorporated
Fluxes
in Table 4.
of Fluorine
Natural F(sea-salt) HF(g)
to atmosphere:
0.4-
sea salt to atmosphere:
HF (g) volcanos
0-
to atmosphere:
1 Tgyr -_ 1 Tg yr "l
0.06 - 6 Tg yr -1
Soil dust to atmosphere:
400 mg/kg (> 2.9 mmol/kg)
(Rosenberg,
sodium
Several
LD50 values have been
trifluoroacetate
1971), > 2000 mg/kg (>
intraperitoneally,
14.7 mmol/kg)
(Airak-
sinen and Tammisto, 1968), > 5000 mg/kg (> 37 mmol/kg) (Blake et ai., 1969), and > 2000 mg/kg (> 14.7 mmol/kg) (Airaksinen et al., 1970) were obtained. TFA itself produced death in two of five mice treated intraperitoneally et al.,
at 150 mg/kg (1.1 mmol/kg),
1969). The LDs0 of sodium trifluoroacetate
probably
as a consequence
when administered
intravenously
of its acidity (Blake to mice was 1,200
mg/kg (10.5 mmol/kg) (Airaksinen and Tammisto, 1968). Preadministration of phenobarbital (40 mg/kg/day) for three days, or L-cysteine, isoniazid, ethanol, 4-iodopyrazole, or allopurinol administration 10 min before and 3 hr after sodium triftuoroacetate administration did not affect its LDs0, suggesting that the acetate was not being metabolized to toxic products (Airaksinen et al., 1970). Acute lethalities of the ord456
BIOLOGICAL ANDHEALTHEFFECTS er reported
for TFA, categorize
points, primarily
it as a "slightly
toxic" substance
(Klaasen
et al.,
1986). Other toxic end-
involving effects on metabolic activity, have also been investigated.
Sodium trifluoroacetate
in saline was administered by a single injection intraperitoneally to Swiss, albino, (Rosenberg, 1971). By 12-hr after administration of 2000 mg/kg (14.7 mmol/kg) the coenzyme
NADPH
in the liver was statistically
significantly
decreased
The decreased levels returned to normal by 24-hr after administration levels in the livers were also statistically after administration
significantly
and by 24-hr these levels
decreased
male mice (17-20 g) the concentration of
from 0.44
(Rosenberg,
to 0.25 /_mol/g.
1971). Reduced glutathione
from 4.33 to 3.94/_mol/100
had also returned
to normal
(Rosenberg,
mg at 12-hr 1971).
Male Wistar rats (200-260 g) were administered TFA in the drinking water for 5-6 days, equivalent to a dose of 150 mg TFA/kg body weight/day (1.3 mmol TFA/kg body weight/day) (Stier et al., 1972). In TFA-treated content
rat liver relative
decreased
by 24%,
to untreated
the neutral
rat liver, the soluble protein
fat increased
by 43 %. None of these effects were evaluated in liver of TFA-treated
animals
was altered
increased
by 6%, the glycogen
by 10% and the percent liver weight to body weight
for statistical relative
significance.
to control
A number of enzyme
rat livers:
pyruvate
kinase
activities
decreased
by
42 %, phosphoglycerate kinase decreased by 10 %, glycerol l-phosphate oxidase increased by 125 %, glycerolphosphate dehydrogenase decreased by 4%, malic enzyme increased by 4%, glucose 6-phosphate dehydrogenase decreased
decreased
by 17%, glyceraldehyde
by 7%, malate dehydrogenase
and NADPH-oxidase
increased
3-phosphate
decreased
dehydrogenase
by 10%, isocitrate
by 7%. Again differences
effects
studies TFA has been administered
which
were sought.
However,
to animals,
week-old
male Alpk/AP
(0.09 or 0.22 mmol/kg) changes
but without
producing
attempt
strain rats (Lloyd et al.,
were noted in the testes
relative
When TFA (240 mg/kg, or small intestinal
2.1 mmol/kg)
by 10%
significance
kinase and glycerol
the certain
specific a no ad-
in a single dose to ten-
1988; Lloyd et al., 1986). At doses of 10 or 25 mg/kg
to untreated
controls
(Lloyd
and 2,2,2-trifluoroethanol histologically-detectable
was administered
intravenously
1986).
to male Wistar
rats no bone
of TFA, 2,2,2-trifluoroethanol and 2,2,2-trifluoroacetaldehyde, at equimolar doses produced decreases in intestinal dry weight and leukocyte counts (Fraser and Kaminsky, 1988).
significant
(7.4 mmol/kg) Wahlstrom,
intraperitoneally
and killed 24 hr later, at 2000 mg/kg
2000 mg/kg (14.7
mmol/kg)
every
and Kaminsky,
1988; Lloyd et al.,
significantly reduced body weight testicular damage.
precursors
g) were injected
(Fraser
et al.,
and no histological
1988). The metabolic
Swiss male mice (17-20
toxicity was detected
decreased
made to determine orally
body weight gains and relative testis weight were not affected,
Equivalent doses of 2,2,2-trifluoroacetaldehyde gain and relative testis weight, and produced
marrow
of pyruvate
in water and administered
by 4%, enolase
for statistical
exception
there has been no systematic
verse effect level for TFA. TFA was neutralized
dehydrogenase
were not evaluated
and it is doubtful whether any of the activities, with the possible 1-phosphate oxidase, were significantly affected. In several
decreased
(14.7 mmol/kg)
strom,
1971). There were no TFA-induced
1971). However,
at 1000 mg/kg
and killed at 12 or 24 hr later, at
second day for 14 days and killed on the 14th day (Rosenberg histological
treated mice. At the lowest dose of sodium trifluoroacetate were noted including a cloudy swelling of the hepatocytes dose (2000 mg/kg) vacuolization
with sodium trifluoroacetate
of the hepatocytes
even after multiple
changes
of any of the
(1000 mg/kg) histological changes in the liver with a slight fat accumulation. At the higher
was detected
doses no hepatic 457
in hearts or kidneys
and
at all time periods (Rosenberg necrosis
was detected.
and Wahl-
BIOLOGICAL ANDHEALTHEFFECTS Mutagenicity TFA has been tested for mutagenicity of Salmonella
typhimurium,
was incubated indication
assay using two histidine-dependent
TA98 and TA 100 (Baden et al., 1976). TFA (150 mg/plate,
in an agar-overlay
of mutagenicity
in the Ames bacterial
assay at 37°C for 2 days without
was obtained
under conditions
TA98,
TA 100, and TA1535
at all concentrations
to note that while trichloroacetic
system.
No
of TFA was confirmed under similar was not mutagenic with Salmonella
used up to 35.7 mg/ml
in the presence or absence of polychlorinated biphenyl (Aroclor mitochondrial supernatants (Blake et al., 1981). The concentration mum non-toxic concentration for the bacteria. It is important
1.32 mmol/plate)
activating
where a positive control (N-methyl-N'-nitro-N-
nitrosoguanidine) was highly mutagenic. This lack of mutagenicity conditions (Waskell, 1978). In a third study sodium trifluoroacetate typhimurium
a microsomal
strains
(0.26 mmol/ml),
1254)-induced rat liver or testes post of TFA in these assays was the maxi-
acid has also been found to be nonmutagenic
in the
Ames assay (Rapson et al., 1980; Waskell, 1978), it is a hepatocarcinogen in mice (Herren-Freund, 1987). Trichloroacetic acid has been demonstrated to produce peroxisome proliferation in mice (DeAngelo et al.,
1986), which
1980), although on these reports insight
has been proposed
it is questionable the potential
into its potential
as one of the mechanisms
whether this mechanism
of hepatocarcinogenesis
applies in humans (Elcombe
of TFA to act as a peroxisome
proliferator
(Reddy
et al.,
et al., 1985). Based
should be investigated
to gain
as a hepatocarcinogen.
In Vitro Toxicology TFA at 4 mM (450 mg/l) reduced albumin to 56% and 85 % of controls,
the binding of the drugs warfarin and phenytoin to human serum respectively. TFA at 10 mM (1140 mg/1) correspondingly reduced
the binding to 44% and 77 % (Dale, 1986). The results suggest that TFA generally affects the conformation of the albumin. The potential of TFA to produce metabolic disturbances was tested in vitro in cultured Morris
rat hepatoma
7288C cells (Ishii and Corbascio,
1971). TFA (2.0 mM, 230 mg/l) did not
affect uridine or thymidine uptake, while at 10 mM (1140 mg/1) leucine and acetate uptake by the cells was not affected. Thus at these concentrations DNA, RNA, protein and lipid synthesis by the cells was not affected. When TFA was infused at 200 tamol/hr into 100 ml of perfusion liver the levels of lactate and pyruvate uptake and turnover inhibit
decreased
of lactate and pyruvate.
rather than accelerate
metabolic
medium
for an isolated
perfused
after 10 min (Stier et al., 1972). TFA produced
This result is unusual
in that fluorinated
compounds
rat
a higher usually
processes.
Antigenicity Aqueous solutions of chicken serum globin (10-15 mg/ml) and TFA (1.2 M) were mixed in a ratio of 1 to 1.5 at 4°C for 15 min. The mixture was dialyzed against water and lyophilized to produce a complex of TFA and chicken serum globin, which was used to immunize rabbits (Rosenberg and Wahlstrom, Undep these conditions TFA acted as a hapten and elicited antibodies. The clinical significance observation is unknown. 458
1973). of this
BIOLOGICAL ANDHEALTHEFFECTS
Analysis
Several
methods
is quantitated matographic
for the analysis
of TFA in biological
material.
In urine or serum TFA
by neutralizing with sodium hydroxide, esterifying with 2,2,2-trichloroethanol, and gas chroanalysis with a nickel-63 electron-capture detector (Witte et al., 1977). The detection limit
is 1 _g TFA/ml (Mario
are available
et al.,
body fluid. Another 1980). In serum
gas chromatography
method
uses isotachophoresis
TFA has been methylated
on Poropak
Q (Fraser
to quantitate
urinary
or blood TFA
and the head space vapor phase analyzed
and Kaminsky,
by
1987).
2. CONCLUSIONS Overall
there is sparse available
toxicologic
data on TFA. The acute lethality
of TFA in mice suggests
that it is only slightly toxic, and that its lethal effects at high doses are not dependent While a no adverse marrow
effect level has not been determined,
or small intestinal
effects,
25 mg TFA/kg
240 mg TFA/kg
produced
on its metabolism.
in rats produced
no body weight gains, relative
no bone
testis weight
gains, or testicular histologic changes in rats, and 2000 mg/kg every second day for 14 days in mice produced no hepatic
necrosis,
or heart and kidney
histological
changes.
TFA at 2000 mg/kg in mice significantly decreased hepatic but after 24-hr both levels returned to normal. Administration rats decreased
the hepatic
glycogen
content by 24 %, the percent
NADPH and reduced glutathione levels, of 150 mg TFA/kg/day for 5-6 days to liver/body
weight by 43 %, hepatic pyru-
vate kinase activity by 42 %, and increased hepatic glycerol 1-phosphate oxidase activity the lowest dose at which effects have been reported is 150 mg/day for 5-6 days. TFA is not mutagenic,
but no carcinogenicity
data is available.
However,
trichloroacetic
by 125 %. Thus
acid is hepatocar-
cinogenic in mice, although it is also not mutagenic in the Ames assay. While no chronic toxicity data on TFA is available it appears likely that on the basis of its resistance to metabolism, rapid clearance, lack of mutagenic potential, and low acute toxicity TFA is unlikely to exhibit significant chronic toxic effects. For a more complete assessment of TFA toxicity chronic studies are required, as well as acute studies in species other than the mouse. be investigated,
to gain insight
A German Senate Commission
The potential
for TFA to act as a peroxisome
into its hepatocarcinogenic for the Evaluation
of Health Hazards
mended that a blood TFA level of 2.5 _g/ml is risk-free assessment
has no experimental
or epidemiologic
basis.
459
proliferator
should
potential.
(Dallmeier
in the Work Environment and Henschler,
has recom-
1981). However,
the
N92-15451
ASSESSMENT OF DEGRADATION
OF EFFECTS
PRODUCTS
D.C. McCune
ON VEGETATION
FROM ALTERNATIVE
FLUOROCARBONS
and L.H. Weinstein
Boyce Thompson Institute for Plant Research Ithaca, New York
PRECEDING
PAGE
DL/_._'_K NOT
RLMED
BIOLOGICAL AND HEALTH EFFECTS EXECUTIVE If one
assumes
that the
mass
of fluorine
SUMMARY
(F)
deposited
under
an upper limit of 1.5x109 per year and all F returns as hydrogen into global rainfall and is deposited tation
would be about
by wet deposition,
steady-state
conditions
will have
fluoride (HF) that is uniformly
an upper limit for the concentration
dispersed
of F in precipi-
3 gg per liter (3 ppb).
This quantity of F, with reference to concentration or rate of deposition, is well below that heretofore considered to be of significance with respect to the direct effects on plants of air-borne F from industrial operations.
It also represents
(3 to 10 ppb). Moreover, tially no capacity cipally
a 30 to 100% increase
F at this concentration
to modify the chemical
determined
in what would be estimated
would be passively
speciation
of elements
by Ca or A1, and pH and concentration
the potential
of these elements
lower range
of pH should be sufficient
The wet deposition
to alter the activity
transported
of sulfate
F derived
of 3 ppb HF in rain and a total precipitation
as a complex
in rain. The activity
background with essen-
of F in rain is prin-
ions in precipitation
could affect
A1 concentrations
in rain at the
of F. Nevertheless,
to complex
to be natural
from the degradation
of fluorocarbons.
of 1000 mm per year would constitute
a negligible enrichment of the soil in terms of its normal contents or in comparison to that from perhaps the lowest detectable atmospheric concentration of gaseous F. Nor would this deposition of HF affect the chemistry
of acidic soils, and rain with a concentration
to affect the chemistry
of alkaline
some species
available
acetic acid, the effects cannot be estimated
on the effects or degradation
of plants can synthesize
Despite the great monofluoroacetate
would be needed
soils.
If one assumes that any or all F returns as a fluorinated no data are presently
of HF at least 103 greater
monofluoroacetate
of trifluoroacetic
acid in plants.
and omega-fluorooleate
because
Nevertheless,
and -fluoropalmitate.
chemical stability of the methylene carbon-fluorine bond, plants can metabolize and enzymes capable of degrading it occur in soil microorganisms. This leads to the
question of the ultimate
fate of trifluoroacetic
cal dehalogenation
and what end products
It is recommended
that research
acid with reference
to the possible
mechanisms
for biologi-
could occur.
be directed
to: (1) metabolism
of trifluoro-
and other halidoacetates
by
plants and microorganisms; (2) phytotoxicity of perchloroacetate and alkylhydroperoxides; (3) bioaccumulation and toxicology of these compounds in components of terrestrial and aquatic ecosystems; (4) further quantitative
knowledge
of the biogeochemistry
of F in natural
systems.
463 PRECEDING
P_GE
BL:_.!'_K NOT
FZL_,_ED
BIOLOGICAL AND HEALTH EFFECTS 1. ASSUMPTIONS The interaction of the degradation
products of fluorocarbons
by direct effects on the plant; by changes ate environment
of the plant.
mediated
For an assessment
to the nature of the environmental with the following boundaries.
exposures
with vegetation could occur in several modes:
by the plant; or indirectly, of any of these,
certain
that could be expected.
by an affect on the immediassumptions
are 0ecessary
as
Ours will be based upon an envelope
Firstly, we shall assume that the mass of fluorine deposited globally per annum under steady-state conditions will have upper and lower limits of 1.5x109 and 0.5x109 kg, respectively. These values are based on another assumption that upper and lower annual rates for global emissions of fluorocarbons are, respectively, 3x 109 and 1x l09 kg with fluorine constituting an average of 50% of the mass of the fluorocarbons. Secondly,
we shall assume that all fluorine
nated acetic acid. A subsidiary
assumption
(F) returns
either as hydrogen
currence of difluoromonochloroand monofluorodichloro-forms fluorine among them could be considered. Thirdly,
we shall assume
precipitation.
Concomitant
that fluorine assumptions
of 4.9x10 iv liters per year (Erchel, of fluorine
in precipitation
2. INORGANIC Concern (mainly
fluoride
(HF) or as a fluori-
is that the latter occurs as the trifluoro-form
is deposited
are that this is uniformly
dispersed
the oc-
and the partitioning
by the mode of wet deposition,
1975). Consequently,
would be, respectively,
are possibilities
although
of
i.e., by rainout
into an average
in
global rainfall
upper and lower limits for the concentration
3 and 1 /ag per liter (3 and 1 ppb).
FLUORINE
with the effects
with reference
of fluorides
on plants has been devoted
to gaseous HF and secondarily
tation as rain or mist and the presence
with paniculate
to that resulting forms).
of dew or free water on the foliage
from dry deposition
The occurrence
of precipi-
has mainly been considered
with respect to their effects on the accumulation of air-borne fluoride and not with fluoride in wet deposition. That is, precipitation has been viewed primarily with respect to its facilitation of the solution and subsequent absorption of deposits by the foliar tissues or its elution of deposited fluoride from foliage. (For example: the effects of mist on toxicity of HF and cryolite, McCune et al, 1977; models for the accumulation
of fluoride
by forage,
Craggs
and Davison,
1985).
Accordingly, our evaluation of inorganic fluoride from fluorocarbon degradation rests upon a comparison with what is known about the effects of industrial emissions and what could be considered the natural condition.
2.1.
HF in precipitation
One problem anthropogenic
is to what extent the concentration sources,
bons represent to the conclusion
of fluoride in rain can be partitioned
and then to what extent the products
an increased
burden
that the assumed
from the atmospheric
degradation
over that contributed
by the other sources.
quantities
in rain due to the degradation
of fluoride 464
into natural
In general,
and
of fluorocarone can come
of fluorocarbons
BIOLOGICAL ANDHEALTHEFFECTS may represent
close to the detectable
no effect on the chemistry
2.1.1.
of present
levels,
be deposited
as complexes,
and have
Quantity
In a metropolitan frequently
area (Yonkers,
were greater
considered enriched
increment
of rain water or on the plant.
New York),
than 50 ppb in rainfall
free of anthropogenic
influence
by a source (probably
fluoride
had fluoride
by washout)
concentrations
(Jacobson
et al.,
never exceeded
100 ppb and in-
1976). In Newfoundland,
rain and snow
averaging
had average
less than 10 ppb whereas
concentration
precipitation
of 280 ppb in rain (range
of 110
to 580 ppb) and an average of 360 ppb in snow water (range of 110 to 1040 ppb) (Sidhu, 1982). Barnard and Nordstrom (1982) found a difference between coastal and inland sites in the distribution of values. Coastal
values
ranged
concentrations;
inland values
from mass balance rather
from 2 to 24 ppb with a median of 4.2 ppb and were uncorrelated
than from maritime
2.1.2.
ported
as a complex
water.
Basically,
aerosols,
volcanic
has concluded
activity
of 9.4 ppb. They further
in precipitation
concluded,
was anthropogenic
(2 to 3 ppb), or soil particles
in origin
(ca 1 ppb).
ions determining
upon the pH. Above
in dust determine,
the activity
speciation
of elements
in rain
in addition
to quantity,
the ac-
pH 5.0, the solubility
of fluoride
than 4 by the formation
The solution of sulfate ions in precipitation to alter the activity of fluoride.
Nevertheless,
of fluorocarbons
will secondarily
would be Ca
of AI(III) regulate
limit its
nearly all fluoride
of AI-F complexes. affect Ca and AI and thereby
at the concentrations
would not alter the acidity
in solution
of Ca and other salts of fluoride
than 10 -4 M. Below pH 4.5, hydrates
of AI:F of greater
the degradation
to modify the chemical
and form of minerals
that the major
to a level no greater ratios
no capacity
present in rainfall, fluoride is passively trans-
in rain.
Ares also concluded or A1, depending
that at the concentrations
with essentially
the composition
tivity of fluoride
at molar
that most of the fluoride
Chemistry
Ares (unpublished)
activity
ranged up to 34 ppb with a median
considerations,
with sodium
of fluoride assumed,
or composition
their potential
HF derived
from
of rain.
That AI concentrations in rain should be sufficient to complex fluoride at the lower pH range is deduced from limited data. In the vicinity of GiSttingen, levels of A1 ranged from 48 to 174 ppb with a mean of 89 ppb (Ruppert, ranging
2.2.
from
1975). In the vicinity of Soiling,
10 to 1720 with a median
found concentrations
of A1 in rain
Effects on soil
The fluoride
content
of normal
soils ranges
depth in the soil, and content of organic son,
Ares (unpublished)
of 100 ppb.
1983). Assuming
a concentration
about 30 gF ha -1 would be deposited
matter,
from 20 to 1000 ppm depending with an average
465
present,
of about 200 ppm (see review by Davi-
of 3 ppb in rain and a total precipitation per year, which
upon minerals
is equivalent
of 1000 mm per year,
to an enrichment
of about 0.04 ppm
BIOLOGICAL ANDHEALTHEFFECTS (using Davison's
bulk density factor for soil). By comparison
and using Davison's
estimate
of deposition
velocity, exposure to air averaging 0.05/agF m -3 would result in the deposition of about 380 gF ha -t per year. Consequently, this wet deposition would constitute a negligible contribution to the soil in terms of normal contents or in comparison of gaseous fluoride.
to that from perhaps
the lowest detectable
atmospheric
concentration
The data of Ares (1986) would also indicate that wet deposition of HF in the assumed range of concentrations would not affect the soil solution in acidic forest soils. In these, it was estimated that 99.9% of fluoride was complexed with A1, and one could conclude that 3 ppb in rain would not affect the chemistry of the soil. Ares postulated that the solubility of fluoride in alkaline soils (pH 7.2 to 8.2) is controlled by ralstonite (NaMgAIF6) at high Na levels or fluorite (CaF2) at low Na levels and that rain with a concentration at least 103 greater than that assumed In areas subject to airborne soil chemistry
fluoride
have been observed
in this assessment
from industrial
would be needed to affect the soil chemistry.
emissions,
enrichment
of fluoride
(Ares, 1978; Fiuhler et al., 1982; Polomski
and changes
et al., 1982; Sidhu,
in
1982).
Nevertheless, it has been concluded that the increased levels of fluoride found in foliage in these areas represents more the result of increased deposition directly to the plant than of uptake from an increased level of fluoride in soil (Braen and Weinstein, 1985; McClenahen, 1976).
2.3.
Gaseous
HF
By way of comparison, the effects of gaseous fluoride are relatively well known although knowledge is not as plentiful as would be desired for practical applications to environmental quality. Table 1 lists some values for different averaging times of what could be considered protective for three classes of vegetation. Some standards for fluoride are also based on the concentration present in foliar tissue, and Table 2 presents a example of this kind of standard. The short-term or young foliage
(24-hour) value for highly sensitive plants is based upon the effects of HF on gladiolus of conifers, such as spruce, fir, and pine (see reviews by McCune, 1969; Weinstein,
1977). The l-month
Table
value for highly sensitive
plants represents
1. Possible acceptable limits for atmospheric with reference to effects on vegetation.
Plant
Low
concentrations
24 hours 1.6
466
for grapevines
of gaseous
Concentration
Sensitivity class High Moderate
what could be protective
_gF
fluoride
m-3)
Averaging time 1 month 7 months 0.4
0.25
3.6
1.5
0.6
10.0
2.5
1.2
BIOLOGICAL ANDHEALTHEFFECTS Table 2.
Standards
of the State
of Maryland
for the concentration
of fluoride
in
vegetation.
Concentration
Class of vegetation
of fluoride
(_gF per g dry mass) Forage
60 b
80 350
for cattle a
Field crops plants
400
Conifers & evergreens (current) .... (older) Deciduous trees & shrubs
500 1O0d
Grasses
1500
Ornamental
a) Unwashed
& herbs
35 c
75 d
(not grazed)
samples
b) Mean for two months c) Mean for 12 months d) Foliage
washed
before
analysis
based on the work of Doley
(1986) with the Chardonnay
cultivar
of Vitis vinifera.
The 7-month
concen-
tration for highly sensitive plants is based in part on the results of MacLean et al. (1984) as related to the occurrence of suture red spot (SRS) on fruit of peach. This is one of the most sensitive responses of plants to HF and also an economically is not of concern, The averaging to furnish
a higher periods
the experimental
significant
effect.
If protection
against
value such as 0.4 _gF m -3 based upon Doley
above were chosen data, However,
mainly because
they represent
they should also recognize
the occurrence
(1986)
could
the exposure
of SRS
be used. regimes
what characteristics
used
of exposure
could be operationally significant in the vicinities of the sources and receptors. Given the variability observed in the concentrations of HF in quotidian or weekly cycles and the temporal variations in the susceptibility of plants under ambient than 24 hours
conditions,
and less than 30 days.
whether a mean value is appropriate ived could be zero. In general one could conclude tive for vegetation wet deposition
3. HYDROGEN Although natives,
one could propose
With respect
periods
to a seven-month
shorter
value,
when the median of the population
that atmospheric
would result in greater
of HF from fluorocarbon
of fluoride
or greater
there is some question
of samples
levels of gaseous fluoride
accumulations
than 24 hours from which
below those considered
in foliage
as to
it is der-
protec-
and soil than would the
degradation.
CHLORIDE
hydrogen
chloride
could also result from degradation
it is much less toxic to plants than fluoride.
For example, 467
of some compounds Guderian
proposed
(1977) recommends
as altera concen-
BIOLOGICAL ANDHEALTHEFFECTS trations
no greater
concentrations
than 50 _g m -3 as being
of chloride
protective
in foliage associated
of the most sensitive
with thresholds
vegetation.
In addition,
for foliar injury are in the range of 0.2
to 2% by dry weight.
4. FLUORO-ORGANIC
COMPOUNDS
No data are presently
available
do synthesize monofluoroacetate and microbes.
of the effect of trifluoroacetic
acid on plants. Nevertheless,
and some data is available on the degradation
some plants
of this compound
by plants
The distribution of fluorine-containing organic molecules in nature appears to be limited to its occurrence as monofluoroacetate (Marais, 1944) and in omega-fluorine homologues, fluorooleate and fluoropalmitate (Peters (1972).
et al. 1960; Ward et al.,
The carbon-fluorine
accomplished
by refluxing
acid. Complete at 400C.
release
Monofluoroacetate thesis"
1964). For more details on their distribution
bond in these compounds in 20 percent
occurs
only after refluxing
is a naturally-occurring
in many mammals
which blocks aconitic
(Peters,
hydratase
or heating
in 30 percent
compound
stability
sodium hydroxide
is
sulfuric
or by sodium fusion
of monofluorocitrate
and can result in death. It seemed
et al.
and its slow release
at 100C in concentrated
in plants, and has been implicated
1952), i.e., the biosynthesis
stability of the methylene carbon-fluorine of the carbon-fluorine from a pseudomonad
has extraordinary
sodium hydroxide
see Weinstein
in "lethal
syn-
from fluoroacetate,
likely that, despite
the great chemical
bond, there might be enzymes capable of degrading
it. The cleavage
bond of monofluoroacetate was first reported by Horiuchi (1962) using extracts isolated from soil. Although defluorination occurred, significant defluorination was
not reported until Goldman (1965) isolated a pseudomonad from soil that grew on a medium containing monofluoroacetate as the sole carbon source. The results were quickly verified for other soil organisms (Tonomura
et al., 1965; Kelly,
haloacetate halidohydrolase lyzes the reaction
1965). The enzyme
(Goldman
and Milne,
XCH2COO" where
capable
of cleaving
1966; Goldman
+ OH" _
the carbon-fluorine
et al., 1968; Goldman,
bond was a
1969)that
cata-
X' + HOCH2COO"
X = F, CI, or I.
Preuss et al. (1968,
1969) first reported
that higher
plants can cleave
the methylene
carbon-fluorine
bond. This was shown by the liberation of t4CO2 following incubation with 2-_4C-fluoroacetate in germinating seeds of peanut, castor bean, and Acacia georginae. Pinto bean seeds were not able to liberate L4COE. In peanut, inorganic fluoride was one product of the reaction. The other was postulated acid. The enzyme that accomplishes defluorination in plants has not been characterized. The facility by which the carbon-fluorine isms and higher plants, one of the major probable
leads to the question
products
that plant and/or
of photochemical microbial
bond can be cleaved of the ultimate oxidation
enzymes can remove 468
by enzymes
to be glycolic
found in soil microorgan-
fate of trifluoroacetic
of several of the alternative
acid (Pattison,
1959),
fluorocarbons.
fluorine atoms from the molecule.
Whether
It is de-
BIOLOGICAL ANDHEALTHEFFECTS halogenation
will occur as it does with dichloroacetate
gen atoms together, product,
or whether
(Goldman
it might be a stepwise
et al., 1968), i.e., removal
dehalogenation,
with monohalidoacetate
of both haloas the end
is not known.
5. RECOMMENDATIONS It is apparent heretofore
that the quantities
considered
of inorganic
fluoride
assumed
in this discussion
to be of interest with respect to the environmental
are well below those
consequences
of industrial
opera-
tions. They could represent a doubling of what would be estimated to be natural background. ly, research on their possible biogeochemical effects should be directed to the identification
Accordingof natural
systems presently uninfluenced by anthropogenic and transformation for fluoride in them.
of transport
With reference to: (1) metabolism
to the effects of trifluoro-
of fluoro-organic
fluoride and a better understanding
compounds,
and other halidoacetates
tion and toxicology of these compounds in components of perchloroacetate and alkylhydroperoxides.
it is recommended
of pathways
that research be directed
by plants and microorganisms;
of terrestrial and aquatic ecosystems;
469
(2) bioaccumula(3) phytotoxicity
Annex
A
Experts
and Reviewers
PRECEDING
PI-_GE BL_.P,_K NOT
FILMED
ANNEX EXPERTS AND
A
REVIEWERS
INVOLVED
IN AFEAS
EXPERTS R. Atkinson
University
W.L. Chameides P.S. Connell
Georgia Institute of Technology Lawrence Livermore National Laboratory
R.A. Cox
Harwell
R.G. Derwent D.L. Filkin
Harwell Laboratory E. 1. du Pont de Nemours
& Co., Inc,
D.A.
E. 1. du Pont de Nemours
& Co., Inc.
Drexel University E. 1. du Pont de Nemours
& Co., Inc.
J.P. C.H.
Fisher Friend Hales
R.F. Hampson I.S.A. Isaksen L.S. Kaminsky M.K.W. Ko
of California,
Laboratory
National
Institute
Oslo University State University Atmospheric
Institute
D.C.
McCune
M.O.
McLinden
Boyce Thompson National Institute
University
and Technology,
and Environmental
National
H. Niki M.J. Prather
of Standards
Gaithersburg
of New York at Albany
M.J. Kurylo R. Lesclaux
M.J. Molina
Riverside
of Standards
Research,
Inc
and Technology,
Gaithersburg
of Bordeaux Institute for Plant Research, Ithaca of Standards and Technology, Boulder
Jet Propulsion Laboratory York University, Ontario NASA
Goddard
Institute
for Space Studies
V, Ramaswamy S.P. Sander
Princeton
F. Stordal
Oslo University
N.D.
Atmospheric Kfa Julich
and Environmental
Research,
Inc.
W-C Wang L.H. Weinstein
Atmospheric
and Environmental
Research,
Inc,
P.H. Wine D.J. Wuebbles
Georgia Institute of Technology Lawrence Livermore National Laboratory
R. Zellner
University
Sze
A. Volz-Thomas
University
Jet Propulsion
Boyce
Laboratory
Thompson
Institute
for Plant Research,
Ithaca
of Hannover
REVIEWERS D.L.
Albritton
National
Oceanic
J.G.
Anderson
Harvard
University
R.E.
Banks
J.J. Bufalini
University of Manchester Institute of Science US Environmental Protection Agency
A.W,
Davison
Newcastle
W.B. D.D.
DeMore Des Marteau
Jet Propulsion Clemson
and Atmospheric
University Laboratory
University
R.A. Duce
University
of Rhode Island
A. Goldman
University
of Denver A-1
Administration and Technology
EXPERTS M.R. Hoffman C.J. Howard N. Ishikawa J.L. Moyers V. Ramanathan A.R. F.S.
Ravishankara Rowland
AND
REVIEWERS
California
Institute
INVOLVED
National University
(Continued)
of Technology
National Oceanic and Atmospheric F&F Research Centre, Tokyo National Science Foundation University
IN AFEAS
Administration
of Chicago Oceanic
and Atmospheric
of California,
Administration
Irvine
P. Simon
Institut d'Aeronomie
H.O. Spauschus S. Solomon
Georgia Institute of Technology National Oceanic and Atmospheric
Administration
A. Tuck
National
Oceanic
Administration
R.T.
National Harvard
Aeronautics University
Watson
S. Wofsy
Spatiale
de Belgique
and Atmospheric
and Space Administration
A-2
Annex
B
Companies
Sponsoring
AFEAS
ANNEX COMPANIES
B
SPONSORING
AFEAS
Akzo Chemicals
Netherlands
Allied-Signal Asahi Glass Atochem
USA
Chemical
Corporation Co., Ltd.
Industries
of Northern
Daikin Industries, Ltd, E. I. du Pont de Nemours Hoechst
Japan France Greece,
Greece
S.A.
Japan USA
& Co., Inc.
Germany UK
AG
ICI Chemicals and Polymers ISC Chemicals Kali-Chemie AG LaRoche
Ltd.
UK Germany USA
Chemicals
Montefluos SpA Pennwalt Corporation
Italy USA
Racon
USA
(Atochem)
B-1
Annex
C
Statement
of Work
PRE.CEDING
PI'I.GEBLh._',_K NOT
FILMED
ANNEX C STATEMENT
Each reviewer the following. possible
should prepare
The reviews
and fifty copies
The reviews 1. Is there
of the reviews
3. Are the findings
supported
reported
of each paper of the AFEAS
should be brought
the following
information
2. Are the conclusions
review
should be sent to the chairman
should address significant
a one page written
OF WORK
specified science
to the AFEAS
with their name
committee
conference.
questions:
relevant
to the subject
by the information
in the executive
summary
that is not included
in the review
presented
in the review
supported
by the information
paper?
paper? in the body of the
paper? Are all of the important points covered in the executive summary? Does the summary vide the correct level of detail or is information included that should be removed? I. Physical and Chemical Properties: Since model calculations and evaluations information to submit A.
developed
in these reviews
their review
Solubility
Based on information
of potential
biological
as input, Experts
Vapor
Pressure,
in the literature,
Hydrolysis
supplied
pro-
and health effects will require the
answering
papers by not later than 28 February,
in Water,
in
as early as
these questions
will be required
1989.
Rates
by AFEAS
member
companies
and available
from
other sources, what are the recommended temperature dependent values of the solubility in pure water, solubility in sea water, vapor pressure, and hydrolysis rates for each of the HCFCs and HFCs? Expert - Mark McLinden Reviewer B.
- H.O.
Reaction
Spauschus
Rate Constants
Based on available for reaction
information,
on these rate constants? Reviewers C.
D.
- Bob Hampson,
temperature
dependent
rate constant
and O(_D)? What are the error limits
Mike Kurylo
and Stan Sander working
together.
and A. R. Ravishankara
information,
in the 8 - 13 m range)
limits on these cross-sections?
Reviewers
and HFCs with hydroxyl
Cross-Sections
Based on available error
Experts
- W. B. DeMore
Absorption
(primarily
what is the recommended
of each of the HCFCs
what are the recommended cross-sections Expert
ultraviolet
(190-400
for each of the HCFCs
- Mario
nm) and infra-red
and HFCs?
What are the
Molina
- P. Simon and A. Goldman
Degradation
Mechanisms
Based on available
information,
how will the HCFCs C-1
and HFCs degrade
in the troposphere
after
the initial hydrogen
atom abstraction
what is the most likely atmospheric ble fluorine-containing the atmosphere? experts,
lifetime
intermediates
Roger
Reviewers
what are the intermediate
of each of these products?
would be formed?
As this is one of the more important
are being asked to address
together;
by hydroxyl,
Atkinson;
these questions.
Hiromi
- All reviewers
should compare
and
Is it likely that relatively
How would the products set of questions,
Experts
Niki; and Reinhardt
and final products be removed
four experts,
stafrom
or teams
- Tony Cox and R. Lesclaux
of
working
Zellner.
the papers to identify
inconsistencies
and determine
if
they are due to uncertainties that cannot be resolved without further research or if they are due to errors in one or more of the papers. Specific responsibilities for more extensive reviews
are:
J. G. Anderson J. Bufalini
- papers
- papers
W. B .DeMore
prepared
- papers
A.R. Ravishankara
prepared
by R. A. Cox and R. Lesclaux
by R. Atkinson
prepared
and R. Zellner
and H. Niki
by H. Niki and R. Zellner
- papers prepared
by R. Atkinson
and R. A. Cox and R. Lesclaux
Each of the following reviewers should prepare a single review of the group of four papers. The group should be reviewed for completeness and consistency. Causes of any inconsistencies should be discussed. Each of these reviewers
should suggest a single executive summary
based on the four executive summaries.
F. S. Rowland R. E. Banks N. Ishikawa II.
Uncertainties
in Atmospheric
Experts answering 1 April, A.
Lifetimes
these questions
will be required
to submit their review papers by not later than
1989.
Tropospheric
Hydroxyl
Based on measurements
Concentrations of the isotopic
ratio of carbon in atmospheric
carbon
monoxide,
what is
the average tropospheric hydroxyl radical concentration and what are the uncertainties in the derived concentration? Given that the rate constant of the reactions of HCFCs and HFCs with hydroxyl are temperature the HCFCs
dependent, what is your best estimate of lifetime (with uncertainty limits) of each of and HFCs? Experts - Andreas Volz-Thomas and R. G. Derwent working together.
Given the available
data base on methyl chloroform
centrations
and estimated
compounds
and how sensitive
global emissions), are the lifetime
and HCFC-22
what are the calculated to variations 12-2
(measured atmospheric
atmospheric lifetimes
in these data, e.g. latitudinal,
con-
of these seasonal,
vertical profile? Assuming
Calculate
that reaction
the effect of a reasonable
variation in each of these parameters
with OH is the only sink for methyl chloroform
and HCFC-22,
in turn.
how do un-
certainties in the data base for these compounds extrapolate to influence the derived OH concentration? Extend the sensitivity calculation from effect on lifetime to effect on *OH* and hence on the lifetimes
of alternative
(with uncertainty Are the inferred reaction e.g.
fluorocarbons.
limits) of each of the HCFCs lifetimes
what is your best estimate
hydrolysis
for methyl chloroform
of methyl chloroform?
- S. Wofsy
Individual
reviews
and HCFC-22
compared.
If there are inconsistencies
that cannot
Expert
should be prepared
be resolved
without
- Michael
for each paper the reviewer
further
of lifetime
and HFCs. consistent
with OH is the only sink? Is it possible that there is another
Reviewer
B.
Based on this analysis,
research
with the assumption
that
sink for one or other compound,
Prather
and the conclusions
should determine
of the papers
should be
if they are due to uncertainties
or if one or both of the papers
contain
errors.
Hydrolysis Based on available
information
of methyl chloroform, of average
hydroxyl
on hydrolysis
HCFC-22 concentrations
derived
is being asked to determine
and HFCs
using measurements
the assumption that there are no other significant working
rates, what are the most likely atmospheric
and the other HCFCs atmospheric
if that is a valid assumption.)
against
hydrolysis?
of methyl chloroform
sinks of methyl chloroform. Experts
lifetimes (Estimates
are based on This question
- Paul Wine and Bill Chameides
together.
What are the atmospheric are the ultimate products working
lifetimes
of the compounds
that would be formed
identified
in solution?
in I.D.
against hydrolysis?
What
Experts - Paul Wine and Bill Chameides
together.
Reviewers
- M. R. Hoffmann
In addition
to preparing
potentially
important
and D. D. Des Marteau
reviews
of the papers the reviewers
liquid phase reactions
involving
should prepare
compounds
identified
brief summaries
of other
in I.D. and not addressed
by AFEAS. III. Natural
Sources
Experts answering 1 May,
these questions
will be required
to submit their review
paper by not later than
1989.
What are the source strengths and atmospheric concentrations of compounds containing chlorine and/or fluorine due to natural sources? What are natural concentrations of fluoride in ground water? What are the concentrations rivers,
of fluoride from natural sources in rain water and surface waters (oceans,
lakes)? What concentrations
are found in metropolitan
dation? What are the source strengths ic compounds Reviewers
in the atmosphere?
- J. L. Moyers
of other inorganic
Expert
- J. Friend
and R. A. Duce C-3
water supplies
compounds
before and after fluori-
that would be converted
to acid-
IV. ModelCalculations Expertsanswering thesequestions will berequiredto submittheirreviewpapersby notlaterthan 1 May, 1989. A. Stratospheric Ozone Giventheinformationsuppliedby theexpertsanswering I.B., I.C. andII., whatarethecalculated ozonedepletionpotentials (includinguncertainties) of theHCFCs?Basedonavailableinformation, couldHFCscontributeto ozonedepletion? Experts- DonFisher,IvarIsaksen,DakSzeandDon Wuebblesworkingtogether. Reviewers
- S. Solomon
B. Tropospheric
and A. F. Tuck
Ozone
Given the information
supplied by the experts answering
I.B., is it likely that the HFCs and HCFCs
would contribute to production of photochemical oxidants sis, how would emissions of HCFCs and HFCs (currently, kilograms
per year) compare
Reviewer
- J. Bufalini
C.
to natural
sources
in the vicinity of release? on a global baemissions of CFCs are about one billion
of ozone precursors?
Expert
- Hiromi
Niki.
Global Warming Given the information
bon global warming Don Fisher, Reviewer
potentials
by the experts (including
answering
uncertainty
Dak Sze, and one other climate
I.B., I.C. and II., what are the halocar-
limits) of the HCFCs
modeler,
working
and HFCs?
Experts
-
together.
- V. Ramanathan
V. Biological
and Health
Experts I May,
supplied
answering
Effects these questions
will be required
to submit their review papers by not later than
1989.
Based on the answers to these questions in sections I. and II., is it likely that the decomposition products from annual emissions of one billion kg. (an amount that is approximately equal to current emissions
of CFCs) could contribute
should range from humans lowing topics
to biological
or health effects?
all the way down to microorganisms.
for each of the classes
of degradation
1. Known acute and chronic affects to all concentrations, tions for which data are available. 2. Existence
of a dose-response
of data on quantitative
4. Biochemists
reaction
mechanisms,
dose-response if known. C-4
to be considered
The review should address
compounds
the fol-
on the list:
but with emphasis on the lowest concentra-
threshold.
3. Availability
The organisms
relationships.
5. Repair 6. Potential
mechanisms
7. Most important
Reviewer Individual
ability of the organism
effects at projected
parent compound
Experts
and/or
concentrations
of 1 billion kg/year research
- L. S. Kaminsky;
needed
to adapt.
corresponding
at steady
to resolve
uncertainties
and L. H. Weinstein
to hypothetical
emissions
for a given
state. relevant
to the above items.
and D. C McCune
working
together.
- A. Davison reviews
should be prepared
for each paper
and the conclusion
of the papers
should be
compared. If there are inconsistencies the reviewer should determine if they are due to uncertainties that cannot be resolved without further research or if one or both of the papers contain errors.
C-5
ili!i!i_
'
i!iii!i!iiii:_ii i
REFERENCES
REFERENCES
AFEAS
REFERENCE
LIST
Adachi, H., and N. Basco, Kinetic spectroscopy study NO, Chem. Phys. Lett., 64,431-434, 1979a. Adachi, H., and N. Basco, The reaction Lett., 67, 324-328, 1979b. Adachi, H., and N. Basco, Reactions J. Chem. Kinet., 14, 1243-1251, Addison,
M. C., R. J. Donovan,
halogenomethanes, Afanassiev, reaction
Faraday
A. M., K. Okazaki, rates in hydroxylic
of ethylperoxy
Disc.
radicals
of isopropylperoxy 1982.
and J. Garraway, Chem.
Soc.,
of the reaction
with NO2,
radicals
Reactions
of C2H502
Phys.
with NO and NO2, Int.
of O(1D)
67, 286-296,
Chem.
with
and O(3p)
with
1979.
and G. R. Freeman, Effect of solvation energy on electron solvents, J. Phys. Chem., 83, 1244-1249, 1979.
Airaksinen, M. M., and T. Tammisto, Toxic actions of the metabolites of halothane: LD50 and some metabolic effects of trifluorethanol and trifluoroacetate acid in mice and guinea
pigs, Ann.
Med.
Exp. Fenniae,
46, 242-248,
Airaksinen, M. M., P. H. Rosenberg, and T. Tammisto, of trifluoroethanol and other halothane metabolites, 304,
1968. A possible mechanism of toxicity Acta Pharmacol. Toxicol., 28, 299-
1970.
Alfassi, Z. B., S. Mosseri, and P. Neta, Halogenated Effects of solvents and of substituents on rates 91, 3383-3385, 1987.
alkyl peroxyl radicals as oxidants: of electron transfer, J. Phys. Chem.,
Allied-Signal Corporation, unpublished data, private R. G. Richard, Buffalo, NY, 1989.
communication
with S. R. Orfeo
and
Ambrose, D., D. H. S. Sprake, and R. Townsend, Thermodynamic properties of aliphatic halogen compounds, part 1 -- vapour pressure and critical properties of 1,1,1trichloroethane, J. Chem. Soc., Faraday Trans. 1, 69, 839-841, 1973. Anastasi, C., D. J. Waddington, and A. Woolley, Reactions of oxygenated radicals in the gas phase. Part 10 - Self reactions of ethylperoxy radicals, J. Chem. Soc., Faraday Trans. 1, 79, 505-506, 1983. Anastasi, C., I. W. M. Smith, and D. A. Parkes, Flash photolysis study of the spectra of CH302 and C(CH3)302 radicals and the kinetics of their mutual reactions and with NO, J. Chem. Soc., Faraday Trans. 1, 74, 1693-1701, 1978. Anbar, M., and E. J. Hart, The reaction of haloaliphatic electrons, J. Phys. Chem., 69, 271-274, 1965.
compounds
with hydrated
Andon, R. J. L., J. F. Counsell, D. A. Lee, and J. F. Martin, Thermodynamic properties of aliphatic halogen compounds, part 2 -- Heat capacity of 1,1,1-trichloroethane, J. Chem. Soc., Faraday Trans. 1, 69, 1721-1726, 1973.
R-1
REFERENCES Ares, J. O., Fluoride cycling 28, 344-349, 1978.
near a coastal
emission
source,
J. Air Pollut.
Control
Assoc.,
Ares, J. O., Identification of aluminum species in acid forest soil solution on the basis of AI:F reaction kinetics: 2. An example at the Soiling area, Soil Sci., 142, 13-19, 1986. Artaxo, P., H. Storms, F. Bruynseels, R. Van Grieken, and W. Maenhaut, Composition and sources of aerosols from the Amazon Basin, J. Geophys, Res., 93, 1605-1615, 1988. ASHRAE, ASHRAE Handbook of Fundamentals, Refrigerating, and Air-Conditioning Engineers, ASHRAE, ASHRAE Thermodynamic Properties Heating, Refrigerating, and Air-Conditioning
American Atlanta,
Society 1985.
of Heating,
of Refrigerants, American Society Engineers, Atlanta, 1987.
of
Atkinson, R., Kinetics and mechanisms of the gas-phase reaction of the hydroxyl radical with organic compounds under atmospheric conditions, Chem. Rev., 86, 69-201, 1986. Atkinson, R., A structure-activity relationship for the estimation gas-phase reactions of OH radicals with organic compounds, 799-828, 1987. Atkinson, R., Gas-phase tropospheric chemistry Atmos. Environ., in press, 1989a. Atkinson, R., Kinetics and mechanisms with organic compounds, J. Phys.
of organic
compounds:
of the gas-phase reactions Chem. Ref. Data, in press,
Atkinson, R., and A. C. Lloyd, Evaluation photochemical smog, J. Phys. Chem.
A review,
of the hydroxyl 1989b.
radical
of kinetic and mechanistic data for modeling Ref. Data, 13, 315-444, 1984.
Atkinson, R., and S. M. Aschmann, Kinetics of the gas phase series of organics at 296+ 2 K and atmospheric pressure, 41, 1985. Atkinson, R., and W. P. L. Carter, ozone with organic compounds 470, 1984.
of rate constants for the Int. J. Chem. Kinet., 19,
of
reactions of C1 atoms with a Int. J. Chem. Kinet., 17, 33-
Kinetics and mechanisms of the gas-phase reactions of under atmospheric conditions, Chem. Rev., 84, 437-
Atkinson, R., D. A. Hansen, and J. N. Pitts, Jr., Rate constants for the reaction of OH radicals with CHF2C1, CF2C12, CFCI3, and H2 over the temperature range 297-434 J. Chem. Phys., 63, 1703-1706, 1975. Atkinson, R., D. L. Baulch, R. A. Cox, R. F. Hampson, J. A. Kerr, and J. Troe, Evaluated kinetic and photochemical data for atmospheric chemistry: Supplement Int. J. Chem. Kinet., 21, 115, 1989.
III,
Atkinson, R., D. L. Baulch, R. A. Cox, R. F. Hampson, Jr., J. A. Kerr, and J. Troe, Evaluated kinetic and photochemical data for atmospheric chemistry. Supplement III, J. Phys. Chem Ref. Data, 18, 881-1097, 1989.
R-2
K,
REFERENCES Atkinson,
R., G. M. Breuer,
J. N. Pitts,
Jr., and H. L. Sandoval,
stratospheric sinks for halocarbons: Photooxidation, reactions, J. Geophys. Res., 81, 5765-5770, 1976.
O(1D)
Tropospheric atom,
and
and OH radical
Atkinson, R., S. M. Aschmann, and A. M. Winer, Alkyl nitrate formation from the reaction of a series of branched RO2 radicals with NO as a function of temperature pressure,
J. Atmos.
Chem.,
5, 91-102,
and
1987.
Atkinson, R., S. M. Aschmann, W. P. L. Carter, A. M. Winer, and J. N. Pitts, Jr., Alkyl nitrate formation from the NOx-air photo-oxidations of C2-C8 n-alkanes, J. Phys. Chem., 86, 4563-4569, 1982. Auerbach, I., F. H. Verhoek, and A. L. Henne, sodium trifluoroacetate in ethylene glycol,
Kinetics studies on the decarboxylation J. Am. Chem. Soc., 72,299-300, 1950.
Baden, J. M., M. Brinkenhoff, R. S. Wharton, Mazze, Mutagenicity of volatile anesthetics: 1976.
B. A. Hitt, V. F. Simmon, Halothane, Anesthesiology,
Bahnemann, D. W., C. Kormann, and M. R. Hoffman, quantum size zinc oxide: A detailed spectroscopic 3798, 1987.
of
and R. I. 45, 311-318,
Preparation and characterization study, J. Phys. Chem., 91, 3789-
of
Baker, J. W., and D. M. Easty, Hydrolytic decomposition of esters of nitric acid. Part I. General experimental techniques. Alkaline hydrolysis and neutral solvolysis of methyl, ethyl, isopropyl, and tert-butylnitrates in aqueous alcohol, J. Chem. Soc., 1193-1207, 1952. Balkas, T. I., The radiolysis of aqueous Phys. Chem, 4, 199-208, 1972.
solutions
of methylene
Balkas, T. I., J. H. Fendler, and R. H. Schuler, Radiolysis chloride. The concentration dependence of scavenging Chem, 74, 4497-4505, 1970.
chloride,
Int. J. Radiat.
of solutions of methyl electrons within spurs,
Balkas, T. I., J. H. Fendler, and R. H. Schuler, The radiation solutions of CFC13, CF2C12, and CF3C1, J. Phys. Chem,
J. Phys.
chemistry of aqueous 75,455-466, 1971.
Balla, R. J., H. H. Nelson, and J. R. McDonald, Kinetics of the reactions radicals with NO, NO2, and 02, Chem. Phys., 99, 323-335, 1985.
of isopropoxy
Ballinger, P., and F. A. Long, Acid ionization constants of alcohols. II. Acidities of some substituted methanols and related compounds, J. Am. Chem. Soc., 82,795-798, 1960. Barnard,
W. R., and D. K. Nordstrom,
geochemical
cycling
Batt, L., The gas phase 1977. Batt, L., Reactions 1987.
of fluorine,
Fluoride Atmos.
decomposition
of alkoxy
and alkyl
in precipitation.
Environ.,
of alkoxy
peroxy
R-3
16, 105-111,
radicals,
radicals,
II. Implications 1982.
Int. J. Chem.
Int. Rev.
for the
Phys.
Kin.,
Chem.,
11,977,
6, 53-90,
REFERENCES Batt, L., and R. Walsh, A reexamination of the pyrolysis of bis trifluoromethyl peroxide. Addendum: Concerning D(CF302-CF3) and D(CF3-O2), Int. J. Chem. Kinet., 15, 605-607, 1983. Batt, L., M. MacKay, I. A. B. Reid, and P. Stewart, The pressure dependent decomposition of the trifluoromethoxy radical, 9th International Symp. Gas Kinetics, University of Bordeaux, Bordeaux, France, July 20-25, 1986. Baulch, D. L., R. A. Cox, P. J. Crutzen, R. F. Hampson, Jr., J. A. Kerr, J. Troe, T. Watson, Evaluated kinetic and photochemical data for atmospheric chemistry: Supplement I, J. Phys. Chem. Ref. Data, 11,327-496, 1982.
and
R.
Baulch, D. L., R. A. Cox, R. F. Hampson, Jr., J. A. Kerr, J. Troe, and R. T. Watson, CODATA Task Group on Chemical Kinetics, Evaluated kinetic and photochemical data for atmospheric chemistry, J. Phys. Chem. Ref. Data, 11,327-496, 1982; 13, 12591380, 1984. Baulch, D. L., R. A. Cox, R. F. Hampson, Jr., J. A. Kerr, J. Troe, and R. T. Watson, Evaluated kinetic and photochemical data for atmospheric chemistry, J. Phys. Chem. Ref. Data, 9, 295-471, 1980. Beilsteins Benson,
Handbuch
der Organischen
S. W., Thermochemical
Berdnikov, radicals
Chemie,
Kinetics,
Vierte
Auflage,
2nd ed., Wiley,
V. M., and N. M. Bazhin, Oxidation-reduction in aqueous solutions, Russ. J. Phys. Chem.
Bemstein, P. A., F. A. Hohorst, and D. D. DesMarteau, Properties and reactions with some acid fluorides, 1971.
Springer,
New
York,
1960. NY,
potentials of certain inorganic Engl. Trans., 44,395-398, 1970. Trifluoromethyl hydroperoxide. J. Am. Chem. Soc., 93, 3883-3886,
Bertrand, L., J. A. Franklin, P. Goldfinger, and G. Huybrechts, The point chlorine atom of trichloroethylene, J. Phys. Chem., 72, 3926, 1968. Betrand, L., L. Exsteen-Meyers, J. A. Franklin, photosensitized oxidations of chloroethanes J. Chem. Kin., 3, 89, 1971.
1976.
of attack
of a
G. Heubrecht, and J. Olbregts, Chlorine and chloroethylenes in the gas phase, Int.
Betterton, E. A., and M. R. Hoffman, Henry's law constants for some environmentally important aldehydes, Environ. Sci. Technol., 22, 1415-1418, 1988. Bewers, J. M., and H. H. Haysom, The terrigenous dust contribution iodide in atmospheric precipitation, J. Rech. Atmos., 13,689-697, Bewers, J. M., and P. A. Yeats, Fluoride Oceanography, 20, 149-150, 1975.
in global
circulation,
Limnology
Bielski, B. H. J., Reevaluation of the spectral and kinetic properties radicals, Photochem. Photobiol., 28, 645-649, 1978. Blake, D. A., H. F. Cascorbi, trifluoroethanol, Toxicol.
to fluoride 1974. and
of HO2 and O2-free
R. S. Rozman, and F. J. Meyer, Animal Appl. P harmacol., 15, 83-91, 1969.
R-4
and
Toxicity
of 2,2,2-
REFERENCES Blake, D. A., M. C. DiBlasi, and G. B. Gordon, Absence of mutagenic activity trifluoroethanol and its metabolites in salmonella typhimurium, Fund. Appl. 1,414-418, 1981.
of Toxicol.,
Blake, D. A., V. H. Woo, S. C. Tyler, and F. S. Rowland, Methane concentrations and source strengths in urban locations, Geophys. Res. Lett., 11, 1211-1214, 1984. Bonsang, B., and G. Lambert, Nonmethane Chem., 2,257-271, 1985.
HC in an oceanic
atmosphere,
Braen, S. N., and L. H. Weinstein, Uptake of fluoride and aluminum contaminated soils, Water Air Soil Pollut., 24, 215-223, 1985. Brimblecombe, P., and S. L. Clegg, The solubility and behavior marine aerosol, J. Atmos. Chem., 7, 1-18, 1988. Buat-Menard, particulate 1974. Bullock, Soc.,
P., J. Morelli, matter
and R. Chesselet,
over tropical
and equatorial
G. and R. Cooper, Reactions 66, 2055-2064, 1970.
Bunton, C. A., and J. H. Fendler, 2307-2312, 1966.
Water-soluble
of aqueous
The hydrolysis
Atlantic,
Calvert,
J. G., and J. N. Pitts,
Jr., J. Photochemistry,
in
in the
in atmospheric
J. Res. Atmos.,
radicals,
fluoride,
grown
8, 661-673,
Trans.
Far.
J. Org. Chem.,
31,
in the essential oil of alga Lett., 7, 473-476, 1975. Wiley,
Caralp, F., A. M. Dognon, and R. Lesclaux, 8th International Kinetics, University of Nottingham, Nottingham, U.K., Caralp, F., and R. Lesclaux, oxygen in the pressure 1983.
of acid gases
trifluoromethyl
Burreson, B. J., R. E. Moore, and P. Roller, Haloforms Asparagopsis taxiformis (rhodophyta), Tetrahedron
by plants
elements
of acetyl
J. Atmos.
New
York,
Symposium July 15-20,
1967. on Gas 1984.
Rate constant for the reaction of the CFC12 radical with range 0.2-12 torr at 298 K, Chem. Phys. Lett., 102, 54-58,
Caralp, F., R. Lesclaux, and A. M. Dognon, Kinetics of the reaction the temperature range 233-373 K, Chem. Phys. Lett., 129, 433,
of CF3 with 02 over 1986.
Caralp, F., R. Lesclaux, M.-T. Rayez, J.-C. Rayez, and W. Forst, Kinetics of the combination reactions of chlorofluoromethylperoxy radicals with NO2 in the temperature range 233-373 K, J. Chem. Soc., Faraday Trans. 2, 84,569-585, Caralp, F., R. Lesclaux, M.-T. Faraday Trans. 2, 84,429,
Rayez, 1988b.
J.-C. Rayez,
and W. Forst,
J. Chem.
Soc.,
Carr, R. W., Jr., D. G. Peterson, and F. K. Smith, Flash photolysis of 1,3dichlorotetrafluoroacetone in the presence of oxygen. Kinetics and mechanisms oxidation of the chlorodifluoromethyl radicals, J. Phys. Chem., 90, 607-614,
R-5
1988a.
of the 1986.
REFERENCES Carter, W. P. L., and R. Atkinson, 3,337-405, 1985.
Atmospheric
chemistry
of alkanes,
J. Atmos.
Carter, W. P. L., and R. Atkinson, Alkyl nitrate formation from the atmospheric photooxidation of alkanes: A revised estimation method, J. Atmos. Chem., 173, 1989.
Chem.,
8, 165-
Cattell, F. C., J. Cavanagh, R. A. Cox, and M. E. Jenkin, A kinetics study of reactions of HO2 and C2H502 using diode laser absorption spectroscopy, J. Chem. Soc., Faraday Trans. 2, 82, 1999-2018, 1986. Chameides, W. L., The photochemistry Res., 89, 4739-4755, 1984. Chameides, Chem.
of a remote
W. L., and D. D. Davis, Chemistry and Eng. News, 60, 38-52, 1982.
Chameides, methane,
marine
stratiform
in the troposphere,
W. L., S. C. Liu, and R. C. Cicerone, J. Geophys. Res., 82, 1795, 1977.
Possible
cloud,
Special
variations
J. Geophys.
Report
in
in atmospheric
Chang, J. S., and F. Kaufman, Kinetics of the reactions of hydroxyl radicals with some halocarbons: CHFCI2, CHF2CI, CH3CC13, C2HC13, and C2C14, J. Phys. Chem., 66, 4989-4994, 1977. Chemical CFC
Manufacturers Association, CMA, Production, 11 and CFC 12 through 1982, 1983.
sales and calculated
release
of
Chemical CFC
Manufacturers Association, CMA, Production, 11 and CFC 12 through 1983, October, 1984.
sales and calculated
release
of
Chemical CFC
Manufacturers Association, CMA, Production, 11 and CFC 12 through 1987, 1988.
sales and calculated
release
of
Chert, S. S., A. S. Rodgers, J. Chao, R. C. Wilheit, thermodynamic properties of six fluoroethanes, 1975.
and B. J. Zwolinski, Ideal gas J. Phys. Chem. Ref. Data, 4, 441,
Cherneeva, L. I., Experimental investigation of the thermodynamic 142, Teploenergetika 1958(7), 38-43, 1958. Chesselet, R., J. Morelli, and P. Buat-Menard, Some aspects marine aerosols, The Changing Chemistry of the Oceans, eds., 94-120, John Wiley, New York, 1972. Cicerone, 1981.
R. J., Halogens
in the atmosphere,
Rev.
Geophys.
properties
of the geochemistry of D. Dryssen and D. Jagner,
Space
Phys.,
Clegg, S. L., and P. Brimblecombe, The dissociation constant and Henry's of HC1 in aqueous solution, Atmos. Environ., 20, 2483-2485, 1986. Clemitshaw, K. C., and J. R. Sodeau, Atmospheric study of the reaction between CF302 radicals 3653, 1987.
R-6
of Freon
19, 123-139,
Law
constant
chemistry at 4.2 K: A matrix isolation and NO, J. Phys. Chem., 91, 3650-
REFERENCES Clyne,
M. A. A., and P. M. Holt, Reaction
A25 -'. hydroxyl reactions 569-581, Clyne,
radicals.
of OH X2II 1979a.
kinetics
Part 1. Quenching wth CH3CC13
involving
kinetics
kinetics
X2I'I
and excited
of OH A2Y_ and rate constants
and CO, J. Chem.
M. A. A., and P. M. Holt, Reaction
ground
Soc. Faraday
involving
ground
Trans.
for
2, 75,
X2I'I and excited
A2Y. hydroxyl radicals. Part 2. Rate constants for reactions of OH X21-I wth halogenomethanes and halogenoethanes, J. Chem. Soc. Faraday Trans. 2, 75, 582591, 1979b. Cohen, N., and K. R. Westberg, Chemical chemical reactions, vol. II, Aerospace
kinetic Report
data sheets for high-temperature No. ATR-88(7073)-3, Nov. 14, 1988.
Cohen, N., and S. W. Benson, Transition-state-theory calculations for reactions with haloalkanes. I. Halomethanes, Aerospace Report No. ATR-85(7072)-1, Aerospace Corporation, E1 Segundo, CA, 1985.
of OH I, The
Cohen, N., and S. W. Benson, Transition-state-theory calculations for reactions with haloalkanes. I. Haloethanes, Aerospace Report No. ATR-85(7072 )-l, Aerospace Corporation, E1 Segundo, CA, 1985.
of OH H, The
Cooper, R., J. B. Cumming, S. Gordon, and W. A. Mulac, The reactions of the halomethyl radicals CC13 and CF3 with oxygen, Radiat. Phys. Chem., 16, 169, 1980. Cox, R. A., Tropospheric Ozone - Regional & Global Scale Interactions, Series C, vol. 227, ed. I. S. Isaksen, D. Reidel, Dordrecht, 1988. Cox, R. A., and G. S. Tyndall, Rate constants Chem. Phys. Lett, 65, 357-360, 1979.
for reactions
of CH302
NATO
ASI
in the gas phase,
Cox, R. A., and G. S. Tyndall, Rate constants for the reactions of CH302 with HO2, NO, and NO2 using molecular modulation spectrometry, J. Chem. Soc., Faraday Trans. 2, 76, 153-163, 1980. Cox,
R. A., and M. J. Roffey,
Cox, R. A., R. G. Derwent, oxidation of halocarbons,
Environ.
Sci. Technol,
A. E. J. Eggleton, Atmos. Environ.,
11,900,
1977.
and J. E. Lovelock, Photochemical 10, 305-308, 1976.
Craggs, C., and A. W. Davison, The effect of simulated rainfall on grass fluoride concentrations, Environ. Pollut. (Series B), 9, 309-318, 1985. Crutzen, P. J., Tropospheric ed., Reidel, Dordrecht,
ozone: Holland,
Crutzen, P. J., The global distribution Springer-Verlag, Berlin, 313-328, Crutzen, P. J., Photochemical tropospheric air, Tellus,
An overview, 3-32, 1988. of hydroxyl, 1982.
reactions initiated 26, 47-57, 1974.
Tropospheric
Atmos.
Chem.,
by and influencing
Crutzen, P. J., The possible importance of CSO for the sulphate Geophys. Res. Lett., 3, 73-76, 1976.
R-7
Ozone,
I. S. A. Isaksen,
E. D. Goldberg,
ozone
layer
ed.,
in unpolluted
of the stratosphere,
REFERENCES Crutzen, P. J., The role of NO and NO2 in the chemistry of the stratosphere troposphere, Annual Rev. Earth Planet Sci., 7, 443-472, 1979.
and
Crutzen, P. J., and L. T. Gidel, A two dimensional model of the atmosphere, 2. The tropospheric budgets of the anthropogenic chlorocarbons, CO, CH4, CH3C1, and the effect of various NOx sources on tropospheric ozone, J. Geophys. Res., 88, 1983. Crutzen, P. J., and J. Fishman, Average concentrations budgets of CH4, CO, H2, and CH3CC13, Geophys.
of OH in the troposphere, Res. Lett., 4, 321-324,
and the 1977.
Cunnold, D. M., R. G. Prinn, R. A. Rasmussen, P. G. Simmonds, F. N. Alyea, C. A. Cardelino, A. J. Crawford, P. J. Fraser, and R. D. Rosen, The atmospheric lifetime experiment, 3: Lifetime methodology and application to 3 years of CFC13 data, J. Geophys. Res., 88, 8379-8400, 1983. Cunnold, D. M., R. G. Prinn, R. A. Rasmussen, P. G. Simmonds, F. N. Alyea, C. A. Cardelino, A. J. Crawford, P. J. Fraser, and R. D. Rosen, The atmospheric lifetime experiment, 4: Results for CF2C12 based on 3 years of data, J. Geophys. Res., 88, 8401-8414, 1983. Cunnold, D. M., R. G. Prinn, R. A. Rasmussen, P. G. Simmonds, F. N. Alyea, C. A. Cardelino, A. J. Crawford, P. J. Fraser, and R. D. Rosen, Atmospheric lifetime and annual release estimates for CFC13 and CF2C12 from 5 years of ALE data, J. Geophys. Res., 91, 10,797-10,817, 1986. Curtis, A. R., and P. W. Sweetenham, FACSIMILE/CHECKMAT Report R12805, Harwell Laboratory, Oxfordshire, England,
User's 1987.
Dagaut, P., T. J. Wallington, and M. J. Kurylo, Temperature dependence constant for the HO2 + CH302 gas-phase reaction, J. Phys. Chem., 1988a. Dagaut, P., T. J. Wallington, and M. J. Kurylo, Flash photolysis spectroscopy study of the gas-phase reaction HO2 + C2H502 range 228-380 K, J. Phys. Chem., 92, 3836-3839, 1988b. Dagaut, P., T. J. Wallington, and M. J. Kurylo, A flash photolysis absorption spectrum and self-reaction kinetics of CH2CICH202 phase, Chem. Phys. Lett., 146, 589-595, 1988c. Dagaut, P., T. J. Wallington, and M. J. Kurylo, the self reactions of CH2C102 and CH2FO2 Kinet., 20, 815-826, 1988d.
Manual,
AERE
of the rate 92, 3833-3836,
kinetic absorption over the temperature
investigation of the UV radicals in the gas
The UV absorption spectra and kinetics radicals in the gas phase, Int. J. Chem.
Dahlem Conference, Report of the Dahlem Workshop on the nature of seawater, March 15, 1975, E. D. Goldberg, ed., Dahlem Conferenzen, Publisher, Berlin, 1976. Daikin,
DaiflonGas
technical
information,
Osaka,
Dale, O., The interaction of enflurane, halothane, trifluoroacetic acid with the binding of acidic Pharmacol., 35, 557-561, 1986.
R-8
Japan,
of
10-
1989.
and the halothane metabolite drugs to human serum albumin,
Biochem.
REFERENCES Dallmeier, E., and D. Henschler, Determination acid after inhalation of low concentrations Pharmacol., 297, R20, 1977.
and pharmacokinetics of trifluoroacetic of halothane, Naunyn-Schmiedebergs Arch.
Dallmeier, E., and D. Henschler, Halothan-Belastung am arbeitsplatz Deutsche Medizinische Wochenschrift, 106, 324-328, 1981. Danckwerts, Davidson,
P. V., Gas-Liquid J. A., H. I. Schiff,
Reactions, T. J. Brown,
276 pp.,
McGraw-Hill,
and C. J. Howard,
of the rate constants for reactions of O(1D) atoms Chem. Phys., 69, 4277-4279, 1978.
im operationssaal,
1970.
Temperature
with a number
dependence
of halocarbons,
Davis, D. D., G. Machado, B. Conaway, Y. Oh, and R. T. Watson, A temperature dependent kinetics study of the reaction of OH with CH3CI, CH2C12, CHC13, CH3Br, J. Chem. Phys., 65, 1268-1274, 1976.
J.
and
Davis, D. D., J. D. Bradshaw, M. O. Rogers, S. T. Sandholm, and S. Kesheng, Free tropospheric and boundary layer measurements of NO over the central and eastern north pacific ocean, J. Geophys. Res, 92, D2, 2049-2070, 1987. Davison, A. W., Uptake, transport and accumulation of soil and airborne fluorides by vegetation, Fluorides: Effects on Vegetation, Animals, and Humans, Ed. by Shupe, L., Peterson, H. B., and Leone, N. C., Paragon Press, Salt Lake City, UT, 61-82, 1983. DeAngelo, A. B., S. Herren-Freund, M. A. Pereira, Species sensitivity to the induction of peroxisome its metabolites, The Toxicologist, 6, 113, 1986. Dean,
J. A., ed., Lang "s Handbook
Delmas, Res.,
R. J., M. Briat, 87, 4314-4318,
of Chemistry,
and M. Legrand, 1982.
N. E. Shults, and J. E. Klaunig, proliferation by trichloroethylene
12th Edition,
Chemistry
of south
McGraw-Hill, polar
snow,
J.
and
1979. J. Geophys.
DeMore, W. B., M. J. Molina, S. P. Sander, D. M. Golden, R. F. Hampson, M. J. Kurylo, C. J. Howard, and A. R. Ravishankara, Chemical kinetics and photochemical data for use in stratospheric modeling, JPL Publication 87-41, Evaluation No. 8, Jet Propulsion Laboratory, Pasadena, CA, 196, 1987. Derwent, R. G., Two-dimensional model studies of the impact of aircraft emissions on tropospheric ozone, Atmos. Environ., 16, 1997-2007, Derwent, R. G., and A. E. J. Eggleton, Halocarbon distributions calculated with a two-dimensional 1270,
exhaust 1982.
lifetimes and concentration model, A tmos. Environ., 12, 1261-
1978.
Derwent, R. G., and A. R. Curtis, Two-dimensional model studies of some trace gases and free radicals in the troposphere, AERE Report R8853, H. M. Stationery Office, London,
1977.
Derwent, R. G., and A. Volz-Thomas, The tropospheric reactions with OH radicals, AFEAS Report, Section
R-9
lifetimes of halocarbons V, this report, 1989.
and their
REFERENCES Dewar, M. J. S., and H. S. Rzepa, Ground state of molecules. 53. MNDO calculations for molecules containing chlorine, J. Comput. Chem., 4, 158-169, 1983. Dilling, W. L., Interphase transfer processes. II. Evaporation rates of chloromethanes, ethanes, ethylenes, propanes, and propylenes from dilute aqueous solutions. Comparisons with theoretical predictions, Env. Sci. Technol., 11,405-409, 1977. Dimitriates, B., and M. Dodge, ed., Proceedings of the empirical approach (EKMA ) validation workshop, EPA-600/9-83-014, Agency, Research Triangle Park, N.C., August, 1983. Dob6 S., T. Berces, and F. Marta, Gas phase decomposition pentoxy radicals, Int. J. Chem. Kin., 18, 329, 1986.
kinetic modeling U.S. Environ. Prot.
and isomerization
of 2-
Dodge M., Combines use of modeling techniques and smog chamber data to derive ozoneprecursor relationships, Proceedings of the International Conf. of Photochemical Oxidant Pollution and its Control, I1, EPA-600/3-77.001b, 881-889, U.S. Environ. Prot. Agency, Research Triangle Park, N.C., 1977a. Dodge, M., Effect 600/3-77-048, 1977b.
of selected parameters on predictions of a photochemical U.S. Environ. Prot. Agency, Research Triangle Park,
model, EPTN.C., June
Dognon, A. M., F. Caralp, and R. Lesclaux, Reactions des radicaux chlorofluoromethyl peroxyles avec NO: Etude cinetique dans le domaine de temperature comris entre et 430 L, J. Chim. Phys., 82, 349-352, 1985. Doley, D., Experimental analysis of fluoride susceptibility of grape Foliar fluoride accumulation in relation to ambient concentration Phytol, 96, 337-351, 1984. Donahue, T. M., R. J. Cicerone, hydrogen on ozone depletion 1976.
S. C. Liu, and W. L. Chameides, on chlorine reactions, Geophys.
Donovan, R. J., K. Kaufmann, and J. Wolfrum, Reactions chlorofluoromethanes and CC14, Nature, 262,204-205, Downing, R. C., Fluorocarbon NJ, 1988.
Refrigerants
Duce, R. A., On the source of gaseous Res., 74, 4597-4599, 1969.
Handbook,
chlorine
in the marine
Duce, R. A., and E. J. Hoffman, Chemical fractionation Earth and Planet. Sci., 4, 187-228, 1976.
vine (Vitis vinefera L.): and windspeed, New
Effect of odd Res. Lett., 3, 105-108,
of O(1D) 1976. Prentice
with
Hall,
Englewood
atmosphere,
at the air/sea
Cliffs,
J. Geophys.
interface,
Ann.
Duce, R. A., J. W. Winchester, and T. Van Nahl, Iodine, bromine and chlorine Hawaiian marine atmosphere, J. Geophys. Res., 70, 1775-1799, 1965.
in the
Duce, R. A., W. H. Zoller, and J. L. Moyers, Antarctic atmosphere, J. Geophys. Res.,
in the
Particulate and gaseous 78, 7802-7811, 1973.
R-10
230
halogens
Rev.
REFERENCES Dunnold, D., M., Fluorocarbon lifetime and releases from 5 years of ALE data, paper presented at CSIRO symposium, The Scientific Application of Baseline Observations of Atmospheric Composition, Aspendale, Australia, Nov. 7-9, 1984. DuPont, "Freon technical information" communication with C, A. McCain
data sheets and unpublished data, private and T. C. Berger, Wilmington, DE, 1989.
Eberson, L., Studies on the Kolbe electrolytic synthesis IV. A theoretical investigation of the mechanism by standard potential calculations, Acta. Chem. Scand., 17, 2004-2018, 1963. Eberson, L., Electron-transfer reactions in organic chemistry, Advances in Physical Organic Chemistry, 18, V. Gold and D. Bethell, eds., Academic Press, New York, 185, 1982.
79-
Edney, E. O., J. W. Spence, and P. L. Hanst, Peroxy nitrate air pollutants: Synthesis and thermal stability, Nitrogenous Air Pollutants, D. Grosjean, ed., 111-135, Ann Arbor Science, Mich., 1979. Edney, E. O., J. W. Spence, and P. L. Hanst, Synthesis and thermal alkyl nitrates, J. Air Pollut. Control Assoc., 29, 741-763, 1979.
stability
Ehhah,
1974.
D. H., The
atmospheric
cycle
of methane,
Tellus,
26, 58-70,
Ehhah, D. H., How has the atmospheric concentration of CH4 changed?, Atmosphere, Physical, Chemical, and Earth Science Research Report Interscience, Chichester, England, 25-32, 1988.
of peroxy
The Changing 7, Wiley-
Elcombe, C. R., M. S. Rose, and I. S. Pratt, Biochemical, histological, and ultrastructural changes in rat and mouse liver following the administration of trichloroethylene, Toxicol. Appl. Pharmacol., 79, 365-376, 1985. Ellenrieder, W., and M. Reinhard, transformations of halogenated 331-344, 1988.
ATHIAS -- an information hydrocarbons in aqueous
Erchel,
Elsevier,
E., World
Water
Balance,
system for abiotic solutions, Chemosphere,
17,
1975.
Erickson, III, D. J., and R. A. Duce, On the global Geophys. Res., 93, 14,079-14,088, 1988.
flux of atmospheric
sea salt, J.
Eriksson, E., The yearly circulation of chloride geochemical and pedological implications,
and sulfur in nature: 1, Tellus, 11,373-403,
meteorological, 1959.
Eriksson, E., The yearly circulation of chloride geochemical and pedological implications,
and sulfur in nature: meteorological, 2, Tellus, 12, 63-109, 1960.
Ernst, J., H. Gg. Wagner, and R. Zellner, A combined flash photolysis/shock-tube study of the absolute rate constants for reactions of the hydroxyl radical with CH4 and CF3H around 1300 K, Ber. Bunsenges. Phys. Chem., 82,409-414, 1978.
R-11
REFERENCES Farmer, C. B., O. F. Raper, and R. H. Norton, Spectroscopic distribution of HC1 in the troposphere and stratosphere, 1976. Faust, S. D., and O. M. Aly, Chemistry Arbor, 1981. Finlayson-Pitts, experimental
of Natural
Waters,
B. J., and J. N. Pitts, Jr., Atmospheric techniques, Wiley, New York, 1986.
Fiserova-Bergerova, Environ, Health
detection Geophys.
Ann Arbor
Chemistry:
and vertical Res. Lett., 3, 13-16,
Science,
Ann
Fundamentals
V., Metabolism and toxicity of 2,2,2-trifluoroethyl Perspect., 21,225-230, 1977.
and
vinyl ether,
Fisher, D. A., C. H. Hales, D. L. Filkin, M. K. W. Ko, N. D. Sze, P. S. Connell, D. J. Wuebbles, I. S. A. Isaksen, and F. Strodal, Relative effects on stratospheric ozone of halogenated methanes and ethanes of social and industrial interest, AFEAS Report, Section VIII, this report, 1989a. Fisher, D. A., C. H. Hales, W.-C. Wang, M. K. W. Ko, and N. D. Sze, Relative on global warming of halogenated methanes and ethanes of social and industrial interest, AFEAS Report, Section IX, this report, 1989b. Fletcher, I. S. and D. Husain, Absolute reaction parafins by atomic absorption spectroscopy Chem., 80, 1837-1840, 1976. Fltihler, H., Polomski, J., and P. Blaser, Environ Qual., 11,461-468, 1982.
rates of oxygen in the vaccuum
Retention
Force, A. P., and J. R. Wiesenfeld, Collisional Direct determination of reaction efficiency, Fraser, J., and L. S. Kaminsky, Metabolism to toxicity, Toxicol. Appl. Pharmacol.,
(1D) with halogenated ultraviolet, J. Phys.
and movement
of fluoride
in soils, J.
deactivation of O(1D) by the halomethanes. J. Phys. Chem., 85, 782-785, 1981.
of 2,2,2-trifluoroethanol 89, 202-210, 1987.
Fraser, J., and L. S. Kaminsky, 2,2,2-Trifluoroethanol intestinal toxicity: the role of its metabolism to 2,2,2-Trifluoroacetaldehyde acid, Toxicol. Appl. Pharmacol., 94, 84-92, 1988.
and its relationship
and bone marrow and trifluoroacetic
Galloway, J. N., G. E. Likens, W. C. Keene, and J. M. Miller, The composition precipitation in remote areas of the world, J. Geophys. Res., 87, 8771-8786, Gehring,
D. G., Private
communication,
Gerkens, R., and J. A. Franklin, preparation, 1989. Gibbs, R. J., Mechanisms 1970.
E. I. DuPont
Hydrolysis
controlling
world
de Nemours,
of 1,1,1-trichloroethane,
water
chemistry,
Science,
Inc.,
of 1982.
1987.
manuscript
170,
in
1088-1090,
Gillespie, H. M., and R. J. Donovan, Reaction of O(1D) atoms with chlorofluoromethanes: Formation of C10, Chem. Phys. Lett., 37, 468-470,
R-12
effects
1976.
REFERENCES Gillespie, H. M., J. Garraway, and R. J. Donovan, halomethanes, J. Photochem., 7, 29-40, 1977. Gillotay,
D., P. C. Simon,
and G. Brasseur,
Reaction
Planet.
of O(21D2)
Space
Sci., in press,
Giorgi, F. and W. L. Chameides, The rainout parameterization J. Geophys. Res., 90, 7872-7880, 1985. Goldman, P., The carbon-fluorine 1123-1130, 1969. Goldman, P., The enzymatic Chem., 240, 3434-3438,
bond in compounds
cleavage 1965.
Goldman, P., and G. W. A. Milne, mechanism of the defluorination 1966.
of biological
interest,
bondin
E., B. L. Hammond,
B. Sadri,
model,
Science,
fluoroacetate,
164,
J. Biol.
bond cleavage. II. Studies on the J. Biol. Chem., 241, 5557-5559,
Goldman, P., G. W. A. Milne, and D. B. Keister, Carbon-halogen bond Studies on bacterial halidohydrolases, J. Biol. Chem., 243,428-434, Goldstein,
1989.
in a photochemical
of the carbon-fluorine
Carbon-fluorine of fluoroacetate,
with
and Y.-P.
Hsia,
Theoretical
reactions of O(3p) atoms with a series of fluoroolefins, THEOCHEM, 105, 315-324, 1983.
J. Molecul.
Goodwin, R. D., and W. M. Haynes, Thermophysical properties 700 K at pressures to 70 MPa, National Bureau of Standards, S. Government Printing Office, Washington, DC, 1982.
cleavage. 1968.
study
III.
of the
Struct.,
of isobutane from 114 to Technical Note 1051, U.
Gossett, J. M., Measurement of Henry's law constants for C1 and C2 chlorinated hydrocarbons, Env. Sci. Technol., 21,202-208, 1987. Green, R. G., and R. P. Wayne, Relative rate constants for the reactions with fluorocarbons and N20, J. Photochem., 6, 371-374, 1976/77a. Green, R. G., and R. P. Wayne, Vaccuum methanes and ethanes, J. Photochem., Greenberg, J. P., and P. R. Zimmerman, continental, and marine atmospheres, Gregory, G. L., et al., Air chemistry 91, 8603-8612, 1986.
ultra-violet absorption 6, 375-377, 1976/77b. Nonmethane J. Geophys.
over the tropical
spectra
of O(1D)
of halogenated
hydrocarbons in remote tropical, Res., 89, 4767-4778, 1984. forest
of Guyana,
J. Geophys.
Guderian, R., Air Pollution: Phytotoxicity of acidic gases and its significance pollution control, Springer Verlag, Berlin, 127 pp., 1977. Gutman, D., N. Sanders, and J. E. Butler, Kinetics ethoxy radicals with oxygen, J. Phys. Chem., Hacket,
P. A., and D. Phillips,
J. Chem.
of the reactions of methoxy 86, 66-70, 1982.
Soc. Farad.
R-13
atoms
I, 68, 329,
1962.
in air
and
Res.
REFERENCES Hammitt, J. K., F. Camm, P. S. Connell, A. Bemazai, Future emission scenarios ozone, Nature, 330, 711-716, 1987. Hampson,
R. F., M. J. Kurylo,
HCFCs
and HCFs
W. E. Mooz, for chemicals
and S. P. Sander,
with OH and O(1D),
K. A. Wolf, D. J. Wuebbles, that may deplete stratospheric
Evaluated
AFEAS
Report,
rate constants Section
and
for selected
III, this report,
Handwerk, V., and R. Zellner, Kinetics of the reactions of OH radicals with some halocarbons (CHC1F2, CH2CIF, CH2C1CF3, CH3CC1F2, CH3CHF2) in the termperature range 260-370 K, Ber. Bunsenges. Phys. Chem., 82, 1161-1166,
1989.
1978.
Hansen, J., G. Russell, D. Rind, P. Stone, A. Lacis, S. Lebedeff, R. Ruedy, and L. Travis, Efficient 3-D global models for climate studies: Models I and II, Mon. Weather Rev., 111, 609-662, 1983. H_u'ris, S. J., and J. A. Kerr, A kinetic and mechanistic nitrates in the photooxidation of n-heptane studied Chem. Kinet., 21,207-218, 1989.
study of the formation of alkyl under atmospheric conditions, Int. J.
Hart, E. J., S. Gordon, and J. K. Thomas, Rate constants for hydrated with organic compounds, J. Phys. Chem., 68, 1271-1274, 1964. Hartmann, J. Karth_iuser, by laser photofragment
and R. Zellner, Kinetics of the reactions CH302 emission, submitted to J. Phys. Chem, 1989.
Hartmann, J. Karth_iuser, J. P. Sawersyn, of the reaction C2H50 + 02 between 1989. Hautecloque. 1980.
electron
S., On the photooxidation
and R. Zellner, Kinetics 298 and 411 K, submitted
of gaseous
Hendry, D. G., and R. A. Kenley, Atmospheric EPA-560/12-79-O01, June, 1979.
products
+ HO2 studied
and HO2 product yield to J. Phys. Chem,
CHC13, J. Photochem.,
reaction
reactions
of organic
14, 157,
compounds,
Herren-Freund, S., M. Pereira, M. Khoury, and G. Olson, Biochemical, histological, ultrastructural changes in rat and mouse liver following the administration of trichloroethylene, Toxicol. Appl. P harmacol., 90, 183-189, 1987. Herron,
J. T., Private
communication,
and
1989.
Higashi, Y., M. Ashizawa, Y. Kabata, T. Majima, M. Uematsu, and K. Watanabe, Measurements of vapor pressure, vapor-liquid coexistence curve and critical parameters of refrigerant 152a, JSME Int. J., 30, 1106-1112, 1987. Hine, J., and D. C. Duffey, Methylene derivatives as intermediates in polar reactions. XV. The decomposition of dichlorofluoroacetic acid, J. Am. Chem. Soc., 81, 1129-1131, 1959a. Hine, J., and D. C. Duffey, Methylene derivatives XVI. The decomposition of chlorodifluoroacetic 1136, 1959b.
R-14
as intermediates in polar reactions. acid, J. Am. Chem. Soc., 81, 1131-
REFERENCES Hine, J., R. Wiesboeck, deuterium exchange 1219-1222, 1961.
and R. G. Ghirardelli, The kinetics of 2,2-dihalo-1,1,1-trifluoroethanes,
of the base-catalyzed J. Am. Chem. Soc.,
83,
Hitchcock, D. R., L. L. Spiller, and W. E. Wilson, Sulfuric acid aerosols and HC1 release in coastal atmospheres: Evidence of rapid formation of sulfuric acid particulates, Atmos. Environ., 14, 165-182, 1980. HMSO, Chlorofluorocarbons and their effect on stratospheric Department of the Environment, H.M. Stationery Office,
ozone, Pollution London, 1976.
Hogo, H., and M. W. Gery, User's guide for executing OZIPM-4 optional mechanisms, Volume I, EPA Report No. 600/8-88/073, Park, N.C., 1988.
Paper
5,
with CPM-IV or Research Triangle
Hohorst, F. A., and D. D. DesMarteau, Some reactions of CF3OO derivatives with inorganic compounds. Synthesis and vibrational spectrum of trifluoromethyl peroxynitrate, lnorg. Chem., 13,715-719, 1974. Holaday, D. A., and R. Cummah, Bergerova, 1977.
Personal
communication,
Holaday, D. A., and R. Cummah, Annual Meeting, Anesthesiologists, San Francisco, 1976.
reported
American
in Fiserova-
Society
of
Holdren, M. W., C. W. Spicer, and J. M. Hales, Peroxyacetyl nitrate solubility and decomposition rate in acidic water, Atmos. Environ., 18, 1171-1173, 1984. Hong, H., and D. R. Kester, Oceanogr., 31,512-524,
Redox 1986.
state of iron in the offshore
Horiuchi, N., C-F bond rupture of monofluoroacetate bacteria and the enzyme, Seikagaku, 34, 92-98, Howard, C. J., and K. M. Evenson, fluorine, chlorine, and bromine 197-202, 1976a.
waters
by soil microbes. 1962.
of Peru,
Limnol.
Properties
of the
Rate constants for the reactions of OH with CI-I4 and substituted methanes at 296 K, J. Chem. Phys., 64,
Howard, C. J., and K. M. Evenson, Rate constants for the reactions of OH with ethane and some halogen substituted ethanes at 296 K, J. Chem. Phys., 64, 4303-4306, 1976b. Hubrich, C., and F. Stuhl, ethanes of atmospheric
The ultraviolet absorption interest, J. Photochem.,
Hudson, R. F., and G. E. Moss, The mechanism Acetyl chloride, J. Chem. Soc., 5157-5163,
of some halogenated 12, 93-107, 1980.
of hydrolysis 1962.
of acid chlorides.
Huie, R. E., and P. Neta, Chemical behavior of SO3- and SO5" radicals solutions, J. Phys. Chem., 88, 5665-5669, 1984.
R-15
methanes
in aqueous
and
Part IX.
REFERENCES Huie, R. E., D. Brault, and P. Neta, Rate constants for one-electron CF302 o, CC1302 °, and CBr302 • radicals in aqueous solutions, Interactions, 62,227-235, 1987.
oxidation by the Chem. Biol.
Hurst, D. F., and F. S. Rowland, Seasonal variations in the latitudinal tropospheric carbon monoxide: 1986-1988, EOS, 70, 288, 1989. Hutton, J. T., Chloride 208, 1976.
in rainwater
in relation
to distance
from the ocean,
Huybrechts, G., and L. Meyers, Gas-phase chlorine-photosensitized wichloroethylene, Trans. Faraday Soc., 62,2191-2204, 1966. Huybrechts, G., G. Martens, Soc., 61, 1921, 1965.
L. Meyers,
J. Olbregts,
distribution
Search,
oxidation
and K. Thomas,Trans.
of
7, 207-
of
Faraday
Huybrechts, G., J. Olbregts, and K. Thomas, Gas-phase chlorine-photosensitized oxidation and oxygen-inhibited photochlorination of tetrachloroethylene and pentachloroethylene, Trans. Faraday Soc., 63, 1647-1655, 1967. Irmann, R. B., A simple correlation between water solubility hydrocarbons and halohydrocarbons, Chem. Ing. Tech., Ishii, D. N., and A. N. Corbascio, Some metabolic effects tissue culture cells in vitro, Anesthesiology, 427-438,
and structure 37, 789-798,
of halothane 1971.
of 1965.
on mammalian
Jacob, D. J., Chemistry of OH in remote clouds and its role in the production acid and peroxymonosulfate, J. Geophys. Res., 91, 9807-9826, 1986.
of formic
Jacob, D. J., and S. C. Wofsy, Photochemical production of carboxylic acids in a remote continental atmosphere, Acid Deposition Processes at High Elevation Sites,, M. H. Unsworth and D. Fowler, eds., D. Reidel, Hingham, MA, in press, 1989. Jacobsen, J. S., L. I. Heller, northeaster conurbation, JANAF
Thermochemical
and P. van Leuken, Acidic precipitation at a site within Water Air Soil Pollut., 6, 339-349, 1976. Tables,
2nd Ed., Stull,
R., and H. Prophet,
Japanese Association of Refrigeration, Thermophysical chlorodifluoromethane R22, JAR,, Tokyo, 1975.
properties
eds.,
the
1979.
of refrigerants,
Jayanty, R. K. M., R. Simonaitis, and J. Heicklen, The phytolysis of chlorofluoromethanes in the presence of 02 or 03 at 213.9 nm and their reactions O(1D), J. Photochem., 4, 382-398, 1975. Jenkin, M. E., R. A. Cox, G. D. Hayman, and L. J. Whyte, Kinetic CH302 + CH302 and CH302 + HO2 using molecular modulation Chem Soc., Faraday Trans. 2, 84,913-930, 1988.
study of the reactions spectrometry, J.
Jeong, K.-M., and F. Kaufman, Rates of the reactions of 1,1,1-trichloroethane (methyl chloroform) and 1,1,2-trichloroethane with OH, Geophys. Res. Lett, 6, 757-759, 1979.
R-16
with
REFERENCES Jeong, K.-M., and F. Kaufman, Kinetics of the reaction of hydroxyl and with nine C1- and F-substituted methanes. I. Experimental and applications, J. Phys. Chem., 86, 1808-1815, 1982a.
radical results,
with methane comparisons,
Jeong, K.-M., and F. Kaufman, Kinetics of the reaction of hydroxyl radical with methane and with nine CI- and F-substituted methanes. 2. Calculation of rate parameters as a test of transition-state-theory, J. Phys. Chem., 86, 1816-1821, 1982b. Jeong, K.-M., K.-J. Hsu, J. B. Jeffries, and F. Kaufman, with C2H5, CH3CC13, CH2C1CHC12, CH2C1CC1F2, 88, 1222-1226, 1984. Johnson, J. E., The lifetime 938-940, 1981.
of carbonyl
Junge,
and radioactivity,
C. E., Air chemistry
sulfide
Kinetics of the reactions and CH2FCF3, J. Phys.
in the troposphere,
282pp.,
Academic
Geophys.
Press,
of OH Chem.,
Res. Lett,
8,
1963.
Junge, C. E., and R. T. Werby, The concentration of CI-, Na +, K+, Ca + and SO4 = in rain water over the U.S., J. Meteorol., 15, 417-425, 1958. Kabata, Y., S. Tanikawa, M. Uematsu, and K. Watanabe, Preprint, tenth thermophysical properties, Gaithersburg, MD, Int. J. Thermophysics, published, 1989. Kagann, R. H., J. W. Elkins, and R. L. Sams, Absolute 11 and F-12 in the 8- to 16-I.tm region, J. Geophys. Kanome, Y., and I. Fujita, University, Yokahama, Kelly, M., Isolation 208, 809-810,
B.S. Thesis, Department Japan, 1986.
of bacteria 1965.
able to metabolize
band Res.,
of Mechanical
fluoroacetate
The atmospheric 1984.
Khalil, M. A. K., and R. A. Rasmussen, Nature, 292,823-824, 1981.
Increase
of CHC1F2
Engineering,
for eulerian Report DW
Nature,
acid 930237,
of methylchloroform
atmospheric methane: Atmos. Environ., 19, 397-
in the earth's
atmosphere,
Khalil, M. A. K., and R. A. Rasmussen, Trichlorotrifluoroethane (F-113) trends at Pt. Barrow, Alaska, Geophysical Monitoring for Climate Change, No. 13, Summary Report 1984, U.S. Department of Commerce, ERL/NOAA, Boulder, CO, 1985. Kinnison, oxide
D., H. Johnston, and D. J. Wuebbles, Ozone calculations with large and chlorine changes, J. Geophys. Res., 93, 14,165-14,175, 1988.
R-17
F-
Keio
of fluoroacetamide,
lifetime
Khalil, M. A. K., and R. A. Rasmussen, Causes of increasing Depletion of hydroxyl radicals and the rise of emissions, 407, 1985.
on
strengths of halocarbons 88, 1427-1432, 1983.
Kerr, J. A., and J. G. Calvert, Chemical transformation modules deposition models, vol. I: The gas-phase chemistry, NCAR Dec., 1984. Khalil, M. A. K., and R. A. Rasmussen, (CH3CC13), Tellus, 36B, 317-332,
symposium 10, to be
nitrous
REFERENCES Kirsch, L. J. and D. A. Parkes, Recombination of tertiary butyl peroxy radicals. Part 1. Product yields between 298 and 373 K, J. Chem. Soc., Faraday Trans. 1, 77, 293307, 1981. Kirsch, L. J. D. A. Parkes, T. J. Wallington, and A. Woolley, isopropylperoxy radicals in the gas phase, J. Chem. Soc., 2300, 1978. Klaasen, C., M. Amdur, and J. Doull Publishing Company, 13, 1986. Kletskii,
A. V., Inz.-Fiz.
(eds), Casarett
Zh., (in Russian
only),
Self-reactions of Faraday Trans. 1, 74, 2293-
and Doull's
7(4),
40-43,
Toxicology,
MacMillan
1964.
Ko, M. K. W., K. K. Tung, D. K. Weisenstein, and N. D. Sze, A zonal-mean model stratospheric tracer transport in isentropic coordinates: numerical simulations for nitrous oxide and nitric acid, J. Geophys. Res., 90, 2313-2329, 1985.
of
Ko, M. K. W., N. D. Sze, M. Livshits, M. B. McElroy, and J. A. Pyle, The seasonal latitudinal behavior of trace gases and 03 as simulated by a two-dimensional model the atmosphere, J. Atmos. Sci., 41, 2381-2408, 1984.
and of
Kohlen, R., H. Kratzke, and S. Mueller, Thermodynamic compressed liquid difluorochloromethane, J. Chem. 1985.
properties of saturated and Thermodynamics, 17, 1141-1151,
Kormann, C., D. W. Bahnemann, and M. R. Hoffman, Environmental iron oxide an active photocatalyst? A comparative study of Fe203, Photochem. Photobiol. A: Chem., in press, 1989. Kostyniak, P., H. B. Bosmann, and F. A. Smith, Defluorination by rat liver subcellular fractions, Toxicol. Appl. Pharmacol.,
photochemistry: is ZnO, and TiO2, J.
of fluoroacetate in vitro 44, 89-97, 1978.
Koubek, E., M. L. Haggett, C. J. Battaghlia, K. M. Ibne-Rasa, H. Y. Pyun, and J. O. Edwards, Kinetics and mechanism of the spontaneous decompositions of some peroxoacids, hydrogen peroxide, and t-butyl hydroperoxide, J. Am. Chem. Soc., 85, 2263-2268, 1963. Kritz, M. A,. and J. Rancher, atmosphere, J. Geophys.
Circulation of Na, C1 and Br in the tropical Res., 85, 1633-1639, 1980.
Kubota, H., Y. Tanaka, T. Makita, H. Kashiwagi, properties of 1-chloro-l,2,2,2-tetrafluoroethane 101, 1988.
marine
and M. Noguchi, Thermodynamic (R124), Int. J. Thermophsyics,
9, 85-
Kurylo, M. J., P. C. Anderson, and O. Klais, A flash photolysis resonance fluorescence investigation of the reaction OH + CH3CCI3 -> H20 + CH2CC13, Geophys. Res. Lett., 6, 760-762, 1979. Kurylo, M. J., P. Dagaut, T. J. Wallington, and D. M. Neuman, Kinetic measurements of the gas-phase HO2 + CH302 cross-disproportionation reaction at 298 K, Chem. Phys. Lett., 139, 513-518, 1987.
R-18
REFERENCES Lacis, A., J. Hansen, P. Lee, T. Mitchell, and S. Lebedeff, gases, 1970-1980, Geophys. Res. Lett., 8, 1035-1038, Lal, M., C. Schoneich, J. Monig, halogenated organic radicals,
Greenhouse 1981.
and K. D. Asmus, Rate constants Int. J. Radiat. Biol., 54, 773-785,
Lamb, B., A. Guenther, D. Gay, and H. Westberg, A national hydrocarbon emissions, Atmos. Environ., 21, 1695-1705, Landing, W. M., and S. Westerlund, The solution Fjord, Mar. Chem., 23, 329-343, 1988.
chemistry
Latimer, W. M., The Oxidation States of the Elements Solutions, 2nd ed., pp. 45 & 128, Prentice-Hall, Lee, Y. N., Kinetics of some of Gas-Liquid Chemistry NY, 1984.
effect
of trace
for the reactions 1988.
inventory 1987.
of
of biogenic
of iron (II) in Framvaren
and Their Potentials New York, 1952.
in Aqueous
aqueous-phase reactions of peroxyacetylnitrate, Conference of Natural Waters, Brookhaven National Laboratory, Upton,
Lee,Y. N., G. I. Senum, and J. S. Gaffney, Peroxyacetylnitrate stability, solubility, and reactivity: implications for tropospheric nitrogen cycles and precipitation chemistry, Fifth International Conference of the Commission on Atmospheric Chemistry and Global Pollution, Oxford, England, 1983. Legrand, M., and R. J. Delmas, The ionic balance of Antarctic record, Atmos. Envrion., 18, 1867-1874, 1984. Legrand, M., and R. J. Delmas, Glaciol., 7, 20-25, 1985.
Spatial
variations
of snow
snow:
chemistry
Legrand, M., and R. J. Delmas, Formation of HCI in the Antarctic Geophys. Res., 93, 7153-7168, 1988. Leighton,
P. A., Photochemistry
Lenhardt, T. M., C. E. McDade, molecular oxygen, J. Chem.
of Air Pollution,
Academic
Press,
and K. D. Bayes, Rates of reaction Phys., 72,304-310, 1980.
A 10-year
in Adelie
atmosphere,
New
Land,
Ann.
J.
York,
of butyl
detailed
1961.
radicals
with
Lesclaux, R., A. M. Dognon, and F. Caralp, Photo-oxidation of halomethanes at low temperature: The decomposition rate of CC130 and CFC120 radicals, J. Photochem. Photobiol., A: Chemistry, 41, 1-11, 1987. Lesclaux, R., and F. Caralp, Determination of the rate constants for the reactions of CFCI202 radical with NO and NO2 by laser photolysis and time resolved mass spectrometry, Int. J. Chem. Kinet., 16, 1117-1128, 1984. Lesclaux, R., F. Caralp, A. M. Dognon, and D. Cariolle, The rate of formation of halomethyl peroxy nitrates in the stratosphere and their possible role as temporary reservoirs for C1Ox and NOx species, Geophys. Res. Lett., 13,933-936, 1986. Levy, H., Normal Science, 173,
atmosphere: Large 141-143, 1971.
radical
and formaldehyde
R-19
concentrations
predicted,
REFERENCES Lewis, R. S., S. P. Sander, S. Wagner, and R. T. Watson, Temperature-dependent constants for the reaction of ground-state chlorine with simple alkanes, J. Phys. Chem., 84, 2009-2015, 1980. Liebhafsky, H. A., and A. Mohammed, The kinetics hydrogen peroxide by iodide ion, J. Am. Chem.
rate
of the reduction, in acid solution, Soc., 55, 3977-3986, 1933.
Liebl, K. H., and W. Seiler, CO and H2 destruction at the soil surface, Proc. "Microbial Production and Utilisation of Gases", Goltze Druck, Gottingen, Republic of Germany, 1976.
Symp. Federal
Lightfoot, P. D., B. Veyret, and R. Lesclaux, A flash-photolysis study of the CH302 HO2 reaction between 248 and 573 K, J. Phys. Chem., 93, 1989. Lin, X., M. Trainer, and S. C. Liu, On the linearity of the tropospheric J. Geophys. Res., 93, D12, 15,879-15,888, 1988.
ozone
14 by cosmic
ray neutrons,
Review
+
production,
Lind, J. A., and G. L. Kok, Henry's law determinations for aqueous solutions of hydrogen peroxide, methylhydroperoxide, and peroxyacetic acid, J. Geophys. 91, 7889-7895, 1986. Lingenfelter, R. E., Production of carbon Geophysics, 1, 35-55, 1963.
of
Res.,
in
Liss, P. S., Gas transfer: Experiments and geochemical implications, Air-Sea Exchange of Gases and Particles, NATO ASI Series, 559 pp., P. S. Liss and W. G. N. Slinn, eds., Reidel Publishing Company, 1983. Liss,
P. S., and P. G. Slater, 194, 1974.
Flux of gases
across
the air-sea
interface,
Nature,
247,
181-
Liu, R., R. E. Huie, and M. J. Kurylo, Rate constants for the reactions of the OH radical with some hydrochlorofluorocarbons over the temperature range 270 to 400k, submitted to J. Phys. Chem., 1989. Liu,
S. C., M. Trainer, F. C. Fehsenfeld, D. D. Parrish, E. J. Williams, D. W. Fahey, G. Hubler, and P. C. Murphy, Ozone production in the rural troposphere and the implications for regional and global ozone distributions, J. Geophys. Res., 92, 4191, 1987.
Livingstone, D. A., Chemical Paper 440-G, 1963.
composition
of rivers
and lakes,
U.S. Geol.
Surv.
Profess.
Lloyd, S. C., D. M. Blackburn, and P. M. D. Foster, Trifluoroethanol and its oxidative metabolites: Comparison of in vivo and in vitro effects in rat testis, Fd. Chem. Toxic., 24, 653-654, 1986. Lloyd, S. C., D. M. Blackburn, and P. M. D. Foster, Trifluoroethanol and its oxidative metabolites: Comparison of in vivo and in vitro effects in rat testis, Toxicol. Appl. Pharmacol., 92, 390-401, 1988. Logan, J. A., Tropospheric influence, J. Geophys.
ozone: Seasonal behavior, Res., 90, 10,463-10,482,
R-20
trends, 1985.
and anthropogenic
REFERENCES Logan, J. A., M. J. Prather, S. C. Wofsy, and M. B. McElroy, Tropospheric A global perspective, J. Geophys. Res., 86, 7210-7254, 1981.
chemistry:
Lorenz, K., D. Riisa, R. Zellner, and B. Fritz, Laser photolysis-LIF kinetic studies of the reactions of CH30 and CH2CHO with 02 between 300 and 500 K, Ber. Bunsenges Phys. Chem., 89, 341-342, 1985. Louis, J. F., Mean meridional circulation. The natural stratosphere Monograph 1, Dept. of Trans., DOT-TST-75-51, 6-23 to 6-49, Lovelock, J. E., R. J. Maggs, and R. J. Wade, Atlantic, Nature, 241,194-196, 1973.
Halogenated
Lyman, W. J., Estimation of physical properties, Chemicals, I, W. B. Neely and G. E. Blau, 1985.
of 1974, ClAP 1975.
hydrocarbons
in and over
Environmental Exposure from eds., CRC Press, Boca Raton, FL,
Lyman, W. J., W. F. Reehl, and D. H. Rosenblatt, Handbook Estimation Methods, McGraw-Hill Book Company, New
of Chemical York, 1982.
F., Why the sea is salt, Scientific
American,
233,
104-115,
13-47,
Property
Mabey, W., and T. Mill, Critical review of hydrolysis of organic compounds environmental conditions, J. Phys. Chem. Ref. Data, 7, 383-483, 1978. Maclntyre,
under
1970.
Mackay, D., and W. Y. Shiu, A critical review of Henry's law constants for chemicals environmental interest, J. Phys. Chem. Ref. Data, 10, 1175-1199, 1981. MacLean, suture
D. C., L. H. Weistein, D. C. McCune, red spot in "Elberta' peach", Environ.
Madhavan, V., H. Levanon, 76, 15-22, 1978.
and P. Neta,
the
of
and R. E. Schneider, Fluoride-induced Exp. Bot., 24, 353-367, 1984.
Decarboxylation
by SO4-radicals,
Radiat.
Res.,
Maenhaut, W., W. H. Zoller, R. A. Duce, and G. L. Hoffmann, Concentration and size distribution of particular trace elements in the South Polar atmosphere. J. Geophys. Res., 84, 2021-2031, 1979. Magid,
H., Allied
Signal
Corporation,
Mahadevan, T. N., V. Meenakashy, precipitation, Atmos. Environ.,
Private
communication,
and U. C. Mishra, Fluoride 20, 1745-1749, 1986.
1988. cycling
in nature
through
Makide, Y., and F. S. Rowland, Tropospheric concentrations of methyl chloroform, CH3CCI3, in January 1978 and estimates of atmospheric residence times for hydrohalocarbons, Proc. Nat'l Acad. Sci.(USA ), 78, 5933-5937, 1981. Marais, J. S. C., monofluoroacetic acid, the toxic principle of "Gifblaar" Dichapetalum cymosum (Hook), Engl. Onderstepoort J. Vet Sci. Animal Ind, 20, 67-73, 1944. Mario, M., K. Fiyu, R. Takiyama, F. Chikasue, H. Kikuchi, and L. Ribaric, Quantitative analysis of trifluoroacetate in the urine and blood by isotachophoresis, Anesthesiology, 53, 56-59, 1980.
R-21
REFERENCES Martens, C. S., J. J. Wesolowski, R. C. Harriss, and R. Kaifer, Chlorine Rican and San Francisco Bay area marine aerosols, J. Geophys. Res, 1973.
loss for Puerto 78, 8778-8792,
Martens, G. J., M. Godfroid, J. Delvaux, and J. Verbeyst, Gas phase hydrogen abstraction from asymmetrically halogenated ethanes by chlorine atoms, Int. J. Chem. Kin., 8, 153, 1976. Martin, J.-P., and G. Paraskevopoulos, A kinetic study of the reactions of OH radicals with fluoroethanes. Estimates of C-H bond strengths in fluoroalkanes, Can. J. Chem., 61,861-865, 1983. Mathias, E., E. Sanhueza, I. C. Hisatsune, and J. Heicklen, oxidation and the ozonolysis of C2C14, Can. J. Chem.,
The chlorine atom sensitized 52, 3852-3862, 1974.
McAdam, K., B. Veyret, and R. Lesclaux, UV absorption spectra of HO2 and CH302 radicals and the kinetics of their mutual reactions at 298 K, Chem. Phys. Lett, 133, 3944, 1987. McAdam, C2H4
K. G., and R. W. Walker, Arrhenius parameters for the reaction C2H 5 + 02 -> + HO2, J. Chem. Soc., Faraday Trans. 2, 83, 1509-1517, 1987.
McCaulley, CH30 McClenahen, Environ.
J. A., S. Anderson, J. B. Jeffries, with NO2, Chem. Phys. Lett, 115, J. R., Distribution Qual., 5, 472-475,
and F. Kaufman, 180-186, 1985.
of soil fluorides 1976.
McCune, D. C., On the establishment of air quality atmospheric fluorine on vegetation, Air Quality Institute, New York, 33 pp., 1969.
Kinetics
near an airborne
of the reaction
fluoride
source,
J.
criteria, with reference to the effects of Monograph 69-3, American Petroleum
McCune, D. C., D. H. Silberman, and L. H. Weinstein, Effects of relative humidity and free water on the phytotoxicity of hydrogen fluoride and cryolite, Pro¢. Int. Clean Air Congr., 4th, Tokyo, 16-20 May 1977, Japanese Union of Air Pollution Prevention Associations, Tokyo, 116-119, 1977. McFarland, M., D. Kley, J. W. Drummond, A. L. Schmehekopf, and R. H. Winkler, Nitric oxide measurements in the equatorial Pacific region, Geophys. Res. Lett., 6, 605-608, 1979. McKay, C., M. Pandow, and R. Wolfgang, Geophys. Res., 68, 3829-3931, 1963.
On the chemistry
of natural
radiocarbon,
J.
McLinden, M. O., Physical properties of alternatives to the fully halogenated chlorofluorocarbons, AFEAS Report, Section II, this report, 1989. McLinden, M. O., J. S. Gallagher, L. A. Weber, G. Morrison, D. Ward, A. R. H. Goodwin, M. R. Moldover, J. W. Schmidt, H. B. Chae, T. J. Bruno, J. F. Ely, and M. L. Huber, Measurement and formulation of thermodynamic properties of refrigerants 134 ( 1,1,1,2-tetrafluoroethane) and 123 ( 1,1 -dichloro-2,2,2trifluoroethane), ASHRAE Trans. 95, to be published, 1989.
R-22
of
REFERENCES McMillen, Phys.
D. F., and D. M. Golden, Hydrocarbon Chem., 33, 493-532, 1982.
Mears, W. H., R. F. Stahl, McCann, Thermodynamic Chem., 47, 1449-1454,
S. R. Orfeo, properties 1955.
bond
dissociation
Ann.
Rev.
R. C. Shair, L. F. Kells, W. Thompson, and H. of halogenated ethanes and ethylenes, Ind. Eng.
Midgley, P. M., The production and release to the atmosphere (methyl chloroform), Atmos. Env., 23, No. 12, 1989. Miller, C., D. L. Filkin, A. J. Owens, model of stratospheric chemistry
energies,
of 1,1,1-trichloroethane
J. M Steed, and J. P. Jesson, A two-dimensional and transport, J. Geophys. Res., 86, 12,039, 1981.
Miller, C., J. M. Steed, D. L. Filkin, and J. P. Jesson, The fluorocarbon ozone theory, one-dimensional modeling, an assessment of anthropogenic perturbations, Atmos. Environ., 15, 729, 1981a. Moffett, J. W., and R. G. Zika, Reaction iron in seawater, Env. Sci. Technol.,
kinetics of hydrogen peroxide 21,804-810, 1987a.
with copper
7,
and
Moffett, J. W., and R. G. Zika, Photochemistry of copper complexes in seawater, Photochemistry of Environmental Aquatic Systems, ACS Symposium Series No. 327, R. G. Zika and W. J. Cooper, eds., Chapter 9, 116-330, 1987b. Mohammed, A., and H. A. Liebhafsky, The kinetics of the reduction by the halides, J. Am. Chem. Soc., 56, 1680-1685, 1934. Molina, M. J., and F. S. Rowland, Stratospheric atom-catalyzed destruction of ozone, Nature,
sink for chlorofluorocarbons. 249, 810-812, 1974.
Molina, M. J., and G. Arguello, Ultraviolet absorption vapor, Geophys. Res. Lett., 6, 953, 1979. Molina,
M. J., and L. T. Molina,
Work
of hydrogen
in progress,
spectrum
peroxide
Chlorine
of methylhydroperoxide
1990.
Monig, J., D. Bahnemann, and K. D. Asmus, One electron reduction of CC14 in oxygenated aqueous solutions: A CC1302-free radical mediated formation of C1- and CO2, Chem. Biol. Interactions, 45, 15-27, 1983. Moortgat, G., B. Veyret, and R. Lesclaux, Absorption spectrum of the acetylperoxy radical, J. Phys. Chem., 93, 2362-2368, Moortgat, HO2,
G. K., B. Veyret, and R. Lesclaux, Rate constants J. Phys. Chem., 93, in press, 1989.
and kinetics 1989.
for the reaction
of reactions
CH3COO2
Moortgat, G. K., J. P. Burrows, W. Schneider, G. S. Tyndall, and R. A. Cox, A study of the HO2 + CH3CHO reaction in the photolysis of CH3CHO, and its consequences for atmospheric chemistry, Proc. 4th European Symposium on the Physico-Chemical Behavior of Atmospheric Pollutants, D. Riedel Publ. Co., Dordrecht, 271-281, 1987. Morel, O., R. Simonaitis, and J. Heicklen, Ultraviolet absorption CC1302NO2, CC12FO2NO2, and CH302NO2, Chem. Phys.
R-23
spectra of HO2NO2, Lett., 73, 38-42, 1980.
+
REFERENCES Morrison, G., unpublished data, National Gaithersburg, MD, 1989. Morrison, S. R., Electrochemistry Plenum, New York, 1980.
Institute
of Standards
at Semiconductor
and Technology,
and Oxidized
Metal
Electrodes,
Mi.iller,
K. L., and H. J. Schumacher,
Z. Phys.
Chem.,
B37,
365,
1937a.
MiJller,
K. L., and
Z. Phys.
Chem.,
B35,
455,
1937b.
H. J. Schumacher,
Murray, J.J. ed., Appropriate use of fluorides Organization, 1-129, 1986.
for human
NAS, Halocarbons: Effects on stratospheric Washington, DC, 1976.
ozone,
health,
National
World
Academy
Health
of Science,
NASA Panel for Data Evaluation, Chemical kinetics and photochemical data for use in stratospheric modeling, Evaluation Number 8, W. B. Demore, M. J. Molina, S. P. Sander, D. M. Golden, R. F. Hampson, M. J. Kurylo, C. J. Howard, and A. R. Ravishankara, JPL Publ. 87-41, Sept. 15, 1987. NASA/WMO, Atmospheric ozone 1985: assessment of our understanding of the processes controlling its present distribution and change, WMO Report No. 16, sponsored by WMO, NASA, NOAA, FAA, UNEP, CEC, and BMFT, Washington, DC, 1986. National Research Council, Biologic Effects of Atmospheric Pollutants: National Academy of Sciences, Washington, DC, 1971. National Research Council, Sciences, Washington,
Chlorine and Hydrogen DC, 1976.
Neely, W. B., Hydrolysis, Environmental G. E. Blau, eds., CRC Press, Boca
Chloride,
National
Exposure from Chemicals, Raton, FL, 157-173, 1985.
Neely, W. B., and J. H. Plonka, Estimation of time-averaged concentrations in the troposphere, Environ. Sci. Tech.,
Flourides,
Academy
of
I, W. B. Neely
hydroxyl radical 12, 317-321, 1978.
Nelson, L., J. J. Treacy, and H. W. Sidebottom, Oxidation of methylchloroform, 3rd European Symposium on the Physico-Chemical Behaviour of Atmospheric Pollutants, B. Versino and G. Angeletti, eds., D. Riedel Publ. Co., Dordrecht, 263, 1984. Newell, R. E., J. W. Kidson, G. Vincent, and G. J. Boer, tropical atmosphere and interactions with extratropical Cambridge, MA, 1972. Nicksic, S. W., J. Harkins, and P. K. Mueller, Some structure, Atmos. Environ., 1, 11-18, 1967.
Proc. 258-
The general circulation of the latitudes, Vol. 1, MIT Press,
analyses
for PAN
Niki, H., P. D. Maker, C. M. Savage, and L. P. Breitenbach, FTIR of haloalkyl peroxynitrates formed via ROO + NO2 -> ROONO2 CF2C1), Chem. Phys. Lett., 61, 100-104, 1979.
R-24
and
and studies
of its
spectroscopic study (R=CCI3, CFCI2, and
REFERENCES Niki,
H., P. D. Maker, C. M. Savage, and L. P. Breitenbach, An FTIR study of the C1atom-initiated oxidation of CH2C12 and CH3C1, Int. J. Chem. Kinet., 12, 1O01-1012, 1980a.
Niki, H., P. D. Maker, C. M. Savage, and L. P. Breitenbach, and mechanism for the reaction of C1 atom with formyl 12,915-920, 1980b.
FTIR studies of the kinetics chloride, Int. J. Chem. Kinet.,
Niki, H., P. D. Maker, C. M. Savage, and L. P. Breitenbach, FTIR spectroscopic observation of peroxyalkyl nitrates formed via ROO + NO2 -> ROONO2, Chem. Lett., 55, 289-292, 1978. Niki, H., P. D. Maker, C. M. Savage, and L. P. Breitenbach, studies of the self-reaction of CH302 radicals, J. Phys. Niki, H., P. D. Maker, C. M. Savage, and L. P. Breitenbach, studies of the self-reaction of C2H502 radicals, J. Phys. Niki, H., P. D. Maker, C. M. Savage, and mechanism for Cl-atom-initiated 588-591, 1985.
Fourier transform infrared Chem., 85, 877-881,1981. Fourier transform infrared Chem., 86, 3825-3829, 1982.
and L. P. Breitenbach, FTIR reactions of acetaldehyde,
Nip, W. S., D. L. Singleton, reactions. 5. Reactions 297 K, J. Phys. Chem.,
R. Overand, and G. Paraskevopoulos, with CH3 F, CH2F2, CHF3, CH3CH2F 83, 2440-2443, 1979.
Okabe,
of Small
H., Photochemistry
Molecules,
J.Wiley
Phys.
& Sons,
study of the kinetics J. Phys. Chem., 89,
Rates of OH radical and CH3CHF2 at
1978.
Orlando, J. J., J. B. Burkholder, and A. R. Ravishankara, Atmospheric chemistry of hydrofluoroethanes and hydrochlorofluoroethanes: II. UV absorption cross-sections, to be submitted to J. Geophys. Res., 1990. Owens, A. J., C. H. Hales, D. L. Filkin, C. Miller, J. M. Steed, and J. P. Jesson, A coupled one-dimensional radiative-convective, chemistry transport model of the atmosphere, J. Geophys. Res., 90, 2283-2311, 1985. Packer, J. E., R. L. Willson, D. Bahnemann, and K. D. Asmus, Electron transfer reactions of halogenated aliphatic peroxyl radicals: Measurement of absolute rate constants by pulse radiolysis, J. C. S. Perkin, Trans. H, 296-299, 1980. Paraskevopoulos, G., D. L. Singleton, and R. S. Irwin, Rates of OH radical reactions. 8. Reactions with CH2FC1, CHF2C1, CHFC12, CH3CF2CI, CH3C1, and C2H5C1 at 297 K, J. Phys. Chem., 85, 561-564, 1981. Parkes, D. A., The roles of alkylperoxy and alkoxy radicals in alkyl radical oxidation room temperature, 15th International Symp. Combustion, 1974, The Combustion Institute, Pittsburgh, PA, 795-805, 1975. Parmelee, 1953.
H. M., Water
solubility
of Freon
refrigerants,
Refrig.
Eng.,
Parungo, F. P., C. T. Nagamoto, J. Rosinski, and P. L. Haagenson, aerosols over the Pacific Ocean, J. Atmos. Chem., 4, 199-226,
R-25
at
61, 1341-1345,
A study 1986.
of marine
REFERENCES Pate,
C. T., B. J. Finlayson, and J. N. Pitts, Jr., A longpath of the reaction of methylperoxy free radicals with nitric 6554-6558, 1974.
Pattison, F. L. M., Fluoroacetates, Toxic Aliphatic Publishing Co., London, 12-81, 1959.
Fluorine
infrared spectroscopic study oxide, J. Am. Chem. Soc., 96,
Compounds,
Elsevier
Peirson, D. H., P. A. Cawse, and R. S. Cambray, Chemical uniformity of airborne particulate material, and a maritime effect, Nature, 251,675-679, 1974. Penkett, S. A., N. J. D. Prosser, R. A. Rasmussen, measurements of CF4 and other fluorocarbons Geophys. Res., 86, 5172-5178, 1981.
and M. A. K. Khalil, Atmospheric containing the CF3 grouping, J.
Perry, R. A., R. Atkinson, and J. N. Pitts, Jr., Rate constants for the reaction of OH radicals with CHFC12 and CH3C1 over the temperature range 298-423 K and with CH2C12 at 298 K, J. Chem. Phys., 64, 1618-1620, 1976. Peters, L. K., Gases and their precipitation scavenging in the marine atmosphere, Air-Sea Exhange of Gases and Particles, NATO ASI Series, 559 pp., P. S. Liss and W. G. N. Slinn, eds., Reidel Publishing Company, 1983. Peters,
R. A., Lethal
synthesis,
Proc.
Peters, R. A., R. J. Hall, P. F. V. Ward, toxic compounds containing fluorine J., 77, 17-23, 1960.
Royal
J. N. Jr., H. L. Sandoval,
of O(ID)
atoms
Plumb, I. C., and K. R. Ryan, Lett., 92,236-238, 1982.
Kinetics
143-170,
1952. of the Biochem
of the gas-phase reaction of CH3F + 12 energy in methyl and methylene fluorides, Int.
and R. Atkinson,
with fluorocarbons
B139,
and N. Sheppard, The chemical nature in the seeds of Dichapetalum toxicarium,
Pickard, J. M., and A. S. Rodgers, Kinetics CH2FI + HI: the C-H bond dissociation J. Chem. Kinet., 15, 569-577, 1983. Pitts,
Soc.,
and N20,
Relative Chem.
of the reaction
rate constants Phys.
Lett.,
of CF302
for the reaction
29, 31-34,
1974.
with NO, Chem.
Phys.
Plumb, I. C., K. R. Ryan, J. R. Steven, and M. F. R. Mulcahy, Kinetics of the reaction of C2H502 with NO at 295 K, Int. J. Chem. Kinet., 14, 183-194, 1982. Polomski,
organic
J., H. Fluhler,
matter,
iron,
Prather, M. J., Tropospheric hydrochlorofluorocarbons
and P. Blaser, and aluminum,
Fluoride-induced mobilization J. Environ. Qual., 11,452-456,
and leaching 1982.
hydroxyl concentrations and the lifetimes of (HCFCs), AFEAS Report, Section V, this report,
Prather, M .J., European sources Atmos. Chem., 6, 375-406,
of halocarbons 1988.
and nitrous
oxide:
update
of
1989.
1986, J.
Prather, M., M. McElroy, S. Wofsy, G. Russell, and D. Rind, Chemistry of the global troposphere: Fluorocarbons as tracers of air motion, J. Geophys. Res., 92, 65796613, 1987.
R-26
REFERENCES Preuss,
P. W. A. G. Lemmens,
compounds Thompson
and L. H. Weinstein,
in plants. I. Metabolism Inst., 24, 25-32, 1968.
Preuss, P. W., and L. H. Weinstein, Defluorination of fluoroacetate,
Studies
of 2-14C-fluoroacetate,
Studies of fluoro-organic C ontrib. Bo yce Thompson
on fluoro-organic Contrib.
Boyce
compounds in plants. II. Inst., 24, 151-156, 1969.
Prinn, R. G., How have the atmospheric concentrations of the halocarbons Changing Atmosphere, Physical, Chemical, and Earth Science Research Wiley-Interscience, Chichester, England, 33-48, 1988. Prinn, R.G., D. Cunnold, R. Rasmussen, P. Simmonds, F. Alyea, Fraser, and R. Rosen, Atmospheric trends in methyl chloroform for the hydroxyl radical, Science, 238, 946-950, 1987.
changed?, The Report 7,
A. Crawford, and the global
P. average
Prinn, R. G., P. G. Simmonds, R. A. Rasmussen, R. D. Rosen, F. N. Alyea, C. A. Cardelino, A. J. Crawford, D. M. Cunnold, P. J. Fraser, and J. E. Lovelock, The atmospheric lifetime experiment, 1. Introduction, instrumentation and overview, J. Geophys. Res., 88, 8353-8367, 1983. Prinn, R. G., R. A. Rasmussen, P. G. Simmonds, F. N. Alyea, D. M. Cunnold, B. C. Lane, C. A. Cardelino, and A. J. Crawford, The atmospheric lifetime experiments, 5, results for CH3CC13 based on three years of data, J. Geophys. Res., 88, 8415-8426, 1983. Pritchard, acetyl Raemdonck, tropical
H. O., and H. A. Skinner, The heats of hydrolysis chlorides, J. Chem. Soc., 272, 1950.
H., W. Maenhaut, and M. O. Andreae, Chemistry of marine aerosol and equatorial Pacific, J. Geophys. Res., 91, 8623-8636, 1986.
Raiswell, R. W., P. Brimblecombe, D. L. Dent, Chemistry, John Wiley & Sons, New York, Ramanathan, Science,
of the chloro-substituted
over
the
and P. S. Liss, Environmental 1980.
V., Greenhouse effect due to chlorofluorocarbons: 190, 50-52, 1975.
Climate
implications,
Ramanathan, V., L. Callis, R. Cess, J. Hansen, I. Isaksen, W. Kuhn, A. Lucas, F. Luther, J. Mahlman, R. Reck, and M. Schlesinger, Climate-chemical interactions and effects of changing atmospheric trace gases, Rev. Geophys., 25, 1441-1482, 1987. Rapson, W., M. Nazar, and V. K. Bursky, Mutagenicity chlorination of organic compounds, Bull. Environ. 1980.
produced by aqueous Contam. Toxicol., 24,590-596,
Rasmussen, R. A., and M. A. K. Khalil, Atmospheric halocarbons: Measurements and analyses of selected trace gases, Proceedings of the NATO Advanced Study Institute on Atmospheric Ozone: Its Variation and Human Influences,, Rep. FAA-EE-80-20, edited by A. C. Aikin, DOT, FAA, Washington, DC, 209-231, 1980. Rasmussen, R. A., and M. A. K. Khalil, Latitudinal distributions of trace above the boundary layer, Chemosphere, 11,227-235, 1982.
R-27
gases
in and
REFERENCES Rasmussen, R. A., M. A. K. Khalil, Antarctica, Science, 211,285-287, Ravishankara, Ann. Rev.
and R. W. Dalluge, 1981.
A. R., Kinetics of radical reactions Phys. Chem., 39, 367-394, 1988.
Atmospheric
in the atmospheric
trace
gases
oxidation
in
of CH4,
Ravishankara, A. R., F. L. Eisele, and P. H. Wine, Pulsed laser photolysis-longpath laser abosrption kinetics study of the reaction of methylperoxy radicals with NO2, J. Chem. Phys., 73, 3743-3749, 1980. Ravishankara, reaction
A. R., F. L. Eisele, N. M. Kreutter, of CH302 with NO, J. Chem. Phys.,
and P. H. Wine, Kinetics 74, 2267-2274, 1981.
of the
Rayez, J.-C., M.-T. Rayez, P. Halvick, B. Duguay, R. Lesclaux, and J. T. Dannenberg, A theoretical study of the decomposition of halogenated alkoxy radicals. I. Hydrogen and chlorine extrusions, Chem. Phys., 116, 203-213, 1987. Reddy, J. K., D. L. Azarnoff, proliferators form a novel
and C. E. Hignite, Hypolipidaemic hepatic peroxisome class of chemical carcinogens, Nature, 283,397-398, 1980.
Reid, R. C., J. M. Prausnitz, and B. E. Poling, The Properties fourth edition, McGraw-Hill Book Company, New York,
of Gases 1987.
and Liquids,
Reimer, A., and F. Zabel, Thermal stability of peroxynitrates, 9th Int. Symposium Kinetics, University of Bordeaux, Bordeaux, France, July 20-25, 1986. Richardson, W.H., Acidity, hydrogen bonding and complex formation, Functional Groups, S. Patai, ed., John Wiley & Sons, Chichester, 160, 1983. Ridley, B. A., M. A. Carroll, and G. L. Gregory, Measurements boundary layer and free troposphere over the Pacific ocean, 2025-2048, 1987.
Principles
of Organic
The Chemistry of Chapter 5, 129-
of nitric oxide in the J. Geophys. Res., 92, D2,
Robbins, R. C., R. D. Cadle, and D. L. Eckhardt, The conversion hydrogen chloride in the atmosphere, J. Meteorol., 16, 53-59, Roberts, J. D., and M. C. Caserio, Basic Benjamin, Inc., New York, 1965.
on Gas
of sodium 1959.
Chemistry,
chloride
to
W. A.
Robertson, R. E., K. M. Kosky, A. Annessa, J. N. Ong, J. M. W. Scott, and M. S. Blandamer, Kinetics of solvolysis in water of four secondary alkyl nitrates, Can. J. Chem., 60, 1780-1785, 1982. Robins, D. E., and R. S. Stolarski, Comparison of stratospheric ozone destruction fluorocarbons 11, 12, 21, and 22, Geosphys. Res. Lett., 3, 603-606, 1976. Rogers, J. D., and R. D. Stephens, Absolute infrared intensities for F-113 an assessment of their greenhouse warming potential relative to other chlorofluorocarbons, J. Geophys. Res., 93, 2423-2428, 1988.
R-28
by
and F-114
and
REFERENCES Rognerud, B., I. S. A. Isaksen, and F. Stordal, Model studies of stratospheric ozone depletion, Proc. Quadrennial Ozone Symposium, Univ. of Gottingen, Rep. of Germany, 1988. Rosenberg, P. H., and T. Wahlstrom, Hepatotoxicity of halothane metabolites in vivo and inhibition of fibroblast growth in vitro, Acta Pharmacol. Toxicol., 29, 9-19, 1971. Rosenberg, P. H., and T. Wahlstrom, Trifluoroacetic acid and some possible intermediate metabolites of halothane as haptens, Anesthesiology, 38, 224-227, 1973. Rosenberg, P. H., Decrease in reduced glutathione and NADPH and inhibition of glucose6-phosphate dehydrogenase activity caused by metabolites of fluroxene and halothane, Ann. Med. Exp. Biol. Fenniae, 49, 84-88, 1971. Rothenberger, G., J. Moser, M. Gratzel, trapping and recombination dynamics Soc., 107, 8054-8059, 1985.
N. Serpone, and D. K. Sharma, Charge carrier in small semiconductor particles, J. Am. Chem.
Rowland, R. S., and I. S. A. Isaksen, Introduction, Chemical, and Earth Science Research Report England, 1-4, 1988.
The Changing Atmosphere, Physical, 7, Wiley-Interscience, Chichester,
Rubin, T. R., B. H. Levendahl, and D. M. Yost, The heat capacity, vaporization, vapor pressure, and entropy of 1,1,1-trichloroethane, Soc., 66, 279-282, 1944.
heat of transition, J. Am. Chem.
Rudolph, J., and D. H. Ehhalt, Measurements of C2-C5 hydrocarbons Atlantic, J. Geophys. Res., 86, 11,959-11,964, 1981. Ruppert, city
over
the North
H., Geochemical investigations on atmospheric precipitation in a medium-sized (Gottingen F.R.G.), Water Air Soil Pollut., 4, 447-460, 1975.
Ryaboshapko, A. G., The atmospheric sulfur cycle, The Global Biogeochemical Cycle, M. V. Ivanov and B. R. Freney, eds., Wiley, New York, 203-296, Ryan, K. R., and I. C. Plumb, Kinetics of the reactions 295 K, J. Phys. Chem., 86, 4678-4683, 1982.
of CF3 with O(3p)
Sulfur 1983.
and 02
at
Ryan, K. R., and I. C. Plumb, Kinetics of the reactions of CC13 with O and 02 and of CC1302 with NO at 295 K, Int. J. Chem. Kinet., 16, 591-602, 1984. Salih, I. M., T. Soeylemez, difluorochloromethane,
and T. I. Balkas, Radiolysis Radiat. Res., 67, 235-243,
of aqueous 1976.
Sander, S. P., and R. T. Watson, Kinetics studies of the reactions NO2, and CH302 at 298 K, J. Phys. Chem., 84, 1664-1674,
solutions
of CH302 1980.
of
with NO,
Sanders, N., J. E. Butler, L. R. Pasternack, and J. R. McDonald, CH30(X2E) production from 266 nm photolysis of methyl nitrite and reaction with NO, Chem. Phys., 48, 203208, 1980. Sandoval, O(1D)
H. L., R. Atkinson, atoms
and J. N. Pitts,
with fluorocarbons,
Jr., Reactions
J. Photochem.,
R-29
of electronically
3, 325-327,
1974.
excited
REFERENCES Sanhueza, CHF3,
E., The chlorine J. Photochem.,
atoms photosensitized 7, 325, 1977.
Sanhueza, 1975a.
E., and J. Heicklen,
Oxidation
oxidation
of CHC13,
of chloroethylene,
J. Phys.
CHCIF2,
Chem,
and
79, 677-681,
Sanhueza, E., and J. Heicklen, The chlorine-atom initiated and Hg(3P1)-photosensitized oxidation of CH2C12, J. Photochem., 4, 17-26, 1975b. Sanhueza, Kinet,
E., and J. Heicklen, 7, 399-415, 1975c.
The oxidation
of CFCICFC1
Sanhueza, E., and J. Heicklen, Chlorine atom senstized chloromethane, J. Phys. Chem, 79, 7-11, 1975d. Sanhueza,
E., and J. Heicklen,
Sanhueza, E., I. C. Hisatsune, 76, 801-826, 1976.
Int. J. Chem. and J. Heicklen,
Schmidt,. J. W., unpublished data, National Gaithersburg, MD, 1988. Schumacher,
Kinet,
H. J., and H. Thtirauf,
Z. Phys.
oxidation
7, 589,
Oxidation
Institute
and CF2CC12,
of dichloromethane
and
1975e. of haloethylenes,
of Standards
Chem.,
Int. J. Chem.
A189,
Chem.
Rev.,
and Technology,
183,
1941.
Schwarz, H. A., and R. W. Dodson, Equilibrium between hydroxyl radicals and thallium(II) and the oxidation potential of OH(aq), J. Phys. Chem., 88, 3643-3647, 1984. Seila, R. L. and W. A. Lonneman, Paper of Air Pollution Control Association, Seiler,
W., The cycle
of atmospheric
Seiler, W., and R. Conrad, trace gases, especially John Wiley and Sons,
88-150.8, presented at the 81st Annual Dallas, TX, June 20-24, 1988.
CO, Tellus,
26, 116-135,
Meeting
1974.
Contribution of tropical ecosystems to the global budget of CH4, H2, CO, and N20, The Geophysiology of Amazonia, New York, 133-160, 1987.
Seiler, W., and U. Schmidt, New aspects of CO and H2 cycles in the atmosphere, Proc. Int. Conf. on the Structure, Composition, General Circulation in the Upper and Lower Atmospheres and Possible Anthropogenic Perturbations, IAMAP, Toronto, Canada, 192-222, 1974. Seinfeld,
J. H., Urban
air pollution:
Seppelt, K., Trifluoromethanol, 1977.
State
CF3OH,
of the science, Agnew.
Chem.
Sexton, K., and H. Westberg, Nonmethane HC composition atmospheres, Atmos. Environ., 18, 1125-1132, 1984.
R-30
Science,
243,
Int. Ed. Engl.,
of urban
745-752,
1989.
16, 322-323,
and rural
REFERENCES Sidhu, S. S., Fluoride deposition the vicinity of a phosphorus
through precipitation and leaf litter in a boreal plant, Sci. Total Environ., 23,205-214, 1982.
Siever, R., The steady state of the earth's American, 230, 72-79, 1974.
crust,
Siggia, S., and J. G. Hanna, Quantitative Wiley & Sons, New York, 325-372,
Organic 1979.
Sillen,
L. G., The ocean
as a chemical
system,
atmosphere
Analysis
Science,
and oceans,
in
Scientific
via Functional
156,
forest
Groups,
1189-1197,
John
1967.
Simmonds, P. G., F. N. Alyea, C. A. Cardelino, A. J. Crawford, D. M. Cunnold, B. C. Lane, J. E. Lovelock, R. G. Prinn, and R. A. Rassmussen, The atmospheric lifetime experiment, 6, results for carbon tetrachloride based on 3 years of data, J. Geophys. Res., 88, 8427-8441, 1983. Simon, P. C., D. Gillotay, N. Vanlaethem-Meuree, and J. Wisemberg, Ultraviolet absorption cross-sections of chloro- and chlorofluoro-methanes at stratospheric temperatures, J. Atmos. Chem., 7, 107-135, 1988. Simonaitis, R., and J. Heicklen, The reaction of CC1302 with NO and NO2 and the thermal decomposition of CC1302NO2, Chem. Phys. Lett., 62,473-477, 1979. Singh, H. B., Atmospheric halocarbons: evidence in favour of reduced concentration in the troposphere, Geophys. Res. Lett., 4,101-104,
averaged 1977.
hydroxyl
Singh, H. B., and L. Salas, Measurement of selected light hydrocarbons over the Pacific Ocean: Latitudinal and seasonal variations, Geophys. Res. Lett., 4, 842-845, 1982. Singh, H. B., L. J. Salas, and R. E. Stiles, Methyl halides in and over (40°N-32°S), J. Geophys. Res., 88, 3684-3690, 1983.
the Eastern
Singh, H. B., L. Salas, H. Shigeishi, and A. Crawford, Non-urban relationships halocarbons, SF6, N20, and other atmospheric constituents, Atmos. Environ., 819-823, 1977.
Pacific
of 11,
Singh, H. B., R. J. Ferek, L. J. Salas, and K. C. Nitz, Toxic chemicals in the environment: a program of filed measurements, SRI International Report, February, 1986. Singleton, D. L., G. Paraskevopoulos, the extent of H abstraction from 2343, 1980.
and R. S. Irwin, Reaction of OH with CH3CH2F: the A and B positions, J. Phys. Chem., 84, 2339-
Slagle, I. R., J.-Y. Park, and D. Gutman, Experimental investigation of the kinetics and mechanism of the reaction of n-propyl radicals with molecular oxygen from 297 to 635 K, 20th International Symp. Combustion, 1984, The Combustion Institute, Pittsburgh, PA, 733-741, 1985. Slagle, I. R., Q. Feng, molecular oxygen
and D. Gutman, Kinetics of the reaction of ethyl radicals with from 294 to 1002 K, J. Phys. Chem., 88, 3648-3653, 1984.
Smith, F. A., D. E. Gardner, C. L. Yiule, O. H. deLopez, and L. L. Hall, of fluoroacetate in the rat, Life Sciences, 20, 1131-1138, 1977.
R-31
Defluorination
REFERENCES Snider, J. R., and G. A. Dawson, Tropospheric light alcohols, carbonyls, and acetonitrile: concentrations in in the southwestern United States and Henry's law constants, J. Geophys. Res., 90, 3797-3805, 1985. Solvay, Brussels, Milan, Italy, Spence,
Belgium, 1989.
private
J. W., and P. L. Hanst,
communication
J. Air Pollut.
via J. yon Schweinichen,
Control
Assoc.,
Spivakovsky, C., et al., Tropospheric OH and seasonal halocarbons: Separating the influence of chemistry Geophys. Res., 1989.
28, 250,
Montefluos,
1978.
variations of atmospheric and transport, submitted
Stanbury, D. M., W. K. Wilmarth, S. Khalaf, H. N. Po, and J. E. Byrd, thiocyanate and iodide by iridium (IV), lnorg. Chem., 19, 2715-2722,
Oxidation 1980.
Stepakoff, G. L., and A. P. Modica, The hydrolysis of halocarbon refrigerants desalination processes: Pt. I. solubility and hydrolysis rates of Freon 114 (CCIF2CCIF2), Desalination, 12, 85-105, 1973. Stephens, E. R., The formation of molecular oxygen by alkaline peroxyacetyl nitrate, Atmos. Environ., 1, 19-20, 1967.
hydrolysis
to J.
of
in freeze
of
Stewart, R. B., R. T. Jacobsen, J. H. Becker, and M. J. Zimmerman, A survey of the thermodynamic property data for the halocarbon refrigerants, Center for Applied Thermodynamic Studies, Report no. 81-2, University of Idaho, Moscow, ID, 1981. Stier, A., H. W. Kunz, A. K. Walli, and H. Schimassek, metabolism of rat liver by halothane and its metabolite Pharmacol., 21, 2181-2192, 1972.
Effect on growth and trifluoroacetate, Biochem.
Stordal, F., I. S. A. Isaksen, and K. Horntveth, A diabatic circulation model with photochemistry: Simulations of ozone and long-lived sources, J. Geophys. Res., 90, 5757-5776, 1985.
two-dimensional tracers with surface
Stumm, W., and J. J. Morgan, Aquatic Chemistry, an Introduction Emphasizing Equilibria in Natural Waters, 583 pp., John Wiley & Sones, 1970. Suong, J. Y., and R. W. Carr, Jr., The photo-oxidation mechanism of the reaction of CF2CI with oxygen, Swain, C. G., and C. B. Scott, Rates of solvolysis J. Am. Chem. Soc., 75, 246-248, 1953. Swallow,
A. J., Hydrated
electrons
in seawater,
of 1,3-dichlorotetrafluoroacetone: J. Photochem., 19, 295-302,
of some
Nature,
alkyl
222,
fluorides
369-370,
CO emissions: 673, 1977.
Implications
R-32
for the atmospheric
1982.
and chlorides,
1969.
Symonds, R. B., W. I. Rose, and M. H. Reed, Contribution of C1- and F-beating the atmosphere by volcanoes, Nature, 344, 415-418, 1988. Sze, N. D., Anthropogenic cycle, Science, 195,
Chemical
gases
CO-OH-CH4
to
REFERENCES Sze, N. D., and M. K. W. Ko, The effects photolysis on stratospheric chemistry,
of the rate of OH + HNO3 and HO2NO2 Atmos. Environ., 7, 1301-1367, 1981.
Talbot, R. W., M. O. Andreae, T. W. Andreae, and R. C. Harriss, Regional aerosol chemistry of the Amazon Basin during the dry season, J. Geophys. Res., 93, 14991508, 1988. Taylor, W. D., T. D. Allston, M. J. Moscato, G. B. Fazekas, R. Kozlowski, Takacs, Atmospheric photodissociation lifetimes for nitromethane, methyl methyl nitrate, Int. J. Chem. Kinet., 12, 231-240, 1980. Thermodynamics Research Center, TRC thermodynamic A&M University, College Station, TX, 1986.
tables,
and G. A. nitrite, and
non-hydrocarbons,
Tonomura, K., F. Futai, O. Tanabe, and T. Yamaoka, Defluorination of monofluoroacetate by bacteria. Part I. Isolation of bacteria and their activity defluorination, Agr. Biol. Chem., 29, 124-128, 1965. Troe,
J.,
126,
Predictive 1979.
possibilities
of unimolecular
rate theory,
J. Phys.
Chem.,
Texas
of
83, 114-
Tsalkani, N., A. Mellouki, G. Poulet, G. Toupance, and G. Le Bras, Rate constant measurements for the reactions of OH and C1 with peroxyacetyl nitrate at 298 K, J. Atmos. Chem., 7, 409, 1988. Tschuikow-Roux, E., T. Yano, and J. Niedzielsky, atoms with fluorinated methanes and ethanes, U.S.
Environmental
Protection
Agency,
Fed.
Reactions of ground state chlorine J. Chem. Phys., 82, 65, 1985.
Reg. 51, 11,396-11,414,
Reaktion von carbonsaurehalogeniden 1839-1850, 1961.
1986.
Ugi,
I., and F. Beck, Chem. Ber., 94,
mit wasser
Uno,
I., S. Wakamatsu, R. A. Wadden, S. Konno, and H. Koshio, Evaluation of hydrocarbon reactivity in urban air, Atmos. Environ., 19, 1283-1293, 1985.
Vaghjiani, G. L., and A. R. Ravishankara, Kinetics and mechanism CH3OOH, J. Phys. Chem, 93, 1948-1959, 1989. Valtz, A., S. Laugier, and R. Richon, Bubble pressures volumes of difluoromonochloromethane-fluorochloroethane Refrigeration, 9, 282, 1986.
und amiren,
of OH reaction
with
and saturated liquid molar binary mixtures, Int. J.
Varanasi, P., and S. Chudamani, Infrared intensities of some chlorofluorocarbons of perturbing the global climate, J. Geophys. Res., 93, 1666-1668, 1988. Verhoek, F. H., The kinetics solvents, J. Am. Chem.
of the decomposition Soc., 56, 571-577,
Vogel, T. M., C. S. Criddle, and P. L. McCarty, compounds, Env. Sci. Technol., 21,722-736,
R-33
of the trichloroacetates 1934. Transformations 1987.
capable
in various
of halogenated
aliphatic
REFERENCES Volz, A., D. H. Ehhalt, and R. G. Derwent, Seasonal and latitudinal variation in 14CO the tropospheric concentration of OH radicals, J. Geophys. Res., 86, 5163-5171, 1981.
and
Volz,
A., D. H. Ehhalt, R. G. Derwent, and A. Khedim, Messung von atmospharischenn eine methode zur bestimmung der tropospharischen OH radikalkonzentration, KFA Julich Report Jul 1604, Federal Republic of Germany, 1979. 14CO:
Vong, R. J., H.-C. Hansson, H. B. Ross, D. S. Covert, and R. J. Charlson, Northeastern Pacific submicrometer aerosol and rainwater composition: A multivariate analysis, J. Geophys. Res, 93, 1625-1637, 1988. Wada, S. and N. Kokubu, 131-139, 1973.
Chemical
composition
of maritime
aerosols,
Geochem.
J., 6,
Wagman, D. G., W. H. Evans, V. B. Parker, R. H. Schumm, I. Halow, S. M. Bailey, K. L. Churney, and R. L. Nuttall, The NBS tables of chemical thermodynamic properties. Selected values for inorganic and C1 and C2 organic subtances in SI units, J. Phys. Chem. Ref. Data, 11, Suppl. 2, 1-392, 1982. Wallington, T. J., L. M. Skewes, and W. O. Siegl, Kinetics of the gas phase reaction of chlorine atoms with a series of alkenes, alkynes, and aromatic species at 295 K, J. Photochem. Photobiol., A: Chemistry, 45, 167-175, 1988b. Wallington, T. J., L. M. Skewes, W. O. Siegl, C.-H. Wu, and S. M. Japar, Gas phase reaction of C1 atoms with a series of oxygenated organic compounds at 295 K, Int. J. Chem. Kinet., 20, 867-875, 1988a. Wallington, T. J., R. Atkinson, and A. M. Winer, Rate constants for the gas phase reaction of OH radicals with peroxyacetyl nitrate (PAN) at 273 and 297 K, Geophys. Res. Lett., 11,861, 1984. Walraevens, ethanes,
R., P. Trouillet, and A. Devos, Basic Int. J. of Chem. Kinet., 6, 777-786,
elimination 1974.
of HCI from chlorinated
Wang, W.-C., and G. Molnar, A model study of the greenhouse effects due to increasing CH4, N20, CF2C12, and CFC13, J. Geophys. Res., 90, 12,971-12,980, 1985. Wang, W. C., D. J. Wuebbles, W. M. Washington, gases and other potential perturbations to global 1986.
R. G. Isaacs, climate, Rev.
and G. Molnar, Trace Geophys., 24, 110,
Wantuck, P. J., R. C. Oldenberg, S. L. Baughaum, and K. R. Winn, Removal rate constant measurements for CH30 by 02 over the 298-973 K range, J. Phys. Chem., 91, 4653-4655, 1987. Ward, P. F. V., R. J. Hall, and R. A. Peters, Fluorofatty acids Dichapetalum toxicarium, Nature, 201, 611-612, 1964.
in the seeds
Warneck, 1988.
Press,
P.,Chemistry
of the Natural
Atmosphere,
R-34
Academic
Inc.,
of
San Diego,
REFERENCES Waskell, L., Study of the mutagenicity 57, 141-153, 1978.
of anesthetics
and their metabolites,
Mutation
Res.,
Watson, R. T., A. R. Ravishankara, G. Machado, S. Wagner, and D. D. Davis, A kinetics study of the temperature dependence of the reactions of OH (21-/) with CF3CHC12, CF3CHC1F, and CF2C1CH2C1, Int. J. Chem. Kinet., 11, 187-197, 1979. Watson, R. T., G. Machado, B. Conaway. S. Wagner, and D. D. Davis, A temperature dependent kinetics study of the reaction of OH with CH2CIF, CHCI2F, CHCIF2, CH3CC13, CH3CF2C1, and CF2C1CFC12, J. Phys. Chem., 81,256-262, 1977. Watson, R. T., M. J. Prather, and M. J. Kurylo, Present state of knowledge atmosphere 1988: An assessment report (to Congress), NASA Reference 1208, 1988. Weast, R. C., ed., CRC handbook Raton, FL, D-194, 1977. Weber, L. A., Vapor J. Thermophysics,
of chemistry
and physics,
57th
ed., CRC
Press,
Boca
pressures and gas phase PVT data for 1,1,1,2-tetrafluoroethane, 10, no. 3, to be published, 1989.
Weber, L. A., and J. M. H. Levelt-Sengers, Critical parameters 1,1-dichloro-2,2,2-trifluoroethane, to be published, 1989. Weinstein,
of the upper Publication
L. H., Fluoride
and plant life, J. Occup.
Med.,
and saturation
19, 49-78,
Int.
densities
of
1977.
Weinstein, L. H., D. C. McCune, J. F. Mancini, L. J. Colavito, D. H. Silberman, and P. van Leuken, Studies on fluoro-organic compounds in plants. III. Comparison of the biosyntheses of fluoro-organic acids in Acacia georginae with other species, Environ. Res., 5, 393-408, 1972. Weinstock, B., The residence 224-225, 1969. Weinstock, 1972. Whytock,
time of carbon
B., and H. Niki, Carbon
monoxide
D. A., and K. O. Kutsche,
Proc.
monoxide
balance
Roy.
in the atmosphere,
Science,
in nature,
176,
Soc. A., 306,
Science,
503,
Wilkness, P. E., and D. J. Bressan, Chemical processes at the sea-air behavior of fluorine, J. Geophys. Res., 76, 736-741, 1971.
166,
290-292,
1988. interface:
The
Wilkness, P. E., and D. J. Bressan, Fractionation of the elements of F, C1, Na, and K at the sea-air interface, J. Geophys. Res., 77, 5307-5315, 1972. Wilmarth, W. K, D. M. Stanbury, J. E. Byrd, H. N. Po, and C.-P. transfer reactions involving simple free radicals, Coord. Chem. 1983. Wilson, D. P., and R. S. Basu, working fluid--refrigerant Wilson,
S. R., P. J. Crutzen,
Thermodynamic 134a, ASHRAE G. Shuster,
properties of a new stratospherically Trans. 94 pt. 2, 1988.
D. W. T. Griffith,
R-35
Chua, ElectronRev., 51, 155-179,
and G. Hale_,
Vature,
safe
1989.
REFERENCES Wine, P. H., and W. L. Chameides, Possible atmospheric lifetimes and chemical reaction mechanisms for selected HCFCs, HFCs, CH3CCI3, and their degradation products against dissolution and/or degradation in seawater and cloudwater, AFEAS manuscript, June, 1989. Wine,
P. H., Y. Tang,
R. P. Thorn,
phase reactions of the SO4-radical Geophys. Res., 94, 1085-1094,
J. R. Wells,
and D. D. Davis,
with potential 1989.
importance
Kinetics
in cloud
of aqueous
chemistry,
J.
Winer, A. M., K. R. Darnall, R. Atkinson, and J. N. Pitts, Smog chamber study of the correlation of hydroxyl radical rate constants with ozone formation, Environ. Sci. Technol., 13, 822-826, 1979. Winer, A. M., R. Atkinson, and J. N. Pitts, nighttime atmospheric sink for biogenic 1984.
Jr., Gaseous nitrate organic compounds,
radical: Possible Science, 224, 156-159,
Withnall, R., and J. R. Sodeau, Applications for Fourier transform IR spectroscopy determination of photo-oxidation quantum yields for halocarbons, J. Photochem., 1-11, 1986. Witte, L., H. Nau, and J. H. Fuhrhop, Quantitative analysis fluids of patients treated with halothane, J. Chromatog.,
of trifluoroacetic 143, 329-334,
to the 33,
acid in body 1977.
WMO, Atmospheric ozone 1985: assessment of our understanding of the processes controlling its present distribution and change, WMO Report No. 16, sponsored by WMO, NASA, NOAA, FAA, UNEP, CEC, and BMFT, Washington, DC, 1986. Wofsy, S. C., and M. B. McElroy, HOx, NOx, and C103: Their photochemistry, Can. J. Chem., 52, 1582-1591, 1974. World
Health
Organization,
Fluorine
and fluorides,
36, 1-136,
role in atmospheric
1984.
World Meteorological Organization, Atmospheric ozone 1985: assessment of our understanding of the processes controlling its present distribution and change, WMO Report No. 16,Vol. 1, 117-150, sponsored by WMO, NASA, NOAA, FAA, UNEP, CEC, and BMFT, Washington, DC, 1986. Wu, D., and K. D. Bayes, Rate constants cyclopentyl, and cyclohexyl radicals 547, 1986.
for the reactions of isobutyl, neopentyl, with molecular oxygen, Int. J. Chem. Kinet.,
Wuebbles, D. J., The relative efficiency of a number of halocarbons for destroying stratospheric ozone, Rep. UCID-18924, Lawrence Livermore Nat. Lab., Livermore CA, 1981. Wuebbles, ozone,
D. J., Chlorocarbon J. Geophys. Res.,
emission scenarios: Potential 88, 1433-1443, 1983.
Wuebbles, ozone, 1988.
D. J., and D. E. Kinnison, Proc. Quadrennial Ozone
impact
on stratospheric
A two-dimensional study of past trends in global Symposium, Univ. of Gottingen, Rep. of Germany,
R-36
18,
REFERENCES Wuebbles, D. J., K. E. Grant, P. S. Connell, chemistry in climate change, J. Air Poll. Xing
Lin and W. L. Chameides, stratiform cloud, submitted
and J. E. Penner, The role of atmospheric Control Assoc., 39, 21-28, 1989.
Model simulations of rainout to J. Atmos. Chem., 1989.
and washout
from a warm
Yamashita, T., H. Kubota, Y. Tanaka, T. Makita and H. Kashiwagi, Measurements physical properties of new fluorocarbons, Proc. Ninth Japan Symp. on Thermophysical Properties, 227-230, 1988. Zafiriou, Res.,
O. C., Reaction of methyl 33, 75-81, 1975.
Zafiriou, O. C., and M. B. True, 8, 9-32, 1979.
halides
Nitrite
with sea water
photolysis
and marine
in seawater
aerosols,
by sunlight,
of
J. Marine
Mar.
Chem.,
Zander, M., Pressure-volume-temperature behavior of chlorodifluoromethane (Freon 22) in the gaseous and liquid states, Proc. 4th Symp. on Thermophysical Properties of Gases, Liquids, and Solids, ASME, 114-123, 1968. Zellner, R., and L. Jiirgens, be published, 1989.
Photooxidation
of CHC1F2
under
tropospheric
conditions,
to
Zepp, R. G., A. M. Braun, J. Hoigne, and J. A. Leenheer, Photoproduction of hydrated electrons from natural organic solutes in aquatic environments, Env. Sci. Technol., 21, 485-490, 1987a. Zepp, R. G., J. Hoigne, chemicals in water,
and H. Bader, Nitrate-induced photooxidation Environ. Sci. Technol., 21,443-450, 1987b.
of trace
organic
Zhang, K., D. Chen, G. Liu, Y. Xu, and Y. Hu, Solubilities of chloro-difluoromethane and tetrafluoroethylene in aqueous solutions of HC1 and NaC1, Journal of East China Institute of Chemical Technology, 1985.
R-37