with chemical and physical properties of PAH as well as the sources, ...... grass or bush fires (Standley and Simonett, 1987). On the ...... John Wiley and Sons Inc.
IP ic
POLYCYCLIC AROMATIC
HYDROCARBONS: SOURCES, FATE AND LEVELS
WATER,
FOOD
MAY
IN
SOIL,
AIR,
SEDIMENTS, SLUDGE AND
ONTARIO
1992
Environment Environnement Ontario
IN
ISBN 0-7729-9281-9
POLYCYCLIC AROMATIC HYDROCARBONS: SOURCES, FATE
AND LEVELS
IN AIR,
SLUDGE AND FOOD
WATER,
IN
SOIL,
SEDIMENTS,
ONTARIO
Report Prepared For:
Hazardous Contaminants Branch
Report Prepared By:
Concord
Scientific Corporation
and
Beak Consultants
MAY
1992
o
PRINTED ON RECYCLED PAPER
IMPRIMESUR OU PAPIER RECYCLE
Cette publication technique n'est disponible qu'en anglais.
Copyright: Queen's Printer for Ontario, 1992
This publication
may be reproduced
for
non-commercial purposes
with appropriate attribution.
PIBS 1938
DISCLAIMER This report has been approved for publication by the Hazardous Contaminants Branch of the Ontario Nlinistry of the Environment. Approval does not signify that the contents necessarily reflect the views and policies of the Ontario Ministry of the Environment, nor does the Ministry warrant the information contained herein. Mention of trade names or commercial products does not constitute endorsement or
recommendation
for use.
EXECLTTIVE
SUMMARY
This report covers a review of literature information on polycyclic aromatic
hydrocarbons (PAH),
and physical properties
with chemical
inputs
and
Good,
reliable
fate of
PAH
data
for
Specifically, this report deals
primarily in Ontario. of
PAH
as well as the sources,
to the environment.
PAH
physical properties are scarce. For example,
recorded vapour pressure data frequently range over several orders of
magnitude and existent.
The
solubility
data
Similarily, reliable,
in
solvents other than water are often non-
chemical
report discusses the sources
reactivity
and input
data are equally scarce.
to the
environment by
compiling the emission factors and profiles for point and non-point
sources
in
Ontario.
these compounds,
atmosphere
Based on the atmospheric emissions inventory it
is
estimated that the major
to the
are:
o
Gasoline and diesel fuelled vehicles
o
Forest
o
Woodburning stoves and
fires
fireplaces
These three sources contribute approximately 97%
MT/y
PAH sources
for
of total
PAH atmospheric
emissions
in
of the estimated
Ontario.
260
The remaining
contributions are primarily from industrial operations (including coke
manufacturing, coal-fired thermal generation stations and incinerators)
and
residential,
PAH
emission
because
of
commercial and is
institutional heating.
The estiamted
total
believed to be uncertain by a factor of about two,
data limitations.
The emission
factors for
PAH
that are major contributors to the total
from these sources are summarized its
Phenanthrene and
Table ES-1.
in
methyl derivatives, pyrene, anthracene and
its
PAH
methyl derivatives and
benzo[a]pyrene are the most ubiquitous based on the number of entries in
On
the Table.
the other hand, benzo[k]f!uoranthene
is
only recorded
once; so too, are perylene, fluorene, dibenz[a]anthracene and derivatives
and
Whereas,
benzo[e]pyrene.
benzo[k]fluoranthene
was produced
was
it
its
methyl
noted
that
a relatively high concentration
at
in
coke oven emissions, the information obtained during the study provided
no guide regarding
potential
PAH source
markers.
Indeed, this review
discoverd no recorded unambiguous procedure for identifying chemical
markers that could be
The
report also discusses sources
estimated that nearly
from
clearly attributed to a specific source.
rainfall;
75%
of the
and inputs
PAH
and
to water
loadings to
soil
soil,
and
and water
it
is
arise
the remaining inputs are from industrial discharges, including
water pollution control plants, and there
is
also a significant contribution
to water arising from urban run off (10-15%).
PAH
that are
most persistent and frequently detected
at relatively
concentration
in
and pyrene
treated discharge from water treatment plants,
in
water include benz[a]anthracene, benzo[k]fluoranthene
an extensive study carried out on 37 high flow rate sludges produced from these
facilities
also
plants.
showed higher
based on Similarly,
levels of
acenaphthylene, phenanthrene, and pyrene, compared to the other detected.
high
PAH
s 5
3
I
M>^3 5
Formula
4
*
»
* d * \^ d ^ d d IcdccdcddcdScddcddddcddoddd dc)«>d•-d^—
d^--.-Wriiccccdcc-^d>-ddcC'- fluoranthene > B[a]P
in
in
contrast to the order
nitration
mechanism
of nitration
therefore different from that
(Pitts et al.,
1985a).
by N2O5
is
nitration of in
PAH
was estimated
More recent studies recognize Pitts et al.,
OH
reactions
by N2O5
at
PAH. A
1.8%
(Pitts et al.,
The
nitration of
be due to N2O5
Pitts
et
HNO3 exclusively
(Pitts et al.,
solution
in
its
view of role
in
pyrene
1985b).
1986; Atkinson et
al.,
1986;
well as the role of
perylene and pyrene by NgOg rather than
by NO3 was demonstrated by implicating nitration by
in
nitration rate for
NO3 as
The
solution.
important
h'^ (Pitts et al.,
1985b) the importance of N2O5 and
radicals.
is
in
the atmosphere and, therefore,
influencing the atmospheric lifetime of at night
in
PAH towards
expected on the basis of the
the presence of NgOg
The
difficult.
> benz[a]anthracene > perylene > chrysene,
The
PAH
estimation of their
product distribution
mine the rates and mechanisms
The
make
nitrations.
on chamber studies and
relied
of the nitroarene
polluted atmospheres.
of the particle-bound
from the solution phase
nitration reactions are different
by N2O5
some
relative rate information that is consistent with the nitration
solution, the rates
influence
While
various 'model' substrates.
of the laboratory investigations of
nitration
1986).
al.
(1986) and earlier studies
(Grosjean, 1983) were
shown
to
5-10
Nitro-PAH found
in
ambient
air
include 1-
and 2-nitronaphthalene,
1-
and
4-
nitropyrene, 2-nitropyrene, 2-nitrofluoranthene, 3-nitrobiphenyl
The two most abundant
nitrobiphenyl.
particulate nitro-PAH
samples are 2-nitrofluoranthene and 2-nitropyrene, and has been ascribed to atmospheric
their
nitration reactions (Arey et
The nitro-PAH isomers found
radicals
the presence of
in
NO^
(Atkinson et
The most abundant nitro-PAH found
1987).
been shown
be the more
to
volatile,
presence al.,
1987)
the atmosphere are
in
consistent with the their formation through reactions of parent
OH
ambient
combustion sources (Tokiwa and
rather than to direct emissions from
Ohnishi, 1986).
in
PAH
with
1987; Arey et
al.,
al.,
ambient samples have
in
vapour-phase nitro-PAH such as
nitronaphthalene and 3-nitrobiphenyl (Arey et
These isomers
1987).
al.,
2-
are not those expected from electrophilic nitration reactions of the parent
PAH, but
atmospheric
nitrating
Measurements
the presence of
in
of nitro-PaH at industrial
(Bermuda) than
The
species (OH
concentrations
nitropyrene
1986).
as a result of the atmospheric transformation by
rather,
at sites
ratio of
higher
at
the
near industrial sources
B[a]P to
TSP
B[a]P/TSP
ably higher than
were
and remote
at sites
in
NO^ and
NgOg).
showed
that 1-
sites
most remote
site
Michigan (Gibson,
near the sources were consider-
ratios at the distant
sources which indicates
the importance of the transformation reactions of B[a]P during transport.
The formation
The more
of 1-nitropyrene during transport
volatile
with respect to
PAH
OH
are abundant
and
was suggested.
the atmosphere and their lifetimes
in
nitration reactions are
expected to be
of the
order of 9 h for phenanthrene and 2 h for anthracene (Bierman et 1985; Atkinson, 1986). involving
OH
reaction
with
radicals
NjOg,
nitrofluoranthene
The formation in
of nitro-PAH
al.,
by two pathways, one
the presence of NO^, and the other due to
have
been
shown
and 2-nitropyrene (Arey
et
to al.,
be
important
1986).
for
2-
Estimates of the
5-11
OH/NO^ and
fluoranthene with respect to the
half lives of
the NjOg
reactions (under southern California conditions) were approximately 6 h
and 7 weeks
respectively.
O3 concentrations
Ontario urban atmospheres, NO,
In
>500 and 90 ppb
of 400,
been
respectively have
observed
-
trations of
naphthalene (vs 2800 ng/m^), fluoranthene (vs 9.7 ng/m^) and
pyrene
similar to
those
ng/m^)
(vs 12
for
Southern California and ambient concen-
in
example are
with respect to these reactions
determined
The
for
more southerly
fate of the nitroarenes
nitration reactions,
PAH. The
needs
to
in
Ontario
air
in
formed
of the nitroarenes
and 6,12- isomers
Finlayson-Pitts
and
Pitts
(1986) proposed a
and the
photolyses of the 6-nitroB[a]P and 1-nitropyrene
of 9,10-
of
-
B[a]P
for other
scheme
to
relatively rapid
both of which are
polluted atmospheres, are consistent with the predictions.
Further work
is
needed
those formed
in
atmospheric
Reactions with
The
atmospheric
The photolysis
predict the relative photolysis rates for nitroarenes,
in
in
Analogous photoxidation products are expected
nitroarenes.
PAH
forms the 9,10-anthraquinone,
silica gel)
while 6-nitroB[a]P forms the 1,6-, 3,6-,
present
parent
the overall assessment of
indicates that quinone products are formed.
quinones.
1987).
could be similar to those
on the photochemistry
nitroanthracene (absorbed on
al.,
under certain conditions.
latitudes,
be considered
limited information
et
half lives of the
especially those
-
Arey
similar (see
Thus the nitroarene concentrations and the
5.1.1.3
NO^ and
solution
to establish the fate of nitroarenes
-
especially
nitration reactions.
Ozone
phase reactions
system on which some Ozonolysis of B[a]P
of
B[a]P with ozone provide a simple model
of the reactions of in
solution
ozone
with
PAH may be
(methylene chloride, 3:1
based.
methylene
5-12
chloride-methanol) forms the 3,6- and 1,6-diones of B[a]P. With excess
ozone, more highly oxidized products 7H-benz[d,e]anthracen-7-one 3,4dicarboxylic and et
1961).
al.,
acid are formed (Moriconi
was
Confirmation of the mechanism
schemes
of three
most
1, 2-anthraquinonedicarboxylic
ozone
involving a two-step electrophilic attack by
reactive centres
(i.e.,
one
not feasible but
carbons with the lowest carbon
at
the
localization
energies) to give a sigma complex followed by nucleophilic 1-4 addition to give a primary ozonide
and thence
to p-quinones
was thought
to
be
applicable.
PAH
Several investigators have exposed
(from
previously collected
ambient or source particulates or pure compounds deposited on or evaporated onto glass surfaces) to
1979;
1980a; Peters and
Pitts et al.,
1983; Brorstroem et 1983).
few
al.,
ozone (Lane and Siefert,
1983a; Grosjean
et
B[a]P
and
diphenols
Cauwenberghe including
et
B[a]P-phenol
1979;
al.,
dialdehydes,
contrast, Grosjean et
al.
The
al.,
exposed
of the
al.
and
reagent PAH, but
(1,6-, 3,6-
(Pitts et al.,
and 6,-12
(1983), B[a]P dihydrols,
B[a]P-quinones
(van
compounds
1979) and ring-opened acids,
et
ketocarboxylic acids and
1980a) were also
identified.
In
(3
hours, 100
ppb ozone) were
milder than
previous studies.
relative rates of
to
disappearance of several
ozone were found
identified
to
PAH
in
diesel particulates
be consistent with electron density
Vaeck and van Cauwenberghe,
1984).
No products
and the data were consistent with
earlier
work by Lane
calculations (van
were
1983b; Lindskog
al.,
(1983b) found no evidence of reaction, but the
exposure conditions used in
Pitts,
dicarboxylic
benzo[a]pyrene-4,5 oxide
those
al.,
B[a]P quinones
isomers) were identified by Rajagapolan et
Katz, 1977; Pitts,
1980: Rajagapolan et
Most studies reported the disappearance
identified reaction products.
filters
5-13
and Katz
The presence
(1977).
The most
oxy-PAH
PAH by ozone
suggests the oxidation of determining the nature of
of several
compounds found
in
particles
in
the dark (Table 5-3).
exposed
to
300 ppb O3, ranged from 30
was found
to
in
PAH have
which
The
ozone (540 ppb),
to
half lives of
to
NOg in
60 minutes. The reaction
be very temperature dependent - the
half
life
et
intensities,
1986).
al.,
PAH decay
such as would apply
half lives to several hours.
ozone reactions
5.1.1.4
in
PAH
the dark of
B[a]A
decreasing by
a factor of four to ten for temperatures decreasing from 20
(Kamens
PAH from
reacted with ozone and nitrogen oxides under natural
daytime solar radiation and
on woodsmoke
in
ambient samples.
in
relevant investigations of the atmospheric stability of
woodsmoke were
to
be important
could
been derived from outdoor reaction chamber studies
and
ambient samples
to -7°C
lower temperatures and solar
at
Ontario, therefore, would extend the
The more complete
with a wider range of
PAH
is
characterization of the
needed.
Reactions with Sulphur Oxides
The
PAH
reactions of
with sulphur oxides
Jager and Rakovic (1974), Hughes (1981),
Tebbens
et
PAH absorbed on sulphur-containing
al.
fly
(1966)
et
al.
and Grosjean
have been investigated by (1980), Butler et
al.
and Crossley
(1983a).
ash or alumina reacted with SO2 to form several
compounds
including pyrene-1-sulphonic acid, pyrene-
disulphonic acid, B[a]P-sulphonic acid (Jager and Rakovic, 1974).
5-14
TABLE
5-3
Outdoor Chamber Studies of PAH Reactions with O3, NO2 and hv^
PAH
^
hv^
Pyrene
Half Life (minutes)
200 ppb 03^
c^nn onK 500 ppb
K\r^ NO/
5-15
In contrast,
alumina,
Hughes
silica
et
al.
identified)
The
et
Similar studies by
unidentified products.
Crossley (1981), but with
Tebbens
PAH adsorbed on
al.
PAH on
showed no
soot,
ash,
to SOj, but
Butler
due
and
to SOj,
(1966) did report degradation of B[a]P (products not
phase reaction
of
anthracene with SO2
yielding anthracene-9-sulphonic acid (Nagai et
reacts with concentrated et
possible for
1937).
al.,
PAH
in
H2SO4
al.,
photocatalyzed
is
1986).
Pyrene also
to give a mixture of sulphonic acids
These reactions suggest
to react with
SO2
or
H2SO4
in
that
it
is
theoretically
the environment to form
These water soluble compounds have not been
sulphonic acids. identified
effect
fly
by SOj.
solution
(Valkman
coal
and activated charcoal, found no reaction due
SO3 produced
but
(1980) using
ambient samples but
this
may be due
to
the
use
of
inappropriate solvents for the extraction of ambient particulates (Nielsen et
al.,
1983b).
If
any sulphonic acids formed react
sulphonates, extraction methods used
in
further to form
the above studies to isolate
sulphonic acids would miss the sulphonates.
5.1.1.5
Photolysis of
PAH Compounds
The photochemistry
of
PAH has been
studied for
many
years.
The low
temperature solid state photochemistry of condensed hydrocarbons has provided a wealth of information on the spectroscopic properties of
molecules and the photophysical processes subsequent to absorption of photons. Of importance to the photochemistry of is
PAH
in
the environment
information on the accessibility and stability of excited photochemical
states. late
PAH
in
environmental matrices are adsorbed to the
fine particu-
matter and effects of the sorbent on the photochemical properties of
PAH
are
likely to
be important.
5-16
The
solid state photolysis of the
photochemistry are
pure
PAH
as well as
their solution
but the photochemistry of
limited,
phase
PAH adsorbed on
various real-environment and model sorbents has been studied by several investigators.
The
photolysis
PAH
pure
of
benzo[k]fluoranthene) deposited on
and Katz
(1977).
and reaction
They pointed out
likely to affect
intensity of the light
that surface reactions (photolysis
in
onto which
The
the photoreactivity.
source used were
substrate (solutions of
as present
was reported by Lane
with ozone, for example) are likely to
effect of the nature of the particles
therefore
dishes
petri
and
benzo[b]fluoranthene
(B[a]P,
PAH evaporated
The
be important.
PAH
are absorbed
in petri
and
spectral distribution
similar to sunlight, but the
dishes)
was
is
PAH same
not the
natural conditions.
Sorbents used have been soot (Thomas 1971), particles on glass fibre
filters
et
al.,
1968;
Tebbens
et
a!.,
(Fox and Olive, 1979; Peters and
1980a), coal
fly
ash (Jager and Rakovic, 1974;
Jager and Hanus, 1980; Korfmacher
et
al.,
1980;
Siefert,
Hughes
et
al.,
microneedles
Pitts et al.,
1980b; Wehry
1980; Blau and Gusten, 1982),
(Barofsky
chromosorb (Eisenberg
and Baum, et
al.,
1976),
1983) and
Oxidation products were identified
in
silica gel,
1976).
and
1967).
the photolysis of anthracene, B[a]A,
and on carbon needles (Barofsky and Baum, 1976).
Baum,
1984;
alumina, carbon
B[a]P, pyrene, perylene and fluoranthene on soot (Tebbens et
coronene photolyzed under
al.,
particulates
diesel
soil (Fatiadi,
et
similar conditions
al.,
1971)
Chrysene and
were stable (Barofsky and
5-17
In contrast, later
of
chrysene
work (McCoy and Rosenkranz, 1980) on the photolysis
(as
as 3-methylcholanthrene) yielded unidentified
well
products that were shown to have increased mutagenetic
was
postulated that the
triplet
A
state of the
photooxidation
mechanism
PAH and
suggested also (Fox and
Olive,
oxygen.
involving singlet molecular 1
It
of the photooxidations involved the
singlet molecular
mechanism
activities.
oxygen was
979) for photolyses of anthracene spiked
onto previously collected ambient particulates. The products implicated anthraquinone,
included
photodimer.
bianthryl
the
or
anthracene
(1979) also suggested electrophilic attack by singlet
Pitts
oxygen
molecular
anthrone,
was
likely
be
to
an
mechanism
important
in
photooxidation of PAH.
Eisenberg of
et
PAH by
al.
(1983) presented evidence consistent with the oxidation
singlet
oxygen according
to the following
mechanism (where
the * indicates an electronically excited species):
O2
PAH + h.--> PAH* PAH
Several singlet
—
>
PAH +
O2* -->
oxy-PAH
as well as diesel particulates were found to be
oxygen
sensitizers.
Model compounds (9,10-diphenylanthracene
and chrysene) absorbed on Chromosorb 102 reacted singlet
occur
oxygen in
to form
oxy-PAH products.
the atmosphere.
efficient
in
high yield with
Similar reactions are likely to
Fatiadi (1967) also postulated the reaction of
photoexcited pyrene molecules with adsorbed oxygen.
The
reduced
photosensitivity,
anthracenes adsorbed on coal silica gel
especially fly
of
B[a]P,
pyrene
and
ash particles compared to alumina,
or the pure solid (or even
PAH
in
solution),
was reported by
5-18
Korfmacher
et
al.
presumably
photosensitivity,
resulting
into
account
reduced
this
from the energetics of surface
adsorption, the presence of
PAH on
coal
environment would imply long
lifetimes.
Thus, the persistence of
Gusten, 1982).
presented
in
Illustrative
half-life
directly to the
in
is
particles
in
feasible (Blau
the
PAH and
Table 5-4.
The previous discussion has be emitted
ash
data for different substrates are
Concentrations of Oxy- and NItro-PAH
reactions
fly
range transport of submicron particles
after long
5.1.1.6
Taking
(1980a).
the
in
the Atmosphere
indicated that both oxy-
and nitro-PAH may
atmosphere or may be formed from PAH by
open atmosphere.
There
is
predominant nitro-PAH are not those related
some evidence
to direct emissions, but,
Observed
instead, are the result of atmospheric nitration reactions.
concentrations
in
ambient
air,
then,
will reflect
that the
contributions from
many
sources and processes.
Only recently have sampling and analytical methods achieved levels of to
reliability
for
PAH
which would allow ambient monitoring data
be accepted with confidence.
Thus, historical results ought to be
interpreted as qualitative illustrations of
compound
identifications
atmospheric processes, rather than as quantitative data estimation purposes.
derivatives
See Davis
etal. (1986)
(1986) for discussions of this point.
for
and
exposure
and Finlayson-Pitts and
Pitts
5-19
TABLE
5-4
Hours) for the Photolysis of PAH on Different Substrates Determined in the Rotary Photoreactor (Approximately 25 ug of Each PAH/g of Substrate, Except for the Carbon Black) Half-Lives
(in
5-20
Both oxy- and nitro-PAH have been
identified in the air of Ontario cities
(D'Agostino, 1983; Nielsen, 1983; Nielsen et
1982; Pierce and Katz, 1976; Davis et
al-,
1983a; Ramdahl et
ai.,
al.,
Systematic studies,
1986).
however, have not been carried out to allow conclusions about
typical,
average or peak concentrations.
Table 5-5 shows ranges of measured ambient selected nitro-PAH, for
data that of
many
some
purposes.
illustrative
nitro-PAH are present
in
It
air
concentrations of
appears from available
concentrations similar to those
unsubstituted PAH.
The concentrations
of
oxy-PAH may be comparable
highly polluted areas (Konig et
concentrations of
PAH and
al.,
1983a).
to those of B[a]P in
Relationships between the
their respective oxidation products, e.g., for
B[a]P, B[a]A and their respective quinones, indicate that atmospheric oxidation takes place, especially
In
in
summer
(Pierce
other cases, the similar profiles of oxy-PAH
samples show that the sources, for the
PAH
presence
in rural
of
oxy-PAH
in
in
in
and
Katz, 1976).
ambient and
particular diesel exhausts,
in
source
can account
ambient samples. The absence of oxy-
samples, while present
in
urban samples (Tanner and
Fajer,
1983), lends support to urban sources, especially automobile emissions,
as major contributors to ambient levels of oxy-PAH.
5-21
TABLE Ambient Concentrations
Compound^
1-NP
Location
5-5 of Selected Nitro-PAH
Concentration (ng/m^)
Reference
5-22
The temporal for the parent
variability of
oxy- and nitro-PAH
PAH. The higher
levels
seem
is likely
likely in
to
be
winter
similar to that
months (due
reduced dispersion and lower chance
to increased emissions,
and photochemical degradation), but lower
of thermal
summer
levels are likely in
(although higher ratios of oxy- and nitro-PAH to parent
PAH may
obtain).
Other than data by Pierce and Katz (1976), there are no other data to support the above hypothesis.
Pitts
et
al.
(1982) found that there
particulate mutagenicity that
is
is
a diurnal variation of ambient
similar to that of primary pollutants,
as
evidenced by the high correlation of mutagenicity of 3-hour average
samples with CO, NO^ and Pb concentrations. The short-term average) peak mutagen
activities of particles
(3
hour
were much higher than the
24-hour average values, but there was agreement between the average of the 3-hour
was
5.
1
.2
samples and the 24 hour samples. The diurnal
not observed
in
a subsequent study
Long Range Transport
The dispersion
of
(Pitts et al.
variation
1985c).
PAH
of pollutants
by long range transport
is
well
known
for
inorganic species, e.g., sulphates, nitrates, and also for organic pollutants
such as PAH.
Given the
common
expected that long range transport determining the distribution
formed during transport.
PAH and
sources will
of
PAH and oxy-PAH,
it
is
also be an important factor
in
of their oxy-
and nitro-PAH products
5-23
Mesoscale and long range transport
been demonstrated
o
PAH
profiles (relative
abundances)
al.
PAH were
indicated
of
PAH
(1983)
contrast,
in
Riso,
and
sites;
of
PAH.
1
sites, in
concentrations
was thought
-nitropyrene
of B[a]P,
1
for
known sources.
be
insignificant.
to
-nitropyrene
1
-nitropyrene during LRT.
at the
source)
was up
remote
site.
compared
In
and marker inorganic at
near-source and
conjunction with back trajectory determination, indicated
remote
site
to
In
fact,the
1
were higher than B[a]P
Also, the ratio of B[a]P to
site.
nitro-and parent
Denmark. This was based on comparisons
ambient samples with those
measurements
the formation of
remote
remote
and organic (elemental carbon (EC)) species,
(Pb, Se)
remote
at
showed that mesoscale transport of
profiles of
Transformation of
oxy- and nitro-PAH have
by:
the presence of
Nielson et
PAH and
of
TSP
-nitropyrene levels at the
at the industrial site (near-
250 times higher than the B[a]P/TSP
The lower B[a]P/marker
to the near-source sites,
is
ratio
at the
ratio at the
remote
site-
as
consistent with the reaction of
B[a]P during transport, but the disappearance of B[a]P appeared to stabilise in
aged aerosols (Gibson and
due
of
The changing
ratio
B[a]P/TSP was, undoubtedly, also influenced by the
of particle-bound
enhancement
Wolff, 1985).
vapour-phase B[a]P as TSP concentration decreased
to dispersion.
Daisey and Kreip (1979) also suggested that the Long Range Transport (LRT) of
PAH
a reference its
into
New York
in
may be
important.
compound showed behaviour
rapid degradation by
PAH
City
The use
of
B[a]P as
contrary to the expectation of
O3 and HNO3; thus the
ratio of
B[a]P to other
ambient samples increased instead of decreased
relative to
5-24
source measurements. The increased that
LRT under
Bjorseth
et
ratio
certain meteorological conditions
indicated
(1979)
al.
concentrations of
PAH
LRT
The higher
dispersion
basis for concluding
was
likely.
Europe, since the
in
varied significantly with origin of
winter
(lower
PAH
of
there were correlations of peak levels of soot).
was the
PAH
mixing
levels
PAH
with other pollutants (SO4,
were assumed
and
heights)
masses, and
air
a
be due
to
reduced
to less
likelihood
of
photochemical degradation.
Lindskog and Brorstroem (1981) also asserted that the presence of high concentrations of B[a]P also
used
the
was
absence
indicative of
little
methylated
of
concentrations of B[a]P, to support LRT. of
PAH,
together
with
low
Similarly, the high correlation
B[a]P concentrations with soot levels together with back trajectories
was used
5.2
chemical degradation, but
to distinguish
between
local
and
distant sources.
Soil
The
available information
shows
concentrations near a steel
highway, as well as
waste disposal
site at
in
mill
soils
that
PAH occur
in
Ontario soils at higher
source (Sault Ste. Marie), near a Toronto
and sediments around a coal
Port Stanley, as described elsewhere
gasification
in this
Atmospheric deposition through PAH-contaminated
rainfall
measured
PAH occur
Ontario
in
soils,
volatilization
southwestern Ontario.
and processes
Undoubtedly,
has also been
of adsorption, biodegradation
and photolysis influence the
fate of
PAH
in
report.
the
widely
in
and possibly soil.
5-25
5.2.1
Degradation
Soil
in
Soils
microorganisms are capable
as documented
in
of metabolizing
reviews by Radding et
Overcash (1983) and Bulman
et
al.
al.
PAH to varying
(1976), Neff (1979),
in soils.
The former type
responsible for
PAH
indication of "fate"
Bulman
et
degradation.
al.
type provides a better
metabolic
the
pathways
of
PAH
Monooxygenases and dioxygenases are enzymes which
catalyze the incorporation of
one
or
two oxygen atoms
The intermediates formed
structure.
latter
world conditions.
real
reviewed
(1985)
PAH disappearance
of study provides insight into the species
metabolism, while the
under
Sims and
Biodegradation studies have
(1985).
included both measurements of total and specific rates
degrees,
in
into the
PAH
ring
these pathways undergo further
dihydroxylation steps that lead to the eventual cleavage of the aromatic
and degradation
ring
of the resulting
phenols and carboxylic acids.
Culture studies have also demonstrated that
biodegradation
may be
readily
degraded
in
some PAH
resistant to
the presence of other
PAH
which support microbial growth, indicating that these more resistant forms
may be
cooxidized
in
PAH
mixtures occurring
in soils,
sediments and
sludges.
Several investigators have measured degradation accurately, disappearance) rates of
PAH
in soils,
(or
perhaps, more
although variations
in
experimental conditions and analytical techniques have caused problems in
defining degradation rates
rates
may
rates
(i.e.,
competing physical
Overcash (1983) reported for
environments.
Measured removal
also be influenced by the superposition of slow solubilization
and desorption
days
in soil
PHEN, 3
to
half-lives of 3.3 to
35 days
for P,
rate processes).
175 days
44 to 182 days
for
Sims and
for A, 2.5 to
26
F and 4 to 6,250
5-26
days
CHR
Studies with
for B[a]A.
and B[a]P have reported
half-lives
as
low as 5.5 and 2 days, respectively while other studies have indicated no degradation (Bulman degradation to
182 days
for
A and
et
marsh sediment
A and 105
for
Herbes (1981) reported
half-lives of 1.8
and 8.8 days
B[a]A, respectively, but no degradation of B[a]P,
(1984) observed biodegradation of
20 to
(1979) reported
al.
108 to 175 days
exposed sediment downstream from a coking
of
et
of
half-lives in
for F.
Gardner
1985).
a!.,
30%
per week.
In
FLN
pre-
in
plant discharge. Lee et
al.
subsoil near a creosoting plant
in
a study of degradation rates
in
sediments from
a contaminated stream, Herbes and Schwall (1978) measured rate constants
(h"^) of
2.5 x 10'^,
1
x 10"^ an L 3 x 10"^ from A, B[a]A and
B[a]P, respectively, while corresponding rates for sediments from an
uncontaminated stream were 2.5 x
systems, and that larger
L3
x
10"^.
This study
in
acclimated
PAH
(4-
and
5-ring
compounds)
are
much more
breakdown.
resistant to
incubation experiments, Bossert and Bartha (1986) found that the
biodegradation rate rings
4 x 10"^ and
biodegradation proceeds more quickly
indicates that
In soil
10"^,
and
was
inversely affected by the
directly correlated with
compounds
PHEN and ACEY) were
(A,
four to 16 months, while
most
16 months of incubation. exception; this of the 5-ring
water
study, 3-ring
is
5-ring
PAH remained
quite water soluble after
after
was an
Two
16 months.
compounds, PER and 1,2,5,6-dibenzoanthracene, showed after
16 months.
While most studies of
PAH
degradation
order kinetics could be used to describe et
and
compound was 97% decomposed
no degradation
Bulman
In this
solubility.
of aromatic
mostly or entirely degraded over
of the 4-
P which
number
al.
in soil
have assumed
PAH disappearance
(1985) found that either a model other than
that
from
first
first
soils,
order, or
5-27
a combination of two different models of
99%
of
PAH
was
required to describe
from previously uncontaminated
soil.
disappeared rapidly over 200 days or less
initially
PHEN,
until
94
occurred, and rate constants for removal were about the
5 and 50
PAH was
mg kg'^
concentrations for
Following the
initial
For B[a]A,
days, and only
loss, the
CHR
one
'free'
and B[a]P, only 22
was
concentration. Zero order kinetics of
CHR
of
first
compound
in
both
Loss
A.
of
particulates since
lost at
much
a
88% was degraded
identified for
slower
over 400
each compound and
was appropriate for describing the loss
and B[a]P, leading the authors
order kinetics
to
for
loss
available for analysis.
6% was
remaining 2 to
kinetic stage
soil
98%
same
loss
P and F
A,
to
compounds except
probably due to complexation with
adsorbed fractions reduced the
rate.
all
ttie
to
conclude that the assumption
modelling biodegradation of these
compounds Table 5-6
could seriously underestimate their persistence
in
summarizes the
reported by Bulman
et
al.
half-lives for
biodegradation
in soil
soil.
(1985), along with comparative degradation half-lives compiled from
Sims and Overcash (1983).
Sims and Overcash (1983)
PAH
biodegradation.
moisture
content,
listed several factors that affect
These include temperature, pH,
PAH
concentration
and
the rate of
soil
previous
aeration,
exposure.
Degradation tends to increase under conditions ideal for microbial Degradation rate
is
activity.
generally greater at higher concentrations, and
enhanced by previous exposure
to the
PAH.
is
5-28
TABLE
A Comparison
5-6
Half-Lives Calculated on the Basis of Rrst or Zero Order Models from Data Collected by Bulman et al. (1985) with those Reviewed by Sims and Overcash (1983)
PAH
5-29
5.2.2
Sorption
Aqueous concentrations soils
compounds such as PAH
of hydropliobic
and sediments depend on adsorptive/desorptive
sorbents
particles)
(solid
within
the systems.
equilibria with liquid-solid
soils,
In
in
partitioning plays a significant role in retarding the migration of
PAH
in
groundwater.
Adsorption
may
also play a role
PAH
in
degradation through surface-
associated chemical and biological processes (McCartyetal., 1981). The affinity of all
PAH
for soil particles
is
high,
and PAH-sorbent associations
are thought to occur primarily through van der Waals forces (Lyman et a!.,
1982).
The Freundlich adsorption model has been adsorption characteristics of
model
is
PAH
in
generally applied
in
evaluating
soil/sediment-water systems. This
presented as follows:
X/M = mass
X
where:
of
=
KC
1/n
compound adsorbed from
a given
mass
of
solution (ug);
M
= mass
C
=
of solid
adsorbent
(g);
equilibria concentration in the liquid
phase (ug/L); and
K,n = empirical constants.
K
is
a measure of adsorption strength or capacity and
of intensity, (n
=
1),
When
or
n =
i.e.,
a
is
an indicator
whether adsorption remains proportional to concentration
changes 1,
^'^
with changing adsorbate concentration
linear
isotherm results and:
(1
^n
c
to
^ E 4 > 5 rings.
In
al.
surface sediments.
in
and was found
only,
et
(1985).
al.
in
less than
activated sludge
1%
of
is
solids
on degradation
controversy
in
microorganisms
the water
in
in
to
was
column
sediments
investigated by Freitag
CO2 was 0.3% and 39.6%
to
and
5-ring
PAH
rates.
Degradation was
A
CO2.
Hall et
ACE
for
(B[a]P, Per, B[a]A
the literature concerning the effect of
microbial degradation of present.
PAH
of the 4-
and DB[a,h]A) were mineralized
There
rapidly
that
B[a]P mineralization was tested
The conversion
and Phen, but
> 3 >
1
water and sediments from
showed
PAH
the order
in
related
be minimal.
to
PAH
Biodegradation of
oil in
(1985) also
have the potential to degrade smaller
and
decreasing
an experiment using
the North Sea, Massie et
compound were
suspended
(1986) found that no significant
al.
occurred when no suspended solids were
more
significantly
rapid
in
the
highest
concentration of one suspended sediment sample tested over the next
lowest concentration after seven days.
sample
of
suspended sediment
degradation of of the
A
naturally occurring
It
suspended
the presence of a different
with a higher organic content, significant
also occurred, but
suspended sediment.
In
was
not related to the concentration
should be noted that the behaviour of solids
may be
different
from that of
experimentally re-suspended sediments.
Herbes
biodegradable particles
PAH
in
suggested that the
(1981)
and
in
sediments due to
resultant
reduced
water and sediment
in
larger
their
availability.
5-ring
PAH were
less
strong sorption to sediment
Comparative
a stream are presented
in
half-lives of six
Table 5-19.
5-62
TABLE
5-19
Degradation Rate Constants (k) and Half-Lives (t 1/2) for Mixed Bacterial Populations in Water and Sediment from the Same Stream
5-63
Other studies of biodegradation while biodegradation
metabolism
and sediments
in soils
does occur
in
dependent on many environmental factors as
is
shown
that
the aquatic environment, the rate of
composition of the microbial community and the
5.3.4
tiave
PAH
well as the
composition.
Microcosm Studies
The
intentional contamination of artificial
has been widely practiced fate.
in
Microcosm studies
of
ecosystems, or microcosms,
studies of contaminant transport and
some PAH have been conducted
compound and
determine the fate of each
various environmental compartments and
Fluorene
was
applied to experimental
trations of 0.12 to
mg/L
10.0
concentrations above the the
pond
surface.
limit
the 0.12-mg/L
was accounted
pond was
(Landrum to
1984).
appeared
at
concen-
Fluorene at
to sublime
from
well as sedimentation
for (7 to
and
only a small fraction of
18%). The
Fin
half-life of
in
6.7 days, while at the highest application
Anthracene added to an
photolyzed
al.,
after treatment,
concentration (10.0 mg/L) the
disappeared
(Boyle et
and sublimation as
Seven days
applied fluorene
fate.
Fluorene disappearance was rapid and attributed
largely to evaporation
degradation.
the relative importance of
pond ecosystems
of solubility
to
et
half-life
artificial al.,
anthraquinone
was 27.4 days.
stream microcosm also rapidly
1984). (half-life
subsequently rapidly photolyzed.
Anthracene was
43
minutes)
rapidly
which
was
The organic sediment acted as a
major repository, absorbing 0.2% of the 14-day input dose. Periphyton took up 0.04% of the applied dose, and
and
biota) contained relatively
all
other compartments (water
minor amounts.
5-64
Another channel experiment with anthracene provided (Bowling et
al.,
1984). Anthracene
was
input at 15
36 days. Downstream dissipation was rapid
for
daylight.
Some
achieved
maximum
loss
was
attributed
A
ug/L continuously
via photolysis, during
volatilization.
Aufwuchs
concentrations within 4 days (BCF = 1260) but the
concentration relative to the discontinuing
to
similar results
total
input
was
only 0.02%.
After
background concentrations were achieved
input,
in
water and aufwuchs within 24 hours and 72 hours, respectively.
In
a closed model aquatic ecosystem, B[a]P was applied to water
0.002
mg/L
days
in
(Lu et
al.,
1977). Bioaccumulation
organisms from several trophic
was observed
BCFs
levels.
at
for three
for fish, alga,
mosquito, snail and daphnia were 930, 5,258, 11,536, 82,231 and
134,248 respectively.
was introduced
Labelled B[a]A
to a large-scale
marine microcosm
resembling shallow coastal waters of the northeastern U.S. (Hinga a!.,
1980).
All
water with a
B[a]A and breakdown products were removed from the
half-life of
to sediments.
et
Some
plankton with an
Most B[a]A was
52 hours. ^""C activity
initial half-life
of
was observed
35 hours.
After
rapidly transferred in
particulates
230 days,
29%
and
of the
applied radioactivity had been respired to COj, while the remaining activity
was evenly divided between parent compound and intermediate
metabolic products.
6-1
6.0
ENVIRONMENTAL LEVELS AND SOURCE CONTRIBUTIONS The purpose
of this chapter
is
to integrate information from several
chapters to describe typical concentrations of in
Ontario
media through which environmental exposure
in
Emission
occur.
profiles
and emission rates are used
relative contributions of selected
loading of
PAH
assessment
6.1
Levels
air
Ontario.
in
to
PAH may
to estimate the
source categories to the atmospheric
Finally,
summary conclusions
regarding an
of the information contained in the report are offered.
in Air, Soil
Ambient
PAH which may be found
PAH
and Water
levels
near the Niagara River were measured
in
a study
by the Atmospheric Environment Service (Hoff and Chan, 1987).
samples were collected Sampling
were
sites
at
three
(3)
sites
during
Hi-vol
1982 and 1983.
at the following locations:
Niagara-on-the-Lake; Fort Erie;
Niagara
and
Falls.
The sampling
configuration
(PUF) plug.
The two
vapour portions.
was a
Because
of
may be
The sum
two fractions
Average
particulate
are summarized
in
followed by a polyurethane foam
fractions represent nominally, the particle
particle fraction
of the
filter
blow
off
and
volatilization
processes, the
distorted for intermediate molecular weight is
and
PAH.
more accurate.
and gaseous PAH concentrations from the three Tables 6-1 and 6-2
for tests
1982 and January 1983 respectively. The
conducted
results
in
showed a
sites
September
strong, local
6-2
PAH
influence of heavier weight particulate
from the winter sampling
period (January, 1983).
For example, Erie,
lower
at
in
ambient
Niagara
air,
Falls
the
An examination
of
concentration
and lowest
directly related to the inputs
1987).
PAH
at
was highest
at Fort
Niagara-on-the Lake, which
from industry and mobile sources
is
(Hoff,
wind flow direction during the sampling period
PAH
indicated a strong influence on the
the urban areas of Buffalo, Niagara
level arising
Falls,
from emissions from
NY, and Niagara
PAH
for easterly winds. In addition, the increase in
Ontario,
Falls,
emissions
Niagara-
at
on-the-Lake for north northwesterly winds was possibly due to transport
from the Toronto-Hamilton urban corridor.
Ontario Ministry of the Environment annual
1973 to 1983
at the
with results of the
A
definitive
study
distribution in the
Niagara
AES
was
PAH
results for the period
along
Falls sites are illustrated in Figure 6-1
study (Hoff and Chan, 1987).
carried out by Katz et
ambient
four
air of
Two
Hamilton, Sarnia and Sudbury.
(4)
al.,
Ontario
sites in
1978, on the cities,
PAH
Toronto,
i.e.,
Toronto were reported.
Selected results from the various sampling sites are summarized
in
Tables
6-3 and 6-4.
The study shows site,
that the highest
PAH
levels
occurred
at the
followed by Toronto, Sarnia and Sudbury. B[ghi]PER
at significant levels at
all
the sites.
The
likely
be from the exhaust gases
of
motor vehicles.
A
air
PAH has
recent survey of ambient
from 1984-1986 (Dann, 1988).
also
Hamilton
was reported
source was postulated to
been carried out
Data are presented
in
in
Toronto
Table 6-5.
6-3
TABLE
Mean Ambient
6-1
Air Levels of Polycyclic
Aromatic Hydrocarbons at Niagara-on-the-Lake, Niagara Falls and Fort Erie in September, 1982
Compound
6-4
TABLE Mean Ambient
6-2
Air Levels of Polycyclic
Aromatic Hydrocarbons Near Niagara-on-the-Lake, Niagara Falls and Fort Erie in January, 1983
6-5
FIGURE
6-1
Graphical Illustration of Benzo[a]pyrene Concentration and Year of Study at
Chippewa/Niagara Falls the Particulate Phase
in
10,000
BENZO[a]PYRENE
1,000
n E
I z o F < 100 UJ
o z o o
10
•
A
CHIPPAWA (MOE) HOFF AND CHAN, NIAGARA
_L 73
_L 74
_L 75
_L 76
_L 77
78
YEAR
From: Hoff and Chan, 1987.
_L 79
_L 80
_L
81
82
FALLS
_L 83
1987
(MOE)
6-6
CO
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^ ^
Q.
3 CO
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3
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