Polycyclic aromatic hydrocarbons in the urban ... - ScienceDirect

Atmospheric Environment 33 (1999) 3731}3738

Polycyclic aromatic hydrocarbons in the urban atmospheric particulate matter in the city of Naples (Italy) Anna Maria Caricchia*, Salvatore Chiavarini, Massimo Pezza Environmental Analysis and Monitoring Department, ENEA, C.R. Casaccia, via Anguillarese 301, 00060 Rome, Italy Received 18 September 1998; accepted 23 March 1999

Abstract An investigation on PAH in the atmospheric particulate matter of the city of Naples has been carried out. Urban atmospheric particulate matter was sampled in three sampling sites (West, East and central areas of the city), whose characteristics were representative of the prevailing conditions. In each site, 24 h samplings for 7 consecutive days were performed during three sampling campaigns, in 1996}1997. The results were comparable with those reported in literature for similar investigations. Total PAH were in the range 2}130 ng m\, with a seasonal variation (autumn/winter vs. summer) in the range 1.5}4.5. The relative contribution of diesel engines vs. gasoline fuelled engines was evidenced. 1999 Elsevier Science Ltd. All rights reserved. Keywords: Polycyclic aromatic hydrocarbons; Particulate matter; Ambient air; Urban; Naples

1. Introduction Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants and some of them are among the strongest known carcinogens (IARC, 1984). It is a well-known fact that atmospheric PAH are partitioned between particulate matter and the gas phase. The recognized carcinogenic PAH are mostly associated with particulate matter (Cautreels and Van Cawenberghe, 1978; Lyall et al., 1988). Atmospheric PAH concentrations are strongly dependent upon the size of airborne particulate matter, with the highest concentration being in the respirable size range: about 95% of total PAH is associated with a size class less than 3 lm in diameter (Baek et al., 1991a,b; Pistikopoulos et al., 1990; Venkataraman and Friedlander, 1994). It has been estimated that stationary sources contribute for approximately 90% of total PAH emission, but this is not true in urban and suburban areas, where the mobile sources are prevailing (Baek et al., 1991a; Harvok and Greenberg, 1985). The highest concentrations of

* Corresponding author. Fax: #39-06-30486678: e-mail address: [email protected].

atmospheric PAH can be found in the urban environment, due to the increasing vehicular tra$c and the scarce dispersion of the atmospheric pollutants. The risk associated with human exposure to atmospheric PAH is highest in the cities, considering the density of population. For these reasons, PAH have been included among the atmospheric pollutants (Italian Ministry Decree, 25 November 1994) in the Italian regulation. The Italian Ministry of Environment has promoted an investigation on PAH in the atmospheric particulate matter of the city of Naples. The work has been carried out by the Italian National Agency for New Technology, Energy and the Environment (ENEA) in the frame of a project to develop models for the estimation of benzene and PAH human exposure in urban areas. This paper reports the results of the investigation on PAH in particulate matter. The abbreviations, relative to PAH and to other compounds, used in this paper are the following: phenanthrene (PHE), anthracene (AN), #uoranthene (FA), pyrene (PY), benzo(b)naphtho(1,2-d)thiophene (BNT), cyclopenta(cd)pyrene (CPP), benz(a)anthracene (BaA), chrysene (CHR), sum of benzo(b), benzo(j) and benzo(k) #uoranthene (BbF#BjF#BkF), benzo(a)pyrene (BaP),

1352-2310/99/$ - see front matter 1999 Elsevier Science Ltd. All rights reserved. PII: S 1 3 5 2 - 2 3 1 0 ( 9 9 ) 0 0 1 9 9 - 5

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A.M. Caricchia et al. / Atmospheric Environment 33 (1999) 3731}3738

benzo(e)pyrene (BeP), indeno(1,2,3-cd)pyrene (IP), dibenz (ah)anthracene (DBahA), benzo(ghi)perylene (BghiP) and coronene (COR).

2. Experimental 2.1. Sampling Naples has an extremely complex urban layout, therefore no attempt was made to fully characterize each local situation. Urban atmospheric particulate matter was

sampled in three sampling sites (Fig. 1) whose characteristics were representative of the prevailing conditions. Site 1 is in the central part of the city, in a residential area characterized by a high tra$c density and narrow streets #anked by buildings. Site 2 is located in the west side of the city in a relatively open area characterized by a slow and dense incoming tra$c. Site 3 is in a peripheral industrial area located in the east side of the city crossed by a thoroughfare and very close to a ring-road. 24 h samplings for 7 consecutive days were performed during three sampling campaigns. The periods of the three campaigns were: 24 September 1996}30 September

Fig. 1. Map of Naples showing the position of sampling sites.


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1996, 26 February 1997}04 March 1997 and 25 June 1997}01 July 1997, respectively, for I, II and III campaign. After each 24 h sampling, the "lter was removed from the pump, folded with the adsorbed particulate matter on the inner side, wrapped in an aluminium foil, stored at 43C and analysed within 15 days from collection.

BbF#BjF#BkF, BaP, BeP, IP, DBahA, BghiP and COR. The mean recovery is about 75% with a CV% of 15% and the mean determination limit is 0.01 ng m\.

2.2. Materials

Analytical data are reported in Tables 1}3 for Site 1, 2 and 3, respectively. The weekly median and average value for each compound, with the minimum and maximum values and the total PAH concentrations (sum of the single analysed compounds) are reported in these tables. For data below the detection limit, the value of detection limit itself (0.01 ng m\) has been used to calculate the average, the median and total concentrations. All values relative to each 24 h sampling are available. The investigation of potential PAH losses upon "lter collection was outside the scope of this work. Such losses can be considered negligible for most of the determined PAH under the adopted sampling conditions. In fact, a literature survey shows that losses of PAH from particulate collected on "lters are signi"cant only for long sampling periods ('24 h) and only for PAH containing less than "ve rings. The in#uence of the common air pollutants as SO , No , O , generally present in urban V V air, is evident only after long collection periods (Caricchia et al., 1995). Based on these evidences, the concentrations reported in the previous tables are a good estimation of the environmental levels, except for the most volatile PAH such as PHE and AN. Nevertheless, PHE and AN were included in all the tables, "gures and subsequent considerations, as this does not signi"cantly a!ect the results, still providing more useful data. Concentrations of individual compounds are in the range 0.01}20 ng m\. The total PAH are in the range of 2}130 ng m\. These values are similar to those generally found in the atmospheric urban particulate matter in Italy, Europe and other locations worldwide (Caricchia et al., 1992; Cecinato et al., 1998; Menichini and Rossi, 1991; Menichini, 1992; Menzie et al., 1992; Pala et al., 1996; Rossi et al., 1995). Data relative to the summer campaign (III) are lower than those relative to the autumn and winter campaigns, in all the three sites (Tables 1}3). The ratios of autumn and winter to summer total PAH are in the range 1.5}4.5. This is in accordance with results reported in literature: winter levels, as stated in several investigations carried out in Europe and in the USA, are generally higher by a factor of 2}10 (Baek et al., 1991a; Greenberg et al., 1985; Harrison et al., 1996; Menichini, 1992; Smith and Harrison, 1996). The higher urban PAH in winter with respect to warmer seasons are due to the contribution of domestic heating and to the di!erent meteorological conditions that, during summer, cause PAH photodegradation and an easier atmospheric dispersion of pollutants.

Organic solvents (RS, for pesticide residues analysis) were purchased from Carlo Erba (Milano, Italy). PAH standards were purchased from Supelco (Bellefonte, PA, USA). Anhydrous sodium sulphate, RG, was obtained from Rudi-Pont (Milano, Italy). Silica gel 60, 70}230 mesh (activated at 1803C for 24 h and stored in a closed vessel) was obtained from Merck (Hohenbrunn, Germany). Samplings were performed by three high volume pumps (1.13 m min\), Model 1200 by Sierra-Andersen equipped with PM10 size-selective inlets. Atmospheric particulate matter ((10 lm diameter) were sampled on glass "bre "lters (20;25 cm). GC/MS analyses were performed on a HewlettPackard 5890 GC/HP 5970B MSD system with the following conditions: electron impact ionization mode (70 eV); carrier gas: He; column: ULTRA 2 (methyl5%phenylsilicone, 0.20 mm i.d., 0.11 lm "lm thickness, 25 m length, from Hewlett-Packard); temperature program: 803C;2 min, then 203C min\}1803C, hold 1 min, then 33C min\} 2803C; injector: splitless, 2603C; transfer line temperature: 2803C; selected ion monitoring (SIM) operation. 2.3. Analysis The analytical procedure used in this study is reported in a previous work (Caricchia et al., 1995). Toluene was used instead of benzene/methanol, because of its lower toxicity and higher recoveries, especially for higher boiling PAH (Jacob, 1995). A Soxhlet extraction of "lters in toluene for 16 h was performed (400 ng of anthracene-D10, chrysene-D12 and perylene-D12 as procedure internal standards were added before the extraction). The extract was evaporated to a small volume (about 5 ml) in a rotating evaporator and then nearly to dryness under a moderate #ow of nitrogen, before it was taken up to 1 ml with hexane. The sample extract was then puri"ed and fractionated by silica gel (3 g) column (i.d. 0.6 cm) chromatography eluting with 10 ml hexane (aliphatic hydrocarbons) and then with 20 ml of hexane : toluene 1 : 1 (PAH). The fraction containing PAH, added with benz(a)anthracene-D12 as determination internal standard, was analysed by GC/MS. The concentrations of the following compounds were determined: PHE, AN, FA, PY, BNT, CPP, BaA, CHR,

3. Results and discussion

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Table 1 Site 1. Median (Med), average (Avg), minimum (Min) and maximum (Max) values of the compounds concentrations (ng m\) in the urban atmospheric particulate

PHE AN FA PY BNT CPP BaA CRY B(b#j#k)F BeP BaP IP DBahA BghiP COR Total

I Sampling 24 September 1996}30 September 1996

II Sampling 26 February 1997}04 March 1997

III Sampling 25 June 1997}01 July 1997

Med

Max

Med

Avg

Min

Avg

Min

Max

Med

Avg

Min

Max

0.97 0.15 0.71 1.15 0.06 0.03 0.76 1.44 5.23 5.74 0.94 3.85 0.26 9.09 5.32

0.93 0.14 0.74 1.21 0.07 0.39 0.93 1.40 5.47 5.57 1.43 3.75 0.25 8.91 5.53

0.34 0.05 0.33 0.50 0.02 0.01 0.27 0.49 1.68 1.92 0.31 1.29 0.09 2.91 1.76

1.52 0.18 1.11 1.98 0.12 1.35 1.91 2.43 8.81 8.10 3.80 5.49 0.34 13.98 9.85

0.55 0.10 1.15 1.66 0.07 0.25 0.99 1.86 3.57 4.03 1.14 2.57 0.17 5.79 3.45

0.51 0.10 1.03 1.54 0.07 0.34 0.91 1.58 3.11 3.30 1.08 2.12 0.16 4.66 2.79

0.23 0.05 0.19 0.28 0.02 0.01 0.12 0.26 0.81 0.89 0.09 0.55 0.03 1.17 0.92

0.88 0.13 1.71 2.53 0.11 1.12 1.53 2.25 4.17 4.75 1.80 2.90 0.22 6.66 3.87

0.13 0.04 0.18 0.25 0.02 0.01 0.18 0.43 1.18 1.22 0.14 0.85 0.07 1.87 1.44

0.14 0.04 0.16 0.22 0.02 0.03 0.14 0.34 1.08 1.21 0.20 0.92 0.07 1.97 1.65

0.06 0.02 0.06 0.07 0.01 0.01 0.03 0.11 0.27 0.27 0.03 0.19 0.01 0.40 0.29

0.23 0.06 0.25 0.37 0.03 0.13 0.22 0.49 1.97 2.49 0.60 1.99 0.14 4.56 3.72

37.97

36.71

11.98

60.02

29.24

23.32

5.61

31.48

8.42

8.18

1.80

16.98

Table 2 Site 2. Median (Med), average (Avg), minimum (Min) and maximum (Max) values of the compounds concentrations (ng m\) in the urban atmospheric particulate I Sampling 24 September 1996}30 September 1996



Med

Avg

Max

Med

Med

PHE AN FA PY BNT CPP BaA CRY B(b#j#k)F BeP BaP IP DBahA BghiP COR

1.35 0.29 1.87 3.06 0.23 0.61 3.11 3.94 8.57 10.10 2.83 6.75 0.47 15.80 8.68

2.11 0.32 2.31 4.06 0.27 2.00 3.17 4.14 8.80 9.95 3.89 6.81 0.48 15.30 8.78

0.57 0.15 0.91 1.44 0.16 0.08 1.92 2.68 6.49 6.67 1.97 4.64 0.34 9.47 5.89

5.15 0.50 3.49 6.15 0.52 9.74 4.65 6.44 11.62 11.80 6.90 8.27 0.61 18.99 11.97

1.41 0.24 1.98 3.07 0.22 7.00 2.44 3.68 6.57 6.62 3.19 4.23 0.33 8.82 5.60

1.71 0.32 2.83 4.50 0.32 4.47 2.85 3.84 7.65 7.72 3.70 5.06 0.38 10.97 7.37

0.58 0.10 0.57 0.91 0.05 0.01 0.51 0.95 2.68 3.05 0.45 2.18 0.15 5.13 2.76

3.83 0.71 8.10 12.38 0.72 17.05 6.38 8.12 14.01 13.55 9.48 8.44 0.66 17.83 13.69

0.56 0.13 0.57 0.82 0.10 0.32 0.81 1.47 3.32 3.8 1.31 2.61 0.18 5.92 4.66

Total

69.42

72.41

44.79

99.02

49.17

63.70

20.27

131.31

25.94

Min

The limited temperature excursions found during this study (about 203C on a daily average basis), do not a!ect in a signi"cant way the distribution of PAH between the gas and particulate phases (Muller et al., 1998).

Avg

Min

Max

Avg

Min

Max

0.52 0.13 0.53 0.77 0.09 0.42 0.71 1.22 3.36 3.91 1.33 2.83 0.19 6.71 5.51

0.20 0.03 0.25 0.37 0.04 0.01 0.29 0.52 1.09 1.25 0.19 0.82 0.05 2.01 1.43

0.76 0.21 0.72 1.06 0.13 0.82 1.06 1.67 6.05 7.38 2.87 5.59 0.36 13.7 11.83

28.23

8.67

54.03

Italian regulation (Italian Ministry Decree, 25 November 1994) indicates the following toxic PAH for monitoring purposes: BaA, BbF, BjF, BkF, BaP, IP, DBahA. Their trend is very close to the total PAH one.


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Table 3 Site 3. Median (Med), average (Avg), minimum (Min) and maximum (Max) values of the compounds concentrations (ng m\) in the urban atmospheric particulate

PHE AN FA PY BNT CPP BaA CRY B(b#j#k)F BeP BaP IP DBahA BghiP COR Total

I Sampling 24 September 1996}30 September 1996



Med

Max

Med

Med

Avg

Min

Avg

Min

Max

Avg

Min

Max

0.93 0.09 0.83 1.11 0.04 0.01 1.59 3.24 7.78 6.10 1.53 4.45 0.46 5.68 2.21

0.96 0.09 0.87 1.17 0.04 0.02 1.34 2.67 7.98 5.95 1.38 4.32 0.47 5.65 2.25

0.45 0.05 0.25 0.32 0.02 0.01 0.44 1.15 3.64 2.97 0.41 2.18 0.21 2.91 1.26

1.68 0.16 1.57 2.12 0.06 0.05 2.04 3.83 12.80 8.34 2.14 6.18 0.78 7.69 3.19

1.22 0.22 1.18 1.38 0.20 5.98 1.90 4.19 7.52 5.22 3.13 3.80 0.46 4.51 2.26

1.14 0.19 3.68 5.07 0.20 4.63 3.17 5.21 8.96 6.59 5.13 4.76 0.50 6.49 3.69

0.34 0.06 0.21 0.24 0.01 0.01 0.13 0.30 0.99 0.77 0.09 0.53 0.05 0.82 0.41

2.13 0.32 9.93 12.96 0.51 19.94 8.01 12.75 20.06 13.84 12.28 10.25 1.20 13.39 8.85

0.30 0.09 0.61 0.81 0.01 0.01 0.76 1.56 5.99 4.11 1.23 3.37 0.42 3.61 1.67

0.32 0.17 0.86 1.12 0.02 0.39 0.96 1.78 4.73 3.38 1.75 2.93 0.34 3.31 1.86

0.10 0.04 0.16 0.20 0.01 0.01 0.10 0.23 0.66 0.53 0.09 0.45 0.04 0.69 0.41

0.54 0.66 1.78 2.37 0.04 1.38 2.11 3.34 7.93 5.79 4.02 5.11 0.60 5.72 3.54

37.13

35.14

17.56

50.14

36.35

59.40

5.30

130.46

28.89

23.90

3.70

41.48

Fig. 2. Benzo(a)pyrene distribution.

Daily levels of BaP, the most investigated PAH and often used as an indicator of total PAH, are in the range 0.03}12.00 ng m\. These values are similar to those generally found in the Italian and European urban areas (Harrison et al., 1996; Pala et al., 1996). 5% only of all measurements exceeded 2.5 ng m\ in Site 1 (Fig. 2). Site 2 shows higher levels: about 50% are in the range 1.0}5.0 ng m\ with 20% '5 ng m\. About 50% of

the BaP levels in Site 3 are in the range 1.0}5.0 ng m\ with about 40% (1 ng m\. Nevertheless, site 3 also shows the highest concentrations found in the whole investigation: these are referred to late winter weekend days with a likely huge car tra$c at the entrance of the city, also present in site 2, with site 1 (city centre) mostly una!ected. Besides the reduced number of samples and sampling sites, we believe that the concentrations of BaP

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determined in this study can be considered a valid estimate of the average situation. The average levels of BaP over the three sampling campaigns are 0.90, 2.97 and 2.82 ng m\ in sites 1, 2 and 3, respectively. In comparison with the annual average value of 1 ng m\ (from 01 January 1999) that the Italian regulation indicates as

quality objectives, BaP levels in sites 2 and 3 exceed the limit. The concentrations of some marker compounds and their ratios can give some indication about the impact of di!erent sources of airborne compounds, even if this matter is still widely debated (Kang Li and Kamens,

Fig. 3. Pro"le of PAH (weekly average).


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Fig. 4. IP/BghiP ratio.

1993; Pistikopoulos et al., 1990; Touminen et al., 1988). In the urban environment marker compounds are often used to indicate the prevalence of diesel or gasoline engines, as well as the relative contribution of tra$c, domestic heating and other urban sources. The weekly average pro"les of PAH are shown in Fig. 3. Sites 1 and 2 show very similar pro"les, suggesting the presence of similar predominant seasonal sources and atmospheric reactivity of PAH. Site 3 is subjected to a greater variability. BghiP and COR, that derived almost exclusively from motor vehicles (Freeman and Cattell, 1990; Nielsen, 1988), are always present at elevated concentrations (BghiP average levels are in the range 2}15 ng m\). CPP and BNT, that are considered good markers for gasoline fuelled and diesel engines, respectively, are also present, but their concentrations are very low and close to the detection limits. Because of the high uncertainty in their concentrations, the CPP/BNT ratio, which is usually diagnostic for assessing the prevalence of one of the two sources (Caricchia et al., 1992), could not be used reliably in this work. Safer indications come from the IP/BghiP ratio. IP/BghiP ratios of about 0.4 are typical of gasoline engines, while for diesel engines this value approaches 1. In this study, the IP/BghiP ratio is in the range 0.42}0.47 for sites 1 and 2 during all the three sampling campaigns, while site 3 has higher values, in the range 0.73}0.76, clearly showing a prevalent contribution of diesel engines (Fig. 4). The absolute concentrations of BghiP and COR, that are characteristic of gasoline engines as above mentioned, con"rm this "nding: the sum of BghiP and COR concentrations with respect to the total PAH is in the range 31}42% in sites 1 and 2 and from 19 to 23% in site 3.

4. Conclusions The PAH concentrations in the atmospheric particulate matter of the city of Naples, as found in this study, are aligned with the mean urban situation in Italy. Seasonal e!ects were evidenced and found to be in accordance to similar investigations reported in literature. BaP and other toxic PAH concentrations are still a matter of concern, particularly, with respect to the quality objectives set forth in the Italian Legislation. The diesel engines contribution to the PAH concentrations is much higher in site 3 than in sites 1 and 2, owing to the industrial characteristics of the investigated area.

Acknowledgements We greatly thank Dr. S. Merolli (ENEA) and his coworkers as project leader. Support for this work from the Environmental O$ce of the Naples Municipality is deeply acknowledged.

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