Measurements of Polycyclic Aromatic Hydrocarbon Adsorption on Activated Carbons at Very Low Concentrations

Atmospheric Environment 37 (2003) 3009–3018

Measurements of polycyclic aromatic hydrocarbonsin airborne particles from the metropolitan area of

S*ao Paulo City, Brazil

P!erola C. Vasconcellosa, Davi Zacariasa, Maria A.F. Piresa,Cristina S. Poolb, Lilian R.F. Carvalhob,*

a Instituto de Pesquisas Energ!eticas e Nucleares SP, Brazilb Instituto de Qu!ımica, Universidade de S *ao Paulo, Cx.P. 26077, 05599-970 S *aoPaulo, SP, Brazil

Received 18 September 2002; received in revised form 27 January 2003; accepted 21 February 2003

Abstract

Polycyclic aromatic hydrocarbons (PAHs) from phenanthrene to benzo[g,h,i]perylene in airborne particles were

measured in the winter of 2000 at three different sites within the metropolitan area of S*ao Paulo City (MASP), Brazil. It

is one of the largest metropolitan areas in the world and has an unconventional mixture of vehicle types, in which a

variety of gasoline blends, including oxygenated ones, are used. In this study, occurrence of PAH, meteorological

conditions and inter and intrasite comparisons are presented. Overall, the results revealed low PAH levels due to

rainfall episodes during the sampling period. Samples collected in the urban site presented the highest PAH

concentrations (av. 3.10 ngm�3) when compared to those collected in the urban site with dense vegetation (av.

2.73 ngm�3) and in the forest area (av. 1.92 ngm�3). PAH measurements in tunnels with different types of vehicles were

performed in order to suggest possible tracers of the vehicular emissions in S*ao Paulo. Pyrene followed by chrysene and

fluoranthene were emitted mainly from gasohol vehicular motor exhausts, whereas chrysene, pyrene and

benzo[a]anthracene were emitted mainly from gasohol and diesel vehicular motor exhausts. Some characteristic ratios

from the tunnel measurements were used to identify vehicular sources in the atmosphere of the MASP. Although it is

known that losses can occur both by evaporation and sublimation during sampling, measurements of higher molecular

weight PAH compounds were taken into consideration due to their high recovery efficiency.

r 2003 Elsevier Science Ltd. All rights reserved.

Keywords: PAH; Airborne particles; Tunnel measurements; S*ao Paulo City

1. Introduction

Polycyclic aromatic hydrocarbons (PAHs) are by-

products of the incomplete combustion of organic

matter. They are of major health concern, mainly due

to their well-known carcinogenic and mutagenic proper-

ties (Junker et al., 2000).

Anthropogenic emission sources for PAH in the

atmosphere include tobacco smoke, motor vehicles,

waste incineration, domestic heating, oil refining,

and other industrial processes. Besides, an important

natural source is the biomass burning that occurs in

forest fires (Masclet et al., 1995; Cecinato et al., 1997;

Vasconcellos et al., 1998; Oros and Simoneit, 2001).

Nonetheless, in urban areas, vehicular exhaust has

been considered the most predominant emission

source. As PAHs associated to airborne particles cha-

nge significantly with their emission sources, some

PAH concentration ratios have been used to propose

possible vehicular emission sources (Venkataraman

et al., 1994).

ARTICLE IN PRESS

AE International – Central & South America

*Corresponding author Fax: 11-3091-3837.

E-mail address: [email protected] (L.R.F. Carvalho).

1352-2310/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved.

doi:10.1016/S1352-2310(03)00181-X

To help identify the major emission sources respon-

sible for adverse health effects, a comprehensive survey

of atmospheric contaminants from a variety of sources

has been performed worldwide. Urban measurements of

the atmospheric PAHs in several cities from industria-

lized countries have been reported (Panther et al., 1999;

Halsall et al., 2001; Schnelle-Kreis et al., 2001), but few

experiments have been performed in the main Brazilian

cities (De Martinis et al., 2002; Azevedo et al., 2002;

Fernandes et al., 2002; Santos et al., 2002). To evaluate

the chemical profile of a major urban center with serious

air pollution problems, PAH compounds were analyzed

on atmospheric particulate matter collected from a

major South American city, S*ao Paulo, Brazil, whose

population of approximately 17 million is exposed

primarily to industrial and motor vehicle emissions.

The urban area of S*ao Paulo City has an unconven-

tional mixture of vehicle types, in which a variety of

gasoline blends, including oxygenated ones, are used.

This paper reports measurements of PAH associated

with atmospheric particulate matter collected in three

different sampling sites located inside the metropolitan

area of S*ao Paulo (MASP). The results reported here

form part of a larger study on air pollution and

meteorology in S*ao Paulo City. Occurrence of PAH,

meteorological conditions and inter and intrasite com-

parisons are presented. PAH measurements in tunnels

with different types of vehicles were used to propose

possible tracers of vehicular emissions in S*ao Paulo.

2. Experimental

2.1. Sampling procedure

Total suspended particles (size smaller than 200mm)were collected using a high-volume air sampler. Samples

were collected for 24-h periods. Quartz fiber filters

(20� 25 cm2) were pre-cleaned by heating in oven at

800�C for 8 h. After sampling, filters were wrapped in

aluminum foil and stored in a freezer at �20�C, untilthey were weighted and extracted.

2.2. Sampling sites characteristics

S*ao Paulo is the largest industrialized region in Latin

America. Currently, there are approximately 6.5 million

automotive vehicles: 390,000 heavy-duty diesel (HD),

and 5.5 million light-duty (LD) vehicles. Approximately

4.2 million of the light-duty cars are fueled with a

mixture containing 78–80% (v/v) gasoline, 20–22%

ethanol, which is referred to as gasohol and 1.1 million

are fueled with ethanol. From 1996 to 1999, there was an

increase in the number of cars with gasohol (25%), while

the number of cars fueled with ethanol remained at the

previous level (Montero et al., 2001).

In this work, three sampling sites within the MASP

(Fig. 1) were chosen on the basis of local differences in

the type, distribution, and proximity of emission

sources, as well as differences in the wind direction

frequencies. Two of them, B15 km distant from each

other, are located in urban areas and the third is a forest

region,B50 km distant from the nearest urban sampling

site.

The !Agua Funda (AF) site, located in the southeast

side of the city, is a large area with abundant vegetation.

It is one of the last remaining parts of the Mata

Atl#antica forest. The area receives minimal impact from

local anthropogenic sources. There are no industrial and

commercial operations in the immediate vicinity, but

B20 km southeast is the largest Latin-American indus-

trial park, Cubat*ao, with several emission sources,

including petrochemical and oil refinery areas. The

atmospheric air collections in the AF site were

performed in an open area at ground level.

The Cidade Universit!aria (CID) site, southwest of S*ao

Paulo, is an area that can be considered potentially

impacted by various types of sources. The sampling site

is B2 km far from a major highway with frequent

vehicle traffic fueled by gasohol, diesel, and ethanol. At

this site, the sampler was placed in an open area on the

roof of the Department of Atmospheric Sciences,

located on the main campus of the University of S*ao

Paulo, B20m above ground level.

The Cotia (COT) site is a forest area of 10,700

hectares named Reserva do Morro Grande, which

comprises rich reminiscent Mata Atl#antica vegetation,

still preserved with a great diversity of fauna and flora.

This forest area is located in Cotia, an adjacent

municipality of S*ao Paulo City, west of the metropolitan

area. The sampling site is approximately 15 km far from

a major highway with a heavy vehicle traffic fueled by

diesel. The atmospheric air collections in the COT site

were performed in an open area at ground level.

ARTICLE IN PRESS

Fig. 1. Map of the metropolitan area of S*ao Paulo showing

sampling sites.

P.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–30183010

Atmospheric particulate matter was collected during

the winter of 2000 in two sites simultaneously, at each

time period. Experiments were performed on consecu-

tive days from 9 August to 4 September in the AF site,

with a total of 22 samples. Samples of the COT site

(n ¼ 11) were collected from 9 August to 17 August,

while samples of the CID site (n ¼ 14) from 18 August

to 3 September (total samples taken=48, total samples

analyzed=41).

Two-hour samples were collected at two roadway

tunnels with different types of vehicles. The sampling

location was about 200m inside the tunnel. The J#anio

Quadros Tunnel (JQT), near the CID site, where

emissions are from gasohol and ethanol fueled vehicles,

and the Maria Maluf Tunnel (MMT), very close to the

AF site, with gasohol, ethanol and diesel fueled vehicles.

Differences in the proportion of vehicle types in the

MMT and density of vehicles in the JQT were observed

at each sampling time studied (see Section 3.3). In the

MMT, there was an increase of HD vehicles at the

second sampling time, while the LD vehicles traffic was

practically constant during the whole sampling time. On

the other hand, the LD vehicle density in the JQT was

gradually increased at each sampling time from morning

to midday and midday to afternoon.

Tunnel sampling was performed on weekdays from

10 a.m. to 4 p.m. in the JQT (August 2001) and 8 a.m. to

12 p.m. in the MMT (October 2001). Average tempera-

tures of 24�C and 21�C and relative humidities of 76%

and 68% were recorded during the experiments in the

JQT and MMT, respectively.

2.3. Analytical procedures

Filters were weighed prior to use and after sampling

for mass determination of the total suspended particu-

late (TSP). A Soxhlet apparatus filled with methylene

chloride was used for extracting filters. The samples were

extracted for B20 h and a fractionation, as described in

detail by Ciccioli et al. (1996), was used to obtain the

PAH, nitro-PAH and oxygenated-PAH fractions. In this

work, only the PAH fraction is focused.

The PAHs were identified using a gas chromatograph

coupled to a mass spectrometry detector (Shimadzu

model GCMS-QP5000) and a NIST library, and gas

chromatography with flame ionization detection (Shi-

madzu model GC-17A) was used for quantification. The

detection mode used for identification was the single ion

monitoring (SIM). A 30-m fused-silica capillary column,

DB-5 (0.2mm ID, 0.25 mm film thickness), was used for

separation. The temperature program used is described

elsewhere (Ciccioli et al., 1996).

Recoveries of PAH were calculated using EPA 610

Polynuclear Aromatic Hydrocarbons Mix from Supelco

and determined by adding a known PAH standard

amount, in ng/ml, in a blank filter. The recovery and

limit of detection of the PAH compounds studied are

presented in Table 1. Concentrations of low molecular

weight PAH compounds were not considered in this

work, as their recoveries were very low (o50%). PAH

concentrations in laboratory and field blanks were

consistently very low and data was not subjected to

any blank correction.

The standard PAH mixture containing phenanthrene

(Phe), anthracene (Ant), fluoranthene (Fla), pyrene

(Pyr), benzo[a]anthracene (BaA), chrysene (Chr), ben-

zo[b]fluoranthene (BbF), benzo[j]fluoranthene (BjF),

benzo[a]pyrene (BaP), and indeno[1,2,3-cd]pyrene

(InP), dibenzo[a,h]anthracene (DBA) and benzo[g,h,i]-

perylene (BPe) was used for comparing retention time of

the peaks and for quantification as external standard.

For benzo[e]pyrene (BeP) identification, an individual

standard solution was used and quantification was

carried out using the BaP response factor.

2.4. Meteorological conditions

S*ao Paulo presents an upland tropical climate with

dry season during wintertime. In summer, monthly

average temperatures reach up to 23�C (from December

to February), whereas in winter, monthly temperatures

are around 16�C (from June to August). The rainy

season normally begins in September and ends in

March, with an annual precipitation around 1200mm.

The local circulation is given by southeast and northeast

winds, mainly associated with the Atlantic Ocean breeze.

In winter, there are often polar mass arrivals associated

with cold front systems that can intensify the circulation

coming from southeast. The latter may explain the

transport of pollutants from the southeast to the

northwest regions of the MASP during these events.

Thermal inversions can frequently occur associated to a

polar mass stagnation over the MASP. Before the onset

ARTICLE IN PRESS

Table 1

PAH recovery (%) and detection limit (mgml�1)

PAH Recovery, % (n ¼ 3) Detection limit,

(mgml�1)

Phe 63 0.6

Ant 52 0.6

Fla 92 0.5

Pyr 86 0.5

BaA 101 0.5

Chr 103 0.4

BbF 103 0.6

BjF 76 0.4

BaP 120 0.2

BeP 120 0.2

InP 115 0.6

DBA 109 0.7

BPe 96 0.1

P.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–3018 3011

of frontal systems, the wind blows from northwest

bringing dry and warmer air from continental areas,

which characterizes the air mass transport from these

regions (Montero et al., 2001).

Several rain episodes were observed during the

sampling period, which characterized atypical winter

days (av. temperature=18�C and av. relative humid-

ity=70%). In August 2000, total precipitation volume

was 70.4mm. AF samples from 15, 16, 27 and 28 August

and CID sample from 28 August were excluded from the

data set because of the rainfall events (other samples

were lost due to operational problems). Thermal

inversion episodes and sunshine conditions were re-

corded in this period. Temporal variations of tempera-

ture, relative humidity, wind velocity, solar radiation

and precipitation volume, in conjunction with the daily

total PAH concentrations measured in the AF site are

shown in Fig. 2. The Department of Atmospheric

Sciences of the University of S*ao Paulo provided

meteorological data used in this work.

3. Results

3.1. PAH and TSP concentrations in the sites

PAHs associated to airborne particles in S*ao Paulo

were determined at three sites in the winter of 2000.

Parallel experiments were carried out in two different

sites at each time period: first, simultaneous measure-

ments at the AF and COT sites and secondly, at the AF

and CID sites.

Long sampling time is generally required to detect

atmospheric PAHs; however, prolonged exposure of

aerosol particles change their chemical composition.

Volatilization and/or chemical and photochemical

transformations lead to underestimated PAHs concen-

trations. Low molecular weight PAHs, volatile distrib-

uted compounds in gas and particles, can undergo

sampling artifact. On the other hand, nitro-PAHs can be

generated during sampling due to nitration reactions

(De Martinis et al., 2002).

Since the sampling equipment used in this study was

not appropriate to collect the most volatile PAHs

compounds and the recuperation efficiency of naphtha-

lene, acenapthylene, acenaphethene, and fluorene was

very low (p50%), concentrations of these PAHs were

not taken into consideration in this study.

In spite of restrictive method, measurements of

phenanthrene to benzo[g,h,i]perylene were performed

(Ciccioli et al., 1996) because it provides an enough mass

amount to detect atmospheric PAHs, nitro-PAHs and

oxi-PAHs.

Fig. 3 shows the daily individual PAH concentrations

for the AF, CID, and COT sites; nevertheless, no

similarities can be identified in the distributions of

individual compounds between sampling sites. Intrasite

comparison shows similar general temporal trends in

PAH concentrations. Daily PAH concentrations pre-

sented a large variability during the sampling period,

probably attributable to meteorological variations in

this period. The lowest PAH concentrations were found

on rainy days. Generally, the results show quite low

PAH levels in the whole sampling period. On the other

hand, winter 1999 data from a study carried out at the

same sampling site revealed much higher PAH levels

(Fig. 4). Dry days with strong solar radiation and

several thermal inversion episodes occurred in the winter

of 1999 (Montero et al., 2001). Total daily PAH

concentrations reached a mean of 4.36 ngm�3, ranging

from 0.312 to 16.9 ngm�3 in 1999 (unpublished results),

whereas a mean of 2.73 ngm�3, with a range of 0.065–

31.2 ngm�3 was found in the present study.

In Fig. 5, PAH profiles for the sampling sites studied

are presented. Samples collected in the CID site had the

highest PAH levels (av. 3.10 ngm�3), followed by the

AF (av. 2.7 ngm�3) and COT (av. 1.92 ngm�3) samples.

A summary of individual and total PAH concentration

ARTICLE IN PRESS

10 12 14 16 18 20 22 24 26 28 30 1 3

8

16

24

10 12 14 16 18 20 22 24 26 28 30 1 340

60

80

100

10 12 14 16 18 20 22 24 26 28 30 1 30

10

20

30

10 12 14 16 18 20 22 24 26 28 30 1 30

6

12

18

August September

Temperature (ºC)

Precipitation (mm)

Radiation (MJ m-2)

Total PAH (ng m-3)

Relative humidity (%)

40

20

010 12 14 16 18 20 22 24 26 28 30 1 3

Fig. 2. Meteorological parameters in S*ao Paulo recorded at the

AF site (profiles of temperature, �C; relative humidity, %;

precipitation volume, mm; total solar irradiance, MJ/m2) and

total PAH concentration, ngm�3, at the AF site.

P.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–30183012

ranges, averages, and standard deviations are provided

in Table 2. The InP (16%), BPe (14%), and Chr, BbF

(13%) compounds were the most abundant PAH

compounds in the CID site. The Chr, InP (16%), and

BPe (13%) were the most predominant compounds in

the AF samples, while BbF (19%), Chr (15%), and BeP

(13%) in the COT samples.

The gravimetric analysis of total suspended particles

(TSP) revealed that 23% of the samples presented

concentrations above the recommended World Health

Organization standard, but only one sample of CID site

presented maximum daily concentration above the

Brazilian guideline value (240 mgm�3). Average TSP

levels in the three sites studied are presented in Table 2.

As it was observed with average total PAH, the lowest

TSP concentration was found in the COT site

(52mgm�3) and the highest value was observed in the

CID site (122mgm�3).

ARTICLE IN PRESS

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Aug0

9

Aug1

1

Aug1

3

Aug1

5

Aug1

7

Aug1

9

Aug2

1

Aug2

3

Aug2

5

Aug2

7

Aug2

9

Aug3

1

Sep0

2

Co

nce

ntr

atio

n (n

g m

-3)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

Aug0

9

Aug1

1

Aug1

3

Aug1

5

Aug1

7

Aug1

9

Aug2

1

Aug2

3

Aug2

5

Aug2

7

Aug2

9

Aug3

1

Sep0

2

Co

nce

ntr

atio

n (n

g m

-3)

AF site

COT site CID site

Phe

Ant

Fla

Pyr

BaA

Chr

BbF

BjF

BeP

BaP

InP

DBA

BPe

Fig. 3. Intrasite and intersite comparisons: daily individual PAH concentrations for the sampling sites studied, S*ao Paulo, 2000.

P.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–3018 3013

TSP and TSP-bound total PAH concentrations are

correlated in the COT and CID sites (r2 ¼ 0:51 and 0.68,respectively), indicating that their sources and sinks are

similar. However, no correlation was observed between

them in the AF site. This result is consistent with other

studies carried out in temperate environments where a

very low degree of correlation between bound PAH and

TSP concentrations was found (Panther et al., 1999).

By comparing published results on benzo[a]pyrene

(BaP), an indicator of carcinogenic risk (Menichini et al.,

1999), it is possible to observe that relatively low

ambient levels of BaP were found in this study (av.

0.28, 0.17, and 0.13 ngm�3, for the CID, AF and COT

sites, respectively, and 55% of all samples with

concentrations o0.10 ngm�3). The results are compar-

able to those found in Los Angeles, USA (0.21 ngm�3)

(Venkataraman et al., 1994), Hong Kong, China

(0.15 ngm�3), Melbourne, Australia (0.17 ngm�3)

(Panther et al., 1999), and Munich, Germany (0.11–

0.86 ngm�3) (Schnelle-Kreis et al., 2001).

In this work, PAH concentrations found in the urban

sites were generally higher than those observed in Alta

Floresta, Amazon Forest (av. 2.04 ngm�3) during

the dry season, when biomass burning often occurs

(Vasconcellos et al., 1998).

3.2. Influence of meteorology on PAH levels

Atypical meteorological conditions were recorded in

S*ao Paulo City in the winter of 2000. The sampling

period was characterized by different mean ambient

ARTICLE IN PRESS

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Phe Ant Fla Pyr BaA Chr BbF BjF BeP BaP InP BPe

Co

nce

ntr

atio

n (n

g·m

-3)

1999

2000

Fig. 4. Comparison of the PAH levels in 1999 and 2000, winter,

AF site, S*ao Paulo.

0

0.1

0.2

0.3

0.4

0.5

0.6

Phe Ant Fla

Pyr

BaA Chr

BbF BjF

BeP

BaP InP

DB

A

BP

e

Co

nce

ntr

atio

n (

ng

m-3

)

CID

AF

COT

Fig. 5. PAH profiles found in the sampling sites studied, S*ao

Paulo, 2000.

Table 2

Mean PAH (ngm�3) and TSP (mgm�3) concentrations at three sites within the metropolitan area of S*ao Paulo

PAH Site AF Site CID Site COT

Average7SDa (nb) Average7SDa (nb) Average7SDa (nb)

Phe 0.05470.21 (21) 0.02370.03 (14) 0.01070.01 (11)

Ant 0.03170.08 (20) 0.0247 0.07 (14) 0.00770.004 (11)

Fla 0.1570.51 (22) 0.07470.07 (14) 0.09470.08 (11)

Pyr 0.1870.52 (22) 0.07970.08 (14) 0.1170.06 (11)

BaA 0.2670.78 (22) 0.4070.42 (14) 0.1370.11 (11)

Chr 0.4371.19 (22) 0.4070.34 (14) 0.2970.20 (11)

BbF 0.3070.56 (22) 0.4070.50 (14) 0.3870.46 (11)

BjF 0.05870.14 (22) 0.1170.16 (14) 0.07170.09 (11)

BeP 0.2570.77 (19) 0.3370.31 (14) 0.2370.17 (11)

BaP 0.1770.52 (22) 0.2870.29 (14) 0.1370.09 (11)

InP 0.4470.97 (21) 0.4970.54 (14) 0.21570.178 (11)

DBA 0.7670.12 (21) 0.06270.12 (14) 0.1170.08 (11)

BPe 0.3370.84 (20) 0.4370.49 (14) 0.1570.11 (11)

Total PAH 2.73 3.10 1.92

TSP 88745 (22) 122775 (14) 52741 (11)

aSD=standard deviation.bn=sample number.

P.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–30183014

temperature and relative humidity, as compared to those

found in August, when days are normally cold and dry.

On 16 and 28 August, two heavy rainfalls occurred in

the AF site and 10 rainy days were recorded in the whole

sampling period. PAH removal from the atmosphere is

clearly observed on those rainy days.

At the AF site, no significant correlations were found

between the daily PAH concentrations and the ambient

temperature, relative humidity, wind speed, and pre-

cipitation volume.

Local meteorological data on 14 August showed a

continental plume passing in S*ao Paulo coming from N

and NE directions in the morning, and a maritime

plume arriving in S*ao Paulo at 4 a.m. local time. Since

PAHs are normally associated with small particles that

generally have long residence times in atmosphere and,

for that reason have the potential to be transported to

quite long distances, industrial sources are likely account

for the higher total PAH concentration (31.2 ngm�3)

found on 14 August. The maritime influence of winds

from highly polluted industrial regions located near the

ocean (see Section 2.2) and the continental influence of

winds from northwestern S*ao Paulo City, known for its

heavy industrial activity, could have been responsible for

the maximum total PAH concentration found on this

date. Measurements of formaldehyde, acetaldehyde,

formic acid, and acetic acid carried out in parallel to

PAH measurements also revealed higher ambient levels

of these pollutants on 14 August (Vasconcellos and

Carvalho, in preparation).

In order to investigate the effect of photochemical

degradation on the intensity of solar radiation, a

comparison has been made between the relative amounts

of BaP and BeP for the AF site. On strong sunshine

days, BaP levels are reduced, while BeP levels remain

constant (Panther et al., 1999). According to the results

of BaP/BeP ratios for the AF site, the photochemical

degradation as a predominant removal process could

not be attributed as an explanation for the PAH levels.

In fact, no correlation was observed between daily PAH

concentrations measured at the AF site and total solar

irradiance. However, a greater amount of BeP, the more

stable isomer, than BaP was found for the AF samples

taken on some dates on which total solar irradiance

presented relatively high levels. For example, on 14

August, when pollutants from industrial sources were

supposedly transported to the AF site by air mass

parcels, levels of BeP and BaP were, respectively,

3.43 ngm�3 and 2.36 ngm�3, and the total solar

irradiance was 14.8MJ/m2. For this sampled aerosol,

the occurrence of photochemical degradation during the

transport may be suggested

In this study, BaP/BeP ratios were used to show the

relative concentrations of species during the sampling

period. Approximately 85% of the CID and COT

samples presented ratios o1, while only 40% of the AF

samples had ratios o1. Despite the small number of

samples taken, especially in the COT site, photochemical

degradation may be suggested as a factor contributing to

the variation in PAH concentrations in both the CID

and COT sites.

3.3. Influence of vehicular source PAHs on the sites

Concentrations of vehicular exhaust emissions in

tunnels are significantly higher than those found in

ambient air, and PAH profiles for these emission sources

may be proposed using PAH measurements in tunnel

atmosphere. The use of pure ethanol and a mixture of

approximately 80% gasoline/20% ethanol in the Brazi-

lian vehicular fleet results in different PAH profiles from

those found in other urban regions around the world,

and there is no study on PAH emitted directly from

ethanol and gasohol motor vehicular exhausts. Propo-

sals of the PAH emission sources in airborne particles in

S*ao Paulo City are still quite limited.

Certain PAH concentrations ratios may be used as

tracers for vehicular motor exhausts with different fuels

(Li and Kamens, 1993). In Table 3, individual and total

PAH concentrations, as well as the average TSP

concentrations for each tunnel studied, the JQT and

the MMT, at different sampling times are presented.

In the JQT, only LD vehicles are allowed to pass, and

emissions from gasohol and ethanol motor exhausts are

the local sources. In contrast, both LD and HD vehicles

move inside the MMT, and diesel, gasohol, and ethanol

vehicle emissions are the local sources. Since the number

of ethanol-fueled vehicles has decreased drastically

compared to gasohol-fueled vehicles in the MASP

(Montero et al., 2001), we assume that LD vehicles

inside the tunnels are mostly fueled by gasohol.

The most predominant PAHs found in each tunnel at

different sampling times, shown in Table 4, were used to

indicate possible tracers. Vehicular traffic features in the

tunnels studied, such as type and number of vehicles, are

also shown in Table 4. According to our results, pyrene

(av. 21%) followed by chrysene (av. 15%) and

fluoranthene (av. 14%) are emitted mainly from gasohol

vehicular motor exhausts, whereas chrysene (av. 21%),

pyrene (18%) and benzo[a]anthracene (av. 17%) are

emitted mainly from gasohol and diesel vehicular motor

exhausts. Our results suggest that benzo[a]anthracene is

probably a tracer of heavy-duty diesel vehicular emis-

sions (Miguel et al., 1998).

On the basis of our tunnel measurements and data

from other ambient studies, possible PAH sources were

proposed for the sites studied. The large amounts of

chrysene in the ambient samples of the AF site are likely

to have come from local vehicular emissions. Addition-

ally, industrial-oil burning emissions originated in the

industrial park located in Cubat*ao could also have

contributed to the high chrysene level (Kulkarni and

ARTICLE IN PRESSP.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–3018 3015

Venkataraman, 2000). Although vehicular emissions

seem to be the most important combustion processes

at the AF site, the predominance of indeno[1,2,3-cd]

pyrene may be attributed to wood burning emissions (Li

and Kamens, 1993). Considering that wood burning

processes were not observed near the sampling site,

PAHs emitted from wood combustion may have been

long-range transported. As meteorological conditions

are an important variable that controls the atmospheric

abundance of pollutants, it is possible that these PAHs

collected in the urban area of S*ao Paulo City originated

from the surrounding rural areas, eventually from the

cane sugar burning regions. In the CID site, the most

abundant PAH compounds were the higher molecular

weight species (indeno[1,2,3-cd]pyrene and benzo[g,h,i]-

perylene). In this sense, Kulkarni and Venkataraman,

2000, pointed out that InP, DBA, and BPe are

originated from coal and kerosene combustion emis-

sions, in addition to vehicular emissions. The great

relative abundance of ambient benzo[b]fluoranthene and

chrysene at the COT site, located near a highway with a

dense heavy-duty diesel vehicle traffic, suggests that

vehicular emissions, mainly from diesel-fueled vehicles,

are the most important sources in this sampling site

(Marr et al., 1999).

In order to explain qualitatively the relative impor-

tance of vehicular emissions in the urban atmosphere of

S*ao Paulo City, the PAH ratios found in both tunnels

were studied. The InP/BPe and BaA/Chr ratios, shown

in Table 5, were compared to those found in the

sampling sites. Among PAH ratios reported in previous

studies (Caricchia et al., 1999), only the InP/BPe and

BaA/Chr tunnels ratios could be used to suggest

vehicular emissions because their values fell into of

ranges of those found in the sampling sites. The InP/BPe

and BaA/Chr ratios ranged respectively from 0.99 to 1.5

ARTICLE IN PRESS

Table 3

Results of the PAH (ngm�3) and TSP (mgm�3) concentrations at different sampling times in both tunnels studied

PAH MMT JQT

8–10 a.m. 10–12 a.m. Av.a 10–12 a.m. 12 a.m.–2 p.m. 2–4 p.m. Av.b

Phe 0.05 0.05 0.05 0.008 0.05 0.08 0.04

Ant 0.03 0.05 0.04 0.007 0.06 0.06 0.04

Fla 0.20 0.13 0.16 0.25 0.25 0.32 0.27

Pyr 0.27 0.21 0.24 0.47 0.38 0.43 0.43

BaA 0.20 0.26 0.23 0.18 0.10 0.13 0.14

Chr 0.37 0.20 0.29 0.40 0.25 0.22 0.29

BbF 0.05 0.08 0.07 0.09 0.07 0.06 0.07

BjF 0.04 0.08 0.06 0.06 0.08 0.05 0.06

BeP 0.03 oDLc 0.03 0.05 0.05 oDLc 0.05

BaP 0.05 0.07 0.06 0.40 0.08 0.07 0.19

InP 0.03 0.05 0.04 0.35 0.05 0.05 0.15

DBA 0.03 0.05 0.04 0.30 0.06 0.05 0.14

BPe 0.06 0.08 0.07 0.09 0.12 0.14 0.12

Total PAH 1.42 1.31 2.66 1.61 1.65

TSP 199 308 253 571 474 419 488

an ¼ 2:bn ¼ 3:cBelow detection limit.

Table 4

Predominant PAH species in locally measured PAH profiles for vehicular emissions: type and number of vehicles in each tunnel at

different sampling times

Tunnel/sampling time Traffic volume Predominant PAH species (%)

MMT/8–10 a.m. 6931 LD+928 HD Chr (26%), Pyr (19%), BaA (14%)

MMT/10–12 a.m. 6746 LD+1091 HD BaA (20%), Pyr (16%), Chr (15%)

JQT/10–12 a.m. 4781 LD Pyr (18%), BaP (15%), Chr (15%)

JQT/12 a.m.–2:00 p.m. 5630 LD Pyr (24%), Fla (16%), Chr (16%)

JQT/2–4:00 p.m. 6113 LD Pyr (26%), Fla (19%), Chr (13%)

LD=light-duty vehicles; HD=heavy-duty vehicles.

P.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–30183016

and 0.35 to 1.5 for CID samples, 0.81 to 3.2 and 0.27 to

0.61 for COT samples and 0.06 to 10 and 0.12 to 6.5 for

AF samples. All the CID and COT InP/BPe ratios and

approximately one-half AF InP/BPe ratios are in

agreement with those observed in the JQT (0.36–3.9).

On the other hand, the CID (71%), COT (50%), and AF

(43%) BaA/Chr ratios are in agreement with those

found in the MMT (0.54–1.3). Concerning other

characteristic ratios presented in Table 5, no similarity

was found between them and the ambient air sample

ratios.

Since characteristics ratios of vehicular emissions were

observed in the most of the CID samples, it may be

proposed that vehicular emissions were the most

important PAH sources in the CID site, whereas other

sources besides vehicles contributed to the PAH levels in

the AF and COT sites.

4. Conclusions

Measurements of PAHs in airborne particles have

shown no similarity in the distribution of individual

compounds between the three sampling sites located

within the MASP. The urban site, where vehicular

emissions were indicated as being the most important

PAH sources, atmospheric PAH concentrations were

higher, whereas in the atmosphere of the urban site with

dense vegetation and the forest site, lower PAH levels

were observed.

By using our tunnels measurements, characteristic

PAH profiles from vehicular emissions of the fuels used

in S*ao Paulo are proposed. Pyrene followed by chrysene

and fluoranthene are emitted mainly from gasohol

vehicular motor exhausts, while chrysene, pyrene and

benzo[a]anthracene are emitted mainly from gasohol

and diesel vehicular motor exhausts. The InP/BPe and

BaA/Chr ratios from each tunnel studied have indicated

the contribution of vehicular emissions in the atmo-

spheric PAH levels found in the MASP. Vehicular

emissions were the most important PAH sources in the

urban site, whereas other sources besides vehicles

contributed to the PAH levels in the other sites studied.

The large variation in ambient PAH levels is still a

matter that is not fully understood. However, it seems to

be clear that they are controlled by meteorological

variation. Different local PAH emission sources, as well

as long-range transport from other urban, rural or

industrial areas may also affect their levels. Certainly,

further investigation is still necessary for a better

understanding of the relationship between PAH

emissions from primary anthropogenic sources into

the atmosphere, such as diesel, gasohol and ethanol

engines.

Acknowledgements

This work has been supported in part by grants from

FAPESP, Funda@*ao de Amparo "a Pesquisa de S*ao

Paulo (project no. 96/0143-4). C. S. Pool thanks CNPq,

Conselho Nacional de Desenvolvimento Cient!ıfico e

Tecnol !ogico, for the graduate fellowship. The authors

wish to thank Odon R. Sanchez-Ccoyllo and the

Department of Atmospheric Sciences of the University

of S*ao Paulo for the meteorological data provided.

References

Azevedo, D.A., Santos, C.Y.M., Aquino Neto, F.R., 2002.

Identification and seasonal variation of organic matter in

aerosols from Campos dos Goytacazes area, Brazil. Atmo-

spheric Environment 36, 2383–2395.

Caricchia, A.M., Chiavarini, S., Pezza, M., 1999. Polycyclic

aromatic hydrocarbons in the urban atmospheric particu-

late matter in the city of Naples (Italy). Atmospheric

Environment 33, 3731–3738.

Cecinato, A., Ciccioli, P., Brancaleoni, E., Brachetti, A.,

Vasconcellos, P.C., 1997. PAH as candidate markers for

biomass burning in the Amazonia forest area. Annali di

Chimica 87, 555–569.

Ciccioli, P., Cecinato, A., Brancaleoni, E., Frattoni, M.,

Zacchei, P., Miguel, A.H., Vasconcellos, P.C., 1996.

Formation and transport of 2-nitrofluoranthene and 2-

nitropyrene of photochemical origin in the troposphere.

Journal of Geophysical Research 101 (D14), 19567–19581.

De Martinis, B., Okamoto, R.A.B., Kado, N.Y., Gundel, L.,

Carvalho, L.R.F., 2002. Polycyclic aromatic hydro-

carbons in a bioassay-fractioned extract of PM10 collected

in S*ao Paulo, Brazil. Atmospheric Environment 36,

307–314.

Fernandes, M.F., Brickus, L.R., Moreira, J.C., Cardoso, J.N.,

2002. Atmospheric BTX and polyaromatic hydrocarbons in

Rio de Janeiro, Brazil. Chemosphere 47, 417–425.

Halsall, C.J., Sweetman, A.J., Barrie, L.A., Jones, K.C., 2001.

Modelling the behaviour of PAHs during atmospheric

transport from the UK to the Artics. Atmospheric

Environment 35, 255–267.

Junker, M., Kasper, M., Roosli, M., Camenzind, M., Kunzli,

N., Monn, Ch., Theis, G., Braun-Fahrlander, Ch., 2000.

Airborne particle number profile, particle mass distribution

and particle-bound PAH concentrations within the city

environment of Basel: and assessment as part of

the BRISKA Project. Atmospheric Environment 34,

3171–3181.

ARTICLE IN PRESS

Table 5

PAH ratios found in both tunnels studied

MMT JQT

BaA/Chr 0.54–1.3 0.40–0.58

InP/BPe 0.51–0.57 0.36–3.9

P.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–3018 3017

Kulkarni, P., Venkataraman, C., 2000. Atmospheric polycyclic

aromatic hydrocarbons in Mumbai, India. Atmospheric

Environment 34, 2785–2790.

Li, C.K., Kamens, R.M., 1993. The use of polycyclic aromatic

hydrocarbons as source signatures in receptor modeling.

Atmospheric Environment 27A, 523–532.

Marr, L.C., Kirchstetter, T.W., Harley, R.A., Miguel, A.H.,

Hering, S.V., Hammond, S.K., 1999. Characterization of

polycyclic aromatic hydrocarbon in motor vehicles fuels

and exhaust emissions. Atmospheric Environment 33,

3091–3099.

Masclet, P., Cachier, H., Liousse, C., Wotham, H., 1995.

Emission of polycyclic aromatic hydrocarbons by savannas

fires. Journal of Atmospheric Chemistry 22, 41.

Menichini, E., Berolaccini, M.A., Taggi, F., Falleni, F.,

Monfredini, F., 1999. A 3-year study of relationships among

atmospheric concentrations of polycyclic aromatic hydro-

carbons, carbon monoxide and nitrogen oxides at an urban

site. The Science of the Total Environment 241, 27–37.

Miguel, A.H., Kirchstetter, T.W., Harley, R.A., 1998. On-road

emissions of particulate polycyclic aromatic hydrocarbons

and black carbon from gasoline and diesel vehicles.

Environmental Science and Technology 32, 450–455.

Montero, L., Vasconcellos, P.C., Souza, S.R., Pires, M.A.F.,

Sanchez-CCoyolo, O.R., Andrade, M.F., Carvalho, L.R.F.,

2001. Measurements of atmospheric carboxylic acids and

carbonyl compounds in S*ao Paulo City, Brazil. Environ-

mental Science and Technology 35, 3071–3081.

Oros, D.R., Simoneit, B.R.T., 2001. Identification and emission

factors of molecular tracers in organic aerosols from

biomass burning. Part 2. Deciduous trees. Applied Geo-

chemistry 16, 1545–1565.

Panther, B.C., Hooper, M.A., Tapper, N.J., 1999. A compar-

ison of air particulate matter and associated polycyclic

aromatic hydrocarbons in some tropical and temperate

urban environments. Atmospheric Environment 33,

4087–4099.

Santos, C.Y.M., Azevedo, D.A., Aquino Neto, F.R., 2002.

Selected organic compounds in Latin American and Asian

cities. Chemosphere 36, 3009–3019.

Schnelle-Kreis, J., Gebefugi, I., Welzl, G., Jaensch, T., Kettruo,

A., 2001. Occurrence of particle-associated polycyclic

aromatic compounds in ambient air of the city of Munich.

Atmospheric Environment 35, S71–S81.

Vasconcellos, P.C., Ciccioli, P., Artaxo, P., Brancaleoni, E.,

Cecinato, A., Frattoni, M., 1998. Determina@*ao dos

hidrocarbonetos saturados e polic!ıclicos arom!aticos na

atmosfera Amaz #onica. Qu!ımica Nova 21, 386–393.

Vasconcellos, P.C., Carvalho, L.R.F., Carbonyls compounds

and carboxylic acids in urban, sub-urban and forest areas of

S*ao Paulo City, Brazil (in preparation).

Venkataraman, C., Lyons, J.M., Friedlander, S., 1994. Size

distributions of aromatic hydrocarbons and elemental

carbon. 1. Sampling, measurement methods and source

characterization. Environmental Science and Technology

28, 555–562.

ARTICLE IN PRESSP.C. Vasconcellos et al. / Atmospheric Environment 37 (2003) 3009–30183018