Atmospheric Research 101 (2011) 631639

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Atmospheric Research

j ourna l homepage: www.e lsev ie r.com/ locate /atmosStudy of nitro-polycyclic aromatic hydrocarbons in fine and coarseatmospheric particles

Elba Calesso Teixeira a,b,c,, Karine Oliveira Garcia a,c, Larissa Meincke a, Karen Alam Leal a

a Fundao Estadual de Proteo Ambiental Henrique Luis Roessler, RS. Rua Carlos Chagas 55/802, 90030-020 Porto Alegre, RS, Brazilb Universidade Feevale, Programa de Ps-Graduao em Qualidade Ambiental. RS-239, 2755, 93352-000 Novo Hamburgo, RS, Brazilc Programa de Ps-Graduao em Sensoriamento Remoto e Meteorologia, UFRGS. Av. Bento Gonalves, 9500, 91501-970 Porto Alegre, RS, Brazila r t i c l e i n f o Corresponding author at: Fundao Estadual deHenrique Luis Roessler, RS. Rua Carlos Chagas 55/8Alegre, RS, Brazil.

E-mail address: gerpro.pesquisa@fepam.rs.gov.br (

0169-8095/$ see front matter 2011 Elsevier B.V.doi:10.1016/j.atmosres.2011.04.010a b s t r a c tArticle history:Received 30 November 2010Received in revised form 15 April 2011Accepted 19 April 2011The purpose of the present study was to evaluate six nitro-polycyclic aromatic hydrocarbons(NPAHs) in fine (b2.5 m) and coarse (2.510 m) atmospheric particles in an urban andindustrial area located in the Metropolitan Area of Porto Alegre (MAPA), RS, Brazil. The methodused was of NPAHs isolation and derivatization, and subsequent gas chromatography byelectron capture detection (CG/ECD). Results revealed a higher concentration of NPAHs,especially 3-nitrofluoranthene and 1-nitropyrene, in fine particles in the sampling sites studiedwithin the MAPA. The diagnostic ratios calculated for PAHs and NPAHs identified the influenceof heavy traffic, mainly of diesel emissions. The correlation of NPAHs with other pollutants(NOx, NO2, NO and O3) evidence the influence of vehicular emissions in theMAPA. The seasonalvariation evidenced higher NPAHs concentrations in the fine particles during winter for mostcompounds studied.

2011 Elsevier B.V. All rights reserved.Keywords:NPAHsPAHsCG/ECDMobile sourcesTrafficDiesel1. Introduction

The atmosphere of urban centers contains various kinds oforganic pollutants. Among them, there are several polycyclicaromatic hydrocarbons (PAHs) and nitro-polycyclic aromatichydrocarbons (NPAHs), which are carcinogenic and/ormutagenic compounds (Tang et al., 2005).

The detection and characterization of PAHs and NPAHs inenvironmental samples is a priority, since both classes ofcompounds are ubiquitous. NPAHs are a group of organiccompounds formed of two or more condensed benzene ringslinked by a nitro group (NO2). These compounds are widelydistributed in the environment and are mainly foundassociated with atmospheric particles.

NPAHs present in the atmosphere originate from primarysources, such as emissions frommobile sources, mainly dieselProteo Ambiental02, 90030-020 Porto

E.C. Teixeira).

All rights reserved.vehicle exhaust (Nielsen, 1984; Bamford et al., 2003). Inaddition, NPAHs are also formed in the atmosphere viareaction of their parent PAHs initiated by hydroxyl (OH)radicals during the day and by nitrate (NO3) radicals (in thepresence of NOx) during the night (Sderstrm et al., 2005;Atkinson and Arey, 1994) and/or the heterogeneous gasparticle interaction of the parent PAHs adsorbed ontoparticles with nitrating agents (Feilberg et al., 2001).

After being formed, and once released into the atmo-sphere, NPAHs are very persistent in the environment andcan be carried over long distances from their original source(Nielsen, 1984; Ciccioli et al., 1996). To make matters worse,these compounds have 2.105 times the mutagenic and 10times the carcinogenic potential compared to PAHs (Durantet al., 1996).

The temporal resolution of NPAHs in ambient air is limitedby the detection limits of current analytical techniques.Collecting more samples or increasing the analytical sensi-tivity is required to increase the detectability of PAHs andNPAHs in ambient air (Crimmins and Baker, 2006). Because ofthe complexity of the matrices of environmental samples, the

http://dx.doi.org/10.1016/j.atmosres.2011.04.010mailto:gerpro.pesquisa@fepam.rs.gov.brhttp://dx.doi.org/10.1016/j.atmosres.2011.04.010http://www.sciencedirect.com/science/journal/01698095

632 E.C. Teixeira et al. / Atmospheric Research 101 (2011) 631639effectiveness of the methods depends critically on the"cleanness'' of the NPAH fraction achieved in the NPAHisolation step (Jinhui and Lee, 2001). In the environment,NPAHsareusually foundat lowconcentrations (pg.g1g.g1)when compared to their parent PAHs (Feilberg et al., 2001);therefore, analysis techniques for detecting NPAHs must havehigh selectivity and sensitivity (Feilberg et al., 2001).

PAHs and NPAHs profiles measured by using a receptorresulted from the integration of several sources such aschange in wind direction, oxidant concentration, and emis-sion sources during the sampling period (Crimmins andBaker, 2006). These authors and others (Yamasaki et al.,1982; Mader and Pankow, 2000) reported that changes intemperature during a sampling period may alter PAHs andNPAHs profiles in the observed gas and particle distributions.

Most studies about NPAHs associated with atmosphericparticles have been usually studies about NPAHs in fineatmospheric particles (e.g. Hayakawa et al., 1995; Kawanakaet al., 2004; Albinet et al., 2008; Di Filippo et al., 2010). Theseauthors reported that most NPAHs were found in fineparticles, revealing an important contribution of thesecompounds to mutagenicity.

In Brazil, few studies have been conducted about NPAHs inthe atmosphere, among which we include those of theauthors Vasconcellos et al. (2008), Barreto et al. (2007), andPereira Netto et al. (2000).

The purpose of the present study is to identify andquantify the NPAHs associatedwith fine (b2.5 m) and coarse(2.510 m) atmospheric particles in an industrial/urban area(MAPA) heavily influenced by vehicle traffic, by applying theanalytical method of gas chromatography by electron capturedetection. The analysis of the influence of the major emissionsources was done by diagnostic PAHs and NPAHs concentra-tion ratios and by the correlation of NPAHs concentrationswith other atmospheric pollutants such as O3, NO, NO2 andNOx.

2. Area of study

The area chosen for this study was the metropolitan areaof Porto Alegre (MAPA) located at 2930S 3030S/5025W 5155W in the east of the state of Rio Grande do Sul, Brazil.With a total area of 9800 km2, it includes 31 counties and isthe most urbanized area of Rio Grande do Sul.

The metropolitan area of Porto Alegre is characterized bydifferent industrial typologies, including several stationarysources such as the Alberto Pasqualini oil refinery, two steelmills (Siderrgica Riograndense and Aos Finos Piratiniwhich do not use coke) and two coal-fired power plants(Termochar and So Jernimo). Despite the different indus-trial sources around Porto Alegre contributing to the totalemissions, the major contributions come from an estimated620,000 vehicles on local roads, representing 20% of the total3.1 million vehicles of the state (Teixeira et al., 2008).

Due to the geographical locationof theMAPA, the seasons arewell defined and the rain is evenly distributed throughout theyear. The historical rainfall average is 13001400 mmyear1

(Livi, 1999). Winter in this region is strongly influenced by coldair masses migrating from polar regions, and in summer there isa greater influence of tropical, maritime and continental airmasses.According to Kppen's international climate classificationsystem, the area of study has a climate described as Cfasubtropical climate with an average temperature above 22 Cduring the warmest month of the year (Livi, 1999).

The prevailing wind directions are east (E), east southeast(ESE), and southeast (SE) (Livi, 1999). During the day, windreaches its lowest speed at dawn and early morning, andhighest speed in the late afternoon, between 5 and 7 p.m. Thispattern is related to energy availability at the surface(sensible heat) during the day, intensifying local andmesoscale atmospheric circulations. The prevailing windresults from interactions of mesoscale phenomena, especiallysea/land breezes (from the Atlantic Ocean and the PatosLagoon) and valley/mountain breezes (from the nearby SerraGeral mountains to the north of the MAPA).

3. Methodology

3.1. Sampling

The sampling sites were locatedwithin theMAPA: Canoas,Sapucaia do Sul, and FIERGS (Porto Alegre), shown in Fig. 1.Samples of atmospheric particles were collected during acontinuous period of 24 h every 15 days between 2006 and2008 using a stacked-filter-units sampler (SFU) (Hopke et al.,1997), which separates fine and coarse particles: PM2.5 andPM2.510. The operational flow of the sampler (SFU) was16.7 L.min1 (Hopke et al., 1997). The particles werecollected with quartz filters. The filters were equilibrated ina desiccator at room temperature for 24 h andweighed beforeand after sample collection. Each filter was wrapped inaluminum cover and stored at 20 C until chemicalanalyses.

3.2. Extraction, cleanup and analysis

PAHs and NPAHs adsorbed onto the particulate matter(b2.5 mand2.510 m)contained in thefilterswere extractedin Soxhlet with dichloromethane (CH2Cl2) for 18 h (USEPA,1999). After this, extracts were separated/preconcentrated bycleanup procedure using silica gel column and three fractions ofeluents of different polarities (ASTM, 2004, modified; Dallarosaet al., 2005a, 2005b, 2008).

The aliphatic compounds were eluted in the first fractionby using 20 mL n-hexane, which was then discarded. ThePAHs were eluted in the second fraction, by using succes-sively 20 mL of amixture of n-hexane: dichloromethane (1:1)and 20 mL of the same solvents at 3:1 ratio. The volume ofboth elutions was collected in a single flask for subsequentvolume reduction. The NPAHs were eluted in the thirdfraction by using 20 mL of dichloromethane, with the elutedvolume being collected in a flask for subsequent volumereduction.

After isolation by cleanup, the derivatization of the third-fraction extracts was performed, in which NPAHS werefluorinated through specific chemical reactions with hepta-fluorobutyric anhydride (HFBA), according to the methodproposed by Jinhui and Lee (2001). After that, NPAHs analysis1-nitronaphthalene (1NNa), 2-nitrofluorene (2NNl), 3-nitro-fluoranthene (3NFl), 1-nitropyrene (1-NPyr) and 6-nitrochry-sene (6-NCry)was performed by gas chromatography/electron

Fig. 1. Location of the sampling sites.

633E.C. Teixeira et al. / Atmospheric Research 101 (2011) 631639capture detection (GC/ECD Varian CP-3800) and silica gelcolumn (CP - Sil 19 CB, 30 m0.25 m0.25 mm). Thefollowing chromatographic parameters were used: injectortemperature280 C;detector temperature300 C; temperaturegradient starting at 60 C, increasing 6 C.min1 up to 300 C,and staying there for 5 min. The splitless injection mode wasdone with a nitrogen flow of 1.5 mL.min1 and injected asample volume of 3 L We used the Galaxie Workstation Varian software for data processing. Quantificationwasdonebyexternal standardization, by using NPAHs standards (Aldrich,9099% purity).

We chose the GC/ECD method due to the electronegativecharacter of the nitro groups conjugated with the aromaticrings, which allows the detection of low concentrations and ahigher level of selectivity than other types of detectors(Castells et al., 2003).

The analyses of the second fraction (PAHs) were by gaschromatography coupled with mass spectrometry (Shi-madzu, model GCMS-QP5050A), using the SIM (single ionmonitoring) mode. The analytical details will not be shown,as they are the subject of a study submitted for publication toanother journal.

Calculation of the detection limit (DL) followed specifica-tions as in method TO 13-A of USEPA (USEPA, 1999), i.e.,DL=3.3.SD/a, where SD=standard deviation of concentra-tion among replicates of the lowest point of the curve (5 gL1) and a=slope of the calibration curve. The values areshown in Table 1, which also provides QL values, calculatedaccording to the same method.

Table 1 also shows the data of the calibration curves,where the coefficients of determination indicate linearity. Theprecision for all components is represented by the values ofthe standard deviation. DLs obtained were satisfactory,indicating that this methodology is suitable to be applied tosamples of atmospheric particles, in which it is expected thatNPAHs will be found at very low concentrations.

The accuracy of 15.06% was determined by the errorobtained from the mean values of replicates of the standardsolution (5 g L1) taken as a reference.

3.3. Concentration ratios

The concentration ratios were calculated in order toidentify the influence of heavy traffic, especially of dieselemissions. This diagnosis is facilitated by comparing datafound in the literature (Lodovici et al., 2003; Kavouras et al.,2001; Tsapakis et al., 2002; Lee et al., 2002).We calculated thefollowing diagnostic ratios of PAHs and NPHAs concentra-tions: fluoranthene to (fluoranthene+pyrene) [Flt/(Flt+Pyr)]; pyrene to benzo(a)pyrene (Pyr/BaP); nitro-polycyclicaromatic hydrocarbons to polycyclic aromatic hydrocarbon(NPAHs/PAHs); 1-nitropyrene to pyrene (1-NPyr/Pyr).

Table 1Results of calibration curve and statistical parameters of dispersion and quantification.

NPAHs TR (min.) conc. range (g L1) R2 SD DL (g L1) QL (g L1)

1-nitronaphthalene 21.4 515 0.986 1.89 0.140 1.402-nitrofluorene 29.4 515 0.997 1.92 0.0720 0.7203-nitrofluoranthene 34.5 515 0.974 1.31 0.139 1.391-nitropyrene 35.2 515 0.965 0.450 0.0330 0.3306-nitrochrysene 38.0 515 0.957 2.47 0.215 2.15

TR = retention time; R2 = linearity of the curve.SD = standard deviation of the concentration between replicates.DL = 3.3SD/a where.SD = standard deviation of the concentration between replicates. a = slope of the curve.QL = quantification limit (10DL).

634 E.C. Teixeira et al. / Atmospheric Research 101 (2011) 6316393.4. Atmospheric pollutants

The pollutants NO, NO2, NOx, and O3 were measuredcontinuously during 2007 and 2008. The equipment used inthe sampling included a nitrogen oxide analyzer (AC31M using chemiluminescence's method) and an ozone analyzer(O341M absorption of UV light with wavelength of 254 nm,LCD/UV Photometry Ozone). All the equipments were madeby Environnement S.A.

4. Results and discussion

Fig. 2 a,b,c show the mean concentrations of NPAHs insamples of fine (b2.5 m) and coarse (2.510 m) particles atthe three stations studied (Canoas, FIERGS and Sapucaia do Sul)in the Metropolitan Area of Porto Alegre (MAPA). Approxi-mately 73% of the studied NPAHs were found at higherconcentrations in the fine particles. In these particles, thehighest concentrations were found for 1-nitronaphthalene(Sapucaia : 0.469 ng.m 3); 2-nitrofluorene (Sapucaia:0.550 ng.m3, Canoas: 0.540 ng.m3); 3-nitrofluoranthene(Sapucaia :0.397 ng.m3, FIERGS : 0.686 ng.m3); 1-nitropyr-ene (Sapucaia : 0.575 ng.m3, FIERGS : 0.425 ng.m3); 6-nitrochrysene (FIERGS : 0.445 ng.m3). Among the NPAHsidentified in the present study and frequently studied byseveral authors (Bamford et al., 2003; Dimashki et al., 2000;Zwirner-Baier and Neumann, 1999; and others), we found 3-nitrofluoranthene and 1-nitropyrene, whose occurrence isattributed to influences of mobile sources, since the samplingstations are located near the BR-116 highway, and to therelative increase of the vehicle fleet (diesel and gasoline) inrecent years (Teixeira et al., 2008). The increase in NPAHsconcentration in the fine fraction, especially 3-nitrofluor-anthene and 1-nitropyrene is in agreement with resultsreported by some authors among them Jinhui and Lee (2001),Kawanaka et al. (2004), Albinet et al. (2008), and Kawanaka etal. (2008).

The concentration of the NPAHs in the coarse particlesranged between 0.144 ng.m3 and 0.857 ng.m3.In general,NPAHs showed lower average concentrations compared tothe fine particles, except for 1-nitronaphthalene (FIERGS:0.405 ng.m3,Canoas : 0.490 ng.m3) and 2-nitrofluorene(FIERGS : 0.857).

The most volatile compound should show relatively lowerconcentrations in the atmospheric particles as the othercompounds studied. NPAHs can be formed during thesampling process (Goriaux et al., 2006; Albinet et al., 2007a,2007b), since PAHs deposited on the filter are converted toNPAHs by the passage of NO2.

Sometimes, the various studies about the identification ofNPAHs associated with atmospheric particles cannot becompared, since they are not the samewith regard to samplingmethodologies and analytic techniques, thus producing differ-ent results. Although the studies shown in Table 2 were carriedout at different periods and have used different experimentalprocedures, they provide a general view for particle-associatedNPAHs in different cities around the world. Table 2 shows theresults of particle-associatedNPAHs in theMAPA and in severalparts of the world, conducted by different authors. Thesestudies show differences in equipment for sampling atmo-spheric particles: PM, PM10 and low-pressure impactor, amongother factors. Even if there is no uniformity in various factors,this study shows a certain agreement, especially with regard totype of source. The results on NPAHs concentrations found bythe various authors (Table 2) were lower than the dataobtained in the present study, except for La Providencia,where 3-nitrofluoranthene and 1-nitropyrene concentrationswere higher. The area of La Providencia (Chile-Santiago) is anurban area surrounded by hills and mountains ranging from500 to 2500 mabove sea level, producing limited air circulationand weak dispersion mechanisms, especially during winter,below thermal inversion heights (Sienra et al., 2005). Meteo-rological conditions are one of the several factors that influenceNPAHs concentrations in atmospheric particles.

The concentrations of 1-NPyr in this study were higherthan the remaining results shown in Table 2. These resultsimply that diesel-powered vehicles are large contributors of1-NPyr in the MAPA, when compared to other parts of theworld. The occurrence of 1-NPyr in sampling sites in urbanareas is a marker for diesel engine in the atmosphere, asreported by some authors (Hien et al., 2007), as thiscompound has been proved to be emitted mainly by diesel-powered engines.

However, the results obtained by Di Filippo et al. (2010)for the fine fraction (b2.5 m) were lower than thoseobtained in the present study. This might be because the LaSapienza sampling site is not influenced by direct emissions.

The NPAHs most relevant for our study were those fromdirect emissionsproducedby incomplete combustion (Bamfordand Baker, 2003; Nielsen, 1984). Those NPAHs (e.g. 2NFl and2NPyr) formed by chemical reactions among PAHs were notstudied herein; however, it is important to explain which kind

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Table 2NPAHs (ng.m3) mean concentrations associated with atmospheric particles in the MAPA and other parts of the world.

Sampler type Source type 1-NNa 2-NNl 3-NFl 1-NPyr 6-NCry

Dimashki et al., 2000 PM Urban, near traffic site 0.089 NA 0.090 Feilberg et al., 2001 PM Traffic site NA 0.039 0.127 Marino et al., 2000 PM Urban NA NA 0.060Wilson et al., 1995 PM Urban 0.354 NA 0.0093Albinet et al., 2007a, 2007b PM10 Urban 0.208 0.0214 0.0137 0.0607 0.0331Las Condes a PM10 Urban 0.023 0.22 0.074Providencia a PM10 Urban, near high traffic site 0.42 1.5 0.6Hien et al., 2007 PM Urban 0.0081Hien et al., 2007 PM Urban 0.0091Hien et al., 2007 PM Urban, near traffic site 0.073Di Filippo et al., 2010 Low-pressure impactor (PM2.5) La Sapienza b University of Rome b 0.00004 0.00015 0.0002This study c PM2.510 Urban, near high traffic site 0.98 0.63 0.27 0.24 0.22This study c PM2.5 Urban, near high traffic site 0.56 0.57 0.49 0.42 0.77

a Sienra and Rosazza, 2006.b Site not affected by direct emissions.c Mean concentration in the MAPA.

636 E.C. Teixeira et al. / Atmospheric Research 101 (2011) 631639mentioned before, diesel traffic around the sampling sites isvery heavy. The three sampling stations (Canoas, Sapucaia doSul and FIERGS/Porto Alegre) studied are among the majorcontributors of atmospheric emissions (approx. 48.0%) in theMAPA, due to the great number of diesel vehicles, withapproximately 7767 tons of NOx emissions per year. In 2007and 2008, diesel consumption in these areas was 401,150 m3

and 417,829 m3, respectively. Diesel vehicles are an importantsource of NOx, and they produce five times the amount of NOxper volume of burnt fuel, when compared to gasoline vehicles(Gaffney and Marley, 2009).

NOx and O3 showed a significant negative correlation. Thenegative correlation of NOx with O3 confirms the so-called"titration" effect of NO on O3; NO reacts with O3 to produceNO2 (NO+O3NO2+O2).

Fig. 3 a,b show themean concentrations of NPAHs in winterand summer b2.5 m and 2.510 m fractions of 1-nitro-naphthalene, 2-nitrofluorene, 3-nitrofluoranthene, 3-nitropyr-ene and 6-nitrochrysene in the MAPA. Nitro-PAHconcentrations were higher in the fine particles for allcompounds studied, except for 2-nitrofluorene (winter), 3-nitrofluoranthene (summer) and 1-nitropyrene (summer).NPAHs mean concentrations during winter months rangedbetween 0.238 ng.m3 and 0.750 ng.m3 for thefine particles.Table 3Concentration ratios of PAHs and NPAHs in the atmosphere of the MAPA and other

Authors Sampler type Source type

Sapucaia a PM2.5 PM2.510 Urban, near high traffic sCanoas a PM2.5 PM2.510 Urban, near high traffic sFIERGS a PM2.5 PM2.510 Urban, near high traffic sTang et al. (2005) c High-volume air samplers UrbanFang et al. (2004) c PM2.5 PM2.510 UrbanKavouras et al., 2001 b PM2.5 UrbanGuo et al., 2003 c PM2.5 and PM10 UrbanRavindra et al., 2006 c PM2.5 Diff. anthr. act.Ravindra et al., 2008 d

a This study.b Ratio : Mean fine (PM2.5) mean coarse (PM2.510).c Source (diesel emissions).d (Diesel-engine vehicles).Mean concentrations of these compounds in the coarseparticles ranged between 0.642 ng.m3 and 0.164 ng.m3.

When comparing the concentrations of the compoundsstudied in the fine fractions during winter and summer, wesee that all were higher in winter, except for 6-nitrochrysene.This compound showed a concentration of 0.238 ng.m3 (inwinter) and 0.258 ng.m3 (summer) in the fine fraction.During the summer, NPAHs mean concentrations rangedfrom 0.214 ng.m3 to 0.555 ng.m3 for the fine particles andfrom 0.216 ng.m3 to 0.420 ng.m3or the coarse particles.Generally, in summer the NPAHs concentration was lowerthan in winter, which can be explained by the highertemperatures and the photochemical degradation of NPAHs(Tang et al., 2005, Hayakawa et al., 2002).

Climatic conditions during the winter and the associationof these compounds with fine particles contribute to theaccumulation of NPAHs, as already reported in several studies(Cecinato et al., 1998; Di Filippo et al., 2007; Sienra andRosazza, 2000; Tang et al., 2002). The reasons for seasonalvariations include lower mixing heights and/or less disper-sion (Fujitani, 1986), as well as reduced solar radiation in thewinter which may account for the higher NPAHs concentra-tions in winter. Furthermore, many NPAHs are susceptible tophotodegradation, which depends on solar radiationparts of the world.

(Pyr/BaP) [Fluo/(Fluo+Pyr)] [NPAHs]/[PAHs] 1-Npyr/pyr

ite 2.41.2 b 0.520.47 b 0.650.42 b 0.471.7 b

ite 1.91.0 b 0.560.53 b 0.490.50 b 1.11.1 b

ite 3.12.5 b 0.500.51 b 0.740.73 b 2.41.6 b

0.13 0.36 0.350.70

10

Table 4Correlations of NPAHs with atmospheric pollutants in the MAPA.

1NNa 2 NNl 3 NFl 1Npyr 6 Ncry NO NOx NO2 O3

1 NNa 1.0 0.23 0.52 0.50 0.21 0.24 0.17 0.11 0.242 NNl 1.0 0.41 0.02 0.63 0.34 0.19 0.08 0.283 NFl 1.0 0.68 0.46 0.36 0.48 0.45 0.211Npyr 1.0 0.25 0.49 0.51 0.43 0.316 Ncry 1.0 0.51 0.39 0.31 0.23NO 1.0 0.94 0.86 0.54NOx 1.0 0.98 0.65NO2 1.0 0.60O3 A 1.0

Correlations in bold type are significant at Pb0.05.

637E.C. Teixeira et al. / Atmospheric Research 101 (2011) 631639(Kamens et al., 1994; Fan et al., 1996b; Feilberg and Nielsen,2000; Hayakawa et al., 2002). During the period of study, themeteorological conditions were variable. The winter in 2006was drier, with less rainfall and lower wind speed due toincreased persistence of atmospheric blockade systems in thearea of study, while 2007 showed higher humidity, rainfalland wind speed due to the higher incidence of cold fronts andextra-tropical cyclones in the area of study. Due to thesemeteorological conditions, no alterations in NPAHs concen-trations could be observed in 2006 and 2007.5. Conclusions

The study of NPAHs associated with atmospheric particlesb2.5 m and 2.510 m in an industrial/urban area heavily0

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Fig. 3. a,b. NPAHs seasonal variation in atmospheric particles b2.5 m and2.510 m in the MAPA.influenced by vehicle traffic allowed the characterization ofthe main sources of these compounds in the MAPA. Vehicularemissions from the combustion of fuels, such as diesel oil,contributed significantly with NPAHs, as there is a greatnumber of vehicles in this area.

NPAHs, especially 3-nitrofluoranthene and 1-nitropyrene,prevailed in fine particles, and the fact that these sites arelocated near highways reveals that these compounds origi-nate from direct emissions, particularly diesel emissions.

The concentration ratios of PAHs and NPAHs in theatmosphere allow us to conclude that heavy traffic is theprevailing influence in the area of study (MAPA).

The correlations of NPAHs (3-nitrofluoranthene and 1-nitropyrene) with NOx (NO2, and NO) confirm the influenceof vehicular emissions in the MAPA.

Winter climatic conditions and the association withfine particles are contributing factors for a higher NPAHconcentration.

Although there are many studies about determiningNPAHs associated with atmospheric particles, there is stillno standardization as to the compounds analyzed, themethodologies employed for NPAHs sampling and detection.

As a suggestion and in conclusion, the sampling ofatmospheric particles should be improved so as to preventsorption of gaseous compounds on the filter and the chemicaldegradation of organic compounds.Acknowledgments

We are grateful to CNPq and Fapergs for their financialsupport.References

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Study of nitro-polycyclic aromatic hydrocarbons in fine and coarse atmospheric particles1. Introduction2. Area of study3. Methodology3.1. Sampling3.2. Extraction, cleanup and analysis3.3. Concentration ratios3.4. Atmospheric pollutants

4. Results and discussion5. ConclusionsAcknowledgmentsReferences