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Atmospheric Environment 47 (2012) 541e545

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Atmospheric Environment

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Azaarenes in atmospheric particulate matter samples of three differenturban sites in east of France

Olivier Delhomme, Maurice Millet*

Laboratoire, Matériaux, Surface pour la Catalyse (UMR 7515 CNRS e Université de Strasbourg), Equipe de Physico-Chimie de l’Atmosphère, 1, rue Blessig,F-67084 Strasbourg Cedex, France

a r t i c l e i n f o

Article history:Received 14 January 2011Received in revised form13 June 2011Accepted 16 June 2011

Keywords:AzaarenesAmbient airSeasonal variationDiurnal variation

* Corresponding author.E-mail address: millet@unistra.fr (M. Millet).

1352-2310/$ e see front matter � 2011 Published bydoi:10.1016/j.atmosenv.2011.06.044

a b s t r a c t

Azaarenes concentrations in East of France urban atmospheres through the period between April 2006and February 2007 are described. Sampling sites were chosen to be representative of three differentregions and were situated in Strasbourg (“Alsace region”), in Besançon (“Franche-Comté region”) and inSpicheren (“Lorraine region”). In order to compare the seasonal variability, the sampling campaigns havebeen performed during the four seasons in Strasbourg, and during two opposed seasons (summer andwinter) in Besançon and in Spicheren. Moreover, the sampling campaigns have been performed during6 h time intervals per day (04:00e10:00; 10:00e16:00; 16:00e22:00 and 22:00e04:00) to assess thediurnal variations of azaarenes concentrations. Mean total azaarenes concentrations were 2.8 ng m�3 inStrasbourg, 1.6 ng m�3 in Besançon and 1.0 ng m�3 in Spicheren. Seasonal variations in the azaarenesconcentrations occur with the greatest abundance of all species in the colder months when combustionsources are greatest and when azaarene compounds are mainly associated with the particle phase. Adiurnal variation of compound concentrations in the three sites, in warm period, has been observed inaccordance with the intensity of the vehicle circulation, with highest concentrations during the morning(04:00e10:00) and the evening (16:00e22:00). In cold period, there is no difference of concentrationbetween these two time intervals of high vehicle circulation in Strasbourg site and in Besançon site.Moreover, in Spicheren site, the highest concentrations were observed during the evening. In this way, itseems that the contribution of domestic heating influenced the diurnal variations of some compounds onthe three sites.

� 2011 Published by Elsevier Ltd.

1. Introduction

Azaarenes compounds are heterocyclic aromatic hydrocarbons,containing in the structure one nitrogen atom in place of a carbonatom. They are formed as a result of pyrolysis or incompletecombustion of organic matter (Finlayson-Pitts and Pitts, 1986). Ingeneral, the sources of azaarenes are largely analogous to those ofpolycyclic aromatic hydrocarbons (PAHs), namely vehicle exhausts,coal burning, bitumen spreading and tobacco smoking. They havealso been detected in charcoal-grilled meat (Wilhelm et al., 2000).

Azaarenes are found along with the PAHs in respirable partic-ulate matter from ambient air and primary sources. Somemembersof azaarenes, particularly four- and five-ring compounds, areknown carcinogens and mutagens, and also are of particularinterest to the environmental analytical community (Southworth

Elsevier Ltd.

et al., 1978; Sovadinova et al., 2006). Human exposure to azaar-enes occurs primarily through inhalation of polluted air and byingestion of food and water contaminated with combustion prod-ucts (IARC, 1983). Moreover, many studies have indicated thatquinoline, 8-methylquinoline, acridine and benzoquinoline areactive as tumour initiators on mouse skin. Also the bigger azaar-enes, like the benzacridines, are carcinogenic and teratogenic (IARC,1983).

Azaarenes have becomewidespread in the environment throughthe extensive use of fossil fuels and have been detected in a widerange of different sources as fly ash obtained from incinerators (Nitoand Ishizaki, 1997), particulate matter from ambient air (Nielsenet al., 1986; Adams et al., 1982; Cautreels et al., 1977; Warzechaet al., 1999; Chen and Preston, 1998, 2004) automobile exhausts(Schmitter and Arpino, 1985; Handa et al., 1984; Yamauchi andHanda, 1987), petroleum (Snyder, 1969), cigarette smoke (Roggeand Hildemann, 1993), lake sediments (Wakeham, 1979), ground-water (Stuermer et al., 1982; Steinheimer and Ondrus, 1986) andsoils (Ko�ci et al., 2007; �Svabenský et al., 2007).

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Fig. 1. mean concentrations for each azaarene group at the three sites studied.

O. Delhomme, M. Millet / Atmospheric Environment 47 (2012) 541e545542

Azaarenes compounds are poorly documented in air and due totheir dispersion in the environment by the intensive used of fossilsfuels and of the potential toxicity of some of them, an investigationof their concentrations levels and spatial and temporal variabilitymust be performed in France and in particular in the east part ofFrance, region known to be strongly industrialised.

For this purpose, a GCeMS method for the determination of 19selected azaarenes in aerosol samples was applied to high-volumeair particulate matter collected between April 2006 and February2007 in East of France. In order to compare the seasonal variabilitythe sampling campaigns have been performed during the fourseasons in Strasbourg, and during two opposed seasons (summerand winter) in Besançon and in Spicheren. Moreover, the samplingcampaigns have been performed during 6 h time intervals per day(04:00e10:00; 10:00e16:00; 16:00e22:00 and 22:00e04:00) toassess the diurnal variations in azaarenes concentrations. Thetarget azaarenes, ranging from 2 to 5-ringed structures, include 8-methylquinoline (8 mq), 2-methylquinoline (2 mq), isoquinoline(IsoQ), 6-methylquinoline (6mq), 2,6-dimethylquinoline (2,6 dmq),2,4-dimethylquinoline (2,4 dmq), benzo[h]quinoline (B[h]q), acri-dine (Acr), phenanthridine (Phen), benzo[f]quinoline (B[f]q), benz[c]acridine (B[c]a), benz[a]acridine (B[a]a), 7,10-dimethylbenz[c]acridine (7,10-Dmeb[c]a), 7,9-dimethylbenz[c]acridine (7,9-Dmeb[c]a), 10-azabenzo[a]pyrene (10-Ab[a]py), dibenz[c,h]acridine (Db[c,h]a), dibenz[a,h]acridine (Db[a,h]a), dibenz[a,c]acridine (Db[a,c]a) and dibenz[a,j]acridine (Db[a,j]a).

2. Materials and methods

2.1. Reagents and chemicals

Dichloromethane, n-hexane and acetonitrile of HPLC gradequality were purchased from VWR International (Fontenay-sous-Bois, France). The azaarenes standards 8-methylquinoline, iso-quinoline, 6-methylquinoline, 2,6-dimethylquinoline, 2,4-dimethylquinoline,benzo[h]quinoline, phenanthridine, benzo[f]quinoline, 7,10-dimethylbenz[c]acridine, 7,9-dimethylbenz[c]acri-dine and dibenz[c,h]acridine were supplied from Aldrich (L’Isled’Abeau,France), while 2-methylquinoline, acridine, benz[c]acri-dine, benz[a]acridine, 10-azabenzo[a]pyrene, dibenz[a,h]acridine,dibenz[a,c]acridine and dibenz[a,j]acridine were purchased fromCluzeau Info Labo (Courbevoie, France). 1,3,5-triphenylbenzenewasalso purchased from Cluzeau Info Labo and was used as internalstandard. Stock solutions of each azaarene at 1 g L�1 and calibrationstandard solutions were prepared in acetonitrile.

2.2. Sampling sites and method

Three sampling sites in different East of France regions (“Alsace,Franche-Comté and Lorraine”) were chosen to characterizeparticle-bound azaarenes in urban conditions. The first site waslocated in Alsace region on the roof of a building at the University ofStrasbourg close to Strasbourg downtown (275�000 inhabitants).The building is about 25 m tall from ground level in a mixedinstitutional and residential area. The district is an urban areaheavily impacted by traffic in quite the direction, due to its location:three main roads (about 500 m in northwest, 2 km in southwestand 1.5 km in south direction) and an intersection freeways (2 kmin northwest) which carries on average over 50�000 vehicles perday (about 3�000 diesel trucks). Moreover, they are several indus-trial activities close to the site, in particular the Kehl area,a Germany town to about 4 km in East direction. The second site, inFranche-Comté region, was located on a platform (w3 m height) ofa parking structure and was in a mixed institutional and residentialarea close to downtown Besançon (120 000 inhabitants). The

district is also an urban area but is just surrounded with main roadof weaker traffic than the sampling point of Strasbourg. Noimportant industrial area is present around the site. The last site, inLorraine region, was located directly on the ground level, in thevillage of Spicheren (3500 inhabitants), about 5 km between theurban area of Forbach and the urban area of Saarbrucken inGermany. This sampling point, in a residential area, was repre-sentative of background urban conditions but present less directlyheavy emissions from traffic compared to Besançon. At the threesampling sites, there was also a meteorological station supplyingtemperature, wind speed and direction and rainfall data. Samplinghave been carried out over 14-day periods between April 2006 andFebruary 2007 during two contrasted seasons (summer andwinter) at three sites and during all seasons at the site of Stras-bourg. Particulate matter (PM10) samples were simultaneouscollected to the three sites in four time intervals per day(04:00e10:00, 10:00e16:00, 16:00e22:00 and 22:00e04:00, localtime) with fresh sampling media used for each collection. Sampleswere collected onto quartz fiber filters (QM-A, Whatman, FlorhamnPark, NJ), 150mmof diameter, by use of a high-volume air samplingsystem (Digitel DA80, Switzerland) at a flow rate of 30 m3 h�1. Priorto sampling, quartz fiber filters were cleaned by Soxhlet extractionfor 24 h with a mixture of n-hexane/dichloromethane (50:50, v/v)to remove organic impurities and stocked to an oven at 80 �C. Aftersampling, filters were individual wrapped in aluminium foil andplaced in individual opaque reclosable poly bags, and kept ina �20 �C freezer until analysis.

2.3. Sample extraction and analysis

The filters for each 3-day sampling period were compositedaccording to the same time interval and climatic conditions, toincrease the mass of particle by samples (540 m3 by sample). Thefilters occurred during a precipitation were not integrated to thecombination. The new samples composed of three filters wereSoxhlet extracted for 20 h in a mixture of n-hexane/dichloro-methane (50:50, v/v). The extracted samples were concentrated toabout 600 mL by rotary evaporation.

All measurements were performed using a Thermo Quest GC2000 coupled to a Thermo Finnigan Trace MS detector (ThermoFisher Scientific, Les Ulis, France). For the gas chromatographicseparation, an OPTIMA-210 MachereyeNagel column was used(30 m � 0.32 mm, film thickness: 0.25 mm). Chromatographicconditions and detection limits (varied between 1.50 mg L�1 forbenz[c]acridine and 2.56 mg L�1 for dibenz[a,c]acridine) were pre-sented in details elsewhere (Delhomme and Millet, 2008). Detec-tion limits for 540m3 of air sampled varied between 2.75 pg m�3 to4.75 pg m�3. The samples were analyzed by electron ionisation (EI)at 70 eV in selected ion monitoring mode (two or three charac-teristic ions were selected).

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Fig. 2. seasonal mean concentration for each azaarene group in Strasbourg.

O. Delhomme, M. Millet / Atmospheric Environment 47 (2012) 541e545 543

3. Results and discussion

3.1. Analytical methodology

Initially, it was planned to analyze azaarenes by HPLC withfluorescence detection using 1,3,5-triphenylbenzene as internalstandard. However, analyzing Azaarenes by HPLC was not retainedespecially due to resolution problem in separating the differentcongeners (Delhomme and Millet, 2008). Since, the choice of 1,3,5-triphenylbenzene was initially selected for internal standard as itsnon presence in air samples and non interference with chromato-gram, it was decided to conserve it in GC. In addition, its GCeMSanalysis was easy and sensitive.

3.2. Mean concentration

Azaarenes were analyzed between April 2006 and February2007 during two contrasted seasons (summer and winter) at threesites and during all seasons at the site of Strasbourg. The number ofsample was the following: 64 samples for Strasbourg site, 32samples for Spicheren site and 32 samples for Besançon site.Among the 19 targeted azaarenes, only isoquinoline and 8-methylquinoline were never detected in samples independentlyof the sites. To further the interpretation of the data, azaareneswere broadly classified into four groups, namely 2-ring [2-ring ¼ 2mq þ 6 mq þ 2,6 dmq þ 2,4 dmq], 3-ring [3-ring ¼ B[h]q þ Acr þ Phen þ B[f]q], 4-ring [4-ring ¼ B[c]a þ B[a]a þ Dmeb[c]aþ 7,9-Dmeb[c]a] and 5-ring [5-ring¼ 10-Ab[a]pyþ Db[c,h]aþ Db[a,h]a þ Db[a,c]a þ Db[a,j]a] compounds. Fig. 1 presents the meanconcentrations for each compound group at three sites studied. Themean total azaarenes concentrations were 2.8 ng m�3 in

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Fig. 3. seasonal mean concentration for each azaarene group

Strasbourg, 1.6 ng m�3 in Besançon and 1.0 ng m�3 in Spicheren.Higher concentrations in Strasbourg than the two other sites couldbe explain by a more directly emissions from traffic and fromindustrial activities close to Strasbourg sampling site area.

At the three sites, the 2-ring compouds were found as the mostabundant group of azaarenes, followed by the 3-ring compounds,4-ring compounds and 5-ring compounds. These observationswere in accordance with the study of Osborne et al. (1997) relativeto atmospheric sample collected on the campus of the University ofLiverpool. The authors found also strong two-ring azaarenesdominance, with concentrations ranged between 0.04 and>6 ng m�3 (0.32 and 3 ng m�3 in Strasbourg), between about0.11e>3 (0.23e1.8 ng m�3 in Strasbourg) and 0.007e0.37 ng m�3

(0.20e0.72 ng m�3 in Strasbourg) for 3-rings and 4-rings species,respectively.

3.3. Seasonal variability

Significantly seasonal variability of azaarenes concentrationswas found at the three sampling sites with a clear maximum inwinter and a minimum in summer (Fig. 2 and Fig. 3). This seasonalvariationwas similar for all the group of azaarenes, excepted for the5-rings in Strasbourg, which present no significantly differencebetween the spring and the summer. The average temperatures inStrasbourg were 15.1 �C in spring, 21.9 �C in summer, 6.6 �C in falland 1.0 �C in winter. In Besançon, the average temperatures were20.7 �C in summer and �0.4 �C in winter, and in Spicheren, theaverage temperatures were 18.6 �C in summer and 0.2 �C in winter.Pearson correlations coefficients of mean concentrations of eachazaarenes group with the average temperature were calculated.The coefficient varied between �0.75 and �0.88 in Strasbourg,between �0.71 and �0.87 in Besançon and between �0.74and �0.88 in Spicheren.

These relatively strong negative correlations show furtherevidence that the concentrations decrease during the warmseasons.

Several factorsmay contribute to the strong seasonal trends. Theseasonal variation canmainly due to the gas/particle partitioning ofazaarenes. Indeed, Chen and Preston (1997) published resultswhich showed that 80% of azaarenes compounds are associatedwith the particles in the winter and over 60% of azaarenescompounds exist as vapour phase during the summer. Moreover,the authors shown that 2-rings species are dominantly in thevapour phase, 4-rings species in the particulate phase but that3-rings species are intermediate in their properties and are there-fore most likely to undergo active changes in their gas/particle

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in Besançon (left figure) and in Spicheren (right figure).

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16:00-22:00 22:00-04:00

Fig. 4. diurnal variations of the total azaarene concentration during the summerperiod.

O. Delhomme, M. Millet / Atmospheric Environment 47 (2012) 541e545544

behaviour. In our study, by considering the ratios of the azaarenesconcentrations between the winter and the summer season(Cwinter/Csummer) for each group of compounds, we observed thatthe values of this ratio are higher for the 2-rings compounds. Forexample in Strasbourg, the values of ratio were 9.2, 7.3, 4.1 and 3.2respectively for the 2-rings, 3-rings, 4-rings and 5-ringscompounds. These results shown that the concentrations of 2-rings species, compounds dominantly in the gas phase, are themore influenced by the temperature, showing an important effectof the gas/particle partitioning on the seasonal variability.

The 2-ring azaarenes concentrations are certainly influenced bythe phenomena of sampling artefact. However, the samplings aremade over short periods of 6 h and consequently this artefact willbe limited. In our knowledge nobody publishes anything about thisphenomenon on azaarenes. A comparative degree can be madewith the HAP where different authors evidence this problem butwhich is limited by short sampling periods as it is the case in thepresent study. Moreover, the purpose of the study is to compare theconcentrations of azaarenes on three different sites where thesampling follows the same experimental protocol. Consequently, itcan be possible to do some direct comparison between these threesites even if a part of the 2-ring azaarenes volatilized during thesampling.

The seasonal variation can also due to an increase of emissionduring the cold period especially on the 4-rings and 5-rings species,compounds non affected by the gas/particle repartition, notablywith a contribution of an additional source like the domesticheating. Strong correlation was observed between two and threerings (r2 ¼ 0.67), between three and four rings (r2 ¼ 0.59) and fourand five rings (r2 ¼ 0.76) azaarenes, for the Strasbourg area. This

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Fig. 5. diurnal variations of the total azaarene concentration during the winter period.

suggests that there was a very similar source of the compoundsover the year. On the three sites, the increase of emission during thecold period was equally at the origin of the seasonal variabilityobserved for all different ring size group of azaarenes.

Another factor could explain the seasonal variation was thephotochemical reactions. Pearson correlations coefficients ofseasonal mean concentrations for each azaarenes group with theaverage global irradiance have been calculated. The relatively weakcorrelations, on the three sites, show further evidence that thephotochemical reactionwas not the principle origin of the seasonalvariability observed.

3.4. Diurnal variability

The diurnal variation was performed between summer periodand winter period at the three sites (Figs. 4 and 5). For this inves-tigation, the mean total azaarenes concentrations were used,without distinction of the number of rings, in contrary to theprevious part.

At the three sites, in summer period, the concentrations profilesobserved for the azaarenes compounds were similar and were inaccordance with the intensity of the vehicle circulation, withhighest concentrations during the morning (06:00e10:00) and theevening (16:00e22:00), time interval corresponding to an impor-tant flux of vehicles. In Spicheren, there is not a significant differ-ence in concentration between midday/afternoon, evening andnight time intervals. One hypothesis to explain this, is that the siteis less impacted by traffic and this traffic is not typical of a town incontrary to the two other sites.

In winter period, the azaarenes concentrations profiles inStrasbourg site and in Besançon site were similar, with highestconcentrations during the morning (04:00e10:00) and the evening(16:00e22:00). In contrary in the summer period, there is nodifference of concentration between these two time intervals.Although, there is an increase of emissions from vehicles (Bjorsethand Ramdahl, 1985) during low air temperature, which cannotexplain the highest concentrations during the 16:00e22:00 timeinterval. Indeed, the intensity of the vehicle circulation in the sitesdoes not evolve between summer and winter periods. There is thusa new emission source of azaarenes which can be the domesticheating, with an important emission during the day and theevening. In Spicheren site, a maximum of azaarene concentrationswere observed during the 16:00e22:00 time interval. Thistendency can also be explained by the addition of domestic heating.

4. Conclusion

PM10 samples were collected to east of France between April2006 and February 2007 to characterise particle-bound azaarenesin urban condition. Sampling siteswere chosen to be representativeof three different regions and were situated in Strasbourg (Alsaceregion), in Besançon (“Franche-Comté region”) and in Spicheren(“Lorraine region”). Among the 19 targeted azaarenes, only iso-quinoline and 8-methylquinoline were never detected in samplesindependently from the sites. Higher concentrations in Strasbourgthan the two other sites were observed. At the three sites, the2-ring compounds were found as the most abundant group ofazaarenes, followed by the 3-rings compounds, 4-rings compoundsand 5-ring compounds. For all azaarenes, significantly seasonalvariability was found in the three sampling sites, with highestconcentration in winter period when combustion sources aregreatest and where the azaarenes compounds are mainly associ-ated with the particles phase. The diurnal variations of compoundconcentrations at the three sites, in warm period, have beenobserved in accordancewith the intensity of the vehicle circulation,

O. Delhomme, M. Millet / Atmospheric Environment 47 (2012) 541e545 545

with highest concentrations during the morning and the evening.In cold period, there is no difference of concentration betweenthese two time intervals of high vehicle circulation in Strasbourgsite and in Besançon site. It seems that the contribution of domesticheating influence the diurnal variations of someone compounds,especially in the Spicheren site.

Acknowledgements

Authors wants to gratefully thank the Atmospheric PollutionSurvey Networks from “Alsace, Lorraine and Franche-Comté” fortheir help in sampling.

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