Atmospheric bulk deposition of PAHs onto France: trends from urban to remote sites

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  • Atmospheric Environment 36 (2002) 53955403

    Atmospheric bulk deposition of PAHs onto France: trendsfrom urban to remote sites

    B. Garbana,*, H. Blanchouda, A. Motelay-Masseib, M. Chevreuila, D. Ollivona

    aLaboratoire Hydrologie et Environnement, Ecole Pratique des Hautes Etudes, UMR Sisyphe 7619, Universit!e Pierre et Marie Curie,

    4 place Jussieu, case 122, 75252 Paris cedex 05, FrancebLaboratoire de G!eologie Appliqu!ee, UMR Sisyphe 7619, Universit!e Pierre et Marie Curie, 4 place Jussieu, 75252 Paris cedex 05, France

    Received 15 March 2002; received in revised form 11 June 2002; accepted 19 June 2002

    Abstract

    Fifty-eight weekly samples of atmospheric bulk deposition (dry and wet) were collected in France at six specic sites

    over a year. Urban, semi-rural, rural and forested sites were chosen on a transverse from West to East at the Paris

    latitude. Seasonal variations are described, with winter time concentrations 23 times higher than summer ones due to

    an increase in fossil fuel consumption in winter. When temperature did not exceed 121C, mean PAH concentrationsvaried from 221 ng l1 in Paris to 25 ng l1 at a rural site. About 50 km far from Paris, PAH concentrations decreased

    by two-thirds. Urban emissions have a local impact on the fallout contamination. Fluxes at the Paris site (from

    1571294 ngm2 d1) were from 2.56 times higher than in the rural and forested sites. In the latter sites, mean daily

    uxes (50 ngm2 d1) were close to those of high European mountains, considered as background levels. In rural sites,

    without treatment plant sludge spreading, atmospheric deposition is the major source of PAH inputs to soils.

    r 2002 Elsevier Science Ltd. All rights reserved.

    Keywords: PAHs; Bulk deposition; Transport; Flux; Seasonal variation

    1. Introduction

    Polycyclic aromatic hydrocarbons (PAHs) are ubiqui-

    tous contaminants of great environmental concern, by-

    products from the incomplete combustion of fossil fuels

    and wood. Forest res and volcanoes contribute to the

    PAH burden. However, residential heating, coke pro-

    duction, incineration and internal combustion engine

    are by far major sources of PAHs (Baek et al., 1991;

    Harvey, 1997).

    Sixteen unsubstituted PAHs, some of which are

    considered as being possible or probable human

    carcinogens, have been listed by the US Environmental

    Protection Agency (EPA) as priority pollutants. Once

    they enter the atmosphere, PAHs are redistributed

    between gas and particle phases and are subject to

    removal mechanisms such as oxidative and photolytic

    reactions and wet and dry deposition. During precipita-

    tion, PAHs both in gaseous and aerosol forms are

    scavenged from the atmosphere by rainwater (Ligocki

    et al., 1985a, b; Dickhut and Gustafson, 1995; Hillery

    et al., 1998). When deposited, they may be remobilised

    and transported by air masses and winds over long

    distances to settle again on land and water surfaces.

    Thus, PAHs have been found in samples collected in

    remote high European mountains (Steinberg et al., 1989;

    Carrera et al., 2001) and in Greenland polar ice (Jaffrezo

    et al., 1994; Masclet et al., 1995, 2000) or Canadian

    arctic (Barrie et al., 1992; Macdonald et al., 2000).

    Therefore, atmospheric transport and deposition are

    important pathways of PAHs to ecosystems far from

    source areas (Barrie et al., 1992) and shown by long-

    range transport modelling (Mackay and Wania, 1995;

    Di Toro and Hellweger, 1999; Pekar et al., 1999; Beyer

    et al., 2000; Halsall et al., 2001).*Corresponding author. Fax: +33-1-44-27-51-25.

    E-mail address: Brigitte.Garban@ccr.jussieu.fr (B. Garban).

    1352-2310/02/$ - see front matter r 2002 Elsevier Science Ltd. All rights reserved.

    PII: S 1 3 5 2 - 2 3 1 0 ( 0 2 ) 0 0 4 1 4 - 4

  • There is a growing concern about pollution by

    persistent organic pollutants (POPs) including PAHs.

    In May 2001, a global treaty for the regulation of POPs

    was signed: the Stockholm Convention which in-

    cludes instruments for the total elimination of 12 POPs

    on a global scale. Large-scale programs are conducted in

    relation to the long-range transboundary atmospheric

    pollution (EMEP) or their discharge into the sea

    (OSPAR). To these 12 POPs, the United Nations-

    European Community added the PAHs of which

    benzo(a)pyrene (BaP) is the most toxic. The objective

    is to control, reduce or eliminate discharges, emissions

    and losses of POPs.

    In this context, knowledge on the pollution level and

    its dispersion on regional and national scale is essential.

    In France, PAH deposition data have been collected in

    the Paris area (Ollivon et al., 1999, 2002), but no data

    are available for other sites.

    This study was part of the PIREN-Seine program

    concerning atmospheric loading of POPs on the river

    Seine catchment and their comparison with remote sites

    (Brittany and Vosges forest). Our purpose was to carry

    out measurements in bulk deposition (including wet and

    dry deposition) in urban, rural and forested regions in

    France and study the progression of the contamination

    by PAHs over a WestEast transverse, then to assess

    daily and annual PAH atmospheric loading.

    2. Experimental

    2.1. Study area

    According to the main wind directions (2202751)over France, sampling sites were set up on a transverse

    from West to East and close to meteorological stations,

    at Ouessant (481280N51030W), Pleumeur-Bodou(481460N31310W), Paris (481490N21290E), Coulom-miers (481500N31000E), Eclaron (481320N41450E),Abreschviller (481370N71O50E) (Fig. 1). Ouessant is asmall island (932 inhabitants) located at a few miles

    from the Western point of Brittany. The rain sampler

    managed by the Navy was located on the west coast in a

    wild moor. The Pleumeur-Bodou rain sampler was

    located in a rural area. The nearest city (18 000

    inhabitants) is 6 km away. The Paris rain sampler was

    located on the roof of a Paris university (Universit!e

    Pierre et Marie Curie), 25m above street level (Paris and

    suburbs population adds up to 11 millions inhabitants).

    The Coulommiers rain sampler was located in a

    suburban agricultural (rurban) village close to Cou-

    lommiers (14 000 inhabitants), 10 km away. The

    Eclaron rain sampler was situated in a rural region;

    the nearest city (33 500 inhabitants) is 40 km away to the

    Northeast. The collection site in Abreschviller (1300

    inhabitants) was in the Donon Massif (Vosges forest).

    All the sites were located in open areas, out of vegetation

    cover.

    Samples were collected weekly from 17 October 1999

    to 26 December 1999, and from 20 March 2000 to 10

    October 2000 for all sites, except at Eclaron where

    sampling began in March 2000. No snowfall occurred

    during the overall sampling periods. The bulk atmo-

    spheric deposition (wet and dry) were collected using

    open pyramidal stainless steel funnels with a 0.36m2

    collection area, collecting up to 70mm of rain without

    overow in a 25 l aluminium tank. The collectors receive

    both wet and dry deposition. All apparatus and

    containers were previously washed with Milli-Q water,

    then with HPLC quality grade acetone and hexane.

    Samples were mailed by express package within 2 days

    to the laboratory. Once in the laboratory, samples are

    stored at 41C in darkness and extracted within 48 h, thenthe extract was stored at 41C until analysis.

    2.2. Meteorological conditions

    Precipitation amounts, wind direction, and tempera-

    ture were obtained from Meteo France. At Paris, there

    were 175 rainy days during the study corresponding to a

    precipitation height of 825mm. At Abreschviller, annual

    precipitation height from 17 October 1999 to 08 October

    2000 was 1590mm (about twice higher than elsewhere:

    Ouessant 907mm; Pleumeur-Bodou 979mm; Coulom-

    miers 828mm). Considering only the sampling weeks,

    mean daily local temperatures ranged from 7.41C to12.81C at Ouessant, 7.113.41C at Pleumeur-Bodou,8.219.71C at Paris, 6.4171C at Coulommiers, 7.418.91C at Eclaron and 2.216.61C at Abreschviller. Theprevailing winds were westerly and southwesterly as

    shown in Fig. 1 where annual wind roses are displayed

    for three sites.

    2.3. Analytical procedure

    Raw samples including wet and dry deposition were

    extracted using a liquidliquid technique. Samples were

    shaken 3 times for 20min in a glass bottle, using 100ml

    of a hexane/methylene chloride mixture (v/v 85/15) for

    each litre of sample (Ollivon et al., 1999). Extracts were

    combined and reduced to 3ml on a rotary evaporator;

    after removal of sulphides by adding mercury, no

    further purication was performed. As the elution

    solvent for HPLC is acetonitrile/water, hexane had to

    be exchanged to acetonitrile. For doing so, methylene

    chloride and acetonitrile were added to the reduced

    extract in a 3/1/1 proportion for hexane/methylene

    chloride/acetonitrile, respectively. Then the mixture was

    concentrated to about 0.5ml and subjected to liquid

    chromatographic analysis.

    The identity of each PAH was conrmed by the use of

    a standard mixture (PAH-Mix 9 in acetonitrile from

    B. Garban et al. / Atmospheric Environment 36 (2002) 539554035396

  • Dr Ehrenstorfer GmbH, Augsburg, Germany) contain-

    ing the 16 PAHs recommended by the EPA method No.

    610: naphthalene (NAP), acenaphtylene (ACY), ace-

    naphtene (ACE), uorene (FLU), phenanthrene (PHE),

    anthracene (ANT), uoranthene (FTH), pyrene (PYR),

    benzo(a)anthracene (BaA), chrysene (CHR), benzo(b)-

    uoranthene (BbF), benzo(k)uoranthene (BkF), ben-

    zo(a)pyrene (BaP), dibenz(a,h)anthracene (DahA),

    benzo(g,h,i)perylene (BghiP), and indeno(1,2,3-cd)pyr-

    ene (IcdP). When extracted in the same conditions, the

    recovery efciency ranged from 91% to 113% (n 8).Chromatography of extracts was performed on a

    Dionex 4500i chromatograph, equipped with a Vydac

    201TP5415 column and two detectors, UV/visible and

    uorimetric. The instrumental conditions are described

    in detail elsewhere (Ollivon et al., 1995). Replicate

    analyses of standards gave relative standard deviations

    (RSD) from74% to78%, and detection limits, in ouranalytical conditions, ranged from 0.060.6 ng l1, both

    depending on the PAH analysed. Blanks of Albian

    aquifer groundwater stored and extracted in the same

    conditions were below detection limits and results were

    displayed without blank correction. Naphthalene, which

    is highly volatile, and acenaphtylene, which is weakly

    uorescent, were not quantied; therefore, total

    PAHs includes 14 compounds.

    3. Results and discussion

    3.1. Contamination level

    As our purpose was to follow the contamination trend

    on the whole transverse, in order to get enough water for

    POP analysis, extractions of PAHs were performed

    when a minimum of 10mm rainfall occurred at four sites

    at least. So during the 39 week sampling period, 58

    weekly bulk precipitations were analysed from October

    1999 to October 2000. Total PAH concentrations ranged

    from 7.6130 ng l1 at Ouessant, 1.565 ng l1 at Pleu-

    meur-Bodou, 51323 ng l1 at Paris, 16176 ng l1 at

    Coulommiers, 528 ng l1 at Eclaron and 4.881 ng l1

    at Abreschviller. Besides, in Paris, monthly sampling

    was performed all over the same year and total PAH

    concentrations in January reached 995 ng l1 (Ollivon

    et al., 2002).

    To display PAH concentration ranges (Fig. 2), two

    periods were distinguished according to air temperature.

    During the cold period (to121C), concentrations weregenerally higher, reecting the increase in fossil fuel

    consumption in winter. Seasonal variations of PAHs due

    to domestic heating have been widely described world-

    wide, for atmospheric samples (Baek et al., 1991; Smith

    and Harrison, 1996; Coleman et al., 1997; Cortes et al.,

    2000; Gigliotti et al., 2000) and precipitation over

    Europe (Hart et al., 1993; Halsall et al., 1997; Manoli

    et al., 2000; Kiss et al., 2001; Ollivon et al., 2002). The

    average PAH concentration in Paris was 221 ng l1. At

    Coulommiers, mean PAH concentration (85 ng l1)

    accounted for the impact of Paris pollution, but the

    latter was no longer detected at the eastern sites (25.3

    and 29.6 ng l1 on average at Eclaron and Abreschviller,

    respectively). At Ouessant and Pleumeur-Bodou sites,

    which we supposed to be background reference sites,

    mean PAH concentrations (54.6 and 40.2 ng l1, respec-

    tively) were generally higher than at the other rural and

    forest sites. At the Ouessant site, contamination by

    intensive boat trafc in the rail dOuessant might be

    considered as a potential source. Moreover, increases of

    PAH sorption with salinity in estuaries have been

    described (Brunk et al., 1997), and it is therefore

    possible that marine aerosols could act the same way

    by aggregating PAHs and trapping them.

    During the temperate period (t > 121C), the sametrend was observed with lower levels: from Paris to the

    eastern sites, mean PAH concentrations decreased from

    Fig. 1. Location of the sampling sites. Insets a,b,c, indicate the prevailing winds at the Pleumeur-Bodou, Paris and Abreschviller sites,

    respectively. Marne river catchment is gured in gray dotted line.

    B. Garban et al. / Atmospheric Environment 36 (2002) 53955403 5397

  • 124 to 19.8, 12.3, 14.9 ng l1, respectively, and levels at

    the western sites were 15.1 and 13.4 ng l1, respectively,

    at Ouessant and Pleumeur-Bodou.

    Winter concentrations were on average 23 times

    higher than the summer ones, and can be attributed to:

    (a) an increase in consumption of fossil fuel combustible;

    (b) an enhancement of the condensation of the PAH

    fraction in the gaseous phase as low temperatures lead to

    a decrease of the Henry constant. PAH concentrations

    were in the same ranges as those reported in the

    literature: (i) Kawamura and Kaplan (1983) at Los

    Angeles and vicinity described, at urban, semi-rural and

    rural sites PAH winter time concentrations of 250, 35,

    and 27 ng l1, respectively; (ii) Leuenberger et al. (1988)

    reported in urban rain water in Switzerland PAH

    concentrations of 130 ng l1 in summer, 210 ng l1 in

    spring, and 590 ng l1 in winter.

    Four compounds were generally predominant: phe-

    nanthrene, uoranthene, pyrene and chrysene, that

    represented 6271% of total PAH concentrations. The

    six potential carcinogenic PAHs as described by the

    International Agency for Research on Cancer (IARC)

    (i.e. BaA, BbF, BkF, BaP, DahA, and IcdP) represented

    on average 19% of the total PAHs, of which 3% was

    benzo(a)pyrene.

    3.2. Cross-country dispersion

    Nine transverses from West to East were established

    when meteorological conditions allowed simultaneous

    sampling at 4 sites at least. Concentration trends were as

    described previously: Paris is the most urbanised and

    industrialised site, and therefore the most polluted one.

    PAH concentrations in Paris were from 4 to 20 times

    higher than in the coastal, rural or forested sites.

    As sampling was performed weekly, it might include

    several rain events and, for such a long period, winds

    were rarely steady. Therefore, air mass trajectories were

    not investigated. However, during the rare weeks when

    winds came from West on the transverse, we observed

    that the percentage of the heaviest molecular weight

    (MW) compounds (C22) decreased from Paris to

    Abreschviller, whereas the lightest ones, acenaphtene

    and uorene, increased. Conversely, at the Pleumeu...

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