ilable at ScienceDirect

Atmospheric Environment 42 (2008) 6487–6495

Contents lists ava

Atmospheric Environment

journal homepage: www.elsevier .com/locate/atmosenv

Arsenic speciation study of PM2.5 in an urban area neara copper smelter

A.M. Sanchez de la Campa a,b,*, J.D. de la Rosa a, D. Sanchez-Rodas c,V. Oliveira c, A. Alastuey d, X. Querol d, J.L. Gomez Ariza c

a Associate Unit CSIC-University of Huelva ‘‘Atmospheric Pollution’’, University of Huelva, Campus Univ. El Carmen, E21071 Huelva, Spainb Department of Environment and Planning, University of Aveiro, Campus Univ. de Santiago, 3810 Aveiro, Portugalc Department of Chemistry and Science of Materials, University of Huelva, Campus Univ. El Carmen, 21071 Huelva, Spaind Institute of Earth Sciences ‘Jaume Almera’, CSIC, C/Lluis Sole i Sabaris s/n, 08028 Barcelona, Spain

a r t i c l e i n f o

Article history:Received 15 June 2007Received in revised form 25 March 2008Accepted 2 April 2008

Keywords:Atmospheric particlesPM2.5

Arsenic speciationCopper smelterSW Spain

* Corresponding author. Associate Unit CSIC-U‘‘Atmospheric Pollution’’, University of Huelva, CamE21071 Huelva, Spain. Tel.: þ34 959219821; fax: þ3

E-mail address: ana.sanchez@pi.uhu.es (A.M. San

1352-2310/$ – see front matter � 2008 Elsevier Ltddoi:10.1016/j.atmosenv.2008.04.016

a b s t r a c t

An arsenic speciation study has been performed in selected PM2.5 samples collected at anurban background monitoring station of the city of Huelva during 2001 and 2002, whichregisters the emission derived from a nearby copper smelter. The mean total As concentra-tion of the PM2.5 samples analyzed during 2001 (6.4 ng m�3) and 2002 (7.9 ng m�3) slightlyexceed the mean annual 6 ng m�3 target value proposed for PM10 by the European Com-mission for 2013.The speciation analysis shows that arsenate [As(V)] is the main arsenic species found,followed by arsenite [As(III)] (mean 5.8 and 1.2 ng m�3 for As(V) and As(III), in PM2.5,respectively, during 2001–2002).Three atmospheric and emission scenarios have been distinguished from a cluster analysisusing trace elements (Pb, Zn, Cu and Se) and As species derived from the copper smelter:(a) Anthropogenic, (b) Anthropogenic plus African dust outbreak and (c) Atlantic advec-tion. Highest Astotal mean concentration was found during the anthropogenic episodes(23.3 ng m�3), followed by the anthropogenic plus African dust outbreak episodes(9.2 ng m�3) and Atlantic advection days (2.2 ng m�3). These scenarios have been identi-fied in a previous work on the As species analysis in PM10.During Atlantic advection days, the As(III)/As(V) ratio in PM2.5 and PM10 was high, whereaslow As(III)/As(V) ratio in both PM2.5 and PM10 samples has been displayed during theanthropogenic scenarios. The As(III)/As(V) may be considered as a fingerprint of the originof the particulate matter.

� 2008 Elsevier Ltd. All rights reserved.

1. Introduction

Arsenic is a widely distributed metalloid in the earth’scrust and is present at a mean concentration of 4.8�0.5 mg g�1 (Rudnick and Gao, 2003). The sources of arsenicin the environment are both natural and anthropogenic

niversity of Huelvapus Univ. El Carmen,4 959219810.chez de la Campa).

. All rights reserved.

(Roy and Saha, 2002), occurring as a trace element in mostrock, soil, water and atmospheric dust (Mandal and Suzuki,2002).

In air from remote and rural areas, the annual meantotal arsenic (Astotal) concentrations range from 0.02 to4 ng m�3 (WHO, 2001). Mean total arsenic concentrationsin urban areas range from 3 to about 200 ng m�3 (op. cit),and also high concentrations have been measured in thevicinity of industrial sources (Querol et al., 2007).

Typical arsenic levels for the European region arecurrently quoted as being between 0.2 and 1.5 ng m�3 in

A.M. Sanchez de la Campa et al. / Atmospheric Environment 42 (2008) 6487–64956488

rural areas, 0.5 and 3 ng m�3 in urban areas and lower than50 ng m�3 in industrial areas (European Commission,2000; Putaud et al., 2004). The usual range of As concentra-tion levels for rural, urban and some industrial sites ofSpain reported by Querol et al. (2004b), are 0.3, 0.3–1.8and 5 ng m�3, respectively.

One of the main anthropogenic sources of arsenic inPM10 is a result of copper smeltering, which is consideredto be the origin of arsenic contamination episodes aroundthe world.

Examples of this type of activities have been referencedin Chile (Gidhagen et al., 2002; Hedberg et al., 2005), Ana-conda and Tacoma in USA and Sweden (see Hayes, 1997;Mandal and Suzuki, 2002).

In 2000, the World Health Organization Air QualityGuidelines cited a guideline recommended for As in theair. The lifetime risk was estimated to be 1.5�10�3/1 mg m�3 (WHO, 2001). The 2004/107/CE directive estab-lished a target value for As of 6 ng m�3 as an annualmean. Arsenic is considered to be one of the most toxicelements for human health. Continued exposure to a highconcentration of arsenic may produce an acute toxic effecton humans, which can be quickly diagnosed. However, lowdoses of arsenic do not result in an acute toxic effect, butmay give rise to cancer after prolonged exposure (Hayes,1997; Roy and Saha, 2002).

Several toxicological studies have demonstrated thatthe toxicity of arsenic is dependent on its chemical forms,oxidation state, physical state (gas or solution), rate ofabsorption into cells, rate of elimination and its chemicalnature in the toxic compound (Pershagen et al., 1982;Viraraghavan et al., 1992). Arsenic exists in several statesof oxidation: As(0) or as ion forms like As(V) arsenate,As(III) arsenite and As(III) arsine. It is generally recognizedthat the soluble inorganic arsenicals are more toxic thanthe organic ones, and the inorganic As(III) species aremore toxic than the inorganic As(V) (Francesconi and Kueh-nelt, 2003; Duker et al., 2005). Despite the distinct toxicityof the As species, the EU air quality Directive 2004/107/CEconsiders the total As content, and does not consider theindividual As species. Little research has been done in rela-tion to the As speciation in the atmospheric particulatematter (Slejkovec et al., 2000; Farinha et al., 2004; Oliveiraet al., 2005; Sanchez-Rodas et al., 2007).

Since 1998, several studies on air quality have beenperformed in the city of Huelva (Querol et al., 2002,2004a,b; Alastuey et al., 2006; Sanchez de la Campa et al.,2007). The city is located 4 km from an industrial site,where one of the main copper smelters of Europe is located.Under specific meteorological conditions, the emissions ofthe copper smelter may impact urban areas. Previous stud-ies on the As species in total suspended particles (Oliveiraet al., 2005) and PM10 (Sanchez-Rodas et al., 2007) in thearea of Huelva have shown that the presence of the moretoxic As(III) is directly related to an anthropogenic origin.

In this work, we present further results of the speciationof As in PM2.5 in Huelva during 2001–2002, and we com-pare them with the previous data of speciation of As inPM10 (Sanchez-Rodas et al., 2007). Also, we have correlatedthe results of speciation of As in PM2.5 and PM10 with othermeteorological and origin air masses data in order to

understand the control of these variables on the distribu-tion of As species. The aim of this study is to understandthe effects of the presence of arsenic species [As(III) andAs(V)] with distinct toxicity and the implications in thefuture EU Air Quality Directive.

2. Study area

The city of Huelva (approximately 140,000 inhabitants)is located in the southwest of the Iberian Peninsula, in theconfluence of the Odiel and Tinto rivers. Both rivers flowinto the Atlantic Ocean and form a common estuary (Riaof Huelva, Fig. 1). Huelva is near the Atlantic Ocean, wheretourist resorts and natural parks (e.g. Donana NationalPark) are located.

The main potential emission sources of heavy metals inthe study area derive from three major chemical and petro-chemical industrial states next to the city, which comprisePunta del Sebo, Nuevo Puerto and Tartessos. This industrialactivity generates a heavy impact on the water (Grandeet al., 2000; Davis et al., 2000) and air quality (Querolet al., 2002; 2004a,b; Sanchez de la Campa, 2004) of thestudy area, resulting in one of the most pollutedestuarine systems in Western Europe.

The main industrial emissions, next to the southern partof the city, are derived from a copper smelter and phos-phate factories (Punta del Sebo), which under specificmeteorological conditions may significantly impact urbanareas. The wind direction in this region is dominated bythree directional components (NE–ENE, NW–NNW andSSW–W), which are influenced by land–sea breeze circula-tion and the topography of the Tinto river (NE), the Odielriver (NW) and the coast line (SW) (Fig. 1). The marinebreeze dynamics show a complex pattern, which havebeen recently characterized by Adame (2005).

In winter, the Atlantic component (west) predominatesand is associated with low-pressure systems producingsignificant precipitation. In summer, sea breeze regimesprevail, increasing wind speed during the afternoons witha SW component (toward the continent) (Sanchez de laCampa, 2004). The air mass may be channelled throughoutthe valley of the Tinto river, transporting the pollutantsemitted in the area of Huelva toward the NE, which rendersthese areas vulnerable to possible impacts of emissionplumes from the industrial sites of Huelva (Sanchez de laCampa et al., 2007).

3. Methodology

3.1. PM and gases data

Fig. 1 shows the location of the monitoring stationselected for this study, Manuel Lois (37�1502700 N and6�5603200 W), which belongs to the Network of Quality ofthe Air of the Environmental Council of the Andalusia Gov-ernment. Manuel Lois is an urban background stationlocated in the southern part of the city. The station is situ-ated in an open area with no direct influence of road trafficor industry. This station registers levels of atmosphericparticulate matter in the range typical of other stations ofurban backgrounds (Querol et al., 2008).

Fig. 1. Map of the study area showing monitoring stations and industrial states. Wind rose diagram for the period 2001–2002 recorded at the Huelva station ofthe Meteorology National Institute of Spain.

A.M. Sanchez de la Campa et al. / Atmospheric Environment 42 (2008) 6487–6495 6489

Levels of PM10, PM2.5 and PM1 were monitored onreal time by means of a LASER-spectrometer dust monitorGRIMM 1107 (Labortechnik GmbH & Co. KG). PM10 andPM2.5 measurements were corrected by comparing themwith the levels obtained simultaneously by means of PM10

and PM2.5 high volume gravimetric method (Alastuey et al.,2006).

ManuelLoismonitoringstationisequippedwithautomaticinstrumentation to measure the PM10 levels (beta attenuation)and other gaseous polluting agents like SO2, NO2 and O3, whichcan be used to trace possible episodes of industrial pollution.

3.2. PM2.5 sampling

The dates of monitoring regimes of PM2.5 were one filterevery two weeks, sychronized with PM10 filters of Sanchez-Rodas et al. (2007). The sampling of PM2.5 was carried outusing circular filters of quartz micro fibre (diameter15 cm, QF20 Schleicher and Schuell) and a high volumesampler (MCV CAV-A/HF Model, 30 m3h�1) equipped

with a 2.5 mm sieve (PM2.5). The sampling was carried outfor 24 h periods. A total of 46 (24 in 2001 and 22 in 2002)filters were selected from a collection of 156 (91 of 2001and 61 of 2002). These samples were chosen due to theirhigh arsenic content in order to characterize the arsenicspecies and their possible origin. In this study, we haveselected the same numbers of filters of PM2.5 analyzed bySanchez-Rodas et al. (2007), in order to compare themwith the As species analytical results of PM10. As a result,the mean As content of the 46 samples selected is higherthan the mean concentration found for the whole collec-tion period, which is of 4 ng m�3 (Alastuey et al., 2006).

After sampling, PM2.5 filters were placed for 24 h ina desiccator box at room temperature. The levels of PM2.5

were obtained by standard gravimetric methods.

3.3. Chemical analysis

After the determination of PM2.5 levels, half of each filterwas digested in an acid media (2.5 ml HNO3: 5 ml HF:

A.M. Sanchez de la Campa et al. / Atmospheric Environment 42 (2008) 6487–64956490

2.5 ml HClO4) following the method proposed by Querolet al. (2001). All the acids were of Suprapur quality. Majorand trace elements were determined in the resulting diges-tion by means of Inductively Coupled Plasma–Optical Emis-sion Spectrometry (ICP–OES) and Inductively CoupledPlasma–Mass Spectrometry (ICP–MS). The mean precisionand the accuracy fall under typical analytical errors (inthe range of 3–10%), and were controlled by repeated anal-ysis of a 1/4 of filter loads with 5 mg of SRM 1633b (coal flyash) reference material (NIST, Gaithersburg, MD, USA). Thedetection limits obtained were of 0.1 ng m�3 for mostanalyzed trace elements. Blank filters were analyzed simul-taneously in the batches of their respective filter samplesand the corresponding blank concentrations weresubtracted for each sample. For the majority of the traceelements analyzed in the blank filters, the obtained valueswere less than 10 ng cm�2. High values have been foundonly for Cu (56 ng cm�2), Ba (44 ng cm�2) and Zn(25 ng cm�2).

Another fraction of each aerosol sample (1.2 cm2) wasextracted for the As speciation following the proceduredescribed in Oliveira et al. (2005). Briefly, this consists ofthe extraction of the arsenic species using a 100 mmol L�1

NH2OH$HCl solution as an extractant with the aid of micro-wave radiation (100 W) for 4 min.

The determination of individual arsenic species, As(III)and As(V) was performed by coupling High PerformanceLiquid Chromatography, Hydride Generation and AtomicFluorescence Spectrometry (HPLC–HG–AFS) (Gomez-Arizaet al., 2000). The detection limits obtained were of0.1 ng m�3 for As(III) and 0.4 ng m�3 for As(V).

In order to evaluate the efficiency of the extractionprocedure, the total As content of the samples was alsodetermined by mineralization in a muffle oven (Sanchez-Rodas et al., 2002). The total arsenic content was evaluatedby HG–AFS. SRM 1633b reference material was used for an-alytical evaluation of the digestion procedure, which is notsignificant differences between certified values (137.0�0.9 mg kg�1) and found value (136.2� 2.7 mg kg�1). Theefficiencies of the arsenic extraction of the PM2.5 samples,comparing the sum of arsenic species extraction to the totalarsenic content obtained in muffle oven, ranged between91 and 104%, with a mean of 97%.

3.4. Meteorological data, back-trajectories andstatistical study

The wind direction and speed data of Punta del Sebo mon-itoring station of the air quality network station of the Anda-lusia Government have been used in this work (Fig. 1).

Back-trajectories of five days have been calculated toclassify each day with PM2.5 sampling in accordance withthe origin of the air masses. We have distinguished anAtlantic advection (AA), North African (NAF), Mediterra-nean (ME), European (EU) and Regional (RE) origins ofthe air masses using the HYSPLIT4 model (Draxler andRolph, 2003, http://www.arl.noaa.gov/ready/open/hysplit4.html) with three different altitudes (500, 1500 and2500 m.a.s.l.). Also, the origins of North African air masswith a high concentration of suspended mineral dust havebeen identified by the evaluation of TOMS–NASA aerosol

index maps (Herman et al., 1997, http://toms.gsfc.nasa.gov/), SKIRON aerosol maps (Kallos et al., 1997, http://forecas-t.uoa.gr/), NAAPs aerosol maps (Naval Research Laboratory,http://www.nrlmry.navy.mil/aerosol/), and satellite imagesby NASA SeaWIFS (McClain et al., 1998, http://oceanco-lor.gsfc.nasa.gov/SeaWiFS/).

Also, a cluster analysis with the data corresponding tothe trace elements (Pb, Zn, Cu and Se) and As species anal-ysis has been performed using a STATISTICA� softwarepackage in order to verify the identified groups of filterusing meteorological scenarios.

4. Results and discussion

4.1. Suspended particulate matter andpollutant gas concentrations

The mean levels of PM10, PM2.5 and PM1 are summa-rized in Table 1. Mean PM2.5 level for 2001–2002 was19 mg m�3 and meets the requirements of the annual targetvalues considered in the recommended CE Directiveproposal of October 2005 (25 mg m�3). The mean PM2.5

levels measured at urban background and urban-industrialbackground monitoring sites in Spain range between 18–25 mg m�3 and 19–29 mg m�3, respectively (Querol et al.,2004a, 2008), and are similar to those obtained at ManuelLois monitoring station (19 mg m�3). The levels of PM2.5 ofother monitoring station in Europe also are in the rangeof Manuel Lois (Gotschi et al., 2005; Viana et al., 2007).Mean annual PM10 levels during 2001–2002 periods were37 mg m�3, not exceeding the EU limit value for 2005 of40 mg PM10 m�3 (EU, 1999).

Table 1 also shows the monthly mean during 2001 and2002 of the daily mean levels of NO2, SO2, and PM2.5/PM10

ratio measured at the station Manuel Lois. The NO2 displaysa seasonal evolution (maximum in winter and minimum insummer) and SO2 shows a zigzag pattern. The increasinglevels of NO2 and sporadic peaks of SO2 episodes duringJanuary–February and October–December are due to thefrequent episodes of local anthropogenic pollution (urbanand industrial) that took place during this period and arecorrelated with frequent atmospheric stagnating periods(Sanchez de la Campa et al., 2007).

PM2.5 accounting for 50–60% of PM10, and the PM2.5/PM10 ratio is maximum in winter and minimum in summer.During winter, the anthropogenic emissions derived fromthe industrial sites have a greater impact in the city ofHuelva (high PM2.5 levels). However in summer, maximumlevels of PM10 are interpreted by the local resuspension andan increase of the frequency of North African outbreakepisodes (Table 1).

Peaks of PM2.5 are correlated with increasing amountsof contaminant gases (NO2 and SO2), essentially derivedfrom the industrial sites and during sea-breeze episodes.

4.2. Trace element and As species levels

The mean, maximum and minimum levels of As(III),As(V), Astotal and trace elements in PM2.5 analysis aresummarized in Table 2. The selected trace elements areconsidered as tracers of the industrial activity. Table 2

Table 1Monthly mean levels of PM10, PM2.5 and PM1 obtained with the LASER-spectrometer, pollutant gases (NO2, SO2 and O3), and the frequency of the origin of airmass according to back-trajectories, in Manuel Lois monitoring station during 2001–2002

2001 PM10 PM2.5 PM1 NO2 SO2 O3 AA NAF ME EU REG

mg m�3 mg m�3 Frequency (%)

January 26 17 13 23 11 49 97 0 0 0 3February 46 27 21 27 12 50 68 21 7 4 0March 27 16 10 16 7 60 87 13 0 0 0April 36 13 9 13 4 75 97 0 0 0 3May 37 20 16 17 8 79 77 0 13 0 10June 47 18 13 15 6 67 47 37 3 0 13July 48 17 13 11 5 58 65 29 0 0 6August 45 20 16 14 6 58 61 26 0 0 13September 45 29 25 15 5 58 24 66 0 0 10October 30 16 11 20 8 36 60 37 0 0 3November 33 20 16 23 5 33 55 34 0 7 3December 36 22 20 26 8 27 56 28 12 4 0Annual 38 19 15 18 7 54 66 24 3 1 6

2002 PM10 PM2.5 PM1 NO2 SO2 O3 AA NAF ME EU REG

mg m�3 mg m�3 Frequency (%)

January 43 26 22 25 7 30 61 32 6 0 0February 41 24 21 22 5 39 64 36 0 0 0March 35 20 16 19 7 55 48 35 3 13 0April 33 18 15 15 6 67 83 3 0 10 3May 29 10 7 12 5 66 81 19 0 0 0June 43 19 14 13 6 55 30 70 0 0 0July 44 18 14 13 6 66 68 26 0 0 6August 44 22 19 12 5 58 77 19 0 0 3September 35 21 17 14 8 42 93 0 0 0 7October 30 21 17 17 7 42 74 23 0 0 3November 25 12 9 18 6 37 100 0 0 0 0December 33 22 16 21 6 33 87 7 0 7 0Annual 36 19 16 17 6 50 72 23 1 2 2

A.M. Sanchez de la Campa et al. / Atmospheric Environment 42 (2008) 6487–6495 6491

also contains the mean of the As species and trace elementsin PM10 are presented in Sanchez-Rodas et al. (2007), in or-der to compare it with PM2.5 analysis, and to know the con-trol of the size of the particulate matter on the Astotal and Asspecies, as well as in the ratio of As(III)/As(V).

The concentrations of As and of some of the selectedheavy metals in PM10 and PM2.5 of industrial origin areabove the usual range of levels found at urban background

Table 2Arsenic speciation and chemical characterization of the PM2.5 samples collected aRodas et al. (2007)

2001

PM2.5 (n¼ 24) PM10 (n¼ 25)

Mean Max. Min. Mean

PM 21 32 12 40As(III) 0.9 1.6 0.01 1.2As(V) 5.0 25.3 0.01 6.5Astotal 6.4 30.2 0.8 7.7

Cu 36.6 91.7 14.4 81.9Zn 50.8 166.0 0.01 64.5Cd 0.8 5.5 0.01 0.9Sb 0.9 2.0 0.03 2.4Pb 29.9 156.8 0.7 47.4Se 1.3 5.8 0.01 1.9Sn 2.3 9.9 0.43 2.6Ba 3.3 21.5 0.01 18.0Bi 1.6 9.6 0.001 2.0V 5.2 16.0 0.6 7.6

Results corresponding to PM as expressed as mg m�3 and the rest of variables as

monitoring stations in other Spanish cities (Querol et al.,2004b, 2008). The Astotal concentration in PM2.5 is higherin 2002 (7.9 ng m�3) than 2001 (6.4 ng m�3). High levelsof Cu, Zn and Se were determined (41.9, 39.5 and 1.2 and150.7, 151.9 and 5.9 ng m�3 as mean and maximum levels,respectively).

The mean levels of As(III) and As(V) in PM2.5 were 0.9and 5.0 ng m�3 in 2001, and 1.4 and 6.6 ng m�3 in 2002,

t the city of Huelva during 2001 and 2002, and mean of PM10 by Sanchez-

2002

PM2.5 (n¼ 22) PM10 (n¼ 25)

Mean Max. Min. Mean

21 33 7 371.4 2.7 0.1 2.16.6 56.2 0.01 7.87.9 56.6 1.0 9.5

47.2 209.6 11.2 124.728.1 137.7 9.3 43.6

0.7 5.3 0.01 0.81.1 2.8 0.43 2.1

26.1 164.2 2.2 34.31.0 6.0 0.01 1.91.4 5.0 0.01 2.05.6 68.6 0.9 26.01.4 6.0 0.01 1.43.6 15.7 0.9 6.6

ng m�3.

A.M. Sanchez de la Campa et al. / Atmospheric Environment 42 (2008) 6487–64956492

respectively. Previously published works on As species inparticulate mater are scarce, with most available datafrom samples collected in a traffic monitoring station(Slejkovec et al., 2000) and in a rural background monitor-ing station near a power station (Farinha et al., 2004). Thelevels of As species obtained in Huelva are higher thanthe concentration referenced (op. cit), and they are inter-preted due to the impact of the emissions of the coppersmelter located near the city of Huelva (Querol et al.,2002; Sanchez de la Campa et al., 2007). Alastuey et al.(2006) have documented that during the impact on theground of copper smelter emissions, the sampling ofPM10 and PM2.5 is characterized by high concentrations ofAs and other heavy metals (e.g. Cu, Zn, Pb, Se, Bi and Ni),and that the 85% of As in PM10 is concentrated in the finefraction (PM2.5).

The Astotal PM2.5/PM10 ratio was 0.83, during 2001–2002. This shows how As is concentrated in the fine sizeparticle. The accumulation of heavy metals in the finefraction of particulate matter has been reported by otherauthors (e.g. Fernandez Espinosa et al., 2001; Alastueyet al., 2006). The same pattern has been identified for theAs species: As(III)PM2.5/As(III)PM10 was 0.71; andAs(V)PM2.5/As(V)PM10 ratio was of 0.81. The concentrationof Astotal and As species in the fine size of the PM is a conse-quence of the combustion processes in the copper smelter.

Astotal was characterized by random peak concentra-tions associated with specific pollution episodes. Thiszigzag pattern also has been distinguished in other local

pollutants in PM2.5, such as Pb, Cu, and PO43� (Fig. 2), also

with a clear industrial related origin (Alastuey et al., 2006).In order to identify possible seasonal variations of trace

elements and As species in PM2.5 in the monitoring stationof Manuel Lois, the concentrations of As species have beenplotted vs. sampling period (2001–2002) (Fig. 3). As(III) andAs(V) display a zigzag pattern, which may be due to themode of operation in the copper smelter and the meteoro-logical scenarios. The chemical characterization and sourceapportionment analysis of PM, and intensive measure-ments in field campaigns to characterize the emissionplumes of several point sources was developing during2001–2002 (Alastuey et al., 2006). A mixed metallurgical-phosphate source was inferred by source apportionmentanalysis from the Bi, Cu, Cd, Pb, PO4

3�, As, and Zn chemicalassociation, with a contribution of around 11–12% forPM10 and PM2.5, and corroborated with the study of grain

Fig. 2. Daily mean concentration of sum As species,

size distribution and chemical characterization of PMfrom the major emission plumes (op. cit).

4.3. As episodes during atmospheric and emission scenarios

A cluster analysis using STATISTICA� software packagehas been performed on the basis of trace elements (Pb,Zn, Cu and Se) and As species analysis of 46 samples ofPM2.5. This study has been supported by the analysis ofmeteorological scenarios and back-trajectories. Threegroups of atmospheric and emission scenarios have beendistinguished: (a) Anthropogenic emissions (8 samples),(b) Anthropogenic emissions plus North African dust out-breaks (8 samples) and (c) Atlantic advection (30 samples).

Table 3 summarizes the mean, minimum and maximumconcentrations of PM, As(III), As(V) and Astotal in PM2.5 ofthe three scenarios described before. Moreover, Table 3also included mean PM and As species in PM10 previouslyreported by Sanchez-Rodas et al. (2007) in order to com-pare the concentrations obtained in PM2.5. The Astotal

mean concentration was high during the anthropogenicepisodes (23.3 ng m�3 in PM2.5 and 28.1 ng m�3 in PM10)following the anthropogenic plus African dust outbreakepisodes (9.2 ng m�3 in PM2.5 and 10.6 ng m�3 in PM10),and the Atlantic advection days (2.2 ng m�3 in PM2.5 and2.9 ng m�3 in PM10).

The Astotal PM2.5/PM10 ratio ranges between 0.87 and0.76 for the identified scenarios calculated with the dataof Table 3. This shows that the As is concentrated in thefine size particle. The same pattern has been identifiedfor the As species of the scenarios: As(III)PM2.5/As(III)PM10

range between 0.79 and 0.61; and As(V)PM2.5/As(V)PM10

ratio was of 0.91–0.73.A variation diagram of As(III)/As(V) in PM2.5 vs. As(III)/

As(V) in PM10 has been represented in Fig. 4, in order toknow the variation of the As species ratios in fine andcoarse particles under several scenarios.

All the analyses are displayed in a line 1:1 (correlationcoefficient R2¼ 0.79). This implies that the ratio of thespecies As(III)/As(V) is the same for both PM2.5 and PM10,and may prove the existence of chemical equilibrium ofthe As species.

During Atlantic advection days (Table 3), the Astotal

mean concentration was low (2.2 ng m�3 in PM2.5 and2.9 ng m�3 in PM10), and the As(III)/As(V) ratios in PM2.5

and PM10 were high (1 and 1.2, respectively) (Fig. 4).

and heavy metal (Pb and Cu), and phosphate.

Fig. 3. Daily arsenic speciation concentration (ng m�3) in PM10 and PM2.5 forthe study period. Black arrows: Atlantic advection episodes. Solid blackarrows: African outbreak episode. Solid grey arrows: anthropogenic plusAfrican dust outbreaks cause.

A.M. Sanchez de la Campa et al. / Atmospheric Environment 42 (2008) 6487–6495 6493

However, in the anthropogenic scenarios the Astotal meanconcentrations were highest (23.3 ng m�3 in PM2.5 and28.1 ng m�3 in PM10) with low As(III)/As(V) ratios in bothPM2.5 (0.05) and PM10 (0.06) samples (Fig. 4). In theseepisodes, the winds with S and SW components may trans-port the contaminants from the main emission source tothe monitoring station in the city of Huelva. In the anthro-pogenic plus African outbreak episodes, the concentrationof As was intermediate (9.2 ng m�3 in PM2.5 and10.6 ng m�3 in PM10) between the two former episodes.The frequent African dust outbreaks over Huelva may resultin an increase of mass levels of PM, but do not representa significant input of arsenic in comparison to the anthro-pogenic source. The As(III)/As(V) ratio from 0.16 in PM2.5

to 0.19 in PM10 samples are also intermediate comparedwith the other episodes (Fig. 4).

During the Atlantic advection scenario there arefrequent rainfall episodes. In this case, the As(V) concentra-tions decrease markedly with respect to As(III) in both

Table 3Mean, minimum and maximum arsenic species and PM2.5 concentrations for each

Anthropogenic African ou

(n¼ 8) PM2.5 (n¼ 9) PM10 (n¼ 8) PM

Mean Min. Max. Mean Mean

Concentration (mg m�3) 21 3 32 47 25As(III) (mg m�3) 1.1 0.0 2.7 1.4 1.3As(V) (mg m�3) 21.5 6.7 56.2 23.7 7.7Astotal (mg m�3) 23.3 7.5 56.6 28.1 9.2

PM2.5 and PM10. The Atlantic air masses and the rainfallthat usually occurs during these episodes produces a selec-tive washout of the mineralogical phases containing theAs(V), and also may produce a preferential dissolution ofAs(V) (e.g. oxide), which is too soluble to become an impor-tant solid phase in an aqueous environment (Sadiq et al.,1983). This process is confirmed by the higher As(III)/As(V) ratio determined for PM10 with respect to PM2.5 giventhat the coarser particles are preferentially scavenged bywashout. The undepleted concentrations of As(V) may bedue to its partition between vapour and fine particle phaseduring their transport from emission sources to the moni-toring station (Thomaidis et al., 2003).

5. Conclusions

In the city of Huelva, arsenic species [As(III) and As(V)]are concentrated in the fine size fraction (PM2.5), account-ing for 61–91% of PM2.5 in PM10. Peaks of As species andother metals (e.g. Cu, Zn, Pb, Se) in PM2.5 occur under SWwind regimes and during the impact of the emissions ofnearby copper smelter.

The annual mean of arsenic concentration determinedin PM10 in the city of Huelva during 2001–2002 slightlyexceeds the mean annual 6 ng m�3 target value proposedby the European Commission for 2013 (EU, 2004). Fromthis perspective, Huelva is considered to be one of themost polluted regions in arsenic in particulate matter inSpain and Europe. We have highlighted the importance ofarsenic speciation in studies of aerosol chemistry due tothe presence of arsenic species [As(III) and As(V)] with dis-tinct toxicity, and the further implications in future EU AirQuality Directives and that the As(III)/As(V) may be consid-ered as a fingerprint of the origin of the particulate matter,similar to isotope ratios.

Acknowledgements

We would like to thank the Spanish Ministry of theEnvironment, Department of Science (Project SIMAND-P07RNM-02729), and the Department of Environmentfrom Junta de Andalucıa for financing the study. We wouldalso like to thank the NOAA Air Resources Laboratory (ARL)for the provision of the HYSPLIT transport and dispersionmodel. Also thanks NASA/Goddard Space Flight Centre,Laboratory for Atmospheres, Greenbelt (Maryland, USA),the Atmospheric Modelling and Weather ForecastingGroup from the University of Athens, and the SeaWIFS pro-ject from NASA home page for the valuable information

episodes group, as well as mean PM10 levels by Sanchez-Rodas et al. (2007)

tbreakþAnthropogenic Atlantic advection

2.5 (n¼ 8) PM10 (n¼ 29) PM2.5 (n¼ 31) PM10

Min. Max. Mean Mean Min. Max. Mean

20 32 46 19 7 33 340.3 2.4 1.7 1.1 0.1 2.6 1.85.2 13.5 8.6 1.1 0.0 4.3 1.57.0 13.6 10.6 2.2 0.8 6.0 2.9

Fig. 4. Diagram of As(III)/As(V) in PM2.5 vs. As(III)/As(V) in PM10 for anthro-pogenic, Atlantic advection, and anthropogenic plus African outbreakepisodes in the period 2001–2002.

A.M. Sanchez de la Campa et al. / Atmospheric Environment 42 (2008) 6487–64956494

supplied by the SKIRON aerosol maps and the satelliteimages.

References

Adame, J.A., 2005. Caracterizacion y comportamiento del ozono superficialen la provincia de Huelva. Ph.D. thesis, University of Huelva, p. 291.

Alastuey, A., Querol, X., Plana, F., Viana, M., Ruiz, C.R., Sanchez de laCampa, A., de la Rosa, J., Mantilla, E., Garcıa dos Santos, S., 2006.Identification and chemical characterisation of industrial PM sourcesin SW Spain. Journal of Air Waste Management 56, 993–1006.

Davis Jr., R.A., Welty, A.T., Borrego, J., Morales, J.A., Pendon, J.G., Ryan, J.G.,2000. Rio Tinto estuary (Spain) 5000 years of pollution. Environmen-tal Geology 39, 1107–1116.

Draxler, R.R., Rolph, G.D., 2003. HYSPLIT (HYbrid Single-Particle Lagrang-ian Integrated Trajectory) Model. access via NOAA ARL READYWebsite. NOAA Air Resources Laboratory, Silver Spring, MD. http://www.arl.noaa.gov/ready/hysplit4.html.

Duker, A.A., Carranza, E.J.M., Hale, M., 2005. Arsenic geochemistry andhealth. Environment International 31, 631–641.

EU., 1999. 1999/30/CE Council Directive relating to limit values for sulphurdioxide, nitrogen dioxide and oxide of nitrogen, particulate matterand lead in ambient air. The Council of the European Union.

EU., 2004. 2004/107/CE Council Directive relating to arsenic, cadmium,mercury, nickel and polycyclic aromatic hydrocarbons in ambientair. The Council of the European Union.

European Commission., 2000. Air Pollution by As, Cd and Ni compounds.Working Group on As, Cd and Ni compounds Position Paper. VersionFinal, October 2000. DG Environment, EC, p. 361.

Farinha, M.M., Slejkovec, Z., Van Eltern, J.T., Wolterbeek, H.Th., Freitas, M.C., 2004. Arsenic speciation in coarse and fine airborne particles.Journal of Atmospheric Chemistry 49, 343–353.

Fernandez Espinosa, A.J., Ternero Rodriguez, M., Barragan de la Rosa, F.J., Jimenez Sanchez, J.C., 2001. Size distribution of metals in urbanaerosols in Seville (Spain). Atmospheric Environment 35 (14),2595–2601.

Francesconi, K.A., Kuehnelt, D., 2003. In: Frankenberger, W.T. (Ed.),Environmental Chemistry of Arsenic. Marcel Dekker, New York.

Grande, J.A., Borrego, J., Morales, J.A., 2000. A study of heavy metalpollution in the Tinto–Odiel estuary in southwestern Spain usingfactor analysis. Environmental Geology 39, 1095–1101.

Gidhagen, L., Kahelin, H., Schmidt-Thome, P., Johansson, C., 2002. Anthro-pogenic and natural levels of arsenic in PM10 in Central and NorthernChile. Atmospheric Environment 36, 3803–3817.

Gomez-Ariza, J.L., Sanchez-Rodas, D., Giraldez, I., Morales, E., 2000.A comparison between ICP–MS and AFS detection for arsenic specia-tion in environmental samples. Talanta 51, 257–268.

Gotschi, T., Hazenkamp, M.E., Heinrich-von-Arx, J., Bono, R., Burney, P.,Forsberg, B., Jarvis, D., Maldonado, J., Norback, D., Stern, W.B.,Sunyer, J., Toren, K., Verlato, G., Villani, S., Kunzli, N., 2005. Elementalcomposition and reflectance of ambient fine particles at 21 Europeanlocations. Atmospheric Environment 39, 5947–5958.

Hayes, R.B., 1997. The carcinogenicity of metals in humans. Cancer Causesand Control 8, 371–385.

Hedberg, E., Gidhagen, L., Johansson, C., 2005. Source contributions toPM10 and arsenic concentrations in Central Chile using positivematrix factorization. Atmospheric Environment 39 (3), 549–561.

Herman, J.R., Bhartia, P.K., Torres, O., Hsu, C., Seftor, C., Celarier, E., 1997.Global distribution of UV-absorbing aerosols from Nimbus7/TOMSdata. Journal of Geophysical Research 201, 16911–16922.

Kallos, G., Kotroni, V., Lagouvardos, K., 1997. The regional weatherforecasting system SKIRON: an overview. Proceedings of the Sympo-sium on Regional Weather Prediction on Parallel Computer Environ-ments. University of Athens, Greece, pp. 109–122.

Mandal, B.K., Suzuki, K.T., 2002. Arsenic round the world: a review.Talanta 58, 201–235.

McClain, C.R., Cleave, M.L., Feldman, G.C., 1998. Science quality SeaWiFSdata for global biosphere research. Sea Technology 39 (9), 10–16.

Oliveira, V., Gomez-Ariza, J.L., Sanchez-Rodas, D., 2005. Extraction proce-dures for chemical speciation of arsenic in atmospheric total sus-pended particles. Analytical Bioanalytical Chemistry 382, 335–340.

Pershagen, G., Lind, B., Bjorklund, N.E., 1982. Lung retention and toxicityof some inorganic arsenic compounds. Environmental Research 29,425–434.

Putaud, J.P., Raes, F., Fan Dingenen, R., Bruggemann, E., Facchini, M.C.,Decesari, S., Fuzzi, S., Gehrig, R., Huglin, C., Laj, P., Lorbeer, G.,Maenhaut, W., Mihalopoulos, N., Muller, K., Querol, X., Rodrıguez, S.,Schneider, J., Spindler, G., Ten Brink, H., Tøorseth, K.,Wiedensohler, A., 2004. A European aerosol phenomenology – 2:chemical characteristics of particulate matter at kerbside, urban, ru-ral, and background sites in Europe. Atmospheric Environment 38,2579–2595.

Querol, X., Alastuey, A., Rodriguez, S., Plana, F., Ruiz, C.R., Cots, N.,Massague, G., Puig, O., 2001. PM10 and PM2.5 source apportionmentin the Barcelona metropolitan area, Catalonia, Spain. AtmosphericEnvironment 35, 6407–6419.

Querol, X., Alastuey, A., de la Rosa, J., Sanchez de la Campa, A., Plana, F.,Ruiz, C.R., 2002. Source apportionment analysis of atmosphericparticulates in an industrialised urban site in southwestern Spain.Atmospheric Environment 36, 3113–3125.

Querol, X., Alastuey, A., Rodrıguez, S., Viana, M.M., Artinano, B.,Salvador, P., Mantilla, E., Garcıa do Santos, S., Fernandez Patier, R.,de la Rosa, J., Sanchez de la Campa, A., Menendez, M., GilIbarguichi, J.I., 2004a. Levels of particulate matter in rural, urbanand industrial sites in Spain. Science of the Total Environment334–335, 359–376.

Querol, X., Alastuey, A., Rodrıguez, S., Viana, M.M., Artinano, B.,Salvador, P., Mantilla, E., Garcıa do Santos, S., Fernandez Patier, R.,de la Rosa, J., Sanchez de la Campa, A., Menendez, M., GilIbarguichi, J.I., 2004b. Speciation and origin of PM10 and PM2.5 inSpain. Journal of Aerosol Science 35, 1151–1172.

Querol, X., Minguillon, M.C., Alastuey, A., Monfort, E., Mantilla, E., Sanz, M.J., Sanz, F., Roig, A., Renau, A., Felis, C., Miro, J.V., Artinano, B., 2007.Impact of the implementation of PM abatement technology on theambient air levels of metals in a highly industrialised area. Atmo-spheric Environment 41, 1026–1040.

Querol, X., Alastuey, A., Moreno, T., Viana, M.M., Castillo, S., Pey, J.,Rodrıguez, S., Artinano, B., Salvador, P., Sanchez, M., Garcia DosSantos, S., Herce Garraleta, M.D., Fernandez-Patier, F., Moreno-Grau, S., Negral, L., Minguillon, M.C., Monfort, E., Sanz, M.J., Palomo-Marın, P., Pinilla-Gil, E., Cuevas, E., de la Rosa, J., Sanchez de laCampa, A., 2008. Spatial and temporal variations in airborne particulatematter (PM10 and PM2.5) across Spain 1999–2005. AtmosphericEnvironment 42, 3964–3979.

Roy, P., Saha, A., 2002. Metabolism and toxicity of arsenic: a human car-cinogen. Current Science 82 (1), 38–45.

Rudnick, R.L., Gao, S., 2003. The crust. In: Holland, H.D., Turekian, K.K. (Eds.),Treatise of Geochemistry, vol. 3. Elsevier–Pergamon, Oxford, pp. 1–64.

Sadiq, M., Zaidi, T.H., Mian, A.A., 1983. Environmental behaviour of arsenicin soils: theoretical. Water, Air and Soil Pollutant 20, 369–377.

Sanchez de la Campa, A., 2004. Geochemistry of atmospheric particulatematter (APM) of Huelva, southwest of Spain. Ph.D. thesis, Universityof Huelva, p. 283.

Sanchez de la Campa, A., de la Rosa, J., Querol, X., Alastuey, A., Mantilla, E.,2007. Geochemistry and origin of PM10 at rural background site insouthwestern Spain. Environmental Research 103, 305–316.

Sanchez-Rodas, D., Geiszinger, A., Gomez-Ariza, J.L., Francesconi, K.A.,2002. Determination of an arsenosugar in oyster extracts by liquidchromatography–electrospray mass spectrometry and liquid chroma-tography-ultraviolet photo-oxidation-hydride generation atomicfluorescence spectrometry. Analyst 127, 60–65.

Sanchez-Rodas, D., Sanchez de la Campa, A.M., de la Rosa, J.D., Oliveira, V.,Gomez Ariza, J.L., Querol, X., Alastuey, A., 2007. Arsenic speciation of

A.M. Sanchez de la Campa et al. / Atmospheric Environment 42 (2008) 6487–6495 6495

atmospheric particulate matter (PM10) in an industrialised urban sitein southwestern Spain. Chemosphere 66, 1485–1493.

Slejkovec, Z., Salma, I., Van Elteren, J.T., Zemplen-Papp, E., 2000. Specia-tion of arsenic in coarse and fine urban aerosols using sequential ex-traction combined with liquid chromatography and atomicfluorescence detection. Fresenius Journal of Analytical Chemistry366 (8), 830–834.

Thomaidis, N.S., Bakeas, E.B., Siskos, P.A., 2003. Characterization of lead,cadmium, arsenic and nickel in PM2.5 particles in the Athens atmo-sphere, Greece. Chemosphere 52, 959–966.

Viana, M., Querol, X., Gotschi, T., Alastuey, A., Sunyer, J., Forsberg, B.,Heinrich, J., Norback, D., Payo, F., Maldonado, J.A., Kunzli, N., 2007.Source apportionment of ambient PM2.5 at five Spanish centres ofthe European community Respiratory Health Survey (ECRHS II).Atmospheric Environment 41, 1395–1406.

Viraraghavan, T., Jin, Y.C., Tonita, P.M., 1992. Arsenic in water supplies.International Journal of Environmental Studies 41, 159–167.

WHO (World Health Organization), 2001. Air Quality Guidelines forEurope, second ed. WHO Regional Publications, Regional Office forEurope, Copenhagen, Denmark.