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Atmospheric Environment 44 (2010) 2563e2576

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Atmospheric Environment

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Physicochemical variations in atmospheric aerosols recorded at sea onboardthe AtlanticeMediterranean 2008 Scholar Ship cruise (Part II): Natural versusanthropogenic influences revealed by PM10 trace element geochemistry

Teresa Moreno a,*, Noemi Pérez a, Xavier Querol a, Fulvio Amato a, Andrés Alastuey a,Ravinder Bhatia b,c, Baruch Spiro d, Melanie Hanvey b, Wes Gibbons e

a Institute of Environmental Assessment and Water Research, IDAEA, CSIC, C/Jordi Girona 18, Barcelona 08034, Spainb Formerly with The Scholar Ship Research Institute, London, UKcUK National Oceanography Centre, Southampton, UKdDepartment of Mineralogy, NaturalHistory Museum, Cromwell Road, London SW7 5BD, UKeAP 23075, Barcelona 08080, Spain

a r t i c l e i n f o

Article history:Received 1 December 2009Received in revised form6 April 2010Accepted 13 April 2010

Keywords:PM10 trace element chemistryMarine aerosolsAir pollution at sea

* Corresponding author.E-mail address: teresa.moreno@idaea.csic.es (T. M

1352-2310/$ e see front matter � 2010 Elsevier Ltd.doi:10.1016/j.atmosenv.2010.04.027

a b s t r a c t

The geochemistry of PM10 filter samples collected at sea during the Scholar Ship AtlanticeMediterranean2008 research cruise reveals a constantly changing compositional mix of pollutants into the marineatmosphere. Source apportionment modelling using Positive Matrix Factorization identifies NorthAfrican desert dust, sea spray, secondary inorganic aerosols, metalliferous carbon, and VeNi-bearingcombustion particles as the main PM10 factors/sources. The least contaminated samples show an uppercontinental crust composition (UCC)-normalised geochemistry influenced by seawater chemistry, withmarked depletions in Rb, Th and the lighter lanthanoid elements, whereas the arrival of desert dustintrusions imposes a more upper crustal signature enriched in “geological” elements such as Si, Al, Ti, Rb,Li and Sc. Superimposed on these natural background aerosol loadings are anthropogenic metal aerosols(e.g. Cu, Zn, Pb, V, and Mn) which allow identification of pollution sources such as fossil fuel combustion,biomass burning, metalliferous industries, and urbaneindustrial ports. A particularly sensitive tracer isLa/Ce, which rises in response to contamination from coastal FCC oil refineries. The Scholar Ship databaseallows us to recognise seaborne pollution sourced from NW Africa, the Cape Verde and Canary islands,and European cities and industrial complexes, plumes which in extreme cases can produce a downwinddeterioration in marine air quality comparable to that seen in many cities, and can persist hundreds ofkilometres from land.

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1. Introduction

The monitoring and collection of aerosols during the AtlanticeMediterranean voyage of Oceanic II “The Scholar Ship” (http://en.wikipedia.org/wiki/The_Scholar_Ship) in MarcheApril 2008provided an opportunity to study atmospheric particulate mattercontinuously from the equatorial Atlantic to the English Channel,including a detour across theMediterranean to Istanbul. This paper isthe second ina two-part series: inPart I (Pérez et al., inpress)wehavereported on the variations in hourly PM10, PM2.5, and PM1 particlesize fraction concentrations and main components (marine, crustal,carbon, secondary inorganic compounds) during this voyage. The

oreno).

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most influential types of atmospheric contamination identified wereNorth African dust (NAF), sea spray, and plumes emanating fromvarious sources including biomass burning, port cities, and industrialsulphate clouds. In this secondpaperwe focus on the chemistryof thesame samples of aerosols collected at sea, with emphasis on the useof trace elements to distinguish between natural and anthropogenicsources of PM10 encountered in the marine atmospheric environ-ment. The data cover a wide range of atmospheric conditions whichincluded clean air above calm ocean, “calima” desert dust haze at sea(both in the Atlantic and Mediterranean), spray-saturated daysduring heavy seas, and marine air polluted bymajor industries, largecities, and biomass burning smoke drifting out to sea. Our analysis isof relevance not only to the many studies investigating the influenceof trace elements on marine biogeochemical processes, but also tomodelling of desert dust intrusions, coastal industrial-port pollutionplumes, and temporalespatial variations in PM concentrations at sea

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e25762564

(e.g. Begum et al., 2004; Koçak et al., 2004; Jickells et al., 2005;Engelstaedter et al., 2006; Verma et al., 2007; Bhanuprasad et al.,2008; Jiménez-Vélez et al., 2009).

2. Methodology

Aerosol levels and chemical composition measurements wereperformed onboard of Oceanic II-The Scholar Ship from 9th Marchto 19th April 2008. The sampling was performed during the voyagebetween and in the following ports: Cape Town, Sao Vicente (CapeVerde Islands), Barcelona, Istanbul, Lisbon and Amsterdam. Adetailed description of the methodology for sampling, analysingPM samples and characterising atmospheric scenarios is shown inthe Supplementary Information. Weather conditions were takenfrom the data set of meteorological measurements, recorded threetimes a day while at sea, as part of the World MeteorologicalOrganization Voluntary Observing Ship (VOS) Scheme (http://www.vos.noaa.gov/vos_scheme.shtml, Table S1 in SupplementaryInformation).

A source apportionment analysis of the PM10 data was carriedout by means of a Positive Matrix Factorization (PMF; Paatero andTapper, 1994) through the Multilinear Engine programminglanguage (ME-2; Paatero,1999) with the objective of identifying themain PM sources and their contribution along the journey. The PMFfit was performed over 31 days of the journey, and excluded thosedays in which the cruise was idling at harbours. Application of PMFmethodology to ship-based observations has already been testedby Bhanuprasad et al. (2008). The PMFmethod is based on themassconservation principle:

xij ¼Xp

k¼1

gik fjk þ eij i ¼ 1;2;.;m j ¼ 1;2;.;n (1)

where xij is the jth species concentration measured in the ithsample, gik is the contribution of the kth source to the ith sample, fjkis the concentration of the jth species in the kth source and eij is theresidual associated with the jth species concentration measured inthe ith sample. The task of PMF is to minimize the sum of thesquares of the residuals weighted inversely with the estimateduncertainties. Chemical species were selected based on the Signalto Noise ratio, the percentage of values above detection limit and tothe database size requirements. Factors are classified taking intoaccount several diagnostic criteria: i) PMF-resolved chemicalprofile; ii) the variation explained for every species by each factors(specific tracers can be identified); iii) the time-evolution ofcontribution, in relation with the position of the cruise.

3. Results

The dominant influences on the chemistry of the airborne PMcollected during the voyage are revealed in Fig. 1 which normalisesthe four main chemical components (crustal, sea spray, secondaryinorganic aerosols (SIA) and total carbon) to PM10 mass. The PM10mass values and chemical analyses of the PM10 filters onwhich thisfigure is based are shown in Tables 1a and 1b, and the samechemical data but normalised to PM10 mass are presented inTable S2 in Supplementary Information. Fig. 1 illustrates the majorelement chemical signature of the pollution events identified in ourprevious paper (Part I) and provides a starting point for thegeochemical investigation presented below. Specifically, thepollution events revealed on Fig. 1 include two North African desertdust intrusions (NAF1: 12Mare18Mar, NAF2: 10Apre12Apr), threesea spray peaks associated with headwinds and/or heavy seas(19Mare20Mar, 29Mar, 17Apr), and elevated C levels associatedwith pollution from coastal cities (27Mar, 1Apr, 7Apr, 15e16Apr).

Peaks of SIA concentrations coincide with entry into far-travelled(Central European-sourced) industrial pollution clouds in theAegean Sea (31Mar, 9Apr) and English Channel (18e19Apr), andmore locally derived (Iberian Peninsula) pollution when the shipwas sailing close to Spain and Portugal (19e21Mar, 13e16Apr:Fig. 1).

The results from the source apportionment show an excellentcorrelation between the mass calculated by the PMFmodel and theactual gravimetric measurements of PM10 (slope¼ 0.99 andr2¼ 0.99). The distribution of the scaled residuals and the G-spaceplots were also used as diagnostic criteria, providing satisfactoryresults. Fig. 2 displays the identified source profiles, the explainedvariation of each species by each factor, and the temporal variationsduring the voyage. The PMF model recognises the same four majorfactors (crustal-African dust, sea spray, SIA and carbon) identifiedby the chemical data (Fig. 1), and these together account for thebulk of the sampled PM. The carbonaceous factor is also charac-terised by enrichments in several trace metals, notably Zn, Cu andSb (Fig. 2a). In addition the PMF analysis recognises a fifth factorcharacterised by high VeNi emissions (Fig. 2a). There is generallya good fit between Figs.1 and 2: the two NAF events are particularlywell defined. The PMF model recognises most (but not all) of thehigh-SIA events, and the days when sea spray was dominant(Fig. 2b). The major peaks in carbonaceous emissions are linked toport visits, especially Barcelona and Istanbul, and the largest VeNianomaly is also associated with Istanbul port (Fig. 2): the traceelement character and significance of these two anthropogenicemission factors are further investigated later in this paper. Sourcecontributions were investigated dividing the data set into threemain stages of the cruise journey: Stage 1 (Equatorial Atlantic tothe Moroccan coast), Stage 2 (Eastward Mediterranean Traverse)and Stage 3 (IstanbuleLisboneEnglish Channel). Chemicalmeasurements were generally well reproduced, with correlationcoefficients higher than 0.88. The VeNi emissions factor permittedto estimate the total amount of PM10 emitted by fuel-oil/refineryactivities, resulting in 0.3, 0.8 and 2.1 mgm�3, respectively forStage 1, Stage 2 and Stage 3 (Table S3 in SupplementaryInformation). Sea spray emissions were revealed to be aroundtwice the sum of Na and Cl�, due to some contribution of sulphateand nitrate. African dust was better reproduced within the Medi-terranean (Stages 2 and 3) than in the Atlantic (Stage 1). Themetalliferous carbon factor followed the (0.5�OC )þ( 0.37� EC)pattern, but revealed a total emission around three times higherdue to the presence of non-C atoms and other compounds. FinallySecondary aerosol factor reproduced SIA concentrations in Stage 2and 3, while in Stage 1 most of SIA was attributed to other sources.Comparing our PMF interpretation with that of Bhanuprasad et al.(2008), who analysed a similar database obtained during a cruiseacross the Indian Ocean in 1999, we note a similar recognition ofcrustal dust (their “Si-dust”), SIA, and zinc-bearing carbonaceousfactors, but our model does not recognise factors for biomassburning or “Ca-dust”. Biomass smoke assumed importance onlybriefly during the campaign (passing sub-Saharan Africa), andexposure to calcareous dust was similarly transient, occurringduring the passage through NAF2 close to Tunisia (see below).

Our next step is to examine the chemical data in more detail,and in order to achieve this we repeat the approach taken in Part 1(Pérez et al., in press) by dividing the voyage into three stages. Thefirst of these follows the ship north from the equatorial East Atlanticto the NW Moroccan coast (9e19Mar) and involved 10 days at seawith a brief stop in at Sao Vicente in the Cape Verde Islands. Thesecond leg is the Eastward Mediterranean Traverse from theGibraltar Straits to Turkey via a stop in Barcelona (7 days at sea:19e21Mar and 27Mare1Apr). The last stage comprises the journeyback west from Istanbul then north to the English Channel, an

Fig. 1. Concentrations of crustal, sea spray, carbonaceous, and secondary inorganic PM10 in 24-h filter samples obtained during the Scholar Ship cruise from the equatorial Atlanticto the English Channel. The main events influencing PM10 composition were two North African dust intrusions (NAF), high sea spray contents during heavy seas, industrial sulphateclouds drifted from central Europe and Iberia, and pollution associated with large city ports. Data are normalised to PM10 mass (see Table S2 Supplementary Information). Thechemical composition recorded during initial conditions in the open Atlantic on 9e10 March (sample 10Mar), when the ship was sailing more than 1400 km from Africa and withPM10 measuring <10 mgm�3, is described as that of calm ocean clean air (COCA).

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e2576 2565

11-day journey (7e18Apr) which included a day stopover in Lisbon.The following sections examine the results from each of thesestages, focussing in particular on tracer elements characteristic ofeither natural (marine or crustal) or anthropogenic PM sources inthe open sea.

3.1. Stage 1. Equatorial Atlantic to the Moroccan coast

The monitoring campaign began in the open Atlantic some1400 km off the Angolan coast in clean air characterised by verylow PM concentrations (<10 mgm�3 PM10). Element concentrationsunder these conditions are corresponding very low (sample10Mar), and when the data are normalised to PM10 mass the fourmajor chemical components (crustal, sea spray, SIA, total carbon)have broadly similar values (Fig. 1). This narrow range of massnormalised values containing all four components in calm oceanclean air (COCA on Fig. 1) represents the lowest atmosphericcontamination recorded during the voyage. Trace elements simi-larly record very low mass values for sample 10Mar which, in thecase of Li, V, Ni, Sr and Pb are dataset minima (Table 1a).

The progressive change in sample chemistry during this first legof the voyage, from COCA conditions on 9e10th March northwardsthrough a major North African dust intrusion (NAF1) to theMoroccan coast is recorded in Fig. 3. The steady rise of crustalparticle concentrations over the first three days (Fig. 3a) is mirroredby that of the elements (excluding Na) that we have selected onFig. 3b, namely Al, Ti, Li, Rb and Sc. These may be considered typical“geogenic” elements, residing almost exclusively in upper crustalrock forming minerals, mostly in felsic silicates such as micas,feldspars and non-mafic clays, but also in small resistant accessoryminerals such as oxides and phosphates. We have added concen-trations of Na to Fig. 3b primarily to illustrate changes in sea sprayconcentrations, which showed a marked increase once the shipencountered NE trade winds (sample 13Mar). Also Na concentra-tions do not show the rapid decline exhibited byall crustal elementsupon exit fromNAF1 (sample 18Mar), but insteadmaintain elevatedlevels as the ship sailed against northerly headwinds (Fig. 3b).

Taken together, the crustal and marine elements plotted inFig. 3b record natural influences on atmospheric PM chemistry. Incontrast, Fig. 3c selects elements more typical of pollution fromurbaneindustrial-biomass combustion sources and these

consequently show relatively little or no initial increase inconcentration while the ship remained far from the African main-land (samples 10e12Mar). Upon entry simultaneously into NAF1and a biomass burning smoke plume sourced from sub-SaharanNW Africa, when the ship was some 500 km from Sierra Leone(sample 13Mar), levels of all elements show a marked increase(Table 1a). Much of this increase is a direct result of the influx ofcrustal desert dust, as concentrations of PM10 jump from 23 to82 mgm�3 in one day. However, some trace metals such as Cu, Sb,Zn and Cr are anomalously high, an increase which, along withhigher C levels, we attribute to the presence of the sub-Saharanbiomass smoke plume. This chemical signature is also identified bythe PMF model, shown as an increase in metalliferous carbon(Fig. 2b, sample 13Mar). Concentrations of Cu, Sb and Zn (but not Asor Pb) return to previous levels after the ship had passed throughthe smoke plume and moved away from the African coast towardsthe Cape Verde Islands (Figs. 2b, 3c, sample 14Mar).

By the afternoon of 14th March The Scholar Ship was passingthrough the southern (Sotavento) archipelago of the Cape VerdeIslands, and PM10 levels rise transiently to >65 mgm�3. The PMfilter sample including this encounter with Cape Verde-sourcedaerosols (sample 15Mar) shows no appreciable change in crustalPM concentrations, but a marked rise in anthropogenic contami-nants (Figs. 3bec). Themost extreme increases are shown by Pb, As,Sn, and Mn, with notable rises also in Sb, Ge, Ga, Zn, Co, Fe, and K.This sample (15Mar) contains atmospheric concentrations of Pb,Mn, Fe, K, Ga, Ge, Co higher than at anytime later during the voyage,even those measured in ports such as Istanbul. Indeed, Pbconcentrations registered at sea on 14e15Mar samples arecomparable to those currently being measured in highly pollutedurban land areas such as the centre of Mexico City (Moreno et al.,2008a). Presumably the ship passed through a metalliferousindustrial smoke plume emanating from one of the nearby islands,and once again the event is recognised in the PMF model (Fig. 2b,sample 15Mar).

Much of the following day was spent moored in Porto Grande onSao Vicente Island in the northern (Barlovento) Cape Verde archi-pelago, still under the influence of NAF1 and with no appreciablechange in crustal element concentrations and OMþ EC (sample16Mar: Table 1a and Fig. 3b). Given the absence of the metalliferousplume recorded in the Sotavento Islands, the concentration of most

Table 1aMajor (mgm�3) and trace (ngm�3) element analyses determined by means of ICP-AES and ICP-MS.

1a

Date 10-mar 11-mar 12-mar 13-mar 14-mar 15-mar 16-mar 17-mar 18-mar 19-mar 20-mar 21-mar 27-mar 28-mar 29-mar

mgmL3 9.1 13.2 22.8 82.4 57.9 66.9 74.6 52.0 45.5 10.4 19.2 19.7 22.1 27.8 39.5OC 0.6 0.5 1.0 2.5 1.2 1.7 1.9 0.6 0.9 0.4 0.9 1.7 3.2 2.4 1.8EC 0.1 0.1 0.2 0.4 0.1 0.3 0.3 0.1 0.2 <d.l. 0.2 0.2 1.2 0.6 0.4CO3

¼ 0.2 0.3 0.5 6.0 3.7 3.4 3.7 2.0 1.7 0.2 0.3 0.5 1.8 0.9 0.5SiO2 0.7 2.0 6.4 21.2 18.3 15.8 21.6 12.9 10.1 0.3 0.1 0.3 1.6 0.5 <0.1Al2O3 0.2 0.7 2.1 7.1 6.1 5.3 7.2 4.3 3.4 0.1 0.0 0.1 0.5 0.2 <0.1Ca 0.1 0.2 0.4 4.0 2.5 2.3 2.4 1.4 1.1 0.2 0.2 0.4 1.2 0.6 0.3K 0.1 0.2 0.3 1.2 1.0 1.4 1.2 0.8 0.7 0.1 0.2 0.2 0.2 0.2 0.3Na 0.5 1.2 1.4 7.3 4.4 5.2 4.8 4.7 4.6 2.7 4.2 3.2 0.9 3.8 6.9Mg 0.1 0.2 0.3 1.7 1.2 1.2 1.4 1.0 0.9 0.3 0.5 0.4 0.2 0.4 0.8Fe 0.1 0.2 0.6 2.3 2.0 3.8 2.4 1.3 1.1 0.0 0.0 0.1 0.4 0.1 0.2SO4

2- 1.0 1.6 1.4 5.9 3.2 3.2 4.4 4.6 6.3 1.7 3.1 2.7 1.5 2.8 4.2NO3

- 0.3 0.5 0.6 1.4 1.3 1.2 1.6 2.1 3.5 0.7 2.0 3.1 2.6 1.7 3.2Cl- 0.3 0.8 1.0 5.1 2.9 5.9 4.9 4.4 3.3 2.8 4.1 2.5 0.7 4.0 10.4NH4

þ <0.1 <0.1 <0.1 0.1 <0.1 0.1 0.1 0.2 0.4 <0.1 0.3 0.4 0.2 0.2 0.4

Crustal 1.4 3.8 10.7 43.6 34.8 33.2 39.9 23.7 18.8 1.3 1.3 1.9 5.9 2.9 2.1Sea spray 0.9 2.0 2.4 12.4 7.3 11.1 9.7 9.1 7.9 5.5 8.3 5.7 1.6 7.8 17.3SIA 1.4 2.1 2.0 7.4 4.5 4.5 6.0 6.9 10.3 2.4 5.3 6.2 4.3 4.7 7.7ECþOM 1.0 1.0 1.8 4.5 2.1 3.0 3.4 1.1 1.6 1.6 3.0 6.4 4.4 3.3

ngmL3

P 5.6 8.7 19.0 67.8 51.1 62.6 66.1 33.9 36.8 3.8 28.0 9.9 16.9 18.0 12.2Li 0.1 0.2 0.5 2.3 2.2 2.1 2.7 1.6 1.4 0.1 0.1 0.1 0.3 0.2 0.2Sc <0.1 0.1 0.2 0.8 0.7 0.6 0.8 0.4 0.3 <d.l. <d.l. <d.l. <0.1 <d.l. <d.l.Ti 8.4 25.7 74.1 236.5 177.4 173.8 240.7 132.0 106.7 4.3 2.3 5.2 18.4 10.5 2.5V 0.4 0.9 2.1 10.7 7.4 6.8 17.6 7.8 12.7 2.0 12.5 2.8 10.5 13.6 16.8Cr <d.l. <d.l. <d.l. 21.5 7.0 0.6 0.2 <d.l. 1.0 <d.l. 4.2 4.0 <d.l. <d.l. <d.l.Mn 1.3 4.3 10.5 43.4 31.9 151.4 40.1 21.6 16.6 0.7 1.0 2.1 11.0 3.2 2.5Co 0.1 0.1 0.3 1.5 0.9 1.6 1.2 0.6 0.6 0.0 0.1 0.1 0.2 0.2 0.3Ni 0.8 1.0 0.8 13.3 2.7 6.2 7.5 3.0 4.6 0.8 4.7 1.3 4.5 6.7 7.6Cu 3.0 2.2 2.4 91.6 4.4 36.0 13.4 4.0 4.2 3.8 2.1 2.7 18.7 9.1 3.6Zn 3.2 1.5 2.4 40.5 4.4 57.9 33.2 3.2 11.8 5.2 5.8 14.7 59.3 20.2 2.3Ga <0.1 0.1 0.4 1.2 1.0 2.1 1.4 0.7 0.6 <0.1 <0.1 <0.1 0.1 0.1 <0.1As 0.1 0.1 0.3 0.9 1.0 10.1 5.3 0.6 0.8 0.1 0.2 0.3 0.4 0.4 0.3Se 0.2 0.1 0.2 0.5 0.6 0.6 0.6 0.7 1.0 0.3 0.4 0.6 0.5 0.6 0.6Rb 0.2 0.4 1.2 4.4 3.6 3.5 4.4 2.5 2.2 0.1 0.1 0.2 0.5 0.3 0.2Sr 0.9 2.1 4.2 31.7 21.2 19.3 23.8 14.6 10.9 1.9 3.0 2.7 2.6 3.3 5.1Y 0.1 0.2 0.5 1.7 1.3 1.1 1.4 0.8 0.7 <d.l. 0.1 <0.1 0.2 0.1 0.1Zr 5.1 7.7 12.3 17.6 15.9 15.2 16.4 13.6 13.3 4.0 0.3 9.9 9.8 10.5 9.9Nb 0.1 0.3 0.9 2.5 1.7 1.6 2.0 1.2 1.0 0.1 0.1 0.2 0.2 0.2 0.1Mo <d.l. <d.l. <d.l. 9.1 0.8 1.6 <d.l. <d.l. <d.l. <d.l. 0.2 <d.l. <d.l. <d.l. <d.l.Cd <0.1 <0.1 <0.1 0.1 <0.1 0.1 0.9 <0.1 0.1 <0.1 <0.1 0.1 0.1 0.1 0.1Sn 0.1 0.2 0.1 1.1 0.3 7.6 2.2 0.3 0.5 0.1 0.2 0.7 4.3 2.2 0.6Sb <d.l. <d.l. <d.l. 1.1 0.1 2.2 0.6 <0.1 0.5 <d.l. 0.1 0.2 2.7 0.7 0.8Cs <d.l. <d.l. 0.1 0.2 0.2 0.2 0.2 0.1 0.1 <d.l. <d.l. <d.l. 0.0 <d.l. <d.l.Ba 1.5 10.8 18.5 49.1 31.1 48.6 43.5 26.3 16.1 2.7 16.2 18.6 22.2 30.2 <d.l.La 0.08 0.22 0.71 2.28 1.78 1.46 1.99 1.16 0.97 0.03 0.13 0.06 0.22 0.17 0.21Ce 0.20 0.57 1.76 5.74 4.50 3.80 5.03 2.92 2.42 0.06 0.13 0.10 0.45 0.26 0.16Pr 0.02 0.06 0.18 0.57 0.45 0.37 0.50 0.29 0.24 0.01 0.01 0.01 0.04 0.02 0.01Nd 0.09 0.24 0.77 2.50 1.97 1.63 2.19 1.29 1.06 0.03 0.05 0.05 0.16 0.09 0.03Sm 0.02 0.06 0.16 0.50 0.39 0.33 0.43 0.25 0.22 0.01 0.02 0.02 0.04 0.03 0.02Eu <d.l. <d.l. 0.04 0.09 0.08 0.07 0.08 0.06 0.05 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.Gd 0.03 0.05 0.15 0.46 0.36 0.30 0.38 0.24 0.19 0.01 0.03 0.01 0.05 0.05 0.02Tb <d.l. 0.01 0.02 0.06 0.04 0.04 0.05 0.03 0.03 <d.l. <d.l. <d.l. 0.01 0.01 <d.l.Dy 0.03 0.05 0.11 0.33 0.26 0.21 0.28 0.17 0.14 0.01 0.03 0.02 0.05 0.06 0.03Ho <d.l. 0.01 0.02 0.06 0.05 0.04 0.05 0.03 0.03 <d.l. <d.l. <d.l. 0.01 0.01 <d.l.Er 0.01 0.02 0.05 0.14 0.11 0.09 0.13 0.07 0.06 <d.l. 0.01 <d.l. 0.02 0.02 0.01Tm <d.l. <d.l. <d.l. 0.04 0.03 0.03 0.04 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.Yb 0.01 0.02 0.05 0.16 0.12 0.10 0.14 0.08 0.08 <d.l. 0.01 <d.l. 0.02 0.01 0.01Lu <d.l. <d.l. <d.l. 0.03 <d.l. <d.l. 0.03 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.Hf 0.12 0.24 0.43 0.61 0.54 0.51 0.53 0.46 0.46 0.06 <d.l. 0.34 0.36 0.34 0.37Ta <d.l. <d.l. <d.l. 0.06 0.05 0.05 0.05 0.04 0.03 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.W <d.l. <d.l. 0.09 0.23 0.07 0.22 0.19 0.02 0.06 <d.l. <d.l. 0.07 0.07 <d.l. <d.l.Tl <d.l. <d.l. <d.l. 0.04 0.03 0.04 0.04 <d.l. <d.l. <d.l. <d.l. 0.03 0.06 0.11 <d.l.Pb 0.4 0.7 1.1 5.2 4.7 141.3 36.1 4.1 19.9 0.4 5.9 4.1 10.9 4.5 2.7Bi <d.l. <d.l. <d.l. 0.06 <d.l. 0.07 0.04 0.03 0.04 <d.l. <d.l. 0.05 0.28 0.22 0.04Th 0.01 0.07 0.25 0.84 0.67 0.55 0.71 0.42 0.36 <d.l. <d.l. <d.l. 0.07 0.03 0.03U 0.07 0.07 0.12 0.35 0.28 0.21 0.24 0.17 0.18 0.02 0.13 0.05 0.13 0.16 0.10

La/Ce 0.39 0.39 0.40 0.40 0.40 0.38 0.40 0.40 0.40 0.46 1.05 0.62 0.48 0.66 1.26

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e25762566

Table 1bMajor (mgm�3) and trace (ngm�3) element analyses determined by means of ICP-AES and ICP-MS.

Date 30-mar 31-mar 01-apr 07-apr 08-apr 09-apr 10-apr 11-apr 12-apr 13-apr 14-apr 15-apr 16-apr 17-apr 18-apr 19-apr

mgmL3

PM10 22.1 27.3 38.2 29.5 30.7 27.2 50.0 101.7 30.1 13.1 18.3 21.6 26.4 26.1 37.9 32.2OC 1.7 2.9 7.8 5.1 3.3 1.3 1.0 2.6 0.8 0.7 1.5 3.3 3.3 1.0 1.8 2.8EC 0.3 0.6 1.4 3.2 0.6 0.3 0.3 0.3 0.1 0.1 0.3 0.9 0.7 0.2 0.4 0.6CO3

¼ 0.4 0.5 0.8 1.1 0.4 1.0 3.1 8.3 1.3 0.3 0.4 1.0 0.5 0.4 0.5 0.4SiO2 0.3 1.3 3.5 2.3 0.6 2.0 11.7 33.6 5.3 0.3 0.4 1.1 1.0 0.3 0.7 0.7Al2O3 0.1 0.4 1.2 0.8 0.2 0.7 3.9 11.2 1.8 0.1 0.1 0.4 0.3 0.1 0.2 0.2Ca 0.3 0.3 0.6 0.7 0.2 0.7 2.1 5.6 0.9 0.2 0.3 0.7 0.3 0.2 0.3 0.3K 0.2 0.3 0.5 0.2 0.2 0.2 0.7 1.8 0.4 0.1 0.2 0.2 0.2 0.2 0.2 0.2Na 3.3 2.5 0.5 1.4 1.8 2.8 3.5 3.3 3.2 2.6 2.2 1.5 1.1 5.3 4.2 1.4Mg 0.4 0.3 0.2 0.3 0.2 0.4 0.9 1.8 0.6 0.3 0.3 0.2 0.2 0.6 0.5 0.2Fe 0.1 0.2 0.5 0.4 0.1 0.2 1.2 3.2 0.6 0.1 0.1 0.2 0.3 <0.1 0.1 0.3SO4

2- 2.9 5.8 5.7 4.4 4.7 4.8 4.8 5.4 2.3 2.3 3.4 2.8 4.3 3.5 3.6 4.5NO3

- 2.7 2.4 3.5 1.1 2.6 4.2 5.2 6.6 2.4 2.9 3.0 3.0 5.1 1.3 8.5 7.9Cl- 2.5 1.1 0.4 1.5 1.2 1.5 3.1 3.3 3.8 1.7 1.8 0.9 0.4 7.6 5.3 2.0NH4

þ 0.2 0.6 1.3 0.5 0.8 0.5 0.3 0.1 0.1 0.2 0.4 0.4 1.1 0.2 1.5 2.1

Crustal 1.8 3.4 7.2 5.9 2.0 5.2 23.6 65.5 10.7 1.5 1.7 3.9 2.8 1.8 2.7 2.2Sea spray 5.8 3.6 0.8 2.9 3.0 4.3 6.6 6.6 7.0 4.4 3.9 2.4 1.5 13.0 9.6 3.4SIA 5.8 8.8 10.5 6.0 8.0 9.4 10.4 12.2 4.7 5.3 6.8 6.3 10.4 5.0 13.6 14.5ECþOM 2.9 5.2 13.9 11.4 5.9 2.4 1.9 4.4 1.4 1.3 2.7 6.1 6.0 1.7 3.3 5.1

ngmL3

P 10.1 12.6 25.8 21.0 8.5 16.0 29.8 73.3 17.6 8.1 12.1 25.7 19.5 8.9 14.7 24.8Li 0.1 0.3 0.5 0.3 0.1 0.3 1.6 4.6 0.7 0.1 0.1 0.2 0.2 0.2 0.2 0.2Sc <d.l. <0.1 0.1 0.1 <d.l. <0.1 0.4 1.2 0.2 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.Ti 5.0 18.0 52.0 27.8 6.5 20.5 122.6 344.3 56.2 4.3 6.8 14.2 18.7 3.5 8.5 8.4V 5.0 3.7 12.7 78.2 19.3 10.7 17.8 39.7 7.4 5.9 24.8 17.1 31.9 21.8 3.2 6.8Cr 2.0 2.5 1.0 4.3 6.0 4.4 6.3 9.4 3.9 8.8 8.3 11.8 13.7 4.7 4.9 5.3Mn 1.5 5.9 14.1 9.5 2.8 3.5 18.5 52.2 15.6 1.2 2.7 6.2 4.6 1.3 5.1 9.8Co 0.1 0.1 0.3 0.4 0.1 0.1 0.5 1.4 0.3 0.1 0.2 0.3 0.3 0.1 0.1 0.1Ni 2.0 1.7 4.4 21.5 6.5 3.3 5.6 9.9 2.4 1.9 8.3 6.3 11.3 5.6 1.5 3.4Cu 5.1 4.1 7.6 15.9 3.7 2.1 2.8 4.7 2.8 2.9 3.3 10.2 8.3 1.7 3.3 5.0Zn 6.1 19.6 41.1 39.4 19.7 10.1 11.9 15.0 4.3 6.1 9.3 29.3 27.1 4.0 15.1 30.2Ga <0.1 0.1 0.3 0.2 0.1 0.1 0.6 1.7 0.3 <0.1 0.1 0.1 0.1 <0.1 0.1 0.1As 0.3 0.6 1.3 1.6 2.7 0.3 0.7 1.3 0.4 0.2 0.5 1.0 0.7 0.2 0.3 0.6Se 0.7 0.9 1.0 0.5 0.8 0.9 1.0 1.2 0.7 0.7 0.9 1.2 1.6 0.6 1.0 1.2Rb 0.2 0.7 1.7 0.6 0.3 0.5 2.5 7.1 1.1 0.1 0.2 0.5 0.5 0.2 0.4 0.5Sr 2.6 2.6 3.1 3.5 1.5 5.1 15.1 37.1 6.0 2.2 1.8 2.0 1.8 3.6 3.2 1.8Y <d.l. <d.l. 0.5 0.1 <d.l. 0.2 0.8 2.0 0.3 0.1 <d.l. <0.1 0.2 <d.l. <0.1 <0.1Zr 8.7 10.0 14.1 6.0 6.7 9.5 13.9 18.6 11.3 8.4 9.0 5.0 12.2 9.9 4.8 3.4Nb 0.1 0.2 0.5 0.3 0.2 0.3 1.2 2.9 0.6 0.1 0.1 0.2 0.3 0.1 0.2 0.2Mo <d.l. <d.l. 5.0 <d.l. <d.l. 0.9 2.8 1.2 <d.l. 0.2 <d.l. <d.l. 0.2 <d.l. <d.l. <d.l.Cd 0.1 0.3 0.8 1.4 0.2 0.1 0.1 0.1 <0.1 <0.1 0.1 0.2 0.2 <0.1 0.1 0.2Sn 0.7 0.5 1.2 1.4 0.6 0.3 0.3 0.5 0.2 0.2 0.7 1.4 2.3 0.6 0.9 1.1Sb 0.3 0.4 1.9 2.1 1.0 0.2 0.4 0.8 0.3 0.1 0.2 1.0 0.8 0.3 0.5 0.6Cs <d.l. 0.1 0.2 0.1 <d.l. <0.1 0.2 0.4 0.1 <d.l. <d.l. <0.1 <d.l. <d.l. <0.1 0.1Ba 0.8 2.6 <d.l. 16.1 <d.l. 25.4 30.4 46.8 6.9 6.5 <d.l. 18.7 35.2 <d.l. 15.3 12.8La 0.07 0.17 0.43 0.43 0.10 0.20 1.19 2.98 0.48 0.07 0.18 0.31 0.30 0.09 0.15 0.13Ce 0.09 0.31 0.87 0.70 0.11 0.45 2.78 7.36 1.12 0.10 0.12 0.24 0.30 0.08 0.16 0.19Pr 0.01 0.03 0.09 0.06 0.01 0.05 0.28 0.74 0.11 0.01 0.01 0.02 0.03 0.01 0.02 0.02Nd 0.04 0.14 0.40 0.27 0.06 0.20 1.24 3.27 0.50 0.05 0.05 0.11 0.14 0.03 0.08 0.08Sm 0.01 0.02 0.10 0.06 0.01 0.05 0.25 0.65 0.10 0.01 0.01 0.03 0.03 0.01 0.02 0.02Eu <d.l. <d.l. 0.03 <d.l. <d.l. <d.l. 0.05 0.11 0.03 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.Gd 0.01 0.02 0.11 0.04 0.01 0.04 0.23 0.56 0.08 0.02 <d.l. <d.l. 0.04 <d.l. 0.01 0.01Tb <d.l. <d.l. 0.02 0.01 <d.l. 0.01 0.03 0.07 0.01 <d.l. <d.l. <d.l. 0.01 <d.l. <d.l. <d.l.Dy 0.01 0.01 0.10 0.04 0.02 0.06 0.18 0.40 0.07 0.02 <d.l. 0.02 0.06 0.01 0.02 0.02Ho <d.l. <d.l. 0.02 0.01 <d.l. 0.01 0.03 0.07 0.01 <d.l. <d.l. <d.l. 0.01 <d.l. <d.l. <d.l.Er <d.l. 0.01 0.04 0.02 0.01 0.02 0.08 0.18 0.03 0.01 <d.l. <d.l. 0.02 <d.l. 0.01 0.01Tm <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. 0.05 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.Yb <d.l. 0.01 0.04 0.02 0.01 0.02 0.09 0.21 0.03 0.01 <d.l. <d.l. 0.02 <d.l. 0.01 0.01Lu <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. 0.04 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.Hf 0.29 0.34 0.57 0.18 0.20 0.42 0.55 0.68 0.48 0.32 0.37 0.14 0.45 0.43 0.13 0.07Ta <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. 0.05 0.13 <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l. <d.l.W <d.l. <d.l. 0.10 0.05 0.02 0.03 0.08 0.19 0.03 0.03 0.03 0.07 0.18 0.02 0.07 0.15Tl 0.05 0.06 0.15 0.04 0.07 <d.l. 0.08 0.07 <d.l. <d.l. <d.l. 0.02 <d.l. <d.l. 0.03 0.11Pb 2.7 9.4 35.7 10.9 8.6 3.4 5.7 22.0 7.8 2.1 3.6 8.3 7.2 1.2 5.7 12.1Bi 0.04 0.06 0.10 0.11 0.07 0.03 0.05 0.04 <d.l. <d.l. 0.06 0.15 0.16 0.03 0.11 0.18Th <d.l. <d.l. 0.20 0.09 <d.l. 0.11 0.48 1.17 0.19 0.03 <d.l. <d.l. 0.08 0.02 0.01 <d.l.U 0.03 <d.l. 0.21 0.09 0.07 0.11 0.23 0.36 0.08 0.07 <d.l. 0.07 0.15 0.03 0.05 0.06

La/Ce 0.79 0.53 0.49 0.61 0.90 0.45 0.43 0.40 0.43 0.65 1.52 1.27 0.99 1.10 0.89 0.70

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e2576 2567

V-Ni emissions

Sea spray

African dust

Metalliferous

carbon

emissions

0

4

8

12

051015

2025

3035

40

0102030405060708090100

0

5

10

15

20

0

10

20

30

Al 2O

3

Ca

Na

Ti

La

Ce

V Ni

Cu

Zn

Sb

Pb

SO

4

NO

3Cl

NH

4

+

OC

EC

00,10,20,30,40,50,60,70,80,91

Secondary aerosols

00,10,20,30,40,50,60,70,80,91

Metalliferous carbon emissions

00,10,20,30,40,50,60,70,80,91

African dust

00,10,20,30,40,50,60,70,80,91

Sea spray

0,0001

0,001

0,01

0,1

10,0001

0,001

0,01

0,1

1

0,0001

0,001

0,01

0,1

1

0,0001

0,001

0,01

0,1

10,0001

0,001

0,01

0,1

1

00,10,20,30,40,50,60,70,80,91

Concentration Explained variation

Secondary

aerosols

19-a

pr18

-apr

17-a

pr16

-apr

15-a

pr14

-apr

13-a

pr12

-apr

11-a

pr10

-apr

9-ap

r8-

apr

7-ap

r1-

apr

31-m

ar30

-mar

29-m

ar28

-mar

27-m

ar21

-mar

20-m

ar19

-mar

18-m

ar17

-mar

16-m

ar15

-mar

14-m

ar13

-mar

12-m

ar11

-mar

10-m

ar

MP ot noitubirtnoC

01m/gµ( slevel

3 )

noitairav denialpxE

)gµ/gµ( noitartnecnoC

Barcelona Istanbul

ba

C

ape

Verd

e

C

anar

y Is

.

refin

ery

(Spa

in)

refin

ery

(Ital

y)

refin

ery

(Spa

in)

NAF1

NAF2

Lisbonbiomass

Cape Verde

fuel

-oil

V-Ni emissions

Fig. 2. Positive Matrix Factorization (PMF) results indicating the five factors identified by the model. a: Chemical profile for each factor showing concentration histograms and theexplained variation for each element. b: Time series plots illustrating changing contributions of each PMF factor during the ship voyage.

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e25762568

anthropogenic trace elements decline in sample 16Mar, althoughremainingmore abundant than in the open seas south of Cape Verde.The chemical cocktail is different, however, with V, Ni and Cdshowing increases in contrast to decreases in Pb, Cu, Zn, As, Sb, Sn, Gaand Ge (Table 1a, sample 16Mar). The increase in V and Ni content ofthis port sample is recognised in the VeNi factor of the PMF model(Fig. 2b) and ascribed to shipping fuel oil emissions.

Departure from Sao Vicente Island resulted in a decline in theanthropogenic PM content, with levels of metals falling to thoseprior to entry into the Cape Verde archipelagos (comparethe similarity between samples 14Mar and 17Mar on Figs. 2b and3b). This decline was interrupted once more by entry into anaerosol plume downwind of the Canary Islands, when PM10 rose to

around 50 mgm�3 for 10 h. Once again there was a rise in anthro-pogenic trace elements indicating plume arrival, with notableincreases in atmospheric Pb, Sb, and Zn (Fig. 3c, sample 18Mar) andthe PMF VeNi factor (Fig. 2b). Another influence of this plumewas to raise concentrations of both carbon and SIA (Fig. 3a) inresponse to anthropogenic atmospheric pollution from sourcessuch as traffic, port activities and industrial emissions includingpower generation. By midday on the following day, winds wereblowing once again from the open sea, the ship had cruised north ofNAF1, and PM10 levels fell below 20 mgm�3. Under these conditions,and with a freshening northerly headwind, concentrations ofcarbon, SIA and (especially) crustal elements fell drastically, and forthe first time Na from sea spray becomes strongly dominant

a

b

c

Fig. 3. Journey from the Equatorial Atlantic to the Moroccan coast. 24-h PM10 filter sample chemical data showing variations in: a. crustal, sea spray, secondary inorganiccompounds (SIA), ECþOM (elemental carbon and organic matter); b. crustal (Al, Ti, Li, Rb, Sc) and marine (Na) elements; c. variations in trace metalliferous contaminants showingpeaks coincident with entry into pollution plumes from biomass burning in sub-Saharan Africa, metalliferous industry in Cape Verde (Sotavento Archipelago), and the CanaryIslands.

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e2576 2569

(Fig. 3a, b, sample 19Mar). Most metalliferous trace elements alsodecline, although some (e.g. Pb, Sb) more than others (e.g. Cu, Zn)(Fig. 3c, sample 19Mar).

3.2. Stage 2: Eastward Mediterranean Traverse

This second phase, passing through the Gibraltar Straits andeastwards across the Mediterranean, began some 75 km offshorefrom Casablanca, with fresh headwinds and much sea spray duringthe journey to Barcelona. Most element concentrations increasealong with PM mass during this first part of the journey, and Naremains dominant (samples 20e21Mar on Fig. 4). Trace elementconcentrations normalised to PM10 mass indicate unusually highlevels of P and U during the first day (Table S2 in SupplementaryInformation, sample 20Mar), suggesting atmospheric contamina-tion from the phosphate industries of western Morocco (e.g.Gaudry et al., 2007) and/or SW Spain (Bolívar et al., 2008). Massnormalised Cr levels are also higher than normal (Table S2 inSupplementary Information, samples 20e21Mar), indicating the

presence of another industrial PM point source, the most likelyorigin in this case being emissions from industry around the Bay ofAlgeciras where there is a major petrochemical complex whichincludes the largest oil refinery in Spain (San Roque: capacity240,000 b/d), as well as an oil fired power station and a majorsteelworks (Querol et al., 2007). A more subtle indicator of indus-trial contamination is the rise in La/Ce ratio from normal crustalvalues of around 0.4 to >1 in sample 20Mar (Table 1a), this beinga clear signal of anthropogenic La enrichment (Olmez and Gordon,1985; Moreno et al., 2008b). This spike in La/Ce value coincideswith the ship passing close to the San Roque refinery, which layupwind of The Scholar Ship during passage through the GibraltarStraits. Such refineries use La in their fluid catalytic converter (FCC)systems and are well-documented sources of atmospheric La(Kulkarni et al., 2007; Moreno et al., 2008c). The VeNi factor rec-ognised in the PMF calculation also rises once more during thispassage through the Gibraltar Straits (Fig. 2b). Finally, anotherindication of changing contamination patterns is the increase in Znconcentrations relative to other anthropogenically-sourced metals

b

c

a

Fig. 4. Journey during Eastward Mediterranean Traverse. 24-h PM10 filter sample chemical data showing variations in: a. crustal, sea spray, secondary inorganic compounds (SIA),ECþOM (elemental carbon and organic matter); b. crustal (Al, Ti, Li, Rb, Sc) and marine (Na) elements; c. anthropogenic trace metal enhancements coincident with entry intopollution plumes from biomass burning (13Mar), industrial plumes from Cape Verde Islands (15Mar), and S Spain (Gibraltar area: 20Mar and 14Apr).

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e25762570

such as Pb and Cu (Fig. 4c). From entry of the ship into the Medi-terranean and onwards throughout the remaining journey, Zn is tobecome the most abundant anthropogenic trace metal present inmost of the samples collected.

During the stay in Barcelona port there is a predictable fall in seaspray particles and a rise in crustal (resuspension), tracemetals, andcarbonaceous (traffic and possibly smoke) PM10, although thesewere suppressed well below normal city levels by wet weather(Table 1a, Figs. 1e4, sample 27Mar). These urbaneindustrial traceelement enrichments decline on departure from Barcelona andduring the 2-day crossing in rough seas to the coast of Sicily PM10

levels other than those sourced fromsea sprayare very low. The PMFdata show a very strong NaCl peak, initially high VeNi, and very lowmetalliferous carbon factor as Barcelona city is left behind (Fig. 2b).The relatively high VeNi factor in the PMF data in this case may bedue to locally sourced fuel oil smoke contamination from the ship’sfunnel because weather conditions at this time resulted in a strongfollowing wind (from the NW), making contamination of theequipment placed on the bowof the vesselmore likely than in otherdays during the voyage.

The most interesting chemical features registered during thispart of the journey are renewed peaks in La/Ce (this timereaching 1.26) and the VeNi PMF factor, this time during thevoyage from Menorca to Sicily (Table 1a, sample 29Mar; Fig. 2b).This LaþVþNi enrichment is once again coincident with theship passing downwind of a major FCC oil refinery: the Sarrochcomplex in S Sardinia, which is not only the largest in Italy butone of the few integrated refinery-petrochemical supersites inEurope (capacity 300,000 b/d). Lanthanum enrichment continuesto be higher than normal (double crustal values) in the samplecollected the following day (Table 1b, sample 30Mar), as the shipsailed downwind of another FCC oil refinery at Gela (capacity100,000 b/d) on the southern Sicilian coast (Bosco et al., 2005).We did not observe evidence of the Etna volcanic plume, prob-ably due to strong winds and the transient nature of anyencounter with this pollution source.

Sea conditions during this eastward Mediterranean crossingreduced from initially rough (west of Sardinia) to moderate (Sicily)and, on the approach to Greece, light. As a result, the amount of seaspray collected on filters was already in decline by the morning of

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e2576 2571

30th March and continued progressively to fall on the remainingjourney to Istanbul, whereas most other chemical componentsbegan to rise (Fig. 4). A particularly prominent rise in secondarysulphate and nitrate records entry into the Central European-source industrial plume identified in Part I of this study (supportedby identification tools such as NAAPS aerosol maps) and wellillustrated by the PMF data (Fig. 2b, samples 30Mare1Apr). Arrivalin Istanbul is also accompanied by a strong PMF metalliferouscarbon peak (Fig. 2b), with exceptionally high levels of PM10 andelevated trace metal concentrations (Zn, V, Ni, Cr, Cu, Cd, Sn, Sb, W,Tl, Pb and Bi: Table 1b; Fig. 4c, sample 1Apr).

3.3. Stage 3: IstanbuleLisboneEnglish Channel

An anomalously high spike in V and Ni highlighted by the PMFmodel for 7th April suggests significant but transient contaminationby shipping fuel oil combustion in Istanbul port just prior todeparture (Fig. 2b, sample 7Apr). Once at sea however PM10 levelsand most trace element concentrations immediately fell, but beganto rise during the traverse across the Aegean Sea as the ship

Fig. 5. Journey from Istanbul to the English Channel. 24-h PM10 filter sample chemical daECþOM (elemental carbon and organic matter); b. crustal (Al, Ti, Li, Rb, Sc) and marine (N

re-entered the fringes of the central European sulphate cloud (Pérezet al., in press) and a now southerly wind introduced the first waveof African desert dust intrusion NAF2 (Fig. 5). The PM10 chemistryanalysed from filters during NAF2 is similar to NAF1, with an over-whelming dominance of crustal particles and low levels of anthro-pogenic tracer elements. One difference in major elementgeochemistry is that during the height of NAF2 (Table 1b, sample11Apr) the sample collected is more calcareous than at anytimeduring NAF1, explaining the brief rise in the PMF carbonaceouscomponent coincident with NAF2 (Fig. 2b, sample 11Apr). Differ-ences in the calcareous content of African dust intrusions in theMediterranean have been observed by other authors (e.g. Querolet al., 2009) and attributed to variations in the geology of sourceareas. In the case of The Scholar Ship measurements a similarexplanation is likely: for example, Quaternary calcareous sedimentslie upwind of the ship’s passage close to the coast of NE Tunisia atthis time. With regard to trace element compositions, as with themajor elements there are some differences between the two NAFevents (e.g. higher V and Pb during NAF2), but overall they arechemically extremely similar (compare Figs. 3 and 5).

a

b

c

ta showing variations in: a. crustal, sea spray, secondary inorganic compounds (SIA),a) elements; c. variations in anthropogenic trace metals.

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e25762572

Following exit from NAF2 levels of crustal PM fall to concen-trations not seen since the similar exit from NAF1, again undermoderate headwinds in open seas (Table 1; Figs. 3e5). On thesubsequent approach back to the Gibraltar Straits, concentrations ofSIA and VeNi emissions rose (Fig. 2b sample 14Apr) along withseveral other anthropogenic tracer elements. Cobalt, Mn, Sn and Laall more than double in concentration from 13th Apr to 14th Apr,despite only modest rises in total PM10 mass (Table 1b). Prominentincreases in V, Ni and La also characterised the eastward traversethrough the Gibraltar Straits some weeks earlier (sample 20Mar),and similarly once again there is a marked increase in La/Ce whichjumps from crustal values of 0.4 during NAF2 to 1.52 close toGibraltar (Table 1b). Levels of La stay relatively elevated as the shipprogressed around SW Iberia parallel to the Portuguese coast, andconcentrations of SIA and VeNi emissions are also high (Table 1b,Fig. 2b), especially when normalised to PM10 mass (Table S2 inSupplementary Information). This clearly anthropogenic signal isinterpreted as due to following (southerly) winds failing to dispersethe effect of Iberian industrial pollution, combined with further FCCcontamination from another nearby major oil refinery complex atSines (200,000 b/d) en route for Lisbon.

The trace element chemistry of PM10 collected during the briefstay in the Port of Lisbon is characterised by a renewed increase incrustal (resuspended) PM and a strongly anthropogenic tracemetal signature, with emphasis on higher Cr, Cu and Ba concen-trations, and a renewed peak in the PMF VeNi factor linked to portemissions (Fig. 2b, sample 16Apr). There is also a notable increasein P content (especially obvious when concentrations are nor-malised to PM10 mass: Table S2 in Supplementary Information),a likely source for which derives from the Barreiro-Lavradiophosphate industry on the south Tagus estuary opposite the cityand upwind during the visit (Carvalho, 1995). Following thedeparture from Lisbon, however, levels of all PM components fellto previous open sea concentrations, with the exception of seaspray which assumed dominance during the rough crossingaround NW Spain (Figs. 2b and 5a). Finally, arrival of The ScholarShip into the English Channel was coincident with entry into a far-travelled but still prominent industrial sulphate cloud broughtwest from central Europe, as detailed in Part I of this study (Pérezet al., in press). Under these conditions SIA concentrations rise totheir highest value recorded during the voyage, accompanied bya general rise in pollutant trace metals such as Pb, Cd, Zn, Ni andMn (Table 1b; Figs. 2b and 5c).

Fig. 6. Summary of metalliferous pollution events identified during The Scholar Ship voya(La/Ce> 1) atmospheric aerosol plumes from coastal FCC oil refineries in Gibraltar, Sardini

4. Discussion and conclusions

The main anthropogenic pollution events recorded at sea andrevealed by the 24-h chemical data are summarised in Fig. 6 whichnormalises concentrations of Cu, Pb, Zn, Mn, V and P to PM10 mass,and shows La/Ce (�10) to identify FCC refinery contamination. Thefirst four of these events (1e4 on Fig. 6) were superimposed uponalready high concentrations of PM10 during NAF1 and each ischaracterised by a distinctive cocktail of metalliferous PM. Thebiomass burning smoke haze encountered on 12e13th March(event 1) contained unusually high contents of Cu and Zn (but notPb or Mn), in contrast to the industrial emissions encountered inthe Sotavento archipelago of the Cape Verde Islands which induceprominent increases in all four of these metals but a relativedecrease in V (Fig. 6, sample 15Mar, event 2). The next day,however, thesemetals fell in concentrationwhereas V rose to a newpeak during a 12-h stay in port (Fig. 6, sample 16Mar, event 3).Following departure from the Cape Verde Islands the data recorda return to NAF conditions uncontaminated by anthropogenicpollution until the plume drifting south from the Canary Islands ismarked by a renewed increase in the concentrations of severalmetals, notably Pb and Zn (Fig. 6, sample 18Mar, event 4).

The peaks in P content observed from the journeys inward (east)from NW Morocco to S Spain, and outward (west) from S Spain toSW Portugal (events 5 and 10, Fig. 6) suggest an influence from theimportant coastal phosphate industries present all these threecountries, although the exact source, whether from SW of Casa-blanca, Huelva, and/or near Lisbon, remains uncertain. The pollu-tion associated with passage through the Gibraltar Straits (events 5and 9, Fig. 6) is, however, more easily pinpointed as on both inwardand outward journeys the normalised data show increase in V, La,Ni, and Cr (Table S2 in Supplementary Information). The Gibraltararea is a known contamination hotspot for pollution by theseelements, due primarily to metallurgical and petrochemicalindustries in the La LineaeAlgeciras areas (Querol et al., 2007), aswell as fuel oil contamination from congested shipping lanes. TheLa/Ce ratio measured in the Gibraltar Straits deviates so far abovenormal crustal values that contamination from the Gibraltar-SanRoque FCC oil refinery is clearly the most likely source, a deductionstrongly reinforced by similar atmospheric lanthanoid anomalies(La/Ce> 1) spatially associated during the voyage with refineryemissions in Sardinia (Sarroch), Sicily (Gela) and SW Portugal(Sines) (Fig. 6).

ge, with chemical data normalised to PM10 mass. The La/Ce line registers La-enricheda, Sicily and SW Portugal (see text for discussion).

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e2576 2573

The value of La/Ce as a measure of atmospheric contaminationby FCC refinery complexes is further demonstrated in Fig. 7a.Triangular diagrams such as Fig. 7 are commonly used to illustratecompositional variations in lithospheric minerals and rocks, andcan equally be employed to illustrate geochemical patterns inatmospheric PM (e.g. Moreno et al., 2006a). Fig. 7a plots La, Ce andSm, with concentrations adjusted to place crustal abundances ofthese elements in the centre of the triangle. Whereas NAF samplesreveal their uncontaminated nature by plotting near the centre ofthis triangle within the compositional field of common rockforming minerals, several of the non-NAF samples are shiftedtowards La. These La-contaminated samples correspond to thosecollected when the ship had passed through refinery pollutionplumes from Spain, Italy and Portugal, with the most extremecontamination being shown by sample 14Apr, collected close to theGibraltar-San Roque refinery and comparable in composition to

a

b

Fig. 7. Three-component diagrams illustrating trace element variations in the Scholar Ship 24compositions. Lanthanum enrichments are produced by contamination from FCC oil refinerySines in SW Portugal (15e18Apr). The sample from Istanbul (8Apr) is attributed to La-bearingcompositions of common rocks and silicate minerals (see Moreno et al., 2008c). Urban ambien(2001: Delft), and Kowalczyk et al. (1982: Washington), and Moreno et al. (2008c: Puertollanoet al. (1992); b. LaRbZn plot showing trend from UCC compositions to increasingly anthropogsamples most contaminated by refinery emissions from Gibraltar and Sardinia deviate away

urbaneindustrial La-contaminated PM samples reported on land(Fig. 7a). Another demonstration of the La enrichment of ourrefinery-contaminated samples from Gibraltar (20Mar and 14Apr)and Sardinia (29Mar) is demonstrated in Fig. 7b. On this figure thecrustal element Rb is compared with La and Zn, revealing ananthropogenic contamination line running from natural UCC/NAFcompositions towards Zn, and a discernable displacement towardsLa in the most refinery-influenced samples (Fig. 7b).

The PMF model in general agrees well with the pollution eventsrecognised in Figs. 1 and 6, although there are some exceptions: theelevated SIA concentrations recorded by the chemical data on11Apr, for example, are not recognised by the PMF model. Giventhat some major compounds (sulphate and carbon among others)are emitted by multiple sources the PMF proved useful in demon-strating and quantifying individual contributions of distinct sour-ces. The most useful additional data provided by PMF is the

-h filter samples: a. LaCeSm plot showing La enrichment trend away from natural crustalemissions from Gibraltar (20Mar, 14Apr), Sardinia (29Mar), Sicily (30Mar), and probablyfuel oil combustion. UCC¼Upper continental crustal composition. Grey ring representst lanthanoid PM data (1e3) obtained from Dzubay et al. (1988: Philadelphia), Wang et al.). Refinery, oil, and coal combustion lanthanoid data from Dzubay et al. (1988) and Kittoenic Zn contamination. Desert dust samples (NAF1 and 2) plot closest to UCC. The threefrom the main trend and are drawn towards the La apex.

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e25762574

recognition of carbonaceous and VeNi factors. The carbonaceousfactor is clearly mainly associated with atmospheric pollution inports visited during the voyage, but minor peaks in this factor arealso produced by biomass (13Mar) and industrial (15Mar) smokeplumes encountered at sea, as well as the arrival of naturallycalcareous desert dust sourced from limestones (11Apr). Theidentification of multiple components contributing to this factorserves as a reminder of the care needed in interpreting PMF data. In

a

c

b

Fig. 8. Multi-element diagram normalised to Upper Continental Crust (UCC) comparing 24-hwith relatively little contamination by anthropogenic metals and showing a broadly continlanthanoid (LOID) elements; b. Days when land-sourced dust is at a minimum and marine-sourelative to UCC; c. Filter samples (2 continental and 2 marine) contaminated by technogenic mplume), Cu (biomass burning plume), V (Gibraltar petrochemical complex), and P (phosphat

the case of the NieV factor, this is more clearly purely anthropo-genic in origin, coinciding with shipping emissions in ports andbusy shipping lanes, as well as hydrocarbon combustion plumesemanating from upwind petrochemical complexes passed duringthe voyage.

Finally, adopting awider perspective of our geochemical database,we can recognise the difference between dominantly continental,marine and anthropogenically contaminated PM10 samples collected

PM10 filter samples collected at sea during: a. Desert dust intrusions (NAF1 and NAF2)ental chemical signature for large ion lithophile (LILE), high field strength (HFSE) andrced PM assume dominance, producing marked depletion in LILE, Th and LOID elementsetal pollutants (and in one case P) showing peaks in Mn and Pb (Cape Verde Sotavento

e industry). Shaded area represents the compositional range of all 12 samples shown.

T. Moreno et al. / Atmospheric Environment 44 (2010) 2563e2576 2575

at sea by normalising the data to upper crustal composition ona multi-element plot (Fig. 8). We have ordered this diagram toillustrate variations in large ion lithophile elements (LILE, e.g. Rb, Sr),high field strength elements (HFSE, e.g. Zr, Hf, U, Nb, Th), the morecommon representatives of the lanthanoid group (La to Yb), P andcommon pollutant metals (Mn, V, Cu, Pb, Zn). Particulate mattersamples collected during NAF events (continental: Fig. 8a) showslight LILE depletion, a predictable consequence of the mobility andsusceptibility of these elements to chemical weathering. In contrast,HFSE are slightly enriched relative to UCC due to their tendency toconcentrate in small, chemically andphysically resistant atmosphericaccessory microminerals such as zircon, rutile, and monazite(Moreno et al., 2006b).

The geochemical depletion of atmospheric aerosols in LILE, andthe enrichment in Zr, Hf, and U, is more pronounced in PM samplescollected at sea away from desert dust intrusions, producing a verydifferent normalised multi-element pattern (marine: Fig. 8b). Suchsamples show depletion in both Th and lanthanoid elements,especially the lighter members of this group (LLoids: La to Nd inFig. 8b). These differences between UCC normalised NAF and non-NAF trace element ratios can be explained primarily by the greaterinfluence of seawater chemistry on those samples less influencedby terrestrial dust. Thus the distinctive trend of U enrichmentversus loss of Th is explicable because U is much more stable inseawater than is Th, which becomes attached to sinking particles,producing depletion relative to UCC (Poschl and Mollet, 2007).Similarly lighter lanthanoids such as Ce in seawater are depletedwith respect to the heavier group members such as Yb: UCC valuesfor Ce/Yb, for example, are ca. 23 whereas in ocean water they aretypically <10 (e.g. Greaves et al., 1999).

All samples are strongly enriched in metals compared to UCCconcentrations, even those collected on days when no specificcontamination plume was identifiable (e.g. 14th and 17th Mar).When locally sourced anthropogenic plumes contaminate marineair, however, there are pronounced deviations from normalbackground levels of some trace elements. The four samples onFig. 8c exemplify some of the results of such contamination,ranging from the Cu-rich biomass smoke recorded far from landin the central Atlantic (13Mar), to the MnePb industrial pollutionplume encountered in the Cape Verde Islands (15Mar), and theenrichments in P, La and V in the Gibraltar area (20Mar, 14Apr).Overall, our database offers a good illustration of the constantlychanging mix of land-sourced pollutants into the marine atmo-sphere. Whereas in our geochemical analysis we have found thetrace elements Rb, Sc, and Li most useful for identifying naturalinfluxes of continental (or “geological”) dust, it is several of themore toxic metals, notably Pb, Zn, Cu, Sb and Sn, which mostclearly reveal anthropogenic influences. These pollutants inextreme cases can produce a downwind deterioration in marineair quality comparable to that seen in many cities, and traces ofsuch plumes can remain easily detectable hundreds of kilometresfrom land.

Acknowledgements

This study has been financially supported by the SpanishMinistryof the Environment and the Plan Nacional de IþD from theMinistryof Education and Science (MMA 2006_EG0X2006-M-PARTICULADO-M1, GRACCIE: CONSOLIDER-INGENIO 2010 n� 22422, and CGL2007-62505/CLI (DOASUR)) and the European Union (6th frameworkCIRCE IP, 036961). The authors would also like to acknowledgeNASA/Goddard Space Flight Center, SeaWIFS-NASA Project, Univer-sity of Athens, Navy Research Laboratory e USA and the BarcelonaSuper-Computing Centre for their contribution with TOMS maps,satellite images, SKIRON dust maps, NAAPs aerosol maps, and

DREAM dust maps, respectively. The authors gratefully acknowledgethe NOAA Air Resources Laboratory (ARL) for the provision ofthe HYSPLIT transport and dispersion model and/or READY website(http://www.arl.noaa.gov/ready.html) used in this publication.We thank the owner, officers and crew of the Oceanic II (The ScholarShip) for their operational assistance. R. Bhatia, M. Hanvey and TheScholar Ship were financially supported by Royal Caribbean CruiseLines.

Appendix. Supplementary information

Supplementary data associated with this article can be found inthe online version at doi:10.1016/j.atmosenv.2010.04.027.

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