CHEMICAL CONTAMINANTS IN THE ARCTIC ENVIRONMENT – ARE THEY A CONCERN FOR WILDLIFE? BIRGITM. BRAUNE Environment Canada, Science and Technology Branch, National Wildlife Research Centre, Carleton University, 1125 Colonel By Drive (Raven Road), Ottawa, Ontario K1A 0H3 Canada E-mail: [email protected] ABSTRACT.—Environmental contaminants are a global problem, and their presence in the Arctic reflects the way in which the Arctic interacts with the rest of the world. Most contaminants are transported to the North on air and ocean currents from more southerly agricultural and industrial sources. Upon reaching the Arctic environment, many persistent contaminants bioaccumulate and biomagnify in the food web, making those species feeding at high trophic positions more vulner- able to contaminant exposure via their diet. By examining contaminant levels in wildlife, we can look for the arrival of new contaminants in the Arctic, as well as determine whether existing chem- ical contaminants of concern are increasing or decreasing. Historically, contaminants of concern included compounds such as the polychlorinated biphenyls (PCBs), and organochlorine pesticides such as dichlorodiphenyltrichloroethane (DDT). During the 1950s to 1970s, bioaccumulation of organochlorine compounds such as DDT and its degradation product, dichlorodiphenyl - dichloroethane (DDE), were associated with eggshell thinning and reduced reproduction rates in top predatory species such as the Peregrine Falcon (Falco peregrinus). The majority of these legacy persistent organic pollutants (POPs) have significantly declined in Arctic biota over the last several decades. However, more recently, newer compounds such as brominated flame retar- dants (BFRs) and perfluorinated compounds (PFCs) have been detected in a wide variety of biota including Arctic wildlife. Certain metals are also contaminating the Arctic environment. Elemental mercury (Hg0) is highly volatile, and gaseous Hg partitions readily into the atmosphere where it can undergo long-range atmospheric transport to the polar regions which are global sinks for Hg. Although Hg occurs naturally in the environment, anthropogenic sources have been postulated to contribute more significantly to the occurrence of Hg in the Arctic than natural emissions, result- ing in increasing Hg concentrations in a variety of Arctic biota, particularly in the Canadian Arctic and western Greenland. Recent warming ocean conditions and longer ice-free periods have also altered prey availability in some areas of the Arctic, affecting nutrition and chemical contaminant profiles. These changes in environmental conditions and contaminant exposure all contribute to the complexity of interpreting the contaminant profiles found in Arctic biota. Received 1 March 2011, accepted 19 April 2011. BRAUNE, B.M. 2011. Chemical contaminants in the Arctic environment–Are they a concern for wildlife? Pages 133–146 inR. T. Watson, T. J. Cade, M. Fuller, G. Hunt, and E. Potapov (Eds.). Gyrfalcons and Ptarmigan in a Changing World, Volume I. The Peregrine Fund, Boise, Idaho, USA. http://dx.doi.org/ 10.4080/ gpcw.2011.0114 Key words: Contaminants, POPs, mercury, Arctic, wildlife, climate change. 113333 –BRAUNE– BIOTAATNORTHERN LATITUDES are exposed to environment, while others enter the environ- a variety of chemical residues that are, for the ment through incomplete chemical reactions most part, transported there by the prevailing and destruction of the material. BFRs have winds, ocean currents and rivers (AMAP many chemical characteristics which make 2009). Unlike metals, such as mercury, persist- them behave in ways that are similar to POPs. ent organic pollutants are generated entirely Brominated organic compounds, such as poly- from anthropogenic sources (AMAP 2004). In brominated diphenyl ethers (PBDEs), addition to the legacy organochlorine contam- hexabromo cyclododecanes (HBCDs) and inants, such as the PCBs and DDT, other polybrominated biphenyls (PBBs), have been classes of chemical contaminants have been detected in a wide variety of biota including found more recently in the Arctic environment. Arctic wildlife (de Wit et al. 2006). The United These include the brominated flame retardants States is currently the only Arctic country pro- and perfluorinated compounds. ducing BFRs (de Wit et al. 2010). Of the three technical PBDE products (Penta-BDE, Octa- Legacy Persistent Organic Pollutants.—Per- BDE, Deca-BDE), Penta- and Octa-BDE were sistent organic pollutants (POPs), which have banned in the European Union and in Norway been banned or restricted in use, are generally in 2004, and the sole manufacturer of these referred to as legacy POPs. These include such two products in the United States voluntarily compounds as the polychlorinated biphenyls discontinued production in 2005 (de Wit et al. (PCBs), and organochlorine pesticides such as 2010). Production of PBBs has also ceased. As dichlorodiphenyltrichloroethane (DDT), its of 2008, however, there were no restrictions on break-down product dichlorodiphenyldichloro - the production and use of technical HBCD. ethane (DDE), chlordane, hexabromobenzene (HCB), hexachlorocyclohexane (HCH), and Perfluorinated Compounds.—Poly- and per- mirex. In response to regulatory actions to fluorinated organic compounds (PFCs) are reduce emissions (e.g. Stockholm Convention ubiquitous in the Arctic environment. on POPs, UN ECE Convention on Long-range Although PFCs were commercialized over 40 Transboundary Air Pollution (LRTAP) POPs years ago, they received little attention until Protocol), most of the legacy POPs have they were reported as contaminants in wildlife declined in the Arctic environment as reflected in the Arctic and elsewhere by Giesy and Kan- in time trends for air (Hung et al. 2010) and nan (2001). Since then, PFCs have been shown biota (Rigét et al. 2010). However, because of to be widespread in the environment and in their chemical characteristics, POPs will wildlife (Houde et al. 2006, Lau et al. 2007, remain in the environment for many decades Butt et al. 2010). The chemical and thermal to come. stability of PFCs has led to the manufacture of a range of fluoropolymers used as lubricants, Brominated Flame Retardants.—Brominated adhesives, stain and soil repellants, paper coat- flame retardants (BFRs) are chemicals used in ings, non-stick surfaces on cookware, and fire- materials to make them more fire-resistant. fighting foams (Kissa 2001). The major Examples include polyurethane foam, plastics fluorinated compounds that have been meas- used in electronic equipment, circuit boards, ured in the environment are the perfluorinated expanded and extruded plastic (e.g. Styro- sulfonates (PFSAs), of which perfluorooctane foam), and textile coatings (de Wit et al. 2010). sulfonate (PFOS) is best known, and the per- Most BFRs are additives mixed into polymers fluorinated carboxylates (PFCAs) which and are not chemically bound to the materials, include perfluorooctanoate (PFOA) (Butt et al. while others react chemically with the mate- 2010). Regulation of PFCs is being discussed rial. Those BFRs which are additives may sep- at both international and national levels, and arate/leach from surface of product into PFOS has recently been nominated as a candi- 134 –CHEMICALCONTAMINANTSINARCTICWILDLIFE– date POP for the UN ECE LRTAP POPs Pro- have found that many non-volatile but highly tocol (AMAP 2009) and, in 2009, was listed as stable compounds such as the highly bromi- a POP to be regulated for restricted use under nated compounds as well as the PFCAs and the Stockholm Convention (Stockholm Con- PFSAs are present in the Arctic (Muir and de vention on POPs 2010). Wit 2010). Their presence may be due to atmospheric transport on particles, or to degra- Mercury.—Although mercury (Hg) occurs nat- dation of volatile precursors. For the more urally in the environment, emissions from water-soluble, less volatile contaminants, human activities, such as fossil fuel combus- transport via ocean currents may be more tion, non-ferrous metal production, and waste important than the atmospheric route (Li et al. incineration, have been postulated to con- 2002, 2004). Unlike the atmospheric transport tribute more significantly to the occurrence of pathway, which can deliver contaminants from Hg in the Arctic than natural emissions mid-latitudes to the Arctic within a few days or (Pacyna 2005). The quantities of mercury weeks, ocean transport is relatively slow and it released from human activities have been may take decades before contaminants reach increasing over the past 200 years, i.e. since the Arctic (AMAP 2002). Waterborne contam- the Industrial Revolution (Nriagu and Pacyna inants may also enter Arctic marine ecosys- 1988, Pacyna et al. 2006). This has resulted in tems via northward-flowing rivers draining significant increases in biotic Hg levels over into the Arctic Ocean (Braune et al. 2005a). that time period, even in regions that are remote from most anthropogenic sources, such Unlike other POPs, the two main classes of as the Arctic (Dietz et al. 2006, 2009). PFCs found in the environment are not volatile Although there is not yet a global policy to and their transport pathways to the Arctic are reduce emissions of mercury, many countries complex. Two major potential pathways have are already taking steps to lower their emis- been proposed. One pathway focuses on sions. In 2003, a Protocol on Heavy Metals atmospheric transport of particles, or degrada- was adopted by the UN ECE LRTAP Conven- tion of volatile precursors to PFCAs in the tion aimed at limiting emissions of mercury atmosphere, and the second pathway involves and other metals from Europe and North the transport of directly-emitted PFCAs and America. PFSAs via ocean currents to the Arctic marine environment (Armitage et al. 2006, Wania 2007). HOWDOCHEMICALCONTAMINANTS REACHTHEARCTIC? Metals are naturally-occurring elements but Winds, ocean currents and rivers are all poten- are also generated through human activities. tial transport pathways for chemical contami- Elemental Hg (Hg0) is highly volatile, and nants to reach the Arctic (AMAP 2009). gaseous Hg0partitions readily into the atmos- Chemical characteristics, such as volatility and phere where it can undergo long-range atmos- water solubility, determine the potential of an pheric transport. Due to a complex set of organic chemical to become an Arctic contam- factors (Macdonald et al. 2005), polar regions inant (Wania 2003, 2006). Air is the most have become global sinks for Hg. important transport route to the Arctic for Relatively low levels of contaminants are volatile and semi-volatile contaminants includ- found in the terrestrial environment compared ing Hg (AMAP 2002). Many chlorinated with the marine environment, especially in the organics are present as gases even at low tem- high Arctic, due to snow cover in the winter peratures and are absorbed from the gas phase and subsequent transfer of deposited contami- by water, snow, soil and plant surfaces (Braune nants to freshwater systems during the rapid et al. 2005a). More recently, however, studies 135 –BRAUNE– spring snow melt (Semkin 1996). The Cana- 2007). Mercury is also readily transferred to dian Arctic terrestrial environment, for exam- the eggs (Wiener et al. 2003). Contaminant ple, has few significant contaminants issues burdens in the egg reflect residues assimilated that can be attributed to long-range transport over a long time period by the female and, par- and deposition of POPs and heavy metals, par- ticularly in migratory species, may integrate ticularly when compared with the freshwater exposure from a number of different locations and marine environments (Gamberg et al. (Hebert 1998, Monteiro et al. 1999). 2005). The major contaminant concerns for terrestrial animals are from non-essential ele- Contaminant concentrations can vary consid- ments such as cadmium (Cd) and Hg (Gam- erably among species depending on their feed- berg et al. 2005). ing and migration strategies (Braune et al. 2002, Buckman et al. 2004). For example, in Greenland, Peregrine Falcons (Falco peregri- CONTAMINANTSANDWILDLIFE nus) had higher levels of DDE, PCBs and Persistent chlorinated and brominated organo- other organochlorine contaminants in their contaminants, as well as Hg, bioaccumulate in plasma compared with Gyrfalcons (Jarman et wildlife (Braune et al. 2005a). For example, al. 1994). The authors attributed the difference concentrations of PCBs and Hg increase with in contaminant levels to the fact that Pere- age in Gyrfalcons (Falco rusticolus) (Ólafsdót- grines, which themselves are migratory, con- tir et al. 1995, Dietz et al. 2006). These com- sumed contaminated, migratory prey, both on pounds also biomagnify up the food chain their wintering and breeding grounds, whereas (Braune et al. 2005a) making those species the non-migratory Gyrfalcons consumed low feeding at high trophic positions more vulner- trophic-level, non-migratory prey (e.g. ptarmi- able to contaminant exposure via their diet gan, hare). Interpretation of contaminant con- (Hop et al. 2002, Borgå et al. 2004, Vorkamp centrations in biota may also be confounded if et al. 2004, Wolkers et al. 2004). Food web populations vary their diet over trophic levels studies in marine ecosystems suggest that through time (e.g. see Hebert et al. 1997, PFCs can also biomagnify but there have been 2000). few studies to date, and there have been no Spatial Patterns.—Compared with other cir- studies carried out for terrestrial or freshwater cumpolar countries, concentrations of many food webs (Butt et al. 2010). organochlorine contaminants in Canadian Arc- Seabirds feed at relatively high trophic posi- tic biota are generally lower than in the Euro- tions in Arctic marine food webs (Hobson et al. pean Arctic and eastern Greenland but are 2002, Hop et al. 2002) and, therefore, seabirds, higher than in Alaska, whereas Hg concentra- and in particular their eggs, have been used to tions are substantially higher in Canada and monitor contamination of the marine environ- western Greenland than elsewhere (Braune et ment in the Canadian Arctic since 1975 al. 2005a). Spatial patterns of PBDEs in (Braune 2007). At the time of egg formation, seabirds and marine mammals are similar to the lipophilic halogenated compounds are those seen for PCBs, with the highest concen- transferred along with fat to the eggs thus trations found in organisms from East Green- reflecting the contaminant burden in the land and Svalbard in the European Arctic, female at the time of laying (Verreault et al. lower concentrations in the Canadian Arctic 2006). Unlike other halogenated organic con- (except Hudson Bay), and the lowest concen- taminants (e.g., PCBs, PBDEs), PFCs appear trations in Alaska (de Wit et al. 2010). For to bind to proteins rather than partition into example, PBDE concentrations in eggs of lipid (Butt et al. 2010) but are found in eggs, alcids and/or Northern Fulmars (Fulmarus as well (Houde et al. 2006, Verreault et al. glacialis) are generally lower in the Bering 136 –CHEMICALCONTAMINANTSINARCTICWILDLIFE– Sea, intermediate in Canada, western Green- Cd levels among regions but the median con- land, Bjørnøya in the Barents Sea, northern centration for Canada was much higher than in Norway and the Faroe Islands, and highest on other countries, likely due to natural Cd expo- Iceland, east Greenland and Svalbard in the sure, possibly through a high intake of willow European high Arctic (de Wit et al. 2010). A (Salix sp.) which is known to contain higher similar pattern is seen for gulls (de Wit et al. amounts of Cd than other food plants (Peder- 2010). sen et al. 2006). In the marine environment, the highest Cd levels in seabirds were observed in Little is known about the BFR contamination northeastern Siberia and the lowest, in the Bar- of the terrestrial ecosystem in the Arctic; how- ents Sea, with intermediate levels in Arctic ever, concentrations of terrestrial animals at Canada and Greenland (Savinov et al. 2003). lower trophic levels were found to be low (de For Hg, concentrations in seabirds from the Wit et al. 2006, 2010), whereas they were Barents Sea were also lower than in Green- much higher in terrestrial birds of prey, partic- land, Canada, and northeast Siberia (Savinov ularly in Peregrine Falcons (de Wit et al. et al. 2003). Although there are some spatial 2006). For example, high BFR concentrations differences in Hg in the freshwater and terres- have been found in eggs of predatory birds trial environments, most levels are low feeding on terrestrial mammals and birds, par- (AMAP 2002). It should be noted that spatial ticularly Peregrine Falcons in northern Sweden differences in contaminant levels may also be (Lindberg et al. 2004) and Norway (Herzke et affected by differences in available food items. al. 2001), and more recently at several sites in South Greenland (Vorkamp et al. 2005). Temporal Trends.—The majority of legacy POPs (e.g., PCBs, DDT) have significantly Although the marine ecosystem has been well- declined in Arctic biota over the last several studied, there is a general lack of information decades (Rigét et al. 2010) whereas Hg has at the present time to define any circumpolar increased in a number of Arctic species (Rigét trends for PFCs (Butt et al. 2010). There are et al. 2011). The declines in the legacy POPs few reports of PFCs in terrestrial wildlife but are a consequence of past national and regional PFC levels have been measured in Common bans and restrictions on uses and emissions in Loons (Gavia immer), Mink (Mustela vison), circumpolar and neighbouring countries which Arctic Fox (Alopex lagopus) and Caribou began in the 1970s for chlorinated pesticides (Rangifer tarandus) from the Canadian Arctic and PCBs (Muir and de Wit 2010). Seabird (Martin et al. 2004, Tittlemier et al. 2005). In eggs from the Canadian high Arctic reflect the general, PFOS and perfluorooctane sulfon- documented decline in legacy POPs (Braune amide (PFOSA), as well as some of the 2007, Braune et al. 2007) as do eggs of PFCAs, were commonly detected (Butt et al. Alaskan Peregrine Falcons (Ambrose et al. 2010). 2000). However, concentrations of Hg have been increasing in seabird eggs from the Cana- Large-scale spatial patterns of element concen- dian high Arctic (Braune 2007, Braune et al. trations in tissues of terrestrial and freshwater 2006). In fact, Braune et al. (2006) found that animals may reflect both geochemical environ- Hg levels in eggs of the Ivory Gull (Pagophila ments as well as anthropogenic inputs, as is the eburnea) from the Canadian high Arctic, a case for Cd in Canadian Caribou, for example, species recently listed as “endangered” in which have higher Cd concentrations in some Canada (COSEWIC 2010), were among the Yukon herds where Cd is naturally higher in highest ever reported for seabird eggs from the the soils (Braune et al. 1999). A circumpolar Arctic marine environment. The pattern of survey of Cd in Willow Ptarmigan (Lagopus increasing Hg concentrations in Canadian Arc- lagopus) also showed considerable variation in tic seabirds in recent decades supports the 137 –BRAUNE– west-to-east circumpolar gradient in the occur- 2003), and the declining ΣPBDE concentra- rence of recently increasing Hg trends tions observed in the seabird eggs after 2003 reflected in Arctic biota. A recent analysis of may reflect the phasing out of Penta-BDE Hg time series for Arctic biota showed that product usage in North America after 2005 (de there is a higher proportion of temporal trend Wit et al. 2010). datasets, particularly for marine biota, in the Canadian and Greenland region of the Arctic As with the BFRs, there are inconsistencies in showing significant Hg increases than in the the PFC temporal trends, most of which are North Atlantic Arctic (Rigét et al. 2011). The from the North American Arctic and Green- reasons for this are complex but likely involve land. Martin et al. (2004) screened livers of anthropogenic and natural emissions coupled Northern Fulmars and Black Guillemots (Cep- with environmental and biological (e.g. food- phus grylle) collected from the Canadian high web) processes which may also be affected by Arctic in 1993 for the presence of PFCs and climate change. In contrast, Hg in terrestrial found relatively low concentrations of both biota and freshwater biota, for the most part, PFOS and the PFCAs in both species. Subse- showed either no change over time or a quent retrospective analyses showed that over- decreasing trend (Rigét et al. 2011). Likewise, all PFC concentrations in livers of Thick-billed Cd levels in biota and in the abiotic environ- Murres and Northern Fulmars had increased ment are, for the most part, either stable or significantly from 1975 to 2003–2004 (Butt et declining (Braune et al. 2005b). al. 2007). A recent review by Butt et al. (2010) generally showed increasing trends from the Temporal trend studies for BFRs in Arctic 1970s in Arctic wildlife, although some studies wildlife have generated differing results with from the Canadian Arctic showed recent some PBDEs showing increasing concentra- declines in PFOS levels. Temporal trends of tions and others showing a tendency to level PFCs in eggs of Swedish Peregrine Falcons off or decline in response to reductions in use also showed increasing concentrations of and emissions (de Wit et al. 2010). However, PFCAs whereas concentrations of PFOS lev- no uniform pattern in temporal trends emerges elled off after the mid-1980s (Holmström et al. for the Arctic. Concentrations of PBDEs 2010). In contrast, Ringed Seals (Phoca hisp- increased from 1986 to 2003 in Peregrine Fal- ida) and Polar Bears (Ursus maritimus) from con eggs from South Greenland (Vorkamp et Greenland continue to show increasing PFOS al. 2005). In the Canadian Arctic, PBDEs were concentrations. The inconsistency in the PFC first detected in seabird liver and eggs by temporal trends between regions may represent Braune and Simon (2004). Subsequent retro- differences in emissions from source regions spective analyses and continued monitoring (Butt et al. 2010). showed that concentrations of total PBDE (ΣPBDE) concentrations in eggs of Thick- Effects.—Given the complex and dynamic billed Murres (Uria lomvia) and Northern Ful- environment in which animals live, it is diffi- mars from the Canadian high Arctic steadily cult to establish a cause-effect relationship for increased between 1975 and 2003 after which any one stressor. A recent assessment on the time, levels appear to have started to decline effects of POPs on Arctic wildlife and fish con- (Braune 2008). An increase in ΣPBDE concen- cluded that there still remains minimal evi- trations between 1976 and 2004 is also dence that POPs are having widespread effects reflected in eggs of the Ivory Gull in the Cana- on the health of Arctic organisms, with the dian high Arctic (Braune et al. 2007). North possible exception of Polar Bears in East America accounted for most of the global Greenland and Svalbard, as well as Svalbard demand for the commercial Penta-BDE prod- Glaucous Gulls (Larus hyperboreus) where uct used in polyurethane foam (Hale et al. 138 –CHEMICALCONTAMINANTSINARCTICWILDLIFE– studies have demonstrated sub-lethal physio- including PFCs in chicks of three raptor logical effects (Letcher et al. 2010). species in northern Norway which suggested potential effects on liver, kidney, bone, Effect studies on wild terrestrial birds in the endocrinology and metabolism (Sonne et al. Arctic have been limited to Peregrine Falcons, 2010). although laboratory studies have been carried out using the American Kestrel (Falco Many high trophic level predators associated sparverius). Population declines of Peregrine with marine and other aquatic ecosystems are Falcons at a number of North American loca- exposed to Hg primarily as methylmercury tions during the mid-part of the last century (MeHg) in their diet, and in some areas of the were associated with DDE-induced eggshell Arctic, Hg concentrations in marine food webs thinning (Peakall et al. 1990). With the signif- have significantly increased in recent decades icant decrease in most of the legacy POPs (Rigét et al. 2011) suggesting that levels in including p,p’-DDE, there has been an increase some marine mammals, birds, and fish may in eggshell thickness in Alaskan Peregrines reach the point where adverse biological and no apparent exceedance of toxicity thresh- effects might be expected (AMAP 2002). olds for the legacy POPs for eggs sampled However, compared to the amount of contam- between 1988 to 1995 (Ambrose et al. 2000). inant data available for the Arctic region, Peregrine Falcon eggs sampled from South knowledge of the effects of these contaminant Greenland between 1986 and 2003 also loads are very limited and, therefore, most showed a decreasing trend for the legacy POPs evaluations of potential toxic effects of con- (Vorkamp et al. 2009), and Falk et al. (2006) taminants in wildlife are based on comparisons demonstrated a significant long-term decrease of tissue residue levels with toxicity thresholds in eggshell thinning in Greenlandic Peregrines. derived from laboratory-based studies reported However, Johnstone et al. (1996) found no in the literature. Exceedance of these toxicity improvement in eggshell thickness in eggs thresholds, however, does not necessarily sampled in the Canadian tundra during 1982– result in adverse biological effects or popula- 1986 and 1991–1994, although p,p’-DDE tion-level impacts. For example, Hg levels in residue levels did decline. A recent study on 30% of the eggs of Peregrine Falcons sampled Peregrines from Sweden showed that the aver- between 1991 and 1995 in Alaska exceeded age brood size decreased with increasing the critical threshold for reproductive effects ΣPBDE concentrations, suggesting that (Ambrose et al. 2000) although no causal asso- PBDEs could influence reproduction in this ciation with Hg was established. Likewise, Cd species (Johansson et al. 2009). However, in some ptarmigan, Caribou and Moose (Alces Nordlöf et al. (2010) found no correlation alces) in the Yukon Territory, which has high between levels of BFRs and reproductive suc- levels of naturally-occurring Cd, are high cess in White-tailed Eagles (Haliaeetus albi- enough to raise concern for kidney damage, cilla) in four regions of Sweden. Letcher et al. but effects have not been documented (AMAP (2010) concluded that there is currently a low 2002). Since Hg concentrations are still risk from ΣPBDE and HBCD exposure in the increasing in some Arctic animals (Rigét et al. eggs of Arctic birds with respect to the repro- 2011), Arctic species (particularly top preda- ductive and developmental effects reported for tors) are likely to be exposed to increasing con- captive Kestrels by Fernie et al. (2009). The centrations of Hg for some time to come. effects of PFCs on wildlife are not well known, in particular for Arctic biota (Butt et al. 2010). EFFECTSOFCLIMATECHANGE However, a recent study showed a relationship between blood plasma clinical-chemical Many of the transfer, transformation and stor- parameters and organohalogen compounds age processes driving global contaminant 139 –BRAUNE– cycles are likely to be significantly affected by LITERATURECITED the impacts of climate change, especially as AMAP. 2002. Arctic Pollution 2002. 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