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Impact of global change on the remobilization and Bioaccumulation of organic Pollutants in PolAr aquatic food webs

Final Report Summary - BIOPOLLAR (Impact of global change on the remobilization and Bioaccumulation of organic Pollutants in PolAr aquatic food webs)

This Marie Curie research project aimed to study the effect of climate warming and permafrost melting on organic pollutants in food webs from freshwater and marine Arctic ecosystems and maritime Antarctica using long temporal series of legacy persistent organic pollutants (POPs) such as polychlorinated biphenyl’s (PCBs), organochlorine pesticides (OCPs) such as (DDTs, HCB, HCHs), brominated flame retardands (BDEs) and recently regulated pollutants such as perfluoro alkyl substances (PFASs). For achieving these goals, a combination of laboratory analysis in achieved samples, intensive sampling campaigns in the High Arctic and in the maritime Antarctica, and statistical tools were applied on collected and archived samples. More than 1000 samples, (from different environmental compartments), including archived samples have been considered during the whole duration of the project. The proposal has addressed a knowledge gap on the influence of climate change on the availability of contaminants in Arctic ecosystems and food webs and the presence for the first time of emerging pollutants such as organophosphate retardants (OPEs) in Antarctic biota (e.g plankton) and seawater.
Over the long-term series studied (1989−2016) of POPs in ringed seals and Arctic char in 4 High Arctic Lakes, statistical analysis has shown that annual air temperatures exhibited increasing trends on Cornwallis Island, which has resulted in increasing summer glacier surface temperatures in the Canadian High Arctic Island over the period 2005-2012. Increasing temperatures in the Arctic have led to changes in snow and ice cover on Arctic freshwater and terrestrial ecosystems, together with a reduction of snow precipitation, sea-ice retreat, alterations of the lake productivity during the warmer periods and rate of mass loss from glaciers nearly tripled between 2004–06 and 2007–09. Temporal trends and climate related parameters affecting the fate of legacy POPs such as PCBs and organochlorine pesticides were examined in landlocked Arctic char from four lakes in the Canadian Arctic. Among biological parameters, lipid content was a key factor explaining the concentration of most POPs in Arctic char. Legacy PCBs and chlorinated pesticides generally showed declining trends of concentrations in Arctic char, consistent with past restriction on uses and emissions of POPs. However, increases in lake primary productivity (measured as chlorophyll a) exerted a dilution effect on POPs concentrations in Arctic char. Concentration of POPs in char from the last two decades were positively correlated with interannual variations of the North Atlantic Oscillation (NAO). Higher concentrations of POPs in Arctic char were observed in 3 of the 4 lakes during positive NAO phases. This, together with increasing local Arctic temperatures, could lead to increases on POPs concentrations in char from remote Arctic Lakes in future decades. Also, if there are nearby secondary sources as may be the case for Resolute Lake, located near an airport where increasing levels were found for HCB and toxaphene, probably due to the mobilization from secondary sources in soils. The analysis of temporal trends of POPs in Ringed seal, the most abundant Arctic pinniped with a circumpolar distribution also showed a declining trend of legacy POPs with the relative magnitude of ΣDDT (-3.1 to -7.1 %/yr) > α-HCH (-3.9 to 8.6 %/yr) > Σ10PCB (-1.9 to -5.6 %/yr). Declines were most rapid in Hudson Bay animals and least in the Beaufort Sea samples. This declining trend contrast with increases concentrations of brominated flame retardants such as α-HBCDD and BTBPE in Beaufort and Lancaster, which suggest their continuous inputs in the Canadian Arctic environment and warrant further surveillance and research on the effects of these substances in northern wildlife. Both, arctic char and seals, are at the top of the freshwater and marine food webs respectively and are important sources of food for Inuit communities.
Results from an intensive field campaign in two paired watersheds and lakes at the Cape Bounty Arctic Watershed Observatory (CBAWO) located on Melville Island (74°55' N, 109°35' W) have revealed that legacy POPs and OCPs in Arctic char declined in East Lake over the period 2008 to 2016 but have significantly increased (especially more hydrophobic chemicals such as PCBs and DDTs) in West Lake. Increases of PCBs were also observed in midges sampled in the stomach content of the char (2008-2016) from West Lake in comparison with the those midges found in stomach content from char in East Lake. This together with increases on sediment rates on West Lake since 2010 combined with high turbidity, elevated particulate organic carbon (POC) and dissolve organic carbon (DOC), observed in West Lake, probably associated with continued permafrost disturbances and subaqueous slumps in the West Lake watershed are altering the temporal trends of legacy POPs, in Arctic char from West Lake. The results for legacy POPs shown, are gradually bringing to light the influence of permafrost degradation and sediment slumping on temporal trends of POPs in Arctic char. The greater inputs of terrestrial carbon and higher turbidity occurred in West Lake especially after 2012 are mobilizing old sources of PCBs attached to organic carbon, which are affecting the concentrations of PCBs and DDTs in the lower trophic levels (e.g midges) and therefore exerting an important impact on temporal trends of PCBs and DDTs in Arctic char from West Lake. On the other hand, no significant disturbances are observed in East Lake, in which the declining trends of all pollutants have been observed. For those less hydrophobic compounds such as HCHs, HCB and PFASs no significant differences in concentration on temporal trends in char were observed, likely due to the low sorption of these pollutants to the organic carbon. The analysis of pollutants in terrestrial compartments such as vegetation and soils collected in the catchments areas of West and East lakes show that both soils and vegetation act as important repositories of hydrophobic PCBs and OCPs. Any alteration on Arctic soils or vegetation due to warming or other perturbations will likely provide large inputs of stored pollutants to the atmosphere and to adjacent rivers, lakes, potentially affecting water quality and arctic food webs, including those organisms such as caribou and reindeer feeding on arctic vegetation. Antarctic food webs (plankton), together with seawater and snow samples collected at Livingston Island were analysed for brominated flame retardants (BDEs) and emerging pollutants such as OPES. Both groups of chemicals were detected in all the samples but higher concentrations of these POPs were detected in plankton samples collected close to the glacier in contrast to those samples collected further away from the glacier, suggesting that the influence of ice melting was also an important source of pollutants to the bottom base of the Antarctic food webs (e.g plankton). Furthermore, the applicant has participated in other two studies related to the air-land-ocean coupling of concentrations and fluxes of PAHs, PCBs and organochlorine pesticides.
The findings of this study funded through the Marie Curie Actions are very relevant for the international scientific community. Results will be very important for the Stockholm Convention, the Arctic Monitoring and Assessment Programme (AMAP) and the Scientific Committee on Antarctic Research (SCAR). Results obtained will be shared with the AMAP climate- contaminants impacts assessment and SCAR groups. The output of this project is also very relevant for local Inuit communities as freshwater environments such are lakes and rivers and marine environments are major ecosystem features of the circumpolar Arctic and provide important sources of food (e.g Arctic char, seals) as well as drinking water for Inuit communities. Alteration of organic carbon sources (soil, sediments, etc) due to accelerated warming as those observed in West Lake will make food of less quality and more contaminated especially with legacy PCBs and DDTs. The output of the project will be also shared with the Nunavut Environmental Contaminants Committee.