Abstract
Considerable amounts of previously deposited persistent organic pollutants (POPs) are stored in the Arctic cryosphere. Transport of freshwater and terrestrial material to the Arctic Ocean is increasing due to ongoing climate change and the impact this has on POPs in marine receiving systems is unknown This study has investigated how secondary sources of POPs from land influence the occurrence and fate of POPs in an Arctic coastal marine system. Passive sampling of water and sampling of riverine suspended particulate matter (SPM) and marine sediments for analysis of polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) was carried out in rivers and their receiving fjords in Isfjorden system in Svalbard. Riverine SPM had low contaminant concentrations (<level of detection-28pg/g dw ΣPCB14, 16-100pg/g dw HCB) compared to outer marine sediments 630-880pg/g dw ΣPCB14, 530-770pg/g dw HCB). There was a strong spatial gradient in sediment PCB and HCB concentrations with lowest concentrations in river estuaries and in front of marine-terminating glaciers and increasing concentrations toward the outer fjord. This suggests that rather than leading to increased concentrations, inputs of SPM from land lead to a dilution of contaminant concentrations in nearshore sediments. Preliminary estimates of SPM:water activity ratios suggest that terrestrial particles (with low contaminant concentrations) may have the potential to act as sorbents of dissolved contaminants in the coastal water column, with implications for bioavailability of POPs to the marine food web. There is concern that ongoing increases in fluxes of freshwater, sediments and associated terrestrial material (including contaminants) from land to the Arctic Ocean will lead to increased mobilization and transport of POPs to coastal ecosystems. However, the results of this study indicate that on Svalbard, inputs from land may in fact have the opposite effect, leading to reduced concentrations in coastal sediments and waters.
Highlights
Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB), are highly resistant towards degradation and can undergo long-range transport (LRT) to remote areas, where they bioaccumulate and biomagnify and can potentially cause adverse effects (AMAP, 2004; Riget et al, 2019)
Our results suggest that input of terrestrial/riverine sediments with low contaminant concentrations is the dominant factor governing the spatial distribution of PCBs and HCB within Isfjorden
This study has shown that inputs from land play an important role in governing concentrations of PCB and HCB in the receiving marine environment, but not in the way we had expected
Summary
Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB), are highly resistant towards degradation and can undergo long-range transport (LRT) to remote areas, where they bioaccumulate and biomagnify and can potentially cause adverse effects (AMAP, 2004; Riget et al, 2019). The occurrence of PCBs and HCB in remote as well as more populated areas on Svalbard is well-documented through several studies and monitoring programmes and their environmental behaviour is fairly well-known, which make them well-suited for studies on the impact of environmental processes on contaminant cycling These persistent and bioaccumulative compounds are known to pose a risk for long-lived Arctic top predators, where concentrations are often above thresholds for potential toxic effects (Carlsson et al, 2018; Hung et al, 2016; Jartun et al, 2009; Pedersen et al, 2011). Transport and fluxes of organic contaminants from meltwater to the receiving marine environment and their fate in coastal waters have gained less attention (Ma et al, 2015; Pouch et al, 2017, 2018; Sapota et al, 2009)
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