From Sources to Seabirds - Tracking Organic Pollutants from European Air to Arctic Seabirds over time and space

Persistent organic pollutants (POPs) are of global concern due to their harmful properties and long-range environmental transport (LRET). Despite regulations, POPs continue to be detected in remote regions. Moreover, replacement chemicals are increasingly detected in the environment, raising concern about their environmental fate and impact on the environment. Here, the occurrence of regulated, newly regulated, and unregulated organic contaminants in European air, and trends of regulated POPs in an Arctic seabird are assessed. Future exposure of a regulated POPs in Arctic seabirds is also examined. Air samples from European background sites in 2016 were analysed for new contaminants such as Dechlorane Plus (DP) and Dechlorane-602 (Dec-602), both of which were unregulated, and old/regulated POPs (e.g., dichlorodiphenyltrichloroethane (DDT) and and hexachlorobenzene (HCB)). DP was widely detected, with decreasing concentrations with increasing latitude, supporting its LRET potential. Dec-602 was also detected, marking one of the few studies to confirm its presence in background air. The spatial trends of DP and Dec-602 mirrored those of the old POPs. Declining concentrations were seen for most POPs when comparing our study (2016) to a similar study (2006). The exemption from this was HCB, a regulated POPs that had increasing concentrations over the decade, and higher concentrations at higher latitudes. Blood samples from female common eiders (Somateria mollissima) from Svalbard (2007-2017) was analysed, and revealed increasing trends for several old POPs, including HCB and DDT-metabolites. Statistical modelling linked higher contaminant concentrations to lower body mass and clutch size. Furthermore, warmer ambient temperatures were associated with increased concentrations of key POPs, pointing to climate-related influences on contaminant exposure. To predict future exposure, the Nested Exposure Model (NEM) was further developed and evaluated for three Arctic seabird species: common eider, black-legged kittiwake (Rissa tridactyla), and glaucous gull (Larus hyperboreus). The model successfully predicted polychlorinated biphenyl (PCB)-153 concentrations across species, sexes, and sample years. Under a scenario of declining global emissions, PCB-153 exposure in seabirds was predicted to decrease by 99% by 2100. Simulations accounting for dietary shifts and altered lipid metabolism due to climate change showed small additional effects. Together, these findings provide new insights into contaminant exposure in Arctic ecosystems. Continued monitoring of regulated and unregulated chemicals, and utilizing modelling as a tool to better understand the exposure of contaminants, are essential to guide regulation and protect Arctic wildlife from harmful chemicals in a changing climate.