Mercury dynamics in Arctic fjord marine food webs

Marine chemical pollution poses known threats to human health and to biodiversity, ecosystem and societal services. The Arctic region is a major sink of global mercury (Hg) pollution. Arctic sediments, sea and glacial ice constitute vast Hg reservoirs. Recent studies raise concerns about their increasing role as local Hg sources. In a rapidly warming Arctic, the consequences of potentially increased environmental Hg on marine biota remain unknown. The objective of HgFJORD is to identify the pathways of Hg bioaccumulation in marine food webs of the High Arctic Kongsfjorden (Svalbard). This changing glacial fjord is recognized as a ‘natural laboratory’ of climate change in the Arctic. Earlier research has shown the sole measurement of Hg levels as insufficient to connect biotic Hg dynamics to environmental change, whereas the analysis of Hg stable isotopes proved to be a promising tool for source discrimination and biotic transfer. HgFJORD will build on the novel application of stable isotope analysis to identify the sources of Hg within the fjord system and the pathways to Hg accumulation. Two sampling campaigns are planned in June and August 2024. The collaboration between the Norwegian Polar Institute and the University of Liege during these two fieldworks will allow the analysis of Hg stable isotope analysis in unique biotic and abiotic samples including marine and glacial sediments, phyto- to macrozooplantlon, birds and seals, and assess the effect of spring blooming (June) and glaciers melting run-off (August) on Hg local sourcing. The empirical output of HgFJORD will be used to develop an adaptive risk assessment and applied management model for the forecasting of the impact of climate change on the dynamics of pollutants in Arctic coastal systems. This will be the main objective of a future project starting September 2024 (From the SEA to the SOLution. An integrative tool to assess marine pollution in a changing Arctic (SEASOL); RiS: 12272).