278 - Processes Affecting Mercury Transformation and Biotic Uptake in the Arctic

The environmental exposure of Hg is determined not just by the amount of Hg entering the Arctic, but also by biogeochemical and ecological processes occurring in the Arctic. These processes affect MeHg uptake in biota by regulating the bioavailability, methylation and demethylation, bioaccumulation and biomagnification of MeHg in Arctic ecosystems. Here, we will present a synthesis of work conducted for the AMAP Assessment 2021: Mercury in the Arctic on the processes affecting mercury transformation and biotic uptake in the Arctic. We focus on scientific progress made in the last decade on processes leading to environmental MeHg exposure by presenting (1) a new mass balance for MeHg in the Arctic, and new information on (2) our mechanistic understanding of Hg (de)methylation processes, (3) where hotspots of MeHg are found in the Arctic and, finally, (4) processes affecting Hg accumulating in Arctic biota. Key findings include the role of thermokarst wetlands, ponds and lakes as Hg methylation hotspots as well as the shallow subsurface MeHg maxima observed in the Arctic Ocean.

Authors: Sofi Jonsson, Michelle Nerentorp Mastromonaco, Feiyue Wang,Andrea G. Bravo, John Chételat, Thomas Douglas, Gretchen Lescord, Liisa Ukonmaanaho, Lars-Eric Heimbuerger-Boavida, Warren RL Cairns