Bio-essential and toxic elements transformation and transport in the Arctic under pressure of Siberian Continental Shelf permafrost thawing

BEST-Siberian aims to provide data and knowledge on the environmental and ecological risks due to increasing mobility and transformation of bio-essential and toxic trace elements, such as iron and mercury, on the Siberian continental shelf under permafrost thawing. During the 1st year of the project, there were collected samples of carbon, iron, mercury, and trace metals near the river mouths of Ob, Yenisey, Pyasina, and in the open Kara sea (the 86th cruise of the research vessel Akademik Mstislav Keldysh in October - November 2021). Besides this, there were collected samples from the rivers. The collected samples were delivered to NTNU, and during the 2d and 3d years of the project they were analyzed. Totally there were analyzed 60 sediments samples, 30 sea water samples and 19 river water samples for mercury, iron and carbon. During the work on modeling, there were analyzed consequences of the permafrost thawing origin methane seeping on the ocean acidification and elaborated a model of the Arctic biogeochemistry seasonal changes, which will be used for the mercury modeling. There were published 6 papers and 1 MSc thesis. The project results were reported at 4 conferences.

Climate change-induced thawing of Arctic permafrost may have cascade impacts on many important marine biogeochemical processes, including the absorption and release of greenhouse gases. BEST-Siberian aims to provide data and knowledge on the environmental and ecological risks due to increasing mobility and transformation of bio-essential and toxic trace elements, such as iron and mercury, on the Siberian continental shelf under permafrost thawing. The Siberian continental shelf is part of the Arctic Ocean and is the largest continental shelf on Earth. Due to climate change, permafrost thawing is already creating environmental and ecological risks here. Changes in this vast region could have strong impacts on the Arctic Ocean and beyond, but to date little is known about the likely extent of such impacts and the necessary process resolution remains lacking in Earth System Models. BEST-Siberian will: i) assess the impacts of terrestrial and subsea permafrost thawing on the Siberian continental shelf; ii) develop parameterizations suitable for incorporation into the next generation of Earth System models; iii) Make the knowledge ready to be used for management tools and policy/decision support systems, suggesting environmental targets and indicators coupled to recommendations for their monitoring. Understanding permafrost-driven fluxes and transformations is of fundamental importance for developing realistic scenarios of environmental change and for the sustainable management of regional seas and the global ocean. BEST-Siberian findings will contribute to the implementation of the MSFD and EU frameworks on the Arctic and adjacent coastal systems and will improve predictive climate modeling approaches for the Arctic Ocean, its biogeochemistry, ecology, and socio-economical adaptation to the impacts of climate change and mitigation measures.