Remobilization of Mercury from Degrading Permafrost Peatlands

Mercury (Hg) is a toxic trace metal that has been sequestered in Northern permafrost soils for thousands of years. Today, these systems are estimated to store as much Hg as all other soils, the atmosphere and the oceans combined.

If some of this Hg is released into Hg’s modern biogeochemical cycle, it could worsen Hg pollution and counteract global efforts to protect human and wildlife health from Hg exposure. Climate-driven release of Hg upon permafrost thaw has already been demonstrated. A robust understanding of the underlying soil Hg remobilization processes is, however, still missing.

This program aims to unravel the climate vulnerability of Arctic Hg stocks by investigating the reduction and desorption processes of Hg along permafrost thaw gradients. We will do this by applying both field- and laboratory-based approaches.

The field study will be conducted in Tavvavuoma (one of the most extensive permafrost peatland areas in Fennoscandia) along permafrost thaw transects where we already have demonstrated decreasing concentrations of Hg in the soil matrix upon permafrost thaw and peat inundation.

In the laboratory, we will then apply novel experimental approaches where reduction and desorption processes and potential are uncovered.

Together, these approaches will allow us to generate a deeper understanding of permafrost soil Hg remobilization processes and link these to land destabilization processes, carbon remineralization, and other key biogeochemical processes.