Permafrost Thaw Increases Methylmercury Formation in Subarctic Fennoscandia

[Image: see text] Methylmercury (MeHg) forms in anoxic environments and can bioaccumulate and biomagnify in aquatic food webs to concentrations of concern for human and wildlife health. Mercury (Hg) pollution in the Arctic environment may worsen as these areas warm and Hg, currently locked in permaf...

Full description

Bibliographic Details
Published in:Environmental Science & Technology
Main Authors: Tarbier, Brittany, Hugelius, Gustaf, Kristina Sannel, Anna Britta, Baptista-Salazar, Carluvy, Jonsson, Sofi
Format: Text
Language:English
Published: American Chemical Society 2021
Subjects:
Arctic
Fennoscandia
Fennoscandian
Peat
Peat plateau
permafrost
Subarctic
Thermokarst
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8277125/
http://www.ncbi.nlm.nih.gov/pubmed/33902281
https://doi.org/10.1021/acs.est.0c04108
Description
Summary:[Image: see text] Methylmercury (MeHg) forms in anoxic environments and can bioaccumulate and biomagnify in aquatic food webs to concentrations of concern for human and wildlife health. Mercury (Hg) pollution in the Arctic environment may worsen as these areas warm and Hg, currently locked in permafrost soils, is remobilized. One of the main concerns is the development of Hg methylation hotspots in the terrestrial environment due to thermokarst formation. The extent to which net methylation of Hg is enhanced upon thaw is, however, largely unknown. Here, we have studied the formation of Hg methylation hotspots using existing thaw gradients at five Fennoscandian permafrost peatland sites. Total Hg (HgT) and MeHg concentrations were analyzed in 178 soil samples from 14 peat cores. We observed 10 times higher concentrations of MeHg and 13 times higher %MeHg in the collapse fen (representing thawed conditions) as compared to the peat plateau (representing frozen conditions). This suggests significantly greater net methylation of Hg when thermokarst wetlands are formed. In addition, we report HgT to soil organic carbon ratios representative of Fennoscandian permafrost peatlands (median and interquartile range of 0.09 ± 0.07 μg HgT g(–1) C) that are of value for future estimates of circumpolar HgT stocks.

Similar Items