The study was led by the U.S. Geological Survey and includes Gustaf Hugelius, Bolin Centre/Department of Physical Geography. The team combined mercury concentrations from permafrost cores from Alaska with extensive legacy data to estimate how much mercury is locked in northern permafrost soils.

The new estimates suggest that soils of the northern permafrost region store more mercury than what has previously been describe in all other soils, the ocean and the atmosphere combined. The new study was published in Geophysical Research Letters (

- While it was known that Arctic ecosystems contain much mercury, says Gustaf Hugelius, but      we had not expected levels to be so high also in the deep and ancient permafrost. This new insight opens up many questions. Most urgently, what are the risks to ecosystems and human populations as permafrost thaws?

Measurements from permafrost peatlands in Northern Sweden are in line with the overall findings and show relatively high mercury levels. But it remains uncertain how the mercury may affect ecosystems or humans if it is released from thawing permafrost. Scientist do not yet know to which extent the permafrost mercury could be released as the more toxic form methylated mercury.  

Thawing permafrost peatland in Tavvavuoma, northern Sweden. Data shows high levels of mercury also in these peatlands. Photo: Gustaf Hugelius.