A danger is lurking under the permafrost in the Arctic.
Magdalene Isabel Smith, PhD student in Earth Sciences at the University of Southern California Dornsife, examines what lies beneath.
Magdalene Isabel Smith is a PhD student in Earth Sciences. She is interested in geochemistry and hydrology and is currently studying permafrost in Alaska, looking specifically at the transport of mercury to understand permafrost degradation and identify risks associated with climate change. She work is under the tutelage of Professor of Earth Sciences and Environmental studies, Josh West who teaches and leads a research group that includes diverse graduate and undergraduate students. His research is at the intersection of Earth’s landscapes, water & soil resources, and the carbon cycle & climate.
Toxic Mercury in Arctic Permafrost
As the Arctic warms 4 times faster than the global average, rapidly thawing permafrost could release significant amounts of mercury into rivers like the Yukon and the surrounding environment.
Natural atmospheric circulation pushes gaseous mercury toward high latitudes, where plants absorb mercury from the air and when they die and decompose, the mercury is stored in frozen soils called permafrost.
Mercury has accumulated in permafrost for millennia. However, climate change is accelerating permafrost thaw, which could release mercury-rich sediments into the rivers. How much mercury will be released, and its effects remain unknown.
Our research examined mercury levels in sediments from the Yukon River Basin. Previous measurements were limited, only sampling the top three meters of permafrost. Our team sampled from riverbanks, allowing us to access deeper layers to provide a more accurate picture of mercury content.
We find that fine-grained sediments contain more mercury than coarse-grained ones, suggesting that sediment properties may influence how much mercury is stored. Our research confirmed that mercury levels in riverbank sediments matched the higher estimates from earlier Arctic studies, validating that permafrost stores large amounts of mercury.
We also examined changes in the Yukon River’s path, which is crucial because how fast the river moves determines if mercury is being transported or stored. We find that a majority of the mercury is currently being stored, but this could change under warmer conditions.
While permafrost mercury isn’t an immediate threat, its release and sequential uptake by local aquatic food webs presents an increasing risk to the 5 million people living in the Arctic Circumpolar whose diets strongly depend on aquatic protein sources.
We hope the tools we’ve developed will enable a better assessment of the amount of mercury in Artic soils and whether it presents a growing problem for the environment and public health.
Read More:
[IPO Publishing] – Mercury stocks in discontinuous permafrost and their mobilization by river migration in the Yukon River Basin
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