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. 2020 Sep 16;11(1):4650.
doi: 10.1038/s41467-020-18398-5.

Potential impacts of mercury released from thawing permafrost

Kevin Schaefer  1 , Yasin Elshorbany  2 , Elchin Jafarov  3 , Paul F Schuster  4 , Robert G Striegl  4 , Kimberly P Wickland  4 , Elsie M Sunderland  5
Affiliations

Potential impacts of mercury released from thawing permafrost

Kevin Schaefer et al. Nat Commun. .

Abstract

Mercury (Hg) is a naturally occurring element that bonds with organic matter and, when converted to methylmercury, is a potent neurotoxicant. Here we estimate potential future releases of Hg from thawing permafrost for low and high greenhouse gas emissions scenarios using a mechanistic model. By 2200, the high emissions scenario shows annual permafrost Hg emissions to the atmosphere comparable to current global anthropogenic emissions. By 2100, simulated Hg concentrations in the Yukon River increase by 14% for the low emissions scenario, but double for the high emissions scenario. Fish Hg concentrations do not exceed United States Environmental Protection Agency guidelines for the low emissions scenario by 2300, but for the high emissions scenario, fish in the Yukon River exceed EPA guidelines by 2050. Our results indicate minimal impacts to Hg concentrations in water and fish for the low emissions scenario and high impacts for the high emissions scenario.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. A schematic of our terrestrial mercury (Hg) model.
The soil extends down to 15 meters with an active layer that thaws in summer and refreezes in winter. The organic carbon and Hg extend down to three meters. Hg deposits onto the surface from the atmosphere and bonds to plant and soil organic matter. As organic matter decays, elemental mercury (Hg0) is released into the atmosphere, some mercury cation (HgII) is exported into rivers, and the remaining HgII is recycled back into the organic matter. We use empirical relationships to estimate methyl mercury (MeHg) concentrations in water from HgII export and total Hg concentrations in fish from MeHg concentrations.
Fig. 2
Fig. 2. Annual net elemental mercury (Hg0) flux into the atmosphere.
The net flux is Hg0 evasion into the atmosphere minus Hg0 deposition from the atmosphere, summed across all permafrost regions. The shaded areas represent uncertainty in the net Hg0 flux and the dashed line represents current global anthropogenic emissions.
Fig. 3
Fig. 3. Cumulative mercury (Hg) loss per area by 2300.
Total Hg loss is net elemental mercury (Hg0) flux to the atmosphere plus mercury cation (HgII) export by rivers summed from 1901 to 2300. The red outline indicates the spatial extent of the Yukon River Basin.
Fig. 4
Fig. 4. Mercury cation (HgII) export for the Yukon River Basin (YRB).
The annual riverine HgII export is the sum of HgII export across the YRB outlined in Fig. 3. The shaded areas represent uncertainty and the black dots indicate observed riverine export.
Fig. 5
Fig. 5. Mercury cation (HgII) concentrations in the Yukon River.
We calculated daily HgII concentrations at Pilot Station, Alaska on the Yukon River. The shaded areas represent uncertainties and the dashed line represents the former EPA ambient water quality criterion of 12 ng Hg L−1.
Fig. 6
Fig. 6. Mercury (Hg) concentration in fish in the Yukon River.
The shaded areas represent uncertainty in the simulated values and the dashed line represents the EPA criterion. The dot and vertical error bar shows the median and range of observed concentrations in fish,.
See this image and copyright information in PMC

References

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