Researchers have discovered the world's largest amount of toxic mercury trapped inside the frozen ground in permafrost regions.
Mercury is a global pollutant that is released into the air from a variety of sources, from power plants to volcanoes, and is washed into bodies of water by rainfall. Hg deposits onto the soil surface from the atmosphere, where it bonds with organic matter. In regions, where the soil is at or below 0°C for at least two consecutive years (permafrost), mercury storage in the soil surface layer is enhanced. Even worse, over thousands of years, sedimentation buried mercury bound to organic material and froze it into the permafrost.
Figure: Permafrost map: Darker shades of purple indicate higher
percentages of permanently frozen ground. Map courtesy Philippe
Rekacewicz, UNEP/GRID-Arendal; data from International Permafrost
Association, 1998. Circumpolar Active-Layer Permafrost System (CAPS),
The new study:
Researchers from the U.S. Geological Survey studied the stored mercury in core samples from the Alaskan permafrost. From the results they then calculated the average level of mercury throughout the world. Permafrost covers approximately 24 percent of the Northern Hemisphere, including large portions of Canada and Russia. The estimated mercury amount in permafrost soil is nearly twice as much present in all other soils, the ocean, and the atmosphere combined. The active surface layer alone represents the largest Hg reservoir on the planet. The original publication:
The authors argue that the Hg stored in permafrost soils represents an environmental risk as permafrost continues to thaw in the future due to climate change. Some portion of that will spread through water or air into the ecosystem and eventually into animals. If that’s not alarming enough, toxic mercury could also get into the atmosphere and travel around the world, affecting not just the northern hemisphere, but the whole planet.
Paul F. Schuster, Kevin M. Schaefer, George R. Aiken, Ronald C. Antweiler, John F. Dewild, Joshua D. Gryziec, Alessio Gusmeroli, Gustaf Hugelius, Elchin Jafarov, David P. Krabbenhoft, Lin Liu, Nicole Herman-Mercer, Cuicui Mu, David A. Roth, Tim Schaefer, Robert G. Strieg, Kimberly P. Wickland, and Tingjun Zhang, Permafrost Stores a Globally Significant Amount of Mercury,
Geophys. Res. Let., 45 (2018). doi: 10.1002/2017GL075571
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. Science of the Total Environment, 408/20 (2010) 4778–4783. doi: 10.1016/j.scitotenv.2010.06.056 Related EVISA Resources
Link Database: Toxicity of Organo-mercury compounds Link Database: Mercury exposure through the diet Link Database: Environmental cycling of methylmercury Link Database: Environmental cycling of inorganic mercury Link Database: Environmental pollution of methylmercury Link Database: Environmental pollution of inorganic mercury Link Database: Toxicity of mercury Related EVISA News
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last time modified: February 7, 2018