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This content will become publicly available on April 29, 2017

Title: Warming increases methylmercury production in an Arctic soil

The rapid temperature rise in Arctic permafrost concerns not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) that may endanger humans, as well as wildlife in terrestrial, aquatic, and marine ecosystems. Decomposition of SOC provides an energy source for microbial methylation, although little is known how rapid permafrost thaw affects Hg methylation and how SOC degradation is coupled to MeHg biosynthesis. We describe rates of MeHg production in Arctic soils from an 8-month warming microcosm experiment under anoxic conditions. MeHg production increased >10 fold in both organic- and the mineral-rich soil layers at a warmer temperature (8 C) compared to a sub-zero temperature ( 2 C). MeHg production was positively correlated to methane and ferrous ion concentrations, suggesting that Hg methylation is coupled with methanogenesis and iron reduction. Labile SOC, such as reducing sugars and alcohol, were particularly effective in fueling the initial rapid biosynthesis of MeHg. In freshly amended Hg we found that there was more bioavailable than existing Hg in the mineral soil. Finally, the data indicate that climate warming and permafrost thaw could greatly enhance MeHg production, thereby impacting Arctic aquatic and marine ecosystemsmore » through biomagnification in the food web.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Univ. of Science and Technology of China, Hefei (China). CAS Key Lab. for Urban Pollutant Conversion
  3. Univ. of Science and Technology of China, Hefei (China). CAS Key Lab. for Urban Pollutant Conversion
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division and Biology and Soft Matter Division
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division and Climate Change Science Inst.
Publication Date:
OSTI Identifier:
1319169
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Environmental Pollution
Additional Journal Information:
Journal Volume: 214; Journal Issue: C; Journal ID: ISSN 0269-7491
Publisher:
Elsevier
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES Mercury; methylmercury; permafrost; organic matter; climate warming