title: Warming increases methylmercury production in an Arctic soil.
abstract: Rapid temperature rise in Arctic permafrost impacts not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) toxin that can endanger humans, as well as wildlife in terrestrial and aquatic ecosystems. Currently little is known concerning the effects of rapid permafrost thaw on microbial methylation and how SOC degradation is coupled to MeHg biosynthesis. Here we describe the effects of warming on MeHg production in an Arctic soil during an 8-month anoxic incubation experiment. Net MeHg production increased >10 fold in both organic- and mineral-rich soil layers at warmer (8 °C) than colder (-2 °C) temperatures. The type and availability of labile SOC, such as reducing sugars and ethanol, were particularly important in fueling the rapid initial biosynthesis of MeHg. Freshly amended mercury was more readily methylated than preexisting mercury in the soil. Additionally, positive correlations between mercury methylation and methane and ferrous ion production indicate linkages between SOC degradation and MeHg production. These results show that climate warming and permafrost thaw could potentially enhance MeHg production by an order of magnitude, impacting Arctic terrestrial and aquatic ecosystems by increased exposure to mercury through bioaccumulation and biomagnification in the food web.
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: Ziming
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Fang
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: Xia
authors.initials: X
authors.lastname: Lu
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, China.
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Sheng
authors.affiliation: Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Graham
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Liang
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: Stan D
authors.initials: SD
authors.lastname: Wullschleger
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA. Electronic address: gub1@ornl.gov.
authors.forename: Baohua
authors.initials: B
authors.lastname: Gu
mesh_terms: D001110:Arctic Regions; D001419:Bacteria / Q000378:metabolism; D002244:Carbon / Q000032:analysis; D057231:Climate Change; D017753:Ecosystem; D020387:Food Chain; D046448:Ice Cover; D008767:Methylmercury Compounds / Q000032:analysis* / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D013696:Temperature
chemical_list: D008767:Methylmercury Compounds; D012987:Soil; D012989:Soil Pollutants; D002244:Carbon
keywords: Climate change; Mercury; Methylmercury production; Permafrost; Soil organic carbon