Longitudinal occurrence of methylmercury in terrestrial ecosystems of the Tibetan Plateau.
Methylmercury (MeHg), a neurotoxin, is a global concern because of its potential risk to human and ecological health. Elevated mercury (Hg) concentrations were recently reported in the Tibetan Plateau (TP) due to increasing Hg input from distant regions, yet little is known about MeHg production and distribution in the terrestrial ecosystems of the TP. Here, we report longitudinal occurrence of MeHg and the factors regulating net MeHg production in 23 grassland sites from eastern to western TP. The soil MeHg content varied from 0.002 to 0.058 ng g-1, with different distribution patterns between the eastern and western TP. There was a positive correlation between the MeHg concentration and the longitude after 90 °E, which is similar to the distribution patterns of the total mercury (THg), water and organic carbon in this region. Average MeHg concentration in topsoil is generally higher than that in subsoil. Our results show that MeHg concentration in soils of the TP is directly affected by soil water, potential microbial methylators and THg, while indirectly regulated by soil organic carbon through the microbial community and the longitude-dependent precipitation through soil water. Our study suggests that soil water is the most important driver regulating net MeHg production in the grasslands of the TP. These findings have important implications for unraveling the mechanism of net production of MeHg in high-altitude environments.
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: yrliu@rcees.ac.cn.
Yu-Rong
YR
Liu
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Ji-Xin
JX
Dong
Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China.
Qiang-Gong
QG
Zhang
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Jun-Tao
JT
Wang
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Li-Li
LL
Han
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Jun
J
Zeng
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville 3010, Victoria, Australia.
Ji-Zheng
JZ
He
D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D004784:Environmental Monitoring / Q000379:methods*; D065948:Grassland; D006801:Humans; D008628:Mercury / Q000032:analysis / Q000737:chemistry*; D008767:Methylmercury Compounds / Q000032:analysis* / Q000378:metabolism; D064307:Microbiota / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis*; D018609:Tibet
D008767:Methylmercury Compounds; D012336:RNA, Ribosomal, 16S; D012987:Soil; D012989:Soil Pollutants; D008628:Mercury
High-altitude; Methylmercury; Microbial community; Soil water; Tibetan Plateau