Sun Shiwei, Kang Shichang, Huang Jie, Chen Shengyun, Zhang Qianggong, Guo Junming, Liu Wenjie, Neupane Bigyan, Qin Dahe
Qilian Shan Station of Glaciology and Ecologic Environment, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2017 Jun;24(17):15078-15088. doi: 10.1007/s11356-017-9088-0. Epub 2017 May 10.
The Tibetan Plateau (TP) is home to the largest permafrost bodies at low- and mid-latitudes, yet little is known about the distribution and variation of mercury (Hg) in frozen soil of the permafrost regions. In this study, extensive soil sampling campaigns were carried out in 23 soil pits from 12 plots in a high-altitude permafrost region of the Shule River Basin, northeastern TP. Hg distribution, variation, and their dependences on soil properties were analyzed. The results have revealed that total Hg (THg) concentrations were low ranging from 6.3 to 29.1 ng g. A near-surface peak of THg concentrations followed by a continuous decrease were observed on the vertical profiles of most soil pits. Significant positive relationships among THg concentrations, soil organic carbon (SOC) contents, and silty fractions were observed, indicating that SOC content and silty fraction are two dominant factors influencing the spatial distribution of THg. THg concentrations in soils showed a decreasing trend with altitude, which was probably attributed to a lower soil potential to Hg accumulation under the condition of lower SOC contents and silty fractions at high altitudes. Approximately, 130.6 t Hg in soils (0-60 cm) was estimated and a loss of 64.2% of Hg from the highly stable and stable permafrost (H-SP) region via permafrost degradation was expected in the upstream regions of the Shule River Basin, indicating that the large areas of permafrost regions may become an important source of global Hg emission as a result of the ongoing widespread permafrost degradation.
青藏高原是中低纬度地区最大的冻土区，但人们对该地区冻土中汞（Hg）的分布和变化知之甚少。本研究在青藏高原东北部疏勒河流域高海拔冻土区的12个样地的23个土坑中进行了广泛的土壤采样。分析了汞的分布、变化及其与土壤性质的关系。结果表明，总汞（THg）浓度较低，范围为6.3至29.1纳克/克。在大多数土坑的垂直剖面上，观察到总汞浓度在近地表处出现峰值，随后持续下降。总汞浓度、土壤有机碳（SOC）含量和粉质组分之间存在显著正相关关系，表明土壤有机碳含量和粉质组分是影响总汞空间分布的两个主要因素。土壤中的总汞浓度随海拔升高呈下降趋势，这可能是由于高海拔地区土壤有机碳含量和粉质组分较低，土壤汞积累潜力较低所致。据估算，疏勒河流域上游地区土壤（0-60厘米）中约有130.6吨汞，预计随着多年冻土的持续退化，高稳定和稳定多年冻土（H-SP）区域将损失64.2%的汞，这表明大面积的多年冻土区域可能因持续广泛的多年冻土退化而成为全球汞排放的重要来源。
