Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing, 100101, China.
State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing, 100101, China; University of the Chinese Academy of Sciences, Beijing, 100049, China.
Environ Pollut. 2020 Jan;256:113432. doi: 10.1016/j.envpol.2019.113432. Epub 2019 Oct 18.
The concentration and isotopic composition of mercury (Hg) were studied in frozen soils along a southwest-northeast transect over the Himalaya-Tibet. Soil total Hg (Hg) concentrations were significantly higher in the southern slopes (72 ± 54 ng g, 2SD, n = 21) than those in the northern slopes (43 ± 26 ng g, 2SD, n = 10) of Himalaya-Tibet. No significant relationship was observed between Hg concentrations and soil organic carbon (SOC), indicating that the Hg variation was not governed by SOC. Soil from the southern slopes showed significantly negative mean δHg (-0.53 ± 0.50‰, 2SD, n = 21) relative to those from the northern slopes (-0.12 ± 0.40‰, 2SD, n = 10). The δHg values of the southern slopes are more similar to South Asian anthropogenic Hg emissions. A significant correlation between 1/Hg and δHg was observed in all the soil samples, further suggesting a mixing of Hg from South Asian anthropogenic emissions and natural geochemical background. Large ranges of ΔHg (-0.45 and 0.24‰) were observed in frozen soils. Most of soil samples displayed negative ΔHg values, implying they mainly received Hg from gaseous Hg(0) deposition. A few samples had slightly positive odd-MIF, indicating precipitation-sourced Hg was more prevalent than gaseous Hg(0) in certain areas. The spatial distribution patterns of Hg concentrations and Hg isotopes indicated that Himalaya-Tibet, even its northern part, may have been influenced by transboundary atmospheric Hg pollution from South Asia.
本研究沿喜马拉雅山-青藏高原的西南-东北向横剖面对冻结土壤中的汞（Hg）浓度及其同位素组成进行了研究。青藏高原南坡土壤总汞（Hg）浓度明显高于北坡（72±54ng g，2SD，n=21）（43±26ng g，2SD，n=10）。Hg 浓度与土壤有机碳（SOC）之间无显著相关性，表明 Hg 的变化不受 SOC 控制。南坡土壤的平均 δHg 值明显为负（-0.53±0.50‰，2SD，n=21），而北坡土壤的 δHg 值明显为正（-0.12±0.40‰，2SD，n=10）。南坡的 δHg 值与南亚人为 Hg 排放更为相似。所有土壤样品中均观察到 1/Hg 与 δHg 之间存在显著相关性，进一步表明南亚人为 Hg 排放与自然地球化学背景之间存在 Hg 的混合。在冻结土壤中观察到较大范围的 ΔHg（-0.45 和 0.24‰）。大多数土壤样品显示出负的 ΔHg 值，表明它们主要从气态 Hg(0)沉降中获得 Hg。少数样品的奇数 MIF 略有为正，表明在某些地区，沉降源 Hg 比气态 Hg(0)更为普遍。Hg 浓度和 Hg 同位素的空间分布模式表明，喜马拉雅山-青藏高原，甚至其北部地区，可能受到来自南亚的越境大气 Hg 污染的影响。
