喜马拉雅山中段大气颗粒态汞时空特征及其来源研究

Mercury (Hg) is a globally distributed hazardous contaminant due to its unique physical and chemical properties. The atmospheric particulate-bound mercury (PBM) is an important composition of atmospheric Hg which plays an significant role in the global biogeochemical cycle of Hg. The Himalayas is located between the South Asian Sub-Continent and the Tibetan Plateau, which is regarded as the key region for the study of long-range transport of PBM that are emitted from urbanized areas of south Asia to the Tibetan Plateau. However, our understanding on transport mechanisms and sources of Hg over the Himalayas and Tibetan Plateau are still sparse. Therefore, in this proposed research, based on the four sampling stations characterizing urban and remote sites across the Himalayas, the atmospheric aerosol (TSP, PM10, PM2.5) will be sampled long-term. The PBM and Hg isotopes will be measured. The temporal and spatial variations and their influencing factors will be systematically analyzed based on the concentration of PBM and meteorological data. Furthermore, the sources of PBM will be identified using Hg isotopes, air mass backward trajectories and Potential source contribution function (PSCF). This proposed research will provide basic data for quantitative modeling trans-border transportation of atmospheric Hg from south Asian to the Tibetan Plateau. Most importantly, the proposed research will offer valuable scientific data and knowledge for protecting fragile ecosystem of the Himalayas-Tibetan Plateau region.

汞是一种具有特殊物理化学性质的全球性有毒污染物。颗粒态汞作为大气汞的重要组成形态，在汞污染物生物地球化学循环过程中扮演着重要的角色。喜马拉雅山脉横亘在南亚次大陆和青藏高原之间，是大气颗粒态汞污染物从南亚向青藏高原跨境传输的关键区域。本项目依托喜马拉雅中段跨南北断面的4个野外台站（涵盖排放源区、乡村区和偏远区），持续采集气溶胶样品（TSP、PM2.5、PM10），并测定其大气颗粒态汞浓度和汞同位素组成。结合相关气象参数开展综合分析，明晰大气颗粒态汞浓度水平、粒径分布和时空变化及其主要气象影响因素；并进一步运用汞同位素组成、后向气团轨迹追踪和潜在源贡献因子法（PSCF）等手段揭示喜马拉雅山中段大气颗粒态汞的主要源区。本研究不仅为相关模型量化南亚汞污染物向青藏高原跨境传输提供实测验证数据，亦将为高原生态环境保护提供重要的科学依据和理论支撑。

汞是一种具有特殊物理化学性质的全球性有毒污染物。颗粒态汞作为大气汞的重要组成形态，在汞污染物生物地球化学循环过程中扮演着重要的角色。喜马拉雅山脉横亘在南亚次大陆和青藏高原之间，是大气颗粒态汞污染物从南亚向青藏高原跨境传输的关键区域。本项目依托喜马拉雅中段跨南北2条断面的7个野外台站，持续采集气溶胶样品，并测定其大气颗粒态汞浓度和汞同位素组成。结果表明，跨喜马拉雅山大气颗粒态汞从南至北显著降低，呈季风期低而非季风期高的季节特征。该区域大气颗粒态汞主要受排放源强度、传输和气象条件等影响。利用同位素等证据表明，南亚城市区大气颗粒态汞主要源自局地或区域性排放，而偏远站点主要受长距离传输的影响。在本项目的支持下，共发表研究论文5篇。研究成果不仅为相关模型量化南亚汞污染物向青藏高原跨境传输提供实测验证数据，亦将为高原生态环境保护提供重要的科学依据和理论支撑。