南亚大气污染物跨境传输及其对青藏高原冰冻圈环境的影响

Atmospheric pollutants have been exerting significant by atmospheric circulation which impacts on global environment. Being adjacent to South Asia, a region with the most intensive air pollution emissions in the world, the Tibetan Plateau are readily influenced by trans-boundary atmospheric pollutants that affect its vulnerable environments, particularly the cryospheric environments. In this project, based on the comprehensive trans-boundary atmospheric pollutants monitoring network (including 20 stations across Himalayas and Karakorum) and cryospheric monitoring stations (8 glaciers selected) we have established in the Tibetan Plateau, integrated approaches (e.g., monitoring, modeling and assessment) will be employed. With the systematic observation and analysis on the composition of air pollutants, including black carbon, heavy metal, and organic substances, combined with the information achieved by atmospheric chemistry models and fingerprint characteristics of isotopes, this project is aiming to reveal the sources, transport pathway and strength of atmospheric pollutants transported into the Tibetan Plateau from South Asia. Furthermore, the temporal/spatial variations as well as the transformation of these pollutants are expected to be elucidated in the cryospheric region. Impacts of light-absorbing impurities on glacier and snow cover will be quantified. Eventually, the risks of “second toxic pollutants emission” on ecological environment due to accelerating melt of glacier/snow cover will be assessed. Overall, the research results are expected to provide valuable and fundamental scientific basis for the regional environmental protection and policy making, as well as superiority for China's environmental diplomacy.

大气污染物通过大气环流传输扩散对全球环境产生了重要影响。青藏高原自身人类活动极为微弱，受西风环流和南亚季风的影响，毗邻的南亚地区大气污染物可以跨境输入高原并对其生态环境，尤其是冰冻圈环境产生影响和危害。本项目依托跨越喜马拉雅山脉和喀喇昆仑山脉的大气污染物和冰冻圈环境集成观测网络，包括20个大气观测台站和8个典型冰川区，以“观测-模拟-评估”为主线，通过对跨境大气污染物（黑碳、有机碳、重金属、有机物等）的系统监测及化学指标测试，结合大气化学模型与同位素指纹特征，明晰南亚大气污染物跨境输入高原的路径、规模及其来源；揭示大气污染物在冰冻圈的时空格局和迁移转化，定量评估大气污染物对青藏高原冰川（积雪）消融的影响；系统评估冰川（积雪）快速消融过程中有毒污染物的“二次释放”及其对生态环境的潜在风险。本项目将为青藏高原环境保护和政策制定提供科学参考，为我国的环境外交谈判提供话语权和主动权。

南亚排放大气污染物可随大气环流跨境传输进入青藏高原，并对其环境尤其是冰冻圈环境产生影响和危害。本项目依托覆盖第三极地区的大气污染物和冰冻圈变化协同观测研究网络，以“观测-模拟-评估”为主线，通过对典型跨境大气污染物（黑碳、有机碳、重金属和有机污染物等）的长期系统监测及化学指标分析，结合大气化学模型与同位素指纹特征，明晰南亚大气污染物跨境输入高原的路径、规模及其来源；揭示大气污染物在冰冻圈的时空格局和迁移转化，定量评估大气污染物对青藏高原冰川/积雪消融的影响；系统评估冰川/积雪快速消融导致有毒污染物“二次释放”及其对生态环境的潜在影响。在项目资助下发表研究论文127篇，专著2部，2名骨干获得基金委优秀青年基金资助，6人获得职称晋升，培养研究生和博士后17名。取得重要成果包括：1）系统阐明了青藏高原及周边地区典型大气污染物（有机碳、黑碳和汞等）的本底含量和时空变化及其来源，南亚地区大气污染物浓度显著高于高原，呈现季风期低非季风期高的季节变化特征，生物质燃烧对污染物的贡献较高；2）揭示了南亚大气污染物跨境输入青藏高原的过程和规模，南亚排放对青藏高原大气黑碳的贡献最大，在非季风期达到61.3%，且主要通过深对流高空翻越和山谷输送两种形式跨境输入青藏高原；3）量化评估显示南亚排放黑碳可导致青藏高原大部地区升温0.1-0.5℃，还可通过直接消融（7.5%）和间接减少降水补给（6.1%）两种形式加速高原冰川消融；4）强调了污染物对冰冻圈补给环境的影响，指出冰冻圈快速消融可释放历史大气污染物（如汞等），对下游水体、生态环境具有潜在危害；5）优化和探索了高寒偏远地区大气雪冰中碳质气溶胶不同组分含量和吸光特性的采样分析方法。本项目成果可为青藏高原环境保护和政策制定提供科学参考，为我国的环境外交谈判提供话语权和主动权。