尼泊尔大气持久性有机污染物的污染特征与跨喜马拉雅传输

South Asia is one of the important emission regions for persistent organic pollutants (POPs). The global dispersion of pollutants from South Asia, driven by atmospheric circulation, is focused widely. By now, there is no emission inventory of POPs in Nepal, which shares the Himalayas with China. The studies focusing on the environment processes during the atmospheric transport haven’t referred to the regions from South Asia to the Tibetan Plateau. What roles do the Himalayas play on the trans-boundary transport? How do the atmospheric POPs transport through the Himalayas? The observation on both the northern and the southern slopes of the Himalayas may favor to answer these issues. The current study will conduct systematic survey based on observation stations and sampling transects with the altitude between 100 meters and 5000 meters on the southern/northern slopes of the Himalayas. The research content includes: 1) to investigate the spatial/seasonal distribution of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated biphenyl ethers (PBDEs) in air and wet/dry deposition; to diagnostic the local emission sources on the southern slope of the Himalayas; to reveal the characteristic and pathway of trans-Himalayas transport based on the comparison between the slopes; to estimate the environmental behavior and fluxes during the POPs transport using Level III fugacity model. These studies will improve the understanding of the POPs trans-boundary transport from South Asia to the Tibetan Plateau, and provide more scientific supporting for inter-governmental negotiation of ‘Stockholm Convention on Persistent Organic Pollutants’.

南亚是全球持久性有机污染物（POPs）的重要源区，大气环流驱动下的南亚污染物的全球扩散已受到广泛关注。然而，目前与我国一山相隔的尼泊尔的POPs污染排放特征及其跨越喜马拉雅向我国青藏高原传输的环境过程尚不明确。喜马拉雅山在POPs传输过程中起到什么作用？POPs通过什么途径跨越喜马拉雅山？针对喜马拉雅南北坡的综合观测将有助于解答上述问题。本研究拟建立包含定位站和环境断面的喜马拉雅南北坡综合观测体系（海拔<100-5000 m），观测大气及沉降中的有机氯农药、多氯联苯和多溴联苯醚的时空分布特征，获得南坡尼泊尔低海拔地区POPs的排放特征和北坡高海拔地区POPs的沉降特征；探讨大气POPs沿山谷跨越喜马拉雅的传输过程；使用逸度模型模拟传输过程中POPs的环境行为，定量POPs跨境迁移通量。上述研究将部分量化POPs自尼泊尔向青藏高原的跨境传输，为我国《斯德哥尔摩公约》履约提供直接依据。

持久性有机污染物（POPs）可随季风自南亚进入青藏高原，但“POPs跨越喜马拉雅的通量和机制”这一科学问题一直是研究难点。项目负责人团队针对该科学问题搭建了包括用于排放源观测、跨喜马拉雅大气传输观测和大气POPs季节变化观测三大子网络的跨喜马拉雅POPs观测网络，进行了系列研究工作，主要成果包括：.1）.对喜马拉雅南坡大气POPs时空分布和排放源进行了研究，发现南亚依然大量存在着POPs的使用和排放，并首次报道了蔬菜保存与运输阶段的六六六使用源；.2）.对喜马拉雅北坡大气POPs季节变化的研究发现，喜马拉雅山是阻碍POPs传输并造成北坡POPs季节峰值自东向西延后的主要原因；.3）.开发了不受风速影响且适用于山区的XAD被动采样器，从而使被动采样器由半定量走向定量，具备成为环境监测常规工具的潜力；.4）.开发了高空间分辨率的MCMPOP模型，基于观测和模拟探讨了POPs跨喜马拉雅传输的过程、机制，揭示了沿河谷传输在跨喜马拉雅传输中的重要作用，并估算出POPs跨喜马拉雅传输的总量为2-100吨/年。.总之，本项目对于南亚POPs来源、传输过程和喜马拉雅的屏障作用进行了深入探讨，并发明了更为精确的观测工具。为POPs迁移转化研究提供了新的思路，拓展了POPs研究的知识边界。.上述成果共发表SCI论文15篇，其中包括环境科学领域顶级期刊Environmental Science & Technology文章2篇、大气化学顶级期刊Atmospheric Chemistry and Physics文章1篇，其他文章亦发表于环境领域重要期刊。

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