长江传统持久性有机污染物的水-气扩散交换通量与机制

Riverine transport represents a relevant component of persistent organic pollutants (POPs) remobilization on local or possibly regional scales, and therefore plays an important role in their distribution and global transport of POPs. Starting with a scientific question that does the Yangtze River (YR) act as a regional sink or source of POPs in the atmosphere, the main objective of this study is to determine the temporal and spatial variation of water-air diffuse exchange flux and its primary controlling factors, focusing on the YR. To our knowledge, the YR outflow is recognized as an important secondary source of contaminants (especially legacy POPs, e.g. organochlorine pesticides and polychlorinated biphenyls) for the coastal area of the East China Sea under conditions of declining primary sources, therefore the study results not only help to update our understanding of the behaviors and fate of POPs in the riverine area, but also are useful to reveal the influence of large river on the distribution and global transport of POPs.

大河作为持久性有机污染物迁移的重要途径之一，在区域乃至全球持久性有机污染物地球化学过程中具有至关重要的作用。本项目立足于“长江是区域持久性有机污染物的源或汇”这一科学问题？围绕长江重点区域，采用“点-线”结合的观测方式，建立长江持久性有机污染物水-气扩散交换通量的时间和空间序列，考察环境参数的时空变化与该污染物水-气扩散交换的响应关系和影响机制，进而揭示其季节性和区域性源汇转换规律与主控因素。项目立意于当前环境中传统持久性有机污染物（有机氯农药和多氯联苯）以二次来源为主，残留污染物的再释放已成为大气中该污染物主要来源的这一背景，研究利用长江区位优势，成果有助于深入理解世界级大河在全球/区域持久性有机污染物源汇效应和环境归趋中所扮演的角色。

项目围绕长江口-东海内陆架POPs环境地球化学开展较为系统的研究，针对长江巨量POPs输入，在径流搬运、大气传输季节性差异与河口-近海POPs大气-水界面过程响应关系方面取得了原创性成果。长江口和东海内陆架作为陆海交互的关键带，沉积物既是持久性有机污染物的汇也是源，发现长江入海水沙的季节性差异，主导了河口-近海持久性有机污染物水-气界面交换方向和通量，进而控制其源汇关系转化。传统持久性有机污染物（DDTs和PCBs）从一次污染源到二次释放源的转变，发现长江流域夏季地表径流量大，土壤中残留污染物通过径流搬运入海，并经大气挥发重新进入大气，成为河口区域大气中污染物的重要来源。项目至今已发表SCI论文9篇，中文核心2篇；第一手核心数据可以作为我国东部POPs陆源排放与主要陆架环境汇之间的定量关系研究的主要支撑。