气候变化背景下多年冻土区六六六（HCHs）和多氯联苯（PCBs）的二次排放

Environmental fate of persistent organic pollutants (POPs) under climate change has become an international research focus, among which, the effect of temperature on secondary emissions of POPs in the environmental media is probably the most important effect and stronger than any other effect of climate change on the environmental cycling of POPs. It has been evidenced by many published data that, due to the Global Warming, the permafrost region has decreased and permafrost is melting; there is no systematic study on the pollution levels, migration and transformation of POPs in the high-latitude permafrost of China boreal forest which has been as a sink of POPs. The objectives of this research are to investigate the residue concentrations and composition characteristics of 2 typical POPs, HCHs and PCBs, in the permafrost region by concurrently collecting multimedia samples, including air, water, soil core, and analyzing these 2 POPs in these media; to analyze the impact of climate change to POPs contamination via changes in redistribution and transport processes; and in particular, to study the mechanism of the secondary emissions of POPs from the permafrost soil caused by temperature increase. The proposed research not only has great scientific significance for understanding the source-receptor transition and environmental fate, and the secondary emission in particular, of POPs under climate change in permafrost area as a new source, accumulated for many decades when permafrost acted as a sink, but will provide a scientific basis for the implementation of the Stockholm Convention on Persistent Organic Pollutants and the development of relevant pollution control policies of POPs in China, and the protection of high-latitude permafrost ecosystems and permafrost wetlands habitat as well.

气候变化背景下持久性有机污染物（POPs）的环境归趋已成为国际研究热点，其中最重要的可能是温度对环境介质中POPs二次排放的影响。大量资料表明，全球变暖导致多年冻土消融和退缩强烈，然而作为POPs汇的我国高纬度多年冻土区POPs的污染现状和迁移转化规律及其二次排放还没有开展系统的研究。本课题研究的目的是了解两种典型POPs--六六六（HCHs）和多氯联苯（PCBs）在多年冻土区的残留浓度和组成特征；研究气候变化对多年冻土区环境介质中POPs重新分配和迁移转化的影响；重点分析气候变暖情况下，多年冻土中POPs进行二次排放的机理。本研究对了解气候变化背景下累积在多年冻土中的POPs的源汇转换和环境归趋，特别是二次排放，具有重要的科学意义；研究成果将为我国履行《关于持久性有机污染物的斯德哥尔摩公约》、制定相关的POPs污染控制政策、保护高纬度多年冻土区的生态系统和冻土湿地生境提供科学依据。

在高纬度多年冻土区（大兴安岭）建立了POPs 长期监测系统，采集了深度为2米的多年冻土分层土壤样品。检测分析多年冻土样品中的有机氯农药（OCPs）和多环芳烃（PAHs）残留浓度。分析了多年冻土土壤有机质垂直分布规律，发现多年冻土层的存在影响土壤有机质的分布。通过对多年冻土分层土壤样品中有机氯农药（OCPs）分析，阐释多年冻土区OCPs的累积规律和垂直分布特征，分析与水分、有机质含量的关系。分析多年冻土中多环芳烃（PAHs）浓度分布规律，阐述影响多年冻土中PAHs累积和迁移转化的影响因素。本研究结果对了解气候变化背景下累积在多年冻土中的POPs 的源汇转换和环境归趋具有重要的科学意义；研究成果将为我国履行《关于持久性有机污染物的斯德哥尔摩公约》、制定相关的 POPs 污染控制政策、保护高纬度多年冻土区的生态系统和冻土湿地生境提供科学依据。