三峡水库消落带周期性干湿交替影响下持久性有机污染物的环境地球化学行为

The persistent organic pollutants have been a class of ubiquitous pollutants in the area of Three-Gorges Reservoir. The hydro-fluctuation belt shifts cyclically between wetting and drying by the operation of the reservoir, and thus environmental multimedia properties and the equilibrium of POPs in phases are changed. The hydro-fluctuation belt of Three-Gorges Reservoir turns to be a large-scale experimental field for environmental geochemistry study. This project plans to carry out a case study on the environmental geochemistry behaviors of the POPs in a typical hydro-fluctuation belt area located in Zhongxian County in the reservoir area. According to the reservoir operation stage, the field survey will be performed during years when the soil (sediment), water, and plant leafs will be collected in the study area. The POPs in these environmental media will be analyzed. The aim of this study is to survey the temporal and spatial distribution of the POPs in the hydro-fluctuation belt and find the dynamic environmental behaviors of the POPs influenced by the cyclical alteration of the wetting and drying of the hydro-fluctuation belt. The study will also include serials of laboratory emulations to certain units of the field environment, to evaluate the transport of the POPs among the environmental multimedia of the hydro-fluctuation belt, and to investigate the natural degradation and fate of the POPs in the hydro-fluctuation belt.

持久性有机污染物（POPs）已成为三峡库区广泛分布的污染物，而库区水库消落带经历着强烈的周期性干湿交替，改变了POPs的赋存环境和多介质界面平衡，使得三峡水库消落带成为了研究POPs迁移、转化和归趋之独特的研究综合体和大型环境地球化学实验场。本项目拟选择三峡水库忠县段典型性消落带开展POPs的环境地球化学行为研究，按水库运行阶段进行现场调查、采集研究区消落带土壤（沉积物）、水体及植物叶片并开展测试分析，掌握典型POPs在库区消落带多种环境介质中的时空分布，探讨消落带周期性干湿交替影响下的POPs在多介质环境中的地球化学动态；结合室内模拟实验，探讨POPs在消落带多种环境介质中的迁移及其影响因素，并探究POPs在典型库区消落带系统的自然降解过程与归趋。

三峡库区的水位周期变化为研究持久性有机污染物（POPs）的环境行为提供了大型的实验观测场。库区消落带从低水位线至高水位线记录了不同的淹没-出露环境，区域土壤与江水、大气、生物间发生了不同程度的接触和交流，进而影响着POPs在三峡库区的含量和分布。本项目主要研究目标为消落带土壤（沉积物）中的有机氯农药（OCPs）、多氯联苯（PCBs）和多环芳烃（PAHs）三类POPs，在三峡库区沿江区县中自重庆长寿至湖北秭归设置在各区县内设置剖面，各个剖面分水位线、分土壤层位采集样品进行分析。采用气相色谱-三重四极杆串联质谱（GC-QqQ-MS/MS）对样品中三大类POPs开展检测，结果显示在禁用多年后有机氯农药总体上呈残留水平、多氯联苯类含量较低，而多环芳烃属持续输入源。POPs在剖面间、水位线间和土层间的含量存在不同程度差异；化合物单体在消落带土壤中的分布也有不同程度差异，有些种类的含量和分布与水位线呈显著相关关系。通过进一步数据挖掘，后续讨论将深入至库区消落带中POPs的来源、迁移和转化。相关研究成果可为三峡库区消落带污染防治提供理论依据。