三峡库区水体多氯联苯污染特征与环境交换

为了掌握三峡库区水体多氯联苯环境污染状况,在长江三峡库区分两次采集了91件水体样品,并用气相色谱(GC-ECD)内标法分析了多氯联苯(PCBs)的含量,研究了三峡库区水体中PCBs的残留水平及其环境交换。结果表明:库区水体中PCBs的含量范围为N.D.～48.67ng/L,均值为24.34ng/L(共31种),最大值出现在朝天门,为48.67ng/L;干流断面采样点PCBs的含量仅有一个点位超过了《地表水水质标准》(GB3838—2002)标准,超标倍数为1.16倍;长江支流PCBs的分布特征是,与嘉陵江有关的采样点PCBs的含量都相对较高,其次是大宁河,但与嘉陵江同等级的乌江其含量却很低;水库中PCBs的环境交换主要集中在被淹没的土壤与库区水体之间,因此三峡大坝的蓄水和冲砂会使曾经被吸附的PCBs释放出来,导致库区水体中PCBs的含量增加。

PCBs Pollution and Environmental Exchange in Three Gorges Reservoir Area

91 water samples are collected from Three Gorges Reservoir area and the concentration of PCBs in the samples is determined by GC-ECD with the internal standard method so as to study the residue levels and environment exchange of PCBs in the water of the study area.The results show that water column PCBs content is ND~48.67 ng/L,the mean being 24.34 ng/L(31 kinds) and the maximum being 48.67ng/L in Chaotianmen section.The total content of PCBs in the mainstream sections of sampling points is only one point more than that required by The Surface Water Quality Standards(GB3838—2002),exceeding a multiple of 1.16 times.For the situation of the Yangtze River tributaries,PCBs content in the Jialing River sampling points is relatively high,and it is the second highest in the Daning River though it is very low in the Wujiang River.PCBs environment exchange occurs between the submerged soil and water in the reservoir area.The adsorption of PCBs will be released,so the PCBs content in the water body will increase.