洞庭湖平原中小型湖群沉积物铬污染特征与评价

于2007年采集洞庭湖平原地区10个中小型湖泊沉积物样品33个(其中表层样品29个,柱状样品4个),对沉积物重金属元素Cr的空间分布特征及其污染等级进行研究. 各湖泊表层沉积物中w(Cr)普遍高于环境背景值,其w(Cr)平均值排序为岳阳南湖>大通湖>珊珀湖>东湖>黄盖湖>安乐湖>北民湖>柳叶湖>毛里湖>芭蕉湖. 各湖柱状沉积物中w(Cr)由底层到表层的垂向上呈现不同的波动趋势. 各湖沉积物的铬污染程度按湖泊类型划分,表现为城市湖泊>投肥养殖型湖泊>人放天养型湖泊. 地累积指数法评价结果显示,洞庭湖平原地区中小型湖群沉积物中铬污染较轻,4个湖泊的10个采样点为偏中度污染,9个湖泊18个采样点为轻度污染,1个采样点没有污染. 

Characteristics and Evaluation of Chromium Pollution in the Sediments of Medium-Small Size Lake Groups in Dongting Lake Plain

The spatial distribution characteristics and degree of chromium pollution in 33 sediment samples collected in 2007 in different functional districts of ten medium-small size lakes in Dongting Lake Plain were evaluated. The samples included 29 superficial sediment samples and four cores samples. The results showed that the concentrations of chromium in the superficial sediments were arranged in the order: Yueyangnanhu Lake>Datong Lake>Shanpo Lake>Dong Lake>Huanggai Lake>Anle Lake>Beimin Lake>Liuye Lake>Maoli Lake>Bajiao Lake, and were generally higher than the environmental background levels. Among different lakes, the samples showed different fluctuation tendencies of the content of chromium in the sediment cores from the bottom to the surface in the vertical direction. Our findings also suggested that the decreasing order of the degree of chromium pollution in the lake sediments based on the type of lake was as follows: urban lakes>fertilizer breeding lakes>non-fertilizer breeding lakes. Results of integrated indexing of geoaccumulation showed that the chromium pollution in the sediments from medium-small size lake groups in Dongting Lake Plain were at a low level: ten points in four lakes for the degree of pollution level Ⅱ, 18 points in nine lakes for the level Ⅰ, and one point for the level 0.