长江江苏段沉积物中重金属与底栖动物调查及生态风险评价

Investigation of Heavy Metals and Zoobenthos in Jiangsu Section of the Yangtze River and Ecological Risk Assessment

对长江江苏段沉积物样品中Cr、Cu、Pb、Zn、Hg和As含量进行测定,同时对底栖动物进行调查,采用H9kanson生态风险指数法对重金属进行潜在生态风险评价,并用Wright寡毛类密度法评价长江江苏段水质。结果表明,长江江苏段6种元素的潜在生态风险因子大小顺序为Hg>As>Pb>Cu>Cr>Zn,其中Hg是最主要的生态风险贡献因子。潜在生态风险评价指数和Wright生物指数之间呈极显著性相关(r=0.91,n=7,α=0.01),Hg浓度与颤蚓科寡毛类底栖动物密度也存在显著的相关性。这说明颤蚓寡毛类可以作为重金属污染尤其是Hg污染的潜在指示生物,潜在生态风险评价指数可较好地反映沉积物的生态风险。综合潜在生态风险评价和底栖生物指数评价,长江江苏段总体水质良好至轻微污染,但位于悬浮物易沉降地区的靖江采样点为中等污染。

Determination of Cr, Cu, Pb, Zn, Hg and As in 7 surface sediment samples and investigation of zoobenthos at the same sites, both collected in Dec. 2004, were conducted in Jiangsu section of the Yangtze River. Then Hakanson＇ s ecological risk index method was applied to assess the potential risk of the heavy metals. Wright biotic index of zoobenthos was used as indicator of water quality in Jiangsu section of the Yangtze River. The pollutants in order of impacting extent of ecological risk were： Hg〉As〉Pb〉Cu〉Cr〉Zn, and Hg was the most hazardous element in Jiangsu section of the Yangtze River. Significant correlation between Hǎkanson＇ s ecological risk index and Wright biotic index （r=- 0.91, n=7, a=0.01） suggested that potential ecological risk index was a practical method for ecological risk evaluation of the heavy metals in sediments. The degree of contamination and potential ecological risk of Jiangsu section of the Yangtze River were low except that of Jingjiang, a deposition zone, was moderate.