江苏省浅水湖泊表层沉积物重金属GIS空间分布及生态风险评价

为了解江苏省内浅水湖泊表层沉积物中重金属污染情况,对该省内11个湖泊表层沉积物进行采样,测定了As、Cr、Cu、Pb、Zn、Ni这6种重金属的含量.利用GIS对重金属进行空间分布分析,并采用地累积指数法、改进的污染指数法、污染负荷法和潜在生态风险指数法对沉积物中重金属污染情况进行评价.结果表明,研究湖泊表层沉积物中,As、Cu、Zn、Cr、Pb、Ni平均含量占江苏省土壤背景值的倍数分别为1.74~3.85、0.65~2.66、0.48~3.56、0.43~1.52、0.02~1.49和0.12~1.42,根据地累积指数法和潜在生态风险单项金属评价结果,As为主要污染物,不仅富集程度高而且具有较大的潜在生态风险,Cu次之,其余几种重金属污染程度相对较轻.综合几种评价方法的结果,三氿湖、高邮湖、邵伯湖表层沉积物中重金属污染情况相对最严重,污染负荷最大,潜在生态风险达到中等程度;滆湖、白马湖、洪泽湖表层沉积物中部分区域存在某些金属的污染,整体污染有加重趋势,沉积物中重金属污染负荷较大,潜在生态风险达到中等程度;其余5个湖泊,沉积物受重金属污染的风险以及污染负荷均较小,整体为无污染状态.

GIS Spatial Distribution and Ecological Risk Assessment of Heavy Metals in Surface Sediments of Shallow Lakes in Jiangsu Province

To understand pollution of heavy metals in surface sediments of shallow lakes, surface sediments samples of 11 lakes in Jiangsu province were collected to determine the content of six heavy metals including As, Cr, Cu, Pb, Zn and Ni. GIS was used to analyze the spatial distribution of heavy metals, and geological accumulation index (I_geo), modified contamination index (mC_d),pollution load index (PLI) and potential ecological risk index (RI) were used to evaluate heavy metal contamination in the sediments. The results showed that: in the lakes' surface sediments, the average content of As, Cu, Zn, Cr, Pb, Ni in multiples of soil background of Jiangsu province were 1.74-3.85, 0.65-2.66, 0.48-3.56, 0.43-1.52, 0.02-1.49 and 0.12-1.42. According to the evaluation results of I_geo and RI, As, which had high degree of enrichment and great potential ecological risk, was the main pollutant, followed by Cu, and pollution of the rest of heavy metals was relatively light. Combining the results of several evaluation methods, in surface sediments of Sanjiu Lake, Gaoyou Lake and Shaobo Lake, these heavy metals had the most serious pollution, the maximum pollution loading and moderate potential ecological risk; in surface sediments of Gehu Lake, Baima Lake and Hongze Lake, some regions were polluted by certain metals, the overall trend of pollution was aggravating, the pollution loading was large, and the potential ecological risk reached moderate; in the other 5 lakes, the risk of sediments polluted by heavy metals, as well as the pollution loading, was small, and the overall was not polluted.