太湖西岸河网沉积物中重金属污染特征及风险评价

为研究太湖西岸河网沉积物中重金属污染特征及风险,调查了丰-平-枯3个水期19个点位8种重金属的含量,结果表明,沉积物中重金属浓度顺序为ZnCrCuPbNiAsCdHg,其中Cd、Cu、Zn、Pb、Ni明显高于其环境背景值,除As外,其余7种重金属平水期含量高于丰水和枯水期.地累积指数(I_(geo))和潜在生态指数(RI)评价表明,研究区沉积物中Cd属于中等污染程度和中等生态风险,Cd对RI贡献率为35%,重金属生物毒性不利影响评价值(mP EC-Q)范围为0.12~0.76,平均值0.30,表明研究区发生生物毒性不利影响的可能性为15%~29%,工业与生活混合区点位S2从污染程度、生态风险、生物毒性不利影响和主成分评价的污染及风险均最大,表现出多种重金属的协同污染,这与其周围污染排放特征一致,为该区域河流沉积物中重金属污染控制提供依据.

Pollution Characteristics and Risk Assessment of Heavy Metals from River Network Sediment in Western Area of Taihu Lake

River sediments is a valuable environmental medium for characterizing contamination of heavy metals in the western areas of Taihu Basin and the associated risks to human health. We collected samples of typical inflow river sediments from nineteen sites during different water periods. The results showed that the concentrations of heavy metals in the river sediments followed the order of Zn > Cr > Cu > Pb > Ni > As > Cd > Hg. Compared to the background concentrations, the mean concentrations of Zn, Cd, Cu, Ni and Pb seriously exceeded the standard values. Except for As, the highest concentrations of heavy metals (Zn, Cr, Cu, Pb, Ni, Cd, Hg) were found in the samples from normal water period. The metal (Cd) presented moderate pollution degree and ecological risks,and the RI value of Cd accounted for about 47% of the total RI value. The mPEC-Q values of the sediments were in the range of 0.12-0.76, and the mean value was 0.3, indicating that the sediments in all of the sampling sites had a 15%-29% probability of toxicity. In terms of the highest value of the heavy metals, higher concentrations, I_geo, mPEC-Q and PCA values were found at the S2 sampling sites. The results showed that effects of synergism of heavy metals pollutants on the point were found in the paper, which will provide scientific basis for control of heavy metal pollution in the Taihu Basin.