钱塘江沉积物重金属污染源解析及生态风险评价

Source Identification and Ecological Risk Assessment of Heavy Metals in Sediments of Qiantang River

在钱塘江(杭州段)水系的13个采样点采集沉积物样品,分析重金属(Zn、Cr、Cd、Cu、Pb、As、Mn和Fe)的来源并进行了生态风险评价。结果显示,各重金属的浓度平均分别为:Zn 223.76 mg/kg,Cr 73.16 mg/kg,Cd 2.50 mg/kg,Cu 103.73 mg/kg,Pb 46.58mg/kg、As 11.91 mg/kg、Mn 736.4 mg/kg、Fe 2.71×10~4mg/kg。除Mn、Fe以外,其他6种重金属平均含量均超出世界沉积物中重金属的背景值。相关性分析,主成份分析和聚类分析结果显示,Cr、Pb、Cu、As、Zn和Cd主要来源是工业废水排放和化石燃料燃烧。Mn和Fe主要来源是自然环境。地积累指数结果显示各重金属污染程度排序:Cd>Cu>Pb>Zn>As>Cr>Mn>Fe,其中Zn,Pb和As的污染程度为1级(轻度污染),Cu的污染程度为2级(偏中度污染),Cd的污染程度为4级(偏重污染)。单因子潜在生态风险指数结果显示各重金属对生态风险构成危害的顺序为Cd>Cu>As>Pb>Zn>Cr,综合潜在生态风险指数等级显示为强生态风险。人类活动特别是工业生产是造成钱塘江底泥污染的主要原因。

Sediment samples were collected from 13 sites from Qiangtang River（Hangzhou Section）to investigate the sources of heavy metals such as Zn, Cr, Cd, Cu, Pb, As, Mn and Fe, and to assess their ecological risk. The average concentrations of heavy metals in surface sediments were found to be as Zn 223.76 mg/kg,Cr 73.16 mg/kg, Cd 2.50 mg/kg, Cu 103.73 mg/kg,Pb 46.58 mg/kg, As 11.91 mg/kg, Mn 736.4 mg/kg and Fe 2.71×10-4 mg/kg. The average concentrations of Zn, Cr, Cd, Cu, Pb and As were higher than the background sediments of the world. Correlation analysis, principal component analysis and clus-ter analysis indicated that Cr, Pb, Cu, As, Zn and Cd mainly originate from industrial wastewater and combustion of fossil fu-el, while Mn and Fe are mostly derived from natural sources. Ecological risk assessment was undertaken using the geoaccu-mulation index（I（geo）） and the potential ecological risk index（PERI）. The I（geo）values of these metals followed the sequence CdCuPbZnAsCrMnFe. The calculated average I（geo）values showed samples remained in class 1（unpolluted to moderately polluted） with respect to Zn, Pb and As, in class 2（moderate pollution） with respect to Cu, and in class 4（severe polluted）with respect to Cd. The average potential ecological risk was ranked as CdCuAsPbZnCr. The average RI for the entire study area indicated the presence of a high ecological risk. Anthropogenic activities, especially industrial activity, were the main reason for heavy metal pollution in sediment of Qiantang River.