南京市梅雨期雨洪沉积物重金属污染评价

摘要

In order to know the risk of heavy metal element content in sediment of stormwater and the degree of pollution hazard in Nanjing in rainy season,24 samples were obtained and the metal elements of Zn,Pb,Cr,Ni and Cd were measured.Pearson correlation coefficient and combination of factor analysis were used to examine the relationship between various heavy metals in sediments.Methods of cumulative index and potential ecological risk index were used to evaluate the degree of pollution and ecological risk of heavy metals.The results indicated that the mean concentrations of Zn,Pb,Cr,Ni and Cd in sediment of stormwater were 116.64,43.56,86.32,41.13 and 0.32mg/kg,respectively,which were 1.8,1.98,1.14,1.29 and 4.00 times of the Jiangsu soil background values.The index of geoaccumulation analysis results showed that the pollution degree of 5 kinds of heavy metals followed respectively:Cd＞Zn＞Pb＞Ni＞Cr and the Cd、Pb were non-to moderate-pollution and the Cr was of non-pollution.The results of potential ecological risk index analysis showed that single potential ecological risk coefficient Eir of 5 kinds of heavy metals was described in following order:Cd＞Pb＞Ni＞Cr＞Zn.Single potential ecological risk coefficient Eir was less than 40 and potential ecological risk index RI was less than 150.Five kinds of heavy metal in sediment of stormwater all belonged to a light potential ecological risk.The Zn,Pb and Ni mainly came from transportation and people stream.The Cr mainly came from weathering soil and architecture source.The results of this study had important realistic meaning for heavy metal pollution control,environmental quality assessment and the city layout program.%为了了解南京市梅雨季节雨洪沉积物重金属含量及其污染程度的危害,在研究区域内采集24处样品,检测其Zn,Pb,Cr,Ni和Cd共5种重金属元素的含量,用皮尔逊相关系数和组合因子分析探讨雨洪沉积物中各重金属的相关性,并用地累积指数法和潜在生态危险指数法评价其污染程度和生态风险.结果表明:南京市雨洪沉积物中Zn,Pb,Cr,Ni和Cd的质量分数分别为116.64、43.56、86.32、41.13、0.32 mg/kg,分别是江苏省土壤元素背景值的1.8、1.98、1.14、1.29、4.00倍,地累积指数评价结果表明:5种重金属污染程度由强到弱依次为:Cd＞Zn＞Pb＞Ni＞Cr,Cd、Pb处于中度污染,Cr无污染.潜在生态危险指数评价结果表明:单项潜在生态风险系数E从大到小为:Cd＞Pb＞Ni＞Cr＞Zn,5种重金属的单项潜在生态风险系数E＜40,综合潜在生态风险系数除Cd以外,RI＜150,处于轻微潜在生态风险;路面雨洪沉积物中Zn、Pb和Ni主要受交通及人流量影响,Cr主要受土壤风化以及建筑废材影响.研究结果对区域内环境重金属污染的控制、环境评价和城市布局具有指导意义.