开封市污灌区土壤重金属污染及潜在生态风险评价

Heavy Metal Pollution and Potential Ecological Risk Assessment in Sewage Irrigation Area of Kaifeng City

对开封市惠济河污灌区土壤中重金属Pb、Cd、Hg、As、Cr、Cu、Zn、Ni的含量进行测定,并采用单因子污染指数法、综合污染指数法和潜在生态危害指数法对该区域土壤重金属污染状况及潜在生态风险进行评价,以期为今后污灌土壤治理和修复提供理论依据。结果显示,污灌区土壤中重金属Cu、Zn、Pb、Cd、Hg、As、Cr、Ni含量平均值分别为62.9、127.0、82.6、0.62、0.148、16.0、53.2、27.2mg/kg,仅Cd含量稍微超过土壤环境质量(GB 15618—1995)二级标准,其余7种重金属含量均未超标。从单因子污染指数来看,Cu、Zn、Pb、Hg、As、Cr、Ni的单因子污染指数平均值均未超过1,说明土壤未被这些重金属污染,Cd的单因子污染指数为1.033,说明土壤被Cd轻微污染。从综合污染指数来看,污灌区土壤重金属的综合污染指数平均值为0.827,总体处于警戒线水平。从潜在生态风险因子和指数来看,污灌区所有重金属总体均具有轻微生态风险。另外,单因子污染指数分析发现,河流水质、河流底质、污灌区土壤中的首要污染因子相同,均为Cd,且前3项污染因子中均含有Cu;河流水质、污灌区土壤中的前3项污染因子均含有As,说明污灌区土壤中的污染因子与河水、河流底质中的污染因子基本相同,土壤中重金属污染主要是由多年的污水灌溉造成的。

The heavy metal contents of Pb, Cd, Hg, As, Cr, Cu, Zn, Ni were measured in Huiji river sewage irrigated area in Kaifeng, and the methods of single factor pollution index, comprehensive index and potential ecological risk index were used to evaluate soil heavy metal pollution and potential ecological risk in the sewage irrigation of Kaifeng, so as to offer evidence for control and remedy techniques of contaminated soils. The results showed that the mean contents of Cu , Zn , Pb , Cd, Hg, As , Cr and Ni in the sewage irrigation were 62. 9,127.0,82. 6 ,0. 62 ,0. 148 16. 0 ,53. 2 ,27. 2 mg/kg,except of Cd,the remaining 7 heavy metals contents were all below the second standard of soil environmental quality standards（GB 15618-1995） . Seen from the single factor pollution index,the single factor pollution index means of Cu, Zn, Pb, Hg, As, Cr and Ni were all less than 1 , which represented that the soil was not polluted by these heavy metals,the single factor pollution index of Cd was 1.033 indicating the soil was slightly polluted by Cd. Seen from comprehensive index,the average comprehensive pollution index of soil heavy metal was 0. 827 , indicating the soil was at the warning level. Seen from potential ecological risk factor and index,there was slightly ecological risk in sewage irrigation area for all heavy metals. Besides,through analysis of single factor pollution index, the signifficant pollution factor of water quality of the river, bottom of the river, soil of the sewage irrigated area was the same, which all was Cd,the top three pollution factors all contained Cu; the top three factors of the water quality of the river and soil of the sewage irrigated area all contained As, indicating that the pollution factor of soil was same with that of the water and bottom of the river, and the heavy metal contamination in soil was caused by sewage irrigation.