武陟县农田土壤重金属污染评价

Pollution Assessment of Heavy Metal Elements in Farmland Soil in Wuzhi County

对武陟县农田表层土壤中的Cr、Ni、Cu、As、Pb含量进行分析,采用单因子污染指数法、内梅罗综合污染指数法、潜在生态危害指数法对该区域农田土壤重金属污染进行评价。结果表明,武陟县农田土壤Cr、Ni、Cu、As、Pb含量分别为70.53、33.65、31.95、16.74、22.04 mg/kg,Cr、Ni、Cu、Pb的单因子污染指数均小于1,只有As在部分土样中存在超标现象,但单因子污染指数均小于2,超标样品比率达到21.28%。重金属内梅罗综合污染指数为0.65,土壤处于安全水平;旱地土壤重金属内梅罗综合污染指数小于水田,说明旱地土壤污染程度轻于水田。5种重金属元素的潜在生态危害指数均值为36.97,处于轻微风险等级。在这5种重金属元素中,As对潜在生态风险的贡献率为39.8%,是最主要的生态风险因子。土壤重金属的相关性分析表明,Cr含量与Ni、Cu、As含量及Ni含量与Cu含量、Cu含量与As含量存在显著或极显著正相关性,说明这5种重金属存在不同程度的复合污染或具有相同的污染来源。

Surface soil samples collected from farmland in Wuzhi county were used to analyze the contents of Cr,Ni,Cu,As and Pb,and the quality of soil was assessed by single factor pollution index method,com-prehensive pollution index method and the potential ecological risk index method. The results showed that the contents of Cr,Ni,Cu,As and Pb in the soil were 70. 53,33. 65,31. 95,16. 74,22. 04 mg/kg,respec-tively. Single factor pollution index of Cr,Ni,Cu and Pb were smaller than one, only 21. 28% of the soil samples could not meet the requirement of national standard in terms of As content,and the single factor pollution index was less than two. However,single factor pollution index of As was smaller than 2. The comprehensive pollution index was 0. 65,indicating that the soils had not been polluted, was safe. Com-prehensive pollution index of dry land was smaller than that of paddy field,showing that the pollution sta-tus of paddy field was more serious than that of dry land. The comprehensive potential ecological risk in-dex was 36. 97,which showed potential ecological risk induced by these heavy metal elements to the soil system was low. The most significant contributor was identified to be As, the contribution rate of As was 39. 8% to the potential ecological risk. There were significantly positive relations between Cr content and Ni,Cu,As content, between Ni content and Cu content, between Cu content and As content, indicating there was combined pollution or same pollution source among the five metal elements.