北京顺义区土壤重金属分布与环境质量评价

在北京顺义区采集了412份土壤表层样品,分析了其中7种重金属元素（Cu、Zn、Cr、Pb、Cd、As和Hg）的全量,采用单因子指数和内梅罗指数对土壤环境质量进行评价。结果表明,土样中As、Cd、Cr、Hg、Cu、Pb和Zn含量平均值分别为7.85、0.136、61.47、0.073、22.43、20.38mg.kg-1和69.75mg.kg-1,As、Cd、Cr、Cu和Zn含量平均值超过了北京地区环境背景值,但所有元素含量的平均值均未超出土壤环境质量一级标准。土壤中各重金属元素含量Shapiro-Wilk检验和相关性检验结果表明,研究区土壤中重金属Cr呈正态分布,Cd、Cr、Cu、Pb元素与As元素相关性显著。土壤各元素单因子污染指数排序为Zn〉Cr〉Cd〉Cu〉Pb〉As〉Hg,内梅罗综合污染指数平均值为0.745,达到了土壤环境质量评价分级标准Ⅱ级,污染等级为＂警戒线＂级;菜地、果园、荒地、林地、苗圃、设施农业用地和水浇地的土壤内梅罗指数分别为0.809、0.765、0.720、0.669、0.781、0.786和0.729,表现为菜地〉设施农业〉苗圃〉果园〉水浇地〉荒地〉林地。土壤环境质量总体安全,部分地区土壤重金属污染处于警戒水平。

Distribution and Environment Quality Evaluation of Heavy Metals in Soil in Shunyi of Beijing,China

Concentration of 7 heavy metals in 412 topsoil samples collected from Shunyi district of Beijing were determined,and the data were analyzed for the soil environment quality assessment by the single factor index and the Nemerow index.The results showed that average concentration of As,Cd,Cr,Hg,Cu,Pb and Zn were 7.85 mg·kg-1,0.136 mg·kg-1,61.47 mg·kg-1,0.073 mg·kg-1,22.43 mg·kg-1,20.38 mg·kg-1 and 69.75 mg·kg-1,respectively.Average concentration of As,Cd,Cr,Cu and Zn exceeded background value of Beijing area.At the same time,all heavy metals concentration were modestly below soil environmental quality standard classⅠ.A Shapiro-Wilk test was employed for the distribution test of soil heavy metals.It was found that Cr concentrations were in normal distribution.Relationship between soil heavy metal concentrations were analyzed.Cd,Cr,Cu and Pb were significantly correlated with As.The soil environment quality was assessed by single factor pollution index and Nemerow indices of heavy metals.The order of single factor index was Zn,Cr,Cd,Cu,Pb,As,Hg in decreasing.Average Nemerow index of soil was 0.745.This value was reached to the Ⅱ grade standard of soil environmental quality assessment classification.The Nemerow indices of soil in vegetable field,fruit field,bare land,woodland,tree nursery,greenhouse and irrigable land were 0.809,0.765,0.720,0.669,0.781,0.786 and 0.729,respectively.Most of the soil environment quality was at safe level and the pollution of heavy metal for some areas was at the alert level.