张掖市甘州区北部土壤重金属污染特征及生态风险评价

Pollution characteristics and ecological risk assessment of soil heavy metals in northern Ganzhou district, Zhangye city

为研究张掖市甘州区北部土壤重金属空间分布特征及污染状况,采集47个表层和19个深层土壤样品。采用单因子污染指数法、内梅罗综合污染指数法及潜在生态风险指数法评价土壤重金属(Mn、Zn、Hg、Pb、Cr和Ni)污染程度。结果表明:研究区土壤中Mn、Zn、Hg、Pb、Cr和Ni的平均含量分别是当地土壤背景值的0.91、0.98、4.79、1.06、1.42和0.97倍,均未超出国家二级标准值;6种重金属均主要处于轻度污染等级及以下,其中Hg还存在一定程度的重度污染;研究区土壤总体受到一定程度的重金属污染;Hg部分处于强生态风险水平,其他5种重金属均处于轻微生态风险水平;研究区土壤重金属总体上主要处于轻微生态风险水平,Hg是主要的风险因子;重金属污染较严重和潜在生态风险较强的区域均主要集中城镇及周边地区。

In order to study the spatial distribution characteristics and pollution status of heavy metals in soil of northern Ganzhou District,Zhangye City,47 surface and 19 deep soil samples were collected.The single factor pollution index,Nemerow comprehensive pollution index and potential ecological risk index were used to evaluate the soil heavy metals(Mn,Zn,Hg,Pb,Cr and Ni)pollution degrees.The results show that the average contents of Mn,Zn,Hg,Pb,Cr and Ni in the soil of the study area are 0.91,0.98,4.79,1.06,1.42 and 0.97 times of the background values of the local soil,respectively,they do not exceed the national secondary standard values.The six heavy metals are mainly at the light pollution level and below,among which Hg still has a certain degree of heavy pollution.The soils in the study area are polluted by heavy metals to some certain extent.Hg is at a strong ecological risk level,while the other five heavy metals are at a slight ecological risk level.The soil heavy metals in the study area are mainly at a slight ecological risk level,and Hg is the main risk factor.The areas with serious heavy metal pollution and high potential ecological risk are mainly concentrated in towns and surrounding areas.