为掌握银川市城市绿地土壤重金属的空间分布特征及其生态风险状况,分析测定了Cr,Ni,Cu,Zn,As,Hg,Cd和Pb含量,利用单因子、内梅罗污染指数法和Hakanson潜在生态风险指数法对不同绿地土壤重金属的污染程度和潜在生态风险进行了评价。结果 表明:银川市绿地土壤中除Cr外,其他7种重金属元素的平均含量均超过了银川市土壤背景值,其中Hg,Cd,Pb超标严重,重金属在道路绿地和生产绿地中富集现象最明显。绿地土壤各重金属元素的空间分布特征较为一致,高值区主要集中在中部、东部以及东北部,主要受工业生产、交通、商业、养殖场等人类活动的影响。污染评价表明,Hg属于中度污染,其他重金属元素均属于轻微污染或警戒水平,5种绿地类型土壤重金属均属于轻度污染。研究区5种绿地土壤重金属综合潜在生态风险指数大小排序为:道路绿地>生产绿地>公园绿地>居住绿地>防护绿地,其中道路绿地、生产绿地和公园绿地均处于中等生态风险,居住绿地和防护绿地处于轻微生态风险。8种重金属元素单项潜在生态风险指数(Eir)平均值大小顺序为:Hg>Cd>As>Pb>Cu>Ni>Cr>Zn,Hg为强生态风险级别。银川市绿地土壤总体处于中等生态风险,Hg是最主要的生态风险元素,应引起重视。
In order to understand the spatial distribution characteristics and ecological risk of heavy metals in green space of Yinchuan City, the contents of Cr, Ni, Cu, Zn, As, Hg, Cd and Pb were determined. The pollution levels and potential ecological risks of soil heavy metals in different types of green space were evaluated by single factor, Nemero pollution index and Hakanson potential ecological risk index methods. The results show that except for Cr, the average contents of the other seven heavy metal elements exceeded the background values of Yinchuan City, and the Hg, Cd, Pb exceeded the standard seriously; heavy metals are mainly accumulated in road green space and production green space; the spatial distribution characteristics of heavy metal elements in green space are relatively consistent, and areas with the high values of heavy metal contents mainly concentrate in the central, eastern and northeastern parts, which are mainly affected by human activities such as industrial production, transportation, commerce, farming, and so on. Pollution evaluation shows that Hg is moderate pollution, other heavy metal elements are slight pollution or warning level, and all the green spaces belong to slight pollution grade. The comprehensive potential ecological risk indices of heavy metals in five types of green space decrease in the order: road green space>production green space>park green space>residential green space>protective green space, among which road green space, production green space and park green space are at moderate ecological risk, residential green space and protective green space are at slight ecological risk. The average of the individual potential ecological risk index(Eir)of each of the eight heavy metals decreases in the order: Hg>Cd>As>Pb>Cu>Ni>Cr>Zn, Hg has reached the strong ecological risk level. All in all, the green space soil in Yinchuan City is at moderate ecological risk, Hg is the main element of potential ecological risk, which should be paid attention to.
