北京市农业土壤重金属状态评价

以北京市土壤重金属背景值为标准.对比分析了农业土壤中Cr、Ni、Cu、Zn、As、Cd、Pb、Hg 8种重金属的含量及累积情况,并采用单因子污染指数法和综合污染指数法进行了土壤重金属污染评价.结果表明,北京市农业土壤存在着一定的Cr、Cu、Zn、As、Cd累积趋势,其含量的平均值分别为53.61、21.95、65.42、9.14、0.125 mg·kg-1,比相应的背景值高79.9%、17.4%、13-8%、28.9%、5.O%:Ni和Pb的累积则不明显.平均值比相应的背景值低7.9%、29.2%,分别为24.84和19.04 mg·kg-1;而Hg含量的平均值与背景值一致,为0.08mg·kg-1.从单因子评价结果来说,Cr污染指数在1.06-2.93之间,所有的样点都处于轻度或中度污染状态;As、Cu、Zn、Cd的污染指数相对较小,平均值分别为1.29、1.17、1.13、1.05,有50%以上的样点处于轻度污染状态;而Ni、Pb、Hg的污染指数均小于1,有60%以上的样点处于清洁或尚清洁状态,污染较轻.若从综合评价结果来说,综合污染指数处于0.96～2·16之间,平均值为1.45,几乎所有的土壤样点都属于轻度污染状态.

Status Assessment of Heavy Metals in Beijing Agricultural Soils

To evaluate the status of heavy metals in Beijing agricultural soil, 385 soil samples were collected and the concentrations of Cr, Ni, Cu, Zn, As, Cd, Pb and Hg were analyzed with the standardized method. Heavy metals were evaluated using the single-factor pollution index and the integrated pollution index based on the background level of heavy metals of Beijing. The results indicated that the mean concentration of heavy metals Cr, Ni, Cu, Zn, As, Cd, Pb and Hg were 53.61, 24.84, 21.95, 65.42, 9.14, 0.125, ...