甘肃省平凉市土壤重金属潜在生态风险评价

为了揭示农田土壤中重金属元素潜在的污染特征，2004—2011年在甘肃省平凉市农田抽取黑垆土、黄绵土等6个土类147个土壤样点，检测As、Hg、Pb、Cr、Cd 5种重金属含量，并采用Hakanson潜在生态风险指数，研究了甘肃省平凉市农田土壤重金属污染程度及潜在的生态危害性。结果表明，As、Hg、Pb、Cr、Cd平均含量分别为9.96、0.038、32.16、65.98、0.119 mg/kg，变异系数分别为30.72%、93.94%、47.72%、28.36%、60.84%，潜在生态风险系数分别在3.09~18.04、3.85~323.88、1.19~30.90、0.46～3.22、3.96~100.85之间，6个土类农田风险指数在29.21~356.69之间。土壤重金属Hg、Cd分布不均匀，As、Pb、Cr分布相对均匀，农田土壤重金属有潜在生态风险，Hg、Cd构成的风险较大。

Potentail Ecological Risk Assessment of Heavy Metals in Soil in Pingliang City, Gansu Province

In order to research the potential pollution characteristics of heavy metals in farmland, from 2004 to 2011, the author sampled heilu soil, loessial soil, and so on 6 soil types, including 147 soil samples, detected 5 kinds of heavy metal content, which were As, Hg, Pb, Cr, Cd, in farmland of Pingliang City of Gansu Province, and the potential ecological risk and pollution degree of the heavy metals in farmland were evaluated using Hakanson ecological risk index. The results showed that: the average content of As, Hg, Pb, Cr, Cd were 9.96, 0.038, 32.16, 65.98 and 0.119 mg/kg, the coefficient of variation were 30.72%, 93.94%, 47.72%, 28.36% and 60.84%, the potential ecological risk coefficient were 3.09-18.04, 3.85-323.88, 1.19-30.90, 0.46-3.22, 3.96-100.85, 6 soil farmland risk indexes were 29.21-356.69. The distribution of Hg, Cd was not uniform, while As, Pb, Cr was relatively uniform, so the soil heavy metal in farmland had potential ecological risk, Hg, Cd had bigger risk.