张掖绿洲农田土壤重金属污染潜在风险评价

摘要

以张掖市境内典型绿洲农业区内的部分农田为研究对象,分析了土壤中 Hg、As、Cu、Pb、Zn、Cd、Ni和Cr 8种重金属元素的含量特征,并采用地质累积指数法和潜在生态危害指数法对土壤重金属污染状况和潜在生态风险进行了评价。结果显示,研究区域农田土壤中8种重金属元素的平均含量均低于我国土壤环境质量标准二级标准。地质累积指数法评价结果表明,该区域内 Cd的地质累积指数在0~1之间,属于无污染-中度污染,其余7种元素地质累积指数均小于0,污染程度为无污染。潜在生态风险指数法的评价结果表明,研究区域的农田土壤重金属污染的潜在生态风险为轻度生态风险,但是 Cd元素的生态风险系数达到中度生态风险,应该引起充分关注。%Taking farmland soil in typical oasis agricultural area in Zhangye City as the research obj ect, this paper used geo-accumulation index and potential ecological risk index to analyze the content character-istics of eight heavy metal elements,Cr,Ni,Pb,As,Hg,Cd,Cu and Zn,in farmland soil,and evaluate their pollution in soil and potential ecological risks.Monitoring results showed that average contents of the eight heavy metal elements in soil of the study area were all lower than that in the secondary standard in China soil environmental quality standard.Evaluation results based on the geo-accumulation index indicated that geo-accumulation index of Cd in the study area was ranging from 0 to 1 ,namely non-pollution to medium pollution,and those of other elements were all below 0,namely no pollution at all.Evaluation results based on the potential ecological risk index indicated that soil heavy metal pollution could cause slight ecological risks in the study area,but ecological risk coefficient of Cd reached the medium degree,to which adequate attention should be paid.