基于GIS的县域土壤重金属生态风险评价

Potential ecological risk assessment of heavy metal in soils based on GIS

为研究经济快速发展区农田土壤中重金属的含量及污染状况,本文以浙江省慈溪市为研究对象,研究土壤中铜、汞、镉、铅、砷、铬、锌七种重金属含量特征,并采用潜在生态危害指数法对其进行评价,并绘制生态风险危害指数分级图。结果表明:土壤中除汞元素含量较高外,其他各元素含量仅稍高于当地土壤背景值。七种元素的单因子污染指数Cfi值均属于中等的污染参数,综合污染指数Cd上限值已处于高污染指数的范围,但平均值为属于中等污染水平。从潜在生态风险评价结果来看,七种元素的单项潜在生态风险参数Eri的值也只有汞达到了强生态危害,七种元素综合潜在生态危害指数RI刚刚达到中等生态危害水平,说明该区农田土壤尚处于较低的生态风险状态。生态危害指数插值结果表明,慈溪市重金属元素的高风险区分布在中南部人类活动较为活跃、城乡工业较发达的区域,在今后的土地利用中,应高度重视人类活动对土壤重金属污染的影响。

A case study is performed to research the character of heavy metal（Cu, Hg, Cd, Pb, As, Cr, Zn） pollution in sods in Cixi city of zhejiang province. The potential ecological risk assessment has been done and the pollution classified map has also been drawn based on GIS. The results show that the heavy metal pollution is not serious in agricultural soils, the heavy metal pollution index （Cf^i） is in the middle pollution parameters. The maximal integrated pollution index（Cd） of seven heavy metals is in the higher range of pollution parmeters, but its mean just slightly exceed the middle pollution parameters. The potential ecological risk index（ Er^i） iS in lower ecological risk except that Hg is higher. The integrated potential ecological hazard index R/is 157. 1, just slightly exceed the middle ecological risks. It suggests that in agricultural soils of this region, the ecological risk of the heavy metal pollution is in relatively lower standards. The classified map of heavy metal pollution indicates that the high risk area located in middle and south parts of Cixi county where human being activities are stronger and industry is developed, so the influence of human being＇ s activity on heavy metal pollution in soil should be paid more attention in land use planning in the future.