乌兰察布市农业用地土壤重金属污染生态风险评估

Ecological Risk Assessment of Heavy Metal Pollution in Agricultural Land Soil in Wulanchabu City

为系统研究乌兰察布市耕地土壤重金属污染状况,采集全市11各旗(县、区、市)共计1405个农业用地土壤样品(0~20 cm)进行Cr、Cd、Pb、Hg、As共5种重金属含量分析,利用地积累指数法和潜在生态危害风险指数法评估土壤污染状况。结果表明:土壤中Cr、Cd、Pb、Hg、As含量的平均值均低于农用地土壤污染风险筛选值;5种重金属地积累指数(I_(geo))总和为0或1,土壤无污染或轻度污染;潜在生态危害风险指数(RI)中,察右中旗、凉城县及兴和县潜在轻微生态危害污染程度占比均高于90%,土壤生态危害较轻,商都县和丰镇市潜在轻微生态危害污染程度占比分别为35.5%和34.9%,中等、强、很强潜在生态危害级别占比较高,土壤生态危害风险较高。全市RI平均值为140.85,土壤属于轻微生态危害风险。综上,全市各地区农业土壤重金属污染危害较轻,土壤重金属生态风险较低。

In order to systematically study the heavy metal pollution of cultivated soil in Wulanchabu City,a total of 1405 agricultural soil samples(0~20 cm)from 11 countries of the city were collected to analyze the heavy metal contents of Cr,Cd,Pb,Hg,and As.The soil pollution status was evaluated by geo-accumulation index method and potential ecological hazard risk index method.The results show that the average content of Cr,Cd,Pb,Hg and As in the soil is lower than the soil pollution risk screening value of agricultural land.The sum of the geo-accumulation index(I_(geo))of 5 heavy metals is 0 or 1,and the soil is not polluted or lightly polluted.In the potential ecological hazard risk index(RI),the proportion of potential minor ecological hazards in Chayouzhongqi,Liangcheng County and Xinghe County are all higher than 90%,and the soil ecological hazard is relatively light.Pollution levels of potential minor ecological hazards in Shangdu County and Fengzhen City accounted for 35.5% and 34.9% respectively.Medium,strong,and very strong potential ecological hazards accounted for relatively high levels,and the risk of soil ecological hazards was relatively high.The average RI in the city is 140.85,and the soil is at risk of minor ecological hazards.In summary,the pollution of heavy metals in agricultural soils in all regions of the city is less harmful,and the ecological risks of heavy metals in soils are low.