东阳市农田土壤和农作物重金属污染评价及相关性分析

Heavy Metal Pollution Evaluation and Correlation Analysis of Farmland Soil and Crops in Dongyang City

以东阳市农田区域为研究对象,重点对农业两区集中连片的基本农田保护区及土壤地球化学调查重金属异常区进行农产品安全性调查。采用点对点协同采样的方法对东阳市农田土壤和农作物进行采集,测定了As、Cd、Cr、Cu、Hg、Ni、Pb和Zn元素8种重金属含量。使用地累积指数和潜在生态风险指数对土壤重金属污染进行评价。结果表明:研究区存在Cd和Pb污染,相较于农用地风险筛选值,超标率分别为11.67%和5.0%;农作物存在Cd、As污染,相较于食品污染物限量,70件稻谷重金属As、Cd含量超标,超标率为25.71%、10.0%;14件芋头中重金属Cd超标,超标率为42.86%。土壤污染评价表明,土壤重金属Cd等存在强生态风险,其余重金属存在轻微生态风险可接受范围。相关性分析,土壤中As、Cr对稻谷的吸收具有拮抗作用,而土壤Cu、Ni对稻谷吸收Cd具有促进作用;土壤As、Ni对芋头Cu、Cr、Pb、Zn吸收具有拮抗作用,土壤As、Ni对芋头Cd吸收具有促进作用。

Taking the farmland area of Dongyang as the research object,the safety of agricultural products was investigated mainly in the basic farmland protection area and the abnormal heavy metal area of soil geochemical investigation.The contents of As,Cd,Cr,Cu,Hg,Ni,Pb and Zn in the soil and crops of Dongyang were determined by point-to-point collaborative sampling method.Soil heavy metal pollution was evaluated by soil accumulation index and potential ecological risk index.The results showed that Cd and Pb pollution existed in the study area,compared with the risk screening value of agricultural land,the over-standard rates were 11.67% and 5.0%.There were Cd and As pollution in crops,compared with the limit of food pollutants,the content of heavy metals As and Cd in 70 pieces of rice samples exceeded the standard,and the overstandard rates were 25.71%and 10.0%;The heavy metal Cd in 14 pieces of taro samples exceeded the standard,and the over-standard rate was 42.86%.Soil pollution evaluation showed that heavy metals such as Cd had strong ecological risk,while other heavy metals had slight ecological risk acceptable range.Correlation analysis showed that As and Cr in soil had antagonistic effects on the absorption of rice,while Cu and Ni in soil had promoting effects on the absorption of Cd in rice.As and Ni in soil had antagonistic effects on the absorption of Cu,Cr,Pb and Zn in taro,while As and Ni in soil had promoting effects on the absorption of Cd in taro.