关中灌区农业土壤重金属污染调查与评价

通过对关中宝鸡峡灌区、交口灌区、洛惠东灌区农业土壤样品的采集、监测,依据关中土重金属元素背景值和国家《土壤环境质量标准》(GB15618-1995)二级标准作为评价标准,重点分析评价了对土壤环境及人体危害较大的Cd、As、Cr、Pb等重金属元素的累积程度和污染程度。结果表明:以关中土重金属元素背景值为评价标准,关中灌区土重金属综合累积程度依次为交口灌区、宝鸡峡灌区、洛惠东灌区,土壤重金属累积程度具有PbAsCrCd的特征;关中灌区农业土壤重金属Pb累积程度普遍较高,主要是由于长期污水灌溉所致。以国家土壤环境质量二级标准为评价指标,关中灌区土重金属污染程度依次为宝鸡峡灌区、洛惠东灌区、交口灌区,土壤重金属污染程度具有AsCrCdPb的特征;关中灌区农业土壤重金属综合污染指数P均小于0.7,土壤样品单项污染指数Pi均小于0.7。因而,关中灌区农业土壤环境中的重金属元素含量现状适宜于无公害农产品和果品基地建设的要求。

Investigation and Assessment on Heavy Metals Pollution of Agricultural Soil in Guanzhong Irrigation District

The monitored soil samples were collected from Baoji gorge irrigated area,Jiaokou irrigated area and Eastern Luohui irrigated area in Guanzhong District.According to the background concentrations of heavy metals in Guanzhong Loutu soil and the Environment Quality Standard for Soil(GB15618-1995誖),this thesis evaluated the accumulation degree and the pollution status of heavy metals(Cd,As,Cr and Pb) that could seriously endanger soil environment and human health by using single-factor index and synthetic pollution index methods.The results indicate that the accumulation degree of soil heavy metals is in the order of Jiaokou irrigated area,Baoji gorge irrigated area and Eastern Luohui irrigated area in Guanzhong Irrigation District,the accumulation degree of soil heavy metals has the feature of Pb > As > Cr > Cd by the background concentrations of heavy metals in Guanzhong Loutu soil;The accumulation degrees of Pb in agricultural soil are in a higher condition in Guanzhong Irrigation District,which was mainly caused by the long-term sewage irrigation.The pollution degree of soil heavy metals is in the order of Baoji gorge irrigated area,Eastern Luohui irrigated area and Jiaokou irrigated area in Guanzhong Irrigation District,the contaminated degree of soil heavy metals has the feature of As > Cr > Cd > Pb;The synthetic pollution indices and the single-factor indices of soil heavy metals of all soil samples are less than 0.7,so the heavy metals contents in soil environment is in a good condition in Guanzhong Irrigation District,and it is suitable for establishing the nuisance free agricultural products and fruits productive base by the Environment Quality Standard for Soil(GB15618-1995).