德兴铜矿大坞河流域土壤中Cd的环境地球化学特征及意义

摘要

采用连续提取法对德兴铜矿大坞河流域的土壤样品中Cd元素的形态进行分析,并基于缓变型地球化学灾害模型,对大坞河流域土壤中Cd的环境地球化学特征进行研究.结果显示,大坞河上游的祝家村附近和中游的德铜医院附近的土壤中Cd元素活动性污染总浓度(total concentration of active specie of Cd,以下记为TCAScd)随着污染物的可释放总量(total releseable content of the pollutant of Cd,以下记为TRCPcd)增加而增加,二者之间呈线性关系.虽然大坞河上一中游的样品中TRCPcd范围均在国家三级土壤标准之下,但随着该地区土壤中Cd元素的不断输入,这种情况下所造成的污染相对于缓变型地球化学灾害造成的污染,应当更加引起重视.在大坞河下游的下沽口村附近土壤中,Cd的各形态数据特征符合缓变型地球化学灾害特征,且有TRCPcd向TCASCd释放转化的趋势.Cd元素的缓变型地球化学灾害模型为y=1.12167E-04x3-6.25584E-02x2+1.15298E+ 01x-6.07452E+ 02.爆发临界点为TRCPcd=185.90ng/g,有约36％的样品超过爆发临界点,具有爆发缓变型地球化学灾害的可能性.这种认识对大坞河流域土壤中Cd元素污染的预警和对生态环境的改善具有重要意义.%The speciations of Cd element are analyzed and the environmental geochemical characteristics of Cd are studied by using sequential extraction procedure and the mathematical model of delayed geochemical hazard (DGH) in the soil of the Dawu River of the Dexing Copper orefield,Jiangxi Province.The results show,total concentration of active specie of Cd(TCAScd) increased when total releasable content of the pollutant of Cd(TRCPcd) increased in the soil of Dawu upper river where is closed to Zhujiacun and Dawu middle river where is closed to hospital of Dexing copper field,and there is a linear relationship between them.Although samples in the soil of the Dawu upper river and middle river are under the national three level soil standard,the pollution caused by this kind of circumstance which should get more attention than the pollution caused by delay geochemical hazard along with Cd element is constantly input to soil of this region.The data characteristics of soil in the Dawu lower river where is closed to Xiagukoucun accord to DGH characteristics.Cd element in the soil of the Dawu lower river tends to shift from release of TRCPcd to that of TCAScd,and its DGH model was y =1.12167E-04x3-6.25584E-02x2 +1.15298E +01x-6.07452E +02,The calculation for outbreak of critical point TRCPcd =185.90 ng/g,about 36％ of samples the DGH of Cd element is very likely to break out in the soil sampling profile of the Dawu lower river which is closed to Xiagukoucun; meanwhile,this viewpoint is of great significance to early-warning of soil Cd pollution and improvement of ecological environment in the study area.