兰坪金顶铅锌矿区土壤重金属Zn、Cd分布特征研究

Research on the Distribution Characteristics of Zn,Cd in the Soil of Jinding Pb—Zn Deposit,Lanping County

通过连续提取法测定兰坪金顶铅锌区土壤中Zn、Cd的形态含量,笔者等分析了污染物的分布、化学形态的变化。结果表明,金顶矿区土壤中Zn、Cd总量大范围超标,Zn的水溶态含量为n·100μg/g,离子交换态为n·10μg/g,残渣态、活性铁锰态、碳酸盐态和有机结合态含量为n·102μg/g,Cd的水溶态含量为n·10-2μg/g,其他各态基本在同一数量级为n·100μg/g,部分地区Zn离子交换态含量超过国家土壤环境质量标准(Ⅲ级)中总量标准1倍以上,而Cd离子交换态含量平均是Ⅲ级总量标准的5倍,Cd污染要更加严重。污染及形态分布受矿体展布、地形、矿业活动、地表径流等的影响。Zn、Cd的环境有效态(水溶态、离子交换态与碳酸盐态之和)含量比较高,对兰坪矿区及沘江流域具有潜在的危害。

In the article, the speciations of Zn and Cd in the soil of the Jinding Pb--Zn deposit are analyzed by sequential extraction procedure, the distribution characteristics and the speciation variation of heavy metals are studied. Results show that most of the soil in Jinding area is polluted by Zn and Cd. The average content levels of Zn for each phase are： water-soluble fraction is n ·10^0μg/g, exchangeable fraction is n ·10 μg/g, residual, Fe, Mn oxide, carbonate and organics are n·10^2μg/g. The average content levels of Cd are. water-soluble fraction is n ·10^2μg/g, the other are n ·10^0μg/g. In some points, according to the soil environmental quality standars（3rd Class）,the content of exchangeable Zn is ltimes higher, while the average content of exchangeable Cd is 5 times higher. Cd pollution is much more severe than Zn. Distributions of Zn and Cd are influenced by the distributions of the deposit, the terrain, the mining activity, and the distribution of the rivers. For the available fractions of the heavy metals are higher in Lanping area, there will be great danger to Lanping area and Bijiang river domain.