冷水江市锑矿区土壤重金属污染时空演变初探

Preliminary study on spatial and temporal evolution of heavy metals pollution in the soil of antimony mining area in Lengshuijiang City

通过选取湖南省冷水江市锑矿区土壤作为研究对象,分析锑矿区土壤在不同深度土层(0~20 cm、20~60 cm)的4种重金属(As、Cd、Pb、Sb)在前后6年之间含量变化特征,基于湖南省土壤背景值和全国土壤背景值为评价标准进行不同时空土壤重金属污染评价。结果表明:随着时空演变,土壤pH出现不同幅度的增加,使得植物更易存活;As含量除在兔子岭和雷公岭土壤深度20~60 cm土层出现小幅度的减少外,其余都呈现不同程度的增加;Cd含量除在兔子岭土壤深度20~60 cm土层出现大幅度减少外,其余都呈现不同程度的增加;Pb含量均呈现不同程度的减少;Sb含量均呈现不同程度的增加。表明冷水江市锑矿区土壤存在明显的Sb、As、Cd污染,主要来源于采矿过程中的粉尘沉降。冷水江市锑矿区土壤2015年综合污染指数为10.99,2021年综合污染指数为135.48,均大于P com>3.0,为重度污染。

In the present work,the soil of antimony mining area of Lengshuijiang City was selected as the research object,and the content characteristics of four heavy metals(As,Cd,Pb,Sb)at different depths(0~20 cm,20~60 cm)in 6 years were analyzed.The soil background values of Hunan Province and the national soil background values were used as the evaluation criteria to evaluate soil heavy metal pollution in different time and space.The results showed that the pH of soil was increased in different amplitudes with spatio and temporal evolution,which made the soil in mining area more survivable for plants.As content increased to varying degrees expect for a small decrease at 20~60 cm in Tuzi ridge and the Leigong ridge.Cd content increased to varying degrees except for a large decrease at 20~60 cm in Tuzi ridge.Pb content was decreased to varying degrees;while Sb content was increased to varying degrees.The obvious pollution of Sb,As and Cd were identified in the soil of antimony mine of Lengshuijiang City,which mainly comes from dust deposition in the mining process.The comprehensive pollution indexes of the soil in the antimony mining area of Lengshuijiang City in 2015 and 2021 were 10.99 and 135.48,which were higher than 3.0(P com),indicating the severe pollution.