铅锌矿渣中汞的渗滤特性及其在稻田土壤中的迁移转化特征

The Leaching Features of Mercury from Lead-zinc Mine Tailings and the Subsequent Migration and Transformation Characteristics in Paddy Soil

关于雨水淋溶作用下铅锌矿渣中汞的渗滤特性及其在稻田土壤中的迁移转化特征并不清楚,本研究利用铅锌矿渣和未受污染的稻田土壤构建微宇宙环境系统,探究其相关特性/征。结果表明,渗滤液中汞的浓度随降雨量的增加而逐渐上升,不同降雨量条件下渗滤液中汞的浓度存在显著差异(p<0.05);一级动力学方程和DoseResp模型均能较好地拟合汞的渗滤过程;在矿渣影响下,不同深度稻田土壤中汞的浓度均显著增加,且随时间的推移呈逐渐升高的规律,0~8、8~15和15~20 cm土壤中汞的垂向迁移速率分别为8.8×10^(-4)~2.2×10^(-3)、2.3×10^(-4)~4.1×10^(-4)和3.0×10^(-7)~8.1×10^(-5) mg/(kg·cm·d);在矿渣影响下,土壤中残渣态汞的比例下降,其余形态汞的比例均出现不同程度上升,说明在铅锌矿渣影响下稻田土壤汞的生态风险升高。研究结果可为铅锌矿区生态环境保护提供研究基础。

The mining and smelting processes of lead-zinc mine can cause serious mercury(Hg)pollution in the surrounding soils with extremely high risk.The leaching features of Hg from lead-zinc mine tailings and the subsequent migration and transformation characteristics in paddy soil are unclear at present.The lead-zinc mine tailings and unpolluted paddy soil were thus used to construct a micro-ecological environment for identifying the leaching features of mercury from lead-zinc mine tailings and the subsequent migration and transformation characteristics in paddy soil.The results showed that the concentrations of Hg in leachate increased with the increasing of rainfall.The concentrations of Hg in leachate under different rainfall varied significantly(p<0.05).The leaching results of Hg form lead-zinc mine tailings could be well fitted by first-order dynamic equation as well as DoseRep model.Under the impact of lead-zinc mine tailings,the contents of Hg in paddy soil at each depth increased significantly and the contents also increased with simulated time.The average vertical migration rates in the paddy soil of 0-8 cm,8-15 cm,and 15-20 cm within 120 days were calculated to be 8.8×10^(-4)-2.2×10^(-3),2.3×10^(-4)-4.1×10^(-4),and 3.0×10^(-7)-8.1×10^(-5) mg/(kg·cm·d),respectively.The residual fraction decreased and the other fractions increased at some extent,suggesting that the ecological risk of Hg in paddy soil increased under the impact of lead-zinc mine tailings.The results can provide research basis for protecting the ecological environment around lead-zinc mining areas.