煤矸石重金属释放活性及其污染土壤的生态风险评价

Characteristics of Heavy Metals Release from Coal Waste and Potential Ecological Risk Assessment of Contaminated Soil Around Coal Waste Piles

通过野外采样与室内实验分析煤矸石重金属的释放活性,并利用潜在生态风险评价法分析煤矸石山周边土壤污染及其潜在生态风险特征。结果表明,实验用煤矸石中重金属主要以残渣态存在,Cu、Zn、Pb、Cr和Cd的残渣态分别占其总量的56.86%,53.27%,72.01%,68.61%和75.93%,不易发生释放迁移,但少量酸溶态和氧化物结合态重金属易被淋溶后在矸石山周围土壤中累积并造成重金属污染。煤矸石山周边土壤重金属含量随着距离的增加呈现减少趋势,表明周边土壤受到煤矸石重金属污染,并且在土壤表层重金属含量最高,加大了重金属进入食物链危害人体健康的风险。通过潜在生态风险评价研究,采样区属于重金属Cd和Pb风险突出区,煤矸石距离5～10 m处潜在生态风险指数为272.34和164.34,属于中等潜在生态风险,其他各点潜在生态风险指数范围为94.62～141.79,属于轻微生态风险。

Characteristics of heavy metals release from coal waste and potential ecological risk assessment of contaminated soil around coal waste piles were studied.The results showed that：（1）Residual fraction was the main fraction of heavy metal in coal waste,such as Cu,Zn,Pb,Cr and Cd accounted for 56.86%,53.27%,72.01%,68.61% and 75.93%,which could not easily release from coal waste,but few acid soluble fraction and oxidizable fraction could release and contaminate the soil;（2）Soil heavy metal contents decreased with the distance from coal waste piles increase,which showed the soil was contaminated,and heavy metal contents of top layer were highest than other soil layer,which could cause the heavy metal into crop and endanger human body.Potential ecological risk assessment was used to evaluate the contamination situation of various heavy metals,and Cd,Pb were the main ecological risk factor.The area within 5 m and 10 m distance from coal waste piles belongs to mild ecological risk,with ecological risk index of 272.34 and 164.34,and other sampling area belong to slight ecological risk,with ecological risk index of 94.62 to 141.79.