复垦不同年限煤矸山土壤重金属污染状况评价

Evaluation on Heavy Metal Contents of Soil in Coal Waste Pile After Reclamation

为研究复垦年限对煤矸山土壤重金属的影响,以山西省霍州市曹村煤矿煤矸山复垦3a,5a,7a和9a农田为研究对象,对复垦地土壤重金属Hg,Cd,Pb,As和Ni的质量分数及其污染状况进行了分析。结果表明:(1)煤矸山复垦农田0—20cm和20—40cm土层土壤重金属质量分数有随复垦年限增加而增加的趋势,其中Pb,Cd表现最明显,而Hg的增加趋势主要出现在20—40cm土层;同时,煤矸山复垦农田土壤重金属质量分数均不同程度地高于当地普通农田,尤其在20—40cm土层表现更明显;(2)单因子污染指数表明,Hg和As在0—20cm和20—40cm土层污染程度随年限没有变化,分别为重度污染和轻微污染,Pb和Cd在0—20cm也没有变化,分别为轻微污染和轻度污染,但在20—40cm土层随年限增长达到轻度污染和中度污染;综合污染指数表明,复垦农田在0—20cm和20—40cm土层污染指数均表现为随复垦年限增加而增加的趋势,4种复垦年限农田均达到重度污染。研究结果有助于指导煤矸山植被恢复和复垦地的合理利用。

To evaluate the effects of reclamation years on heavy metals in coal waste pile soil,coal mine reclamation soils with reclamation years of 3years,5years,7years and 9years were examined in Cao village in Huozhou,Shanxi Province,the contents and pollution status of heavy metals Hg,Cd,Pb,As and Ni in reclamation soil were analyzed.The results showed that:(1)the contents of soil heavy metals in soil layers of 0—20cm and 20—40cm had the increasing trend over years,the contents of Pb and Cd increased most obviously,while the increasing trend of Hg content occurred in 20—40cm soil layer;meanwhile,the heavy metal contents in coal waste pile reclamation soil were higher than those in farmland soil in different degrees,especially in 20—40cm soil layer;(2)single factor pollution index showed that the contents of Hg and As in0—20cm and 20—40cm soil layers did not change with years,which were severe pollution and slight pollution,respectively;the contents of Pb and Cd in 0—20cm soil layers did not change,which were slight pollution and light pollution,respectively,but increased with years to light pollution and moderate pollution in the 20—40cm soil layer;the comprehensive pollution index showed that heavy metal pollution in reclaimed land in 0—20cm and 20—40cm soil layers presented the increasing trend with the reclamation years,and 4types of reclaimed lands all suffered the severe pollution.The research results are helpful to guide the rational use of coal waste pile reclamation land and vegetation restoration.