煤矸山复垦土壤重金属污染的生态风险评价

摘要

[目的]土壤重金属污染是煤矸山复垦地植被恢复的重要障碍因素.因此,查明煤矸山复垦土壤重金属污染程度对指导煤矸山植被复垦具有重要作用.[方法]以山西省长治王庄煤矸山复垦6年的林地(SL)和草地(GL)为研究对象,分析了2种植被类型煤矸山土壤重金属Hg、As、Pb、Cd和Ni污染的生态风险.[结果]①从2种复垦地重金属含量的差异来看,在20～40 cm土层,复垦林地(SL)和复垦草地(GL)Pb、Hg、As和Ni不同程度偏高,其中Pb最明显,但在0～20 cm土层,2种复垦地土壤重金属含量低于CK样地.②从土壤重金属潜在生态风险单个污染要素看,复垦煤矸山土壤中Hg和Cd是主要的污染元素,其中Hg属于极强的生态危害,Cd属于中等生态危害;在0～20 cm土层,GL样地和SL样地污染状况差异较小,但在20～40 cm土层污染程度差异较大;从土壤重金属潜在生态风险综合指数来看,0～20 cm土层危害程度表现为GL＞ SL;20～40 cm土层为SL＞ GL.[结论]可见,2种复垦样地20 ～40 cm土层重金属含量高于普通灌草林地,并且Hg和Cd是复垦样地中主要的污染元素;2种复垦样地重金属综合污染程度在0～20 cm土层表现为复垦草地高于复垦林地,但在20～40 cm土层正好相反.%[Objective] The heavy metal pollution is the key limiting to vegetation reclamation in reconstruction coal waste pile.Therefore,it is very important to identify the pollution status in reclaimed soil of the coal waste pile.[Method]Taken the coal waste pile reclamation of shrubland (SL) and grassland (GL) of 6 years after reclamation in Wang village Changzhi city Shanxi province as a case,the pollution ecological risk of Hg,As,Pb,Cd and Ni in the two kinds of soil were analyzed.[Result] (i) From the difference of heavy metal content in the 2 sampling plots,in 20-40 cm soil layer,the Pb,Hg,As and Ni in SL and GL were higher than that in CK,and Pb was the most obvious,but in 0-20 cm soil layer,the heavy metal content was lower than that in CK.(ii) From the point of view of soil heavy metal potential ecological risk of individual pollution elements,Hg and Cd in reclamation soil were the main pollution elements,Hg was very strong ecological risk,and Cd was medium ecological risk;In 0-20 cm soil layer,the difference of pollution risk in the 2 sampling plots was small,but it was obvious in 20-40 cm soil layer.The results of comprehensive pollution index indicated that,the pollution degree was GL ＞ SL in 0-20 cm,but it was SL ＞ GL in 20-40 cm soil layer.[Conclusion] The soil heavy metal contents in SL and GL was higher than CK in 20-40 cm soil layer,and Hg and Cd were the main pollution elements in 2 sampling plots;The comprehensive heavy metals pollution index was higher in GL than that in SL in 0-20 cm soil layer,but it was opposite in 20-40 cm soil layer.