基于土壤酶总体活性评价铅锌尾矿砂坍塌区土壤重金属污染

为探讨利用土壤酶总体活性表征铅锌尾矿砂造成的土壤重金属污染程度，本文对阳朔思的村水稻田、柑橘园和玉米地土壤中铅、锌、铜、镉的有效态质量分数以及参与土壤碳、氮、磷循环的纤维素酶、蔗糖酶、脲酶、蛋白酶和酸性磷酸酶活性进行了测定。结果表明：供试土壤中镉、铅、锌的有效态质量分数（分别为2.39-4.42、173.71-221.66、140.11-244.10 mg＆#183; kg-1）均高于其全量在GB15618-1995《土壤环境质量标准》中的Ⅱ级标准，分别是Ⅱ级标准值的9.56-14.73、2.18-2.77、0.77-1.22倍，并且土壤中有效态镉带来的潜在生态风险最高。为进一步评价铅锌尾矿砂给不同土地利用类型土壤带来的生态环境风险，在对土壤重金属有效态质量分数进行归一化处理后，发现土壤重金属污染程度从高到低依次为水稻田、柑橘园、玉米地。由于土壤中的重金属复合污染物铅、锌、铜、镉对土壤酶活性的影响既有抑制作用，又有激活作用，因此不同土地利用类型下的单一土壤酶活性状态与土壤所遭受的重金属污染程度呈现出不一致的变化规律。而以土壤总体酶活性指数对各样本进行分类，发现水稻田、柑橘园、玉米地的土壤总体酶活性指数分别为4.345、5.153、5.502，其结果与以重金属有效态归一化处理之后获得的综合污染指数划分结果呈反比，从而说明利用土壤总体酶活性指数来表征不同土地利用类型下的土壤重金属综合污染状况是切实有效的。

Assessment on Heavy Metals in the Pb-Zn Mine Tailing Dam Collapse Area Based on Total Enzyme Activity Index

To understand the influence from the compound pollution of Pb, Zn, Cu and Cd on soil enzyme activities （soil invertase, cellulose, urease, protease and acid phosphatase） in the Pb-Zn tailing dam collapse area, soil samples from different land-use types （paddy field, orange field and corn field） were collected in Sidi village, Guangxi Zhuang Autonomous Region, SW China. Based on the analysis of soil available heavy metals of Pb, Zn, Cu, Cd, the results show that in the top soil, the contents from soil available heavy metals of Cd, Pb and Zn are 2.39-4.42 mg＆#183; kg-1, 173.71-221.66 mg＆#183; kg-1 and 140.11-244.10 mg＆#183; kg-1, which are 9.56-14.73, 2.18-2.77 and 0.77-1.22 times higher than those stipulated in the State Environmental Quality Standard for Soils （GB 15618-1995）, respectively. Moreover, the above extraction experimental results prove the fact that Cd is the main ecology factor in this area. According to the normalized overall soil available heavy metals, the potential environmental risk caused by the compound pollution of Pb, Zn, Cu and Cd on soil indicated that the potential ecology risk of surface soil from Pb-Zn tailing sand was paddy field 〉orange field〉corn field. Due to the complex relationship between the compound pollution of Pb, Zn, Cu, Cd and the soil enzyme activities, signal enzyme activity index can not reflect the pollution condition. When the total enzyme activity index is calculated, it is found the total enzyme activity indices in corn field, orange field and paddy field are 4.345, 5.153 and 5.502, respectively and there is a negative sequence between the total enzyme activity indices and the heavy metal combined pollution indices in the tested soils. Therefore, the research proves that the simple total enzyme activity index can be as a biochemical indicator in the heavy metal pollution soil.