锰矿农作物恢复区土壤重金属污染模糊综合评价

Fuzzy Synthetic Assessment of Heavy Metal Contamination in Crop-reclaimed Mn Minelands

对广西八一、荔浦、平乐、全州、板苏和下雷6个锰矿食用农作物恢复区土壤重金属进行含量测定，结果表明，土壤各元素含量为：Pb41．63～348．31mg·kg^-1、Cr48．12～287．29mg·kg^-1、Zn47．38～269．92mg·kg^-1、Cu12．71～138．03mg·kg^-1、Cd0．73-46．50mg·kg^-1、Mn676．7～41996．4mg·kg^-1。Mn和Cd最高含量分别为广西土壤背景值的243倍和754倍。采用模糊综合评价法对土壤重金属进行评价：从单因素决定模型看，恢复区土壤对环境质量三级标准的平均隶属度为0．4340．981；从加权平均模型看，土壤对三级标准的隶属度为0．366～0．974。除下雷矿区外，其余5个锰矿恢复区土壤对三级标准的平均隶属度〉0．7，各采样区重污染率为100％；其中，Cd含量对三级标准隶属度〉0．8，Cd重污染率达100oA，是恢复区土壤的首要污染因子。因此，在锰矿废弃地生态恢复初期，应避免采用种植食用农作物恢复模式。

Extensive soil sampling of the crop-reclaimed Mn mine wastelands was conducted in the six typical manganese minelands （Bayi,Lipu,Pingle,Quanzhou,Bansu and Xialei） in Guangxi,China. In the six reclaimed minesoils,the heavy metal concentrations were Pb 41.63-348. 31 mg · kg^-1,Cr 48.12-287. 29 mg · kg^-1,Zn 47. 38-69. 92 mg · kg^-1,Cu 12. 71-138.03 mg·kg^-1,Cd 0. 73-46. 50 mg · kg^-1,and Mn 676.7-41 996.4 mg · kg^-1 respectively. The highest Mn and Cd concentrations were 243 and 754 times of their respective soil background values for Guangxi. With the fuzzy comprehensive assessment methods ,the single factor decisive model assessment showed that the average subordinate degree to Class Ⅱ （China Soil Quality Standard） was 0. 434-0. 981,and the weighted average model assessment showed that the subordinate degree was 0. 366-0. 974. Except Xialei,the other five restored minesoils had subordinate degrees to Class Ⅱ exceeding 0. 7,with the heavy pollution rates being 100%. Cd is the principal contaminants in these reclaimed minelands. Therefore,the reclamation of Mn mine wasteland for edible crop plantation is to be avoided at the early stage of mineland restoration.