广西思荣锰矿复垦区的重金属污染影响与生态恢复探讨

Impact of Heavy Metal Contamination in the Reclaimed Mn Mineland in Si-rong,Guangxi and Suggestions for Ecological Restoration

思荣锰矿区是我国著名的广西八一锰矿的两大矿区之一,历经近50a露天开采,生态环境破坏严重。通过对思荣复垦区的甘蔗园、柑桔园和茶园区土壤及其部分植物进行采样和分析,探讨了复垦区的重金属污染影响及生态恢复途径。结果表明,该复垦区土壤Cd含量超过土壤三级标准值的30多倍,Cd、Pb、Cr及Mn等是复垦区土壤和植物的主要毒害元素,在甘蔗茎、花生仁和茶叶中的Cd、Cr、Pb的含量均严重超过食品中污染物限量标准。因此,该矿区受Mn、Cd、Pb、Cr复合污染严重的废弃地一般不宜种植食用农作物和水果,应发展当地传统种植且有较大经济效益的非食用性经济作物,如剑麻、黄麻、红麻及作乙醇原料的玉米、木薯作物等,此外也应重视利用植物修复技术治理重金属元素污染废弃地,以促进恢复土壤的生态功能和永续利用。

Si-rong manganese mineland is one of the two sub-regions constituting the famous Bayi Manganese Mine, China. Through nearly 50-year opencast mining, the natural environment and ecological equilibrium have been severely disturbed in this mineland. Extensive soil sampling was made in the reclaimed sugarcane field, orange field and tea garden, and meanwhile, the major plants were also collected for determination of heavy metals. The results showed that the soil Cd concentration was over 30 times the Soil Quality Standard value （Class Ⅲ ）. Cd, Pb, Cr and Mn were the main toxic metal elements in soil and for higher plants in this region. The Cd, Cr and Pb levels in sugarcane, peanut and tea leaf exceeded the maximum allowable limits of contaminants in food. Therefore, this mine wasteland was contaminated by multiple metals and could not meet the requirements of soil for agricultural cultivation, unsuitable for plantation of edible crops and fruits. However, other agronomic fiber crops, such as sisal, jute, and ambary, and fuel crops （for alcohol production）like maize and cassava can be used for cultivation. In addition, new phytoremediation techniques should be used to remediate the heavy-metal contaminated wasteland before the agricultural utilization, thus, the soil functions can be restored and a sustainable utilization can be achieved.