桂北锰矿废弃地主要植物种类调查及土壤重金属污染评价

采用样方法和实地勘查法调查了桂北荔浦锰矿区废弃地自然定居和人工种植的植物,并且对8个区的主要植物及其土壤重金属含量进行了分类、测试。并采用污染指数评价法对矿区废弃地土壤重金属的污染程度进行了评价。结果表明,白茅(Imperata cylindrica)、马唐(Digitaria sanguinalis)、飞蓬(Erigeron acer)、苍耳(Xanthium sibiricum)、耳草(Hedyotisauricularia)对重金属有较强的耐性,而且能适应废弃地的不良环境,可作为锰矿废弃地生态恢复的先锋植物;用3种不同的背景值对废弃地土壤重金属污染程度的评价结果是一致的,除Pb外,5种重金属元素单项污染指数均大于2,表示被污染,其中以Mn、Zn、Cd污染最为严重。锰矿废弃地人工复垦采用典型的农业恢复模式,以种植果树和经济作物为主,果实中Cr、Cd的含量均超过食品卫生限量标准,因此矿山恢复的早期不宜直接种植果树和食用经济作物。以上研究结果可为锰矿废弃地的生态恢复和植被重建提供科学依据。

Investigation of main plant species and assessment of soil heavy metal pollutions in manganese mine wastelands in north Guangxi

An extensive ecological survey and sampling of soils and plants by plant sample technique and spot reconnaissance were made in Lipu manganese mine wastelands in north Guangxi. Dominant plant species from eight section areas were classified and soil heavy metal concentrations in related sections were determined. Estimations of the degree of heavy metal pollution were made for the area using polluting index apprise. The result showed that Imperata cylindrical,Digitaria sanguinalis,Erigeron acer,Xanthium sibiricum and Hedyotis auricularia are the species with high tolerance to heavy metal pollutions adapted to the adverse conditions of wastelands. These species can be used as pioneer plants for recovery of the vegetation in the manganese-mined wastelands. The indi-vidual event pollution index of the heavy mentals,compared to their background values are higher than 2,with Pb as an exception,indicating that the soil in these areas has been contaminated and that Mn and Cd are the elements creating most serious pollution problems. Typical agricultural utilization pattern was common in the restoration of manganese mine wastelands in Guangxi. However,the concentrations of Cr and Cd in the edible parts of economic crops were higher than the prescribed limits by China Food Safety Stan-dards,and thus they were not safe for consumption. Planting orchards and other edible economic crops are not suitable cultivation species directly used in the wastelands particularly in the early stage of ecological restoration.,The object of the work is to provided science gist of zoology resume and vegetation rebuild in manganese mine wastelands.