Soil Heavy Metal Pollution Of Dabaoshan Mine And The Ecological Rehabilitation Technelogy For Abandoned Mining Area

The soil samplings, collected in the main functioning areas of Dabaoshan Mine inGuangdong province, were analyzed, and their pollution situation and migrating patterns werestudied. According to the heavy metal pollution factors, the manure and hydrated lime, used assoil improver were added into the soil samples with different ratios. Then the physical andchemical properties and the changes of heavy metal forms were tested. An optimum ratio wasfinally determined by analyzing plants' performance influenced by toxic soil. Plants suitable formining area vegetation restoration were screened through analysis of heavy metal content inroots, shoots and leaves and investigation of plant community and sample collection of dominantspecies in mining area. Vegetation restoration were then achieved in further planting test inmining area. The main research results are showed as follows:(1)Soils of Dabaoshan mining area have been severely polluted by heavy metal, threateningthe down stream's ecological security. Pollution level ranged from high to low, in the order as:Dew mining, tailings, dump and Production living areas, with unqualified rate of samplesexceeding100%. Soil pH and nutrient was considered as the main factors in controlling heavymetal content.(2)The water quality in coincidence with content of heavy metal element, including Cu, Znand Cd, in the downstream badly exceeds the state standard. A strong infiltration capability wasconsidered of Cu and Pb in substrate. A distributing gradient was built up as the soil heavy metalcontent beside the riverbank decreased from the upstream to downstream, while decreasing as theincrease of distance from the riverbank.(3)The significantly improved quality of soil in mining area, as well as the reduced heavymetal content and toxicity, were indicated after hydrated lime and manure were added. Thelowest toxicity was considered in seed germinating experiment with the sixth treatment, in which10g/kg hydrated lime and30g/kg manure were added, indicating an optimal proportion.(4)Panicum repens L. and Paulownia fortunei were Cu-related and Pb-relatedhyperaccumulators. Pennisetum purpureum, Ishaemum indicum, Dicranopteris dichotoma,Miscanthus floridulu and Pinus massoniana all have strong resistance to multi-heavy-metal stress.In the outdoor planting test, the average survival (germination rate) and retention rate of nineexperimental plants, in the occurrence of improved polluted condition, were94%and88%respectively, while rate of46%and22%respectively were shown in control group. And averageheight of plants in treatment group was1.6times than that of control.