【摘要】 利用模拟池塘微生态系统开展长期暴露毒性实验 ,研究了铜矿尾矿砂中重金属在各个环境介质中的迁移及其生物有效性。实验结果较好地反映尾矿库湿地系统中重金属的生物毒性作用与生物可利用性。结果表明 ,适宜的重金属浓度会刺激生物生长与繁殖 ,而过高的重金属浓度则对生物的生长繁殖具有明显的毒性作用 ;微生态系统各组份间的重金属含量与尾矿砂中重金属含量具有良好的相关性 ,生物体内重金属累积与底泥尾矿砂中重金属浓度、种类和生物类属有关 ,试验研究为矿山生态修复过程的湿地利用提供重要的科学依据。更多还原

【Abstract】 Dexing copper mine, which lies in the northeastern Jiangxi Province, China, is one of the largest copper mine in Asia. No.1 mine tailings pond was abandoned in 1987, which resulted in a 210 hm 2 pond requiring stabilization with water cover. Mine tailings pond is of environmental concern for potential hazards in surface and groundwater, which may be uptake by vegetation and bioaccumulation in food chains. Diversity of landscape and stability of tailings is important to remain the manmade reservoir. The metal toxicity and the poor nutrient conditions are the major constrains in ecological reconstruction. The sediment is used to reduce the toxicity and improve the nutrient conditions in tailings. Speciation analyses, toxicity and organism exposure tests are frequently employed to assess the biotoxicity and bioavailability of heavy metals in the sediment. The objectives of the present study were to evaluate (1) the effect of heavy metals on biotoxicity and bioavailability in the mine tailings and (2) the possibility of rehabilitating the wet ecological system of mine tailings. In this study, a three-month organism exposure test in the micro-ecosystem was employed to determine the effect of heavy metals in the tailings and their transport to other environmental mediums from the sediment. Mine tailings collected from Dexing copper mine were mixed with paddy soil from Beijing at the rate of 0%, 20%, 40%, 50%, 60% and 100% (w/w, Mn, n=1~6, the representative of aquarium) as artificial sediments respectively and were spread to a 5cm-layer in six 60cm×30cm×45cm aquariums. They were statically flooded with tap water. Chlorella, Oedogonium and lilaeopsis noveazelandiae were transplanted into the micro-system two weeks later. Then fifteen tamed Cipangopaludina cathayensis were introduced to each aquarium after a second two weeks. Finally, six pieces of tamed gold fish were introduced to every aquarium and raised for two weeks before the end of the experiment. Meanwhile, the growth and reproduction of organisms were observed. The speciation of heavy metals in artificial sediments was analyzed for Cu, Zn, Mn, Ni, As, and Co after Tessier sequential extraction scheme. The content of heavy metals in the water and organ of tested organism was decomposed with HNO 3, H 2O 2 and HF in the OEM microwave oven and analyzed with ICP-AES. In the artificial sediment, most of heavy metals contained in the bioavailable fraction (40%~60%). Cu concentration in water increased with Cu concentration in the sediments. The ratio of Cu concentration in the phase of water and the total, carbonate, Fe and Mn oxides of in sediments was dramatic(r>0.95, n=5). These revealed that Cu would release into the water from the mine tailings. The Cu concentration in water was greater than the Water Quality Standard for fishery. Other metals with equivalent concentration in the water were contributed little to water quality. The growth and reproduction of organism reflect the biotoxicity of heavy metals. The heavy metals in mine tailing particles influenced the growth and reproduction of organism dramatically. The growth of Chlorella and Oedogonium were not observed during the experiment in all aquariums. The lilaeopsis noveazelandiae in M2 was more prosperous than in other ecosystems and its relative biomass was 382%(M2/M1). The lilaeopsis noveazelandiae in M6 contained tailings fully died during experiment. The growth of lilaeopsis noveazelandiae took on a trend of a parabola. This included that adequate concentration of heavy metal facilitated the growth and reproduction of grass, but excessive concentration restrained it. The relationship between the total concentration(C s) of Cu and biomass(Y) of lilaeopsis noveazelandiae was expressed by the equation of logY=-1.8979(logC s) 2+8.1342(logC s)-0.5299 (R 2 = 0.9247, n = 5). The growth and production of Cipangopaludina cathayensis were similar to that of grass and the fitting equation was Y=-4×10 -5 C s 2+0.0231C s+80.385 (Y is percentage of survival, R 2 = 0.9303, n = 5). Gold fishes could sur更多还原