PLUMBUM/ZINC ACCUMULATION IN SEEDLINGS OF SIX AFFORESTATION SPECIES CULTIVATED IN MINE SPOIL SUBSTRATE

Abstract

Mining activities generate spoils and effluents that are harmful to ecosystems and human health due to their extremely high toxic metal concentrations. Plants have been planted on these spoils to uptake heavy metal and to revegetate for phytoremediation. Soil obtained from Pb/Zn mine tailing areas was used to conduct a greenhouse pot experiment to compare the growth and toxic metal accumulation of six tree species for afforestation in southern China. One year growth indicated that the six species tolerated toxic metals and their accumulation differed with plant species, their parts and kinds of metals. Height and biomass of Betula alnoides were significantly greater than the rest of the species. Alnus nepalensis had the highest translocation (0.86 in root and 0.69 in shoot) and bioconcentration (0.62 in root and 0.51 in shoot) factor values for Pb, while Pinus yunnanensis had higher translocation and bioconcentration factor values (0.78, 0.45 in root and 0.84, 0.48 in shoot respectively) for Zn. Alnus nepalensis was the best candidate species for phytoremediation of Pb/Zn mine tailing areas due to its good nitrogen fixation, greater translocation and bioconcentration factor values and larger biomass, accumulating an average of 4.70 mg Pb and 6.92 mg Zn.