Accumulation of heavy metals in native plants growing on mining-influenced sites in Jinchang: a typical industrial city (China)

Such activities as mining, metal ore smelting and the discharging of mining wastes lead to heavy metal contamination. Phytoremediation, including phytoextraction and phytostabilization, has been considered for a long time to be effective in remediating metal-polluted soils. This research assessed the chance of 40 plants (35 species) distributing on mining-influenced sites for phytoremediation purposes. The results showed that total soil Ni, Cu, Cd, Cr and Co concentrations were in the ranges of 107-3045, 116-2580, 7.1-22.7, 115-897 and 23.2-144.3 mg kg(-1), respectively, whereas heavy metal contents in plants were in the ranges of 0.60-435.61, 2.41-298.31, 0.03-32.10, 0.08-88.20 and 0.11-28.52 mg kg(-1), respectively. Therefore, no species can be used for phytoextraction purposes because no hyperaccumulator was identified. Salsola passerine, Stipa capillata, Cynanchum Chinense and Halogeton glomeratus with translocation factor (TF) > 1 for all five metals were considered to be accumulators. All plants were observed to hold a bioconcentration factor (BCF) < 1, except for Caragana korshinskii, which had a BCF for Cd > 1, reflecting its low metal accumulation potential. Among the species studied, Oxytropis aciphylla, Salix matsudana, Tamarix hispida, Robinia pseudoacacia, Picea crassifolia, Lycium barbarum and Phragmites communis had both a BCF and TF < 1 for all five metals and were considered the most suitable for the phytostabilization of metal-polluted sites.