Phytoreme Diation of Heavy Metals Contaminated Environments: Screening for Native Accumulator Plants in Zanjan-Iran

Environmental pollution with heavy metals is a global struggle. Phytoremediation is an effective and low-cost technology for refinement of polluted soils. This research was conducted in Zanjan province (located in North West Iran) where metallurgical industries are developed quickly. In this study, based on the heavy metals contamination of soil in the studied area six sampling sites were selected taking into account the industrial distributions as well as the low/high traffic congestions. Leaves from eight tree species namely: Populus nigra, Ulmus pumila, Fraxinus excelsior, Robinia pseudoacacia, Acer hyracanum, Salix alba, Thuja orientalis, and Cupressus sempervirens var arizonica, were sampled and analyzed by ICP-OES (Spectro Genesis) for their heavy metal contents (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb). Results showed that heavy metals in stations close to the lead and zinc smelting industrial complexes are much higher than average showing a high correlation with their respective metal concentrations in soils. This clearly indicates that heavy metal contents in tree leaves in the studied area are solely related to industrial activities notably National Iranian Lead and Zinc (NILZ) as well as Zinc Specialized Industrial Complex (ZSIC) companies. Based on the results, the studied native plants accumulate different metals selectively and Populus nigra was found to be the best accumulator plant for Mn, Zn and Cd, Thuja orientalis, as the best phytoextractor for Fe, and Cupressus sempervirens var arizonica is the best species among the studied native plants for accumulation of Pb.