Phytoremediation of heavy metals and rhizosphere detection of bacteria in a drainage river sediment
2012, 2012 (1):
Concentrations of heavy metals (Pb, Zn, Cr, As, Ni, Cu and Cd) in a drainage river sediment were determined from the industrial area of Harbin city in Heilongjiang Province. Pot experiment was conducted to evaluate the potential of four spontaneous plants, 〖WTBX〗Zea mays 〖WTBZ〗L., 〖WTBX〗Polygonum lapathifolium 〖WTBZ〗L., 〖WTBX〗Solanum nigrum〖WTBZ〗 L. and 〖WTBX〗Rumex patientia〖WTBZ〗 L. for heavy metals phytoremediation in the drainage river sediment contaminated with industrial effluent. The results revealed that the sediment was polluted by heavy metals. The contents of residual fractions of the 7 heavy metals decreased, while the Fe-Mn oxide fractions and exchangeable fractions consistently increased via two-season cultivations. Sequential extraction results confirmed the capability of the four plants to increase the bioavailability of these heavy metals. The concentrations of heavy metals in sediments and plants were in the same trend: Zn＞Pb ＞Ni＞Cr＞Cu＞As＞Cd, which reflected the biomonitoring potentialities of the tested plants. The heavy metals accumulations and translocations of the four plants were investigated. The results showed that the plants accumulated more Zn and Ni than the other metals; and the concentrations of Cu in shoots were low. Zinc and Ni levels in plant samples ranged from 108.4 mg/kg in shoots to 543.92 mg/kg in roots and 36.8 mg/kg in shoots to 246.91 mg/kg in roots of different species, respectively. Generally, the four species excluded multiple metals from the shoot tissues and accumulated in root zones, behaving as tolerant plants. However, polygonum lapathifolium L., Rumex patientia L. and Solanum nigrum L. showed high Pb, Zn and Cd shoot accumulation with high metal translocation factor (TF>1), respectively. It suggested the three species had phytoextraction potentialities. In addition, florescence in situ hybridization (FISH) was used to analyze the amount and distribution of bacteria in the rhizosphere sediment. It suggested the four plants have effect on bacterial activations.
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