Uptake and allocation of selected metals by dominant vegetation in Poyang Lake wetland: From rhizosphere to plant tissues

摘要

Wetland plants have shown much potential for the removal of metals from soils by accumulating in plant tissues. Therefore, analysis of the metal accumulation and translocation capabilities of wetland plants is important for effective phytoremediation of heavily polluted wetlands. However, few studies have been conducted to analyze metal accumulation in metal-contaminated wetlands of Poyang Lake, China. The aim of this study was to investigate the absorption and transportation characteristics of metals (Cr, Ni, Cu, Zn, Cd, Pb) in five dominant plant species (i.e. Phragmites australis (Cav.) Trin. ex Steu, Triarrhena lutarioriparia L Liu, Carex cinerascens Kukenth., Artemisia selengensis Turcz. ex Bess., Phalaris arundinacea Linn), in three wetlands of Poyang Lake (China). The pollution assessment indicated that the studied wetlands were all polluted by metals with PLI (pollution loading index)> 1 and Cd was the main pollutant presenting a high ecological risk. The metal concentrations in different plant tissues did not exceed either the toxic critical values or the hyperaccumulation critical values. Bioaccumulation factor (BAF) and translocation factor (TF) were used to clarify the accumulation and translocation characteristics of metals by wetland plants. Triarrhena and Artemisia showed significantly high BAF values for Cd (8.26 and 4.31, respectively); this indicated their suitability and potential for Cd phytostabilization. The significantly high TF values of Cd (5.29) and Pb (3.25) in Phragmites indicated its ability for Cd and Pb phytoextraction. The high BAF and TF also indicated the high potential of Triarrhena, Artemisia and Phragmites as hyperaccumulators. The correlation analysis and multiple statistical analysis indicated that interactive effects of soil properties on metal accumulation are more significant than any single soil property, and influence of soil properties may partly depend on plant species. This study provides valuable information for phytoremediation of metal contaminated wetlands with suitable plant species.