Assisted phytoremediation of heavy metal contaminated soil from a mined site with Typha latifolia and Chrysopogon zizanioides

Chemically assisted phytoremediation is fast gaining attention as a biotechnology to accelerate heavy metal removal from contaminated substrates, but how different chemical amendments affect the process remains an important research question. Here, bioaccumulation factor (BAF), translocation factor (TF), removal efficiency (RE) and uptake of Hg, As, Pb, Cu and Zn by cattail (Typha latifolia) and vetiver (Chrysopogon zizanioides) were quantified in a potted experiment to determine the effects of amendments on the phytoremediation success. Baseline concentrations of heavy metals within the studied mined site were determined. The experiment involved three soil treatments (each comprising 16 samples amended with 0.05 mol/L ethylene di-aminetetraacetic acid (EDTA), 3 g of aluminum sulfate [Al2(SO4)3], and unamended control) transplanted with equal numbers of vetiver and cattail. Growth performance (height) of plant species was monitored every two weeks. Sixteen weeks after transplanting, heavy metal levels in plant and soil samples were quantified following standard protocols, and the biomass and root length measured for each plant species. Results indicated strong negative impact of mining activities on heavy metal levels of soil in the study area. Soil amendment considerably enhanced the BAF, TF, RE and uptake but the effect varied with plant species and heavy metal in question. The amendment also stimulated strong positive correlation between RE and BAF, TF and metal uptake, and generally did not show any negative effects on plant growth performance. In general, soil amendment aided the accumulation and translocation of heavy metals in the plant species studied, and could be explored for cleaning up contaminated sites.