Phytoremediation of Polluted Waters Potentials and Prospects of Wetland Plants

To investigate the possible use of plants to remediate polluted waters, a pot experiment was carried out in the laboratory with five wetland plant species, i.e., sharp dock (Polygonum amphibium L.), duckweed (Lemna minor L.), water hyacinth (Eichhornia crassipes), water dropwort [Oenathe javanica (BL.) DC.] and calamus [Lepironia articulata (Retz.) Domin]. Nitrogen (N), phosphorus (P) and three heavy metals, cadmium (Cd), mercury (Hg) and lead (Pb), were the objects of remediation. Sharp dock was found to be a good accumulator of N and P. Indeed, on a dry weight basis the shoots of sharp dock accumulated up to 6.4% of N and 1.1% of P with BCF (bioconcentration factor) values of 2235 and 1568, respectively. Water hyacinth and duckweed strongly accumulated Cd with concentrations of 462 and 14200 mg/kg, respectively, and BCF values of 1225 and 2567, respectively. Water dropwort achieved the highest concentrations of Hg, i.e., 1.2 mg/kg with a BCF value of 807, whereas calamus achieved the highest concentrations of Pb, i.e., 512.4 mg/kg in its roots with a BCF value of 1217. Thus, it could be concluded that the above plant species are good candidates for phytoremediation of polluted waters, as follows: sharp dock through accumulation of N and P in its shoots, water hyacinth and duckweed as hyperaccumulators of Cd, water dropwort as an hyperaccumulator of Hg and calamus as an hyperaccumulator of Pb.