Phytoremediation of heavy metals: the role of macrophytes in a stormwater basin

The aim of the study was to test the efficiency of aquatic vegetation to assimilate heavy metals and allow biological epuration in a stormwater basin. Through a periodical collection of water, sediments and macrophytes, a decrease of heavy metals concentrations was investigated from the inlet to the outlet of the basin. No evidence of metal reduction was noticed in the waters due to a general low level of heavy metals. However, accumulation of metals is greater in the sediments and decrease from the inlet to the outlet (47% reduction for Cd, 30% reduction for Pb, 75% reduction for Zn). Some specific organs of macrophytes accumulate heavy metals in various concentrations : Elodea canadensis (all organs merged) and crowns of Glyceria maxima, Sagittaria sagittifolia, Scirpus lacustris, Typha latifolia contain the highest concentrations in Cd, Pb and Zn.