Influence of the vegetative cover on the fate of trace metals in retention systems simulating roadside infiltration swales

Abstract Large-scale outdoor mesocosms were designed and co-contaminated with metals (Cd, Pb, Zn) and organic compounds to better understand the complex functioning of urban roadside swale environments. Infiltration systems were planted with macrophytes ( P . arundinaceae , J . effusus and I . pseudacorus ) or grassed, and natural or spiked target metals were monitored over two years. In the non-spiked mesocosms, atmospheric metal inputs were slightly higher than outputs, leading to low metal accumulation in topsoils and to very low outflow water contamination ( P . arundinacea and grass. Metal phytoextraction in plant aerial parts was also better for grass and P . arundinacea , when considering metal standing stocks instead of their concentration in plants. J . effusus was a good metal accumulator, but its low aboveground biomass development was less favorable to metal removal through harvesting.