The Effects of Aquatic Plant Vallisneria Natans on the Distribution of Metals under Different Hydrodynamic Conditions

Abstract

Heavy metals will be released to the water column during the sediment resuspension, causing the secondary pollution to the water ecosystem. In this study, the sediment collected from Zhushan Bay was placed in three similar pneumatic annular flumes where the wind speeds supplied by blast blowers were 3.21m/s, 5.95m/s and 8.78m/s respectively. The physicochemical parameters of the water and concentrations of metals in the water, plants and sediment were measured during the relevant experiments. The result showed that the concentrations of metals in the overlying water increased while it decreased in the pore water with the hydrodynamic disturbance. The aquatic plant Vallisneria natans bioaccumulated metals in the sediment and water, and the plant roots showed a higher ability in assimilating metals than the leaves. Meanwhile a positive correlation was found between wind speed and release amount of metals in pore water. In addition, the relationship between the wind speed and the biota-sediment accumulation factor (BSAF) was different due to the different features of metals.