Distribution of metals in water and suspended particulate matter during the resuspension processes in Taihu Lake sediment, China

Abstract

In this study, surface sediment from Zhushan Bay in Taihu Lake was subjected to resuspension under 6 different wind forces using a pneumatic annular flume. Water samples were taken at specific intervals, and the physicochemical parameters of the water column were monitored throughout the experiment. Concentrations of heavy metals (Cd, Pb, Cr, Ni, Cu, and Zn) in the sediment, water, and suspended particulate matter (SPM) were determined following standard methods. Total metal concentrations in overlying water increase with wind speed and the duration of the experiment. According to the principal component analysis (PCA), physicochemical factors, pH, dissolved oxygen (DO), and SPM all showed a close relationship with total metal content. Dissolved metal concentrations did not show significant variation. In contrast, a remarkable increase in the concentrations of metals was noted in the SPM in response to increases in wind speed and duration time of the study. Distribution coefficients (Kds) of metals between particulate and dissolved fractions generally appeared in the following order: Pb > Cr > Zn > Cu > Cd > Ni under six different disturbance conditions. However, the enrichment factors (EFs) of particulate metals generally appeared in the following pattern with respect to concentration: Zn > Pb > Cr > Cd > Cu > Ni. In general, the values of both indicators were directly proportional with as water turbulence. The results of this study may serve as a reference for distribution rules of heavy metals in water columns and SPM during sediment resuspension processes.