Remobilization of heavy metals during the resuspension of Liangshui River sediments using an annular flume

The release and transport of heavy metals(Ni,Cr,Cu and Pb) from Liangshui River sediments into the overlying water column during the resuspension event were determined using an annular flume with a velocity ranging from 0.15 to 0.35 m/s.It is shown that the suspended particulate matters(SPM) increased as much as nearly 25 times from 165 to 4220 mg/L as the velocity increased.Heavy metals showed an increase in dissolved phase as the velocity increased due to their desorption from the SPM.Acid-soluble heavy metals increased as the velocity increased,indicating that part of the heavy metals transformed from stable phase to labile phase during resuspension.Heavy metal concentrations in the SPM on volume normalization increased by approximately 2-6 times.However,on the mass weighted basis they decreased,approaching the bulk-sediment contents at high velocity,due to the "particle concentration effect".The distribution coefficients(K D) of heavy metals were higher at slower velocity during the sediment resuspension,which could be attributed to the decrease of fine particles(silt/clay fraction) during resuspension.