A modified QWASI model for fate and transport modeling of Zn and Pb in a shallow lake during the ice-free period.

Heavy metal pollution in lakes is becoming increasingly of interest to researchers. Because heavy metals have high mobility and do not degrade, they migrate easily between different environmental mediums through processes such as suspended solids deposition, sediment resuspension, and diffusion, among others. These processes are particularly pronounced in shallow lakes since the hydrodynamism is higher in bodies of water with minimal depth. Lake Ulansuhai-a typical shallow lake in the Hetao irrigation district in Inner Mongolia-also experiences intense sandstorm activity, which compounds the suspended solids exchange intensity between water and sediment, strengthening the migration of heavy metals in the lake system. This study examines the fate and transport of two heavy metals-Zn and Pb-within this lake, using a field experiment to determine the flux of sediment re-suspension and deposition and a laboratory experiment to modify the QWASI model for shallow bodies of water. The aquivalence and mass balance approaches were used to develop this modified QWASI model. The margins of error between the modeled and the measured average concentrations of Zn and Pb in water were 5.0%-30.6% and 5.8%-29.5%, respectively, and in sediment were 0.3%-4.9% and 0.9-5.5%, respectively. These results suggest that the modified QWASI model developed here could indeed be used to more accurately represent the fate and transport of Zn and Pb during the icefree period of a shallow lake.