Taking Taihu Lake as the research object, for the aged polystyrene microplastics (PSMPs), the influence of hydraulic disturbance intensity on the migration process of PSMPs between mud and water phases was discussed, and the morphology and elements of PSMPs were analyzed using microscopic characterization methods including FTIR and SEM-EDS, as was done for characterization. The results showed that under disturbance conditions (55 r·min-1 and 120 r·min-1), the suspended solids (SS) and PSMPs in the overlying water were higher than those in the control experiment. This was due to the fact that the PSMPs were affected by buoyancy and reunited on the water surface under undisturbed conditions. Under low-intensity (55 r·min-1) disturbances, SS and PSMPs in the overlying water were (264.67±16.01) mg·L-1 and (239.67±6.51) n·mL-1, respectively, and (120 r·min-1) under high intensity. Under disturbance, the SS and PSMPs in the overlying water were (264.67±16.01) mg·L-1 and (239.67±6.51) n·mL-1, respectively. In the bottom mud, PSMPs were (491.00±23.46) mg·L-1 and 2.00 n·mL-1, respectively. Additionally, according to the SEM-EDS analysis, the surface of PSMPs had sediment elements (Si, etc.), which showed that it was easier to promote the adsorption of PSMPs by suspended solids under high strength. The abundance of PSMPs in the sediments also confirmed that the greater the intensity of the disturbance, the easier it was to promote the migration of PSMPs to the sediments.
Keywords: DLVO theory; Taihu Lake; disturbance intensity; migration; polystyrene microplastics (PSMPs).