Physicochemical Properties and Environmental Effects of Suspended Sediment Particles in the Largest Freshwater Lake, China

Abstract

Suspended sediment particles (SSPs) act as a potential source of and sink for aquatic pollution. This study sampled six sites in Poyang Lake in August and November 2019. Changes in the physicochemical properties of SSPs were analyzed using scanning electron microscope energy-dispersive spectrometry (SEM-EDS). The results showed that SSPs consisted mainly of clay and chalk, with an average content of 39.71% and 57.52%, respectively. The average particle size distribution of SSPs in the study area ranged from 5.54 to 15.97 μm and the spatial distribution pattern showed the north lake area (I) > west lake area (II) > east lake area (III). The angle (K) of morphological indicators varied widely, with coefficients of variation between 0.25 and 1.23. Water-flow velocity was negatively correlated with SSP size, while suspended-solid concentration was positively correlated with SSP surface roughness. Morphological parameters, chemical composition, and correlation between each SSP form were analyzed to identify morphological distribution characteristics. Linear regression equations estimated endogenous phosphorus load in zones I, II, and III as 1027.202 mg/kg, 1265.343 mg/kg, and 1013.111 mg/kg respectively. Therefore, we conclude that the morphological differences in particulate matter, the interaction between chemical fractions, and the aqueous environment affecting the distribution of phosphorus fugitive forms, may contribute to endogenous lake pollution. These results are essential for revealing the intrinsic relationship between SSP physicochemical properties and lake eutrophication and studying other water–sediment interface processes of lake pollutants.