• • Sediment elutriation achieved average reductions of 5.11% for organic matter, 10.19% for total nitrogen (TN), and 8.71% for total phosphorus (TP) in the top 0–30 cm sediment layer, directly lowering the internal nutrient load that fuels eutrophication and black-odor events.
• • Water quality improved concurrently: chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N) removal rates averaged 35.67% and 22.65%, while transparency, dissolved oxygen (DO), and oxidation-reduction potential (ORP) increased by 102.46%, 11.07%, and 15.66%, respectively—critical for restoring aerobic conditions and suppressing anaerobic decomposition.
• • The treatment shifted sediment particle size distribution: clay content decreased by 8.87%, sand content increased by 12.37%, and D50 and D90 increased by 32.39% and 159.97%, forming a stable coarse-grained layer that physically prevents sediment resuspension and pollutant release.
• • Mechanical disturbance and particle size redistribution enhanced oxygen transfer at the sediment-water interface, increasing the abundance of facultative anaerobic phyla (e.g., Chloroflexi, Spirochaetes), which suppressed anaerobic fermentation and the generation of odorous gases (H2S, NH3), thereby reducing malodor and sediment upwelling.