Effects of hydrodynamics processes on phosphorus fluxes from sediment in large, shallow Taihu Lake

The turuovor of phosphorus (P) in lake sediments,a major cause of eutrophication and subsequent deterioration of water quality,is in need of deep understanding.In this study,effects of resuspension on P release Were studied in cylindrical microcosms with Y-shape apparatus.The results indicated that there was a positive correlation between flux of suspended substance across sediment-water interface (Fss) and the wind speed,and an increasing Fss during each wind process followed by a steady state.The maximal Fss under light,moderate,and strong wind conditions were 299.9±41.1,573.4±61.7,and 2093.8 215.7 g/m2,respectively.However,flux of P across sediment-water interface (Fp) did not follow a similar pattern as Fss responding to wind intensity,which increased and reached the maximum in initial 120 min for light wind,then decreased gradually,with maximal flux of 9.4±1.9mg/m2.A rapid increase of Fp at the first 30 min was observed under moderate wind,with maximal flux of 11.2±0.6mg/m2.Surprisingly,strong wind caused less Fp than under light and moderate wind conditions with maximal flux of 3.5±0.9mg/m2.Fss in water column declined obviously during the sedimentation process after winds,but Fp varied with wind regime.No obvious difference was detected on Fp after 8 h sedimentation process,compared with the initial value,which means little redundant P left in the water column after winds.