Abstract

Sediments play an important role in the overall equilibrium conditions in eutrophic surface water, which is determined by the nutrient concentration mainly Phosphorus (P). Sorption tests were performed for sediments from Lake Caron and Huron River. By taking the originally sorbed P ( S 0 ) into consideration, the experimental data were fit to the modified Langmuir and Freundlich isotherms. The modified Langmuir isotherm was used to obtain the maximum sorption capacity ( S max ) as its values varied between 100 to 5000 mg-P/kg. Sediments might act as a source or sink of P. The equilibrium concentration at zero sorption ( EPC 0 ) between the water column and sediments was calculated, for the sediments from Lake Caron showed a wide range from 0.043-0.31 mgP/L, and the sediments might act as potential source of Pinto the water, except for CS3 which might act as a sink. For the Huron River EPC 0 values are in the range of 0.15-0.18 mg-P/L. The adsorption kinetics were studied and modeled as the power function, and the half life time of P by the sediments was determined. Soluble reactive phosphorus ( SRP ) concentration changes in the water by resuspension was observed over a period of 4 days. More analysis for SRP changes was performed, to included the effect of sediments to solution ratio, resuspension and the background electrolyte. The effect of particle size fraction on the sorption models for CS3 was evaluated and S max was 5800 mg-P/kg for a particle size less than 38om and 910 mg-P/kg for the particle size of 75 om -2mm, which indicates the smaller the particles size the more the ability to adsorb P.