Control of sediment phosphorus release in lakes adding chemical reagents.

Objective To study the inhibit efficiency of lake sediment phosphorus release by adding chemical reagents and to provide the technical basis for the comprehensive management of city lake.Methods In May 20,2008,Mochou Lake upper sediment and water samples were collected.The phosphorus forms of sediments,total phosphorus(TP),NaOH-P,HCl-P,inorganic phosphorus(IP),organic phosphorus(OP) were analyzed and the pH value and content of TP in water samples were determined.Each water(250 ml)-sediment(10 g) system was respectively added by 0-1 000.0 mg/L of Ca(OH)2,2.0-10.0 mg/L of A12(S04)3 and 0-25.0 mg/L of FeCl3.The pH value and content of TP in water were determined,then the control rate of TP release were calculated.Results The pH values were between 7.6-8.0,TP content was 2.0 mg/L in water of Mochou Lake.The contents of TP,HCl-P,NaOH-P,IP,OP were 2 187.06,1 383.89,526.48,1 910.37 and 276.69 mg/kg respectively.With the increase of Ca(OH)2 concentration,pH value of water increased rapidly,content of TP showed a decreasing trend,control rate of TP release was increased.With the increase of A12(SO4)3 or FeCl3 concentration,pH value of water declined slightly,content of TP showed a decreasing trend,control rate of TP release was increased.Conclusion Ca(OH)2,A12(SO4)3,FeCl3 can significantly inhibit the phosphorus release of sediments in Mochou Lake.