Variation of Bioavailable Phosphorus in Yueliang Bay of Tai Lake Under Sediment Disturbance Conditions

By using algae to determine the bioavailable phosphorus(BAP),the variations of BAP in overlying water and on the suspended solids were investigated and the bioavailability of dissolved total phosphorus(DTP)was analyzed under repeated disturbance with high intensity,with the sediments and overlying water from Yueliang Bay in Tai Lake.The results showed that the concentrations of BAP in the overlying water increased due to sediment disturbance,but it was lower than DTP,indicating that part of DTP was not bioavailable.On the contrary,the concentrations of BAP on the suspended solids decreased under sediment disturbance,indicating that sediment disturbance could improve transformation of phosphorus from bioavailable forms to nonbioavailable forms on the suspended solids.Therefore,the bioavailability of particulate phosphorus decreased from 7%(7 d)to 2.5%(21 d)with the experiment time extending.It was calculated that the percentage of bio-DTP to DTP was 77%,using the concentrations of BAP on the suspended solids to determine the bioavailable particulate phosphorus(BAPP)in the overlying water.The BAP in the overlying water and on the suspended solids was lower marked using algae,compared with chemistry methods.Moreover,the trends of both BAP using algae were different from those using chemistry methods.It is suggested that the previous studies may overestimate the contribution of internal phosphorus release to eutrophication in shallow lakes.