Effect of Different Sediment Resuspension Modes on Particulate Phosphorus Bioavailability in Overlying Water

Effect of different sediment resuspensions such as disturbing sediments and aerating to sediments on bioavailable particulate phosphorus(PP) were studied,with sediment taken from Moon Bay in Taihu Lake as materials.Results showed that bioavailability of PP decreased under sediment resuspension conditions.After 10 d,the percentages of algal available phosphorus(AAP) to total phosphorus(TP) in suspended solids were 34.75% for disturbing sediments and 17.03% for aerating to sediments of initial state 39.86% respectively.Sequential fractionation indicated that Fe/Al-P and proportions of non-occluded Fe/Al-P(AAP) to Fe/Al-P decreased gradually under sediment resuspension conditions with time increase,which was attributed to dissolved oxygen(DO) penetration and pH values change.Under sediment resuspension conditions,DO concentrations increased from 2.59 mg/L(initial state) to 5 mg/L(disturbing sediments) and 7.3(aerating to sediments) respectively.Bioavailability of particulate phosphorus is in a sudden increase by the end,and the reasons of the sudden increase in bioavailability of particulate phosphorus by the end are very complex.Maybe it is related to physical and chemical changes in sediment under sediment resuspension and role of microorganisms in water,which need further studies.The concentrations of bioavailable particulate phosphorus(BAPP) and dissolved total phosphorus(DTP) reduce under sediment resuspension conditions.Correspondingly the contents of bioavailable phosphorus(BAP) decrease in overlying water,compared with initial state.