Effect of sediment resuspension frequency on bio-availability of particulate phosphorus in overlying water
沉积物悬浮频率对水体颗粒态磷生物有效性的影响

Lab-scale experiments were conducted to investigate the effect of sediment resuspension under different frequency conditions on bio-availability of particulate phosphorus (PP) in the overlying water. The results show that the bio-availability of PP decreased obviously under sediment resuspension conditions, compared with the initial state. After 30 d, the percentages of algal available phosphorus (AAP) to total phosphorus (Tot-P) in suspended solids were 26.24% (lower frequency) and 20.04% (higher frequency) of the initial state (56.75%), respectively. Sequential fractionation indicated that the proportions of non-occluded Fe/Al-P (AAP) to Fe/Al-P decreased gradually under sediment resuspension conditions with time increasing, although the concentrations of Fe/Al-P increased markedly in suspended solids. This was attributed to dissolved oxygen (DO) penetration and pH values change. Under sediment resuspension conditions, DO concentrations increased from 3 mg·L-1 (initial state) to 6 mg·L-1 (the end). In addition, pH values decreased from 8.02 (initial state) to 7.80 (lower frequency) and 7.60 (higher frequency), respectively. The concentrations of bio-available particulate phosphorus (BAPP) and dissolved total phosphorus (DTP) reduced under sediment resuspension conditions. Correspondingly, the content of bio-available phosphorus (BAP) decreased in the overlying water, compared with the initial state.