[Impacts of sediment disturbance time on the distribution of phosphorus forms in suspended solids]

To examine the impact of sediment disturbance time (disturbance 10 min and 9h, respectively) on the transformation of phosphorus forms in suspended solids, the microcosm experiment was carried out with sediment and lake water from Yueliang estuary in Taihu Lake. The transformation of phosphorus forms in suspended solids was analyzed. The longer disturbance time, the greater of dissolved total phosphorus (DTP) in the overlying water was observed. However, in the control experiment, the concentration of DTP was higher than that in the disturbance experiment. Sequential fractionations indicted that mass fraction of Fe/Al-P to Tot-P in the suspended solids decreased gradually under disturbance conditions (10 min, 9 h) with increasing the experiment time, and then, the values decreased to 42.5% (10 min) and 38.1% (9 h) at 10 d, respectively. At the end, they increased slightly, compared with the values at 10d. However, mass fraction of HCl-P to Tot-P in the suspended solids increased gradually with time, and then went up to the highest (48.9%, 10 min and 53.7%, 9 h) value at 10 d. It suggested that sediment disturbance promoted the transformation of phosphorus forms in the suspended solids, especially from mobile phosphorus forms to refractory forms.