底泥扰动对上覆水中磷形态分布的影响

通过室内试验模拟底泥受持续和间歇扰动的过程.探讨了扰动作用对上覆水中不同形态磷分布的影响.结果表明,持续扰动和间歇扰动显著促进了上覆水中的溶解态磷向底泥迁移.持续扰动与间歇扰动作用下,上覆水中溶解性无机磷(DIP)分别在第6h和第24h达到平衡状态,为0.014mg.L-1和0.015mg.L-1.显著低于对照试验(0.04mg.L-1);而溶解性总磷(DTP)则在第6h和第48h达到平衡状态,为0.047mg·L-1和0.045mg.L-1,显著低于对照试验(0.065mg.L-1).持续扰动促进了颗粒态磷(PC)的释放,扰动6h后,PP达到最大值(9.18mg·L-1).随后下降.第24h后,PP稳定在2.18mg·L-1左右;而间歇扰动作用下,第2h,PP达到最大值(2mg·L-1),随后下降,第96h后,PP稳定在0.093mg·L-1左右.扰动作用下,TP的变化规律与PP一致.与初始状态相比,持续扰动和间歇扰动作用下,DIP/DTP、DIP/TP、DTP/TP显著下降,而上述该值在对照试验中则基本保持不变,说明扰动导致的底泥再悬浮有利于降低上覆水中溶解态磷的含量.

Effect of sediment disturbance on the distribution of phosphorus forms in the overlying water

Lab-scale experiments were conducted to investigate the effect of continuous or intermittent sediment disturbance on the distribution of different forms of phosphorus in the overlying water. The results show that the migration of dissolved phosphorus from water to sediment was enhanced by both continuous and intermittent disturbance, as compared with the control. Equilibrium concentrations of dissolved inorganic phosphorus (DIP) in the overlying water were reached after 6 h continuous disturbance (0.014 mg·L-1) and and 24 h of intermittent disturbance (0.015 mg·L-1). Both of the conditions led to lower DIP than the control (0.04 mg·L-1). The equilibrium of dissolved total phosphorus (DTP) in the overlying water was reached after 6 h of continuous disturbance (0.047 mg·L-1) and 48 h of intermittent disturbance (0.045 mg·L-1). Again, DTP after disturbance was lower than the control value (0.065 mg·L-1). Continuous disturbance promoted the release of particulate phosphorus (PP) from the sediments. The highest value of PP in the overlying water (9.18 mg·L-1) was reached after 6 h. The content of PP dropped as the disturbance continued, remaining at about 2.18 mg·L-1 after 24 h. Under conditions of intermittent disturbance, the highest value of PP in the overlying water (2.00 mg·L-1) was reached after 2 h and then PP decreased. The content of PP remained at about 0.093 mg·L-1 from 96 h to the end of the experiment. Under both disturbance conditions, the variation of total phosphorus (TP) was the same as PP. DIP/DTP, DIP/TP and DTP/TP decreased markedly under the disturbances compared with the initial state, but the ratios were almost unchanged in the control experiment. Therefore, the study reveals that sediment re-suspension caused by disturbance facilitates reduction of the content of dissolved phosphorus in the overlying water.