底泥扰动状态下内源磷释放过程模拟研究

Simulation of sedimentary phosphorus release under sediment disturbance

为了揭示底泥扰动对内源磷释放的影响,通过室内实验模拟了底泥多次扰动状态的整个过程。结果表明,底泥扰动刚结束（0 h）,溶解态磷（DIP、DTP）显著降低;底泥扰动结束后（1、6和24 h）,溶解态磷发生＂滞后释放＂。第1 d,在1、6和24 h采样时段,DIP、DTP的＂滞后释放量＂最大,分别达到20.0 1mg/kg,22.12 mg/kg,16.85 mg/kg和17.21 mg/kg,22.12 mg/kg,9.69 mg/kg。第2 d,该释放量分别降低了44.80%~57.87%和42.52%~61.24%。随着底泥扰动次数的增加,溶解态磷的＂滞后释放＂逐渐转变为＂负释放＂,同时,DIP/TP和DTP/TP逐渐降低。这说明,底泥扰动应该是促进了上覆水中溶解态磷向底泥的迁移和强化了底泥对磷的固定作用,同时降低了水体中磷的可生物利用性。因此推测,底泥扰动延缓了水体富营养化的发展进程。

The course of sediment disturbance time after time was simulated to study the effect of sediment disturbance on the release of sedimentary phosphorus.The results show that dissolved phosphorus（DIP,DTP） decreased markedly when sediment disturbance was over immediately（0 h）.However,delayed release was observed after sediment disturbance was over（1 h,6 h,24 h）.The amount of delayed release of DIP and DTP was the largest at 1st day,up to 20.01 mg/kg,22.12 mg/kg,16.85 mg/kg and 17.21 mg/kg,22.12 mg/kg,9.69 mg/kg respectively,at the sampling time of 1 h,6 h and 24 h.The value was reduced by 44.80%~57.87% and 42.52%~61.24%,respectively at 2nd day.The delayed release was transformed into negative release gradually with the frequency of sediment disturbance increase.Moreover,the value of DIP/TP and DTP/TP decreased gradually,too.It was indicated that sediment disturbance should promote the migration of dissolved phosphorus from overlying water to sediments and enhance the immobility of sedimentary phosphorus.All these resulted in the reduction of phosphorus availability.It was suggested that sediment disturbance could hinder the development of water eutrophication.