持续水动力作用下湖泊底泥胶体态氮、磷的释放

为揭示水动力扰动及其后续沉淀效应对湖泊内源氮、磷营养盐释放的作用,通过室内试验模拟了水体在受到持续扰动后又长时间静置沉淀的整个过程. 结果表明,水动力扰动初期可引起底泥颗粒态和胶体态氮、磷向水体大量释放. 在连续扰动0.5 d时,水体总氮(TN)和总磷(TP)浓度分别达最高值2.106 mg/L和0.272 mg/L; 连续扰动1 d时,水体中胶体氮(CN)和胶体磷(CP)含量分别达最高值0.452 mg/L和0.052 mg/L; 之后虽继续扰动,因颗粒物和胶体物质的凝聚沉淀作用超过了其悬浮量,TN、TP、CN、CP的含量却转而降低.在停止扰动后的静置过程中,大颗粒悬浮物迅速沉淀,而胶体物质沉降缓慢,静置时间超过1 d后,CN和CP含量才开始因絮凝沉淀而降低.真溶解态氮(UDN) 和真溶解态磷(UDP)含量在扰动阶段升高较少而在静置1　d之后有持续大幅度升高,说明胶体的吸附作用在扰动阶段限制了水体溶解态氮磷含量的升高,且延长了其悬浮后在水柱中的停留时间,在扰动后的静置阶段,胶体又会将吸附的氮磷解吸释放到水体中,从而延缓了营养盐去除和水质的改善.

Release of Colloidal N and P from Sediment of Lake Caused by Continuing Hydrodynamic Disturbance

The course of continuing hydrodynamic disturbance and succeeding long time settlement of lake water was simulated to study the release of nitrogen(N) and phosphorus(P) from lake sediment. It was showed in the experiment that the hydrodynamic disturbance caused abundant release of particulate and colloidal phosphorus and nitrogen. The concentration of total nitrogen(TN) and total phosphorus(TP) in water reached the highest values of 2.106 mg/L and 0.272 mg/L,respectively,when the water was disturbed for 0.5 d, and the concentration of colloidal nitrogen(CN) and colloidal phosphorus(CP) in water reached the highest values of 0.452 mg/L and 0.052 mg/L, respectively, when the water was disturbed for 1 day. Then, the concentration of TN, TP, CN and CP turned to decrease despite the continuing disturbance, for the particles and colloid deposited exceeded that suspended. During the settling phase after disturbance, the bigger suspended particles deposited quickly while the tiny colloid deposited much slower, and the concentration of CN and CP did not decrease until the water was settled for 1 day. The concentration of ultra-filtrated dissolved nitrogen(UDN) and ultra-filtrated dissolved phosphorus(UDP) increased much more in the settling phase than in the disturbing phase. It can be drawn that the adsorption of colloid limited the increase of dissolved N and P in lake water in the disturbing phase and prolonged the time of suspended N and P stayed in water. And the N and P adsorbed by colloid could also be released into water in the settling phase after disturbance, which delayed the elimination of nutrition and improvement of water quality.