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河流水位变动会使部分床沙经历干燥再淹没,改变床沙吸附特性。本文选取淮河中游细颗粒床沙(<31μm),通过对比原始湿沙和风干沙的粒径和不同振荡强度下的磷吸附特性,探究考虑水动力条件下干燥再淹没对细颗粒床沙吸附特性的影响。结果表明,湿沙干燥后吸附能力下降,零净吸附磷浓度(EPC0)增大,易成为磷释放源。湿沙在干燥过程中会黏聚形成微团聚体,再淹没后起悬条件发生改变。随着水动力强度的增大,微团聚体会发生分散,使水沙接触面积增大,导致干湿泥沙不同动力条件下吸附特征差异显著。水动力强度和初始磷溶液浓度越低,干湿泥沙吸附特征差异越显著。水位变动改变了床沙对磷的吸附特征,是评估床沙对水环境调节作用的重要因素。
Changes in river water level will make part of the bed sand dry and then submerged to change the characteristics of bed sand adsorption. In this paper, we selected the fine bed of sediment (<31μm) in the middle reaches of the Huaihe River. By comparing the particle size of the original wet sand and air-dried sand and the phosphorus adsorption characteristics under different oscillation intensities, the adsorption properties of fine granular sand under consideration of hydrodynamic conditions Impact. The results showed that the adsorption capacity of wet sand decreased after drying, and the concentration of zero net adsorption phosphorus (EPC0) increased, which easily became a source of phosphorus release. Wet sand will stick together to form microaggregates during the drying process, and the suspended conditions will change after flooding. With the increase of hydrodynamic strength, microaggregates will disperse, increasing the contact area of water and sediment, resulting in significant differences in adsorption characteristics under different dynamic conditions. The lower the hydrodynamic strength and the initial concentration of phosphorus solution, the more significant the difference in adsorption characteristics between wet and dry sediment. The change of water level changes the adsorption characteristics of phosphorus in bed sediment, which is an important factor to evaluate the regulation effect of bed sand on water environment.