水动力作用下泥沙对磷的吸附特征

为了研究水动力作用下泥沙对磷的吸附规律,在加长型环形水槽中进行不同流速、初始磷质量浓度及含沙量条件下泥沙对磷的吸附以及磷在水深方向的分布规律试验。结果表明,加长型环形水槽内试验段流速的垂向分布满足对数规律。溶解性活性磷酸盐质量浓度在水深方向非均匀分布,中部水深处磷质量浓度达到最大值。流速影响下的吸附规律取决于水相磷质量浓度:磷质量浓度较低时,流速越大对应的单位泥沙吸附量越小;磷质量浓度较高时,流速越大对应的吸附量就越大。泥沙质量浓度越小,初始磷质量浓度越大,单位质量泥沙对磷的吸附量越大。一阶、二阶动力学方程能够更好地表征淮河泥沙的吸附行为。伴随着泥沙沉降,水体磷质量浓度先增大、后降低,且在沉降0.25 h达到最大值。

Characteristics of adsorption of phosphorus by sediment under hydrodynamic action

In order to investigate the patterns of adsorption of phosphorus by sediment under different hydrodynamic actions,the adsorption of phosphorus and the vertical distribution of phosphorus were investigated through experiments in an elongated annular flume. The effects of velocity,initial phosphorus concentration,and sediment concentration were investigated. The results show that the vertical distribution of velocity in the elongated annular flume matched the logarithm law. The concentration of soluble reactive phosphate was distributed unevenly along the depth,and the maximum value appeared in the middle of the depth. The adsorption pattern of phosphorus under different velocity conditions depends on the mass concentration of soluble phosphorus. The amount of adsorption per unit mass of sediment decreased as the velocity increased when the phosphorus concentration was low,while it increased when the phosphorus concentration was high. The adsorption amount of phosphorus per unit mass of sediment increased as the sediment concentration decreased or the initial phosphorus concentration increased. The first- order and second-order dynamic equations can be used to describe the adsorption behavior of sediment in the Huaihe River. With the deposition of suspended sediment,the phosphorus concentration increased to a maximum at 0. 25 h and then decreased.