Study on Sediment Phosphorus Release Mechanism of the Environmental Impact in Dahekou Reservoir

LU Junping; MA Tailing; LIU Tingxi; ZHANG Xiaojing; ZHANG Wenrui

doi:10.3969/j.issn.1003-6504.2017.07.012

Abstract：The study aims at understanding the influence of the reservoir overlying water environment change on the intensity of sediment phosphorus release,clarifying the quantitative linear relationship between phosphorus release intensity and environmental factors,as well as providing scientific basis for the treatment of eutrophication in reservoir.Sediment samples were collected from Dahekou Reservior in August 2014,the mechanism of phosphorus release from sediment under different water temperature,pH,water power and dissolved oxygen environment was analyzed.The results showed that increase of temperature is conducive to the release of phosphorus from sediments.Under the conditions of 25 ℃,the average phosphorus release intensity was 30.04 mg/m2,which was 3.3 times of the phosphorus release intensity of 9.01 mg/m2 at 5 ℃.Strong acid or alkaline conditions were conducive to the release of sediment phosphorus,test period under alkaline conditions (pH=9.5) of sediment phosphorus release intensity are as 1.1 times and 1.9 times respectively as that under the strong acid condition (pH=5.5) and neutral conditions (pH=7.0).The perturbation can accelerate water interface exchange and promote the phosphorus release from sediment.Under high strength disturbance,the maximum sediment phosphorus release intensity is 25.18 mg/m2,3.8 times of static conditions.With the increase of dissolved oxygen,concentration of sediment phosphorus release intensity decreased.When DO is above 6.5 mg/L,the sediment phosphorus release shows "negative release".The sediment phosphorus release intensity fits well with quadratic function curve of environment factors such as temperature,pH and hydrodynamics,also fits well with the cubic function curve of dissolved oxygen.