The Research Of The Effect Of The Organic Matter In Sediments Of Dongchang Lake On Phosphorus Adsorption And Desorption Behavior

Lake eutrophication is a serious problem of water environment that countries inthe world are facing. In recent years, many lakes in China have also shown a trend ofdifferent degree of eutrophication, phosphorus as one of the limiting factors ofeutrophication has received extensive attention, the researches on phosphorusadsorption and desorption of sediment have increased.In order to study the effects of organic matter of lake sediment on phosphorusbehavior, we did some on-site investigation of Dongchang Lake and studied thevariation of organic matter and phosphorus in the lake during the replenishment, allthese helped us to have a more comprehensive understanding of the effect of organicmatter on phosphorus and so on. In order to further study the effect of the organicmatter on the behavior of the phosphorus, under laboratory conditions, we could getdifferent organic matter content of sediments treated by H2O2, we studied theadsorption thermodynamics and kinetics of the phosphorus of the sediments indifferent temperature, pH, dissolved organic matter (DOM) and organic matter underthe condition of the metal ion.The results are as follows:(1) In the replenishment of the Yellow River water to Dongchang Lake, while thecontent of total organic matter was high, the phosphorus was also high. The totalorganic matter was more complex organic and inorganic compound, it promoted thephosphorus adsorption of the lake. The phosphorus and organic matter content insediments of the lake district Ⅰ, Ⅲ was high than that of other lake districts, it wasnot only related with the sediment environment of the lake and the surroundingenvironment, but also was affected by the the Yellow River water. A large amount ofsuspended sediments were brough with the Yellow River replenishment, the suspended sediments could adsorb organic matter and phosphorus. The organic matterand phosphorus would settle to the bottom of the lake as the flow rate decreased. Theorganic matter in the sediment was one of the resource of the phosphorus and itmainly affect IP and NaOH-P of the sediment.(2) The desorption kinetics of the phosphrous of the sediment that was treated byH2O2were also divided into fast and slow desorption process. The desorption speedbefore the2h was higher. The release of the phosphrous of sediment with0.8%organic matter was larger than the sediment with1.2%organic matter, which meantthat the removal of the organic matter could promote the release of the phosphrous;different organic content of sediments in the experimental temperature (10℃,20℃,30℃) range, the amount of phosphate adsorption were increased with the increase oftemperature, showing that the phosphorus adsorption was an endothermic process.Different organic content of sediments in the test of pH (6,7,8,9) range, theadsorption amount decreased with the increase of pH. PH in neutral to acidic range,the phosphorus adsorption capacity was strong, and in the pH alkaline was waek.(3) The study of the effect of the dissolved organic matter on phosphorusbehavior showed that, DOM addition significantly changed the sediment adsorptionisotherms of phosphorus and phosphorus adsorption capacity increased with thecontent of DOM increased; the kinetics of phosphorus adsorption process of thesediment after the extraction of DOM were also divided into fast and slow desorptionprocess. The desorption speed before the2h was higher. For the extracted DOM itselfcontained a certain concentration of phosphorus, therefore, it might influence thedetermination of phosphorus, through the study, the relusts showed that, by adjustingthe pH to the strong acidic, the influence on the determination of phosphorus contentcould be eliminated.(4) The study of the effect of different organic matter content and metal ions onthe adsorption of phosphorus showed that, when the initial phosphorus concentrationwas1mg/L, the content of aluminum and iron were less than20mg/L and calciumwas less than100mg/L, phosphorus adsorption increased with the increasing oforganic matter and metal ions, the two factors adsorbed phosphorus in common. After that phosphorus was completely absorbed, phosphorus adsorption amount was notchanged despite the increase of the content of organic matter or the metal ion content,and the phosphorus adsorption strength of the three metal ions were nearly the same;when the initial phosphorus concentration was10mg/L, the phosphorus adsorptionshowed no obvious differences with the different organic matter content, while thephosphorus adsorption capacity increased with increase of the metal ion conten,which meant that in high phosphorus content, the metal ion played a main role onphosphorus adsorption, and the phosphorus adsorption amount of the metal ion was:aluminum>iron>calcium.