Study On The Phosphorus Forms And Character Of Phosphorus Adsorption And Release In Sediment Of The Poyang Lake

Lake eutrophication is one of the most important environmental problems in ourcountry, the studies on phosphorus action in the interface of sediment-water is one ofthe key elements which helps find the mechanism of eutrophication. This paper,distribution character of phosphorus forms in the sediment was analyzed, andisotherm for phosphorus sorption and release onto superficial sediment of PoyangLake was studied under simulative condition.The TP content in sediment range from 456.98 to 991.71mg/kg,the channellocation influence distribution character of phosphorus forms in the sediment, the TPcontent in the entrance of lake is higher than other place. The IP was the majorphosphorus, and the Fe/Al-P were the major IP. The TP content is mainly under theinfluence of Fe/Al-P and OP, With the increase of TP content, Fe/Al-P percent in IPhad a increasing tend.In the condition of high initial P concentration, isotherms for P sorption ontosuperficial sediments of shallow lake accord with the Longmuir isotherm as well asthe Freundlich isotherm. There is the phosphorus desorption in the course of itsadsorptions on sediment. The phosphate adsorption isotherms on sediments fromlakes were fitted by linear model in low initial phosphorus concentration, andcalculate the phosphorus adsorption-desorption equilibrium concentration on sedmentfrom lake. It was higher than the critical concentration, the possibility of phosphorusrelease is high.The phosphorus adsorption was endothermic reaction, and temperatureascending was infavor of it in the sediment, but light contaminated one was moresensitive. The phosphorus adsorption in the sediment possessed particle concentrationeffect, it was more distinct in heavy contaminated sediment. The adsorption content atpH6 is more than at pH9. It shows that the sediments from heavy eutrophic lakeshave the trend to release phosphate into the overlying water.The article analysed the difference of phosphorus release between distilled waterand Poyang lake water, discussed the effects of environmental conditions (illumination,pH values,temperature,dissolved oxygen levels,microorganismand distortion) on the release experiment. The datum indicated that the maximumphosphorus released under illumination was smaller than that without illumination;Regression analyses of the maximum phosphorus released and pH values revealeda significant parabola relationship; the maximum phosphorus released were highlyand positively correlated to temperatures; Under oxic condition, the sediment canrelease phosphorus into the water, but the phosphorus levels and the releaseintensity were much smaller than those under anoxic condition; microorganism couldpromote the internal phosphorus release; The maximum phosphorus released understrong disturbtion was higher than that without be disturbed and the rate of releasewas high, there was no significant effect of weak disturbtion on phosphorus release.