Seasonal Variation Characteristics Of Phosphorus Speciation In Eastern Water Source Areas Of Chaohu Lake And Simulation Study Of Microbial Effects

Lake eutrophication already has affected the production and life of coast residents.Phosphorus is a key factor leading to the eutrophication of Chaohu Lake. After years of control and governance,the point sources are gradually being controlled, and the agricultural non-point source pollution and internal source pollution become the main sources of phosphorus pollution in Chaohu Lake Basin. When various environmental factors influence internal phosphorus,such as temperature, DO and disturbance, phosphorus in the sediments can release and lead eutrophication.The character of phosphorus speciations were investigated,and possible sources were estimated We maked the simulation experiment of sediment bioavailable phosphorus release,and discuss the impact of microorganisms on the transformation process. The main work is in the following aspects:1.Speciations character and sources of phosphorus in the eastern water source areas and inflow rivers of Chaohu LakeThe overlying water is perennial slightly alkaline.The content of phosphorus of inflow rivers display seasonal variations obviously,high-water period higher than low-water period. The concentration of phosphorus of Shuangqiao river are higher than Zhegao River and XiaoZhegao River.Phosphorus concentration of water source areas display a similar seasonal variations influence by land. Concentration of phosphorus in the Lake District have a smaller change over time. The more recent from the lake district, the lower of the phosphorus contentThe main sources of phosphorus pollution of The Zhegao and XiaoZhegao River are agricultural water and domestic sewage. The Shuangqiao river is also affected by industrial waste water and solid waste,so water quality is poor. The three inflow rivers are subject to non-point source pollution. Therefore, rain has a great impact to water phosphorus concentrations. The phosphorus content of the high-water period is higher than the level of nornal-water period and low-water period. Comparing with phosphorus concentration of water in lake,the phosphorus concentration of water in inflow rivers are higher. Inflow rivers are the important sources of the phosphorus pollution in the lake. PP,which is the main form of phosphorus in water,mainly come from the non-point source pollution such as surface runoff and sewage. PP has a great impact on phosphorus of the water in the lake.2.Simulation study of bio-available phosphorus transportation and transformationThe simulation is based on the study of speciations character and sources analysis of phosphorus in the eastern water source areas of Chaohu Lake. Collect the sediments of western lake,and then conduct simulations. Variation of bio-available phosphorus speciations in overlying water and sediments are discussed under different environmental conditions (Temperature, DO,hydraulic disturbance and sterilization).The samples of overlying water and sediment display a slightly alkaline. TP is worse than V class water standard. PP is the main form. BAP of sediments show that AAP>WSP>OLP>RDP. Kinetic experiment shows:when the initial phosphorus concentration of the overlying water is0.05mg/L, sediment shows " source " features; when the initial phosphorus concentration is0.5mg/L, sediment shows " sinks " features.Under different environmental conditions, phosphorus concentrations in the overlying water of sterile system is significantly higher than bacteria system.TP concentration of the overlying water in the sterile system increases with increasing temperature.Bacteria system changes in the the opposite with sterile system,mainly to reduce the DIP.TP concentration of the overlying water in aerobic condition is higher than anaerobic condition.On the contrary,TDP concentration in anaerobic condition is higher. Disturbance makes TP significantly increase.there is a tendency that TP concentration increase with the increase of the frequency of disturbance.After the disturbance, PP increases, DIP and DOP reduce.The main reason is that the adsorption and flocculation of small suspended particles in water. Therefore, disturbance cause the release of the TP only, but not necessarily lead to the release of dissolved phosphate.Under different environmental conditions, phosphorus concentrations in the sediment of sterile system is significantly higher than bacteria system. BAP of sediments show that AAP>WSP>OLP>RDP.The influence of microbial effects on RDP and WSP is slight.And Temperature has a little influence on the WSP. AAP and OLP have the same change trend, presented a fluctuant condition. BAP of sediment in anaerobic condition is higher than aerobic condition. Sediment resuspension lead to Distribution and content change of BAP. Sediment resuspension can inhibit the AAP formation.When60r/min, the content of AAP is lower than control experiment obviously.But, BAP of sediment increase,when140r/min. The reason needs further study.3. Simulation experiment on bioavailable phosphorus conversion with microorganismsUnder different temperature conditions, humus-reducing bacteria's role of bioavailable phosphorus conversion on the water-sediment interface was discussed.BAP concentrations of the overlying water are promoted by humus-reducing bacteria. Sediment shows " source " features.When exist natural microflora in the system, phosphorus concentration of the overlying water is lower than initial concentration,even though humus-reducing bacteria promote phosphorus concentration rise. Sediment shows " sinks " features.By the action of humus-reducing bacteria alone, BAP concentrations of the overlying water are higher. Humus-reducing bacteria may decrease the phosphorus accumulating of the original microbial.Humus-reducing bacteria and natural microflora can promote the formation and accumulation of BAP. The contents of WSP,OLP and RDP are the maximum in the action of humus-reducing bacteria alone,except AAP. Humus-reducing bacteria has a little influence on WSP.When exist natural microflora in the system, Humus-reducing bacteria has a little influence on OLP. Humus-reducing bacteria can promote the formation of RDP,however, natural microflora decrease effect.BAP of sediment fluctuate quite a bit under60r/min. The contents of AAP increase and then decrease with the increase of the frequency of disturbance, as opposed to DIP.Humus-reducing bacteria can promote the formation of RDP and WSP.