The Bohai Oil Production Platform Changed The Interaction Between Suspended Solids And Phosphate In The Reef Area

Sediment is an important medium about phosphorus cycle in natural water body and has important influence on the concentration of phosphate in aquatic environment.According to the survey,phosphorus is the limiting factor of eutrophication in Bohai sea,and phosphorus from external input has been effectively controlled,so the sediment interacts with overlying water will directly control the phosphorus concentration in the Bohai sea.Transformed oil production platform to fish reef will affect local water dynamic conditions and that likely affect the time of sediment contact with overlying water and solid concentration for the related areas.EPC0 is an important attribute of sediment,and it will determine the role(source or sink)of sediment in the water body.In this paper,we obtained EPC0 values of sediments by combining kinetic experiments and adsorption isothermal experiments.The effects of fluctuating kinetics of lower phosphorus concentration and solid concentration on the EPC0 of sediments were investigated.Sediment inorganic phosphorus sequential extraction was used to explore the reason of fluctuation dynamics.Main conclusions are as follows:(1)The kinetics curve of sediment react with high and low phosphate concentration were obvious different.Kinetic curve of high phosphorus concentration was monotonous and easy to reach equilibrium,but kinetics curve of low phosphorus concentration was fluctuant.The equilibrium time obtained by high phosphorus concentration kinetics experiment can not be used in the isotherm experiment.(2)Because of the phenomenon of fluctuant kinetic curve,choosing different incubation time in isotherm experiment will obtain a biased EPC0,then will be affect the judgment of sediment role in the natural environment.We should be used to select the experiment according to the practical situation of the reaction time and concentration of phosphorus.It is necessary to select the appropriate concentration and reaction time according to actual condition.(3)Fluctuation kinetic process of sediment reacts with low phosphorus concentration could be the result of mutual transformation between different forms of phosphorus in sediments.Iron and calcium in the sediment can promote the sediment adsorb phosphate.(4)The interaction of sediments with phosphate has a significant solid concentration effect.With the increase of solid concentration,the slope of isotherm decreases,the adsorption capacity of sediments and the buffering capacity of phosphates decrease.Sediment solid concentration and EPC0 value were positively correlated,but non-linear changes.(5)The order of different phosphorus forms content in sediments of Chengdao oilfield is HCl-P> BD-P> OH-P> loosely-P.Solid concentration effect has obviously influences in the process sediment phosphorus sequential fractionation.With the increase of solid concentration,the phosphorus content of each form decreased,and the percentage of each form will change.