Converted Oil Platform Reef Sea Sediment Resuspension Of Phosphorus Adsorption - Desorption

Sediment-water interface adsorption and desorption of phosphorus is an important way to the transformation of phosphorus, it impact the concentration of the phosphorus in the water and the level of eutrophication directly. he artificial fish shelter and decommissioning oil platforms iron corrosion formed a unique sediment environment in Chengdao Oilfield. In this study, adsorption behaviors of phasphate on the surface sediments of Chengdao Oilfield in Bohai Sea were investigated, exploring the effects of resuspended sediments on phosphosrus fate. The influence of solid concentration of resuspended sediments, pH, and goethite content of the sediment on the adsorption-desorption of phasphate were simulated by batch experiments. The role of these factors infuencing the adsorption parameters, espacially adsorption capacity and EPCo, were mainly studied. The modified Langmuir, Freundlich and linear regression isotherm equation was used to fit the results of the experiments, and the role of computing EPCo was Compared. Finally, the law of adsorption was summarized by combining the survey result of the studied area and the experimental data. And the level of eutrophication was predicted by using the results of the study.The main conclusions are as follows:(1) The solid concentration increases, then the EPCo value increases, indicating a certain extent that the rise of the solid concentration was in favor of the release of the phosphorus in sediments. But the EPCo was still less than the value of the water phosphorus concentrations of the sea bottom, indicating that sediments performance of adsorption of phosphorus. Therefore, increasing of solids concentration owing to the construction of the project study area will not change the role of sediment phosphorus sink(2) The adsorption of phosphorus increased at the first and the decrease with the pH changing from6.5to8.5. The maximum adsorption capacity was appeared in the alkaline (pH value of7.71pm) condition. Small magnitude of the change in pH has little effect on the adsorption parameters, isothermal adsorption experiments showed that acidic or too alkaline will tend to make the phosphorus absorption, but this effect is very weak.(3) The increasing goethite content significantly affected the adsorption. The PAC and NAP increased with the increasing of the goethite content. It indicated that the the special surface of the goethite tended to fix the phosphorus in the water then the capacity of sediments of adsorption and desadsortion was enhanced in the meantime. EPC0slight decreaseed and Kp significantly increased, were explained as the sediments tednde to adsorb the phosphorus from the water.(4) By comparing the influence of the solid concentration, pH and goethite, combing with the space for the changes of the factors, we found that the solid concentration factor is the most important factor in the area of phosphorus adsorption and desorption. Under conditions of limited human and material resources, studies can be focused on the impact of solid concentration on the adsorption to capitalize on the trend as a whole.(5) EPC0analysis showed that the solids concentration remains the most important factor of phosphorus adsorption and desorption. The levels of goethite sediments can not EPC0obviously, but the goethite showed a degree of influence on EPC0. Fitting the data show that the modified Langmuir and Freundlich can be more reliable computing EPC0value, but the linear regression method had a larger deviation. Therefor the linear regression can not be used in calculating the EPC0in the study area.(6) Surveys showed that the phosphate and the solids concentration could changed synchronous.It indicated that the solid concentration was the important factor of phosphorus adsorption and desorption. Suspended sediments can absorb water phosphates being the sink of phosphate in the water. In the wholly, there was not a chance that the increasing of the solid concentration can cause the big increase of phosphorus concentration suddenly. But we does not rule out the solids concentration of phosphorus caused a significant increase of the phosphorus release on a extreme conditions. Retired Sea oil platform will not change the sediment environment and lead to phosphorus release cause eutrophication as a whole, but there may be high levels of local eutrophication.