Sediment Phosphorus Transformation Mechanism Under Different Disturbances

The Transform of Phosphorus in the water is a very worthy of study.now,in the process of constructing the theoretical system of phosphorus migration and transformation in shallow lakes,there are many key scientific problems waiting to solve.The previous studies mainly focused on the change of phosphorus concentration in overlying water and neglected the effect of sediment interface on Phosphorus Transform.It can only solve the scientific problem of the change of phosphorus forms in overlying water.But in fact the physical or benthic disturbance can change the micro environment and the micro interface in the horizontal or vertical direction.Such a change may have an important effect on the transformation of phosphorus in sediments.Therefore,it is necessary to further study the scientific rule of the phosphorus how to transform in the sediment.This paper studies the problem from two aspects.Under the condition of the presence of endogenous phosphorus,the study focused on the lateral variation of sediment environment and phosphorus forms under different disturbance and combined with the study of overlying water.Then,the dynamic change process of phosphorus in the sediment and the migration process of phosphorus in the overlying water were studied longitudinally under different disturbance conditions.The mechanism of phosphorus migration and transformation in sediments under different sediment disturbance was taken as the breakthrough point to reveal the scientific problems of regeneration and transformation of endogenous phosphorus with comprehensive analysis of phosphorus and combination of phosphorus in sediments.It is beneficial to improve the system of phosphorus migration and transformation.It can provide a theoretical basis for the further study on the mechanism and prevention strategy of eutrophication in shallow lakes.The results show that Combined disturbance with Corbicula fluminea will further increase the pH of the sediment.The extent of the impact on the pH extends to the depth of 20~30mm.And the addition of Corbicula fluminea and algae will lead to the further expansion of the sediment pH.The dissolved oxygen content in the overlying water and sediment decreases with the increase of disturbance factors.The appearance of Corbicula fluminea increases the trend of endogenous phosphorus release which resulting in the significant increase of different forms of phosphorus in overlying water(Some of the phosphorus may be derived from the excretion of Corbicula fluminea).However,the induction of endogenous phosphorus release by algae was more lasting.The decrease of DIP content in the interstitial water proved this point.With the increase of disturbance factors.The increase of endogenous phosphorus releases and transformaiton ratio from NH4Cl-P to Fe/Al-P also increases gradually.The main reason for the increase of the release rate of endogenous phosphorus is the introduction of water to the water,the consumption of dissolved oxygen and the increase of pH.Under the input of exogenous phosphorus,physical disturbance can further reduce the content of various forms of phosphorus in the overlying water.The biological disturbance and the combined disturbance are the opposite.Physical disturbance can reduce the content of DIP in the interstitial water,but the degree of reduction is not as high as that of the Chironomus plumosus and the combined disturbance group.Three kinds of disturbance can promote Fe/Al-P formation.Physical disturbance has the largest amount of Fe/Al-P average formation quantity.Three kinds of disturbance are conducive to the formation of Ca-P.But the greatest role is physical disturbance.The AAP of physical disturbance group has been reduced significantly which indicating the physical disturbance transforms from the AAP to Fe/Al-P or Ca-P transformation.And the Chironomus plumosus and combined disturbance can also promote the transformation of AAP to O-P in a certain extent.