Simulation Study Of Nutrient Release From Water Fluctuating Zone In Miyun Reservoir

The South-to-North Water Diversion Project alleviated the shortage of water resources in the north.The water quantity of the reservoir,the water level rapidly and the variation area of the variation zone of the water level around the reservoir increased.The nutritional status of the reservoir was changed.Therefore,the Miyun reservoir was chosen as the object in this study.The soil samples of different elevation in the Miyun reservoir were collected,and the distribution of phosphorus forms was analyzed.the water level was changed to analyze the variation of nutrition elements's in simulated soil column experiments.The main work and research findings include:The content of Fe-P and Ca-P of sediments in the water phase of the Miyun reservoir are generally higher than that of terrestrial soil.The content of Ca and P in aqueous sediments were the highest.The MLOP in soil and sediment is the main component of organophosphorus.The content of total nitrogen,nitrate and ammonia in the soil of aqueous phase was significantly higher than that in terrestrial facies.The content of Mn,Fe and Al in continental soil were obviously higher than that in water phase.The deposition of Fe and Al in soil is mainly influenced by metal oxides,while the deposition of metal is not the main factor to influence the content of phosphorus.The soil column was used to simulate the dynamic change of flood and dry fall in the range of water level.In Column A's and column B's inundation experiments,they were found that the low content of NH₄Cl-P was easily released into the water during flooding.The change of aluminum-phosphorus content was contrary to that of iron and phosphorus.The contents of ammonia and nitrate increased in the early stage of flood.Because of the mineralization of ammonia oxidizing microorganisms and the decrease of dissolved oxygen,the contents of ammonia and nitrate nitrogen decreased rapidly.The total nitrogen content in continental soil increased with the increase of depth.The total nitrogen content in underwater sediments was higher than that in shore.In the dry experiment of column C and column D,the content of ammonia nitrogen and nitrate content increased,and the total nitrogen in the column A-D changed little.The experiment was carried out to simulate the constant water level of water level with soil column.The soil in the far bank can lead to the increase of stable organic phosphorus in the submerged state,while the stable organophosphorus in the deformation zone,under water and in the bottom tends to decrease.Therefore,in the process of reservoir flood,we should pay attention to the change of stable phosphorus in the surface of water and land,under water and underwater soil,and control the generation of plants in water.TN in water is mainly nitrate.In the time of 24 hours to 40 days,the accumulation rate of nitrate nitrogen was the highest in the nearshore and variable zone,and the lowest in the distal shore and bottom sediment.Therefore,in the process of water storage in reservoirs or lakes,TN and nitrates in the transfection zone,distant bank and shoreline area should be controlled to reduce the eutrophication of water bodies.