Study On The Biogeochemical Behavior And Control Of Nitrogen Pollutants In The Sediments Of Shifusi Reservoir

Shifosi reservoir is located in the main stream of liaohe river,which is also the only control project on the main stream.Due to the serious nitrogen pollution of surface water and underground water sources in liaohe river,how to prevent and control nitrogen pollution in shifosi reservoir and improve the efficiency of water treatment in water plant have become an urgent problem to be solved.Through the stone Buddha temple reservoir sediment research on nitrogen biogeochemical function,considering the sediment of various forms of N combined with concrete strength level and transformed the ability,and chose the continuous extraction to study the combined forms of N elements in the sediments and their distribution,through the indoor and the static and dynamic soil column experiment of ammonia nitrogen adsorption-desorption test the physical and chemical properties analysis and carries on the quantitative description,and pollution prevention and control of nitrogen in sediments.The specific research results are as follows(1)The hydrogeological situation of shifosi reservoir was analyzed.The meteorological,hydrologic and hydrogeological conditions of shifosi reservoir were investigated.(2)Water environment quality assessment.Using fuzzy comprehensive evaluation method to evaluate the reservoir surface water and groundwater,the results show that surface water is integral to ? class water,during altogether is better than that in dry season,the ammonia nitrogen biochemical oxygen demand exceeds bid badly;Groundwater ? class for the overall water,water as the main ? for water,individual ? class to water.(3)Study on the occurrence of nitrogen in the sediments of shifosi reservoir.This paper analyzes the existing form and distribution content of nitrogen in the sediments of shifosi reservoir and draws the following conclusions.The main form of nitrogen in sediments is organic nitrogen,and the total nitrogen content is between 12,280 and 23,700 mg/kg.The total convertible nitrogen content ranged from 1891.99 mg/kg to 10217.2 mg/kg,accounting for 38.24% to 43.92% of the total nitrogen.Due to the water supply in liaohe river,the water at the monitoring points in the reservoir had strong hydrodynamic forces,resulting in higher total nitrogen and total convertible nitrogen content in the sediments at the monitoring points 1,2 and 3 adjacent to the reservoir entrance.The water power in the inlet and outlet areas is weak and the nitrate and nitrogen content is relatively high.In sediments,ief-n is the form of nitrogen that is most easily released into water and contributes most to reservoirs.(4)Study on microbial community diversity of sediments in the reservoir area.In this study,the diversity of microbial communities in sediment was analyzed mainly by means of DNA extraction,PCR amplification and high-throughput sequencing.The results showed that the dominant species was proteobacteria with diverse microorganisms.Through the relative abundance analysis of functional annotation,it was found that nitrification,denitrification,chemical energy anomaly and nitrogen fixation of cyanobacteria existed in the diversity of microbial community,and the relative abundance was affected by dissolved oxygen,soil depth and hydrodynamic conditions.According to the analysis of multivariate statistical software,the dynamic change of microbial community in sediment in the reservoir area is strongly correlated with the change of environment due to dissolved oxygen and REDOX point.(5)Laboratory experiment on biogeochemical transformation process of nitrogen.In this dynamic test,the removal rate of ammonia nitrogen in the 0-40 cm deep soil layer was relatively high,and the maximum removal rate of ammonia nitrogen was 83.52%.In the static adsorption experiment,it can be found that the migration and transformation of sediment are related to the size of medium.There are two stages in both the adsorption and desorption processes,the rapid adsorption/desorption stage and the equilibrium stage.The rapid adsorption/desorption stage is because there are many easy adsorption/desorption points on the surface of the medium,and the pollutants can be attached/detached easily.The adsorption of ammonia nitrogen conforms to the nonlinear adsorption,and the adsorption-desorption thermodynamic process fits the Freundlich model best.The adsorption,desorption and rate of sediments are determined by particle size,effective mineral content and microbial community structure.(6)Study on nitrogen pollution control scheme at sediment-water interface of shifosi reservoir.The dissolved oxygen in the surface water can be increased by storing and releasing water in the reservoir,and the sediment can be regulated and analyzed by planting aquatic plants,so as to improve the surface water environment.The coupling model of surface water supply system and groundwater supply system was established,and the modified solute transport model and water flow model were used to predict and simulate the inflow concentration of liaohe river at the source of reservoir area,so as to protect groundwater and prevent and control the pollution of groundwater environment.