Study On Release Of Nitrogen And Phosphorus From Water Level Fluctuation Zone In Three Gorge Reservoir And Its Control Techniques

The Three Gorges Reservoir is the largest water conservancy and control projects in the world. After the accomplishment of the project, a 30m-meter high water-level-fluctuating zone will appear which a seasonal humid ecosystem covering 291.1 km 2. This area will be both the sink and source of pollutants as the alternately dried and flooded conditions. A mass of pollutants containing P and N will deposit on the water-level-fluctuating zone, and then will be released into the water in inundation condition. The study on the effect of the adsorption and release of P and N in water-level-fluctuating zone of Three Gorge Reservoir is very important for water environmental protection of Three Gorge Reservoir.The release of P and N from typical soil in water level fluctuating zone of the Three Gorges Reservoir and the sediment from Jialing River were studied in this research. By conducting release and adsorption experiments of P and N under simulated inundation condition, release velocity and load of soil were confirmed. By conducting release experiments of NH4+ and P covered by zeolite and calcite.The study on the adsorption properties of soil with NH4+ and PO43- showed that NH4+ and PO43- could be absorbed by soil. The results indicated that the process of NH4+ and P in the area could be adequately described with Uniform-surface Langmuir equation. Alternately dried and flooded conditions had significant influence on the adsorption properties of soil. The adsorption capacity of NH4+ was increased from 666 mg/kg to 833 mg/kg, and the sorption capacity of P was increased from 256 mg/kg to 625 mg/kg. The EPC0 was increased from 0.46 mg/L to 1.47 mg/L. Alternately dried and flooded condition had significant influence on the desorption capacity of P which increased from 199~264mg/L to 274~334mg/kg, but the desorption ratio of P was decreased from 733.3~80.3% to 67.3~69.6%.The NH4+ and PO43- were released to the simulated water from soil which had adsorbed some of NH4+ and PO43-. The release capacity was larger as increasing the amount of NH4+ and PO43- absorbed by soil, and was affected by DO in the simulated water. The ratio of the release capacity of TN between aerobic and anaerobic condition was 1.2~1.4. The release capacity of TP in aerobic condition was larger than that in anaerobic condition.The influence on P release of alternately dried and flooded was not obvious in...