Effect Of The Tidal Flat Sediment In Changjiang Estuary Wetland On The Content Of Nitrogen And Phosphorus In Water

This paper took tidal flat sediments in Yangtze River Estuary wetland and nitrogen & phosphorus in water as study object then it was simulated in the laboratory of reciprocity between the sediments and content of nitrogen & phosphorus in overlying water and then the interact character of nitrogen & phosphorus in the sediments leachate and pollutant load was simulated, too.During the experiment of reciprocity between the sediments and nitrogen & phosphorus in overlying water, the main factors that influenced on the removal efficiency of nitrogen & phosphorus, such as sediment, pollutant load, hydraulic capacity, detention time, etal, were studied and the release of nitrogen & phosphorus from sediments to the overlying water when the concentration was much lower in the inputting water, was studied, too, and then the purifying mechanism, removal ability of the sediments and some facts that affected on the purification, such as, detention time, temperature, etal, were discussed, too.During the experiment of the interact character of nitrogen & phosphorus in the sediment leachate and pollutant load, the effects of sediments, pollutant load, runtime, etal, on the nitrogen & phosphorus in the leachate were studied, and at the same time, the difference of remove efficiency of nitrogen & phosphorus by different sediments and the removal efficiency of the same sediment to the overlying water and leachate were discussed, too.The major results drew on this studies are:6.1 Removal efficiency of different sediments to the content of nitrogen & phosphorus in overlying waterwhen sewage was put in, All the sediments had high removal efficiency to the total phosphorus and for different sediments, the removal efficiency was not the same, while for inorganic phosphorus, the removal efficiency was far lower than the total phosphorus and it was widely different between sediments, but for nitrogen, when sewage was put in, the removal efficiency of different sediments for TN was different and very low.6.2 Effects of pollutant load, hydraulic capacity, detention time, on the nitrogen& phosphorus content in overlying water for the same sedimentPollutant load exerted an important influence on nitrogen & phosphorus in overlying water. In certain rang, as pollutant load increased, the removal efficiency for ammonia & total phosphorus increased, too, but the removal efficiency for ammonia & total phosphorus in the overlying water was not limitless, because when the concentration was too thick, the removal efficiency would drop instead. The removal efficiency and pollutant load followed different conic equations. In addition, the nitrogen & phosphorus of water just to be absorbed, precipitated and stayed in the surface of the sediment, if the concentration of phosphorus was low enough in the water body, some phosphorus would be released to water again from the sediment,take, the equalization point of release------absorb of the total phosphorus in the studyfor example, was about 0.469mg/L.Hydraulic capacity had the direct relation for removal efficiency of nitrogen & phosphorus in overlying water. With the increase of hydraulic capacity, removal efficiency was reduced rapidly, and then dropped slowly. The removal efficiency of total phosphorus & ammonia followed curve equation that decreased progressively when hydraulic capacity increased.Detention time also had the direct relation for removal efficiency of nitrogen &phosphorus in overlying water. The removal efficiency of phosphorus increased with the detention time became longer, but it was not proportional to the removal efficiency and the extension of time, while for ammonia, the removal efficiency just increase slightly when the detention time became longer, and the reduction of the ammonia was mainly caused by self-purification function of the water body with the time.6.3 Effects of different sediments on the content of nitrogen & phosphorus insediment leachateDifferent sediments would have a full impact on the remove efficiency of nitrogen & phosphorus in sediment leachate. The removal e...