Study Of Nitrogen Endowment And Existence Characteristic In The Water-Submerged Plant-Sediment System

In the greenhouse of the Chinese Research Academy of Environment Science, we studyed the nitrogen translation process of the water-submerged plant-sediment system with the paint hydrilla verticillat and samples of two different sediments and a general meadow cinnamon soil of Beijing city. Besides, under the waterlogged incubation conditions, the nitrogen mineralization of the sediments and soil were investigated with the method of the intermittent leaching and continuously waterlogged incubation. The main results are as follows:In the water-submerged plant-sediment system, the Eh values of overlying water and sediments reduced gradually;but the pH values ascended from 8 to 9 and 10;the movement of the dissolved oxygen related to the nourishment of the setting.The concentrations of the total nitrogen in the overlying and the interstitial water were falling basically, and in the order of HH>HK>TR. Ammonia nitrogen in the interstitial water were reduecing too, and the layers showed c>b>a. The ammonia nitrogen in the water was the mostly being statement in the inorganic nitrogen, and the nitrate nitrogen was in a quite small proportion.With the incubation the total nitrogen quantity and the absorbable nitrogen quantity were gradully hoisting. The absorbable nitrogen quantity was in the order of HK>HH>TR and the HK treatment was the greatest vegetal condition to the hydrilla verticillata. The hydrilla verticillata could absorb a majority of the dissolve nitrogen decreasing the nitrogen burthen in the overlying water.In the sediments the total nitrogen, the organic matter and the ammonia nitrogen were also gradually decreasing, furthermore the ammonia nitrogen was the main being statement in the inorganic nitrogen content with the nitrate nitrogen fluctuating in a lower content level. The fixed ammonium content was gradually ascending, but the resease was remarkable in the present.Under waterlogged incubation conditions, the nitrogen mineralization were investigatedwith the method of the intermittent leaching, besides their nitrogen mineralization parameters (K, n) and the prediction equation were gained. The results indicated that their mineralization potential was in the order: HH>TR>HK. The rates of the N mineralization before the 11 incubation day are promptly augmenting to the maximal, and then the rates are gradually falling, at the end of incubation theirs are close to zero. The flood tide of nitrogen mineralization rates of HH sediment appeared earlier than HK and TR. The flood tide of ammonium in the N mineralzation process appeared in the 11 day of leaching time, and the N mineralzation quantity gradually got into a windless state. The content of organic matter, the total nitrogen and the fixed ammonium in the different treatments and levels at the end of incubation were lessened.Besides the nitrogen mineralization was still investigated with the method of the continuous incubation. The N mineralization quantity was hoisting promptly to the peak value, and then theirs were depressing gradually, recurring to the initiative levels in the end. The flood tide of ammonium in the N mineralzation process of HH and HK appeared earlier than TR. The N mineralization maximal cumulation quantity of HH was further more than HK and TR. The content of organic matter, the total nitrogen and the fixed ammonium in the different treatments and levels were aslo lessened.