Interception And Removal Effection Of Agriculture Drainage Ditch On Nitrogen And Phosphorus

In order to effectively intercept and remove nitrogen and phosphorus of agricultural soil, the transfer and transformation of nitrogen and phosphorus and the interception effect of agriculture drainage ditch on nitrogen and phosphorous are studied on field experiment, and advanced research is carried out to reveal the mechanism of interception and removal of nitrogen and phosphorous in the micro-system of water-ditchsediment-macrophyte-microorganism by macrophyte, microorganism and ditch sediment on lab simulation experiment in the paper.The field result indicates that: 1 ) transference and transformation of nitrogen and phosphorus in agriculture drainage ditch and under rainfall and irrigation is very similar through simulating: NH₄⁺-N concentration variation is on the whole the descending variation of the exponential curve both along cross section and with time, and the correlation is good; the TN concentration variation on the whole is similar to that of NH₄⁺ -N; not only DTP concentration variation is on the whole the descending variation of the exponential curve both along cross section and with time, but also TP concentration variation is on the whole the descending variation of the exponential curve both along cross section and with time, furthermore, the correlation is very good. This indicates that transference and transformation of nitrogen and phosphorus in agriculture drainage ditch has intrinsic change rule, especially NH₄⁺-N, TN, DTP and TP. 2) Comparing to the pollutants concentration and inception rate of inlet and outlet under irrigation and rainfall, agriculture drainage ditch has good interception and removal effect.The result indicates that: 1) the caduuciflora and acorus calamus in the ditch can accelerate the interface exchange by which nitrogen and phosphorous of superjacent water is reduced and obviously speed up the intercept and the transfer and transformation of nitrogen and phosphorous. 2) Decomposition and transformation of microorganism on nitrogen and phosphorus is the main one way of removing pollutants. There are a mass of aerobic, anaerobic and facultative microorganism in ditch wetland. Aerobic bacteria decompose nitrogen, phosphorus and other organic matter to NO₃^-, PO₄^3-, SO₄^2- , which are taken in by macrophyte. Anaerobic microorganism, e.g. nitrate-reducing bacteria and ferment bacteria, decomposes organic matters into CO₂ NH₃ H₂S PH₃ CH₄, etc. which escape into atmosphere. 3) Since ditch sediment possesses tremendous surface area, large quantity of NH₄⁺-N and DTP are adsorbed. In the process, nitrogen and phosphorus is firstly adsorbed onto the particle of sediment, after certain quantity attain, nitrogen and phosphorus can reaches sediment clearance water through sediment surface. Which result in the concentration increase of NH₄⁺-N and DTP in sediment clearance water, and finally reached homeostasis. There is a great deal of microorganism in sediment, which can degrade much NH₄⁺-N. As for NO₃^--N, the change is not obvious under the condition that concentration is lower, within certain pH limits; the difference of pH has no marked effect on alternation of the concentration of nitrogen and phosphorus.Through the study on the transfer and transformation mechanism of nitrogen and phosphorus in agriculture drainage ditch, we can find agriculture drainage ditch can efficiently intercept and remove nitrogen and phosphorus. And this paper researches a new technology which can effectively intercept and remove nitrogen and phosphorus. It may provide valid scientific knowledge foundation and rightful administrative methods for the later nitrogen and phosphorus pollution regulation...