Agricultural Nonpoint Source Pollution In Drainage Ditches In Migration Studies

Based on autonomous region of ningxia qingtongxia irrigation area as an example, thispaper choose typical drainage ditches qingtongxia irrigation district agricultural non-pointsource pollution in typical experimental zone, in2009conducted a drainage ditchagricultural nonpoint source pollution monitoring tests, the typical drainage ditches in thenitrogen and phosphorus nonpoint source pollutants has carried on the system such asmonitoring test, based on the detailed monitoring of the test data, analyzes the migrationcharacteristics of nitrogen and phosphorus pollutants in the drainage system; Canal bottomsediment in water was studied, adsorption, interception of agricultural nonpoint sourcepollution at the same time studies the effect on the absorption and transformation ofpollutants in aquatic plants, and applied to the field and indoor experiment the method ofcombining drainage ditches in the agricultural non-point source pollutants in the water-sediment-aquatic plant system migration of main influence factors and influence degree,combined with the interception of farmland drainage ditch on nitrogen and phosphoruspollutants removal effect, built a mathematical model of a preliminary description ofdrainage ditches in the transformation of agricultural non-point source pollutants migrationcharacteristics; And is applied to model the first drain (belonging to qingtongxia irrigationarea). The main conclusions of this study can be summarized as follows:(1) the drainage ditches for interception of agricultural nonpoint source pollution hasobvious effect, the interception of the ammonia nitrogen effect is best, intercept the least effect of nitrate nitrogen.(2) the concentration of nitrogen and phosphorus pollutants at all levels is a step-downtrend in drainage ditches, te6on the interception of nitrogen and phosphorus pollutantsremoval efficiency significantly superior to the dry ditch.(3) the existence of the aquatic plants can enhance the drainage ditch on nitrogen andphosphorus pollutants of intercept effect.(4) the aquatic plants can promote transfer of nitrogen, phosphorus, absorption ofnon-point source nitrogen and phosphorus pollutants can also be itself. Calamus onphosphate absorption is relatively obvious.(5) Ammonia nitrogen adsorption and nitration of interception is the result of joint action.Ditch Sediment nitrification relative adsorption effect was weak, but the change as timeincreases the nitrification. Ditch Sediment on phosphorus retention is mainly on solublephosphorus adsorption, with “fast adsorption, slow balance" characteristic.(6)In the realization of canals in the nitrogen, phosphorus pollutants maximum retentionrate, in other condition (aquatic plant species, density, the canal bottom sedimentproperties and so on) under the condition of the same flow rate and depth, plays animportant role, effect of the highest degree.(7) To the upper reaches of the Yellow River Qingtongxia irrigation area the first drainditch system as a typical case, based on water dynamics and pollutant migration anddiffusion equation, considering different drainage ditch water pollution transport in specificcircumstances, constructs the agricultural non point source pollutants in drainage ditches inthe migration model. Simulation results and measured data well combined, and has betterapplication effect.