he desorption rate is low.Through the experimental results of different reduction conditions impact on the nitrogen adsorption process , conclusion that under the conditions of Eh: -375 -150mv, pH: 7 10 ,the stronger of the solution reduction, the higher of its adsorption capacity and adsorption rate.2 Through static conversion experiment, determing nitrification, denitrification transformation process, conversion rate, conversion mechanism, transforming dynamic equations of nitrogen when does not change the reducibility conditions of solution. Determing conversion trend, conversion rate, conversion mechanism of nitrogen when change the reducibility conditions of solution. The results of this part show that: the nitrification and denitrification rate in the clay is rapid, 90 percent of the response is completed in 6 days. In the environment of Eh for 100-300mv, pH for 9-10, nitrification rate constant is less than denitrification rate constant, that is, this conditions is more conducive to the conduct of denitrification. Through the experimental results of different reducibility conditions on the nitrogen transformation process, obtained in the environment of Eh between -375-150mv,enhance the Solution reduction can reduce the nitrogen pollution in groundwater.3 Through dynamic soil column experiments,revealing migration and transformation mechanism of nitrogen pollutants in the saturated clay at the time of occurring vertical migration ,through experiments,determing oxidation-reduction,infiltration height,with the ion on the impact of nitrogen concentration when pollutants through Saturated clay layer.The results of this part show that: The more thicker of the layer, the more stronger of it’s blocking ability on ammonia.Before ammonia penetrate the clay layer,the interception rate is more than 90%.When nitrogen migrate in the saturated clay layer,the main action is adsorption, nitrification. denitrification accounted for a small part. Clay adsorption for ammonia mainly concerned with the cation exchange. Ca2+, Mg2+ concentration is the main factors for adsorption. We divide the chemical transformation of ammonia in the clay into three stages: (1) Weak period of nitrification, leaching time for 1-10 days, at this stage, the effluent nitrate concentration is low, pH is low. (2)Strong period of nitrification, leaching time for 10-20 days, at this stage, the effluent nitrate concentrations is high, H + increased, the effluent pH decreased.(3)Denitrification period , 20 days later, at this stage, the effluent nitrate concentration reduced again, this process will produce a large number of OH-, the effluent pH increased. The change and intensity of this three-stage are impacted by several factors. (1)dissolved oxygen. (2)soil and solution pH, Eh. Through the measure of retardation factor and water chemistry transport parameters of NH4+-N, NO3--N,NO2--N in the clay, conclusion that:With the increasing of clay thickness, the retardation factor of NH4+-N,NO3--N,NO2--N will be increased.That is, the more thick of layer,the block capacity of NH4+-N, NO3--N,NO2--N is greater .And the barrier capable of clay on NH4+-N is stronger than NO3--N,NO2--N. The water chemistry transport parameters of NH4+-N, NO3--N,NO2--N decreased with the increasing of height,that is, the more thick of layers, the more slow of NH4+-N, NO3--N,NO2--N. And soil thickness has little effect on the migration of NO3--N,NO2--N,but has a great impact.on the migration of NH4+-N.4 Establishing transport model of nitrogen in the saturated clay layer. The results show that :The migration process of NH4+-N and nitrogen in the saturated clay layer are in line with the one-dimensional mathematical model. So, we can use the model to predict the concentration trends of nitrogen when it occurring vertical migration in the saturated clay layer .
【关键词】 氮; 饱和粘土层; 迁移规律
【Key words】 nitrogen; saturated clay layer; migration law
氮污染物通过饱和粘性土
