The Study On The Effect Of Migration And Transformation Of Soil Nitrogen On Shallow Groundwater Under Freezing And Thawing

Freezing and thawing cycle phenomenon is a kind of common phenomenon in high latitudeor high mountain areas that soil temperature near the freezing point constantly fluctuating causessoil freezing and thawing, which influences on the soil structure, nutrients and microbialcommunities has been recognized by domestic and foreign researchers. With nitrogen as theimportant nutrients in soil, its form and in the soil after freezing and thawing distribution changelaw, occupies the freeze-thaw cycle research on the influence of the soil and the important position,the research is very rich. Groundwater is an important water resources in the production of humansociety can’t being ignored. Then due to agricultural production in the unreasonable use offertiliser and low fertilizer itself to the characteristics of the absorbed by crops, deterioration ofgroundwater quality caused great harm and potential risks. Of n and at present about the influenceof the groundwater quality research mainly focuses on crop growth period (mainly for the end ofMarch to the end of November), and the soil nitrogen on winter break is lack of research on theinfluence of the groundwater quality. For the study of freezing and thawing conditions betweenthe soil and shallow groundwater, ammonium nitrogen, nitrate nitrogen, interaction mechanism,simulation and evaluation of freeze-thaw cycles on the contribution of ammonium nitrogen andnitrate nitrogen in the groundwater provides theoretical basis for this article, through laboratorysimulation of freezing and thawing cycle conditions, different freezing and thawing cycleconditions, two typical northeast soil, ammonium nitrogen and nitrate nitrogen in soil, adsorption,desorption of echo vertical migration behavior, explore its migration may be the effects on thegroundwater quality in the process.The main research content mainly includes the following three parts:The paddy fields, corn field come from Chang Chun city Shuangyang District Hei Ding zireservoir downstream, as the research object. Different number of freeze-thaw test, the two kindsof dynamic response rules of soil ammonium nitrogen, nitrate nitrogen. Under the freezing andthawing, the nitrate and ammonium are significantly increased. And the biggest change occursafter first FTC. Ammonium transformation: dry field is generally greater than the the transitions ammonium in the paddy field, the paddy field and dry field ammonium nitrogen amount of thetransformation are decreased with the increase of depth. Nitrate transformation: paddy field: thetransformation of nitrate content increased with the increase of depth, and provided the initial valueand transformation of nitrate nitrogen amount increases with the depth. Visible, the freeze-thawcycle effect affects the transformation of soil nitrate, ammonium, and the influence degree isclosely related to the soil types and soil depth.Experimental simulation under different freezing and thawing conditions, detection indifferent stages of freezing and thawing soil adsorption ability of ammonium nitrogen, nitratenitrogen, the change rule of discusses two kinds of soil ammonium nitrogen, nitrate nitrogenadsorption isotherm. Research shows that, during the freezing and thawing soil and ammonium,nitrate adsorption isotherm was not significant difference. In different depth of soil, the adsorptionof ammonium nitrogen and nitrate is not significant. The retardation factor of nitrate, ammoniumchanged little in soil.The experimental simulation in different stages of the freeze-thaw cycle of the distribution ofsoil moisture, detecting the change of soil structure and the change of the infiltration of water.Freeze-thaw action will cause the soil moisture content to present S distribution. The permeabilityincreased significantly. This is mainly due to the pore structure in the soil deformation, the largerpore size and the redistribution of pore after freezing and thawing cycle, in both paddy field anddry field. The concentration of ammonium nitrogen and nitrate nitrogen in the exudate on theconcentration of the whole to be slightly lower than the control group the concentration of theexudate, but the down flux of ammonium nitrogen, nitrate nitrogen are about180%higher thancontrol group in total. These suggests that the freeze-thaw action will increase the risk that soilrelease the nitrate nitrogen and ammonium nitrogen to groundwater.