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Aquitard nitrate Factors Influencing Migration and Transformation

Author: XieXue
Tutor: LiXuQian
School: Jilin University
Course: Environmental Engineering
Keywords: Nitrate Aquitard Migration and Transformation
CLC: X52
Type: Master's thesis
Year: 2011
Downloads: 95
Quote: 1
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Abstract

With the rapid development of modern industry, emissions are growing increase in the surface water and groundwater generally subject to more severe pollution, water quality deterioration can not reach the standard. People's living standards improve and encourage people to higher demands on water quality and quantity, resulting in shortage of water resources has become increasingly serious. As has been severely polluted groundwater unfit mining, deep water, the water level dropped due to excessive exploitation, forming a groundwater drawdown funnel, so that poor water quality of shallow groundwater flow through the aquitard more deep groundwater recharge, resulting in a deep deterioration of groundwater quality. This paper supported by the National Natural Science Foundation, based on domestic and international concern shallow groundwater nitrate migration through leaky aquitard hot deep groundwater contamination issues, simulation studies: Studies in natural conditions, under different pH conditions different Eh conditions as well as under conditions of different concentrations of sulfate nitrate migration through the aquitard transformation pathways as well as with other relevant interactions between anions; research aquitard interdiction capacities for nitrate and nitrate in aquitard layer transfer mechanism and hydrodynamic equations; build nitrate in aquitard migration model. Obtained the following conclusions: (1) to simulate natural conditions, nitrate migration through the aquitard transformation process with pH, Eh values, sulfates as well as with other relevant interactions between anions: nitrate obtained under different conditions salt through the aquitard law broadly similar, but slightly different. Study found that when the sulfate concentration as the impact factor is more conducive for nitrate aquitard interdiction, followed Eh effects and, finally, different pH effects; aquitard the conversion of nitrate to the denitrification pathway is Lord, there will be very few nitrate reduction to ammonia alienation effect; Under natural conditions, other related nitrate ions through the aquitard role is the same, but according to environmental characteristics (environmental indicators) are different, some degree of influence different. (2) Nitrate aquitard interdiction capabilities and blocking mechanism: Nitrate aquitard interdiction role is very strong, its interdiction capacity sizes: Different sulfate concentration conditions gt; different Eh conditions gt; different pH gt; natural attenuation; aquitard reason why the strong ability of nitrate interdiction There are several reasons: Because the pores aquitard dominated by micro pores, permeability coefficient is very small, while the aquitard density, therefore aquitard strong mechanical filtration; pores filled with bound water, micro pore ion interaction with solid surface enhanced; aquitard specific adsorption on Ca2 can not only change the soil surface The variable positive charge, the charge can also make constant positive charge increases colloids or negative charge decreases, so that the negative charge on the clay surface NO3-reduced electrostatic repulsion; clay lattice adsorbed Ca2 hydration of reduced viscosity grains near the water activity, so that water diffusivity decreases nitrate transport velocity also decreases, clay surface water layer of water viscosity, Ca2 formed near the positive charge in the clay layer, NO3-static gravity, but also to remain in nitrate in aquitard. At the same time there is also aquitard adsorption (adsorption synergy), this effect makes the existence of aquitard nitrate adsorption capacity increases for yet another mechanism. (3) establishment of nitrate in aquitard in migration models: the establishment of nitrate in aquitard migration simulation model, based on experimental data obtained to estimate the model parameters obtained through mathematical transformation model analytical solution of nitric acid aquitard salt in the migration simulation. The process described by the model and parameter interception aquitard Nitrate attenuation effects on its primary role, followed by biological action. Simulation results and experimental results are consistent with the simulated groundwater conditions, nitrate can predict changes in the aquitard. Through the above research reveals a more comprehensive system of nitrate in aquitard in the migration and transformation and concentration variation, in order to prevent deep groundwater nitrate pollution and the protection and restoration of deep groundwater environment provides a theoretical basis and foundation.

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