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Solute transport in the boundary layer in the soil

Author: ZhengJiYong
Tutor: ShaoMingAn
School: Northwest University of Science and Technology
Course: Soil
Keywords: Solute transport Parameter Boundary layer method Colorings TDR
CLC: S153.5
Type: Master's thesis
Year: 2001
Downloads: 338
Quote: 1
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Abstract


Emissions of industrial waste, agricultural production, fertilizers, pesticide application, and radioactive substances underground buried lead to groundwater pollution, a serious threat to human life and health. Must understand in order to determine the degree of pollution hazards, contaminants in porous media migration law and predict the dynamic distribution, and therefore need to establish the mathematical model under a variety of conditions and the estimated model parameters. The boundary layer method for determining solute transport parameters convenient, but has not yet tested in the application of the feasibility study, and the the application boundary layer method to determine solute transport parameters, you first need to be addressed before a problem is how to determine the boundary layer position. According means of visualization and widely used tracer ion migration and undisturbed soil probe ion concentration changes, brilliant blue food dye and TDR appropriate as a means of tracing and detection solute front and boundary layer The method to determine the feasibility of the parameter in the practical application. The results show that: 1. Brilliant blue stain in the soil chemical reaction and adsorption and desorption law, and therefore application of the boundary layer staining method proceeds estimated solute transport parameters is much larger than Cl - transport parameters. Coloring agent in aqueous solution anion state exists, but, due to its special molecular structure, can still be soil adsorption boundary layer lagging movement in Cl - , thus stain does not accurately indicate Cl - boundary layer movement conditions. 2. Based on boundary layer theory, boundary layer depth and time was a significant linear correlation the dye instructions Cl - boundary layer also showed a significant linear relationship, so you can find out the stain indicated correct location of the boundary layer of the stain indicates the relationship that exists between the boundary layer Gl - and Cl - the actual boundary layer. Four soil samples, the precise location of the boundary layer of the revised stain indicated Cl - : Wind sand: d cl = 5.39d dve -6.12, bulk density as 1.30,1.25,1.20 g / cm 3 loess soil are: d cl = 9.96d dve -22.71; d cl = 9.41d dve -12.89; d cl = 5.51d (dve) -8.33. The position of the boundary layer of stain indicates correction, the position of the boundary layer that makes the use of dye instructions Cl - application boundary layer method to accurately determine the transport parameters of the Cl - becomes possible. 3. The change from TDR the probe solute Feng and concentration that the solute Feng did not reach the detection point of solute transport in the boundary layer method TDR-11-soil salinity displayed value is a constant value solute front arrives salinity values ??at the beginning and gradually increase in TDR probe concentration of the whole process of change and breakthrough curves are very similar, indicating that has TDR probe solute front. Better feasibility for using boundary layer method to determine the parameters of solute transport in a good means of monitoring solute front. 4. Instantaneous boundary layer method to determine solute transport parameters and breakthrough curves of the classic to be legally determined parameters were compared, both estimated hydrodynamic dispersion coefficient ①) very similar, but the transient boundary layer method to estimate the delay factor m) than The breakthrough curves obtained by fitting the R value is large, this may be due to the TDR determined boundary layer with respect to the actual boundary layer lag caused. 5. Instantaneous boundary layer within a certain time to predict the predicted density profile of the concentration profile with the exact method is basically the same, indicating that under certain conditions can make use of the boundary layer method for solute transport parameters estimated and can be used to predict pollutant in the soil profile Dynamic distribution. 6. The tiny flux boundary layer method is derived instantaneous pulse conditions under continuous input processing an input pulse inputs, take k = 0.0001 delay the R factor R with the breakthrough curve fitting method values ??are very close, and the proliferation of the diffusion coefficient D values ??larger difference. With assume the smaller of the values ??of k and D values ??obtained by this method becomes gradually smaller. Through computer simulations, it is found that the TDR probe boundary layer the lag D value smaller.

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CLC: > Agricultural Sciences > Agriculture as the foundation of science > Soil > Soil chemistry, soil physical and chemical > Soil solution
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