Simultaneous Transport of Chloride and Water During Infiltration1
- C. Kirda,
- D. R. Nielsen and
- J. W. Biggar2
Displacement of chloride during infiltration was studied using soil columns for two cases: chloride initially spread on the soil surface; and chloride initially mixed with the soil. Chloride was applied as CaCl2 labeled with 36Cl. Its activity in counts per minute was scanned with a GM counter along a 2.5-cm wide window slit in the columns. In conjunction with the chloride activity measurement, gamma-ray attenuation measurement was used for monitoring the water content distribution during the simultaneous flow of chloride and water. Treatments included different levels of initial soil water content and different levels of water saturation at the soil surface during infiltration. With a numerical method the equations describing vertical water flow and miscible displacement of chloride were solved simultaneously. Experimental and calculated chloride distributions were in agreement. Chloride apparent diffusion coefficients estimated for pore water velocities less than 0.01 cm min-1 were nearly equal to that for moleculer diffusion only. Initial soil water content did not influence the depth of chloride displacement for a given quantity of water infiltrated; whereas, keeping the water content at the soil surface below saturation resulted in a deeper and more complete displacement of chloride.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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