|Casey, Francis - IOWA STATE UNIVERSITY|
|Horton, Robert - IOWA STATE UNIVERSITY|
Submitted to: Geological Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 2, 1996
Publication Date: N/A
Technical Abstract: Groundwater contamination concerns have led to the development of solute transport mathematical models such as the mobile/immobile model. Using a tension infiltrometer and a sequence of conservative anionic tracers, an in situ method for determining the immobile water fraction and the mass exchange coefficient of the mobile/immobile model has been developed. This method offers an advantage to previous methods, because it measures actual field conditions and it is done without lengthy breakthrough curve experiments. Forty-seven measurement using four sequentially applied fluorbenzoate tracers took place along a transect. The tracers were applied through a tension infiltrometer at a -3 cm pressure head. Calculated immobile water fraction ranged from 0.288 to 0.952 and averaged 0.618 (+/- 0.148); while the mass exchange coefficient ranged from 0.000236 to 0.0112 min**-1 and averaged 0.00163 (+/- 0.00161). The distribution of these values along the transect did not appear to follow any trend. However, these values compare well with values reported earlier by other investigators.