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RATE-LIMITED TRANSPORT OF HYDROXYATRAZINE IN AN UNSATURATED SOIL. (R824772)
Citation:
Kauffman, S. J., C. H. Bolster, G. M. Hornberger, J. S. Herman, AND A. L. Mills. RATE-LIMITED TRANSPORT OF HYDROXYATRAZINE IN AN UNSATURATED SOIL. (R824772). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 32:3137-3141, (1998).
Description:
Unsaturated column experiments on an intact soil core were conducted under
two different soil pressure heads, -8 and -19 cm, to characterize chemical
sorption and desorption for hydroxyatrazine. Breakthrough curves for
3H2O were similar under the different experimental
conditions. The advection-dispersion transport model described
3H2O transport well with Peclet numbers of 0.17 and 0.21,
respectively. The transport of hydroxyatrazine, a common degradation product of
atrazine, was slightly enhanced at the -8 cm head relative to the -19 cm head
(84% vs 79% mass recovery). A model that describes sorption with a single rate
coefficient and desorption as a distribution of rate coefficients fits the
hydroxyatrazine breakthrough curve well. The strong similarities in transport
properties at different soil-water tensions suggests that water and contaminants
can be transported through macroporous soils across a range of moisture
conditions in the vadose zone in agricultural fields.