La. Gaston et Ma. Locke, ORGANIC-CHEMICALS IN THE ENVIRONEMNT - FLUOMETURON SORPTION AND TRANSPORT IN DUNDEE SOIL, Journal of environmental quality, 24(1), 1995, pp. 29-36
The mobility of a synthetic organic compound in soil is affected by de
gradation and sorption reactions. Sorption is often a nonequilibrium p
rocess, leading to greater mobility and increased potential for contam
ination of shallow groundwater. Accordingly, this study was undertaken
to examine sorption kinetics of the herbicide fluometuron [N,N-dimeth
yl-N'-[3-(trifluoromethyl)-phenyl]urea] in Dundee silty clay loam (fin
e-silty, mixed, thermic Aeric Ochraqualfs), a common soil in the Missi
ssippi Delta. Batch experiments indicated sorption equilibrium was ach
ieved by 72 h contact time. Other data suggested little degradation of
fluometuron within this time. The approach to equilibrium was charact
erized by an initially very rapid reaction, followed by a slower rate
of sorption. This behavior could be equally well described by either a
nonlinear two-site equilibrium/kinetic or equilibrium/diffusion model
. Reaction parameters determined from the batch experiments were furth
er validated by use in a transport model to predict fluometuron moveme
nt in this soil. Within parameter uncertainty, the two-site equilibriu
m/kinetic model gave accurate predictions of fluometuron mobility. Exp
licitly modeling time-dependent sorption as a diffusion process offere
d minor improvement in transport predictions.