Modelling pesticide transport with a three-site sorption sub-model: a field test.
AbstractField measurements of the behaviour of the nematicide ethoprophos in the winter half-year were used to test a previously developed transport model in three soil types. In the model, the liquid phase is assumed to be homogeneous. The sorption sites are divided into three classes: sorption at class-1 sites is continuously in equilibrium with the liquid phase, whereas sorption equilibration at class-2 and class-3 sites takes place at time scales of days and months, respectively. The model explained the field-measured transport of ethoprophos satisfactorily. The effect of ignoring the long-term sorption equilibration process (i.e. sorption at class-3 sites) on calculated concentration profiles was much smaller than that found in a study reported in the literature for the herbicide cyanazine in a loamy sand soil. It was shown that this difference was related to a difference in the transformation rate coefficient. (Abstract retrieved from CAB Abstracts by CABI’s permission)