Modelling ethoprophos and bentazone fate in a sandy humic soil with primary pesticide fate model PRZM-2

Primary pesticide fate models an powerful tools for ranking pesticides with in an environmental contamination risk analysis context. The performance of primary pesticide root zone model PRZM-2 to analyse ethoprophos and bentaz one transport and dissipation is assessed. The evaluation was performed wit hin the framework of an European modelling validation exercise, which enabl ed us to use a high quality data set and to adopt a standardised modelling protocol. Within this paper PRZM-2 was evaluated by four different users us ing the Vredepeel data set. Simulations were carried out with and without c alibration of some parameters, as identified by the independent model users . Finally, a simulation with a consensus parameter set was performed. The model did not accurately describe the behaviour of ethoprophos and bent azone. However the model gave predictions of chemical concentration that we re within an order-of-magnitude. It is clear from this exercise that, given exactly the same data, different model users will parametrise a model in v ery different ways which in turn will lead to very different model output. Control of model input and guidance for the selection of inputs is therefor e vital if a model is to be used to predict the fate of pesticides in the e nvironment. (C) 2000 Elsevier Science B.V. All rights reserved.