RESUMEN
A validation exercise of the SoilFug model using field runoff data from Rosemaund Farm (UK) is described. A comparison has been made of modelled and measured concentrations of several pesticides in surface water and soil during and after specific rain events following application. The field experiments were designed to obtain data on rainfall, outflows of water, pesticide application rates and concentrations in soil and water. The results were satisfactory for the undissociated pesticides (atrazine, carbofuran, dimethoate, isoproturon, lindane, simazine and trifluralin), whose concentrations in water were mostly predicted within an order of magnitude of measured data. The results for the dissociated pesticides (dichlorprop, MCPA, mecoprop) were less satisfactory, giving generally much higher predicted concentrations in water. The use of the SoilFug model is suggested for the calculation of predicted environmental concentrations (PECs) in water, since it generally produces acceptable results from a relatively small set of input data, most of which is generally available.
RESUMEN
Methods for measurement and estimation of octanol:water partition coefficients are discussed with particular reference to high values (log P greater than 5). A novel experimental method for P measurement is described and preliminary results presented. The use of high performance liquid chromatography capacity factors for estimating P values has been investigated; better correlations between the two parameters have been found if HPLC results at different methanol:water liquid phases are extrapolated to pure water, but even this procedure does not always give reliable P values. The interpretation of high log P values in terms of fish bioconcentration is discussed and the correlations of molecular connectivity and molecular weight with fish bioconcentration are presented.