Tool to determine the coefficient of variation of DegT50 of plant protection products in water-sediment systems for different values of the sorption coefficient

Samenvatting

In the present Dutch registration procedure and the EU procedure for inclusion of pesticides in a positive Community list of pesticide substances ( Annex1 ; Directive 91/414) inverse modeling of water-sediment experiments is used to estimate degradation rates in both the water layer and the sediment. However the original aim of a water-sediment experiment was to get a picture of the products formed for the pesticide and their persistence in water-sediment systems. Till now it is still unclear whether water-sediment experiments are suitable for estimating of the degradation half lives in the water layer and the sediment separately. This question was tested using simulations with a model describing pesticide behaviour in a water layer and its underlying sediment, in order to exclude experimental errors and peculiarities.