Volatilisation of pesticides from plants is one of the main pathways for their emission to the environment. A simplified computation model was set up to simulate this volatilisation, including penetration into plants and photochemical transformation as competing processes. Previous wind tunnel experiments using plants sprayed with C-14-labelled fenpropimorph were simulated using the model. Volatilisation could be simulated by diffusion through a laminar air-boundary layer, with a thickness in the range of 0.5-1.0 mm. Rate coefficients of 1.7-4.8 d(-1) had to be used to simulate the penetration of fenpropimorph into different plant species. The rate of phototransformation was lowest when the incoming air stream was filtered through activated carbon, thus minimising the formation of hydroxyl radicals by sunlight. The simulations enabled us to estimate model parameters that could neither be derived from laboratory studies nor could be obtained with pesticide (non-labelled) in the field.
|Journal||Water Air and Soil Pollution|
|Publication status||Published - 2004|