Volatilization of parathion and chlorothalonil from a potato crop simulated by the PEARL model.
The volatilization of pesticides from crop canopies in the field should be modeled within the context of evaluating environmental exposure. A model concept based on diffusion through a laminar air-boundary layer was incorporated into the PEARL model (pesticide emission assessment at regional and local scales) and used to simulate volatilization of the pesticides parathion and chlorothalonil from a potato crop in a field experiment. Rate coefficients for the competing processes of plant penetration, wash off, and phototransformation in the canopy had to be derived from a diversity of literature data. Cumulative volatilization of the moderately volatile parathion (31% of the dosage in 7.6 days) could be simulated after calibrating two input data derived for the related compound parathion-methyl. The less volatile and more slowly transformed chlorothalonil showed 5% volatilization in 7.6 days, which could be explained by the simulation. Simulated behavior of the pesticides in the crop canopy roughly corresponded to published data.
Leistra
Minze
M
Alterra, Wageningen University and Research Centre, Post Office Box 47, 6700 AA, Wageningen, The Netherlands. Minze.Leistra@wur.nl
van den Berg
Frederik
F
D003198:Computer Simulation; D018556:Crops, Agricultural / Q000737:chemistry*; D004058:Diffusion; D008956:Models, Chemical; D009570:Nitriles / Q000737:chemistry*; D010278:Parathion / Q000737:chemistry*; D010575:Pesticides / Q000737:chemistry*; D011198:Solanum tuberosum / Q000737:chemistry*; D013997:Time Factors; D014835:Volatilization
D009570:Nitriles; D010575:Pesticides; D010278:Parathion; C005806:tetrachloroisophthalonitrile