title: Volatilisation and competing processes computed for a pesticide applied to plants in a wind tunnel system.
abstract: BACKGROUND
  Volatilisation of pesticides from crop canopies can be an important emission pathway. In addition to pesticide properties, competing processes in the canopy and environmental conditions play a part. A computation model is being developed to simulate the processes, but only some of the input data can be obtained directly from the literature.
  
  
  RESULTS
  Three well-defined experiments on the volatilisation of radiolabelled parathion-methyl (as example compound) from plants in a wind tunnel system were simulated with the computation model. Missing parameter values were estimated by calibration against the experimental results. The resulting thickness of the air boundary layer, rate of plant penetation and rate of phototransformation were compared with a diversity of literature data. The sequence of importance of the canopy processes was: volatilisation > plant penetration > phototransformation.
  
  
  CONCLUSIONS
  Computer simulation of wind tunnel experiments, with radiolabelled pesticide sprayed on plants, yields values for the rate coefficients of processes at the plant surface. As some input data for simulations are not required in the framework of registration procedures, attempts to estimate missing parameter values on the basis of divergent experimental results have to be continued.
authors.affiliation: Alterra, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, The Netherlands. Minze.Leistra@wur.nl
authors.forename: Minze
authors.initials: M
authors.lastname: Leistra
authors.forename: André
authors.initials: A
authors.lastname: Wolters
authors.forename: Frederik
authors.initials: F
authors.lastname: van den Berg
mesh_terms: D003198:Computer Simulation; D007306:Insecticides / Q000737:chemistry*; D008956:Models, Chemical; D027805:Phaseolus; D013997:Time Factors; D014835:Volatilization; D014919:Wind
chemical_list: D007306:Insecticides