ARS | Publication request: Interpreting kinetic data during adapted degradation

Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2012
Publication Date: N/A

Technical Abstract: Dissipation/degradation are fundamental processes governing pesticide environmental fate. It has become standard practice to describe rates using single first-order kinetic equations (SFO). In SFO the time for a decrease of a certain fraction of the compound remains constant; thus dissipation rate data can be conveniently described by the compound’s soil half-life (t1/2). SFO equations are simple to use, inherently conservative, and are used almost exclusively in regulatory pesticide assessments. However there are numerous published studies which demonstrate that SFO may not be the most appropriate kinetic model to describe pesticide dissipation kinetics. In this presentation, we will describe some of our experiences in using SFO and alternate models. Model use when adapted degradation conditions develop in soils will be highlighted. In almost all cases biphasic models that incorporate dissipation rates that change with time provide better fits to the data.