Submitted to: Proceedings of the X Symposium of Pesticide Chemistry: Environmental Fate
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2007
Publication Date: 9/3/2007
Citation: Koskinen, W.C., Moorman, T.B., Anhalt, J.C., Papiernik, S.K., Cox, L. 2007. Characterization of imidacloprid availability in subsurface soils. Proceedings XIII Symposium in Pesticide Chemistry: Environmental Fate and Human Health. September 3-6, 2007, Piacenza, Italy. p. 88-91.
Technical Abstract: Degradation and sorption/desorption are the most important processes affecting the leaching of pesticides through soil because they control the amount of pesticide available for transport. Once pesticides move past the surface soil layers, variations in subsurface soil physical, chemical, and biological properties significantly affect pesticide fate and the potential for groundwater contamination. This research characterized the sorption-desorption of imidacloprid as a function of changing soil properties with depth in different soils. Sorption was highly variable, and desorption was hysteretic in all cases. Normalizing the sorption coefficients (Kf) to the organic carbon or the clay content of the soil did not reduce the variability in sorption coefficients for any compound. Data obtained suggest that imidacloprid was bioavailable to degrading soil microorganisms and sorption/desorption was not the limiting factor for biodegradation. It appears that differences in degrading populations may be the limiting factor for degradation. These results illustrate the importance of evaluation of the degradation and sorption data used to predict potential mobility. Understanding the variability of soil properties and processes as a function of soil depth is necessary for accurate prediction of pesticide dissipation.