title: Sorption-desorption of imidacloprid and its metabolites in soil and vadose zone materials.
abstract: Sorption-desorption is one of the most important processes affecting the leaching of pesticides through soil because it controls the amount of pesticide available for transport. Subsurface soil properties can significantly affect pesticide transport and the potential for groundwater contamination. This research characterized the sorption-desorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine) and three of its metabolites, 1-[(6-chloro-3-pyridinyl)methyl]-2-imidazolidinone (imidacloprid-urea), 1-[(6-chloro-3-pyridinyl)methyl]-4,5-dihydro-1H-imidazol-2-amine (imidacloprid-guanidine), and 1-[(6-chloro-3-pyridinyl)methyl]-1H-imidazol-2-amine (imidacloprid-guanidine-olefin), as a function of changing soil properties with depth in two profiles extending from the surface to a depth of 1.8 or 8 m. Sorption of each compound was highly variable and hysteretic in all cases. Normalizing the sorption coefficients (K(f)) to the organic carbon or the clay content of the soil did not reduce the variability in sorption coefficients for any compound. These results illustrate the importance of evaluation of the sorption data used to predict potential mobility. Understanding the variability of soil properties and processes as a function of depth is necessary for accurate prediction of pesticide dissipation.
authors.affiliation: North Central Soil Conservation Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Morris, MN 56267, USA. papiernik@morris.ars.usda.gov
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Papiernik
authors.forename: William C
authors.initials: WC
authors.lastname: Koskinen
authors.forename: Lucia
authors.initials: L
authors.lastname: Cox
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Rice
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Clay
authors.forename: Nancy R
authors.initials: NR
authors.lastname: Werdin-Pfisterer
authors.forename: Kristen A
authors.initials: KA
authors.lastname: Norberg
mesh_terms: D000327:Adsorption; D007093:Imidazoles / Q000737:chemistry* / Q000378:metabolism*; D007306:Insecticides / Q000737:chemistry* / Q000378:metabolism*; D000073943:Neonicotinoids; D009574:Nitro Compounds; D012987:Soil / Q000032:analysis*; D014876:Water Pollution
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D012987:Soil; C082359:imidacloprid