Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/27/2001
Publication Date: N/A
Technical Abstract: Sorption-desorption of two sulfonylaminocarbonyltriazolinone herbicides and a phenylsulfamide and a triazole metabolite were characterized in clay loam and loamy sand soils. Sorption fit the Freundlich equation with sorption minimally concentration dependent (sorption isotherm slopes, 1/nf-sorb = 0.90-1.02). Sorption was much lower in the loamy sand than in the clay loam mdue to the lower clay and organic carbon contents. Average Koc = 60 for al chemicals on both soils, which is typical of sulfonylurea-like herbicides at the pH of the soils used, i.e. 6.2-6.7; sorption of sulfonylurea herbicides is pH dependent. Desorption of all chemicals was hysteretic. For the loamy sand, the chemicals did not desorb, desorption isotherm slopes, 1/nf-des = 0; while for the clay loam, the chemicals did not readily desorb, 1/nf-des = 0.13-0.61. Use of a single sorption coefficient would over predict potential leaching of these chemicals in soils, since sorption nis pH dependent and desorption is hysteretic.