title: Glyphosate and AMPA adsorption in soils: laboratory experiments and pedotransfer rules.
abstract: Adsorption of the herbicide glyphosate and its main metabolite AMPA (aminomethylphosphonic acid) was investigated on 17 different agricultural soils. Batch equilibration adsorption data are shown by Freundlich adsorption isotherms. Glyphosate adsorption is clearly affected by equilibration concentrations, but the nonlinear AMPA adsorption isotherms indicate saturation of the adsorption sites with increasing equilibrium concentrations. pHCaCl2 (i.e. experimental pH) is the major parameter governing glyphosate and AMPA adsorption in soils. However, considering pHCaCl2 values, available phosphate amount, and amorphous iron and aluminium oxide contents by using a nonlinear multiple regression equation, obtains the most accurate and powerful pedotransfer rule for predicting the adsorption constants for these two molecules. As amorphous iron and aluminium oxide contents in soil are not systematically determined, we also propose a pedotransfer rule with two variables-pHCaCl2 values and available phosphate amount-that remains acceptable for both molecules. Moreover, the use of the commonly measured pHwater or pHKCl values gives less accurate results compared to pHCaCl2 measurements. To our knowledge, this study is the first AMPA adsorption characterization for a significant number of temperate climate soils.
authors.affiliation: Bureau de Recherches Géologiques et Minières, BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060, Orléans Cedex 2, France.|Université de Lyon, UMR5023 Laboratoire Ecologie des Hydrosystèmes Naturels et Anthropisés, CNRS, ENTPE, Université Lyon 1, 3, rue Maurice, 69518, Vaulx-en-Velin, France.
authors.forename: Pauline
authors.initials: P
authors.lastname: Sidoli
authors.affiliation: Bureau de Recherches Géologiques et Minières, BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060, Orléans Cedex 2, France. n.baran@brgm.fr.
authors.forename: Nicole
authors.initials: N
authors.lastname: Baran
authors.affiliation: Université de Lyon, UMR5023 Laboratoire Ecologie des Hydrosystèmes Naturels et Anthropisés, CNRS, ENTPE, Université Lyon 1, 3, rue Maurice, 69518, Vaulx-en-Velin, France.
authors.forename: Rafael
authors.initials: R
authors.lastname: Angulo-Jaramillo
mesh_terms: D000327:Adsorption; D000383:Agriculture; D005998:Glycine / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D006540:Herbicides / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007555:Isoxazoles; D008956:Models, Chemical; D063065:Organophosphonates / Q000032:analysis* / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D013777:Tetrazoles; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D007555:Isoxazoles; D063065:Organophosphonates; D012987:Soil; D012989:Soil Pollutants; D013777:Tetrazoles; D000097797:Glyphosate; C418233:2-amino-3-(3-hydrox-5(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl)propionic acid
keywords: AMPA; Chromic cambisol; Glyphosate; Nonlinear multiple regression; Sorption