title: Influence of the isomerism on the sorption of imazamethabenz-methyl by soil.
abstract: The sorption of meta and para isomers of the herbicide imazamethabenz-methyl, methyl 6-[(RS)-4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl]-m- or p-toluate, by three soils and soil organic matter, was studied. Sorption isotherms conformed to the Freundlich equation. It was found that pH was the main factor influencing the adsorption in all of the systems. The highest level of sorption was measured on soils with low pH and high organic carbon content. Moreover, at low pH value, the soil rich in smectite clays, favoured the sorption of meta rather than para isomer. The higher affinity of clay surfaces for the meta isomer of the herbicide is due to the stabilization of the meta protonated form by resonance. At all pH values, the sorption on soil organic matter did not differ between two isomers.
authors.affiliation: Dipartimento di Agraria, Desertification Research Group (NRD), Università di Sassari, Viale Italia 39, 07100 Sassari, Italy.
authors.forename: Maria Vittoria
authors.initials: MV
authors.lastname: Pinna
authors.forename: Alba
authors.initials: A
authors.lastname: Pusino
mesh_terms: D000327:Adsorption; D006540:Herbicides / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry; D007536:Isomerism; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D006540:Herbicides; D007093:Imidazoles; D012987:Soil; D012989:Soil Pollutants