title: Effect of Soil Water Content on the Distribution of Diuron into Organomineral Aggregates of Highly Weathered Tropical Soils.
abstract: We evaluated the effects of soil water content on the retention of diuron and its residual distribution into organomineral aggregates in four Brazilian oxisols. (14)C-Diuron was incubated for days at 25, 50, and 75% of maximum water-holding capacity for each soil. After 42 days, the physical fractionation method was used to obtain >150, 53-150, 20-53, 2-20, and <2 μm aggregate sizes. Diuron retention increased with increasing soil water content for all soils. At lower soil water content, diuron's retention was higher in the sandier soil. It was mostly retained in the fine (<20 μm) aggregates of sandier soil, and for clayed soils, retention was higher in the coarse aggregates (>53 μm). The sorption coefficients (Kd and Koc) generated by batch studies should be carefully used because they do not provide information about aggregation and diffusion effects on pesticides soil sorption.
authors.affiliation: Department of Soil Science, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo , Avenida Pádua Dias 11, C.P. 09, 13418-900 Piracicaba, São Paulo, Brazil.
authors.forename: Jussara B
authors.initials: JB
authors.lastname: Regitano
authors.affiliation: Embrapa Gado de Leite , Rua Eugênio do Nascimento 610, CEP 36038-330 Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Wadson S D
authors.initials: WS
authors.lastname: Rocha
authors.affiliation: Department of Soil and Agricultural Engineering, Federal University of Paraná , Rua dos Funcionários, 1540 Curitiba, Paraná, Brazil.
authors.forename: Eloana J
authors.initials: EJ
authors.lastname: Bonfleur
authors.affiliation: Embrapa Instrumentação Agropecuária , Rua XV de Novembro 1452, C.P 741, 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: Debora
authors.initials: D
authors.lastname: Milori
authors.affiliation: Department of Soil Science, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo , Avenida Pádua Dias 11, C.P. 09, 13418-900 Piracicaba, São Paulo, Brazil.
authors.forename: Luís R F
authors.initials: LR
authors.lastname: Alleoni
mesh_terms: D001938:Brazil; D004058:Diffusion; D004237:Diuron / Q000737:chemistry*; D007700:Kinetics; D010575:Pesticides / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D014867:Water; D004237:Diuron
keywords: oxisols; pesticide sorption; physical fractionation; soil organic matter; water diffusion