Adsorption of glyphosate on Brazilian subtropical soils rich in iron and aluminum oxides

Autor(es)

Oliveira Pereira, Erico A. ^[1] ; Melo, Vander Freitas ^[2] ; Abate, Gilberto ^[3] ; Masini, Jorge C. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Sao Paulo - Brazil

^[2] Univ Fed Parana, Dept Solos & Engn Agr, Setor Ciencias Agr, Curitiba, Parana - Brazil

^[3] Univ Fed Parana, Dept Quim, Curitiba, Parana - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART B-PESTICIDES FOOD CONTAMIN; v. 54, n. 11 JULY 2019.
• Citações Web of Science: 1

Resumo

We investigated the adsorption of glyphosate onto five subtropical soils of Parana and Sao Paulo states, Brazil, a region of intense agricultural activities, aiming at the determination of kinetic and isotherm adsorption parameters which enable the evaluation of the potential leaching of the herbicide. The adsorption was fast, being described by the pseudo-second order and intraparticle diffusion models, thus suggesting that mixed mechanisms are involved. The Oxisol containing the highest concentrations of metal oxides (209.5 g kg(-1) Fe2O3 and 160.2 g kg(-1) Al2O3) was the sample with the highest rate constant, indicating the adsorption sites are readily available. All the soils are rich in aluminum and iron oxides, explaining the Freundlich coefficients (K-F) between 642 and 1360 mg(1-1/n) kg(-1) L-1/n, which are higher than most of the coefficients described for other soils around the world. The maximum desorption (15% of the adsorbed amount) was observed for the Oxisol. For the other soils, desorption ranged from 2 to 7%. These results suggest that the leaching of free glyphosate to nearby surface and groundwaters is unlikely unless excessive doses are used. The adsorption parameters are useful for managing the right doses applied to the crops, thus avoiding contamination of adjacent areas. (AU)

• Processo FAPESP: 13/18507-4 - Materiais monolíticos porosos para separações cromatográficas e preparo de amostras
• Beneficiário: Jorge Cesar Masini
• Modalidade de apoio: Auxílio à Pesquisa - Regular