Data/hora: 05/06/2024 13:22:06

Biblioteca(s): | Embrapa Instrumentação.
Data corrente: | 22/12/1999
Data da última atualização: | 22/12/1999
Autoria: | SPOSITO, G.; MARTIN-NETO, L.; YANG, A.
Afiliação: | University of California-Ecosystem Sciences Division; EMBRAPA-CNPDIA.
Título: | Atrazine complexation by soil humic acids.
Ano de publicação: | 1996
Fonte/Imprenta: | Journal of Environmental Quality, Madison, v.25, n.6, p.1203-1209, Nov./Dec. 1996.
Idioma: | Inglês
Conteúdo: | Atrazine complexation pathways with soil humic acid remain a controversial issue, in part because of the absence of direct spectroscopic information. Recent optical and magnetic resonance spectral data indicate that proton-transfer and, to a lesser extent, hydrogen bonding are as important as electron-transfer in the mechanisms of reaction between atrazine and humic acid, whereas other s-triazines appear to react more strongly by electron transfer mechanisms. Two representative temperate-zone humic acids were selected to probe the issue of complexation mechanisms more decisively. They were reacted at pH < 7 with 140mmol mE-3 atrazine solution under exclusion of light. Infrared and electron spin resonance spectra of the resulting products gave evidence for proton-transfer and, under certain conditions, electron-transfer reactions. The spectroscopic data were analyzed in terms of the molecular properties of humic acids and s-triazines. The analysis suggested a general guiding principle to characterize the complexation mechanisms of s-triazines with soil humic acids. Proton-transfer is favored (and electron-transfer is disfavored) for humic acids of high acidic functional group content and for s-triazines of low basicity. Electron-transfer mechanisms are favored for humic acids of low acidic functional group content and for s-triazines of high basicity. This principle illustrates the importance of specific molecular structure to understanding reactivity between the s-triazines and humic acids.
Categoria do assunto: | --
Registro original: | Embrapa Instrumentação (CNPDIA)
Exemplares: | CNPDIA - (5040-1) - UPC - SP - -- - PROCI-96.00180 -  - 1996.00180 - DIS