On the natural fate of maleic hydrazide. Kinetic aspects of the photochemical and microbiological degradation of the herbicide.
J Photochem Photobiol B
; 135: 48-54, 2014 Jun 05.
Article
em En
| MEDLINE
| ID: mdl-24796645
Kinetic and mechanistic aspects of the photochemical and microbiological degradation of the herbicide Maleic Hydrazide (MH) have been studied. Riboflavin (Rf, vitamin B2) was employed as a main photosensitizer whereas Humic Acid (HA) was included as a second sensitizer in order to more closely simulate natural environmental conditions. MH quenches excited singlet and triplet states of Rf, with rate constants close to the diffusion limit. The herbicide and dissolved molecular oxygen competitively quench triplet excited Rf. As a consequence the reactive oxygen species (ROS), superoxide radical anion (O2(-·)), hydrogen peroxide (H2O2) and singlet molecular oxygen (O2((1)Δg)) are produced by electron- and energy-transfer processes, respectively, as demonstrated by auxiliary experiments employing selective auxiliary quenchers and the exclusive O2((1)Δg) generator Rose Bengal (RB). As a global result, the photodegradation of Rf is retarded, whereas MH is degraded by the generated ROS. The bacteria Pseudomonas aeruginosa (Ps) and Bacillus subtilis (Bs), recognized as contaminants surface-water and soil and microbial antagonists of phytopathogenic, were used in the microbiological experiments. Results of the individual incubation of both bacteria in in the presence of MH indicate a stimulation on the Ps growth, implying the biodegradation of the herbicide, whereas MH only exerted a bacteriostatic effect on Bs.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fotólise
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Pseudomonas aeruginosa
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Bacillus subtilis
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Herbicidas
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Hidrazida Maleica
Idioma:
En
Revista:
J Photochem Photobiol B
Assunto da revista:
BIOLOGIA
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Suíça