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On the natural fate of maleic hydrazide. Kinetic aspects of the photochemical and microbiological degradation of the herbicide

Paper ID Volume ID Publish Year Pages File Format Full-Text
30386 44475 2014 7 PDF Available
Title
On the natural fate of maleic hydrazide. Kinetic aspects of the photochemical and microbiological degradation of the herbicide
Abstract

•Maleic Hidrazide (MH) is degraded in the presence of riboflavin and visible light.•The photodegradative mechanism of MH is mediated by reactive oxygen species.•MH is biodegraded by the bacteria Pseudomonas aeruginosa.•The herbicide excerts a bacteriostatic effect on Bacillus subtilis.

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(1Δg)) are produced by electron- and energy-transfer processes, respectively, as demonstrated by auxiliary experiments employing selective auxiliary quenchers and the exclusive O2(1Δg) 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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Keywords
Biodegradation; Humic acid; Maleic hydrazide; Photodegradation; Riboflavin
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On the natural fate of maleic hydrazide. Kinetic aspects of the photochemical and microbiological degradation of the herbicide
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 135, 5 June 2014, Pages 48–54
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
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Price after discount Only $4.95
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