Please use this identifier to cite or link to this item:
Title: Sunlight and UVC-254 irradiation induced photodegradation of organophosphorus pesticide dichlorvos in aqueous matrices
Author: Bustos, Nahuel
Cruz Alcalde, Alberto
Iriel, Analía
Fernández Cirelli, Alicia
Sans Mazón, Carme
Keywords: Àcid húmic
Humic acid
Issue Date: 1-Feb-2019
Publisher: Elsevier B.V.
Abstract: Dichlorvos (DDVP) is an organophosphorus pesticide that has been classified as highly hazardous chemical by the World Health organization. In this study, the fate of the pesticide DDVP in natural water compartments was examined under simulated sunlight. Moreover, the effect of UV-254 irradiation on DDVP depletion was also studied. In deionized water, DDVP was photodegraded only in the presence of dissolved molecular oxygen. The photodegradation during the first 6 h of sunlight irradiation occurred with pseudo first-order kinetics, and the rate constants were 0.040 h−1 at pH 7 and 0.064 h−1 at pH 3. A reactionmechanismfor the generation of reactive oxygen species (ROS) via DDVP photoabsorption was proposed. Humic acids (HA) played a double role as photosensitizer and inhibitor, observing an enhancement on DDVP photodegradation at low HA concentration (TOC=2 mg L−1). The depletion of DDVP under 254 nmUV irradiationwas ascribed to direct photodegradation and oxygenmediated photoinduced reactions. Direct photodegradation of DDVP decreased with 254 nm irradiation reduction, highlighting the importance of radicalmediatedmechanisms at low irradiation doses. Based on LC/MS data, themain photoproducts under simulated solar light and UV-C irradiation were identified and potential reaction pathways were postulated. The three main identified products were o-methyl 2,2-dichlorovinyl phosphate, dichloroacetaldehyde and dimethylphosphate. Moreover, the toxicity of samples was evaluated along the irradiation exposure time using Microtox® assays. This study brings new insights into the role of oxygen in the photodegradation of DDVP and the induced and inhibitionmechanisms involved in the presence of the humic acids in natural waters.
Note: Versió postprint del document publicat a:
It is part of: Science of the Total Environment, 2019, vol. 649, p. 592-600
Related resource:
ISSN: 0048-9697
Appears in Collections:Articles publicats en revistes (Enginyeria Química i Química Analítica)

Files in This Item:
File Description SizeFormat 
681865.pdf1.15 MBAdobe PDFView/Open

This item is licensed under a Creative Commons License Creative Commons