title: The gas-phase degradation of chlorpyrifos and chlorpyrifos-oxon towards OH radical under atmospheric conditions.
abstract: The OH initiated oxidation of chlorpyrifos (a widely used insecticide) and its photooxidation product chlorpyrifos-oxon were investigated at the large outdoor European Photoreactor (EUPHORE). The rate constants for reaction of chlorpyrifos and chlorpyrifos oxon with OH radicals were measured using a conventional relative rate method. The value of the OH reaction rate constants with chlorpyrifos and chlorpyrifos-oxon were determined to be k=(9.1±2.1)×10(-11)cm(3)molecule(-1)s(-1) and (1.7±0.9)×10(-11)cm(3)molecule(-1)s(-1) at 303±5K and atmospheric pressure. They gave an atmospheric lifetime in relation to the reaction with OH of approximately 2h and 11h for chlorpyrifos and chlorpyrifos-oxon, respectively. Photolysis was found to be unimportant relative to reaction with OH. The main products detected in the gas phase from the reaction of OH with chlorpyrifos were SO2, chlorpyrifos-oxon, 3,5,6-trichloro-2-pyridinol and diethylphosphate with molar yields of 17±5%, ∼10%, 8±4% and 30±9%, respectively.
authors.affiliation: EUPHORE, Instituto Universitario UMH-CEAM, C/Charles R. Darwin, 14, Parque Tecnológico, 46980 Paterna, Valencia, Spain. Electronic address: amalia@ceam.es.
authors.forename: Amalia
authors.initials: A
authors.lastname: Muñoz
authors.affiliation: EUPHORE, Instituto Universitario UMH-CEAM, C/Charles R. Darwin, 14, Parque Tecnológico, 46980 Paterna, Valencia, Spain.
authors.forename: Milagros
authors.initials: M
authors.lastname: Ródenas
authors.affiliation: EUPHORE, Instituto Universitario UMH-CEAM, C/Charles R. Darwin, 14, Parque Tecnológico, 46980 Paterna, Valencia, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Borrás
authors.affiliation: EUPHORE, Instituto Universitario UMH-CEAM, C/Charles R. Darwin, 14, Parque Tecnológico, 46980 Paterna, Valencia, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Vázquez
authors.affiliation: EUPHORE, Instituto Universitario UMH-CEAM, C/Charles R. Darwin, 14, Parque Tecnológico, 46980 Paterna, Valencia, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Vera
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry*; D001272:Atmosphere / Q000032:analysis; D004390:Chlorpyrifos / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D005740:Gases / Q000032:analysis / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D007306:Insecticides / Q000032:analysis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010782:Photolysis; D011728:Pyridones / Q000032:analysis
chemical_list: D000393:Air Pollutants; D005740:Gases; D007306:Insecticides; D011728:Pyridones; D017665:Hydroxyl Radical; C009618:O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphate; C012587:3,5,6-trichloro-2-pyridinol; D004390:Chlorpyrifos
keywords: Atmospheric degradation; Chlorpyrifos; Chlorpyrifos-oxon; Photooxidation