title: Studies on the atmospheric degradation of chlorpyrifos-methyl.
abstract: The gas-phase atmospheric degradation of chlorpyrifos-methyl (a widely used organophosphate insecticide in Southern European regions) has been investigated at the large outdoor European Photoreactor (EUPHORE) in Valencia, Spain. Photolysis under sunlight conditions and reaction with ozone were shown to be unimportant. The rate constant for reaction of chlorpyrifos-methyl with OH radicals was measured using a conventional relative rate method with cyclohexane and n-octane employed as reference compounds with k = (4.1 ± 0.4) × 10(-11) cm(3) molecule(-1) s(-1) at 300 ± 5 K and atmospheric pressure. The available evidence indicates that tropospheric degradation of chlorpyrifos-methyl is mainly controlled by reaction with OH radicals and that the tropospheric lifetime is estimated to be around 3.5 h. Significant aerosol formation was observed following the reaction of chlorpyrifos-methyl with OH radicals, and the main carbon-containing products detected in the gas phase were chlorpyrifos-methyl oxone and 3,5,6-trichloro-2-pyridinol.
authors.affiliation: Instituto Universitario CEAM-UMH, 14 Parque Tecnológico, 46980 Paterna, Valencia, Spain. amalia@ceam.es
authors.forename: Amalia
authors.initials: A
authors.lastname: Muñoz
authors.forename: Teresa
authors.initials: T
authors.lastname: Vera
authors.forename: Howard
authors.initials: H
authors.lastname: Sidebottom
authors.forename: Abdelwahid
authors.initials: A
authors.lastname: Mellouki
authors.forename: Esther
authors.initials: E
authors.lastname: Borrás
authors.forename: Milagros
authors.initials: M
authors.lastname: Ródenas
authors.forename: Eva
authors.initials: E
authors.lastname: Clemente
authors.forename: Mónica
authors.initials: M
authors.lastname: Vázquez
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D001272:Atmosphere / Q000737:chemistry*; D004390:Chlorpyrifos / Q000031:analogs & derivatives* / Q000737:chemistry; D004784:Environmental Monitoring; D017665:Hydroxyl Radical / Q000737:chemistry; D007306:Insecticides / Q000737:chemistry*; D007700:Kinetics; D008970:Molecular Weight; D010782:Photolysis; D013472:Sunlight; D013696:Temperature
chemical_list: D000393:Air Pollutants; D007306:Insecticides; D017665:Hydroxyl Radical; D004390:Chlorpyrifos; C007031:chlorpyrifos-methyl