title: Gas-phase and particulate products from the atmospheric degradation of the organothiophosphorus insecticide chlorpyrifos-methyl.
abstract: The phosphorothioate structure is highly present in several organophosphorus pesticides. However, there is insufficient information about its degradation process after the release to the atmosphere and the secondary pollutants formed. Herein, the atmospheric reaction of chlorpyrifos-methyl (o,o-dimethyl o-(3,5,6-trichloropyridin-2-yl) phosphorothioate), is described for semi-urban or rural locations. The photo-oxidation under low NOx conditions (5-55 ppbV) was reproduced in a large outdoor simulation chamber, observing a rapid degradation (lifetime<3.5 h). The formation of gaseous products and particulate matter (aerosol yield 2-8%) was monitored. The chemical composition of minor products (gaseous and particulate) was studied, identifying 15 multi-oxygenated derivatives. The most abundant products were ring-retaining molecules such as o,o-dimethyl o-(3,5,6-trichloropyridin-2-yl) phosphorothioate, dimethyl 3,5,6-trichloropyridin-2-yl phosphate, o-methyl o-(3,5,6-trichloropyridin-2-yl) hydrogen phosphorothioate, 3,5,6-trichloropyridin-2-yl dihydrogen phosphate, 3,5,6-trichloropyridin-2-ol, and 3,5,6-trichloropyridine-2,4-diol. An atmospheric degradation mechanism has been proposed based on an oxidation started with OH-nucleophilic attack to P=S bond. The results have been extrapolated to other organothiophosphorus molecules, such as malathion, parathion, diazinon and methidathion, among many others, to estimate their photo-oxidative degradation and the expected products.
authors.affiliation: Centro de Estudios Ambientales del Mediterráneo (Fundación CEAM), Spain; Atmospheric Pesticide Research Group of Valencia, Valencia, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Borrás
authors.affiliation: Instituto de Reconocimiento Molecular y Desarrollo Tecnológico-Departamento Química, Universitat Politècnica de València, Spain.
authors.forename: Luis Antonio
authors.initials: LA
authors.lastname: Tortajada-Genaro
authors.affiliation: Centro de Estudios Ambientales del Mediterráneo (Fundación CEAM), Spain; Atmospheric Pesticide Research Group of Valencia, Valencia, Spain.
authors.forename: Milagros
authors.initials: M
authors.lastname: Ródenas
authors.affiliation: Centro de Estudios Ambientales del Mediterráneo (Fundación CEAM), Spain; Atmospheric Pesticide Research Group of Valencia, Valencia, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Vera
authors.affiliation: Public Health Laboratory of Valencia-FISABIO, 21, Avenida Catalunya, 46020 Valencia, Spain; Atmospheric Pesticide Research Group of Valencia, Valencia, Spain.
authors.forename: Clara
authors.initials: C
authors.lastname: Coscollá
authors.affiliation: Public Health Laboratory of Valencia-FISABIO, 21, Avenida Catalunya, 46020 Valencia, Spain; Atmospheric Pesticide Research Group of Valencia, Valencia, Spain.
authors.forename: Vicent
authors.initials: V
authors.lastname: Yusá
authors.affiliation: Centro de Estudios Ambientales del Mediterráneo (Fundación CEAM), Spain; Atmospheric Pesticide Research Group of Valencia, Valencia, Spain. Electronic address: amalia@ceam.es.
authors.forename: Amalia
authors.initials: A
authors.lastname: Muñoz
mesh_terms: D001272:Atmosphere / Q000737:chemistry*; D004390:Chlorpyrifos / Q000031:analogs & derivatives* / Q000737:chemistry; D004785:Environmental Pollutants / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D006801:Humans; D052638:Particulate Matter / Q000737:chemistry; D010575:Pesticides / Q000737:chemistry*; D010782:Photolysis
chemical_list: D004785:Environmental Pollutants; D005740:Gases; D052638:Particulate Matter; D010575:Pesticides; D004390:Chlorpyrifos; C007031:chlorpyrifos-methyl
keywords: Chlorpyrifos-methyl; Insecticide; Multi-oxygenated products; Photo-oxidation; Reaction mechanism; SOA