Gas-phase and particulate products from the atmospheric degradation of the organothiophosphorus insecticide chlorpyrifos-methyl. (November 2015)

• Record Type: Journal Article
• Authors: Borrás, Esther; Tortajada-Genaro, Luis Antonio; Ródenas, Milagros; Vera, Teresa; Coscollá, Clara; Yusá, Vicent; Muñoz, Amalia
• Is Part Of: Chemosphere. Volume 138(2015)
• Page Start: 888
• Page End: 894
• Publication Date: 2015-11
• Subjects: Chlorpyrifos-methyl -- Insecticide -- SOA -- Photo-oxidation -- Multi-oxygenated products -- Reaction mechanism; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2014.11.067
• Languages: English
• ISSNs: 0045-6535

Abstract

Graphical abstract: Highlights: Atmospheric OH-reaction of organothiophosphorus at a large outdoor simulation chamber. Reaction profiles and yields of chlorpyrifos-methyl products were determined. Phosphorothioate derivatives were the main degradation products observed. The degradation routes were formulate based on the structurally defined products. 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 NO x 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 PS 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.