title: Heterogeneous reaction of suspended phosmet particles with NO3 radicals.
abstract: As an organophosphorous insecticide, phosmet is widely used for plant protection as well as against the ectoparasites on productive livestock. It emits into the atmosphere in both gas and particulate phases via spray drift from treatments and postapplication emissions, but its degradation in the atmosphere is not well-known up to now. In this study, the heterogeneous reaction of phosmet absorbed on the azelaic acid particles with NO(3) radicals is investigated in real-time using a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). Two primary products and their nitro-substituted derivates are observed. The apparent reaction rate of phosmet particles with NO(3) radicals is also obtained by a relative rate method with isoprene and 1,4-cyclohexadiene as the reference compounds. The concentrations of the reference substance and phosmet particles are synchronously detected with an atmospheric gas analysis mass spectrometer and the VUV-ATOFMS. Under the experimental conditions, the average apparent reaction rate obtained is (1.92 ± 0.09) × 10(-12) cm(3) molecule(-1) s(-1), and the corresponding atmospheric lifetime toward NO(3) radicals is roughly estimated to be ~0.3 h.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Changgeng
authors.initials: C
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Gan
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Miao
authors.initials: M
authors.lastname: Liang
authors.forename: Xi
authors.initials: X
authors.lastname: Shu
authors.forename: Jinian
authors.initials: J
authors.lastname: Shu
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
mesh_terms: D003998:Dicarboxylic Acids / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D015394:Molecular Structure; D009566:Nitrates / Q000737:chemistry*; D010706:Phosmet / Q000737:chemistry*
chemical_list: D003998:Dicarboxylic Acids; D005609:Free Radicals; D009566:Nitrates; C010038:azelaic acid; D010706:Phosmet