title: Oxygen isotope signature of UV degradation of glyphosate and phosphonoacetate: tracing sources and cycling of phosphonates.
abstract: The degradation of phosphonates in the natural environment constitutes a major route by which orthophosphate (Pi) is regenerated from organic phosphorus and recently implicated in marine methane production, with ramifications to environmental pollution issues and global climate change concerns. This work explores the application of stable oxygen isotope analysis in elucidating the CP bond cleavage mechanism(s) of phosphonates by UV photo-oxidation and for tracing their sources in the environment. The two model phosphonates used, glyphosate and phosphonoacetic acid were effectively degraded after exposure to UV irradiation. The isotope results indicate the involvement of both ambient water and atmospheric oxygen in the CP bond cleavage and generally consistent with previously posited mechanisms of UV-photon excitation reactions. A model developed to calculate the oxygen isotopic composition of the original phosphonate P-moiety, shows both synthetic phosphonates having distinctly lower values compared to naturally derived organophosphorus compounds. Such mechanistic models, based on O-isotope probing, are useful for tracing the sources and reactions of phosphonates in the environment.
authors.affiliation: State Key Laboratory of Biogeology & Environmental Geology, China University of Geosciences, Wuhan 430074, PR China.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sandy
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Blake
authors.forename: Sae Jung
authors.initials: SJ
authors.lastname: Chang
authors.forename: Yao
authors.initials: Y
authors.lastname: Jun
authors.forename: Chan
authors.initials: C
authors.lastname: Yu
mesh_terms: D001673:Biodegradation, Environmental; D004785:Environmental Pollutants / Q000737:chemistry; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D006868:Hydrolysis; D008697:Methane / Q000737:chemistry; D008956:Models, Chemical; D063065:Organophosphonates / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010103:Oxygen Isotopes / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D010746:Phosphonoacetic Acid / Q000737:chemistry*; D010782:Photolysis; D013997:Time Factors; D014466:Ultraviolet Rays; D000097797:Glyphosate
chemical_list: D004785:Environmental Pollutants; D005998:Glycine; D008697:Methane; D063065:Organophosphonates; D016877:Oxidants; D010103:Oxygen Isotopes; D010710:Phosphates; D010746:Phosphonoacetic Acid; D000097797:Glyphosate
keywords: Phosphate; Phosphonates; Photo-oxidation; Stable isotope analysis