title: Siderophores in Cloud Waters and Potential Impact on Atmospheric Chemistry: Photoreactivity of Iron Complexes under Sun-Simulated Conditions.
abstract: In the present work, the photoreactivity of a mixture of iron(III)–pyoverdin (Fe(III)–Pyo) complexes was investigated under simulated cloud conditions. Pyoverdins are expected to complex ferric ions naturally present in cloudwater, thus modifying their availability and photoreactivity. The spectroscopic properties and photoreactivity of Fe(III)-Pyo were investigated, with particular attention to their fate under solar irradiation, also studied through simulations. The photolysis of the Fe(III)–Pyo complex leads to the generation of Fe(II), with rates of formation (RFe(II)f) of 6.98 and 3.96 × 10–9 M s–1 at pH 4.0 and 6.0, respectively. Interestingly, acetate formation was observed during the iron-complex photolysis, suggesting that fragmentation can occur after the ligand-to-metal charge transfer (LMCT) via a complex reaction mechanism. Moreover, photogenerated Fe(II) represent an important source of hydroxyl radical via the Fenton reaction in cloudwater. This reactivity might be relevant for the estimation of the rates of formation and steady-state concentrations of the hydroxyl radical by cloud chemistry models and for organic matter speciation in the cloud aqueous phase. In fact, the conventional models, which describe the iron photoreactivity in terms of iron–aqua and oxalate complexes, are not in accordance with our results.
authors.affiliation: Université Clermont Auvergne, Université Blaise Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.|CNRS, UMR 6296, ICCF, F-63171 Aubiere, France.
authors.forename: Monica
authors.initials: M
authors.lastname: Passananti
authors.affiliation: Université Clermont Auvergne, Université Blaise Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.|CNRS, UMR 6296, ICCF, F-63171 Aubiere, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Vinatier
authors.affiliation: Université Clermont Auvergne, Université Blaise Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.|CNRS, UMR 6296, ICCF, F-63171 Aubiere, France.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Delort
authors.affiliation: Université Clermont Auvergne, Université Blaise Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.|CNRS, UMR 6296, ICCF, F-63171 Aubiere, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Mailhot
authors.affiliation: Université Clermont Auvergne, Université Blaise Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.|CNRS, UMR 6296, ICCF, F-63171 Aubiere, France.
authors.forename: Marcello
authors.initials: M
authors.lastname: Brigante
mesh_terms: D005290:Ferric Compounds; D017665:Hydroxyl Radical; D007501:Iron; D010070:Oxalates; D010782:Photolysis; D017262:Siderophores
chemical_list: D005290:Ferric Compounds; D010070:Oxalates; D017262:Siderophores; D017665:Hydroxyl Radical; D007501:Iron