| Autor: |
Abou-Ghanem M; Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada., Oliynyk AO; Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.; Now at Chemistry and Biochemistry Department, Manhattan College, Riverdale, New York, New York 10471, United States., Chen Z; Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada., Matchett LC; Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.; Now at Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4L8, Canada., McGrath DT; Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3X7, Canada., Katz MJ; Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3X7, Canada., Locock AJ; Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2G2, Canada., Styler SA; Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.; Now at Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada. |
| Abstrakt: |
The billions of tons of mineral dust released into the atmosphere each year provide an important surface for reaction with gas-phase pollutants. These reactions, which are often enhanced in the presence of light, can change both the gas-phase composition of the atmosphere and the composition and properties of the dust itself. Because dust contains titanium-rich grains, studies of dust photochemistry have largely employed commercial titanium dioxide as a proxy for its photochemically active fraction; to date, however, the validity of this model system has not been empirically determined. Here, for the first time, we directly investigate the photochemistry of the complement of natural titanium-containing minerals most relevant to mineral dust, including anatase, rutile, ilmenite, titanite, and several titanium-bearing species. Using ozone as a model gas-phase pollutant, we show that titanium-containing minerals other than titanium dioxide can also photocatalyze trace gas uptake, that samples of the same mineral phase can display very different reactivity, and that prediction of dust photoreactivity based on elemental/mineralogical analysis and/or light-absorbing properties is challenging. Together, these results show that the photochemistry of atmospheric dust is both richer and more complex than previously considered, and imply that a full understanding of the scope and impact of dust-mediated processes will require the community to engage with this complexity via the study of ambient mineral dust samples from diverse source regions. |
