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Fan S, Gao Y, Lai B, Elzinga EJ, Yu S. Aerosol iron speciation and seasonal variation of iron oxidation state over the western Antarctic Peninsula. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 824:153890. [PMID: 35182624 DOI: 10.1016/j.scitotenv.2022.153890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/07/2022] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
The iron (Fe) speciation and oxidation state have been considered critical factors affecting Fe solubility in the atmosphere and bioavailability in the surface ocean. In this study, elemental composition and Fe speciation in aerosol samples collected at the Palmer Station in the West Antarctic Peninsula were determined using synchrotron-based X-ray fluorescence (XRF) and X-ray Absorption Near-Edge Structure (XANES) spectroscopy. The elemental composition of coarse-mode (>1 μm) Fe-containing particles suggests that the region's crustal emission is the primary source of aerosol Fe. The Fe minerals in these aerosol particles were predominantly hematite and biotite, but minor fractions of pyrite and ilmenite were observed as well. The Fe oxidation state showed an evident seasonal variation. The Fe(II) content accounted for 71% of the total Fe in the austral summer, while this fraction dropped to 60% in the austral winter. Multivariate linear models involving meteorological parameters suggested that the wind speed, relative humidity, and solar irradiance were the factors that significantly controlled the percentage of Fe(II) in the austral summer. On the contrary, no relationship was found between these factors and the Fe(II) percentage in the austral winter, suggesting that atmospheric photoreduction and regional dust emission were limited. Moreover, the snow depth was significantly (p < 0.05) correlated with the aerosol Fe concentration, confirming the limiting effect of snow/ice cover on the regional dust emission. Given that the Antarctic Peninsula has experienced rapid warming during recent decades, the ice-free areas in the Antarctic Peninsula may act as potential dust sources.
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Affiliation(s)
- Songyun Fan
- Department of Earth and Environmental Sciences, Rutgers University, Newark, NJ 07102, USA
| | - Yuan Gao
- Department of Earth and Environmental Sciences, Rutgers University, Newark, NJ 07102, USA.
| | - Barry Lai
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Evert J Elzinga
- Department of Earth and Environmental Sciences, Rutgers University, Newark, NJ 07102, USA
| | - Shun Yu
- Department of Earth and Environmental Sciences, Rutgers University, Newark, NJ 07102, USA
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Wang Y, Brigante M, Mailhot G, Talaga D, Wu Y, Dong W, Sobanska S. Toward a better understanding of ferric-oxalate complex photolysis: The role of the aqueous/air interface of droplet. CHEMOSPHERE 2022; 289:133127. [PMID: 34864008 DOI: 10.1016/j.chemosphere.2021.133127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/02/2021] [Accepted: 11/28/2021] [Indexed: 06/13/2023]
Abstract
In this work, the photo reactivity of ferric oxalate (Fe(III)-Ox) complex in atmospheric particles was investigated. Raman spectroscopy was used to explore the mechanism and kinetics of Fe(III)-Ox photolysis occurring at the aqueous/gas interface, inside the droplet and in bulk solution. Ferrous carbonate (FeCO3) was detected indicating that carbonate ion (CO32-) formed inside the droplets would compete with oxalate ligands for iron complexation. A higher concentration of photoproduct Fe(II)-Ox was observed at the surface and inside of the droplets than in bulk solution. In particular, Fe(III)-Ox on the droplet surface was quickly reduced with light and Fe(II)-Ox concentration gradually decreased with irradiation time. The evolution of Fe(II)-Ox concentration was similar inside the droplet and in bulk solution with a trend of first increasing and then gradually decreasing during irradiation time. Although FeCO3 would hinder Fenton intermediate reaction, the photolysis rate of Fe(III)-Ox in droplets was almost two orders of magnitude times faster than that observed during bulk experiment. In general, the photolysis mechanism and kinetics of Fe(III)-Ox in aqueous/air interface, inside of droplet and bulk solution were distinct, and the production of oxide species from the atmospheric Fe(III)-Ox droplets was underestimated.
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Affiliation(s)
- Yu Wang
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200438, China; Institut des Sciences Moléculaires, UMR CNRS 5255, Univ. Bordeaux, Talence, F-33405, France
| | - Marcello Brigante
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut de Chimie de Clermont-Ferrand, F-63000, Clermont-Ferrand, France
| | - Gilles Mailhot
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut de Chimie de Clermont-Ferrand, F-63000, Clermont-Ferrand, France
| | - David Talaga
- Institut des Sciences Moléculaires, UMR CNRS 5255, Univ. Bordeaux, Talence, F-33405, France
| | - Yanlin Wu
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200438, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Wenbo Dong
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200438, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
| | - Sophie Sobanska
- Institut des Sciences Moléculaires, UMR CNRS 5255, Univ. Bordeaux, Talence, F-33405, France.
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Liu Q, Liggio J, Li K, Lee P, Li SM. Understanding the Impact of Relative Humidity and Coexisting Soluble Iron on the OH-Initiated Heterogeneous Oxidation of Organophosphate Flame Retardants. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6794-6803. [PMID: 31117542 DOI: 10.1021/acs.est.9b01758] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The current uncertainties in the reactivity and atmospheric persistence of particle-associated chemicals present a challenge for the prediction of long-range transport and deposition of emerging chemicals such as organophosphate flame retardants, which are ubiquitous in the global environment. Here, the OH-initiated heterogeneous oxidation kinetics of organophosphate flame retardants (OPFRs) coated on inert (NH4)2SO4 and redox-active FeSO4 particles were systematically determined as a function of relative humidity (RH). The derived reaction rate constants for the heterogeneous loss of tricresyl phosphate (TCP; kTCP) and tris(2-butoxyethyl) phosphate (TBEP; kTBEP) were in the range of (2.69-3.57) × 10-12 and (3.06-5.55) × 10-12 cm3 molecules-1 s-1, respectively, depending on the RH and coexisting Fe(II) content. The kTCP (coated on (NH4)2SO4) was relatively constant over the investigated RH range while kTBEP was enhanced by up to 19% with increasing RH. For both OPFRs, the presence of Fe(II) enhanced their k by up to 53% over inert (NH4)2SO4. These enhancement effects (RH and Fe(II)) were attributed to fundamental changes in the organic phase state (higher RH lowered particle viscosity) and Fenton-type chemistry which resulted in the formation of reactive oxygen species, respectively. Such findings serve to emphasize the importance of ambient RH, the phase state of particle-bound organics in general, and the presence of coexisting metallic species for an accurate description of the degradation kinetics and aging of particulate OPFRs in models used to evaluate their atmospheric persistence.
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Affiliation(s)
- Qifan Liu
- Atmospheric Science and Technology Directorate, Science and Technology Branch , Environment Canada , 4905 Dufferin Street , Toronto , Ontario M3H 5T4 , Canada
| | - John Liggio
- Atmospheric Science and Technology Directorate, Science and Technology Branch , Environment Canada , 4905 Dufferin Street , Toronto , Ontario M3H 5T4 , Canada
| | - Kun Li
- Atmospheric Science and Technology Directorate, Science and Technology Branch , Environment Canada , 4905 Dufferin Street , Toronto , Ontario M3H 5T4 , Canada
| | - Patrick Lee
- Atmospheric Science and Technology Directorate, Science and Technology Branch , Environment Canada , 4905 Dufferin Street , Toronto , Ontario M3H 5T4 , Canada
| | - Shao-Meng Li
- Atmospheric Science and Technology Directorate, Science and Technology Branch , Environment Canada , 4905 Dufferin Street , Toronto , Ontario M3H 5T4 , Canada
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