Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications
The availability of iron has been thought to be a main limiting factor for the productivity of phytoplankton and related with the uptake of atmospheric CO_2 and algal blooms in fresh and sea waters. In this work, the formation of bioavailable iron (Fe(II)_(aq)) from the dissolution of iron oxide par...
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ftcaltechauth:oai:authors.library.caltech.edu:ngs5m-zme56 2024-10-13T14:11:02+00:00 Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications Kim, Kitae Choi, Wonyong Hoffmann, Michael R. Yoon, Ho-Il Park, Byong-Kwon 2010-06-01 https://doi.org/10.1021/es9037808 unknown American Chemical Society https://doi.org/10.1021/es9037808 eprintid:18715 info:eu-repo/semantics/openAccess Other Environmental Science and Technology, 44(11), 4142-4148, (2010-06-01) info:eu-repo/semantics/article 2010 ftcaltechauth https://doi.org/10.1021/es9037808 2024-09-25T18:46:46Z The availability of iron has been thought to be a main limiting factor for the productivity of phytoplankton and related with the uptake of atmospheric CO_2 and algal blooms in fresh and sea waters. In this work, the formation of bioavailable iron (Fe(II)_(aq)) from the dissolution of iron oxide particles was investigated in the ice phase under both UV and visible light irradiation. The photoreductive dissolution of iron oxides proceeded slowly in aqueous solution (pH 3.5) but was significantly accelerated in polycrystalline ice, subsequently releasing more bioavailable ferrous iron upon thawing. The enhanced photogeneration of Fe(II)_(aq) in ice was confirmed regardless of the type of iron oxides [hematite, maghemite (γ-Fe_2O_3), goethite (α-FeOOH)] and the kind of electron donors. The ice-enhanced dissolution of iron oxides was also observed under visible light irradiation, although the dissolution rate was much slower compared with the case of UV radiation. The iron oxide particles and organic electron donors (if any) in ice are concentrated and aggregated in the liquid-like grain boundary region (freeze concentration effect) where protons are also highly concentrated (lower pH). The enhanced photodissolution of iron oxides should occur in this confined boundary region. We hypothesized that electron hopping through the interconnected grain boundaries of iron oxide particles facilitates the separation of photoinduced charge pairs. The outdoor experiments carried out under ambient solar radiation of Ny-Ålesund (Svalbard, 78°55′N) also showed that the generation of dissolved Fe(II)_(aq) via photoreductive dissolution is enhanced when iron oxides are trapped in ice. Our results imply that the ice(snow)-covered surfaces and ice-cloud particles containing iron-rich mineral dusts in the polar and cold environments provide a source of bioavailable iron when they thaw. © 2010 American Chemical Society. Received December 14, 2009. Revised manuscript received April 15, 2010. Accepted April 20, 2010. Publication ... Article in Journal/Newspaper Svalbard Caltech Authors (California Institute of Technology) Svalbard Lesund ENVELOPE(8.470,8.470,63.331,63.331) Environmental Science & Technology 44 11 4142 4148 |
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Caltech Authors (California Institute of Technology) |
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ftcaltechauth |
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The availability of iron has been thought to be a main limiting factor for the productivity of phytoplankton and related with the uptake of atmospheric CO_2 and algal blooms in fresh and sea waters. In this work, the formation of bioavailable iron (Fe(II)_(aq)) from the dissolution of iron oxide particles was investigated in the ice phase under both UV and visible light irradiation. The photoreductive dissolution of iron oxides proceeded slowly in aqueous solution (pH 3.5) but was significantly accelerated in polycrystalline ice, subsequently releasing more bioavailable ferrous iron upon thawing. The enhanced photogeneration of Fe(II)_(aq) in ice was confirmed regardless of the type of iron oxides [hematite, maghemite (γ-Fe_2O_3), goethite (α-FeOOH)] and the kind of electron donors. The ice-enhanced dissolution of iron oxides was also observed under visible light irradiation, although the dissolution rate was much slower compared with the case of UV radiation. The iron oxide particles and organic electron donors (if any) in ice are concentrated and aggregated in the liquid-like grain boundary region (freeze concentration effect) where protons are also highly concentrated (lower pH). The enhanced photodissolution of iron oxides should occur in this confined boundary region. We hypothesized that electron hopping through the interconnected grain boundaries of iron oxide particles facilitates the separation of photoinduced charge pairs. The outdoor experiments carried out under ambient solar radiation of Ny-Ålesund (Svalbard, 78°55′N) also showed that the generation of dissolved Fe(II)_(aq) via photoreductive dissolution is enhanced when iron oxides are trapped in ice. Our results imply that the ice(snow)-covered surfaces and ice-cloud particles containing iron-rich mineral dusts in the polar and cold environments provide a source of bioavailable iron when they thaw. © 2010 American Chemical Society. Received December 14, 2009. Revised manuscript received April 15, 2010. Accepted April 20, 2010. Publication ... |
format |
Article in Journal/Newspaper |
author |
Kim, Kitae Choi, Wonyong Hoffmann, Michael R. Yoon, Ho-Il Park, Byong-Kwon |
spellingShingle |
Kim, Kitae Choi, Wonyong Hoffmann, Michael R. Yoon, Ho-Il Park, Byong-Kwon Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications |
author_facet |
Kim, Kitae Choi, Wonyong Hoffmann, Michael R. Yoon, Ho-Il Park, Byong-Kwon |
author_sort |
Kim, Kitae |
title |
Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications |
title_short |
Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications |
title_full |
Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications |
title_fullStr |
Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications |
title_full_unstemmed |
Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications |
title_sort |
photoreductive dissolution of iron oxides trapped in ice and its environmental implications |
publisher |
American Chemical Society |
publishDate |
2010 |
url |
https://doi.org/10.1021/es9037808 |
long_lat |
ENVELOPE(8.470,8.470,63.331,63.331) |
geographic |
Svalbard Lesund |
geographic_facet |
Svalbard Lesund |
genre |
Svalbard |
genre_facet |
Svalbard |
op_source |
Environmental Science and Technology, 44(11), 4142-4148, (2010-06-01) |
op_relation |
https://doi.org/10.1021/es9037808 eprintid:18715 |
op_rights |
info:eu-repo/semantics/openAccess Other |
op_doi |
https://doi.org/10.1021/es9037808 |
container_title |
Environmental Science & Technology |
container_volume |
44 |
container_issue |
11 |
container_start_page |
4142 |
op_container_end_page |
4148 |
_version_ |
1812818650813431808 |