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Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications SCIE SCOPUS

Title
Photoreductive Dissolution of Iron Oxides Trapped in Ice and Its Environmental Implications
Authors
Kim, KChoi, WHoffmann, MRYoon, HIPark, BK
Date Issued
2010-06-01
Publisher
AMER CHEMICAL SOC
Abstract
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 CO2 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 (gamma-Fe2O3), goethite (alpha-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-Alesund (Svalbard, 78 degrees 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.
Keywords
LIGHT-INDUCED DISSOLUTION; SOUTHERN-OCEAN; PHOTOCHEMISTRY; PHYTOPLANKTON; MONOCHLOROPHENOLS; FERTILIZATION; ACCELERATION; CONSEQUENCES; ALPHA-FE2O3; OXIDATION
URI
https://oasis.postech.ac.kr/handle/2014.oak/25848
DOI
10.1021/ES9037808
ISSN
0013-936X
Article Type
Article
Citation
ENVIRONMENTAL SCIENCE & TECHNOLOGY, vol. 44, no. 11, page. 4142 - 4148, 2010-06-01
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최원용CHOI, WONYONG
Div of Environmental Science & Enginrg
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