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Title: Characterization of iron oxide nanoparticle films at the air–water interface in Arctic tundra waters

Here, massive amounts of organic carbon have accumulated in Arctic permafrost and soils due to anoxic and low temperature conditions that limit aerobic microbial respiration. Alternative electron acceptors are thus required for microbes to degrade organic carbon in these soils. Iron or iron oxides have been recognized to play an important role in carbon cycle processes in Arctic soils, although the exact form and role as an electron acceptor or donor remain poorly understood. Here, Arctic biofilms collected during the summers of 2016 and 2017 from tundra surface waters on the Seward Peninsula of western Alaska were characterized with a suite of microscopic and spectroscopic methods. We hypothesized that these films contain redox-active minerals bound to biological polymers. The major components of the films were found to be iron oxide nanoparticle aggregates associated with extracellular polymeric substances. The observed mineral phases varied between films collected in different years with magnetite (Fe 2+Fe 2 3+O 4) nanoparticles (<5 nm) predominantly identified in the 2016 films, while for films collected in 2017 ferrihydrite-like amorphous iron oxyhydroxides were found. While the exact formation mechanism of these Artic iron oxide films remains to be explored, the presence of magnetite and other iron oxide/oxyhydroxide nanoparticlesmore » at the air–water interface may represent a previously unknown source of electron acceptors for continual anaerobic microbial respiration of organic carbon within poorly drained Arctic tundra.« less
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [2] ; ORCiD logo [2] ; ORCiD logo [2] ; ORCiD logo [2] ; ORCiD logo [2] ;  [2] ; ORCiD logo [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eastern Energy Resources Science Center, Reston, VA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Science of the Total Environment
Additional Journal Information:
Journal Volume: 633; Journal Issue: C; Journal ID: ISSN 0048-9697
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; Magnetite; Ferrihydrite; Extracellular polymeric substance; Transmission electron microscopy; Surface enhanced Raman scattering; Coupled iron and carbon cycle
OSTI Identifier: