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dc.contributor.authorFitzsimmons, Jessica N.  Concept link
dc.contributor.authorBundy, Randelle M.  Concept link
dc.contributor.authorAl-Subiai, Sherain N.  Concept link
dc.contributor.authorBarbeau, Katherine A.  Concept link
dc.contributor.authorBoyle, Edward A.  Concept link
dc.date.accessioned2014-09-24T18:47:24Z
dc.date.available2014-09-24T18:47:24Z
dc.date.issued2014-09
dc.identifier.urihttps://hdl.handle.net/1912/6869
dc.descriptionAuthor Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Marine Chemistry 173 (2015): 125-135, doi:10.1016/j.marchem.2014.09.002.en_US
dc.description.abstractThe size partitioning of dissolved iron and organic iron-binding ligands into soluble and colloidal phases was investigated in the upper 150 m of two stations along the GA03 U.S. GEOTRACES North Atlantic transect. The size fractionation was completed using cross-flow filtration methods, followed by analysis by isotope dilution inductively-coupled plasma mass spectrometry (ID-ICP-MS) for iron and competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) for iron-binding ligands. On average, 80% of the 0.1-0.65 nM dissolved iron (<0.2 μm) was partitioned into the colloidal iron (cFe) size fraction (10 kDa < cFe < 0.2 μm), as expected for areas of the ocean underlying a dust plume. The 1.3-2.0 nM strong organic iron-binding ligands, however, overwhelmingly (75-77%) fell into the soluble size fraction (<10 kDa). As a result, modeling the dissolved iron size fractionation at equilibrium using the observed ligand partitioning did not accurately predict the iron partitioning into colloidal and soluble pools. This suggests that either a portion of colloidal ligands are missed by current electrochemical methods because they react with iron more slowly than the equilibration time of our CLE-ACSV method, or part of the observed colloidal iron is actually inorganic in composition and thus cannot be predicted by our model of unbound iron-binding ligands. This potentially contradicts the prevailing view that greater than 99% of dissolved iron in the ocean is organically complexed. Untangling the chemical form of iron in the upper ocean has important implications for surface ocean biogeochemistry and may affect iron uptake by phytoplankton.en_US
dc.description.sponsorshipJ.N. Fitzsimmons was funded by a National Science Foundation Graduate Research Fellowship (NSF Award #0645960). Research funding was provided by the National Science Foundation (OCE #0926204 and OCE #0926197) and the Center for Microbial Oceanography: Research and Education (NSF-OIA Award #EF-0424599) to E.A. Boyle. R.M. Bundy was partially funded by NSF OCE-0550302 and NSF OCE-1233733 to K.A. Barbeau and an NSF-GK12 graduate fellowship.en_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.relation.urihttps://doi.org/10.1016/j.marchem.2014.09.002
dc.subjectIronen_US
dc.subjectIron ligandsen_US
dc.subjectCLE-ACSVen_US
dc.subjectColloidsen_US
dc.subjectUltrafiltrationen_US
dc.subjectTrace metalsen_US
dc.subjectGEOTRACESen_US
dc.subjectNorth Atlantic Oceanen_US
dc.subjectChemical oceanographyen_US
dc.titleThe composition of dissolved iron in the dusty surface ocean : an exploration using size-fractionated iron-binding ligandsen_US
dc.typePreprinten_US


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