Basin scale survey of marine humic fluorescence in the Atlantic: relationship to iron solubility and H2O2.

Heller, Maija, Gaiero, Diego and Croot, Peter (2013) Basin scale survey of marine humic fluorescence in the Atlantic: relationship to iron solubility and H2O2. Open Access Global Biogeochemical Cycles, 27 . pp. 1-14. DOI 10.1029/2012GB004427.

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Abstract

Iron (Fe) is a limiting nutrient for phytoplankton productivity in many different oceanic regions. A critical aspect underlying iron limitation is its low solubility in seawater as this controls the distribution and transport of iron through the ocean. Processes which enhance the solubility of iron in seawater, either through redox reactions or organic complexation, are central to understanding the biogeochemical cycling of iron. In this work we combined iron solubility measurements with parallel factor (PARAFAC) data analysis of CDOM fluorescence along a meridional transect through the Atlantic (PS ANT XXVI-4) to examine the hypothesis that marine humic fluorescence is a potential proxy for iron solubility in the surface ocean. PARAFAC analysis revealed 4 components, two humic like substances and two protein-like. Overall none of the 4 components were significantly correlated with iron solubility, though humic-like components were weakly correlated with iron solubility in iron replete waters. Our analysis suggests that the ligands responsible for maintaining iron in solution in the euphotic zone are sourced from both remineralisation processes and specific ligands produced in response to iron stress and are not easily related to bulk CDOM properties. The humic fluorescence signal was sharply attenuated in surface waters presumably most likely due to photo bleaching, though there was only a weak correlation with the transient photo product H2O2, suggesting longer lifetimes in the photic zone for the fluorescent components identified here.
Key Points:
- humic-like components correlated with Fe solubility in iron repleted water
- ligands are sourced from remineralisation processes produced to Fe stress
- humic flu sharply attenuated in surface waters, but only weak corr. with H2O2

Document Type: Article
Additional Information: WOS:000316312700001
Keywords: Atlantic Ocean, Iron Speciation, Humic Fluorescence, Iron Solubility, Atlantic Meridional Transect, PARAFAC; DISSOLVED ORGANIC-MATTER; NORTH PACIFIC-OCEAN; IRON(III) HYDROXIDE SOLUBILITY; PARALLEL FACTOR-ANALYSIS; SURFACE WATERS; SOUTHERN-OCEAN; AMINO-ACIDS; HYDROGEN-PEROXIDE; NITROGEN-FIXATION; EUKARYOTIC PHYTOPLANKTON
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2012GB004427
ISSN: 0886-6236
Projects: SOPRAN, SOLAS, CVOO
Expeditions/Models/Experiments:
Date Deposited: 06 Dec 2012 14:08
Last Modified: 19 Mar 2018 09:06
URI: http://oceanrep.geomar.de/id/eprint/19599

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