A revised global estimate of dissolved iron fluxes from marine sediments.

Dale, Andrew W. , Nickelsen, Levin, Scholz, Florian, Hensen, Christian , Oschlies, Andreas and Wallmann, Klaus (2015) A revised global estimate of dissolved iron fluxes from marine sediments. Open Access Global Biogeochemical Cycles, 29 (5). pp. 691-707. DOI 10.1002/2014GB005017.

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Literature data on benthic dissolved iron (DFe) fluxes (µmol m−2 d−1), bottom water oxygen concentrations (O2BW, μM), and sedimentary carbon oxidation rates (COX, mmol m−2 d−1) from water depths ranging from 80 to 3700 m were assembled. The data were analyzed with a diagenetic iron model to derive an empirical function for predicting benthic DFe fluxes: inline image where γ (= 170 µmol m−2 d−1) is the maximum flux for sediments at steady state located away from river mouths. This simple function unifies previous observations that COX and O2BW are important controls on DFe fluxes. Upscaling predicts a global DFe flux from continental margin sediments of 109 ± 55 Gmol yr−1, of which 72 Gmol yr−1 is contributed by the shelf (<200 m) and 37 Gmol yr−1 by slope sediments (200–2000 m). The predicted deep-sea flux (>2000 m) of 41 ± 21 Gmol yr−1 is unsupported by empirical data. Previous estimates of benthic DFe fluxes derived using global iron models are far lower (approximately 10–30 Gmol yr−1). This can be attributed to (i) inadequate treatment of the role of oxygen on benthic DFe fluxes and (ii) improper consideration of continental shelf processes due to coarse spatial resolution. Globally averaged DFe concentrations in surface waters simulated with the intermediate-complexity University of Victoria Earth System Climate Model were a factor of 2 higher with the new function. We conclude that (i) the DFe flux from marginal sediments has been underestimated in the marine iron cycle and (ii) iron scavenging in the water column is more intense than currently presumed.

Document Type: Article
Additional Information: WOS:000356383700012
Keywords: Iron cycle, benthic flux, diagenetic model, Earth System model,
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence > FO-R05
OceanRep > SFB 754
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/2014GB005017
ISSN: 0886-6236
Projects: SFB754, BICYCLE, Future Ocean
Date Deposited: 13 Jul 2015 10:23
Last Modified: 23 Sep 2019 21:40
URI: http://oceanrep.geomar.de/id/eprint/29223

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