Seasonal iron depletion in a temperature shelf sea

Our study followed the seasonal cycling of soluble (SFe), colloidal (CFe), dissolved (DFe), total dissolvable (TDFe), labile particulate (LPFe), and total particulate (TPFe) iron in the Celtic Sea (NE Atlantic Ocean). Preferential uptake of SFe occurred during the spring bloom, preceding the removal...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Birchill, AJ, Milne, A, Woodward, EMS, Harris, C, Annett, A, Rusiecka, D, Achterberg, EP, Gledhill, M, Ussher, SJ, Worsfold, PJ, Geibert, W, Lohan, MC
Format: Article in Journal/Newspaper
Language:English
Published: 2017
Subjects:
Chemistry
Marine Sciences
Oceanography
Ross Sea
Online Access:http://plymsea.ac.uk/id/eprint/7922/
http://plymsea.ac.uk/id/eprint/7922/3/Birchill_et_al-2017-Geophysical_Research_Letters.pdf
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL073881
https://doi.org/10.1002/2017GL073881
Description
Summary:Our study followed the seasonal cycling of soluble (SFe), colloidal (CFe), dissolved (DFe), total dissolvable (TDFe), labile particulate (LPFe), and total particulate (TPFe) iron in the Celtic Sea (NE Atlantic Ocean). Preferential uptake of SFe occurred during the spring bloom, preceding the removal of CFe. Uptake and export of Fe during the spring bloom, coupled with a reduction in vertical exchange, led to Fe deplete surface waters (<0.2 nM DFe; 0.11 nM LPFe, 0.45 nM TDFe, and 1.84 nM TPFe) during summer stratification. Below the seasonal thermocline, DFe concentrations increased from spring to autumn, mirroring NO3− and consistent with supply from remineralized sinking organic material, and cycled independently of particulate Fe over seasonal timescales. These results demonstrate that summer Fe availability is comparable to the seasonally Fe limited Ross Sea shelf and therefore is likely low enough to affect phytoplankton growth and species composition.

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