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Incorporation of iron and organic matter into young Antarctic sea ice during its initial growth stages

Citation

Janssens, J and Meiners, KM and Tison, J-L and Dieckmann, G and Delille, B and Lannuzel, D, Incorporation of iron and organic matter into young Antarctic sea ice during its initial growth stages, Elementa, 4 Article 000123. ISSN 2325-1026 (2016) [Refereed Article]


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Copyright 2016 Janssens et al. Licensed under Creative Commons Attribution 3.0 United States (CC BY 3.0 US) https://creativecommons.org/licenses/by/3.0/us/

DOI: doi:10.12952/journal.elementa.000123

Abstract

This study reports concentrations of iron (Fe) and organic matter in young Antarctic pack ice and during its initial growth stages in situ. Although the importance of sea ice as an Fe reservoir for oceanic waters of the Southern Ocean has been clearly established, the processes leading to the enrichment of Fe in sea ice have yet to be investigated and quantified. We conducted two in situ sea-ice growth experiments during a winter cruise in the Weddell Sea. Our aim was to improve the understanding of the processes responsible for the accumulation of dissolved Fe (DFe) and particulate Fe (PFe) in sea ice, and of particulate organic carbon and nitrogen, dissolved organic carbon, extracellular polymeric substances, inorganic macro-nutrients (silicic acid, nitrate and nitrite, phosphate and ammonium), chlorophyll a and bacteria. Enrichment indices, calculated for natural young ice and ice newly formed in situ, indicate that during Antarctic winter all of the measured forms of particulate matter were enriched in sea ice compared to underlying seawater, and that enrichment started from the initial stages of sea-ice formation. Some dissolved material (DFe and ammonium) was also enriched in the ice but at lower enrichment indices than the particulate phase, suggesting that size is a key factor for the incorporation of impurities in sea ice. Low chlorophyll a concentrations and the fit of the macro-nutrients (with the exception of ammonium) with their theoretical dilution lines indicated low biological activity in the ice. From these and additional results we conclude that physical processes are the dominant mechanisms leading to the enrichment of DFe, PFe, organic matter and bacteria in young sea ice, and that PFe and DFe are decoupled during sea-ice formation. Our study thus provides unique quantitative insight into the initial incorporation of impurities, in particular DFe and PFe, into Antarctic sea ice.

Item Details

Item Type:Refereed Article
Keywords:sea ice, biogeochemistry, modelling
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical Oceanography
Objective Division:Environment
Objective Group:Other Environment
Objective Field:Environment not elsewhere classified
UTAS Author:Janssens, J (Miss Julie Janssens)
UTAS Author:Meiners, KM (Dr Klaus Meiners)
UTAS Author:Lannuzel, D (Associate Professor Delphine Lannuzel)
ID Code:111805
Year Published:2016
Web of Science® Times Cited:7
Deposited By:Oceans and Cryosphere
Deposited On:2016-10-07
Last Modified:2017-11-17
Downloads:100 View Download Statistics

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