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Macro-nutrient concentrations in Antarctic pack ice: overall patterns and overlooked processes

Citation

Fripiat, F and Meiners, KM and Vancoppenolle, M and Papadimitriou, S and Thomas, DN and Ackley, SF and Arrigo, KR and Carnat, G and Cozzi, S and Delille, B and Dieckmann, GS and Dunbar, RB and Fransson, A and Kattner, G and Kennedy, H and Lannuzel, D and Munro, DR and Nomura, D and Rintala, JM and Schoemann, V and Stefels, J and Steiner, N and Tison, J-L, Macro-nutrient concentrations in Antarctic pack ice: overall patterns and overlooked processes, Elementa, 5 Article 13. ISSN 2325-1026 (2017) [Refereed Article]


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Copyright 2017 the Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

DOI: doi:10.1525/elementa.217

Abstract

Antarctic pack ice is inhabited by a diverse and active microbial community reliant on nutrients for growth. Seeking patterns and overlooked processes, we performed a large-scale compilation of macro-nutrient data (hereafter termed nutrients) in Antarctic pack ice (306 ice-cores collected from 19 research cruises). Dissolved inorganic nitrogen and silicic acid concentrations change with time, as expected from a seasonally productive ecosystem. In winter, salinity-normalized nitrate and silicic acid concentrations (C*) in sea ice are close to seawater concentrations (Cw), indicating little or no biological activity. In spring, nitrate and silicic acid concentrations become partially depleted with respect to seawater (C* < Cw), commensurate with the seasonal build-up of ice microalgae promoted by increased insolation. Stronger and earlier nitrate than silicic acid consumption suggests that a significant fraction of the primary productivity in sea ice is sustained by flagellates. By both consuming and producing ammonium and nitrite, the microbial community maintains these nutrients at relatively low concentrations in spring. With the decrease in insolation beginning in late summer, dissolved inorganic nitrogen and silicic acid concentrations increase, indicating imbalance between their production (increasing or unchanged) and consumption (decreasing) in sea ice. Unlike the depleted concentrations of both nitrate and silicic acid from spring to summer, phosphate accumulates in sea ice (C* > Cw). The phosphate excess could be explained by a greater allocation to phosphorus-rich biomolecules during ice algal blooms coupled with convective loss of excess dissolved nitrogen, preferential remineralization of phosphorus, and/or phosphate adsorption onto metal-organic complexes. Ammonium also appears to be efficiently adsorbed onto organic matter, with likely consequences to nitrogen mobility and availability. This dataset supports the view that the sea ice microbial community is highly efficient at processing nutrients but with a dynamic quite different from that in oceanic surface waters calling for focused future investigations.

Item Details

Item Type:Refereed Article
Keywords:sea ice, Antarctica, nutrients
Research Division:Chemical Sciences
Research Group:Inorganic Chemistry
Research Field:Inorganic Chemistry not elsewhere classified
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Antarctic and Sub-Antarctic Flora, Fauna and Biodiversity
UTAS Author:Meiners, KM (Dr Klaus Meiners)
UTAS Author:Lannuzel, D (Associate Professor Delphine Lannuzel)
ID Code:123617
Year Published:2017
Web of Science® Times Cited:13
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2018-01-15
Last Modified:2018-04-23
Downloads:41 View Download Statistics

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