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

Elementa: Science of the Anthropocene

Gauthier Carnat¹  Klaus M. Meiners²  David R. Munro³  Stathys Papadimitriou⁴  Gerhard Kattner⁵  Daiki Nomura⁵  Martin Vancoppenolle⁶  Stephen F. Ackley⁷  Janne-Markus Rintala⁸  Kevin R. Arrigo⁸  Robert B. Dunbar⁹  Nadja Steiner^1,10  Jean-Louis Tison^1,11  Delphine Lannuzel^1,12  David N. Thomas^1,13  Bruno Delille^1,14  Hilary Kennedy^1,14  Jacqueline Stefels^1,15  Véronique Schoemann^1,16  Stefano Cozzi^1,17  Gerhard S. Dieckmann^1,18  Agneta Fransson^1,19  François Fripiat^2,20 

[1] and Finnish Environment Institute (SYKE), Marine Research Centre, Helsinki,;and Max Planck Institute for Chemistry, Mainz;and University of Gothenburg, Department of Earth Sciences, Göteborg;and University of Tasmania, Antarctic Climate and Ecosystems Cooperative Research Centre, Hobart, Tasmania,;Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven;Australian Antarctic Division, Department of the Environment and Energy, Kingston, Tasmania;Bangor University, School of Ocean Sciences, Menai Bridge, Anglesey,;Bangor University, School of Ocean Sciences, Menai Bridge, Anglesey;CNR-ISMAR, Istituto di Scienze Marine, Trieste;Faculty of Fisheries Science, Hokkaido University, Hakodate;Finnish Environment Institute (SYKE), Marine Research Centre, Helsinki;Norwegian Polar Institute, Fram Centre, Tromsø, Norway;Sorbonne Universités (UPMC Paris 6), LOCEAN-IPSL, CNRS/IRD/MNHN, Paris,;Stanford University, Department of Earth System Science, Stanford, California;University of Colorado Boulder, Department of Atmospheric and Oceanic Sciences and Institute of Arctic and Alpine Research, Boulder, Colorado;University of Tasmania, Institute for Marine and Antarctic Studies, Hobart, Tasmania;University of Texas at San Antonio, Snow and Ice Geophysics Laboratory, Geol. Sciences Dept, San Antonio, Texas,;Université Libre de Bruxelles, Laboratoire de Glaciologie, Brussels;Université de Liège, Unité d’Océanographie Chimique, MARE, Liège;Vrije Universiteit Brussel, Analytical, Environmental, and Geo-Chemistry Department, Brussels, Belgium;

关键词: Nutrients;    sea ice;    Antarctica;   

DOI  :  10.1525/elementa.217

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown