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Marine Ecology Progress Series

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MEPS 611:31-44 (2019)  -  DOI:

Effects of microbial processes and CaCO3 dynamics on inorganic carbon cycling in snow-covered Arctic winter sea ice

Dorte Haubjerg Søgaard1,2,*, Jody W. Deming3, Lorenz Meire1,4, Søren Rysgaard1,2,5

1Greenland Climate Research Centre (C/O Greenland Institute of Natural Resources), Kivioq 2, PO Box 570, 3900 Nuuk, Greenland
2Arctic Research Centre, Department of Bioscience, Aarhus University, Ny Munkegade 116, building 1540, 8000 Aarhus C, Denmark
3School of Oceanography, University of Washington, Seattle, WA 98195, USA
4Royal Netherlands Institute for Sea Research, and Utrecht University, 4401 NT Yerseke, Netherlands
5Centre for Earth Observation Science, CHR Faculty of Environment Earth and Resources, University of Manitoba, 499 Wallace Building, Winnipeg, MB R3T 2N2, Canada
*Corresponding author:

ABSTRACT: Few combined measurements of primary and bacterial productivity exist for Arctic sea ice, particularly during winter, making it difficult to assess the relative importance of these microbial processes for carbon cycling in sea ice. Furthermore, the occurrence of calcium carbonate (CaCO3), though well-documented in sea ice, is poorly described for the overlying snow. To address these gaps, we investigated primary and bacterial productivity and carbon dynamics at 2 contrasting locations: (1) a landfast site, with thick snow-covered first-year sea ice, and (2) a polynya site, with thin snow-covered young (<1 wk) sea ice. Comparisons of bacterial carbon demand and primary production indicated net heterotrophy in the sea ice at both locations, with a net carbon consumption rate of 0.87 to 1.86 mg C m-2 d-1 derived from sea ice bacterial carbon demand of 0.93 to 2.00 mg C m-2 d-1 and gross primary production of 0.06 to 0.14 mg C m-2 d-1. As these microbial rates are very low, physical processes largely account for the observed CO2 depletion in the ice. High CaCO3 concentrations of 250 to 430 µmol kg-1 were measured in the snow covers which, though similar to concentrations in the underlying ice, are orders of magnitude higher than those reported from the few studies available on CaCO3 in snow. Together these results suggest that the role of biology in modulating inorganic carbon cycling in ice, which can be important in spring, is minor as compared to abiotic processes.

KEY WORDS: High Arctic · First-year sea ice · Polynya ice · Snow cover · Primary production · Bacterial production · CaCO3

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Cite this article as: Søgaard DH, Deming JW, Meire L, Rysgaard S (2019) Effects of microbial processes and CaCO3 dynamics on inorganic carbon cycling in snow-covered Arctic winter sea ice. Mar Ecol Prog Ser 611:31-44.

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