Inorganic carbon system dynamics in landfast Arctic sea ice during the early-melt period
Brown, Kristina A.
Miller, Lisa A.
Mundy, C. J.
Tortell, Philippe D.
MetadataShow full item record
We present the results of a 6 week time series of carbonate system and stable isotope measurements investigating the effects of sea ice on air-sea CO2 exchange during the early melt period in the Canadian Arctic Archipelago. Our observations revealed significant changes in sea ice and sackhole brine carbonate system parameters that were associated with increasing temperatures and the buildup of chlorophyll a in bottom ice. The warming sea-ice column could be separated into distinct geochemical zones where biotic and abiotic processes exerted different influences on inorganic carbon and pCO2 distributions. In the bottom ice, biological carbon uptake maintained undersaturated pCO2 conditions throughout the time series, while pCO2 was supersaturated in the upper ice. Low CO2 permeability of the sea ice matrix and snow cover effectively impeded CO2 efflux to the atmosphere, despite a strong pCO2 gradient. Throughout the middle of the ice column, brine pCO2 decreased significantly with time and was tightly controlled by solubility, as sea ice temperature and in situ melt dilution increased. Once the influence of melt dilution was accounted for, both CaCO3 dissolution and seawater mixing were found to contribute alkalinity and dissolved inorganic carbon to brines, with the CaCO3 contribution driving brine pCO2 to values lower than predicted from melt-water dilution alone. This field study reveals a dynamic carbon system within the rapidly warming sea ice, prior to snow melt. We suggest that the early spring period drives the ice column toward pCO2 undersaturation, contributing to a weak atmospheric CO2 sink as the melt period advances.
Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 120 (2015): 3542-3566, doi:10.1002/2014JC010620.
Showing items related by title, author, creator and subject.
Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic : 14C characteristics of sedimentary carbon components and their environmental controls Feng, Xiaojuan; Gustafsson, Orjan; Holmes, Robert M.; Vonk, Jorien E.; van Dongen, Bart E.; Semiletov, Igor P.; Dudarev, Oleg V.; Yunker, Mark B.; Macdonald, Robie W.; Wacker, Lukas; Montlucon, Daniel B.; Eglinton, Timothy I. (John Wiley & Sons, 2015-11-02)Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. ...
Carbon dynamics in the western Arctic Ocean : insights from full-depth carbon isotope profiles of DIC, DOC, and POC Griffith, David R.; McNichol, Ann P.; Xu, Li; McLaughlin, Fiona A.; Macdonald, Robie W.; Brown, Kristina A.; Eglinton, Timothy I. (Copernicus Publications on behalf of the European Geosciences Union, 2012-03-28)Arctic warming is projected to continue throughout the coming century. Yet, our currently limited understanding of the Arctic Ocean carbon cycle hinders our ability to predict how changing conditions will affect local ...
Hilton, Robert G.; Galy, Valier; Gaillardet, Jerome; Dellinger, Mathieu; Bryant, Charlotte; O'Regan, Matt; Grocke, Darren R.; Coxall, Helen; Bouchez, Julien; Calmels, Damien (2015-05-12)Soils of the northern high latitudes store carbon over millennial timescales (103 yrs) and contain approximately double the carbon stock of the atmosphere1-3. Warming and associated permafrost thaw can expose soil organic ...