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Biogeosciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/bg-2017-318
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
10 Aug 2017
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Biogeosciences (BG).
Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea
Jacoba Mol1, Helmuth Thomas1, Paul G. Myers2, Xianmin Hu2, and Alfonso Mucci3 1Department of Oceanography, Dalhousie University, Halifax, B3H 4R2, Canada
2Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, T6G 2E3, Canada
3Department of Earth and Planetary Sciences, McGill University, Montreal, H3A 0E8, Canada
Abstract. The Mackenzie Shelf in the southeastern Beaufort Sea is a region that has experienced large changes in the past several decades as warming, sea-ice loss, and increased river discharge have altered carbon cycling. Upwelling and downwelling events are common on the shelf, caused by strong, fluctuating along-shore winds, resulting in cross-shelf Ekman transport, and an alternating estuarine and anti-estuarine circulation. Downwelling carries inorganic carbon and other remineralization products off the shelf and into the deep basin for possible long-term storage in the world oceans. Upwelling carries dissolved inorganic carbon (DIC) and nutrient-rich waters from the Pacific-origin upper halocline layer (UHL) onto the shelf. Profiles of DIC and total alkalinity (TA) taken in August and September of 2014 are used to investigate the cycling of inorganic carbon on the Mackenzie Shelf. The along-shore transport of water and the cross-shelf transport of inorganic carbon are quantified using velocity field output from a simulation of the Arctic and Northern Hemisphere Atlantic (ANHA4) configuration of the Nucleus of European Modelling of the Ocean (NEMO) framework. A strong upwelling event prior to sampling on the Mackenzie Shelf is analyzed and the resulting influence on the carbonate system, including the saturation state of waters with respect to aragonite and pH, is investigated. TA and the oxygen isotope ratio of water (δ18O) are used to examine water-mass distributions in the study area and to investigate the influence of Pacific Water, Mackenzie River freshwater, and sea-ice melt on carbon dynamics and air-sea fluxes of carbon dioxide (CO2) in the surface mixed layer. Understanding carbon transfer in this seasonally dynamic environment is key to quantify the importance of Arctic shelf regions to the global carbon cycle and provide a basis for understanding how it will respond to the aforementioned climate-induced changes.

Citation: Mol, J., Thomas, H., Myers, P. G., Hu, X., and Mucci, A.: Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea, Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-318, in review, 2017.
Jacoba Mol et al.
Jacoba Mol et al.
Jacoba Mol et al.

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