Strong biological carbon uptake and carbonate chemistry associated with dense shelf water outflows in the Cape Darnley polynya, East Antarctica

Kan, Murakami; Daiki, Nomura; Gen, Hashida; Nakaoka, Shin-ichiro; Kitade, Yujiro; Hirano, Daisuke; Hirawake, Toru; Ohshima, Kay I.

Strong biological carbon uptake and carbonate chemistry associated with dense shelf water outflows in the Cape Darnley polynya, East Antarctica

Kan, Murakami; Daiki, Nomura; Gen, Hashida et al.

Marine Chemistry, 2020, 225, 103842

Permalink : https://hdl.handle.net/2115/86808

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アクセス権	open access
URI	https://hdl.handle.net/2115/86808
タイトル	Strong biological carbon uptake and carbonate chemistry associated with dense shelf water outflows in the Cape Darnley polynya, East Antarctica
著者	Kan, Murakami ; Daiki, Nomura ; Gen, Hashida ; Nakaoka, Shin-ichiro ; Kitade, Yujiro ; Hirano, Daisuke ; Hirawake, Toru ; Ohshima, Kay I.
著者名 Kan, Murakami
e-Rad_Researcher 70550739 著者名 Daiki, Nomura
e-Rad_Researcher 00280537 著者名 Gen, Hashida
著者名 Nakaoka, Shin-ichiro
e-Rad_Researcher 50281001 著者名 Kitade, Yujiro
著者名 Hirano, Daisuke
e-Rad_Researcher 70311165 著者名 Hirawake, Toru
e-Rad_Researcher 30185251 著者名 Ohshima, Kay I.
言語	英語
キーワード	Carbon dioxide
	Primary production
	Carbon transport
	Dense water formation
	Gas exchange
	Polynya
	Cape Darnley
	Southern Ocean
発行日	2020-09-10
出版者	Elsevier
収録物名	Marine Chemistry
巻(号)	225
ページ	103842
抄録	Formation of dense shelf water (DSW) in coastal polynyas (open water or thin sea-ice cover) in the sea-ice zone around Antarctica supplies Antarctic Bottom Water (AABW) through overflow down the continental slope. In coastal polynyas, atmospheric carbon dioxide (CO2) is absorbed by the ocean in the early spring because of active primary production, and DSW formation is an important process for transporting this carbon from the sea surface to the deep ocean. However, there have been few quantitative evaluations of carbon consumption by active primary production and transport in coastal polynyas. Here, we examined the carbon dynamics in the Cape Darnley polynya (CDP), East Antarctica during austral summer 2009, by using carbonate system parameters combined with oceanographic mooring data. The partial pressure of CO2 in the CDP surface water was lower than that of the atmosphere and the mean and standard deviation of sea−air CO2 flux was estimated as −6.5 ± 6.9 mmol C m−2 d−1 (a negative value indicates absorption of atmospheric CO2 by the ocean). Vertical profiles of dissolved inorganic carbon (DIC) concentration showed that concentrations in the bottom layer near the ocean floor were lower (by about 20 μmol kg−1) than those in the ambient water (e.g., modified Circumpolar Deep Water, mCDW). The low-DIC in the shelf water was maintained by the strong biological uptake of carbon imported from high-DIC mCDW within the water column. Therefore, low-DIC DSW overflowed down the continental slope, and low-DIC concentrations were maintained through an export pathway to the continental shelf. The annual production of dissolved organic carbon and particulate organic carbon on the shelf was estimated as 0.7 × 1011–1.5 × 1011 mol C using the data for the DIC of DSW and current velocity data from a mooring in the CDP. Our results provide quantitative estimates for the potential role of carbon consumption by the active primary production and carbon transport by dense water formation in Antarctic coastal polynyas.
資源タイプ	学術雑誌論文
出版タイプ	Accepted Manuscript
権利情報	Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
権利情報	© 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
PISSN	0304-4203
関連情報 (isVersionOf)	出版社版DOI https://doi.org/10.1016/j.marchem.2020.103842