Different flavours of oxygen help quantify seasonal variations of the biological carbon pump in the Celtic Sea

Seguro, Isabel ORCID: https://orcid.org/0000-0001-8453-0057, Marca, Alina D., Shutler, Jamie D. and Kaiser, Jan ORCID: https://orcid.org/0000-0002-1553-4043 (2023) Different flavours of oxygen help quantify seasonal variations of the biological carbon pump in the Celtic Sea. Frontiers in Marine Science, 10. ISSN 2296-7745

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Shelf seas represent only 10% of the World’s Ocean by area but support up to 30% of its primary production. There are few measurements of biological production at high spatial and temporal resolution in these physically and biologically dynamic systems. Here, we use dissolved oxygen to-argon (O 2/Ar) ratios and oxygen triple isotopes in O 2 ( 16O, 17O, 18O) to estimate net community production, N(O 2/Ar), and gross O 2 production, G( 17O), in summer and autumn 2014 and spring and summer 2015 in the Celtic Sea, as part of the UK Shelf-Sea Biogeochemistry Programme. Surface O 2/Ar concentration ratios were measured continuously using a shipboard membrane inlet mass spectrometer. Additional depth profiles of O 2/Ar concentration ratios, δ( 17O) and δ( 18O) were measured in discrete water samples from hydrocasts. The data were combined with wind-speed based gas exchange parameterisations to calculate biological air-sea oxygen fluxes. These fluxes were corrected for diapycnal diffusion, entrainment, production below the mixed layer, and changes over time to derive N(O 2/Ar) and G( 17O). The Celtic Sea showed the highest G( 17O) in summer 2014 (825 mmol m –2 d –1) and lowest during autumn 2014 (153 mmol m –2 d –1). N(O 2/Ar) was highest in spring 2015 (43 mmol m –2 d –1), followed by summer 2014 (42 mmol m –2 d –1), with a minimum in autumn 2014 (–24 mmol m –2 d –1). Dividing the survey region into three hydrographically distinct areas (Celtic Deep, Central Celtic Sea and Shelf Edge), we found that Celtic Deep and Shelf Edge had higher N(O 2/Ar) in summer (71 and 63 mmol m –2 d –1, respectively) than in spring (49 and 22 mmol m –2 d –1). This study shows regional differences in the metabolic balance within the same season, as well as higher net community production in summer than in spring in some areas and years. The seasonal patterns in biological production rates and the export efficiency (f-ratio) identified the importance of biology for supporting the Celtic Sea’s ability to act as a net CO 2 sink. Our measurements thus help improve our understanding of the biological carbon pump in temperate shelf seas.

Item Type: Article
Additional Information: Funding Information: IS was funded by UK Natural Environment Research Council (NERC) grant no. NE/L000172/1 and a Cefas CASE studentship. JS was supported by NERC grant nos. NE/K002058/1 and NE/K002511/1. JK was supported by NERC grant no. NE/K002473/1.
Uncontrolled Keywords: biological carbon pump,gross production,net community production,ar,oxygen triple isotopes,seasonality,shelf seas,water science and technology,environmental science (miscellaneous),ocean engineering,aquatic science,oceanography,global and planetary change,3* ,/dk/atira/pure/subjectarea/asjc/2300/2312
Faculty \ School: Faculty of Science > School of Environmental Sciences
University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 01 Jun 2023 10:30
Last Modified: 28 Jun 2023 09:32
URI: https://ueaeprints.uea.ac.uk/id/eprint/92241
DOI: 10.3389/fmars.2023.1037470


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