Southern Ocean controls of the vertical marine δ 13 C gradient – a modelling study
δ 13 C, the standardised 13 C ∕ 12 C ratio expressed in per mille, is a widely used ocean tracer to study changes in ocean circulation, water mass ventilation, atmospheric p CO 2 , and the biological carbon pump on timescales ranging from decades to tens of millions of years. δ 13 C data derived fro...
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ftdoajarticles:oai:doaj.org/article:834d02ac336342bfba6c1c9e9b30559f 2023-05-15T17:37:03+02:00 Southern Ocean controls of the vertical marine δ 13 C gradient – a modelling study A. L. Morée J. Schwinger C. Heinze 2018-12-01T00:00:00Z https://doi.org/10.5194/bg-15-7205-2018 https://doaj.org/article/834d02ac336342bfba6c1c9e9b30559f EN eng Copernicus Publications https://www.biogeosciences.net/15/7205/2018/bg-15-7205-2018.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-15-7205-2018 1726-4170 1726-4189 https://doaj.org/article/834d02ac336342bfba6c1c9e9b30559f Biogeosciences, Vol 15, Pp 7205-7223 (2018) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2018 ftdoajarticles https://doi.org/10.5194/bg-15-7205-2018 2022-12-31T01:50:10Z δ 13 C, the standardised 13 C ∕ 12 C ratio expressed in per mille, is a widely used ocean tracer to study changes in ocean circulation, water mass ventilation, atmospheric p CO 2 , and the biological carbon pump on timescales ranging from decades to tens of millions of years. δ 13 C data derived from ocean sediment core analysis provide information on δ 13 C of dissolved inorganic carbon and the vertical δ 13 C gradient (i.e. Δ δ 13 C) in past oceans. In order to correctly interpret δ 13 C and Δ δ 13 C variations, a good understanding is needed of the influence from ocean circulation, air–sea gas exchange and biological productivity on these variations. The Southern Ocean is a key region for these processes, and we show here that Δ δ 13 C in all ocean basins is sensitive to changes in the biogeochemical state of the Southern Ocean. We conduct a set of idealised sensitivity experiments with the ocean biogeochemistry general circulation model HAMOCC2s to explore the effect of biogeochemical state changes of the Southern and Global Ocean on atmospheric δ 13 C, p CO 2 , and marine δ 13 C and Δ δ 13 C. The experiments cover changes in air–sea gas exchange rates, particulate organic carbon sinking rates, sea ice cover, and nutrient uptake efficiency in an unchanged ocean circulation field. Our experiments show that global mean Δ δ 13 C varies by up to about ±0.35 ‰ around the pre-industrial model reference (1.2 ‰) in response to biogeochemical change. The amplitude of this sensitivity can be larger at smaller scales, as seen from a maximum sensitivity of about −0.6 ‰ on ocean basin scale. The ocean's oldest water (North Pacific) responds most to biological changes, the young deep water (North Atlantic) responds strongly to air–sea gas exchange changes, and the vertically well-mixed water (SO) has a low or even reversed Δ δ 13 C sensitivity compared to the other basins. This local Δ δ 13 C sensitivity depends on the local thermodynamic disequilibrium and the Δ δ 13 C sensitivity to local POC export production changes. ... Article in Journal/Newspaper North Atlantic Sea ice Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Pacific Biogeosciences 15 23 7205 7223 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 A. L. Morée J. Schwinger C. Heinze Southern Ocean controls of the vertical marine δ 13 C gradient – a modelling study |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
δ 13 C, the standardised 13 C ∕ 12 C ratio expressed in per mille, is a widely used ocean tracer to study changes in ocean circulation, water mass ventilation, atmospheric p CO 2 , and the biological carbon pump on timescales ranging from decades to tens of millions of years. δ 13 C data derived from ocean sediment core analysis provide information on δ 13 C of dissolved inorganic carbon and the vertical δ 13 C gradient (i.e. Δ δ 13 C) in past oceans. In order to correctly interpret δ 13 C and Δ δ 13 C variations, a good understanding is needed of the influence from ocean circulation, air–sea gas exchange and biological productivity on these variations. The Southern Ocean is a key region for these processes, and we show here that Δ δ 13 C in all ocean basins is sensitive to changes in the biogeochemical state of the Southern Ocean. We conduct a set of idealised sensitivity experiments with the ocean biogeochemistry general circulation model HAMOCC2s to explore the effect of biogeochemical state changes of the Southern and Global Ocean on atmospheric δ 13 C, p CO 2 , and marine δ 13 C and Δ δ 13 C. The experiments cover changes in air–sea gas exchange rates, particulate organic carbon sinking rates, sea ice cover, and nutrient uptake efficiency in an unchanged ocean circulation field. Our experiments show that global mean Δ δ 13 C varies by up to about ±0.35 ‰ around the pre-industrial model reference (1.2 ‰) in response to biogeochemical change. The amplitude of this sensitivity can be larger at smaller scales, as seen from a maximum sensitivity of about −0.6 ‰ on ocean basin scale. The ocean's oldest water (North Pacific) responds most to biological changes, the young deep water (North Atlantic) responds strongly to air–sea gas exchange changes, and the vertically well-mixed water (SO) has a low or even reversed Δ δ 13 C sensitivity compared to the other basins. This local Δ δ 13 C sensitivity depends on the local thermodynamic disequilibrium and the Δ δ 13 C sensitivity to local POC export production changes. ... |
format |
Article in Journal/Newspaper |
author |
A. L. Morée J. Schwinger C. Heinze |
author_facet |
A. L. Morée J. Schwinger C. Heinze |
author_sort |
A. L. Morée |
title |
Southern Ocean controls of the vertical marine δ 13 C gradient – a modelling study |
title_short |
Southern Ocean controls of the vertical marine δ 13 C gradient – a modelling study |
title_full |
Southern Ocean controls of the vertical marine δ 13 C gradient – a modelling study |
title_fullStr |
Southern Ocean controls of the vertical marine δ 13 C gradient – a modelling study |
title_full_unstemmed |
Southern Ocean controls of the vertical marine δ 13 C gradient – a modelling study |
title_sort |
southern ocean controls of the vertical marine δ 13 c gradient – a modelling study |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/bg-15-7205-2018 https://doaj.org/article/834d02ac336342bfba6c1c9e9b30559f |
geographic |
Southern Ocean Pacific |
geographic_facet |
Southern Ocean Pacific |
genre |
North Atlantic Sea ice Southern Ocean |
genre_facet |
North Atlantic Sea ice Southern Ocean |
op_source |
Biogeosciences, Vol 15, Pp 7205-7223 (2018) |
op_relation |
https://www.biogeosciences.net/15/7205/2018/bg-15-7205-2018.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-15-7205-2018 1726-4170 1726-4189 https://doaj.org/article/834d02ac336342bfba6c1c9e9b30559f |
op_doi |
https://doi.org/10.5194/bg-15-7205-2018 |
container_title |
Biogeosciences |
container_volume |
15 |
container_issue |
23 |
container_start_page |
7205 |
op_container_end_page |
7223 |
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1766136756950794240 |