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Published on: July 14, 2023
New production regulates export stoichiometry in the ocean
Tobias Tamelander1, Marit Reigstad, Kalle Olli
1Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway. tobtam@gmail.com
Ocean carbon export is higher than previously estimated. Particulate organic carbon to nitrogen ratios in the Arctic Ocean exceed Redfield ratios, suggesting a 10-30% increase in carbon export and improving global carbon cycle models.
Area of Science:
- Oceanography
- Biogeochemistry
- Marine Carbon Cycle
Background:
- The biological carbon pump is critical for regulating atmospheric CO2.
- Accurate estimation of carbon export from surface to deep ocean is essential for climate models.
- Particulate organic carbon (POC) and nitrogen (PON) stoichiometry influences carbon export estimates.
Purpose of the Study:
- To investigate the POC:PON ratio in the European Arctic Ocean.
- To assess the accuracy of the Redfield ratio in carbon export models.
- To understand regional variations in export stoichiometry and their impact on carbon export estimates.
Main Methods:
- Analysis of over 400 vertical flux observations of POC and PON.
- Comparison of observed POC:PON ratios with the Redfield atomic ratio (6.625).
- Regional analysis of POC:PON ratios in relation to new production.
Main Results:
- Exported POC:PON ratios consistently exceeded the Redfield ratio in the European Arctic.
- The deep Central Arctic Ocean showed the largest deviations, with a mean ratio of 9.7.
- Spatially integrated POC export in the European Arctic was 10-30% higher than Redfield-based estimates.
- Export stoichiometry varied regionally, being highest in oligotrophic areas like the Central Arctic and subtropical gyres.
Conclusions:
- The assumption of constant C:N stoichiometry is not valid for the Arctic Ocean.
- Accounting for variable export stoichiometry improves regional carbon export predictions.
- More accurate modeling of the oceans' contribution to the global carbon cycle is achievable.
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