The overlooked contribution of the seasonal mixed layer pump to carbon export in low-latitude oceans
Creators
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1.
Xiamen University
- 2. Advanced Institute for Marine Studies, Fujian Ocean Innovation Center, Xiamen, China
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3.
Duke University
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4.
Laboratoire des Sciences de l'Environnement Marin
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5.
California Institute of Technology
Abstract
The seasonal mixed layer pump (MLP) is an important pathway transporting organic carbon from the upper ocean to the ocean interior. While the MLP’s export role has been well-studied in high latitudes, its contribution in low latitudes remains uncertain. Here, we quantify the seasonal MLP-driven carbon export (EMLP) in low-latitude oceans using data from 26 biogeochemical profiling floats. Our analysis reveals that EMLP ranges from −0.9 to 7.6 g C m−2 yr−1, contributing up to 53% of carbon export in certain areas. We find the relative positions of the mixed layer depth, euphotic depth, and nitracline depth regulate EMLP strength in low-latitude oceans. Global extrapolation of these observations across low-latitude oceans yields a total EMLP of 0.07 ± 0.02 Pg C yr−1, 75% higher than previous estimates, underscoring the previously underestimated role of the seasonal MLP in low-latitude oceans. These results reveal the controlling mechanisms of low-latitude seasonal MLP and highlight its disproportionately important role in regional ecosystems, particularly in oligotrophic oceans where carbon export pathways are limited.
Copyright and License
© The Author(s) 2025. This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Acknowledgement
B.H. and X.L. are supported by the National Natural Science Foundation of China (Nos. 42130401, 42141002, 42421004). C.X. is supported by the China Scholarship Council to study at Duke University as a joint PhD student (No. 202306310164). A.T. is supported by the Resnick Sustainability Institute at the California Institute of Technology and the Ginkgo Foundation.
Data Availability
Public floats data used in this study are downloaded from the Global Data Assembly Centers (ftp://usgodae.org/pub/outgoing/argo). The monthly remotely-sensed NPP is downloaded from the Ocean Productivity website (http://sites.science.oregonstate.edu/ocean.productivity). The weekly mixed layer depth and sea surface Chl a are downloaded from the E.U. Copernicus Marine Environment Monitoring Service (https://doi.org/10.48670/moi-00052 and https://doi.org/10.48670/moi-00046). Climatological nitrate data are downloaded from the World Ocean Atlas 2023. All data used in this study are available from Zenodo at https://zenodo.org/records/17114326.
Code Availability
All codes are available from Zenodo at https://zenodo.org/records/17114326.
Supplemental Material
Files
s41467-025-65710-2.pdf
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Additional details
Identifiers
- PMID
- 41309629
- PMCID
- PMC12660330
Related works
- Describes
- Journal Article: https://rdcu.be/eSPkY (ReadCube)
- Journal Article: 41309629 (PMID)
- Journal Article: PMC12660330 (PMCID)
- Is supplemented by
- Dataset: https://zenodo.org/records/17114326 (URL)
Funding
- National Natural Science Foundation of China
- 42130401
- National Natural Science Foundation of China
- 42141002
- National Natural Science Foundation of China
- 42421004
- China Scholarship Council
- 202306310164
- California Institute of Technology
- Resnick Sustainability Institute -
Dates
- Submitted
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2025-05-20
- Accepted
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2025-10-21