Closing the global marine Ra-226 budget reveals the biological pump as a dominant removal flux in the upper ocean

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Date
2022-06-10
Authors
Xu, Bochao
Cardenas, M. Bayani
Santos, Isaac R.
Burnett, William C.
Charette, Matthew A.
Rodellas, Valenti
Li, Sanzhong
Lian, Ergang
Yu, Zhigang
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DOI
10.1029/2022GL098087
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Keywords
Particle scavenging
Submarine groundwater discharge
Siliceous algae
Global ocean
Abstract
Radium isotopes are powerful proxies in oceanography and hydrology. Radium mass balance models, including assessments of submarine groundwater discharge (SGD), often overlook particle scavenging (PS) as a pathway for dissolved radium removal from the world ocean. Here, we build a global ocean 226Ra mass balance model and reevaluate the potential importance of PS. We find that PS is the major 226Ra sink for the upper ocean, removing about 96% of the total input from various sources. Aside from vertical exchange with the lower ocean, SGD is the largest 226Ra source into the upper ocean. The biological pump transfers particles to the deep ocean, resulting in a major but often overlooked impact on the global 226Ra marine budget. Our findings suggest that radium mass balance models should consider PS in systems with high siliceous algae production and export fluxes and long water residence times to prevent underestimation of large-scale SGD fluxes.
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Author Posting. © American Geophysical Union, 2022. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 49(12), (2022): e2022GL098087, https://doi.org/10.1029/2022GL098087.
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Xu, B., Cardenas, M. B., Santos, I. R., Burnett, W. C., Charette, M. A., Rodellas, V., Li, S., Lian, E., & Yu, Z. (2022). Closing the global marine Ra-226 budget reveals the biological pump as a dominant removal flux in the upper ocean. Geophysical Research Letters, 49(12), e2022GL098087.
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