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Slow-sinking particulate organic carbon in the Atlantic Ocean: magnitude, flux, and potential controls


Baker, CA and Henson, SA and Cavan, EL and Giering, SLC and Yool, A and Gehlen, M and Belcher, A and Riley, JS and Smith, HEK and Sanders, R, Slow-sinking particulate organic carbon in the Atlantic Ocean: magnitude, flux, and potential controls, Global Biogeochemical Cycles, 31, (7) pp. 1051-1065. ISSN 0886-6236 (2017) [Refereed Article]


Copyright Statement

Copyright 2017 the authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

DOI: doi:10.1002/2017GB005638


The remineralization depth of particulate organic carbon (POC) fluxes exported from the surface ocean exerts a major control over atmospheric CO₂ levels. According to a long-held paradigm most of the POC exported to depth is associated with large particles. However, recent lines of evidence suggest that slow-sinking POC (SSPOC) may be an important contributor to this flux. Here we assess the circumstances under which this occurs. Our study uses samples collected using the Marine Snow Catcher throughout the Atlantic Ocean, from high latitudes to midlatitudes. We find median SSPOC concentrations of 5.5 μg L−1, 13 times smaller than suspended POC concentrations and 75 times higher than median fast-sinking POC (FSPOC) concentrations (0.07 μg L−1). Export fluxes of SSPOC generally exceed FSPOC flux, with the exception being during a spring bloom sampled in the Southern Ocean. In the Southern Ocean SSPOC fluxes often increase with depth relative to FSPOC flux, likely due to midwater fragmentation of FSPOC, a process which may contribute to shallow mineralization of POC and hence to reduced carbon storage. Biogeochemical models do not generally reproduce this behavior, meaning that they likely overestimate long-term ocean carbon storage.

Item Details

Item Type:Refereed Article
Keywords:carbon cycle, oceans
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Environmental Management
Objective Group:Fresh, ground and surface water systems and management
Objective Field:Measurement and assessment of freshwater quality (incl. physical and chemical conditions of water)
UTAS Author:Cavan, EL (Dr Emma Cavan)
ID Code:124346
Year Published:2017
Web of Science® Times Cited:28
Deposited By:Ecology and Biodiversity
Deposited On:2018-02-19
Last Modified:2018-05-09
Downloads:63 View Download Statistics

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