Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean

Marsay, Chris M., Sanders, Richard J., Henson, Stephanie A., Pabortsava, Katsiaryna, Achterberg, Eric P. and Lampitt, Richard S. (2015) Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean Proceedings of the National Academy of Sciences of the United States of America, 112 (4). pp. 1089-1094. DOI 10.1073/pnas.1415311112.

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The biological carbon pump, which transports particulate organic carbon (POC) from the surface to the deep ocean, plays an important role in regulating atmospheric carbon dioxide (CO2) concentrations. We know very little about geographical variability in the remineralization depth of this sinking material and less about what controls such variability. Here we present previously unpublished profiles of mesopelagic POC flux derived from neutrally buoyant sediment traps deployed in the North Atlantic, from which we calculate the remineralization length scale for each site. Combining these results with corresponding data from the North Pacific, we show that the observed variability in attenuation of vertical POC flux can largely be explained by temperature, with shallower remineralization occurring in warmer waters. This is seemingly inconsistent with conclusions drawn from earlier analyses of deep-sea sediment trap and export flux data, which suggest lowest transfer efficiency at high latitudes. However, the two patterns can be reconciled by considering relatively intense remineralization of a labile fraction of material in warm waters, followed by efficient downward transfer of the remaining refractory fraction, while in cold environments, a larger labile fraction undergoes slower remineralization that continues over a longer length scale. Based on the observed relationship, future increases in ocean temperature will likely lead to shallower remineralization of POC and hence reduced storage of CO2 by the ocean.

Document Type: Article
Additional Information: WOS:000348417000044
Keywords: Biological carbon pump; Mesopelagic; Particulate organic carbon; Remineralization
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
Refereed: Yes
DOI etc.: 10.1073/pnas.1415311112
ISSN: 0027-8424
Projects: Future Ocean
Date Deposited: 10 Feb 2015 09:40
Last Modified: 19 Dec 2017 12:43

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