Shallow particulate organic carbon regeneration in the South Pacific Ocean.

Autor:	Pavia FJ; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964; fpavia@ldeo.columbia.edu.; Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027., Anderson RF; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964.; Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027., Lam PJ; Department of Ocean Sciences, University of California, Santa Cruz, CA 95064., Cael BB; Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI 96822.; Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI 96822., Vivancos SM; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964.; Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027., Fleisher MQ; Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027., Lu Y; Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455., Zhang P; Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455., Cheng H; Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455.; Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710054, China., Edwards RL; Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2019 May 14; Vol. 116 (20), pp. 9753-9758. Date of Electronic Publication: 2019 Apr 29.
DOI:	10.1073/pnas.1901863116
Abstrakt:	Particulate organic carbon (POC) produced in the surface ocean sinks through the water column and is respired at depth, acting as a primary vector sequestering carbon in the abyssal ocean. Atmospheric carbon dioxide levels are sensitive to the length (depth) scale over which respiration converts POC back to inorganic carbon, because shallower waters exchange with the atmosphere more rapidly than deeper ones. However, estimates of this carbon regeneration length scale and its spatiotemporal variability are limited, hindering the ability to characterize its sensitivity to environmental conditions. Here, we present a zonal section of POC fluxes at high vertical and spatial resolution from the GEOTRACES GP16 transect in the eastern tropical South Pacific, based on normalization to the radiogenic thorium isotope 230 Th. We find shallower carbon regeneration length scales than previous estimates for the oligotrophic South Pacific gyre, indicating less efficient carbon transfer to the deep ocean. Carbon regeneration is strongly inhibited within suboxic waters near the Peru coast. Canonical Martin curve power laws inadequately capture POC flux profiles at suboxic stations. We instead fit these profiles using an exponential function with flux preserved at depth, finding shallow regeneration but high POC sequestration below 1,000 m. Both regeneration length scales and POC flux at depth closely track the depths at which oxygen concentrations approach zero. Our findings imply that climate warming will result in reduced ocean carbon storage due to expanding oligotrophic gyres, but opposing effects on ocean carbon storage from expanding suboxic waters will require modeling and future work to disentangle. Competing Interests: The authors declare no conflict of interest.
Databáze:	MEDLINE
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