Pacific carbon cycling constrained by organic matter size, age and composition relationships

ABSTRACT Marine organic matter is one of Earth’s largest actively cycling reservoirs of organic carbon and nitrogen1,2. The processes controlling organic matter production and removal are

important for carbon and nitrogen biogeochemical cycles, which regulate climate. However, the many possible cycling mechanisms have hindered our ability to quantify marine organic matter

transformation, degradation and turnover rates3,4. Here we analyse existing and new measurements of the carbon:nitrogen ratio and radiocarbon age of organic matter spanning sizes from large

particulate organic matter to small dissolved organic molecules. We find that organic matter size is negatively correlated with radiocarbon age and carbon:nitrogen ratios in coastal, surface

and deep waters of the Pacific Ocean. Our measurements suggest that organic matter is increasingly chemically degraded as it decreases in size, and that small particles and molecules

persist in the ocean longer than their larger counterparts. Based on these correlations, we estimate the production rates of small, biologically recalcitrant dissolved organic matter

molecules at 0.11–0.14 Gt of carbon and about 0.005 Gt of nitrogen per year in the deep ocean. Our results suggest that the preferential remineralization of large over small particles and

molecules is a key process governing organic matter cycling and deep ocean carbon storage. Access through your institution Buy or subscribe This is a preview of subscription content, access

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THE OCEAN’S TWILIGHT ZONE Article Open access 27 April 2023 NEOGENE BURIAL OF ORGANIC CARBON IN THE GLOBAL OCEAN Article 04 January 2023 PLANKTONIC FORAMINIFERA ORGANIC CARBON ISOTOPES AS

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Google Scholar  Download references ACKNOWLEDGEMENTS We gratefully acknowledge B. Phillips, the staff of the Granite Canyon Marine Pollution Studies Laboratory (GCMPSL) and the Natural

Energy Laboratory of Hawaii Authority (NELHA) for providing facilities capable of large-volume seawater DOM and suspended POM isolations. K. Okimura, J. Walker, L. Roland, K. Walker, G. V. 

Reixach, and M. Calleja (UC Santa Cruz) aided with fieldwork and sample collection. S. Griffin (UCI) and P. Zermeno (LLNL) aided with sample analysis. F. Primeau (UCI) aided with error

analysis and Matlab scripts. This work was funded by the Friends of Long Marine Lab Student Research Awards (to B.D.W.), the UC Santa Cruz STEPS Institute for Innovation in Environmental

Research (to B.D.W.), the UC Santa Cruz Center for the Dynamics and Evolution of the Land-Sea Interface (to B.D.W.), the Earl H. Myers and Ethel M. Myers Oceanographic and Marine Biology

Trust (to B.D.W.), the UC Santa Cruz Institute of Geophysics and Planetary Physics (to B.D.W. and M.D.M.), NSF OCE-1358041 and NSF OCE-0623622 (M.D.M.) and NSF ARC-1022716 (E.R.M.D.). A

portion of this work was performed under the auspices of the US Department of Energy (contract W-7405-Eng-48 and DE-AC52-07NA27344) and a Keck Carbon Cycle AMS Laboratory Postdoctoral

Scholarship (B.D.W.). AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Earth System Science, University of California, Irvine, 2212 Croul Hall, Irvine, California 92697-3100, USA

Brett D. Walker & Ellen R. M. Druffel * Stony Brook University, School of Marine and Atmospheric Sciences, CH123, Stony Brook, New York 11794-5000, USA Steven R. Beaupré * Department of

Ocean Science, University of California, Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA Thomas P. Guilderson & Matthew D. McCarthy * Lawrence Livermore National

Laboratory, Center for Accelerator Mass Spectrometry (CAMS), LLNL-L397, 7000 East Avenue, Livermore, California 94551, USA Thomas P. Guilderson Authors * Brett D. Walker View author

publications You can also search for this author inPubMed Google Scholar * Steven R. Beaupré View author publications You can also search for this author inPubMed Google Scholar * Thomas P.

Guilderson View author publications You can also search for this author inPubMed Google Scholar * Matthew D. McCarthy View author publications You can also search for this author inPubMed 

Google Scholar * Ellen R. M. Druffel View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS B.D.W. conceived the research; B.D.W., S.R.B., T.P.G.,

M.D.M. and E.R.M.D. performed research; S.R.B., T.P.G., and E.R.M.D. contributed new reagents/analytical tools and models; B.D.W., S.R.B., T.P.G., E.R.M.D. and M.D.M. analysed data; B.D.W.

wrote the paper with inputs from S.R.B., T.P.G., M.D.M. and E.R.M.D. CORRESPONDING AUTHOR Correspondence to Brett D. Walker. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no

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THIS ARTICLE CITE THIS ARTICLE Walker, B., Beaupré, S., Guilderson, T. _et al._ Pacific carbon cycling constrained by organic matter size, age and composition relationships. _Nature Geosci_

9, 888–891 (2016). https://doi.org/10.1038/ngeo2830 Download citation * Received: 27 June 2016 * Accepted: 30 September 2016 * Published: 14 November 2016 * Issue Date: December 2016 * DOI:

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