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GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 21, GB4006, doi:10.1029/2006GB002907, 2007

A synthesis of global particle export from the surface ocean and cycling through the ocean interior and on the seafloor

John P. Dunne

NOAA Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA


Jorge L. Sarmiento

Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, New Jersey, USA


Anand Gnanadesikan

NOAA Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA


Abstract

We present a new synthesis of the oceanic cycles of organic carbon, silicon, and calcium carbonate. Our calculations are based on a series of algorithms starting with satellite-based primary production and continuing with conversion of primary production to sinking particle flux, penetration of particle flux to the deep sea, and accumulation in sediments. Regional and global budgets from this synthesis highlight the potential importance of shelves and near-shelf regions for carbon burial. While a high degree of uncertainty remains, this analysis suggests that shelves, less than 50 m water depths accounting for 2% of the total ocean area, may account for 48% of the global flux of organic carbon to the seafloor. Our estimates of organic carbon and nitrogen flux are in generally good agreement with previous work while our estimates for CaCO3 and SiO2 fluxes are lower than recent work. Interannual variability in particle export fluxes is found to be relatively small compared to intra-annual variability over large domains with the single exception of the dominating role of El Niño-Southern Oscillation variability in the central tropical Pacific. Comparison with available sediment-based syntheses of benthic remineralization and burial support the recent theory of mineral protection of organic carbon flux through the deep ocean, pointing to lithogenic material as an important carrier phase of organic carbon to the deep seafloor. This work suggests that models which exclude the role of lithogenic material would underestimate the penetration of POC to the deep seafloor by approximately 16–51% globally, and by a much larger fraction in areas with low productivity. Interestingly, atmospheric dust can only account for 31% of the total lithogenic flux and 42% of the lithogenically associated POC flux, implying that a majority of this material is riverine or directly erosional in origin.

Received 30 November 2006; accepted 12 July 2007; published 19 October 2007.

Keywords: carbon; export; production.

Index Terms: 4806 Oceanography: Biological and Chemical: Carbon cycling (0428); 4805 Oceanography: Biological and Chemical: Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912); 4845 Oceanography: Biological and Chemical: Nutrients and nutrient cycling (0470, 1050); 4863 Oceanography: Biological and Chemical: Sedimentation (1861).

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Citation: Dunne, J. P., J. L. Sarmiento, and A. Gnanadesikan (2007), A synthesis of global particle export from the surface ocean and cycling through the ocean interior and on the seafloor, Global Biogeochem. Cycles, 21, GB4006, doi:10.1029/2006GB002907.