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Riverine export of aged terrestrial organic matter to the North Atlantic Ocean

Nature volume 409, pages 497500 (25 January 2001) | Download Citation



Global riverine discharge of organic matter represents a substantial source of terrestrial dissolved and particulate organic carbon to the oceans1,2. This input from rivers is, by itself, more than large enough to account for the apparent steady-state replacement times of 4,00–6,000 yr for oceanic dissolved organic carbon3,4,5. But paradoxically, terrestrial organic matter, derived from land plants, is not detected in seawater and sediments in quantities that correspond to its inputs6,7,8. Here we present natural 14C and 13C data from four rivers that discharge to the western North Atlantic Ocean and find that these rivers are sources of old (14C-depleted) and young (14C-enriched) terrestrial dissolved organic carbon, and of predominantly old terrestrial particulate organic carbon. These findings contrast with limited earlier data9 that suggested terrestrial organic matter transported by rivers might be generally enriched in 14C from nuclear testing, and hence newly produced. We also find that much of the young dissolved organic carbon can be selectively degraded over the residence times of river and coastal waters, leaving an even older and more refractory component for oceanic export. Thus, pre-ageing and degradation may alter significantly the structure, distributions and quantities of terrestrial organic matter before its delivery to the oceans.

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We thank J. Cole, N. Caraco and C. Hopkinson for help in collecting samples from the Hudson and Parker rivers; D. Wolgast for assistance in oxidizing DOC samples; M. Kashgarian, J. Southon and B. Frantz for 14C analyses at the Center for AMS at Lawrence Livermore National Laboratory (LLNL); E. Druffel and S. Griffin for analysing the Amazon POC sample; J. Hobbie for comments on the manuscript; and E. Franks for δ13C analyses at Woods Hole Oceanographic Institution. This work was supported by the Ocean Margins Program of the US Department of Energy, the Chemical Oceanography and Long-Term Ecological Research Programs of the US NSF, and the Center for AMS at LLNL.

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    • Peter A. Raymond

    Present address: Marine Biological Laboratory, Ecosystems Center, Woods Hole, Massachusetts 02543, USA


  1. *School of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA

    • Peter A. Raymond
    •  & James E. Bauer


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Correspondence to Peter A. Raymond.

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