American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 487044 bytes)    Cited by

GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 21, GB4011, doi:10.1029/2007GB002934, 2007

Flux and age of dissolved organic carbon exported to the Arctic Ocean: A carbon isotopic study of the five largest arctic rivers

Peter A. Raymond

Yale School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA


J. W. McClelland

University of Texas at Austin, Port Aransas, Texas, USA


R. M. Holmes

Woods Hole Research Center, Falmouth, Massachusetts, USA


A. V. Zhulidov

South Russian Regional Centre for Preparation and Implementation of International Projects, Rostov-on-Don, Russia


K. Mull

Yale School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA


B. J. Peterson

Marine Biological Laboratory, Woods Hole, Massachusetts, USA


R. G. Striegl

U.S. Geological Survey, Denver, Colorado, USA


G. R. Aiken

U.S. Geological Survey, Boulder, Colorado, USA


T. Y. Gurtovaya

South Russian Regional Centre for Preparation and Implementation of International Projects, Rostov-on-Don, Russia


Abstract

The export and Δ14C-age of dissolved organic carbon (DOC) was determined for the Yenisey, Lena, Ob', Mackenzie, and Yukon rivers for 2004–2005. Concentrations of DOC elevate significantly with increasing discharge in these rivers, causing approximately 60% of the annual export to occur during a 2-month period following spring ice breakup. We present a total annual flux from the five rivers of ∼16 teragrams (Tg), and conservatively estimate that the total input of DOC to the Arctic Ocean is 25–36 Tg, which is ∼5–20% greater than previous fluxes. These fluxes are also ∼2.5× greater than temperate rivers with similar watershed sizes and water discharge. Δ14C-DOC shows a clear relationship with hydrology. A small pool of DOC slightly depleted in Δ14C is exported with base flow. The large pool exported with spring thaw is enriched in Δ14C with respect to current-day atmospheric Δ14C-CO2 values. A simple model predicts that ∼50% of DOC exported during the arctic spring thaw is 1–5 years old, ∼25% is 6–10 years in age, and 15% is 11–20 years old. The dominant spring melt period, a historically undersampled period, exports a large amount of young and presumably semilabile DOC to the Arctic Ocean.

Received 17 January 2007; accepted 6 July 2007; published 2 November 2007.

Keywords: DOC; Arctic; river.

Index Terms: 0414 Biogeosciences: Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912); 0428 Biogeosciences: Carbon cycling (4806); 0454 Biogeosciences: Isotopic composition and chemistry (1041, 4870); 1030 Geochemistry: Geochemical cycles (0330).

Read Full Article (file size: 487044 bytes)    Cited by

Citation: Raymond, P. A., J. W. McClelland, R. M. Holmes, A. V. Zhulidov, K. Mull, B. J. Peterson, R. G. Striegl, G. R. Aiken, and T. Y. Gurtovaya (2007), Flux and age of dissolved organic carbon exported to the Arctic Ocean: A carbon isotopic study of the five largest arctic rivers, Global Biogeochem. Cycles, 21, GB4011, doi:10.1029/2007GB002934.