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Flux and age of dissolved organic carbon exported to the Arctic Ocean: A carbon isotopic study of the five largest arctic rivers
Author(s) -
Raymond Peter A.,
McClelland J. W.,
Holmes R. M.,
Zhulidov A. V.,
Mull K.,
Peterson B. J.,
Striegl R. G.,
Aiken G. R.,
Gurtovaya T. Y.
Publication year - 2007
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2007gb002934
Subject(s) - dissolved organic carbon , arctic , environmental science , spring (device) , total organic carbon , flux (metallurgy) , oceanography , hydrology (agriculture) , temperate climate , period (music) , geology , environmental chemistry , ecology , chemistry , organic chemistry , biology , mechanical engineering , physics , geotechnical engineering , acoustics , engineering
The export and Δ 14 C‐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. Δ 14 C‐DOC shows a clear relationship with hydrology. A small pool of DOC slightly depleted in Δ 14 C is exported with base flow. The large pool exported with spring thaw is enriched in Δ 14 C with respect to current‐day atmospheric Δ 14 C‐CO 2 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.