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Carbon isotope constraints on vertical mixing and air‐sea CO 2 exchange
Author(s) -
Fallon Stewart J.,
Guilderson Thomas P.,
Caldeira Ken
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018049
Subject(s) - tracer , diffusion , isotopes of carbon , environmental science , thermal diffusivity , radiocarbon dating , microscale chemistry , isotope , oceanography , atmospheric sciences , carbon fibers , geology , climatology , materials science , physics , nuclear physics , thermodynamics , paleontology , mathematics education , mathematics , composite number , composite material
We have developed a ∼45 year carbon isotope record (δ 13 C, Δ 14 C) from the coralline sponge Acanthochaetetes wellsi from Vanuatu in an effort to examine air‐sea CO 2 exchange using both the δ 13 C Suess effect and the bomb‐ 14 C transient. From 1953 to 1999 δ 13 C decreased by 0.9‰. Pre‐bomb Δ 14 C is ‐59‰, consistent with coral based estimates from the same region and the post‐bomb maximum (+121‰) is achieved in 1973. A 1‐D box‐diffusion model was employed to quantify vertical diffusivity and air‐sea exchange rates. The model suggests that a low vertical diffusion rate (0.1 cm 2 s ‐1 ) coupled with a moderate CO 2 exchange rate produces the overall observed shape of the pre‐post bomb Δ 14 C record and the general large scale features of the δ 13 C time series. These parameters are on the low end of values used in ocean‐carbon GCMs but are consistent with microscale tracer experiments.