Document Type

Article

Publication Title

Journal of Glaciology

Rights and Access Note

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Publication Date

2008

First Page

685

Last Page

695

Issue Number

187

Volume Number

54

Abstract/ Summary

One common assumption in interpreting ice-core CO(2) records is that diffusion in the ice does not affect the concentration profile. However, this assumption remains untested because the extremely small CO(2) diffusion coefficient in ice has not been accurately determined in the laboratory. In this study we take advantage of high levels of CO(2) associated with refrozen layers in an ice core from Siple Dome, Antarctica, to study CO(2) diffusion rates. We use noble gases (Xe/Ar and Kr/Ar), electrical conductivity and Ca(2+) ion concentrations to show that substantial CO(2) diffusion may occur in ice on timescales of thousands of years. We estimate the permeation coefficient for CO(2) in ice is similar to 4 x 10(-21) mol m(-1) s(-1) Pa(-1) at -23 degrees C in the top 287 m (corresponding to 2.74 kyr). Smoothing of the CO(2) record by diffusion at this depth/age is one or two orders of magnitude smaller than the smoothing in the firn. However, simulations for depths of similar to 930-950m (similar to 60-70 kyr) indicate that smoothing of the CO(2) record by diffusion in deep ice is comparable to smoothing in the firn. Other types of diffusion (e.g. via liquid in ice grain boundaries or veins) may also be important but their influence has not been quantified.

Citation/Publisher Attribution

Ahn, J, Headly, M, Wahlen, M, Brook, EJ, Mayewski, PA, and Taylor, KC, 2008, CO(2) Diffusion in Polar Ice: Observations from Naturally Formed CO(2) Spikes in the Siple Dome (Antarctica) Ice Core: Journal of Glaciology, v. 54, p. 685-695. Available on publisher's site at: http://www.ingentaconnect.com/content/igsoc/jog/2008/00000054/00000187/art00012

Publisher Statement

© Copyright 2008 by the International Glaciological Society

DOI

10.3189/002214308786570764

Version

publisher's version of the published document

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In Copyright - Educational Use Permitted.