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标题：CO2 diffusion in polar ice: observations from naturally formed CO2 spikes in the Siple Dome (Antarctica) ice core
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作者：Jinho Ahn ; Melissa Headly ; Martin Wahlen 等
期刊名称：Journal of Glaciology
印刷版ISSN：0022-1430
电子版ISSN：1727-5652
出版年度：2008
卷号：54
期号：187
页码：685-695
DOI：10.3189/002214308786570764
出版社：Cambridge University Press
摘要：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 ∼ 4 × 10 −21 mol m −1 s −1 Pa −1 at −23°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 ∼930–950 m (∼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.