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Changes in 14C Activity Over Time During Vacuum Distillation of Carbon from Rock Pore Water

Published online by Cambridge University Press:  18 July 2016

G R Davidson
Affiliation:
Department of Geology and Geological Engineering, Carrier Hall, The University of Mississippi University MS 38677 USA
I C Yang
Affiliation:
US Geological Survey, MS-421, Lakewood, CO 80225 USA
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Abstract

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The radiocarbon activity of carbon collected by vacuum distillation from a single partially saturated tuff began to decline after approximately 60% of the water and carbon had been extracted. Disproportionate changes in 14C activity and δ13C during distillation rule out simple isotopic fractionation as a causative explanation. Additional phenomena such as matrix diffusion and ion exclusion in micropores may play a role in altering the isotopic value of extracted carbon, but neither can fully account for the observed changes. The most plausible explanation is that distillation recovers carbon from an adsorbed phase that is depleted in 14C relative to DIC in the bulk pore water.

Type
Articles
Copyright
Copyright © The American Journal of Science 

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