Record Details
A New Method for Analyzing ¹⁴C of Methane in Ancient Air Extracted from Glacial Ice
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | A New Method for Analyzing ¹⁴C of Methane in Ancient Air Extracted from Glacial Ice |
| Names |
Petrenko, Vasilii V.
(creator) Smith, Andrew M. (creator) Brailsford, Gordon (creator) Riedel, Katja (creator) Hua, Quan (creator) Lowe, Dave (creator) Severinghaus, Jeffrey P. (creator) Levchenko, Vladimir (creator) Bromley, Tony (creator) Moss, Rowena (creator) Muhle, Jens (creator) Brook, Edward J. (creator) |
| Date Issued | 2008 (iso8601) |
| Note | This is the publisher’s final pdf. The published article is copyrighted by the University of Arizona and can be found at: https://journals.uair.arizona.edu/index.php/radiocarbon/index. |
| Abstract | We present a new method developed for measuring radiocarbon of methane (¹⁴CH₄) in ancient air samples extracted from glacial ice and dating 11,000–15,000 calendar years before present. The small size (~20 μg CH₄ carbon), low CH₄ concentrations ([CH₄], 400–800 parts per billion [ppb]), high carbon monoxide concentrations ([CO]), and low ¹⁴C activity of the samples created unusually high risks of contamination by extraneous carbon. Up to 2500 ppb CO in the air samples was quantitatively removed using the Sofnocat reagent. ¹⁴C procedural blanks were greatly reduced through the construction of a new CH₄ conversion line utilizing platinized quartz wool for CH₄ combustion and the use of an ultra-high-purity iron catalyst for graphitization. The amount and ¹⁴C activity of extraneous carbon added in the new CH₄ conversion line were determined to be 0.23 ± 0.16 μg and 23.57 ± 16.22 pMC, respectively. The amount of modern (100 pMC) carbon added during the graphitization step has been reduced to 0.03 μg. The overall procedural blank for all stages of sample handling was 0.75 ± 0.38 pMC for ~20-μg, ¹⁴C-free air samples with [CH₄] of 500 ppb. Duration of the graphitization reactions for small (<25 μg C) samples was greatly reduced and reaction yields improved through more efficient water vapor trapping and the use of a new iron catalyst with higher surface area. ¹⁴C corrections for each step of sample handling have been determined. The resulting overall ¹⁴CH₄ uncertainties for the ancient air samples are ~1.0 pMC. |
| Genre | Article |
| Identifier | Petrenko, V. V., Smith, A. M., Brailsford, G., Riedel, K., Hua, Q., Lowe, D., & Brook, E. J. A new method for analyzing ¹⁴C of methane in ancient air extracted from glacial ice [Electronic version]. Radiocarbon, 50(1), 53-79. |
