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A New Method for Analyzing 14C of Methane in Ancient Air Extracted from Glacial Ice

  • Vasilii V Petrenko (a1), Andrew M Smith (a2), Gordon Brailsford (a3), Katja Riedel (a3), Quan Hua (a2), Dave Lowe (a3), Jeffrey P Severinghaus (a1), Vladimir Levchenko (a2), Tony Bromley (a3), Rowena Moss (a3), Jens Mühle (a1) and Edward J Brook (a4)...

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.

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Brasseur, GP, Orlando, JJ, Tyndall, GS, editors. 1999. Atmospheric Chemistry and Global Change. New York: Oxford University Press. 654 p.
Brenninkmeijer, CAM. 1991. Robust, high-efficiency, high-capacity cryogenic trap. Analytical Chemistry 63(11):1182–4.
Brenninkmeijer, CAM. 1993. Measurement of the abundance of 14CO in the atmosphere and the 13C/12C and 18O/16O ratio of atmospheric CO with applications in New Zealand and Antarctica. Journal of Geophysical Research 98(D6):10,595614.
Brenninkmeijer, CAM, Röckmann, T. 1996. Russian doll type cryogenic traps: improved design and isotope separation effects. Analytical Chemistry 68(17):3050–3.
Brook, EJ, Harder, S, Severinghaus, J, Steig, EJ, Sucher, CM. 2000. On the origin and timing of rapid changes in atmospheric methane during the last glacial period. Global Biogeochemical Cycles 14(2):559–72.
Buffett, B, Archer, D. 2004. Global inventory of methane clathrate: sensitivity to changes in the deep ocean. Earth and Planetary Science Letters 227(3–4):185–99.
Chappellaz, J, Bluniert, T, Raynaud, D, Barnola, JM, Schwander, J, Stauffer, B. 1993. Synchronous changes in atmospheric CH4 and Greenland climate between 40 and 8 kyr BR Nature 366(6454):443–5.
Colussi, AJ, Hoffmann, MR. 2003. In situ photolysis of deep ice core contaminants by Cerenkov radiation of cosmic origin. Geophysical Research Letters 30(4):1195, doi:10.1029/2002GL016112.
Conny, JM, Currie, LA. 1996. The isotopic characterization of methane, non-methane hydrocarbons and formaldehyde in the troposphere. Atmospheric Environment 30(4):621–38.
Etheridge, DM, Steele, LP, Francey, RJ, Langenfelds, RL. 1998. Atmospheric methane between 1000 AD and present: evidence of anthropogenic emissions and climatic variability. Journal of Geophysical Research 103(D13):15,97993.
Ferretti, DF, Miller, JB, White, JWC, Etheridge, DM, Lassey, KR, Lowe, DC, MacFarling Meure, CM, Dreier, MF, Trudinger, CM, van Ommen, TD, Langenfelds, RL. 2005a. Unexpected changes to the global methane budget over the past 2000 years. Science 309(5741):1714–7.
Ferretti, D, Fraser, A, Lassey, K, Martin, R, Brailsford, G, McGregor, J. 2005b. Using electrical sensors to estimate methane emissions from farm animals. Paper presented at the Meteorological Society of New Zealand Annual Conference. Wellington, New Zealand.
Fink, D, Hotchkis, M, Hua, Q, Jacobsen, G, Smith, AM, Zoppi, U, Child, D, Mifsud, C, van der Gaast, H, Williams, A, Williams, M. 2004. The ANTARES AMS facility at ANSTO. Nuclear Instruments and Methods in Physics Research B 223–224:109–15.
Fisher, R, Lowry, D, Wilkin, O, Sriskantharajah, S, Nisbet, EG. 2006. High-precision, automated stable isotope analysis of atmospheric methane and carbon dioxide using continuous-flow isotope-ratio mass spectrometry. Rapid Communications in Mass Spectrometry 20(2):200–8.
Forster, P, Ramaswamy, V, Artaxo, P, Berntsen, T, Betts, R, Fahey, DW, Haywood, J, Lean, J, Lowe, DC, Myhre, G, Nganga, J, Prinn, R, Raga, G, Schulz, M, Van Dorland, R. 2007. Changes in atmospheric constituents and in radiative forcing. In: Solomon, S, Qin, D, Manning, M, Chen, Z, Marquis, M, Averyt, KB, Tignor, M, Miller, HL, editors. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press. p 130234.
Foulger, BE, Simmonds, PG. 1993. Ambient temperature gas purifier suitable for the trace analysis of carbon monoxide and hydrogen and the preparation of low-level carbon monoxide calibration standards in the field. Journal of Chromatography 630(1–2):257–63.
Grabowski, KS, Knies, DL, Tumey, SJ, Pohlman, JW, Mitchell, CS, Coffin, RB. 2004. Carbon pool analysis of methane hydrate regions in the seafloor by accelerator mass spectrometry. Nuclear Instruments and Methods in Physics Research B 223–224:435–40.
Haan, D, Raynaud, D. 1998. Ice core record of CO variations during the last two millennia: atmospheric implications and chemical interactions within the Greenland ice. Tellus B 50(3):253–62.
Hua, Q, Jacobsen, GE, Zoppi, U, Lawson, EM, Williams, AA, Smith, AM, McGann, MJ. 2001. Progress in radiocarbon target preparation at the ANTARES AMS Centre. Radiocarbon 43(2A):275–82.
Hua, Q, Zoppi, U, Williams, AA, Smith, AM. 2004. Small-mass AMS radiocarbon analysis at ANTARES. Nuclear Instruments and Methods in Physics Research B 223–224:284–92.
Kennett, JP, Cannariato, KG, Hendy, IL, Behl, RJ. 2000. Carbon isotopic evidence for methane hydrate instability during Quaternary interstadials. Science 288(5463):128–33.
Kennett, JP, Cannariato, KG, Hendy, IL, Behl, RJ. 2003. Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis. Washington, DC: American Geophysical Union. 216 p.
Kessler, JD, Reeburgh, WS. 2005. Preparation of natural methane samples for stable isotope and radiocarbon analysis. Limnology and Oceanography-Methods 3:408–18.
Kessler, JD, Reeburgh, WS, Southon, J, Seifert, R, Michaelis, W, Tyler, SC. 2006. Basin-wide estimates of the input of methane from seeps and clathrates to the Black Sea. Earth and Planetary Science Letters 243(3–4):366–75.
Lal, D, Jull, AJT, Burr, GS, Donahue, DJ. 2000. On the characteristics of cosmogenic in situ 14C in some GISP2 Holocene and late glacial ice samples. Nuclear Instruments and Methods in Physics Research B 172(1–4):623–31.
Lassey, KR, Lowe, DC, Smith, AM. 2007. The atmospheric cycling of radiomethane and the “fossil fraction” of the methane source. Atmospheric Chemistry and Physics 7(8):2141–9.
Lowe, DC, Brenninkmeijer, CAM, Tyler, SC, Dlugkencky, EJ. 1991. Determination of the isotopic composition of atmospheric methane and its application in the Antarctic. Journal of Geophysical Research 96(D8):15,45567.
Milkov, AV. 2004. Global estimates of hydrate-bound gas in marine sediments: how much is really out there? Earth-Science Reviews 66(3–4):183–97.
Mühle, J, Lueker, TJ, Su, Y, Miller, BR, Prather, KA, Weiss, RF. 2007. Trace gas and particulate emissions from the 2003 southern California wildfires. Journal of Geophysical Research 112(D3): D03307, doi:10.1029/2006JD007350.
Petrenko, VV, Severinghaus, JP, Brook, EJ, Reeh, N, Schaefer, H. 2006. Gas records from the West Greenland ice margin covering the Last Glacial Termination: a horizontal ice core. Quaternary Science Reviews 25(9–10):865–75.
Petrenko, VV, Severinghaus, JP, Brook, EJ, Mühle, J, Headly, M, Harth, C, Schaefer, H, Reeh, N, Weiss, RF, Lowe, D, Smith, AM. 2008. Instruments and Methods: A novel method for obtaining very large ancient air samples from ablating glacial ice for analyses of methane radiocarbon. Journal of Glaciology 54(185), in press.
Price, PB. 2007. Microbial life in glacial ice and implications for a cold origin of life. FEMS Microbiology Ecology 59(2):217–31.
Pupek, M, Assonov, SS, Mühle, J, Rhee, TS, Oram, D, Koeppel, C, Slemr, F, Brenninkmeijer, CAM. 2005. Isotope analysis of hydrocarbons: trapping, recovering and archiving hydrocarbons and halocarbons separated from ambient air. Rapid Communications in Mass Spectrometry 19(4):455–60.
Quay, P, Stutsman, J, Wilbur, D, Snover, A, Dlugokencky, E, Brown, T. 1999. The isotopic composition of atmospheric methane. Global Biogeochemical Cycles 13(2):445–61.
Reeh, N, Oerter, H, Letréguilly, A, Miller, H, Hubberten, H-W. 1991. A new, detailed Ice-Age oxygen-18 record from the ice-sheet margin in central West Greenland. Global and Planetary Change 4(4):373–83.
Schaefer, H, Whiticar, MJ, Brook, EJ, Petrenko, VV, Ferretti, DF, Severinghaus, JP. 2006. Ice record of δ13C for atmospheric CH4 across the Younger Dryas-Preboreal transition. Science 313(5790):1109–12.
Smith, AM, Levchenko, VA, Etheridge, DM, Lowe, DC, Hua, Q, Trudinger, CM, Zoppi, U, Elcheikh, A. 2000. In search of in-situ radiocarbon in Law Dome ice and firn. Nuclear Instruments and Methods in Physics Research B 172(1–4):610–22.
Smith, AM, Petrenko, VV, Hua, Q, Southon, J, Brailsford, G. 2007. The effect of N2O, catalyst, and means of water vapor removal on the graphitization of small CO2 samples. Radiocarbon 49(2):245–54.
Sowers, T. 2006. Late Quaternary atmospheric CH4 isotope record suggests marine clathrates are stable. Science 311(5762):838–40.
Stuiver, M. 1983. International agreements and the use of the new oxalic acid standard. Radiocarbon 25(2):793–5.
Stuiver, M, Polach, HA. 1977. Discussion: reporting of 14C data. Radiocarbon 19(3):355–63.
Van de Wal, RSW, Meijer, HAJ, de Rooij, M, van der Veen, C. 2007. Radiocarbon analyses along the EDML ice core in Antarctica. Tellus B 59(1):157–65.
Wahlen, M, Tanaka, N, Henry, R, Deck, B, Zeglen, J, Vogel, JS, Southon, J, Shemesh, A, Fairbanks, R, Broecker, W. 1989. Carbon-14 in methane sources and in atmospheric methane: the contribution from fossil carbon. Science 245(4915):286–90.
Winckler, G, Aeschbach-Hertig, W, Holocher, J, Kipfer, R, Levin, I, Poss, C, Rehder, G, Suess, E, Schlosser, P. 2002. Noble gases and radiocarbon in natural gas hydrates. Geophysical Research Letters 29(10): doi:10.1029/2001GL014013.
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