Articles | Volume 13, issue 14
Atmos. Chem. Phys., 13, 6993–7005, 2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Special issue: Firn air: archive of the recent atmosphere
Research article 24 Jul 2013
Research article | 24 Jul 2013
Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements?
C. J. Sapart et al.
Related subject area
Subject: Isotopes | Research Activity: Field Measurements | Altitude Range: Troposphere | Science Focus: Chemistry (chemical composition and reactions)Baffin Bay sea ice extent and synoptic moisture transport drive water vapor isotope (δ18O, δ2H, and deuterium excess) variability in coastal northwest GreenlandNew evidence for atmospheric mercury transformations in the marine boundary layer from stable mercury isotopesThe isotopic composition of atmospheric nitrous oxide observed at the high-altitude research station Jungfraujoch, SwitzerlandDeposition, recycling, and archival of nitrate stable isotopes between the air–snow interface: comparison between Dronning Maud Land and Dome C, AntarcticaOxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ33S reservoir of sulfate aerosols?Atmospheric radiocarbon measurements to quantify CO2 emissions in the UK from 2014 to 2015An improved estimate for the δ13C and δ18O signatures of carbon monoxide produced from atmospheric oxidation of volatile organic compoundsSeasonality in the Δ33S measured in urban aerosols highlights an additional oxidation pathway for atmospheric SO2The Δ17O and δ18O values of atmospheric nitrates simultaneously collected downwind of anthropogenic sources – implications for polluted air massesA very limited role of tropospheric chlorine as a sink of the greenhouse gas methaneDetection and variability of combustion-derived vapor in an urban basinStable sulfur isotope measurements to trace the fate of SO2 in the Athabasca oil sands regionTriple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric depositionIsotopic constraints on heterogeneous sulfate production in Beijing hazeEstimation of the fossil fuel component in atmospheric CO2 based on radiocarbon measurements at the Beromünster tall tower, SwitzerlandConstraining N2O emissions since 1940 using firn air isotope measurements in both hemispheresSeasonal variations of triple oxygen isotopic compositions of atmospheric sulfate, nitrate, and ozone at Dumont d'Urville, coastal AntarcticaCarbon isotopic signature of coal-derived methane emissions to the atmosphere: from coalification to alterationIsotopic composition for source identification of mercury in atmospheric fine particlesIsotopic constraints on the role of hypohalous acids in sulfate aerosol formation in the remote marine boundary layerIn situ observations of the isotopic composition of methane at the Cabauw tall tower siteOxygen isotope mass balance of atmospheric nitrate at Dome C, East Antarctica, during the OPALE campaignIsotopic effects of nitrate photochemistry in snow: a field study at Dome C, AntarcticaStable carbon isotope ratios of ambient secondary organic aerosols in TorontoWAIS Divide ice core suggests sustained changes in the atmospheric formation pathways of sulfate and nitrate since the 19th century in the extratropical Southern HemisphereStable carbon isotope ratios of toluene in the boundary layer and the lower free troposphereEmission ratio and isotopic signatures of molecular hydrogen emissions from tropical biomass burningAir–snow transfer of nitrate on the East Antarctic Plateau – Part 1: Isotopic evidence for a photolytically driven dynamic equilibrium in summerChemical characterization and stable carbon isotopic composition of particulate Polycyclic Aromatic Hydrocarbons issued from combustion of 10 Mediterranean woodsQuantification of the carbonaceous matter origin in submicron marine aerosol by 13C and 14C isotope analysisTemporal and spatial variability of the stable isotopic composition of atmospheric molecular hydrogen: observations at six EUROHYDROS stationsContinuous isotopic composition measurements of tropospheric CO2 at Jungfraujoch (3580 m a.s.l.), Switzerland: real-time observation of regional pollution eventsAnthropogenic imprints on nitrogen and oxygen isotopic composition of precipitation nitrate in a nitrogen-polluted city in southern ChinaAnalysis of 13C and 18O isotope data of CO2 in CARIBIC aircraft samples as tracers of upper troposphere/lower stratosphere mixing and the global carbon cycleTracing the fate of atmospheric nitrate deposited onto a forest ecosystem in Eastern Asia using Δ17OPhotolysis imprint in the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cyclingSources and transport of Δ14C in CO2 within the Mexico City Basin and vicinity
Pete D. Akers, Ben G. Kopec, Kyle S. Mattingly, Eric S. Klein, Douglas Causey, and Jeffrey M. Welker
Atmos. Chem. Phys., 20, 13929–13955,Short summary
Water vapor isotopes recorded for 2 years in coastal northern Greenland largely reflect changes in sea ice cover, with distinct values when Baffin Bay is ice covered in winter vs. open in summer. Resulting changes in moisture transport, surface winds, and air temperature also modify the isotopes. Local glacial ice may thus preserve past changes in the Baffin Bay sea ice extent, and this will help us better understand how the Arctic environment and water cycle responds to global climate change.
Ben Yu, Lin Yang, Linlin Wang, Hongwei Liu, Cailing Xiao, Yong Liang, Qian Liu, Yongguang Yin, Ligang Hu, Jianbo Shi, and Guibin Jiang
Atmos. Chem. Phys., 20, 9713–9723,Short summary
We found that Br atoms in the marine boundary layer are the most probable oxidizer that transform gaseous elemental mercury into gaseous oxidized mercury, according to the mercury isotopes in the total gaseous mercury. On the other hand, Br or Cl atoms are not the primary oxidizers that produced oxidized mercury on particles. This study showed that mercury isotopes can provide new evidence that help us to fully understand the transformations of atmospheric mercury.
Longfei Yu, Eliza Harris, Stephan Henne, Sarah Eggleston, Martin Steinbacher, Lukas Emmenegger, Christoph Zellweger, and Joachim Mohn
Atmos. Chem. Phys., 20, 6495–6519,Short summary
We observed the isotopic composition of nitrous oxide in the unpolluted air at Jungfraujoch for 5 years. Our results indicate a clear seasonal pattern in the isotopic composition, corresponding with that in atmospheric nitrous oxide levels. This is most likely due to temporal variations in both emission processes and air mass sources for Jungfraujoch. Our findings are of importance to global nitrous oxide modelling and to better understanding of long-term trends in atmospheric nitrous oxide.
V. Holly L. Winton, Alison Ming, Nicolas Caillon, Lisa Hauge, Anna E. Jones, Joel Savarino, Xin Yang, and Markus M. Frey
Atmos. Chem. Phys., 20, 5861–5885,Short summary
The transfer of the nitrogen stable isotopic composition in nitrate between the air and snow at low accumulation sites in Antarctica leaves an UV imprint in the snow. Quantifying how nitrate isotope values change allows us to interpret longer ice core records. Based on nitrate observations and modelling at Kohnen, East Antarctica, the dominant factors controlling the nitrate isotope signature in deep snow layers are the depth of light penetration into the snowpack and the snow accumulation rate.
Isabelle Genot, David Au Yang, Erwan Martin, Pierre Cartigny, Erwann Legendre, and Marc De Rafelis
Atmos. Chem. Phys., 20, 4255–4273,Short summary
Given their critical impact on radiative forcing, sulfate aerosols have been extensively studied using their isotope signatures (δ34S, ∆33S, ∆36S, δ18O, and ∆17O). A striking observation is that ∆33S > 0 ‰, implying a missing reservoir in the sulfur cycle. Here, we measured ∆33S < 0 ‰ in black crust sulfates (i.e., formed on carbonate walls) that must therefore result from distinct chemical pathway(s) compared to sulfate aerosols, and they may well represent this complementary reservoir.
Angelina Wenger, Katherine Pugsley, Simon O'Doherty, Matt Rigby, Alistair J. Manning, Mark F. Lunt, and Emily D. White
Atmos. Chem. Phys., 19, 14057–14070,Short summary
We present 14CO2 observations at a background site in Ireland and a tall tower site in the UK. These data have been used to calculate the contribution of fossil fuel sources to atmospheric CO2 mole fractions from the UK and Ireland. 14CO2 emissions from nuclear industry sites in the UK cause a higher uncertainty in the results compared to observations in other locations. The observed ffCO2 at the site was not significantly different from simulated values based on the bottom-up inventory.
Isaac J. Vimont, Jocelyn C. Turnbull, Vasilii V. Petrenko, Philip F. Place, Colm Sweeney, Natasha Miles, Scott Richardson, Bruce H. Vaughn, and James W. C. White
Atmos. Chem. Phys., 19, 8547–8562,Short summary
Stable isotopes of Carbon Monoxide (CO) and radiocarbon carbon dioxide were measured over three summers at Indianapolis, Indiana, US, and for 1 year at a site thought to be strongly influenced by CO from oxidized volatile organic compounds (VOCs) in South Carolina, US. The Indianapolis results were used to provide an estimate of the carbon and oxygen isotopic signatures of CO produced from oxidized VOCs. This updated estimate agrees well with the data from South Carolina during the summer.
David Au Yang, Pierre Cartigny, Karine Desboeufs, and David Widory
Atmos. Chem. Phys., 19, 3779–3796,Short summary
Sulfates present in urban aerosols collected worldwide usually exhibit 33S-anomalies whose origin remains unclear. Besides, the sulfate concentration is not very well modelled nowadays, which, coupled with the isotopic composition anomaly on the 33S, would highlight the presence of at least an additional oxidation pathway, different from O2+TMI, O3, OH, H2O2 and NO2. We suggest here the implication of two other possible oxidation pathways.
Martine M. Savard, Amanda S. Cole, Robert Vet, and Anna Smirnoff
Atmos. Chem. Phys., 18, 10373–10389,Short summary
Improving air quality requires understanding of the atmospheric processes transforming nitrous oxides emitted by human activities into nitrates, an N form that may degrade natural ecosystems. Isotopes (∆17O, δ18O) are characterized in separate wet, particulate and gaseous nitrates for the first time. The gas ranges are distinct from those of the other nitrates, and the plume dynamics emerge as crucial in interpreting the results, which unravel key processes behind the distribution of nitrates.
Sergey Gromov, Carl A. M. Brenninkmeijer, and Patrick Jöckel
Atmos. Chem. Phys., 18, 9831–9843,Short summary
Using the observational data on 13C (CO) and 13C (CH4) from the extra-tropical Southern Hemisphere (ETSH) and EMAC model we (1) provide an independent, observation-based evaluation of Cl atom concentration variations in the ETSH throughout 1994–2000, (2) show that the role of tropospheric Cl as a sink of CH4 is seriously overestimated in the literature, (3) demonstrate that the 13C/12C ratio of CO is a sensitive indicator for the isotopic composition of reacted CH4 and therefore for its sources.
Richard P. Fiorella, Ryan Bares, John C. Lin, James R. Ehleringer, and Gabriel J. Bowen
Atmos. Chem. Phys., 18, 8529–8547,Short summary
Fossil fuel combustion produces water; where fossil fuel combustion is concentrated in urban areas, this humidity source may represent ~ 10 % of total humidity. In turn, this water vapor addition may alter urban meteorology, though the contribution of combustion vapor is difficult to measure. Using stable water isotopes, we estimate that up to 16 % of urban humidity may arise from combustion when the atmosphere is stable during winter, and develop recommendations for application in other cities.
Neda Amiri, Roghayeh Ghahremaninezhad, Ofelia Rempillo, Travis W. Tokarek, Charles A. Odame-Ankrah, Hans D. Osthoff, and Ann-Lise Norman
Atmos. Chem. Phys., 18, 7757–7780,
David M. Nelson, Urumu Tsunogai, Dong Ding, Takuya Ohyama, Daisuke D. Komatsu, Fumiko Nakagawa, Izumi Noguchi, and Takashi Yamaguchi
Atmos. Chem. Phys., 18, 6381–6392,Short summary
Atmospheric nitrate may be produced locally and/or come from upwind regions. To address this issue we measured oxygen and nitrogen isotopes of wet and dry nitrate deposition at nearby urban and rural sites. Our results suggest that, relative to nitrate in wet deposition in urban environments and wet and dry deposition in rural environments, nitrate in dry deposition in urban environments results from local NOx emissions more so than wet deposition, which is transported longer distances.
Pengzhen He, Becky Alexander, Lei Geng, Xiyuan Chi, Shidong Fan, Haicong Zhan, Hui Kang, Guangjie Zheng, Yafang Cheng, Hang Su, Cheng Liu, and Zhouqing Xie
Atmos. Chem. Phys., 18, 5515–5528,Short summary
We use observations of the oxygen isotopic composition of sulfate aerosol as a fingerprint to quantify various sulfate formation mechanisms during pollution events in Beijing, China. We found that heterogeneous reactions on aerosols dominated sulfate production in general; however, in-cloud reactions would dominate haze sulfate production when cloud liquid water content was high. The findings also suggest the heterogeneity of aerosol acidity should be parameterized in models.
Tesfaye A. Berhanu, Sönke Szidat, Dominik Brunner, Ece Satar, Rüdiger Schanda, Peter Nyfeler, Michael Battaglia, Martin Steinbacher, Samuel Hammer, and Markus Leuenberger
Atmos. Chem. Phys., 17, 10753–10766,Short summary
Fossil fuel CO2 is the major contributor of anthropogenic CO2 in the atmosphere, and accurate quantification is essential to better understand the carbon cycle. Such accurate quantification can be conducted based on radiocarbon measurements. In this study, we present radiocarbon measurements from a tall tower site in Switzerland. From these measurements, we have observed seasonally varying fossil fuel CO2 contributions and a biospheric CO2 component that varies diurnally and seasonally.
Markella Prokopiou, Patricia Martinerie, Célia J. Sapart, Emmanuel Witrant, Guillaume Monteil, Kentaro Ishijima, Sophie Bernard, Jan Kaiser, Ingeborg Levin, Thomas Blunier, David Etheridge, Ed Dlugokencky, Roderik S. W. van de Wal, and Thomas Röckmann
Atmos. Chem. Phys., 17, 4539–4564,Short summary
Nitrous oxide is the third most important anthropogenic greenhouse gas with an increasing mole fraction. To understand its natural and anthropogenic sources we employ isotope measurements. Results show that while the N2O mole fraction increases, its heavy isotope content decreases. The isotopic changes observed underline the dominance of agricultural emissions especially at the early part of the record, whereas in the later decades the contribution from other anthropogenic sources increases.
Sakiko Ishino, Shohei Hattori, Joel Savarino, Bruno Jourdain, Susanne Preunkert, Michel Legrand, Nicolas Caillon, Albane Barbero, Kota Kuribayashi, and Naohiro Yoshida
Atmos. Chem. Phys., 17, 3713–3727,Short summary
We show the first simultaneous observations of triple oxygen isotopic compositions of atmospheric sulfate, nitrate, and ozone at Dumont d'Urville, coastal Antarctica. The contrasting seasonal trends between oxygen isotopes of ozone and those of sulfate and nitrate indicate that these signatures in sulfate and nitrate are mainly controlled by changes in oxidation chemistry. We also discuss the specific oxidation chemistry induced by the unique phenomena at the site.
Giulia Zazzeri, Dave Lowry, Rebecca E. Fisher, James L. France, Mathias Lanoisellé, Bryce F. J. Kelly, Jaroslaw M. Necki, Charlotte P. Iverach, Elisa Ginty, Miroslaw Zimnoch, Alina Jasek, and Euan G. Nisbet
Atmos. Chem. Phys., 16, 13669–13680,Short summary
Methane emissions estimates from the coal sector are highly uncertain. Precise δ13C isotopic signatures of methane sources can be used in atmospheric models for a methane budget assessment. Emissions from both underground and opencast coal mines in the UK, Australia and Poland were sampled and isotopically characterised using high-precision measurements of δ13C values. Representative isotopic signatures were provided, taking into account specific ranks of coal and mine type.
Qiang Huang, Jiubin Chen, Weilin Huang, Pingqing Fu, Benjamin Guinot, Xinbin Feng, Lihai Shang, Zhuhong Wang, Zhongwei Wang, Shengliu Yuan, Hongming Cai, Lianfang Wei, and Ben Yu
Atmos. Chem. Phys., 16, 11773–11786,Short summary
Atmospheric airborne mercury is of particular concern because, once inhaled, both Hg and its vectors might have adverse effects on human beings. In this study, we attempted to identify the sources of PM2.5-Hg in Beijing, China, using Hg isotopic composition. Large range and seasonal variations in both mass-dependent and mass-independent fractionations of Hg isotopes in haze particles demonstrate the usefulness of Hg isotopes for directly tracing the sources and its vectors in the atmosphere.
Qianjie Chen, Lei Geng, Johan A. Schmidt, Zhouqing Xie, Hui Kang, Jordi Dachs, Jihong Cole-Dai, Andrew J. Schauer, Madeline G. Camp, and Becky Alexander
Atmos. Chem. Phys., 16, 11433–11450,Short summary
The formation mechanisms of sulfate in the marine boundary layer are not well understood, which could result in large uncertainties in aerosol radiative forcing. We measure the oxygen isotopic composition (Δ17O) of sulfate collected in the MBL and analyze with a global transport model. Our results suggest that 33–50 % of MBL sulfate is formed via oxidation of S(IV) by hypohalous acids HOBr / HOCl in the aqueous phase, and the daily-mean HOBr/HOCl concentrations are on the order of 0.01–0.1 ppt.
Thomas Röckmann, Simon Eyer, Carina van der Veen, Maria E. Popa, Béla Tuzson, Guillaume Monteil, Sander Houweling, Eliza Harris, Dominik Brunner, Hubertus Fischer, Giulia Zazzeri, David Lowry, Euan G. Nisbet, Willi A. Brand, Jaroslav M. Necki, Lukas Emmenegger, and Joachim Mohn
Atmos. Chem. Phys., 16, 10469–10487,Short summary
A dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS)-based technique were deployed at the Cabauw experimental site for atmospheric research (CESAR) in the Netherlands and performed in situ, high-frequency (approx. hourly) measurements for a period of more than 5 months, yielding a combined dataset with more than 2500 measurements of both δ13C and δD.
Joël Savarino, William C. Vicars, Michel Legrand, Suzanne Preunkert, Bruno Jourdain, Markus M. Frey, Alexandre Kukui, Nicolas Caillon, and Jaime Gil Roca
Atmos. Chem. Phys., 16, 2659–2673,Short summary
Atmospheric nitrate is collected on the East Antarctic ice sheet. Nitrogen and oxygen stable isotopes and concentrations of nitrate are measured. Using a box model, we show that there is s systematic discrepancy between observations and model results. We suggest that this discrepancy probably results from unknown NOx chemistry above the Antarctic ice sheet. However, possible misconception in the stable isotope mass balance is not completely excluded.
T. A. Berhanu, J. Savarino, J. Erbland, W. C. Vicars, S. Preunkert, J. F. Martins, and M. S. Johnson
Atmos. Chem. Phys., 15, 11243–11256,Short summary
In this field study at Dome C, Antarctica, we investigated the effect of solar UV photolysis on the stable isotopes of nitrate in snow via comparison of two identical snow pits while exposing only one to solar UV. From the difference between the average isotopic fractionations calculated for each pit, we determined a purely photolytic nitrogen isotopic fractionation of -55.8‰, in good agreement with what has been recently determined in a laboratory study.
M. Saccon, A. Kornilova, L. Huang, S. Moukhtar, and J. Rudolph
Atmos. Chem. Phys., 15, 10825–10838,
E. D. Sofen, B. Alexander, E. J. Steig, M. H. Thiemens, S. A. Kunasek, H. M. Amos, A. J. Schauer, M. G. Hastings, J. Bautista, T. L. Jackson, L. E. Vogel, J. R. McConnell, D. R. Pasteris, and E. S. Saltzman
Atmos. Chem. Phys., 14, 5749–5769,
J. Wintel, E. Hösen, R. Koppmann, M. Krebsbach, A. Hofzumahaus, and F. Rohrer
Atmos. Chem. Phys., 13, 11059–11071,
F. A. Haumann, A. M. Batenburg, G. Pieterse, C. Gerbig, M. C. Krol, and T. Röckmann
Atmos. Chem. Phys., 13, 9401–9413,
J. Erbland, W. C. Vicars, J. Savarino, S. Morin, M. M. Frey, D. Frosini, E. Vince, and J. M. F. Martins
Atmos. Chem. Phys., 13, 6403–6419,
A. Guillon, K. Le Ménach, P.-M. Flaud, N. Marchand, H. Budzinski, and E. Villenave
Atmos. Chem. Phys., 13, 2703–2719,
D. Ceburnis, A. Garbaras, S. Szidat, M. Rinaldi, S. Fahrni, N. Perron, L. Wacker, S. Leinert, V. Remeikis, M. C. Facchini, A. S. H. Prevot, S. G. Jennings, M. Ramonet, and C. D. O'Dowd
Atmos. Chem. Phys., 11, 8593–8606,
A. M. Batenburg, S. Walter, G. Pieterse, I. Levin, M. Schmidt, A. Jordan, S. Hammer, C. Yver, and T. Röckmann
Atmos. Chem. Phys., 11, 6985–6999,
B. Tuzson, S. Henne, D. Brunner, M. Steinbacher, J. Mohn, B. Buchmann, and L. Emmenegger
Atmos. Chem. Phys., 11, 1685–1696,
Y. T. Fang, K. Koba, X. M. Wang, D. Z. Wen, J. Li, Y. Takebayashi, X. Y. Liu, and M. Yoh
Atmos. Chem. Phys., 11, 1313–1325,
S. S. Assonov, C. A. M. Brenninkmeijer, T. J. Schuck, and P. Taylor
Atmos. Chem. Phys., 10, 8575–8599,
U. Tsunogai, D. D. Komatsu, S. Daita, G. A. Kazemi, F. Nakagawa, I. Noguchi, and J. Zhang
Atmos. Chem. Phys., 10, 1809–1820,
M. M. Frey, J. Savarino, S. Morin, J. Erbland, and J. M. F. Martins
Atmos. Chem. Phys., 9, 8681–8696,
S. A. Vay, S. C. Tyler, Y. Choi, D. R. Blake, N. J. Blake, G. W. Sachse, G. S. Diskin, and H. B. Singh
Atmos. Chem. Phys., 9, 4973–4985,
Brass, M. and Röckmann, T.: Continuous-flow isotope ratio mass spectrometry method for carbon and hydrogen isotope measurements on atmospheric methane, Atmos. Meas. Tech., 3, 1707–1721, https://doi.org/10.5194/amt-3-1707-2010, 2010.
Bräunlich, M., Aballain, O., Marik, T., Jockel, P., Brenninkmeijer, C. A. M., Chappellaz, J., Barnola, J. M., Mulvaney, R., and Sturges, W. T.: Changes in the global atmospheric CH4 budget over the last decades inferred from δ13C and δD isotopic analysis of Antarctic firn air, J. Geophys. Res., 106, 20465–20481, https://doi.org/10.1029/2001JD900190, 2001.
Buizert, C., Martinerie, P., Petrenko, V. V., Severinghaus, J. P., Trudinger, C. M., Witrant, E., Rosen, J. L., Orsi, A. J., Rubino, M., Etheridge, D. M., Steele, L. P., Hogan, C., Laube, J. C., Sturges, W. T., Levchenko, V. A., Smith, A. M., Levin, I., Conway, T. J., Dlugokencky, E. J., Lang, P. M., Kawamura, K., Jenk, T. M., White, J. W. C., Sowers, T., Schwander, J., and Blunier, T.: Gas transport in firn: multiple-tracer characterisation and model intercomparison for NEEM, Northern Greenland, Atmos. Chem. Phys., 12, 4259–4277, https://doi.org/10.5194/acp-12-4259-2012, 2012.
Clark, I. D., Henderson, L., Chappellaz, J., Fisher, D., Koerner, R., Worthy, D. E. J., Kotzer, T., Norman, A.-L., and Barnola, J.-M.: CO2 isotopes as tracers of firn air diffusion and age in an Arctic ice cap with summer melting, Devon Island, Canada, J. Geophys. Res., 112, D01301, https://doi.org/10.1029/2006JD007471, 2007.
Craig, H. and Chou, C. C.: Methane – the Record in Polar Ice Cores, Geophys. Res. Lett., 9, 1221–1224, 1982.
Etheridge, D. M., Steele, L. P., Francey, R. J., and Langenfelds, R. L.: Atmospheric CH4 between 1000 AD and present: Evidence of antropogenic emissions and climatic variability, J. Geophys. Res., 103, 15979–15993, 1998.
Ferretti, D., Miller, J., White, J., Etheridge, D., Lassey, K., Lowe, D., Allan, B., MacFarling, C., Dreier, M., Trudinger, C., and Ommen, T. v.: Unexpected changes to the global CH4 budget over the past 2000 years, Science, 309, 864–867, https://doi.org/10.1126/science.1115193, 2005.
Francey, R., Manning, M. R., Allison, C. E., Coram, S. A., Etheridge, D. M., Langenfelds, R. L., Lowe, D. C., and Steele, L. P.: A history of δ13C in atmospheric CH4 from the Cape Grim Air Archive and Antarctic firn air, J. Geophys. Res., 104, 631–643, 1999.
Houweling, S., Dentener, F., Lelieveld, J., Walter, B., and Dlugokencky, E. J.: The modeling of tropospheric methane: How well can point measurements be reproduced by a global model?, J. Geophys. Res., 105, 8981–9002, 2000.
Houweling, S., Röckmann, T., Aben, I., Krol, M., and Keppler, F.: Atmospheric constraints on the global sources of methane from plants, Geophys. Res. Lett., 33, L15821, https://doi.org/10.1029/2006GL026162, 2006.
Houweling, S., van der Werf, G., Klein Goldewijk, K., Röckmann, T., and Aben, I.: Early anthropogenic emissions and the variation of CH4 and 13CH4 over the last millennium, Global Biogeochem. Cy., 22, GB1002, https://doi.org/10.1029/2007GB002961, 2008.
IPCC: Climate Change 2007: The Physical Science Basis – Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge Univ. Press, New York, 2007.
Levin, I., Veidt, C., Vaughn, B. H., Brailsford, G., Bromley, T., Heinz, R., Lowe, D., Miller, J. B., Poss, C., and White, J. W. C.: No inter-hemispheric δ13C(CH4) trend observed, Nature, 486, E3–E4, 2012.
MacFarling Meure, C., Etheridge, D., Trudinger, C., Steele, P., Langenfelds, R., Ommen, T. v., Smith, A., and Elkins, J.: Law Dome CO2, CH4 and N2O ice core records extended to 2000 years BP Geophys. Res. Lett., 33, L14810, https://doi.org/10.1029/2006GL026152, 2006.
Martinerie, P., Nourtier-Mazauric, E., Barnola, J.-M., Sturges, W. T., Worton, D. R., Atlas, E., Gohar, L. K., Shine, K. P., and Brasseur, G. P.: Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn, Atmos. Chem. Phys., 9, 3911–3934, https://doi.org/10.5194/acp-9-3911-2009, 2009.
Miller, J. B., Mack, K. A., Dissly, R., White, J. W. C., Dlugokencky, E. J., and Tans, P. P.: Development of analytical methods and measurements of δ13C in atmospheric CH4 from the NOAA/CMDL global air sampling network, J. Geophys. Res., 107, 4178, https://doi.org/10.1029/2001JD000630, 2002.
Mikaloff Fletcher, S. E., Tans, P. P., Bruhwiler, L. M., Miller, J. B., and Heimann, M.: CH4 sources estimated from atmospheric observations of CH4 and its 13C/12C isotopic ratios: 1.Inverse modeling of source processes, Global Biogeochem. Cy., 18, GB4004, https://doi.org/10.1029/2004GB002223, 2004a.
Mikaloff Fletcher, S. E., Tans, P. P., Bruhwiler, L. M., Miller, J. B., and Heimann, M.: CH4 sources estimated from atmospheric observations of CH4 and its 13C/12C isotopic ratios: 2. Inverse modeling of CH4 fluxes from geographical regions, Global Biogeochem. Cy., 18, GB4005, https://doi.org/10.1029/2004GB002224, 2004b.
Monteil, G., Houweling, S., Dlugockenky, E. J., Maenhout, G., Vaughn, B. H., White, J. W. C., and Rockmann, T.: Interpreting methane variations in the past two decades using measurements of CH4 mixing ratio and isotopic composition, Atmos. Chem. Phys., 11, 9141–9153, https://doi.org/10.5194/acp-11-9141-2011, 2011.
Quay, P., Stutsman, J., Wilbur, D., Snover, A., Dlugokencky, E., and Brown, T.: The isotopic composition of atmospheric CH4, Global Biogeochem. Cy., 13, 445–461, https://doi.org/10.1029/1998GB900006, 1999.
Rommelaere, V., Arnaud, L., and Barnola, J.-M.: Reconstructing recent atmospheric trace gas concentrations from polar firn and bubbly ice data by inverse methods, J. Geophys. Res., 102, 30069–30083, 1997.
Sapart, C. J., van der Veen, C., Vigano, I., Brass,, M., van de Wal, R. S. W., Bock, M., Fischer, H., Sowers, T., Buizert, C., Sperlich, P., Blunier, T., Behrens, M., Schmitt, J., Seth, B., and Röckmann, T.: Simultaneous stable isotope analysis of methane and nitrous oxide on ice core samples, Atmos. Meas. Tech., 4, 2607–2618, https://doi.org/10.5194/amt-4-2607-2011, 2011.
Sapart, C. J., Monteil, G., Prokopiou, M., Van de Wal, R. S. W., Kaplan, J. O., Sperlich, P., Krumhardt, K. M., Van der Veen, C., Houweling, S., Krol, M. C., Blunier, T., Sowers, T., Martinerie, P., Witrant, E., Dahl-Jensen, D., and Röckmann, T.: Natural and anthropogenic variations in methane sources during the past 2 millennia, Nature, 490, 85–88, https://doi.org/10.1038/nature11461, 2012.
Schwander, J., Barnola, J. M., Andrie, C., Leuenberger, M., Ludin, A., Raynaud, D., and Stauffer, B.: The Age of the Air in the Firn and the Ice at Summit, Greenland, J. Geophys. Res., 98, 2831, https://doi.org/10.1029/92JD02383, 1993.
Severinghaus, J. P., Grachev, A., and Battle, M.: Thermal fractionation of air in polar firn by seasonal temperature gradients, Geochem. Geophys. Geosyst., 2, 1048, https://doi.org/10.1029/2000GC000146, 2001.
Schmitt, J., Seth, B., Bock, M., van der Veen, C., Möller, L., Sapart, C. J., Prokopiou, M., Sowers, T., Röckmann, T., and Fischer, H.: On the interference of 86Kr2+ during carbon isotope analysis of atmospheric methane using continuous flow combustion – isotope ratio mass spectrometry, Atmos. Meas. Tech. Discuss., 6, 1409–1460, https://doi.org/10.5194/amtd-6-1409-2013, 2013.
Sowers, T., Bender, M., and Raynaud, D.: Elemental and isotopic composition of occluded O2 and N2 in polar ice, J. Geophys. Res., 94, 5137–5150, 1989.
Sowers, T., Bernard, S., Aballain, O., Chappellaz, J., Barnola, J. M., and Marik, T.: Records of the δ13C of atmospheric CH4 over the last 2 centuries as recorded in Antarctic snow and ice, Global Biogeochem. Cy., 19, 493–503, https://doi.org/10.1029/2004GB002408, 2005.
Spahni, R., Schwander, J., Flückiger, J., Stauffer, B., Chappellaz, J., and Raynaud, D.: The attenuation of fast atmospheric CH4 variations recorded in polar ice cores, Geophys. Res. Lett., 30, 1571, https://doi.org/10.1029/2003GL017093, 2003.
Stauffer, B., Schwander, J., and Oeschger, H.: Enclosure of air during metamorphosis of dry firn to ice, Ann. Glaciol., 6, 108–112, 1985.
Tans, P. P.: A note on isotopic ratios and the global atmospheric methane budget, Global Biogeochem. Cy., 11, 77–81, 1997.
Trudinger, C. M., Enting, I. G., Etheridge, D. M., Francey, R. J., Levchenko, V. A., Steele, L. P., Raynaud, D., and Arnaud, L.: Modeling air movement and bubble trapping in firn, J. Geophys. Res.-Atmos., 102, 6747–6763, 1997.
Tyler, S. C., Rice, A. L., and Ajie, H. O.: Stable isotope ratios in atmospheric CH4 : Implications for seasonal sources and sinks, J. Geophys. Res., 112, D03303, https://doi.org/10.1029/2006JD007231, 2007.
Wang, Z., Chappellaz, J., Martinerie, P., Park, K., Petrenko, V., Witrant, E., Emmons, L. K., Blunier, T., Brenninkmeijer, C. A. M., and Mak, J. E.: The isotopic record of Northern Hemisphere atmospheric carbon monoxide since 1950: implications for the CO budget, Atmos. Chem. Phys., 12, 4365–4377, https://doi.org/10.5194/acp-12-4365-2012, 2012.
Witrant, E., Martinerie, P., Hogan, C., Laube, J. C., Kawamura, K., Capron, E., Montzka, S. A., Dlugokencky, E. J., Etheridge, D., Blunier, T., and Sturges, W. T.: A new multi-gas constrained model of trace gas non-homogeneous transport in firn: evaluation and behaviour at eleven polar sites, Atmos. Chem. Phys., 12, 11465–11483, https://doi.org/10.5194/acp-12-11465-2012, 2012.