Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air
The atmospheric trend of methane isotopic ratios since the mid-20th century has been reconstructed from Antarctic firn air. High volume air samples were extracted at several depth levels at two sites in East Antarctica. Methane concentration and its 13C/12C and D/H ratios were determined by gas chro...
Published in: | Journal of Geophysical Research: Atmospheres |
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ftnerc:oai:nora.nerc.ac.uk:18473 2023-05-15T13:45:12+02:00 Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air Bräunlich, Maya Aballain, Olivier Marik, Thomas Jöckel, Patrick Brenninkmeijer, Carl A.M. Chappellaz, Jerome Barnola, Jean-Marc Mulvaney, Robert Sturges, William T. 2001-09 http://nora.nerc.ac.uk/id/eprint/18473/ https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2001JD900190 unknown American Geophysical Union Bräunlich, Maya; Aballain, Olivier; Marik, Thomas; Jöckel, Patrick; Brenninkmeijer, Carl A.M.; Chappellaz, Jerome; Barnola, Jean-Marc; Mulvaney, Robert orcid:0000-0002-5372-8148 Sturges, William T. 2001 Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air. Journal of Geophysical Research, 106 (D17). 20465-20481. https://doi.org/10.1029/2001JD900190 <https://doi.org/10.1029/2001JD900190> Chemistry Publication - Article PeerReviewed 2001 ftnerc https://doi.org/10.1029/2001JD900190 2023-02-04T19:31:47Z The atmospheric trend of methane isotopic ratios since the mid-20th century has been reconstructed from Antarctic firn air. High volume air samples were extracted at several depth levels at two sites in East Antarctica. Methane concentration and its 13C/12C and D/H ratios were determined by gas chromatography, mass spectrometry, and infrared spectroscopy. A firn air transport model was applied to reconstruct past atmospheric trends in methane and its isotopic composition. By subsequent application of an atmospheric model, changes in methane sources and OH sink compatible with the past atmospheric trends are explored. In step with increasing methane mixing ratios, δ 13C increased by ∼1.7‰0 over the last 50 years. These changes mainly reflect a shift in relative source strength toward the heavier anthropogenic methane source, such as biomass burning and methane of nonbiological origin. The δD (CH4) showed a period of decline between the 1950s and 1975, followed by a gradual increase of 0.55‰/yr, also toward the heavier anthropogenic source. Dependent on possible changes in the OH sink, to which δD of methane is very sensitive, the inferred isotopic trends of δ 13C and δD over the last 50 years constrain the relationship between natural and anthropogenic sources over the last century. The observed δD minimum around 1975 suggests that the slowing down in the methane source growth took place during this period. Article in Journal/Newspaper Antarc* Antarctic Antarctica East Antarctica Natural Environment Research Council: NERC Open Research Archive Antarctic East Antarctica Journal of Geophysical Research: Atmospheres 106 D17 20465 20481 |
institution |
Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
topic |
Chemistry |
spellingShingle |
Chemistry Bräunlich, Maya Aballain, Olivier Marik, Thomas Jöckel, Patrick Brenninkmeijer, Carl A.M. Chappellaz, Jerome Barnola, Jean-Marc Mulvaney, Robert Sturges, William T. Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air |
topic_facet |
Chemistry |
description |
The atmospheric trend of methane isotopic ratios since the mid-20th century has been reconstructed from Antarctic firn air. High volume air samples were extracted at several depth levels at two sites in East Antarctica. Methane concentration and its 13C/12C and D/H ratios were determined by gas chromatography, mass spectrometry, and infrared spectroscopy. A firn air transport model was applied to reconstruct past atmospheric trends in methane and its isotopic composition. By subsequent application of an atmospheric model, changes in methane sources and OH sink compatible with the past atmospheric trends are explored. In step with increasing methane mixing ratios, δ 13C increased by ∼1.7‰0 over the last 50 years. These changes mainly reflect a shift in relative source strength toward the heavier anthropogenic methane source, such as biomass burning and methane of nonbiological origin. The δD (CH4) showed a period of decline between the 1950s and 1975, followed by a gradual increase of 0.55‰/yr, also toward the heavier anthropogenic source. Dependent on possible changes in the OH sink, to which δD of methane is very sensitive, the inferred isotopic trends of δ 13C and δD over the last 50 years constrain the relationship between natural and anthropogenic sources over the last century. The observed δD minimum around 1975 suggests that the slowing down in the methane source growth took place during this period. |
format |
Article in Journal/Newspaper |
author |
Bräunlich, Maya Aballain, Olivier Marik, Thomas Jöckel, Patrick Brenninkmeijer, Carl A.M. Chappellaz, Jerome Barnola, Jean-Marc Mulvaney, Robert Sturges, William T. |
author_facet |
Bräunlich, Maya Aballain, Olivier Marik, Thomas Jöckel, Patrick Brenninkmeijer, Carl A.M. Chappellaz, Jerome Barnola, Jean-Marc Mulvaney, Robert Sturges, William T. |
author_sort |
Bräunlich, Maya |
title |
Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air |
title_short |
Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air |
title_full |
Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air |
title_fullStr |
Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air |
title_full_unstemmed |
Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air |
title_sort |
changes in the global atmospheric methane budget over the last decades inferred from 13c and d isotopic analysis of antarctic firn air |
publisher |
American Geophysical Union |
publishDate |
2001 |
url |
http://nora.nerc.ac.uk/id/eprint/18473/ https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2001JD900190 |
geographic |
Antarctic East Antarctica |
geographic_facet |
Antarctic East Antarctica |
genre |
Antarc* Antarctic Antarctica East Antarctica |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica |
op_relation |
Bräunlich, Maya; Aballain, Olivier; Marik, Thomas; Jöckel, Patrick; Brenninkmeijer, Carl A.M.; Chappellaz, Jerome; Barnola, Jean-Marc; Mulvaney, Robert orcid:0000-0002-5372-8148 Sturges, William T. 2001 Changes in the global atmospheric methane budget over the last decades inferred from 13C and D isotopic analysis of Antarctic firn air. Journal of Geophysical Research, 106 (D17). 20465-20481. https://doi.org/10.1029/2001JD900190 <https://doi.org/10.1029/2001JD900190> |
op_doi |
https://doi.org/10.1029/2001JD900190 |
container_title |
Journal of Geophysical Research: Atmospheres |
container_volume |
106 |
container_issue |
D17 |
container_start_page |
20465 |
op_container_end_page |
20481 |
_version_ |
1766216677264982016 |