Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska
Arctic tundra soils store a large quantity of organic carbon that is susceptible to decomposition and release to the atmosphere as methane (CH 4 ) and carbon dioxide (CO 2 ) under a warming climate. Anaerobic processes that generate CH 4 and CO 2 remain unclear because previous studies have focused...
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Online Access: | http://www.osti.gov/servlets/purl/1235813 https://www.osti.gov/biblio/1235813 https://doi.org/10.1002/2015JG003147 |
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ftosti:oai:osti.gov:1235813 2023-07-30T04:01:22+02:00 Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska Herndon, Elizabeth M. Mann, Benjamin F. Chowdhury, Taniya Roy Wullschleger, Stan D. Graham, David E. Liang, Liyuan Gu, Baohua Yang, Ziming 2021-07-19 application/pdf http://www.osti.gov/servlets/purl/1235813 https://www.osti.gov/biblio/1235813 https://doi.org/10.1002/2015JG003147 unknown http://www.osti.gov/servlets/purl/1235813 https://www.osti.gov/biblio/1235813 https://doi.org/10.1002/2015JG003147 doi:10.1002/2015JG003147 54 ENVIRONMENTAL SCIENCES 2021 ftosti https://doi.org/10.1002/2015JG003147 2023-07-11T09:04:41Z Arctic tundra soils store a large quantity of organic carbon that is susceptible to decomposition and release to the atmosphere as methane (CH 4 ) and carbon dioxide (CO 2 ) under a warming climate. Anaerobic processes that generate CH 4 and CO 2 remain unclear because previous studies have focused on aerobic decomposition pathways. To predict releases of CO 2 and CH 4 from tundra soils, it is necessary to identify pathways of soil organic matter decomposition under the anoxic conditions that are prevalent in Arctic ecosystems. Here molecular and spectroscopic techniques were used to monitor biological degradation of water-extractable organic carbon (WEOC) during anoxic incubation of tundra soils from a region of continuous permafrost in northern Alaska. Organic and mineral soils from the tundra active layer were incubated at –2, +4, or +8°C for up to 60 days to mimic the short-term thaw season. Results suggest that, under anoxic conditions, fermentation converted complex organic molecules into simple organic acids that were used in concomitant Fe-reduction and acetoclastic methanogenesis reactions. Nonaromatic compounds increased over time as WEOC increased. Organic acid metabolites initially accumulated in soils but were mostly depleted by day 60 because organic acids were consumed to produce Fe(II), CO 2 , and CH 4 . We conclude that fermentation of nonprotected organic matter facilitates methanogenesis and Fe reduction reactions, and that the proportion of organic acids consumed by methanogenesis increases relative to Fe reduction with increasing temperature. As a result, the decomposition pathways observed in this study are important to consider in numerical modeling of greenhouse gas production in the Arctic. Other/Unknown Material Arctic Barrow permafrost Tundra Alaska SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Arctic Journal of Geophysical Research: Biogeosciences 120 11 2345 2359 |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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54 ENVIRONMENTAL SCIENCES |
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54 ENVIRONMENTAL SCIENCES Herndon, Elizabeth M. Mann, Benjamin F. Chowdhury, Taniya Roy Wullschleger, Stan D. Graham, David E. Liang, Liyuan Gu, Baohua Yang, Ziming Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska |
topic_facet |
54 ENVIRONMENTAL SCIENCES |
description |
Arctic tundra soils store a large quantity of organic carbon that is susceptible to decomposition and release to the atmosphere as methane (CH 4 ) and carbon dioxide (CO 2 ) under a warming climate. Anaerobic processes that generate CH 4 and CO 2 remain unclear because previous studies have focused on aerobic decomposition pathways. To predict releases of CO 2 and CH 4 from tundra soils, it is necessary to identify pathways of soil organic matter decomposition under the anoxic conditions that are prevalent in Arctic ecosystems. Here molecular and spectroscopic techniques were used to monitor biological degradation of water-extractable organic carbon (WEOC) during anoxic incubation of tundra soils from a region of continuous permafrost in northern Alaska. Organic and mineral soils from the tundra active layer were incubated at –2, +4, or +8°C for up to 60 days to mimic the short-term thaw season. Results suggest that, under anoxic conditions, fermentation converted complex organic molecules into simple organic acids that were used in concomitant Fe-reduction and acetoclastic methanogenesis reactions. Nonaromatic compounds increased over time as WEOC increased. Organic acid metabolites initially accumulated in soils but were mostly depleted by day 60 because organic acids were consumed to produce Fe(II), CO 2 , and CH 4 . We conclude that fermentation of nonprotected organic matter facilitates methanogenesis and Fe reduction reactions, and that the proportion of organic acids consumed by methanogenesis increases relative to Fe reduction with increasing temperature. As a result, the decomposition pathways observed in this study are important to consider in numerical modeling of greenhouse gas production in the Arctic. |
author |
Herndon, Elizabeth M. Mann, Benjamin F. Chowdhury, Taniya Roy Wullschleger, Stan D. Graham, David E. Liang, Liyuan Gu, Baohua Yang, Ziming |
author_facet |
Herndon, Elizabeth M. Mann, Benjamin F. Chowdhury, Taniya Roy Wullschleger, Stan D. Graham, David E. Liang, Liyuan Gu, Baohua Yang, Ziming |
author_sort |
Herndon, Elizabeth M. |
title |
Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska |
title_short |
Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska |
title_full |
Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska |
title_fullStr |
Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska |
title_full_unstemmed |
Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska |
title_sort |
pathways of anaerobic organic matter decomposition in tundra soils from barrow, alaska |
publishDate |
2021 |
url |
http://www.osti.gov/servlets/purl/1235813 https://www.osti.gov/biblio/1235813 https://doi.org/10.1002/2015JG003147 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Barrow permafrost Tundra Alaska |
genre_facet |
Arctic Barrow permafrost Tundra Alaska |
op_relation |
http://www.osti.gov/servlets/purl/1235813 https://www.osti.gov/biblio/1235813 https://doi.org/10.1002/2015JG003147 doi:10.1002/2015JG003147 |
op_doi |
https://doi.org/10.1002/2015JG003147 |
container_title |
Journal of Geophysical Research: Biogeosciences |
container_volume |
120 |
container_issue |
11 |
container_start_page |
2345 |
op_container_end_page |
2359 |
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1772812102066503680 |