Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes
Arctic soils contain a large pool of terrestrial C and are of interest due to their potential for releasing significant carbon dioxide (CO2) and methane (CH4) to the atmosphere. Due to substantial landscape heterogeneity, predicting ecosystem-scale CH4 and CO2 production is challenging. This study a...
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ftcdlib:oai:escholarship.org/ark:/13030/qt3603b7z7 2023-05-15T14:55:53+02:00 Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes Throckmorton, HM Heikoop, JM Newman, BD Altmann, GL Conrad, MS Muss, JD Perkins, GB Smith, LJ Torn, MS Wullschleger, SD Wilson, CJ 1893 - 1910 2015-11-01 application/pdf https://escholarship.org/uc/item/3603b7z7 unknown eScholarship, University of California qt3603b7z7 https://escholarship.org/uc/item/3603b7z7 public Global Biogeochemical Cycles, vol 29, iss 11 Meteorology & Atmospheric Sciences Atmospheric Sciences Geochemistry Oceanography article 2015 ftcdlib 2021-06-21T17:05:33Z Arctic soils contain a large pool of terrestrial C and are of interest due to their potential for releasing significant carbon dioxide (CO2) and methane (CH4) to the atmosphere. Due to substantial landscape heterogeneity, predicting ecosystem-scale CH4 and CO2 production is challenging. This study assessed dissolved inorganic carbon (DIC = Σ (total) dissolved CO2) and CH4 in watershed drainages in Barrow, Alaska as critical convergent zones of regional geochemistry, substrates, and nutrients. In July and September of 2013, surface waters and saturated subsurface pore waters were collected from 17 drainages. Based on simultaneous DIC and CH4 cycling, we synthesized isotopic and geochemical methods to develop a subsurface CH4 and DIC balance by estimating mechanisms of CH4 and DIC production and transport pathways and oxidation of subsurface CH4. We observed a shift from acetoclastic (July) toward hydrogenotropic (September) methanogenesis at sites located toward the end of major freshwater drainages, adjacent to salty estuarine waters, suggesting an interesting landscape-scale effect on CH4 production mechanism. The majority of subsurface CH4 was transported upward by plant-mediated transport and ebullition, predominantly bypassing the potential for CH4 oxidation. Thus, surprisingly, CH4 oxidation only consumed approximately 2.51 ± 0.82% (July) and 0.79 ± 0.79% (September) of CH4 produced at the frost table, contributing to <0.1% of DIC production. DIC was primarily produced from respiration, with iron and organic matter serving as likely e- acceptors. This work highlights the importance of spatial and temporal variability of CH4 production at the watershed scale and suggests broad scale investigations are required to build better regional or pan-Arctic representations of CH4 and CO2 production. Article in Journal/Newspaper Arctic Barrow Tundra Alaska University of California: eScholarship Arctic |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Meteorology & Atmospheric Sciences Atmospheric Sciences Geochemistry Oceanography |
spellingShingle |
Meteorology & Atmospheric Sciences Atmospheric Sciences Geochemistry Oceanography Throckmorton, HM Heikoop, JM Newman, BD Altmann, GL Conrad, MS Muss, JD Perkins, GB Smith, LJ Torn, MS Wullschleger, SD Wilson, CJ Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes |
topic_facet |
Meteorology & Atmospheric Sciences Atmospheric Sciences Geochemistry Oceanography |
description |
Arctic soils contain a large pool of terrestrial C and are of interest due to their potential for releasing significant carbon dioxide (CO2) and methane (CH4) to the atmosphere. Due to substantial landscape heterogeneity, predicting ecosystem-scale CH4 and CO2 production is challenging. This study assessed dissolved inorganic carbon (DIC = Σ (total) dissolved CO2) and CH4 in watershed drainages in Barrow, Alaska as critical convergent zones of regional geochemistry, substrates, and nutrients. In July and September of 2013, surface waters and saturated subsurface pore waters were collected from 17 drainages. Based on simultaneous DIC and CH4 cycling, we synthesized isotopic and geochemical methods to develop a subsurface CH4 and DIC balance by estimating mechanisms of CH4 and DIC production and transport pathways and oxidation of subsurface CH4. We observed a shift from acetoclastic (July) toward hydrogenotropic (September) methanogenesis at sites located toward the end of major freshwater drainages, adjacent to salty estuarine waters, suggesting an interesting landscape-scale effect on CH4 production mechanism. The majority of subsurface CH4 was transported upward by plant-mediated transport and ebullition, predominantly bypassing the potential for CH4 oxidation. Thus, surprisingly, CH4 oxidation only consumed approximately 2.51 ± 0.82% (July) and 0.79 ± 0.79% (September) of CH4 produced at the frost table, contributing to <0.1% of DIC production. DIC was primarily produced from respiration, with iron and organic matter serving as likely e- acceptors. This work highlights the importance of spatial and temporal variability of CH4 production at the watershed scale and suggests broad scale investigations are required to build better regional or pan-Arctic representations of CH4 and CO2 production. |
format |
Article in Journal/Newspaper |
author |
Throckmorton, HM Heikoop, JM Newman, BD Altmann, GL Conrad, MS Muss, JD Perkins, GB Smith, LJ Torn, MS Wullschleger, SD Wilson, CJ |
author_facet |
Throckmorton, HM Heikoop, JM Newman, BD Altmann, GL Conrad, MS Muss, JD Perkins, GB Smith, LJ Torn, MS Wullschleger, SD Wilson, CJ |
author_sort |
Throckmorton, HM |
title |
Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes |
title_short |
Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes |
title_full |
Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes |
title_fullStr |
Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes |
title_full_unstemmed |
Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes |
title_sort |
pathways and transformations of dissolved methane and dissolved inorganic carbon in arctic tundra watersheds: evidence from analysis of stable isotopes |
publisher |
eScholarship, University of California |
publishDate |
2015 |
url |
https://escholarship.org/uc/item/3603b7z7 |
op_coverage |
1893 - 1910 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Barrow Tundra Alaska |
genre_facet |
Arctic Barrow Tundra Alaska |
op_source |
Global Biogeochemical Cycles, vol 29, iss 11 |
op_relation |
qt3603b7z7 https://escholarship.org/uc/item/3603b7z7 |
op_rights |
public |
_version_ |
1766327897121882112 |