Deep Sediment-Sourced Methane Contribution to Shallow Sediment Organic Carbon: Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico
Coastal methane hydrate deposits are globally abundant. There is a need to understand the deep sediment sourced methane energy contribution to shallow sediment carbon relative to terrestrial sources and phytoplankton. Shallow sediment and porewater samples were collected from Atwater Valley, Texas-L...
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ftmdpi:oai:mdpi.com:/1996-1073/8/3/1561/ 2023-08-20T04:07:58+02:00 Deep Sediment-Sourced Methane Contribution to Shallow Sediment Organic Carbon: Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico Richard Coffin Christopher Osburn Rebecca Plummer Joseph Smith Paula Rose Kenneth Grabowski 2015-02-18 application/pdf https://doi.org/10.3390/en8031561 EN eng Multidisciplinary Digital Publishing Institute https://dx.doi.org/10.3390/en8031561 https://creativecommons.org/licenses/by/4.0/ Energies; Volume 8; Issue 3; Pages: 1561-1583 methane advection geochemistry carbon isotopes sediment carbon Text 2015 ftmdpi https://doi.org/10.3390/en8031561 2023-07-31T20:41:59Z Coastal methane hydrate deposits are globally abundant. There is a need to understand the deep sediment sourced methane energy contribution to shallow sediment carbon relative to terrestrial sources and phytoplankton. Shallow sediment and porewater samples were collected from Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico near a seafloor mound feature identified in geophysical surveys as an elevated bottom seismic reflection. Geochemical data revealed off-mound methane diffusion and active fluid advection on-mound. Gas composition (average methane/ethane ratio ~11,000) and isotope ratios of methane on the mound (average δ13CCH4(g) = −71.2‰; D14CCH4(g) = −961‰) indicate a deep sediment, microbial source. Depleted sediment organic carbon values on mound (δ13CSOC = −25.8‰; D14CSOC = −930‰) relative to off-mound (δ13CSOC = −22.5‰; D14CSOC = −629‰) suggest deep sourced ancient carbon is incorporated into shallow sediment organic matter. Porewater and sediment data indicate inorganic carbon fixed during anaerobic oxidation of methane is a dominant contributor to on-mound shallow sediment organic carbon cycling. A simple stable carbon isotope mass balance suggests carbon fixation of dissolved inorganic carbon (DIC) associated with anaerobic oxidation of hydrate-sourced CH4 contributes up to 85% of shallow sediment organic carbon. Text Methane hydrate MDPI Open Access Publishing Energies 8 3 1561 1583 |
institution |
Open Polar |
collection |
MDPI Open Access Publishing |
op_collection_id |
ftmdpi |
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English |
topic |
methane advection geochemistry carbon isotopes sediment carbon |
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methane advection geochemistry carbon isotopes sediment carbon Richard Coffin Christopher Osburn Rebecca Plummer Joseph Smith Paula Rose Kenneth Grabowski Deep Sediment-Sourced Methane Contribution to Shallow Sediment Organic Carbon: Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico |
topic_facet |
methane advection geochemistry carbon isotopes sediment carbon |
description |
Coastal methane hydrate deposits are globally abundant. There is a need to understand the deep sediment sourced methane energy contribution to shallow sediment carbon relative to terrestrial sources and phytoplankton. Shallow sediment and porewater samples were collected from Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico near a seafloor mound feature identified in geophysical surveys as an elevated bottom seismic reflection. Geochemical data revealed off-mound methane diffusion and active fluid advection on-mound. Gas composition (average methane/ethane ratio ~11,000) and isotope ratios of methane on the mound (average δ13CCH4(g) = −71.2‰; D14CCH4(g) = −961‰) indicate a deep sediment, microbial source. Depleted sediment organic carbon values on mound (δ13CSOC = −25.8‰; D14CSOC = −930‰) relative to off-mound (δ13CSOC = −22.5‰; D14CSOC = −629‰) suggest deep sourced ancient carbon is incorporated into shallow sediment organic matter. Porewater and sediment data indicate inorganic carbon fixed during anaerobic oxidation of methane is a dominant contributor to on-mound shallow sediment organic carbon cycling. A simple stable carbon isotope mass balance suggests carbon fixation of dissolved inorganic carbon (DIC) associated with anaerobic oxidation of hydrate-sourced CH4 contributes up to 85% of shallow sediment organic carbon. |
format |
Text |
author |
Richard Coffin Christopher Osburn Rebecca Plummer Joseph Smith Paula Rose Kenneth Grabowski |
author_facet |
Richard Coffin Christopher Osburn Rebecca Plummer Joseph Smith Paula Rose Kenneth Grabowski |
author_sort |
Richard Coffin |
title |
Deep Sediment-Sourced Methane Contribution to Shallow Sediment Organic Carbon: Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico |
title_short |
Deep Sediment-Sourced Methane Contribution to Shallow Sediment Organic Carbon: Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico |
title_full |
Deep Sediment-Sourced Methane Contribution to Shallow Sediment Organic Carbon: Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico |
title_fullStr |
Deep Sediment-Sourced Methane Contribution to Shallow Sediment Organic Carbon: Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico |
title_full_unstemmed |
Deep Sediment-Sourced Methane Contribution to Shallow Sediment Organic Carbon: Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico |
title_sort |
deep sediment-sourced methane contribution to shallow sediment organic carbon: atwater valley, texas-louisiana shelf, gulf of mexico |
publisher |
Multidisciplinary Digital Publishing Institute |
publishDate |
2015 |
url |
https://doi.org/10.3390/en8031561 |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
Energies; Volume 8; Issue 3; Pages: 1561-1583 |
op_relation |
https://dx.doi.org/10.3390/en8031561 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3390/en8031561 |
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Energies |
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8 |
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3 |
container_start_page |
1561 |
op_container_end_page |
1583 |
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1774719962590478336 |