Estimating the Impact of Seep Methane Oxidation on Ocean pH and Dissolved Inorganic Radiocarbon Along the U.S. Mid-Atlantic Bight

Fenix Garcia-Tigreros; Mihai Leonte; Carolyn D. Ruppel; Angel Ruiz-Angulo; Dong Joo Joung; Benjamin Young; John D. Kessler

doi:10.1029/2019JG005621

Estimating the Impact of Seep Methane Oxidation on Ocean pH and Dissolved Inorganic Radiocarbon Along the U.S. Mid-Atlantic Bight

Fenix Garcia-Tigreros^*, Mihai Leonte, Carolyn D. Ruppel, Angel Ruiz-Angulo, Dong Joo Joung, Benjamin Young, John D. Kessler

^*Corresponding author for this work

Faculty of Earth Sciences

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

Ongoing ocean warming can release methane (CH₄) currently stored in ocean sediments as free gas and gas hydrates. Once dissolved in ocean waters, this CH₄ can be oxidized to carbon dioxide (CO₂). While it has been hypothesized that the CO₂ produced from aerobic CH₄ oxidation could enhance ocean acidification, a previous study conducted in Hudson Canyon shows that CH₄ oxidation has a small short-term influence on ocean pH and dissolved inorganic radiocarbon. Here we expand upon that investigation to assess the impact of widespread CH₄ seepage on CO₂ chemistry and possible accumulation of this carbon injection along 234 km of the U.S. Mid-Atlantic Bight. Consistent with the estimates from Hudson Canyon, we demonstrate that a small fraction of ancient CH₄-derived carbon is being assimilated into the dissolved inorganic radiocarbon (mean fraction of 0.5 ± 0.4%). The areas with the highest fractions of ancient carbon coincide with elevated CH₄ concentration and active gas seepage. This suggests that aerobic CH₄ oxidation has a greater influence on the dissolved inorganic pool in areas where CH₄ concentrations are locally elevated, instead of displaying a cumulative effect downcurrent from widespread groupings of CH₄ seeps. A first-order approximation of the input rate of ancient-derived dissolved inorganic carbon (DIC) into the waters overlying the northern U.S. Mid-Atlantic Bight further suggests that oxidation of ancient CH₄-derived carbon is not negligible on the global scale and could contribute to deepwater acidification over longer time scales.

Original language	English
Article number	e2019JG005621
Journal	Journal of Geophysical Research: Biogeosciences
Volume	126
Issue number	1
DOIs	https://doi.org/10.1029/2019JG005621
Publication status	Published - Jan 2021

Bibliographical note

Funding Information:
This study was sponsored by U.S. Department of Energy (DE‐FE0028980, awarded to J. D. K; DE‐FE0026195 interagency agreement with C. D. R.). We thank the crew of the for their support, G. Hatcher, J. Borden, and M. Martini of the USGS for assistance with the LADCP, and Zach Bunnell, Lillian Henderson, and Allison Laubach for additional support at sea. The quality of this manuscript was greatly improved thanks to the insightful comments of the two reviewers and P. Hart. Any use of trade, firm or product name is for descriptive purposes only and does not imply endorsement by the U.S. Government. R/V Hugh R. Sharp

Funding Information:
This study was sponsored by U.S. Department of Energy (DE-FE0028980, awarded to J. D. K; DE-FE0026195 interagency agreement with C. D. R.). We thank the crew of the R/V Hugh R. Sharp for their support, G. Hatcher, J. Borden, and M. Martini of the USGS for assistance with the LADCP, and Zach Bunnell, Lillian Henderson, and Allison Laubach for additional support at sea. The quality of this manuscript was greatly improved thanks to the insightful comments of the two reviewers and P. Hart. Any use of trade, firm or product name is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.

Other keywords

climate change
DIC
methane
ocean acidification
radiocarbon
U.S Mid-Atlantic Bight

Access to Document

10.1029/2019JG005621

Cite this

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title = "Estimating the Impact of Seep Methane Oxidation on Ocean pH and Dissolved Inorganic Radiocarbon Along the U.S. Mid-Atlantic Bight",

abstract = "Ongoing ocean warming can release methane (CH4) currently stored in ocean sediments as free gas and gas hydrates. Once dissolved in ocean waters, this CH4 can be oxidized to carbon dioxide (CO2). While it has been hypothesized that the CO2 produced from aerobic CH4 oxidation could enhance ocean acidification, a previous study conducted in Hudson Canyon shows that CH4 oxidation has a small short-term influence on ocean pH and dissolved inorganic radiocarbon. Here we expand upon that investigation to assess the impact of widespread CH4 seepage on CO2 chemistry and possible accumulation of this carbon injection along 234 km of the U.S. Mid-Atlantic Bight. Consistent with the estimates from Hudson Canyon, we demonstrate that a small fraction of ancient CH4-derived carbon is being assimilated into the dissolved inorganic radiocarbon (mean fraction of 0.5 ± 0.4%). The areas with the highest fractions of ancient carbon coincide with elevated CH4 concentration and active gas seepage. This suggests that aerobic CH4 oxidation has a greater influence on the dissolved inorganic pool in areas where CH4 concentrations are locally elevated, instead of displaying a cumulative effect downcurrent from widespread groupings of CH4 seeps. A first-order approximation of the input rate of ancient-derived dissolved inorganic carbon (DIC) into the waters overlying the northern U.S. Mid-Atlantic Bight further suggests that oxidation of ancient CH4-derived carbon is not negligible on the global scale and could contribute to deepwater acidification over longer time scales.",

keywords = "climate change, DIC, methane, ocean acidification, radiocarbon, U.S Mid-Atlantic Bight",

author = "Fenix Garcia-Tigreros and Mihai Leonte and Ruppel, {Carolyn D.} and Angel Ruiz-Angulo and Joung, {Dong Joo} and Benjamin Young and Kessler, {John D.}",

note = "Funding Information: This study was sponsored by U.S. Department of Energy (DE‐FE0028980, awarded to J. D. K; DE‐FE0026195 interagency agreement with C. D. R.). We thank the crew of the for their support, G. Hatcher, J. Borden, and M. Martini of the USGS for assistance with the LADCP, and Zach Bunnell, Lillian Henderson, and Allison Laubach for additional support at sea. The quality of this manuscript was greatly improved thanks to the insightful comments of the two reviewers and P. Hart. Any use of trade, firm or product name is for descriptive purposes only and does not imply endorsement by the U.S. Government. R/V Hugh R. Sharp Funding Information: This study was sponsored by U.S. Department of Energy (DE-FE0028980, awarded to J. D. K; DE-FE0026195 interagency agreement with C. D. R.). We thank the crew of the R/V Hugh R. Sharp for their support, G. Hatcher, J. Borden, and M. Martini of the USGS for assistance with the LADCP, and Zach Bunnell, Lillian Henderson, and Allison Laubach for additional support at sea. The quality of this manuscript was greatly improved thanks to the insightful comments of the two reviewers and P. Hart. Any use of trade, firm or product name is for descriptive purposes only and does not imply endorsement by the U.S. Government. Publisher Copyright: {\textcopyright}2020. American Geophysical Union. All Rights Reserved.",

year = "2021",

month = jan,

doi = "10.1029/2019JG005621",

language = "English",

volume = "126",

journal = "Journal of Geophysical Research G: Biogeosciences",

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publisher = "Wiley-Blackwell Publishing Ltd",

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T1 - Estimating the Impact of Seep Methane Oxidation on Ocean pH and Dissolved Inorganic Radiocarbon Along the U.S. Mid-Atlantic Bight

AU - Garcia-Tigreros, Fenix

AU - Leonte, Mihai

AU - Ruppel, Carolyn D.

AU - Ruiz-Angulo, Angel

AU - Joung, Dong Joo

AU - Young, Benjamin

AU - Kessler, John D.

N1 - Funding Information: This study was sponsored by U.S. Department of Energy (DE‐FE0028980, awarded to J. D. K; DE‐FE0026195 interagency agreement with C. D. R.). We thank the crew of the for their support, G. Hatcher, J. Borden, and M. Martini of the USGS for assistance with the LADCP, and Zach Bunnell, Lillian Henderson, and Allison Laubach for additional support at sea. The quality of this manuscript was greatly improved thanks to the insightful comments of the two reviewers and P. Hart. Any use of trade, firm or product name is for descriptive purposes only and does not imply endorsement by the U.S. Government. R/V Hugh R. Sharp Funding Information: This study was sponsored by U.S. Department of Energy (DE-FE0028980, awarded to J. D. K; DE-FE0026195 interagency agreement with C. D. R.). We thank the crew of the R/V Hugh R. Sharp for their support, G. Hatcher, J. Borden, and M. Martini of the USGS for assistance with the LADCP, and Zach Bunnell, Lillian Henderson, and Allison Laubach for additional support at sea. The quality of this manuscript was greatly improved thanks to the insightful comments of the two reviewers and P. Hart. Any use of trade, firm or product name is for descriptive purposes only and does not imply endorsement by the U.S. Government. Publisher Copyright: ©2020. American Geophysical Union. All Rights Reserved.

PY - 2021/1

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N2 - Ongoing ocean warming can release methane (CH4) currently stored in ocean sediments as free gas and gas hydrates. Once dissolved in ocean waters, this CH4 can be oxidized to carbon dioxide (CO2). While it has been hypothesized that the CO2 produced from aerobic CH4 oxidation could enhance ocean acidification, a previous study conducted in Hudson Canyon shows that CH4 oxidation has a small short-term influence on ocean pH and dissolved inorganic radiocarbon. Here we expand upon that investigation to assess the impact of widespread CH4 seepage on CO2 chemistry and possible accumulation of this carbon injection along 234 km of the U.S. Mid-Atlantic Bight. Consistent with the estimates from Hudson Canyon, we demonstrate that a small fraction of ancient CH4-derived carbon is being assimilated into the dissolved inorganic radiocarbon (mean fraction of 0.5 ± 0.4%). The areas with the highest fractions of ancient carbon coincide with elevated CH4 concentration and active gas seepage. This suggests that aerobic CH4 oxidation has a greater influence on the dissolved inorganic pool in areas where CH4 concentrations are locally elevated, instead of displaying a cumulative effect downcurrent from widespread groupings of CH4 seeps. A first-order approximation of the input rate of ancient-derived dissolved inorganic carbon (DIC) into the waters overlying the northern U.S. Mid-Atlantic Bight further suggests that oxidation of ancient CH4-derived carbon is not negligible on the global scale and could contribute to deepwater acidification over longer time scales.

AB - Ongoing ocean warming can release methane (CH4) currently stored in ocean sediments as free gas and gas hydrates. Once dissolved in ocean waters, this CH4 can be oxidized to carbon dioxide (CO2). While it has been hypothesized that the CO2 produced from aerobic CH4 oxidation could enhance ocean acidification, a previous study conducted in Hudson Canyon shows that CH4 oxidation has a small short-term influence on ocean pH and dissolved inorganic radiocarbon. Here we expand upon that investigation to assess the impact of widespread CH4 seepage on CO2 chemistry and possible accumulation of this carbon injection along 234 km of the U.S. Mid-Atlantic Bight. Consistent with the estimates from Hudson Canyon, we demonstrate that a small fraction of ancient CH4-derived carbon is being assimilated into the dissolved inorganic radiocarbon (mean fraction of 0.5 ± 0.4%). The areas with the highest fractions of ancient carbon coincide with elevated CH4 concentration and active gas seepage. This suggests that aerobic CH4 oxidation has a greater influence on the dissolved inorganic pool in areas where CH4 concentrations are locally elevated, instead of displaying a cumulative effect downcurrent from widespread groupings of CH4 seeps. A first-order approximation of the input rate of ancient-derived dissolved inorganic carbon (DIC) into the waters overlying the northern U.S. Mid-Atlantic Bight further suggests that oxidation of ancient CH4-derived carbon is not negligible on the global scale and could contribute to deepwater acidification over longer time scales.

KW - climate change

KW - DIC

KW - methane

KW - ocean acidification

KW - radiocarbon

KW - U.S Mid-Atlantic Bight

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DO - 10.1029/2019JG005621

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SN - 2169-8953

VL - 126

JO - Journal of Geophysical Research G: Biogeosciences

JF - Journal of Geophysical Research G: Biogeosciences

IS - 1

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ER -

Estimating the Impact of Seep Methane Oxidation on Ocean pH and Dissolved Inorganic Radiocarbon Along the U.S. Mid-Atlantic Bight

Abstract

Bibliographical note

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