Anaerobic methane oxidation is an important sink for methane in the ocean's largest oxygen minimum zone

Bo Thamdrup*, Herdís Guðlaug Steinsdóttir, Anthony D. Bertagnolli, Cory Padilla, Nastassia V. Patin, Emilio Garcia-Robledo, Laura A. Bristow, Frank J. Stewart

*Kontaktforfatter for dette arbejde

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

We investigated methane oxidation in the oxygen minimum zone (OMZ) of the eastern tropical North Pacific (ETNP) off central Mexico. Methane concentrations in the anoxic core of the OMZ reached ~ 20 nmol L−1 at off shelf sites and 34 nmol L−1 at a shelf site. Rates of methane oxidation were determined in ship‐board incubations with 3H‐labeled methane at O2 concentrations 0–75 nmol L−1. In vertical profiles at off‐shelf stations, highest rates were found between the secondary nitrite maximum at ~ 130 m and the methane maximum at 300–400 m in the anoxic core. Methane oxidation was inhibited by addition of 1 μmol L−1 oxygen, which, together with the depth distribution, indicated an anaerobic pathway. A coupling to nitrite reduction was further indicated by the inhibitory effect of the nitric oxide scavenger 2‐phenyl‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (PTIO). Metatranscriptomes from the anoxic OMZ core supported the likely involvement of nitrite‐reducing bacteria of the NC10 clade in anaerobic methane oxidation, but also indicated a potential role for nitrate‐reducing euryarchaeotal methane oxidizers (ANME‐2d). Gammaproteobacteria of the Methanococcales were further detected in both 16S rRNA gene amplicons and metatranscriptomes, but the role of these presumed obligately aerobic methane oxidizers in the anoxic OMZ core is unclear. Given available estimates of water residence time, the measured rates and rate constants (up to ~ 1 yr−1) imply that anaerobic methane oxidation is a substantial methane sink in the ETNP OMZ and hence attenuates the emission of methane from this and possibly other OMZs.
OriginalsprogEngelsk
TidsskriftLimnology and Oceanography
ISSN0024-3590
DOI
StatusE-pub ahead of print - 10. jun. 2019

Fingeraftryk

methane
oceans
oxidation
oxygen
ocean
oxidants
nitrites
nitrite
Methanococcales
gamma-Proteobacteria
scavenger
nitric oxide
vertical profile
vertical distribution
residence time
Mexico
incubation
ribosomal RNA
bacterium
rate

Citer dette

@article{19f346a4bfd94201a2f1f07f3fb0af8d,
title = "Anaerobic methane oxidation is an important sink for methane in the ocean's largest oxygen minimum zone",
abstract = "We investigated methane oxidation in the oxygen minimum zone (OMZ) of the eastern tropical North Pacific (ETNP) off central Mexico. Methane concentrations in the anoxic core of the OMZ reached ~ 20 nmol L−1 at off shelf sites and 34 nmol L−1 at a shelf site. Rates of methane oxidation were determined in ship‐board incubations with 3H‐labeled methane at O2 concentrations 0–75 nmol L−1. In vertical profiles at off‐shelf stations, highest rates were found between the secondary nitrite maximum at ~ 130 m and the methane maximum at 300–400 m in the anoxic core. Methane oxidation was inhibited by addition of 1 μmol L−1 oxygen, which, together with the depth distribution, indicated an anaerobic pathway. A coupling to nitrite reduction was further indicated by the inhibitory effect of the nitric oxide scavenger 2‐phenyl‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (PTIO). Metatranscriptomes from the anoxic OMZ core supported the likely involvement of nitrite‐reducing bacteria of the NC10 clade in anaerobic methane oxidation, but also indicated a potential role for nitrate‐reducing euryarchaeotal methane oxidizers (ANME‐2d). Gammaproteobacteria of the Methanococcales were further detected in both 16S rRNA gene amplicons and metatranscriptomes, but the role of these presumed obligately aerobic methane oxidizers in the anoxic OMZ core is unclear. Given available estimates of water residence time, the measured rates and rate constants (up to ~ 1 yr−1) imply that anaerobic methane oxidation is a substantial methane sink in the ETNP OMZ and hence attenuates the emission of methane from this and possibly other OMZs.",
author = "Bo Thamdrup and Steinsd{\'o}ttir, {Herd{\'i}s Gu{\dh}laug} and Bertagnolli, {Anthony D.} and Cory Padilla and Patin, {Nastassia V.} and Emilio Garcia-Robledo and Bristow, {Laura A.} and Stewart, {Frank J.}",
year = "2019",
month = "6",
day = "10",
doi = "10.1002/lno.11235",
language = "English",
journal = "Limnology and Oceanography",
issn = "0024-3590",
publisher = "JohnWiley & Sons, Inc.",

}

Anaerobic methane oxidation is an important sink for methane in the ocean's largest oxygen minimum zone. / Thamdrup, Bo; Steinsdóttir, Herdís Guðlaug; Bertagnolli, Anthony D.; Padilla, Cory; Patin, Nastassia V.; Garcia-Robledo, Emilio; Bristow, Laura A.; Stewart, Frank J.

I: Limnology and Oceanography, 10.06.2019.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Anaerobic methane oxidation is an important sink for methane in the ocean's largest oxygen minimum zone

AU - Thamdrup, Bo

AU - Steinsdóttir, Herdís Guðlaug

AU - Bertagnolli, Anthony D.

AU - Padilla, Cory

AU - Patin, Nastassia V.

AU - Garcia-Robledo, Emilio

AU - Bristow, Laura A.

AU - Stewart, Frank J.

PY - 2019/6/10

Y1 - 2019/6/10

N2 - We investigated methane oxidation in the oxygen minimum zone (OMZ) of the eastern tropical North Pacific (ETNP) off central Mexico. Methane concentrations in the anoxic core of the OMZ reached ~ 20 nmol L−1 at off shelf sites and 34 nmol L−1 at a shelf site. Rates of methane oxidation were determined in ship‐board incubations with 3H‐labeled methane at O2 concentrations 0–75 nmol L−1. In vertical profiles at off‐shelf stations, highest rates were found between the secondary nitrite maximum at ~ 130 m and the methane maximum at 300–400 m in the anoxic core. Methane oxidation was inhibited by addition of 1 μmol L−1 oxygen, which, together with the depth distribution, indicated an anaerobic pathway. A coupling to nitrite reduction was further indicated by the inhibitory effect of the nitric oxide scavenger 2‐phenyl‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (PTIO). Metatranscriptomes from the anoxic OMZ core supported the likely involvement of nitrite‐reducing bacteria of the NC10 clade in anaerobic methane oxidation, but also indicated a potential role for nitrate‐reducing euryarchaeotal methane oxidizers (ANME‐2d). Gammaproteobacteria of the Methanococcales were further detected in both 16S rRNA gene amplicons and metatranscriptomes, but the role of these presumed obligately aerobic methane oxidizers in the anoxic OMZ core is unclear. Given available estimates of water residence time, the measured rates and rate constants (up to ~ 1 yr−1) imply that anaerobic methane oxidation is a substantial methane sink in the ETNP OMZ and hence attenuates the emission of methane from this and possibly other OMZs.

AB - We investigated methane oxidation in the oxygen minimum zone (OMZ) of the eastern tropical North Pacific (ETNP) off central Mexico. Methane concentrations in the anoxic core of the OMZ reached ~ 20 nmol L−1 at off shelf sites and 34 nmol L−1 at a shelf site. Rates of methane oxidation were determined in ship‐board incubations with 3H‐labeled methane at O2 concentrations 0–75 nmol L−1. In vertical profiles at off‐shelf stations, highest rates were found between the secondary nitrite maximum at ~ 130 m and the methane maximum at 300–400 m in the anoxic core. Methane oxidation was inhibited by addition of 1 μmol L−1 oxygen, which, together with the depth distribution, indicated an anaerobic pathway. A coupling to nitrite reduction was further indicated by the inhibitory effect of the nitric oxide scavenger 2‐phenyl‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (PTIO). Metatranscriptomes from the anoxic OMZ core supported the likely involvement of nitrite‐reducing bacteria of the NC10 clade in anaerobic methane oxidation, but also indicated a potential role for nitrate‐reducing euryarchaeotal methane oxidizers (ANME‐2d). Gammaproteobacteria of the Methanococcales were further detected in both 16S rRNA gene amplicons and metatranscriptomes, but the role of these presumed obligately aerobic methane oxidizers in the anoxic OMZ core is unclear. Given available estimates of water residence time, the measured rates and rate constants (up to ~ 1 yr−1) imply that anaerobic methane oxidation is a substantial methane sink in the ETNP OMZ and hence attenuates the emission of methane from this and possibly other OMZs.

U2 - 10.1002/lno.11235

DO - 10.1002/lno.11235

M3 - Journal article

JO - Limnology and Oceanography

JF - Limnology and Oceanography

SN - 0024-3590

ER -