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  • 1
    Publication Date: 2024-02-02
    Keywords: Batumi Seep; Center for Marine Environmental Sciences; DAPC; DAPC-1; DAPC-12; DAPC-14; DAPC-15; DAPC-16; DAPC-2; DAPC-3; DAPC-8; DAPC-9; Dynamic autoclave piston corer; Elevation of event; Event label; Gas bubble sampler; gas-tight pressure chamber; GBS; GBS-3; GBS-4; GBS-5; GBS-8; GC; GC-13; GC-14; GC-18; GC-23; GC-4; GC-6; GC-8; GeoB11901; GeoB11903; GeoB11904-16; GeoB11906; GeoB11907-2; GeoB11907-5; GeoB11918; GeoB11919; GeoB11920; GeoB11921-1; GeoB11925; GeoB11927; GeoB11936; GeoB11937; GeoB11946; GeoB11949; GeoB11951; GeoB11956; GeoB11958; GeoB11963; GeoB11975; Gravity corer; Latitude of event; Longitude of event; M72/3a; M72/3b; MARUM; Meteor (1986); Pressure; Recovery; Remote operated vehicle; ROV; ROV-8
    Type: Dataset
    Format: text/tab-separated-values, 28 data points
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  • 2
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    PANGAEA
    In:  Supplement to: Pape, Thomas; Bahr, André; Rethemeyer, Janet; Kessler, John D; Sahling, Heiko; Hinrichs, Kai-Uwe; Klapp, Stephan A; Reeburgh, William S; Bohrmann, Gerhard (2010): Molecular and isotopic partitioning of low-molecular-weight hydrocarbons during migration and gas hydrate precipitation in deposits of a high-flux seepage site. Chemical Geology, 269(3-4), 350-363, https://doi.org/10.1016/j.chemgeo.2009.10.009
    Publication Date: 2024-02-02
    Description: Detailed knowledge of the extent of post-genetic modifications affecting shallow submarine hydrocarbons fueled from the deep subsurface is fundamental for evaluating source and reservoir properties. We investigated gases from a submarine high-flux seepage site in the anoxic Eastern Black Sea in order to elucidate molecular and isotopic alterations of low-molecular-weight hydrocarbons (LMWHC) associated with upward migration through the sediment and precipitation of shallow gas hydrates. For this, near-surface sediment pressure cores and free gas venting from the seafloor were collected using autoclave technology at the Batumi seep area at 845 m water depth within the gas hydrate stability zone. Vent gas, gas from pressure core degassing, and from hydrate dissociation were strongly dominated by methane (〉99.85 mol.% of Sum[C1-C4, CO2]). Molecular ratios of LMWHC (C1/[C2 + C3] 〉 1000) and stable isotopic compositions of methane (d13C = -53.5 per mill V-PDB; D/H around -175 per mill SMOW) indicated predominant microbial methane formation. C1/C2+ ratios and stable isotopic compositions of LMWHC distinguished three gas types prevailing in the seepage area. Vent gas discharged into bottom waters was depleted in methane by 〉0.03 mol.% (Sum[C1-C4, CO2]) relative to the other gas types and the virtual lack of 14C-CH4 indicated a negligible input of methane from degradation of fresh organic matter. Of all gas types analyzed, vent gas was least affected by molecular fractionation, thus, its origin from the deep subsurface rather than from decomposing hydrates in near-surface sediments is likely. As a result of the anaerobic oxidation of methane, LMWHC in pressure cores in top sediments included smaller methane fractions [0.03 mol.% Sum(C1-C4, CO2)] than gas released from pressure cores of more deeply buried sediments, where the fraction of methane was maximal due to its preferential incorporation in hydrate lattices. No indications for stable carbon isotopic fractionations of methane during hydrate crystallization from vent gas were found. Enrichments of 14C-CH4 (1.4 pMC) in short cores relative to lower abundances (max. 0.6 pMC) in gas from long cores and gas hydrates substantiates recent methanogenesis utilizing modern organic matter deposited in top sediments of this high-flux hydrocarbon seep area.
    Keywords: Batumi Seep; Center for Marine Environmental Sciences; DAPC; DAPC-1; DAPC-12; DAPC-14; DAPC-15; DAPC-16; DAPC-2; DAPC-3; DAPC-8; DAPC-9; Dynamic autoclave piston corer; Gas bubble sampler; GBS; GBS-3; GBS-4; GBS-5; GBS-8; GC; GC-13; GC-14; GC-18; GC-23; GC-4; GC-6; GC-8; GeoB11901; GeoB11903; GeoB11904-16; GeoB11906; GeoB11907-2; GeoB11907-5; GeoB11918; GeoB11919; GeoB11920; GeoB11921-1; GeoB11925; GeoB11927; GeoB11936; GeoB11937; GeoB11946; GeoB11949; GeoB11951; GeoB11956; GeoB11958; GeoB11963; GeoB11975; Gravity corer; M72/3a; M72/3b; MARUM; Meteor (1986); Remote operated vehicle; ROV; ROV-8
    Type: Dataset
    Format: application/zip, 3 datasets
    Location Call Number Limitation Availability
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  • 3
    Publication Date: 2024-02-02
    Keywords: Batumi Seep; C1/C3 hydrocarbon ratio; C1 hydrocarbons; C2/C3 hydrocarbon ratio; C2 hydrocarbons; C3 hydrocarbons; Carbon dioxide; Center for Marine Environmental Sciences; DAPC; DAPC-1; DAPC-12; DAPC-14; DAPC-15; DAPC-16; DAPC-2; DAPC-3; DAPC-8; DAPC-9; Dynamic autoclave piston corer; Elevation of event; Event label; Gas bubble sampler; Gas dryness; Gas type; GBS; GBS-3; GBS-4; GBS-5; GBS-8; GC; GC-13; GC-14; GC-18; GC-23; GC-4; GC-6; GC-8; GeoB11901; GeoB11903; GeoB11904-16; GeoB11906; GeoB11907-2; GeoB11907-5; GeoB11918; GeoB11919; GeoB11920; GeoB11921-1; GeoB11925; GeoB11927; GeoB11936; GeoB11937; GeoB11946; GeoB11949; GeoB11951; GeoB11956; GeoB11958; GeoB11963; GeoB11975; Gravity corer; iso-C4/n-C4 alkane ratio; iso-C4 hydrocarbons; Latitude of event; Longitude of event; M72/3a; M72/3b; MARUM; Meteor (1986); Methane/C2+ hydrocarbons ratio; n-Propane per total halocarbons; Remote operated vehicle; ROV; ROV-8; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 222 data points
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  • 4
    Publication Date: 2024-02-02
    Keywords: Batumi Seep; Calculated, see reference(s); Center for Marine Environmental Sciences; DAPC; DAPC-1; DAPC-14; DAPC-3; DAPC-8; DAPC-9; Dynamic autoclave piston corer; Elevation of event; Event label; Fractionation factor; Gas bubble sampler; Gas type; GBS; GBS-3; GBS-4; GBS-5; GBS-8; GC; GC-13; GC-14; GC-18; GC-23; GC-4; GC-6; GC-8; GeoB11901; GeoB11904-16; GeoB11906; GeoB11907-2; GeoB11907-5; GeoB11918; GeoB11919; GeoB11920; GeoB11921-1; GeoB11925; GeoB11927; GeoB11936; GeoB11946; GeoB11949; GeoB11951; GeoB11956; GeoB11975; Gravity corer; Latitude of event; Longitude of event; M72/3a; M72/3b; MARUM; Meteor (1986); Remote operated vehicle; ROV; ROV-8; Sample code/label; see reference(s); Δδ13C (C2-C1); Δδ13C (C3-C2); Δδ13C (CO2-C1); δ13C, carbon dioxide, aquatic; δ13C, ethane; δ13C, methane; δ13C, propane; δ13C, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 207 data points
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  • 5
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 17 (2016): 3882–3892, doi:10.1002/2016GC006421.
    Description: Methane seeps were investigated in Hudson Canyon, the largest shelf-break canyon on the northern U.S. Atlantic Margin. The seeps investigated are located at or updip of the nominal limit of methane clathrate hydrate stability. The acoustic identification of bubble streams was used to guide water column sampling in a 32 km2 region within the canyon's thalweg. By incorporating measurements of dissolved methane concentration with methane oxidation rates and current velocity into a steady state box model, the total emission of methane to the water column in this region was estimated to be 12 kmol methane per day (range: 6–24 kmol methane per day). These analyses suggest that the emitted methane is largely retained inside the canyon walls below 300 m water depth, and that it is aerobically oxidized to near completion within the larger extent of Hudson Canyon. Based on estimated methane emissions and measured oxidation rates, the oxidation of this methane to dissolved CO2 is expected to have minimal influences on seawater pH.
    Description: National Science Foundation Grant Number: OCE-1318102; U.S. Department of Energy award Grant Numbers: DE-FE0013999 and NSF OCE-1352301, DOE-USGS, DE-FE0002911 and DE-FE0005806
    Description: 2017-04-13
    Keywords: Methane seeps ; Methane flux ; Methane oxidation ; Hudson Canyon
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America (2012), doi:10.1073/pnas.1110564109.
    Description: Detailed airborne, surface, and subsurface chemical measurements, primarily obtained in May and June 2010, are used to quantify initial hydrocarbon compositions along different transport pathways – in deep subsurface plumes, in the initial surface slick, and in the atmosphere – during the Deepwater Horizon (DWH) oil spill. Atmospheric measurements are consistent with a limited area of surfacing oil, with implications for leaked hydrocarbon mass transport and oil drop size distributions. The chemical data further suggest relatively little variation in leaking hydrocarbon composition over time. While readily soluble hydrocarbons made up ~25% of the leaking mixture by mass, subsurface chemical data show these compounds made up ~69% of the deep plume mass; only ~31% of deep plume mass was initially transported in the form of trapped oil droplets. Mass flows along individual transport pathways are also derived from atmospheric and subsurface chemical data. Subsurface hydrocarbon composition, dissolved oxygen, and dispersant data are used to provide a new assessment of release of hydrocarbons from the leaking well. We use the chemical measurements to estimate that (7.8±1.9) x106 kg of hydrocarbons leaked on June 10, 2010, directly accounting for roughly three-quarters of the total leaked mass on that day. The average environmental release rate of (10.1 ± 2.0) x106 kg/day derived using atmospheric and subsurface chemical data agrees within uncertainties with the official average leak rate of (10.2 ± 1.0) x106 kg/day derived using physical and optical methods.
    Description: This research was supported by the National Science Foundation through grants to D. Blake (AGS-1049952), J. Kessler (OCE-1042650 and OCE-0849246), D. Valentine (OCE-1042097 and OCE-0961725), E. Kujawinski (OCE-1045811), and R. Camilli (OCE-1043976), by U.S. Coast Guard contract to R. Camilli (Contract HSCG3210CR0020), and by U.S. Department of Energy grant to D. Valentine (DE- NT0005667). The August, September, and October research cruises were funded by NOAA through a contract with Consolidated Safety Services, Incorporated. The NOAA P-3 oil spill survey flights were funded in part by NOAA and in part by a U.S. Coast Guard Pollution Removal Funding Authorization to NOAA.
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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  • 7
    Publication Date: 2022-05-25
    Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Reviews of Geophysics 55 (2017): 126–168, doi:10.1002/2016RG000534.
    Description: Gas hydrate, a frozen, naturally-occurring, and highly-concentrated form of methane, sequesters significant carbon in the global system and is stable only over a range of low-temperature and moderate-pressure conditions. Gas hydrate is widespread in the sediments of marine continental margins and permafrost areas, locations where ocean and atmospheric warming may perturb the hydrate stability field and lead to release of the sequestered methane into the overlying sediments and soils. Methane and methane-derived carbon that escape from sediments and soils and reach the atmosphere could exacerbate greenhouse warming. The synergy between warming climate and gas hydrate dissociation feeds a popular perception that global warming could drive catastrophic methane releases from the contemporary gas hydrate reservoir. Appropriate evaluation of the two sides of the climate-methane hydrate synergy requires assessing direct and indirect observational data related to gas hydrate dissociation phenomena and numerical models that track the interaction of gas hydrates/methane with the ocean and/or atmosphere. Methane hydrate is likely undergoing dissociation now on global upper continental slopes and on continental shelves that ring the Arctic Ocean. Many factors—the depth of the gas hydrates in sediments, strong sediment and water column sinks, and the inability of bubbles emitted at the seafloor to deliver methane to the sea-air interface in most cases—mitigate the impact of gas hydrate dissociation on atmospheric greenhouse gas concentrations though. There is no conclusive proof that hydrate-derived methane is reaching the atmosphere now, but more observational data and improved numerical models will better characterize the climate-hydrate synergy in the future.
    Description: U.S. Geological Survey (USGS); USGS and the U.S. Department of Energy Grant Numbers: DE-FE0002911, DE-FE0005806, DE-FE0023495, DE-FE0026195, DE-FE0028980; Department of Earth, Atmospheric and Planetary Sciences; U.S. National Science Foundation, Divisions of Ocean Sciences and Polar Programs Grant Numbers: OCE-0849246 [1300040], 1042650, 1139203, 1318102, PLR-1417149
    Keywords: Methane hydrate ; Climate ; Global warming ; Greenhouse gas
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 8
    Publication Date: 2022-10-31
    Description: Dataset: Radiocarbon in methane at ocean margins
    Description: Water column distribution of radiocarbon (14C) and concentrations of dissolved methane (CH4) collected from US-Atlantic and US-Pacific Margins in 2017 and 2019, respectively. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/861576
    Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1851402, US Department of Energy (DOE) DE-FE0028980
    Keywords: Radiocarbon ; Methane ; Pacific Ocean ; Atlantic Ocean ; Nuclear power
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
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  • 9
    Publication Date: 2022-10-27
    Description: Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(5), (2020): e2019JC015989, doi:10.1029/2019JC015989.
    Description: Relatively minor amounts of methane, a potent greenhouse gas, are currently emitted from the oceans to the atmosphere, but such methane emissions have been hypothesized to increase as oceans warm. Here, we investigate the source, distribution, and fate of methane released from the upper continental slope of the U.S. Mid‐Atlantic Bight, where hundreds of gas seeps have been discovered between the shelf break and ~1,600 m water depth. Using physical, chemical, and isotopic analyses, we identify two main sources of methane in the water column: seafloor gas seeps and in situ aerobic methanogenesis which primarily occurs at 100–200 m depth in the water column. Stable isotopic analyses reveal that water samples collected at all depths were significantly impacted by aerobic methane oxidation, the dominant methane sink in this region, with the average fraction of methane oxidized being 50%. Due to methane oxidation in the deeper water column, below 200 m depth, surface concentrations of methane are influenced more by methane sources found near the surface (0–10 m depth) and in the subsurface (10–200 m depth), rather than seafloor emissions at greater depths.
    Description: This research was supported by DOE Grant (DE‐FE0028980) to J. K. and by DOE‐USGS Interagency Agreement DE‐FE0026195.
    Description: 2020-10-04
    Keywords: Methane ; Ocean ; Isotopes ; Gas seeps ; Mid Atlantic bight ; Oxidation
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 10
    Publication Date: 2022-10-27
    Description: Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Biogeosciences 126(1), (2021): e2019JG005621, https://doi.org/10.1029/2019JG005621.
    Description: 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.
    Description: 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.
    Description: 2021-06-23
    Keywords: Radiocarbon ; Methane ; DIC ; Ocean acidification ; Climate change ; U.S Mid-Atlantic Bight
    Repository Name: Woods Hole Open Access Server
    Type: Article
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