Carbon Geochemistry of Cold Seeps: Methane Fluxes and Transformation in Sediments from Kazan Mud Volcano, Eastern Mediterranean Sea

Despite growing concerns about potential enhancement of global warming and slope failure by methane produced by gas hydrate dissociation, much uncertainty surrounds estimates of gas hydrate reservoir sizes, as well as methane fluxes and oxidation rates at the sea floor. For cold seep sediments of the eastern Mediterranean Sea, depth-dependent methane concentrations and rates of anaerobic oxidation of methane (AOM) are constrained by modeling the measured pore-water sulfate profile. The calculated dissolved methane distribution and flux are sensitive to the advective flow velocity, which is estimated from the depth distributions of conservative pore-water constituents (Na, B). Near-complete anaerobic oxidation of the upward methane flux is supported by the depth distributions of indicative biomarkers, and the carbon isotopic compositions of organic matter and dissolved inorganic carbon. Pore-water and solid-phase data are consistent with a narrow depth interval of AOM, 14-18 cm below the sediment-water interface. Based on an isotopic mass balance, the biomass of the microbial population carrying out oxidation of methane coupled to sulfate reduction at the given methane flux represents about 20% of the total organic carbon, which is a significant pool of in situ formed organic matter. Model results indicate that the asymptotic methane concentration is reached a few meters below the sediment surface. The predicted asymptotic concentration is close to the in situ saturation value with respect to gas hydrate, suggesting that the rate of shallow gas hydrate formation is controlled by the ascending methane flux. The proposed model approach can be used to predict the formation of gas hydrate, and to quantify methane fluxes plus transformation rates in surface sediments where fluid advection is an important transport mechanism.

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Date (Publication)
2003-01-01T00:00:00
Citation identifier
Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/69612

Citation identifier
Digital Object Identifier/http://dx.doi.org/10.1016/S0012-821X(03)00226-7

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Haese, R.R.

 1
Author

Meile, C.

 2
Author

Van Cappellen, P.

 3
Author

de Lange, G.J.

 4
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EGD
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Commonwealth of Australia (Geoscience Australia)
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Commonwealth of Australia (Geoscience Australia)

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  • Geoscientific information

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E
W


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Unknown
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  • External Publication

  • Scientific Journal Paper

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  • model

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  • marine

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  • Earth Sciences

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  • Published_External

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Creative Commons Attribution 4.0 International Licence

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CC-BY

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4.0

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http://creativecommons.org/licenses/

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Australian Government Security ClassificationSystem

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2018-11-01T00:00:00
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https://www.protectivesecurity.gov.au/Pages/default.aspx

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Unclassified
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English
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UTF8

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Commonwealth of Australia (Geoscience Australia)

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Non geographic dataset
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Title

Australian Government Security ClassificationSystem

Edition date
2018-11-01T00:00:00
Website

https://www.protectivesecurity.gov.au/Pages/default.aspx

Classification
Unclassified

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Metadata identifier
urn:uuid/a05f7892-ee2e-7506-e044-00144fdd4fa6

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GeoNetwork UUID

Language
English
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UTF8
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Commonwealth of Australia (Geoscience Australia)

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Non geographic dataset
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nonGeographicDataset

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Geoscience Australia - short identifier for metadata record with

uuid

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eCatId/69612

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https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/metadata/a05f7892-ee2e-7506-e044-00144fdd4fa6

Date info (Revision)
2018-04-22T08:25:46
Date info (Creation)
2009-10-07T00:00:00

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AU/NZS ISO 19115-1:2014

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Title

ISO 19115-1:2014

Metadata standard

Title

ISO 19115-3

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Geoscience Australia Community Metadata Profile of ISO 19115-1:2014

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Version 2.0, September 2018

Citation identifier
https://pid.geoscience.gov.au/dataset/ga/122551

 
 

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Keywords

marine model

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