scholarly journals The Geology and Biogeochemistry of Hydrocarbon Seeps

2020 ◽  
Vol 48 (1) ◽  
pp. 205-231 ◽  
Author(s):  
Samantha B. Joye
Keyword(s):  
Deep Sea ◽  
Extreme Environments ◽  
Surface Expression ◽  
Oxidation Potential ◽  
Sediment Surface ◽  
Continental Margins ◽  
Anaerobic Oxidation Of Methane ◽  
Oxidation Of Methane ◽  
Hydrocarbon Seeps ◽  
Abundance And Diversity

Hydrocarbon seeps, deep sea extreme environments where deeply sourced fluids discharge at the seabed, occur along continental margins across the globe. Energy-rich reduced substrates, namely hydrocarbons, support accelerated biogeochemical dynamics, creating unique geobiological habitats. Subseafloor geology dictates the surficial expression of seeps, generating hydrocarbon (gas and/or oil) seeps, brine seeps, and mud volcanoes. Biogeochemical processes across the redox spectrum are amplified at hydrocarbon seeps due to the abundance and diversity of reductant; anaerobic metabolism dominates within the sediment column since oxygen is consumed rapidly near the sediment surface. Microbial activity is constrained by electron acceptor availability, with rapid recycling required to support observed rates of hydrocarbon consumption. Geobiologic structures, from gas hydrate to solid asphalt to authigenic minerals, form as a result of hydrocarbon and associated fluid discharge. Animal-microbial associations and symbioses thrive at hydrocarbon seeps, generating diverse and dense deep sea oases that provide nutrition to mobile predators. ▪  Hydrocarbon seeps are abundant deep sea oases that support immense biodiversity and where specialization and adaptation create extraordinary lifestyles. ▪  Subseafloor geology shapes and defines the geochemical nature of fluid seepage and regulates the flux regime, which dictate the surface expression. ▪  High rates of anaerobic oxidation of methane require coupling to multiple processes and promote diversity in the anaerobic methanotroph microbial community. ▪  The recent discovery of novel phyla possessing hydrocarbon oxidation potential signals that aspects of seep biogeochemistry and geobiology remain to be discovered.

scholarly journals Effects of Temperature and Pressure on Sulfate Reduction and Anaerobic Oxidation of Methane in Hydrothermal Sediments of Guaymas Basin

2004 ◽  
Vol 70 (2) ◽  
pp. 1231-1233 ◽  
Author(s):  
Jens Kallmeyer ◽  
Antje Boetius
Keyword(s):  
Sulfate Reduction ◽  
Deep Sea ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Guaymas Basin ◽  
Oxidation Of Methane ◽  
Hydrothermal Sediments ◽  
Deep Sea Sediments ◽  
Effects Of Temperature ◽  
Temperature And Pressure

ABSTRACT Rates of sulfate reduction (SR) and anaerobic oxidation of methane (AOM) in hydrothermal deep-sea sediments from Guaymas Basin were measured at temperatures of 5 to 200°C and pressures of 1 × 105, 2.2 × 107, and 4.5 × 107 Pa. A maximum SR of several micromoles per cubic centimeter per day was found at between 60 and 95°C and 2.2 × 107 and 4.5 × 107 Pa. Maximal AOM was observed at 35 to 90°C but generally accounted for less than 5% of SR.

scholarly journals Phosphorus Species in Deep-Sea Carbonate Deposits: Implications for Phosphorus Cycling in Cold Seep Environments

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 645
Author(s):  
Junlie Zhou ◽  
Mengran Du ◽  
Jiwei Li ◽  
Hengchao Xu ◽  
Kaiwen Ta ◽  
...  
Keyword(s):  
Deep Sea ◽  
Cold Seep ◽  
Anaerobic Oxidation Of Methane ◽  
Cold Seeps ◽  
Organic P ◽  
Anaerobic Oxidation ◽  
Phosphorus Species ◽  
China Sea ◽  
Oxidation Of Methane ◽  
Deep Sediments

Phosphorus (P) is an important nutrient for biological communities in cold seeps. However, our knowledge on the source, species, and cycling of P in cold seep environments is limited. In this study, the concentration, species, and micro to nanometer scale distribution of P in seep carbonates were examined at three deep-sea cold seeps in the South China Sea and East China Sea. The Ca-P accounts for the largest proportion of P—followed by detrital-P, Fe-P, organic-P, and exchangeable-P. The distribution patterns of Ca-P, detrital-P, and organic-P in the seep carbonates differ from one another, as shown by elemental mapping with NanoSIMS and scanning electron microscopy. The covariation of P with Ca and C reveals that Ca-P co-precipitates with Ca-carbonate, which is linked to the process of sulfate-driven anaerobic oxidation of methane. Organic-P is also observed within biofilm-like organic carbon aggregates, revealing the microbial enrichment of P by fluids in the process of anaerobic oxidation of methane. P with a granulated morphology was identified as detrital-P derived from deep sediments. Most importantly, it is evident that Ca-P is positively correlated to the Fe content in all the seep carbonates. This indicates the likelihood that the dissolved P in cold-seep fluids is released primarily from Fe oxides through Fe-driven anaerobic oxidation of methane in deep sediments. These processes associated with different species of P may have significant implications for P geochemical cycling and anaerobic oxidation of methane impelled by Fe and sulfate reduction in cold seep environments.

scholarly journals Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore of Costa Rica

2015 ◽  
Vol 12 (22) ◽  
pp. 6687-6706 ◽  
Author(s):  
P. Steeb ◽  
S. Krause ◽  
P. Linke ◽  
C. Hensen ◽  
A. W. Dale ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Costa Rica ◽  
Sediment Cores ◽  
Methane Flux ◽  
Sediment Surface ◽  
Anaerobic Oxidation Of Methane ◽  
Cold Seeps ◽  
Osa Peninsula ◽  
Oxidation Of Methane

Abstract. Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore of Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane migrating through the sediments of cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at the Quepos Slide site, a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m−2 d−1, with only 1 to 2.5 % of the upward methane flux being released into the water column. Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed sediment-flow-through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within ca. 170 d. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow.

scholarly journals Regulation of anaerobic methane oxidation in sediments of the Black Sea

2008 ◽  
Vol 5 (3) ◽  
pp. 2305-2341 ◽  
Author(s):  
N. J. Knab ◽  
B. A. Cragg ◽  
E. R. C. Hornibrook ◽  
L. Holmkvist ◽  
C. Borowski ◽  
...  
Keyword(s):  
Sulfate Reduction ◽  
Methane Oxidation ◽  
Black Sea ◽  
Deep Sea ◽  
The Black Sea ◽  
Anaerobic Oxidation Of Methane ◽  
Oxidation Of Methane ◽  
History Of ◽  
Carbon Recycling ◽  
Sulfate Reduction Rates

Abstract. Anaerobic oxidation of methane (AOM) and sulfate reduction (SRR) were investigated in sediments of the western Black Sea, where methane transport is controlled by diffusion. To understand the regulation and dynamics of methane production and oxidation in the Black Sea, rates of methanogenesis, AOM, and SRR were determined using radiotracers in combination with pore water chemistry and stable isotopes. On the shelf of the Danube paleo-delta and the Dnjepr Canyon, AOM did not consume methane effectively and upwards diffusing methane created an extended sulfate-methane transition zone (SMTZ) that spread over more than 2.5 m and was located in formerly limnic sediment. Measurable AOM rates occurred mainly in the lower part of the SMTZ, sometimes even at depths where sulfate seemed to be unavailable. The inefficiency of methane oxidation appears to be linked to the limnic history of the sediment, since in all cores methane was completely oxidized at the limnic-marine transition. The upward tailing of methane was less pronounced in a core from the deep sea in the area of the Dnjepr Canyon, the only station with a SMTZ close to the marine deposits. Sulfate reduction rates were mostly extremely low, and in the SMTZ were even lower than AOM rates. Rates of bicarbonate-based methanogenesis were below detection limit in two of the cores, but δ13C values of methane indicate a biogenic origin. The most depleted δ13C-signal was found in the SMTZ of the core from the deep sea, most likely as a result of carbon recycling between AOM and methanogenesis.

scholarly journals Stratified Communities of Active Archaea in Deep Marine Subsurface Sediments

2006 ◽  
Vol 72 (7) ◽  
pp. 4596-4603 ◽  
Author(s):  
Ketil B. Sørensen ◽  
Andreas Teske
Keyword(s):  
16S Rrna ◽  
Sediment Surface ◽  
Anaerobic Oxidation Of Methane ◽  
Rt Pcr ◽  
Ocean Drilling Program ◽  
Clone Libraries ◽  
Oxidation Of Methane ◽  
Geochemical Properties ◽  
Wide Range ◽  
Subsurface Sediments

ABSTRACT Archaeal 16S rRNA was extracted from samples of deep marine subsurface sediments from Peru Margin site 1227, Ocean Drilling Program leg 201. The amounts of archaeal 16S rRNA in each extract were quantified by serial dilution and reverse transcription (RT)-PCR. The results indicated a 1,000-fold variation in rRNA content with depth in the sediment, with the highest concentrations found near the sediment surface and in the sulfate-methane transition zone (SMTZ). The phylogenetic composition of the active archaeal population revealed by cloning and sequencing of RT-PCR products changed with depth. Several phylotypes affiliated with marine benthic group B (MBGB) dominated clone libraries from the upper part of the SMTZ and were detected only in this layer. Members of the miscellaneous crenarchaeotal group (MCG) dominated clone libraries from the other layers. These results demonstrate that archaeal communities change in activity and community composition over short distances in geochemically distinct zones of deep subseafloor sediments and that these changes are traceable in the rRNA pool. It was shown for the first time that members of both the MCG and MBGB Archaea are more active in the SMTZ than in layers above and below. This indicates that they benefit either directly or indirectly from the anaerobic oxidation of methane. They also appear to be ecophysiologically flexible, as they have been retrieved from a wide range of marine sediments of various geochemical properties.

scholarly journals Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore Costa Rica

2014 ◽  
Vol 11 (11) ◽  
pp. 16033-16083
Author(s):  
P. Steeb ◽  
S. Krause ◽  
P. Linke ◽  
C. Hensen ◽  
A. W. Dale ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Costa Rica ◽  
Sediment Cores ◽  
Methane Flux ◽  
Sediment Surface ◽  
Anaerobic Oxidation Of Methane ◽  
Cold Seeps ◽  
Osa Peninsula ◽  
Oxidation Of Methane

Abstract. Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane reaching the seafloor at cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at Quepos Slide site; a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m-2 d-1, with only 1 to 2.5% of the upward methane flux being released into the water column. Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed Sediment-F low-Through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within 150–170 days. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow.

scholarly journals Regulation of anaerobic methane oxidation in sediments of the Black Sea

2009 ◽  
Vol 6 (8) ◽  
pp. 1505-1518 ◽  
Author(s):  
N. J. Knab ◽  
B. A. Cragg ◽  
E. R. C. Hornibrook ◽  
L. Holmkvist ◽  
R. D. Pancost ◽  
...  
Keyword(s):  
Sulfate Reduction ◽  
Methane Oxidation ◽  
Black Sea ◽  
Deep Sea ◽  
The Black Sea ◽  
Anaerobic Oxidation Of Methane ◽  
Oxidation Of Methane ◽  
History Of ◽  
Carbon Recycling ◽  
Sulfate Reduction Rates

Abstract. Anaerobic oxidation of methane (AOM) and sulfate reduction (SRR) were investigated in sediments of the western Black Sea, where upward methane transport is controlled by diffusion. To understand the regulation and dynamics of methane production and oxidation in the Black Sea, rates of methanogenesis, AOM, and SRR were determined using radiotracers in combination with pore water chemistry and stable isotopes. In the Danube Canyon and the Dnjepr palaeo-delta AOM did not consume methane effectively and upwards diffusing methane created an extended sulfate-methane transition zone (SMTZ) that spread over more than 2.5 m and was located in brackish and limnic sediment. Measurable AOM rates occurred mainly in the lower part of the SMTZ, sometimes even at depths where sulfate seemed to be unavailable. The inefficiency of methane oxidation appears to be linked to the paleoceanographic history of the sediment, since in all cores methane was completely oxidized at the transition from the formerly oxic brackish clays to marine anoxic sediments. The upward tailing of methane was less pronounced in a core from the deep sea in the area of the Dnjepr Canyon, the only station with a SMTZ close to the marine deposits. Sub-surface sulfate reduction rates were mostly extremely low, and in the SMTZ were even lower than AOM rates. Rates of bicarbonate-based methanogenesis were below detection limit in two of the cores, but δ13C values of methane indicate a biogenic origin. The most δ13C- depleted isotopic signal of methane was found in the SMTZ of the core from the deep sea, most likely as a result of carbon recycling between AOM and methanogenesis.

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