Gas Hydrate System of Shenhu Area, Northern South China Sea: Geochemical Results

Wu, N.; Zhang, Haiqi; Yang, Shengxiong; Zhang, Guangxue; Liang, Jin; Lu, Jin'an; Su, Xinming; Schultheiss, Peter; Holland, Melanie; Zhu, Yefei

doi:10.1155/2011/370298

Cited by 95 publications

(109 citation statements)

References 25 publications

(29 reference statements)

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“…1), including the Pearl River estuary (station A3), coastal and offshore sites close to Hainan Island (E501, E504, and E505, Ͻ200-m water depth) and deep-water sites (Ͼ1,000-m water depth) close to Taiwan Island (CF6), Luzon Island (E407), Dongsha Islands (CF11, CF14, and CF15), Xisha Trough (CF8 and E422), and Xisha Islands (E801). Methane hydrates have previously been discovered in the Shenhu area southwest of Dongsha Islands (46). The Xisha Trough, Jiulong methane reef area southwest of Taiwan Island, and Bijia'nan basin northwest of Luzon Island were previously identified as gas hydrate prospective areas (43)(44)(45).…”

Section: Resultsmentioning

confidence: 99%

“…S1 and S4 in the supplemental material). The nSCS methane hydrates are buried very deeply in the sediments (Ͼ150 m below the seafloor surface), and the nSCS methane seeps are characterized by micro gas venting with conduit/channel diameters of only 200 to 600 m (46,75). The deep burial of methane hydrates and the low level of methane gas venting make the intensity of the methane supply very low and also the methane seeps as localized features in the surface sediments of the nSCS.…”

Section: Discussionmentioning

confidence: 99%

“…Sediment diazotrophic microbiota have not yet been investigated even though they may play an important role in providing newly fixed nitrogen to the oligotrophic SCS ecosystem. In addition, evidenced and prospective methane hydrate reservoirs have been identified in the northern South China Sea (nSCS) (43)(44)(45)(46), and these areas may sustain productive methane-seep-specific ecosystems, requiring a high supply of nitrogenous nutrients and thus favoring the development of an active microbial diazotroph community. The nSCS provides an ideal ecosystem to investigate the distribution and contribution of sediment microbial diazotrophs in general, and the archaeal diazotrophs in particular, to the marine N cycling.…”

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confidence: 99%

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Environment-Dependent Distribution of the Sediment nifH -Harboring Microbiota in the Northern South China Sea

Dang

Yang

et al. 2013

Appl Environ Microbiol

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fThe South China Sea (SCS), the largest marginal sea in the Western Pacific Ocean, is a huge oligotrophic water body with very limited influx of nitrogenous nutrients. This suggests that sediment microbial N 2 fixation plays an important role in the production of bioavailable nitrogen. To test the molecular underpinning of this hypothesis, the diversity, abundance, biogeographical distribution, and community structure of the sediment diazotrophic microbiota were investigated at 12 sampling sites, including estuarine, coastal, offshore, deep-sea, and methane hydrate reservoirs or their prospective areas by targeting nifH and some other functional biomarker genes. Diverse and novel nifH sequences were obtained, significantly extending the evolutionary complexity of extant nifH genes. Statistical analyses indicate that sediment in situ temperature is the most significant environmental factor influencing the abundance, community structure, and spatial distribution of the sediment nifH-harboring microbial assemblages in the northern SCS (nSCS). The significantly positive correlation of the sediment pore water NH 4 ؉ concentration with the nifH gene abundance suggests that the nSCS sediment nifH-harboring microbiota is active in N 2 fixation and NH 4 ؉ production. Several other environmental factors, including sediment pore water PO 4 3؊ concentration, sediment organic carbon, nitrogen and phosphorus levels, etc., are also important in influencing the community structure, spatial distribution, or abundance of the nifH-harboring microbial assemblages. We also confirmed that the nifH genes encoded by archaeal diazotrophs in the ANME-2c subgroup occur exclusively in the deep-sea methane seep areas, providing for the possibility to develop ANME-2c nifH genes as a diagnostic tool for deep-sea methane hydrate reservoir discovery.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Environment-Dependent Distribution of the Sediment nifH -Harboring Microbiota in the Northern South China Sea

Dang

Yang

et al. 2013

Appl Environ Microbiol

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“…South China Sea (passive continental margin) i. Sites SH-2, 23, and 27 [e.g., Matsumoto et al, 2011, and references therein;Wang et al, 2011aWang et al, , 2011bWang et al, , 2014aWang et al, , 2014bWu et al, 2011]. 10.…”

Section: Introductionmentioning

confidence: 99%

Observed correlation between the depth to base and top of gas hydrate occurrence from review of global drilling data

Riedel

Collett

2017

Geochem Geophys Geosyst

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A global inventory of data from gas hydrate drilling expeditions is used to develop relationships between the base of structure I gas hydrate stability, top of gas hydrate occurrence, sulfate‐methane transition depth, pressure (water depth), and geothermal gradients. The motivation of this study is to provide first‐order estimates of the top of gas hydrate occurrence and associated thickness of the gas hydrate occurrence zone for climate‐change scenarios, global carbon budget analyses, or gas hydrate resource assessments. Results from publically available drilling campaigns (21 expeditions and 52 drill sites) off Cascadia, Blake Ridge, India, Korea, South China Sea, Japan, Chile, Peru, Costa Rica, Gulf of Mexico, and Borneo reveal a first‐order linear relationship between the depth to the top and base of gas hydrate occurrence. The reason for these nearly linear relationships is believed to be the strong pressure and temperature dependence of methane solubility in the absence of large difference in thermal gradients between the various sites assessed. In addition, a statistically robust relationship was defined between the thickness of the gas hydrate occurrence zone and the base of gas hydrate stability (in meters below seafloor). The relationship developed is able to predict the depth of the top of gas hydrate occurrence zone using observed depths of the base of gas hydrate stability within less than 50 m at most locations examined in this study. No clear correlation of the depth to the top and base of gas hydrate occurrences with geothermal gradient and sulfate‐methane transition depth was identified.

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“…Dyadin, G. Ginzburg and E. Sloan (USA) claim in their works that gas hydrates reserves (2 × 10 ), their relatively shallow occurrence (under the seabed from the water depth of 300 -500 m), bottom gas hydrates are considered a real alternative to the gas currently produced by conventional methods. Nowadays, the United Kingdom, Germany, Canada, China, the US, Japan and Norway are engaged in the development of gas hydrate extraction technology (Chen et al, 2011;Wu et al, 2011;Yamamoto et.al., 2014).…”

Section: Introductionmentioning

confidence: 99%

Selecting the method of gas hydrate deposits development in terms of the regularities of their formation

Maksymova¹

2018

Min. miner. depos.

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Purpose. To establish and show regularities of gas hydrates fields distribution in the World Ocean for the development of flow diagrams of methane extraction depending on genetic structures and the composition of the host rocks.Methods. The analysis of the existing fields of gas hydrates is made and, in view of impossibility to carry out detailed investigation, an opportunity to develop them is proved, a theoretical approach to a preliminary estimation of mining-and-geological conditions of such fields' excavation is developed. Findings.On the basis of the data obtained in the suggested way, it becomes possible to calculate the necessary technological parameters of processes related to deposits' opening and gas production from the bottom of the World Ocean.Originality. At the present stage of the research into a new alternative and the most promising source of energy, in the total absence of experience in the gas hydrates fields development, great practical significance is attached to the classification of fields by mining-and-geological conditions of their occurrence, as well as to the methodological approach to their development and calculation of technological parameters of methane extraction process from the bottom of the World Ocean with minimum effect onto the Earth's hydrosphere.Practical implications. Types of gas hydrates fields are determined for the first time in terms of mining-and-geological conditions of their development on the basis of genetic origin and structure of the host rocks. A theoretical approach to the description of the processes taking place in the seam during gas hydrates fields development is elaborated.

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Gas Hydrate System of Shenhu Area, Northern South China Sea: Geochemical Results

Cited by 95 publications

References 25 publications

Environment-Dependent Distribution of the Sediment nifH -Harboring Microbiota in the Northern South China Sea

Environment-Dependent Distribution of the Sediment nifH -Harboring Microbiota in the Northern South China Sea

Observed correlation between the depth to base and top of gas hydrate occurrence from review of global drilling data

Selecting the method of gas hydrate deposits development in terms of the regularities of their formation

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