scholarly journals Energy Gradients Structure Microbial Communities Across Sediment Horizons in Deep Marine Sediments of the South China Sea

2018 ◽  
Vol 9 ◽  
Author(s):  
Michael F. Graw ◽  
Grace D'Angelo ◽  
Matthew Borchers ◽  
Andrew R. Thurber ◽  
Joel E. Johnson ◽  
...  
Keyword(s):  
South China Sea ◽  
Microbial Communities ◽  
Marine Sediments ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
China Sea

Seasonal and spatial diversity of microbial communities in marine sediments of the South China Sea

2011 ◽  
Vol 100 (3) ◽  
pp. 317-331 ◽  
Author(s):  
Jikun Du ◽  
Kai Xiao ◽  
Yali Huang ◽  
Huixian Li ◽  
Hongming Tan ◽  
...  
Keyword(s):  
South China Sea ◽  
Microbial Communities ◽  
Marine Sediments ◽  
South China ◽  
Spatial Diversity ◽  
The South China Sea ◽  
The South ◽  
China Sea

scholarly journals Strength Behaviors of Remolded Hydrate-Bearing Marine Sediments in Different Drilling Depths of the South China Sea

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 253 ◽  
Author(s):  
Yanghui Li ◽  
Tingting Luo ◽  
Xiang Sun ◽  
Weiguo Liu ◽  
Qingping Li ◽  
...  
Keyword(s):  
South China Sea ◽  
Marine Sediments ◽  
South China ◽  
The South China Sea ◽  
Triaxial Tests ◽  
Failure Strength ◽  
The South ◽  
Drilling Depth ◽  
China Sea ◽  
Hydrate Reservoirs

The mechanical behaviors of hydrate-bearing marine sediments (HBMS) drilled from the seafloor need to be understood in order to safely exploit natural gas from marine hydrate reservoirs. In this study, hydrates were prepared using ice powder and CH4 gas, and HBMS from the Shenhu area in the South China Sea were remolded using a mixed sample preparation method. A series of triaxial tests were conducted on the remolded HBMS to investigate the effects of soil particle gradation and the existence of hydrate on the mechanical properties of hydrate reservoirs. The results show that the stiffness and failure strength of HBMS decrease along with the decrease of mean particle size and soil aggregate morphology change at different drilling depths, and the reduction of failure strength is more than 20% when the drilling depth drops by 30 m. A better particle gradation of marine sediments may boost the stiffness and failure strength of HBMS. In addition, the existence of hydrate plays an important role in the strength behaviors of HBMS. The reduction of failure strength of HBMS with 30% initial hydrate saturation is more than 35% after complete hydrate dissociation.

scholarly journals Petrographical and Geochemical Signatures Linked to Fe/Mn Reduction in Subsurface Marine Sediments from the Hydrate-Bearing Area, Dongsha, the South China Sea

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 624 ◽  
Author(s):  
Xi Xiao ◽  
Qian-Zhi Zhou ◽  
Shao-Ying Fu ◽  
Qian-Yong Liang ◽  
Xiang-Po Xu ◽  
...  
Keyword(s):  
Organic Matter ◽  
South China Sea ◽  
Marine Sediments ◽  
South China ◽  
Inorganic Carbon ◽  
Solid Phase ◽  
The South China Sea ◽  
Anaerobic Oxidation Of Methane ◽  
The South ◽  
China Sea

Fe and Mn oxides and (oxy)-hydroxides are the most abundant solid-phase electron acceptors in marine sediments, and dissimilatory Fe/Mn reduction usually links with the anaerobic oxidation of methane (AOM) and organic matter oxidation (OMO) in sediments. In this study, we report the results from subsurface marine sediments in the Dongsha hydrate-bearing area in the South China Sea. The petrological and geochemical signatures show that the Fe/Mn reduction mediated by AOM and OMO might occur in sediments above the sulfate-methane transition zone. X-ray diffraction and scanning electron microscopy analyses of sediments indicate that Fe(III)/Mn(IV)-oxides and authigenic carbonate minerals coexisted in the Fe/Mn reduction zone. The lower δ13C values of dissolved inorganic carbon, coupled with an evident increase in total inorganic carbon contents and a decrease in Ca2+ and Mg2+ concentrations indicate the onset of AOM in this zone, and the greater variation of PO43− and NH4+ concentrations in pore water suggests the higher OMO rates in subsurface sediments. Geochemical and mineralogical analyses suggest that the previously buried Fe(III)/Mn(IV) oxides might be activated and lead to the onset of Fe/Mn reduction induced by AOM and OMO. These findings may extend our understanding of the biogeochemical processes involved in Fe/Mn reduction in continental shelves with abundant methane, organic matter, and terrigenous metal oxides.

Strength and Deformation Behaviors of Methane Hydrate-Bearing Marine Sediments in the South China Sea during Depressurization

2021 ◽  
Vol 35 (18) ◽  
pp. 14569-14579
Author(s):  
Tingting Luo ◽  
Tao Han ◽  
Madhusudhan B N ◽  
Xiaodong Zhao ◽  
Di Zou ◽  
...  
Keyword(s):  
South China Sea ◽  
Marine Sediments ◽  
South China ◽  
Methane Hydrate ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Deformation Behaviors ◽  
Strength And Deformation

Modern pollen distribution in marine sediments from the northern part of the South China Sea

2014 ◽  
Vol 108 ◽  
pp. 41-56 ◽  
Author(s):  
Chuanxiu Luo ◽  
Muhong Chen ◽  
Rong Xiang ◽  
Jianguo Liu ◽  
Lanlan Zhang ◽  
...  
Keyword(s):  
South China Sea ◽  
Marine Sediments ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Modern Pollen ◽  
Pollen Distribution

scholarly journals Characterization of particle-associated and free-living bacterial and archaeal communities along the water columns of the South China Sea

2020 ◽  
Author(s):  
Jiangtao Li ◽  
Lingyuan Gu ◽  
Shijie Bai ◽  
Jie Wang ◽  
Lei Su ◽  
...  
Keyword(s):  
South China Sea ◽  
Microbial Communities ◽  
South China ◽  
Deep Ocean ◽  
Archaeal Community ◽  
The South China Sea ◽  
The South ◽  
Free Living ◽  
China Sea ◽  
Archaeal Communities

Abstract. There is a growing recognition of the role of particle-attached (PA) and free-living (FL) microorganisms in marine carbon cycle. However, current understanding of PA and FL microbial communities is largely on those in the upper photic zone, and relatively fewer studies have focused on microbial communities of the deep ocean. Moreover, archaeal populations receive even less attention. In this study, we determined bacterial and archaeal community structures of both the PA and FL assemblages at different depths, from the surface to the bathypelagic zone along two water column profiles in the South China Sea. Our results suggest that environmental parameters including depth, seawater age, salinity, POC, DOC, DO and silicate play a role in structuring these microbial communities. Generally, the PA microbial communities have relatively low abundance and diversity compared with the FL microbial communities at most depths. Further microbial community analysis revealed that PA and FL fractions generally accommodate significantly divergent microbial compositions at each depth. The PA bacterial communities mainly comprise members of Actinobacteria and γ-Proteobacteria, together with some from Bacteroidetes, Planctomycetes and δ-Proteobacteria, while the FL bacterial lineages are mostly distributed within α-, γ-Proteobacteria, Actinobacteria and Bacteroidetes, along with certain members from β-, δ-Proteobacteria, Planctomycetes and Firmicutes. Moreover, there is an obvious shifting in the dominant PA and FL bacterial compositions along the depth profiles from the surface to the bathypelagic deep. By contrast, both PA and FL archaeal communities dominantly consist of Marine Group II (MGII) and Marine Group I (MGI), together with variable minor Marine Group III (MGIII), Methanosarcinales, Marine Benthic Group A (MBG-A) and Woesearchaeota. However, the pronounced distinction of archaeal community compositions between PA and FL fractions are observed at finer taxonomic level. A high proportion overlap of microbial compositions between PA and FL fractions implies that most microorganisms are potentially generalists with PA and FL dual lifestyle for versatile metabolic flexibility. In addition, microbial distribution along the depth profile indicates a potential vertical connectivity between the surface-specific microbial lineages and those in the deep ocean, likely through microbial attachment to sinking particles.

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