Dataset Information

Deep-sea Sediment Resuspension by Internal Solitary Waves in the Northern South China Sea.

ABSTRACT: Internal solitary waves (ISWs) can cause strong vertical and horizontal currents and turbulent mixing in the ocean. These processes affect sediment and pollutant transport, acoustic transmissions and man-made structures in the shallow and deep oceans. Previous studies of the role of ISWs in suspending seafloor sediments and forming marine nepheloid layers were mainly conducted in shallow-water environments. In summer 2017, we observed at least four thick (70-140?m) benthic nepheloid layers (BNLs) at water depths between 956 and 1545?m over continental slopes in the northern South China Sea. We found there was a good correlation between the timing of the ISW packet and variations of the deepwater suspended sediment concentration (SSC). At a depth of 956?m, when the ISW arrived, the near-bottom SSC rapidly increased by two orders of magnitude to 0.62?mg/l at 8?m above the bottom. At two much deeper stations, the ISW-induced horizontal velocity reached 59.6-79.3?cm/s, which was one order of magnitude more than the seafloor contour currents velocity. The SSC, 10?m above the sea floor, rapidly increased to 0.10?mg/l (depth of 1545?m) and 1.25?mg/l (depth of 1252?m). In this study, we found that ISWs could suspend much more sediments on deepwater areas than previously thought. Specifically, we estimated that ISWs could induce and suspend 78.7 Mt/yr of sediment from shelf to deep-sea areas of the northern South China Sea. The total amount of sediment resuspended by shoaling ISWs was 2.7 times that of river-derived sediment reaching the northern South China Sea. This accounted for 6.1% of the global river-discharged sediment (16.4% of that from Asian rivers) transported to the sea.

SUBMITTER: Jia Y

PROVIDER: S-EPMC6702154 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Deep-sea Sediment Resuspension by Internal Solitary Waves in the Northern South China Sea.

Jia Yonggang Y Tian Zhuangcai Z Shi Xuefa X Liu J Paul JP Chen Jiangxin J Liu Xiaolei X Ye Ruijie R Ren Ziyin Z Tian Jiwei J

Scientific reports 20190820 1

Internal solitary waves (ISWs) can cause strong vertical and horizontal currents and turbulent mixing in the ocean. These processes affect sediment and pollutant transport, acoustic transmissions and man-made structures in the shallow and deep oceans. Previous studies of the role of ISWs in suspending seafloor sediments and forming marine nepheloid layers were mainly conducted in shallow-water environments. In summer 2017, we observed at least four thick (70-140 m) benthic nepheloid layers (BNLs ...[more]

PMID: 31431636

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Project description:Metagenomics of marine sediments has uncovered a broad diversity of new uncultured taxa and provided insights into their metabolic capabilities. Here, we detected microbial lineages from a sediment core near the Jiulong methane reef of the northern South China Sea (at 1,100-m depth). Assembly and binning of the metagenomes resulted in 11 genomes (>85% complete) that represented nine distinct phyla, including candidate phyla TA06 and LCP-89, Lokiarchaeota, Heimdallarchaeota, and a newly described globally distributed phylum (B38). The genome of LCP-89 has pathways for nitrate, selenate, and sulfate reduction, suggesting that they may be involved in mediating these important processes. B38 are able to participate in the cycling of hydrogen and selenocompounds. Many of these uncultured microbes may also be capable of autotrophic CO2 fixation, as exemplified by identification of the Wood-Ljungdahl (W-L) pathway. Genes encoding carbohydrate degradation, W-L pathway, Rnf-dependent energy conservation, and Ni/Fe hydrogenases were detected in the transcriptomes of these novel members. Characterization of these new lineages provides insight to the undescribed branches in the tree of life.IMPORTANCE Sedimentary microorganisms in the South China Sea (SCS) remain largely unknown due to the complexity of sediment communities impacted by continent rifting and extension. Distinct geochemical environments may breed special microbial communities including microbes that are still enigmatic. Functional inference of their metabolisms and transcriptional activity provides insight in the ecological roles and substrate-based interactivity of these uncultured Archaea and Bacteria These microorganisms play different roles in utilizing inorganic carbon and scavenging diverse organic compounds involved in the deep-sea carbon cycle. The genomes recovered here contributed undescribed species to the tree of life and laid the foundation for future study on these novel phyla persisting in marginal sediments of the SCS.

Dataset Information

Deep-sea Sediment Resuspension by Internal Solitary Waves in the Northern South China Sea.

Publications

Deep-sea Sediment Resuspension by Internal Solitary Waves in the Northern South China Sea.

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