Institutional Repository of South China Sea Institute of Oceanology, CAS
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Spatial variations of b-values in the coastal area of Guangdong
No full textWe used earthquake catalogs recorded by Guangdong Seismological Network from 2008 to 2014 to resolve the spatial variations of b-values in the coastal area of Guangdong, particularly in three key research areas (Yangjiang, Heyuan, and offshore Nanao Island) with strong seismicity. Our results revealed that b-values exhibited significant spatial variations, and zones with low b-values could indicate the most likely seismogenic area of large earthquakes. We observed three clear low b-value patches in the offshore Nanao Island. We found a distinct high b-value peak at the depth of 11 km and two minimum peaks at about 14 and 7-8 km in the Yangjiang area. The overall b-values generally decrease with depth in the Heyuan area. The spatial variations of b-values reflect tectonic anomalies; that is, the 'low-high-low' distribution of b-values in the offshore Nanao Island and the Yangjiang area may indicate the anomaly of the crustal structure with a weak layer. The b-values of reservoir-induced seismicity are obviously lower than that induced by tectonism. This finding indicates that the reservoir area is generally at high stress state under the condition of high pore pressure. We inferred that large earthquakes might be prone to occur at 10-12 km depth in the offshore Nanao Island, at 12-15 km depth in the Yangjiang area, and at the lower part of the seismic activity zone in the Heyuan area. Moreover, the upstream area of the Xinfengjiang reservoir is the most likely area of future large earthquakes in the Heyuan area
Microseisms Generated by Super Typhoon Megi in the Western Pacific Ocean
No full textMicroseisms generated by the super typhoon Megi (13-24 October 2010) were detected on both land-based and island-based seismic stations. We applied temporal frequency spectrum analysis to investigate the temporal evolution of the microseisms. When Megi was over the deep basins of the Philippine Sea, only weak microseisms with short-period double frequency (SPDF, similar to 0.20-0.40 Hz) were observed. However, after Megi traveled into the shallower waters of the South China Sea, microseisms with both long-period double frequency (LPDF, similar to 0.12-0.20 Hz) and SPDF were recorded. The excitation source regions of the microseisms were analyzed using seismic waveform records and synthetic modeling in frequency domain. Results reveal that part of the LPDF microseisms were excited in coastal source regions, while the intensity of both LPDF and SPDF microseisms correlated well with the distance from seismic stations to the typhoon center. Synthetic computations of equivalent surface pressure and corresponding microseisms show that the wave-to-wave interaction induced by coastal reflection has primary effects on microseismic frequency band of similar to 0.10-0.20 Hz. The coastal generation of the dispersive LPDF microseisms is also supported by the observation of ocean swells induced by Megi through the images of C-band ENVISAT-ASAR satellite during its migration process. Two source regions of the microseisms during the life span of Megi are finally distinguished: One was mainly located in the left-rear quadrant of the typhoon center that generated both LPDF and SPDF microseisms at shallow seas, while the other one was near the coasts that generated mostly LPDF microseisms
Synthesis of an inorganic-framework molecularly imprinted Fe-doped TiO2 composite and its selective photo-Fenton-like degradation of acid orange II
No full textBACKGROUND: The heterogeneous photo-Fenton-like process is emerging as a promising treatment of dye-containingwastewater because of its economic feasibility and high efficiency. However, it is still required to develop photo-Fenton-like catalysts with highly selective degradation ability and reusability. RESULTS: Inorganic-framework molecularly imprinted Fe-doped TiO2 composites (MIP/Fe-TiO2) were successfully prepared by the sol-gel method, with acid orange II as the template and TiO2 as the matrix material. The photo-Fenton-like catalysts were characterized using FESEM, EDS, BET, X-ray diffraction, FT-IR spectroscopy and UV-vis diffuse reflectance spectroscopy. These methods revealed the well-crystallized anatase phase and good nanometer-level particle sizes. The adsorption property and photo-Fenton-like activity of the catalysts were also studied in single and binary systems, respectively. CONCLUSIONS: Compared with non-imprinted Fe-TiO2 composites (NIP/Fe-TiO2), MIP/Fe-TiO2 showed higher adsorption capacity and selectivity toward the template molecule. In addition, it was found that the molecular recognition ability of MIP/Fe-TiO2 provided the catalysts with rapidly selective photo-Fenton-like degradation of low target pollutant levels (20 mg L-1) in the presence of high levels of interferential pollutant sodium dodecyl benzene sulfonate (100 mg L-1). Moreover, because of the stable physicochemical properties of the inorganic framework, the new photo-Fenton-like catalysts were resistant to photochemical attack and showed favorable reusability. (c) 2017 Society of Chemical Industr
大陆架科学钻探南黄海CSDP-2井的垂直地震剖面资料采集技术
No full textCSDP-2井位于南黄海盆地中部隆起西部,是大陆架科学钻探项目在中部隆起上实施的第一口以探查印支构造面以下海相中-古生界地层属性为目标的科学钻探井,对了解中部隆起前新生代基岩地层赋存关系具有重要意义。为了获取井孔的高精度地层速度及高信噪比地震波场特征,建立准确的地震层位与钻井地层的对应关系,对该井实施了垂直地震剖面(VSP)观测。针对观测井的地震地质条件和观测目标,采用了由4条1500in3的Bolt气枪组成的大容量气枪阵列作为地震激发震源,克服了海相地层顶界面强反射对地震波强烈阻滞的难题;通过三分量数字检波器等间距观测方法,记录传播到井中的地震波场信号。现场的初步处理结果表明,获得了高信噪比的地震波场信号,纵波和转换波信号清晰、特征突出
一份南海深海沉积物样品中可培养细菌的多样性
No full text海洋沉积环境蕴含丰富的微生物资源。对深海难培养微生物的分离培养,不仅有利于深海微生物资源的挖掘与利用,也有利于对深海微生物学的研究。本研究采用多种培养基分离获得细菌菌株纯培养,并通过16S r RNA基因序列鉴定,对我国南海海域1个4 000 m水深的深海表层沉积物样品的可培养细菌多样性进行初探。共设计23种分离培养基,经过选择性分离培养最终获得612株细菌菌株,分别隶属于厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)和拟杆菌门(Bacteroidetes)的9目10科27个属级类群,可培养优势类群为厚壁菌门,占所有分离物种数量的85.8%,包含13个16S rRNA基因序列相似性低于98%的潜在新物种。海洋琼脂类培养基适合培养不同种类的海洋细菌类群,放线菌选择性分离类合成培养基对放线菌类群的分离效果较好。最终获得一些与具有产抗生素、细胞毒素、高效酶活、耐受不良环境、降解污染物等特殊功能微生物相近的菌株。研究结果表明,该深海沉积物样品的可培养微生物资源、潜在新物种和微生物生理特性丰富多样,研究深海环境难培养微生物的分离策略及其微生物适应生理特性对研究极端环境微生物打下了基础
核酸指标对桡足类安氏伪镖水蚤摄食率、生长率及产卵率的指示作用
No full text核酸指标可表征桡足类营养及生长状态,然而多物种和多指标比较研究的相对缺乏却限制了现场海区调查中对核酸标志物的广泛应用。本研究测定了系列饵料浓度(0.2~2.0μg C·m L–1)喂食的安氏伪镖水蚤Pseudodiaptomus annandalei的桡足幼体Ⅱ期个体的摄食率、生长率及成体产卵率,并就生化组成,包括RNA含量、DNA含量、蛋白含量(以下简写为PRO)、RNA∶DNA、RNA∶PRO、DNA∶PRO及元素组成(N含量、P含量、C∶N和C∶P比值)进行定量分析和计算。摄食率、生长率、产卵率及桡足幼体的RNA相关的核酸指标随饵料浓度的变化趋势均符合双曲线模型,而雌性成体中仅RNA∶DNA比值符合此模型。对RNA相关指标与各生理参数的相关性分析显示,桡足幼体的RNA相关指标均与摄食率及生长率呈显著线性相关性,显著程度的顺序为RNA∶DNA>RNA∶PRO>RNA含量;雌性成体中RNA∶DNA及RNA∶PRO比值与产卵率显著相关,前者的相关性远较后者显著。此结果表明,在常用的现场浮游桡足类调查的标志比值(RNA∶DNA比值或RNA含量)之外,RNA∶PRO比值亦可作为指示桡足类生长状态的标志比值,但是当指示体生长时,桡足类必须处于同一生长阶段。RNA相关指标与饵料浓度之间稳固的双曲线相关性提示我们,RNA相关指标可帮助评估桡足类的饵料环境
褐斜鲽(Plagiopsetta glossa)线粒体基因组特征及重排机制研究
No full text冠鲽科(Samaridae)隶属于鲽形目(Pleuronectiformes),包含冠鲽属(Samaris)、沙鲽属(Samariscus)和斜鲽属(Plagiopsetta)。目前研究表明,冠鲽(Samaris cristatus)和满月沙鲽(Samariscus latus)的线粒体基因组结构都有重排,并且两者的基因数量也有差别。为检测斜鲽属鱼类中是否也有不同的特征结构,我们选用褐斜鲽(Plagiopsetta glossa)作为代表种进行斜鲽属鱼类线粒体基因组特征分析,同时与冠鲽属及沙鲽属鱼类的线粒体基因组特征进行对比。分析显示,褐斜鲽的线粒体基因组全长为18723bp,包括39个基因:13个蛋白基因、24个t RNA基因、2个r RNA基因、2个控制区、1个轻链复制起点和比典型基因组多的13个间隔子。和经典鱼类的线粒体基因组相比,褐斜鲽和满月沙鲽都多了t RNA-Cys和t RNA-Tyr两个t RNA,冠鲽只多了t RNA-Cys,且3个种类都多了一个控制区,但褐斜鲽与满月沙鲽的基因排列顺序相同。褐斜鲽线粒体基因的重排导致不同位置的6个t RNA形成了六连体基因簇"t RNA-Cys1-Tyr1-Ser1-Lys-Arg-Ser2","ND5-ND6-Glu-Cytb-Thr"则位于六连体之后,但这11个基因相对的排序没有发生变化。采用双复制随机丢失模型(double replications and random loss,DRRL)对褐斜鲽基因的重排现象进行分析,认为该鱼类基因数量、排列顺序以及比典型基因组多13个间隔子等特征为该模型提供了新的依据
Genome Sequencing of Streptomyces atratus SCSIOZH16 and Activation Production of Nocardamine via Metabolic Engineering
No full textThe Actinomycetes are metabolically flexible microorganisms capable of producing a wide range of interesting compounds, including but by no means limited to, siderophores which have high affinity for ferric iron. In this study, we report the complete genome sequence of marine-derived Streptomyces atratus ZH16 and the activation of an embedded siderophore gene cluster via the application of metabolic engineering methods. The S. atratus ZH16 genome reveals that this strain has the potential to produce 26 categories of natural products (NPs) barring the ilamycins. Our activation studies revealed S. atratus SCSIO ZH16 to be a promising source of the production of nocardamine-type (desferrioxamine) compounds which are important in treating acute iron intoxication and performing ecological remediation. We conclude that metabolic engineering provides a highly effective strategy by which to discover drug-like compounds and new NPs in the genomic era
Angucycline Glycosides from Mangrove-Derived Streptomyces diastaticus subsp SCSIO GJ056
No full textNine new angucycline glycosides designated urdamycins N1-N9 (1-9), together with two known congener urdamycins A (10) and B (11), were obtained from a mangrove-derived Streptomycesdiastaticus subsp. SCSIO GJ056. The structures of new compounds were elucidated on the basis of extensive spectroscopic data analysis. The absolute configurations of 6-9 were assigned by electronic circular dichroism calculation method. Urdamycins N7 (7) and N8 (8) represent the first naturally occurring (5R, 6R)-angucycline glycosides, which are diastereomers of urdamycins N6 (6) and N9 (9), respectively
Modeling the temporal dynamics of intertidal benthic infauna biomass with environmental factors: Impact assessment of land reclamation
No full textAnthropogenic activities such as land reclamation are threatening tidal marshes worldwide. This study's hypothesis is that land reclamation in a semi-enclosed bay alters the seasonal dynamics of intertidal benthic infauna, which is a key component in the tidal marsh ecosystem. Mai Po Tidal Marsh, Deep Bay, Pearl River Estuary, China was used as a case study to evaluate the hypothesis. Ecological models that simulate benthic biomass dynamics with governing environmental factors were developed, and various scenario experiments were conducted to evaluate the impact of reclamations. Environmental variables, selected from the areas of hydrodynamics, meteorology, and water quality based on correlation analysis, were used to generate Bayesian regression models for biomass prediction. The best-performing model, which considered average water age (i.e., a hydrodynamic indicator of estuarine circulation) in the previous month, salinity variation (i.e., standard deviation of salinity), and the total sunny period in the current month, captured well both seasonal and yearly trends in the benthic infauna observations from 2002 to 2008. This model was then used to simulate biomass dynamics with varying inputs of water age and salinity variation from coastal numerical models of different reclamation scenarios. The simulation results suggest that the reclamation in 2007 decreased the spatial and annual average benthic infauna biomass in the tidal marsh by 20%, which agreed with the 28% biomass decrease recorded by field survey. The range of biomass seasonal variation also decreased significantly from 2.1 to 230.5 g/m(2) (without any reclamation) to 1.2 to 131.1 g/m(2) (after the 2007 reclamation), which further demonstrates the substantial ecological impact of reclamation. The ecological model developed in this study could simulate seasonal biomass dynamics and evaluate the ecological impact of reclamation projects. It can therefore be applied to evaluate the ecological impact of coastal engineering projects for tidal marsh management, conservation, and restoration. (c) 2017 Elsevier B.V. All rights reserved