检索结果-南通市图书馆

Sediment Characteristics, Sources, and Transport Patterns in Kompong Som Bay, Cambodia: Indications from Grain Size and Heavy Minerals

引用

Journal of Ocean University of China 2021年第2期20卷 329-339页

作者： LIU Jinqing CHEN Xiaoying YIN Ping CAO Ke GAO Fei MENG Yuanku QIU Jiandong LI Meina College of Earth Science and Engineering Shandong University of Science and TechnologyQingdao 266590China laboratory for marine Mineral resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China key laboratory of marine environmental geology Ministry of Natural ResourcesQingdao Institute of Marine GeologyQingdao 266071China

In this paper, we analyzed the grain size and heavy mineral compositions of 52 surface sediment samples collected from the Kompong Som Bay of Cambodia and the adjacent rivers to depict the marine sedimentary environments and transport processes. Heavy minerals in sediments are dominated by authigenic pyrite, siderite, and tourmaline, with average percentages of 36.52%, 29.02%, and 10.94%, respectively. Two provinces can be divided according to the spatial similarity of minerals. The sediments from Province I, covered by silt grains in the northern bay, are characterized by autogenic pyrite, indicating a weakly reducing environment;whereas in Province II, covered by sand grains in the southern bay, the siderite-tourmaline-authigenic pyrite-zircon-hornblende assemblage occurs, indicating a mild reducing environment and locally oxidizing environment. Most of the sediments in the Kompong Som Bay are introduced from the Preak Piphot River and Srae Ambel River, except that some of them in the south areas come from coastal erosion. Generally, the sediments are difficult to be transported because of the low sediment loads entering the sea and weak hydrodynamic conditions. However, they are transported from the north to the south during the tide ebbing when the hydrodynamic force is much stronger. The sediment distribution and transport patterns are controlled by many factors, including submarine topography, hydrodynamic conditions, the southwest monsoon, land contours, and sediment supply.

关键词： heavy mineral provenance sedimentary environment sediment transport Kompong Som Bay Cambodia

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Seasonal variability of tides in the deep northern South China Sea

引用

Science China Earth Sciences 2019年第4期62卷 671-683页

作者： Jiuqiang ZHAO Yanwei ZHANG Zhifei LIU Yulong ZHAO Meng WANG State key laboratory of marine geology Tongji University

Tides are the major energy source for ocean mixing, regulating the variation of oceanic circulation and sediment transport in the deep sea. Here twenty months of high-resolution current profiles, which were observed via a mooring system at a water depth of 2100 m in the northern South China Sea(SCS), are used to investigate seasonal variability in deep-sea *** analysis shows that tides in this region are dominated by diurnal tide, and both diurnal and semidiurnal tide are vertical mode-1 dominant. Baroclinic diurnal tidal current exhibits pronounced seasonal variability, showing its kinetic energy was the strongest in summer, and the maximum depth-averaged value was up to 86.7 cm^2 s^(-2), which was about 1.5 times of that in winter and twice that in spring and autumn. In contrast, baroclinic semidiurnal tide displays no evident seasonal variability. Such seasonal variability in baroclinic tide was mainly modulated by the barotropic forcing from the Luzon Strait. On the other hand,two anticyclonic eddies and one cyclonic eddy, which originated off southwestern Taiwan in winter, crossed the mooring *** cyclonic eddy had weak impact on current velocity in the deep sea, but the two deep-reaching anticyclonic eddies enhanced the current velocity through the full-water column by inducing strong subinertial flows. Consequently, the kinetic energy of tides was strengthened and the incoherent variance of baroclinic diurnal tide increased in winter, which contributed ～85% of the variability in diurnal tide. Meanwhile, the velocity of baroclinic diurnal tide was reduced in winter, which was attributed to the weakened stratification induced by the passage of anticyclonic eddies in the deep sea. The seasonal variability of tides in the deep northern SCS can provide a dynamic mechanism for interpreting sediment transport processes in the deep sea on different time scales.

关键词： Tides Seasonal variability Subinertial current Mesoscale eddy Deep northern South China Sea

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Quantifying the sources of dissolved inorganic carbon within the sulfate-methane transition zone in nearshore sediments of Qi'ao Island, Pearl River Estuary, Southern China

引用

Science China Earth Sciences 2016年第10期59卷 1959-1970页

作者： WU ZiJun ZHOU HuaiYang REN DeZhang GAO Hang LI JiangTao State key laboratory of marine geology Tongji University

The significance of the various biogeochemical pathways that drive carbon cycling and the relative fractions of dissolved inorganic carbon(DIC) produced by these reactions within the sulfate-methane transition zone(SMTZ) are still being debated. Unraveling these processes is important to our understanding of the benthic DIC sources and their contributions to the global carbon cycle. Here, we measure pore water geochemistry(chlorine, sulfate, methane, Ca^(2+), Mg^(2+), DIC and δ^(13)C-DIC) as well as solid geochemistry(sedimentary organic carbon(SOC) and δ^(13)C of SOC) in nearshore sediments from Qi'ao Island in the Pearl River Estuary of the Southern China Sea. Our analysis indicates that SOC originates from the mixing of carbon from terrestrial and marine sources, and that terrestrial materials dominate the net loss of SOC during the degradation of organic matter, especially at sites located near the river outlets. Sulfate reduction via SOC degradation is not appreciable in the upper sediment layer due to conservative mixing-dilution by freshwater. However, below this layer, the anaerobic oxidation of methane(AOM) and methanogenesis occur. Within the SMTZ, the δ^(13)C mass balance shows that the proportions of DIC derived from organoclastic SO_4^(2-) reduction(OSR) and AOM are 50.3% to 66.7% and 0.1% to 17.9%, respectively, whereas methanogenesis contributes 17.0% to 43.9%. This study reveals that the upward diffusion of DIC from ongoing methanogenesis significantly influences carbon cycling within the SMTZ in these estuarine sediments. As a result, we suggest that the plots of the ratio of change in sulfate to change in DIC in pore water should be used with caution when discriminating between sulfate reduction pathways in methane-rich sediments.

关键词： Dissolved inorganic carbon Sulfate reduction Methane Carbon isotopes Estuaries

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The occurrence phases and enrichment mechanism of rare earth elements in cobalt-rich crusts from Marcus-Wake Seamounts

引用

Acta Oceanologica Sinica 2024年第8期43卷 58-68页

作者： Jingjing Gao Jihua Liu Hui Zhang Shijuan Yan Xiangwen Ren Quanshu Yan key laboratory of marine geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China laboratory for marine geology Laoshan LaboratoryQingdao 266237China

To explore the occurrence phases and enrichment mechanism of rare earth elements(REEs)in cobalt-rich crusts,this study analyzes the mineral composition and REE contents of the samples from Marcus-Wake Seamounts by XRD,ICP-OES and *** results show that,(1)the cobalt-rich crusts contain the major crystalline mineral(vernadite),the secondary minerals(quartz,plagioclase and carbonate fluorapatite),and a large amount of amorphous ferric oxyhydroxides(FeOOH).(2)The cobalt-rich crusts contains higher Mn(10.83%to 28.76%)and Fe(6.14%to 18.86%)relative to other elements,and are enriched in REEs,with total REE contents of 1563−3238μg/g and Ce contents of 790−1722μg/*** earth element contents of the old crusts are higher than those of the new ***,the non-phosphatized crusts have positive Ce and negative Y anomalies,and yet the phosphatized crusts have positive Ce and positive Y anomalies,indicating that cobalt-rich crusts is hydrogenetic and REEs mainly come from seawater.(3)Analytical data also show that the occurrence phases of elements in cobalt-rich crusts are closely related to their mineral *** the non-phosphatized crusts,REEs are adsorbed by colloidal particles into the crusts(about 67%of REEs in the Fe oxide phase,and about 17%of REEs in the Mn oxide phase).In contrast,in the phosphatized crusts(affected by the phosphatization),REEs may combine with phosphate to form rare earth phosphate minerals,and about 64%of REEs are enriched in the residual phase containing carbonate fluorapatite,but correspondingly the influence of Fe and Mn oxide phases on REEs enrichment is greatly *** addition,the oxidizing environment of seawater,high marine productivity,phosphatization,and slow growth rate can promote the REE *** study provides a reference for the metallogenesis of cobalt-rich crusts in the Pacific.

关键词： cobalt-rich crusts REEs occurrence phase enrichment mechanism Marcus-Wake Seamounts

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

An insight into shallow gas hydrates in the Dongsha area,South China Sea

引用

Acta Oceanologica Sinica 2021年第2期40卷 136-146页

作者： Bin Liu Jiangxin Chen Luis MPinheiro Li Yang Shengxuan Liu Yongxian Guan Haibin Song Nengyou Wu Huaning Xu Rui Yang key laboratory of marine Mineral resources Ministry of Natural ResourcesGuangzhou Marine Geological SurveyGuangzhou 510075China key laboratory of Gas Hydrate Ministry of Natural ResourcesQingdao Institute of Marine GeologyQingdao 266071China laboratory for marine Mineral resources Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China Departamento de Geociências and Centre for environmental and marine Studies Universidade de AveiroAveiro 3800Portugal State key laboratory of marine geology Tongji UniversityShanghai 200092China

Previous studies of gas hydrate in the Dongsha area mainly focused on the deep-seated gas hydrates that have a high energy potential,but cared little about the shallow gas hydrates *** gas hydrates have been confirmed by drill cores at three sites(GMGS208,GMGS209 and GMGS216)during the GMGS2 cruise,which occur as veins,blocky nodules or massive layers,at 8–30 m below the *** chimneys and faults observed on the seismic sections are the two main fluid migration *** deep-seated gas hydrate and the shallow hydrate-bearing sediments are two main seals for the migrating *** occurrences of shallow gas hydrates are mainly controlled by the migration of fluid along shallow faults and the presence of deep-seated gas *** gas leakage is taking place at a relatively high-flux state through the vent structures identified on the geophysical data at the seafloor,although without resulting in gas plumes easily detectable by acoustic *** presence of strong reflections on the high-resolution seismic profiles and dim or chaotic layers in the subbottom profiles are most likely good indicators of shallow gas hydrates in the Dongsha *** cold seeps,indicated by either gas plume or seepage vent,can also be used as indicators for neighboring shallow gas hydrates and the gas hydrate system that is highly dynamic in the Dongsha area.

关键词： shallow gas hydrate Dongsha cold seep fluid flow methane-derived authigenic carbonate South China Sea

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Discharge electrode configuration effects on the performance of a plasma sparker

引用

Plasma Science and Technology 2017年第9期19卷 48-55页

作者：裴彦良张连成黄逸凡严辉朱鑫磊刘振闫克平 key laboratory of marine Sedimentology and environmental geology First Institute of OceanographySOA laboratory for marine geology Qingdao National Laboratory for Marine Science and Technology Institute of Industrial Ecology and Environment College of Chemical and Biological EngineeringZhejiang University

A multi-electrode array is commonly applied in a plasma sparker to generate stable acoustic *** this paper, the effects of the electrode configuration on the performance of a plasma sparker have been investigated. In terms of the load electrical characteristics, the electrode radius and distance have negligible influence on the electric characteristics, whereas a larger electrode number results in a smaller voltage and a larger current but has little effect on the load energy. Regarding the acoustic characteristics, both the expansion and collapse pulses can be increased by decreasing the electrode tip radius. the influence of the electrode number and electrode gap distance on the amplitude of the expansion pulse was found to be negligible. And the amplitude of the collapse pulse decreases significantly with increasing electrode number. Increasing the electrode number decreases the energy efficiency for intense bubble interactions, thus, a small electrode tip radius and a small electrode number are preferred for the design of a plasma sparker if the total discharge energy is given.

关键词： negligible collapse bubble radius decreasing preferred neglected initially Figure intense

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The determination of 52 elements in marine geological samples by an inductively coupled plasma optical emission spectrometry and an inductively coupled plasma mass spectrometry with a high-pressure closed digestion method

引用

Acta Oceanologica Sinica 2017年第1期36卷 109-117页

作者： GAO Jingjing LIU Jihua LI Xianguo YAN Quanshu WANG Xiaojing WANG Hongmin key laboratory of marine Chemistry Theory and Technology of Ministry of Education Ocean University of China key laboratory of marine Sedimentary and environmental geology The First Institute of OceanographyState Oceanic Administration laboratory for marine geology Qingdao National Laboratory for Marine Science and Technology

An improved analytical method to determine the content of 52 major, minor and trace elements in marine geological samples, using a HF-HCl-HNO_3 acid system with a high-pressure closed digestion method（HPCD）, is studied by an inductively coupled plasma optical emission spectrometry（ICP-OES） and an inductively coupled plasma mass spectrometry（ICP-MS）. The operating parameters of the instruments are optimized, and the optimal analytical parameters are determined. The influences of optical spectrum and mass spectrum interferences, digestion methods and acid systems on the analytical results are investigated. The optimal spectral lines and isotopes are chosen, and internal standard element of rhodium is selected to compensate for matrix effects and analytical signals drifting. Compared with the methods of an electric heating plate digestion and a microwave digestion, a high-pressure closed digestion method is optimized with less acid, complete digestion,less damage for digestion process. The marine geological samples are dissolved completely by a HF-HCl-HNO_3 system, the relative error（RE） for the analytical results are all less than 6.0%. The method detection limits are 2–40μg/g by the ICP-OES, and 6–80 ng/g by ICP-MS. The methods are used to determine the marine sediment reference materials（GBW07309, GBW07311, GBW07313）, rock reference materials（GBW07103, GBW07104,GBW07105）, and cobalt-rich crust reference materials（GBW07337, GBW07338, GBW07339）, the obtained analytical results are in agreement with the certified values, and both of the relative standard deviation（RSD） and the relative error（RE） are less than 6.0%. The analytical method meets the requirements for determining 52 elements contents of bulk marine geological samples.

关键词： marine geological sample high-pressure closed digestion method inductively coupled plasma optical emission spectrometry inductively coupled plasma mass spectrometry major element minor element trace element

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Organochlorine pesticide and heavy metal residues in some edible biota collected from Quanzhou Bay and Xinghua Bay,Southeast China

引用

Journal of environmental Sciences 2010年第2期22卷 314-320页

作者： Mangala Yatawara Odhiambo Joshua Owago Julia E Burnet key laboratory of Biogeology and environmental geology of Ministry of Education

In order to assess the contamination of edible marine organisms in Quanzhou and Xinghua Bays, Fujian Province, China, concentrations of organochlorine pesticides （hexachlorocyclohexane isomers or HCHs and dichlorodiphenyltrichloroethane isomers/derivatives or DDTs） and heavy metals （Cu, Pb, Zn, As, Cr, Cd, Ni and Hg） in 13 species collected from different sites in the hays were analyzed by GC-ECD and ICP-MS. The concentration of the sum of DDTs exceeded that the sum of HCHs in the samples. Most of the organisms showed higher levels of DDTs than the first level criterion （10 ng/g） for marine biological quality in China （GB 18421-2001） but conformed to the first level criterion （20 ng/g） for HCHs. The estimated mean daily uptake of pesticides was below the level for minimal risk to the consumers. The levels of Cd, As and Pb in most organisms from both bays were markedly elevated and above the recommended legal limits for human consumption. Our results showed the need for routine monitoring of marine species contamination to ensure public and environmental health.

关键词： organochlorine pesticides residue levels technical HCH heavy metals Fujian Province

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Quantitative model evaluation of organic carbon oxidation hypotheses for the Ediacaran Shuram carbon isotopic excursion

引用

Science China Earth Sciences 2017年第12期60卷 2118-2127页

作者： SHI Wei LI Chao Thomas J.ALGEO State key laboratory of Biogeology and environmental geology China University of Geosciences State key laboratory of Geological Processes and Mineral resources China University of Geosciences Department of geology University of Cincinnati

The largest global carbon-cycle perturbation in Earth history was recorded in the Ediacaran—a persistent negative shift in the global marine dissolved inorganic carbon(DIC) reservoir that lasted for ~25–50 million years, with a nadir of –12‰(i.e.,the Shuram Excursion, or SE). This event is considered to have been a result of full or partial oxidation of a large dissolved organic carbon(DOC) reservoir, which, if correct, provides evidence for massive DOC storage in the Ediacaran ocean owing to an intensive microbial carbon pump(MCP). However, this scenario was recently challenged by new hypotheses that relate the SE to oxidization of recycled continentally derived organic carbon or hydrocarbons from marine seeps. In order to test these competing hypotheses,this paper numerically simulates changes in global carbon cycle fluxes and isotopic compositions during the SE, revealing that:(1) given oxygen levels in the Ediacaran atmosphere-ocean of ≤40% PAL, the recycled continental organic carbon hypothesis and the full oxidation of oceanic DOC reservoir hypothesis are challenged by the atmospheric oxygen availability which would have been depleted in 4 and 6 million years, respectively;(2) the marine-seep hydrocarbon oxidation hypothesis is challenged by the exceedingly large hydrocarbon fluxes required to sustain the SE for >25 Myr; and(3) the heterogeneous(partial) DOC oxidation hypothesis is quantitatively able to account for the SE because the total amount of oxidants needed for partial oxidation(<50%)of the global DOC reservoir could have been met.

关键词： Carbon isotope Shuram Excursion Dissolved organic carbon Atmospheric oxygen Oceanic oxidation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Influence of foraminifera on formation and occurrence characteristics of natural gas hydrates in fine-grained sediments from Shenhu area, South China Sea

引用

Science China Earth Sciences 2016年第11期59卷 2223-2230页

作者： LI ChengFeng HU GaoWei ZHANG Wei YE YuGuang LIU ChangLing LI Qing SUN JianYe key laboratory of Gas Hydrate Ministry of Land and Resources Qingdao Institute of Marine Geology laboratory for marine Mineral resources Qingdao National Laboratory for Marine Science and Technology College of Information and Control Engineering China University of Petroleum

marine gas hydrates accumulate primarily in coarse-grained, high-permeability layers; however, highly saturated natural gas hydrates have been discovered in the fine-grained sediments of Shenhu area, South China Sea(SCS). This may be explained by key factors, such as the great abundance of foraminifera shells. In this paper, by analyzing the SCS foraminifera structure and performing hydrate formation experiments in the foraminifera shells, the contribution of foraminifera to hydrate accumulation in the SCS was investigated from a microscopic point of view. Simulations of hydrate formation were carried out in both pure SCS foraminifera shells and the host sediments. Pore structures in typical foraminifera were studied by use of micro-focus X-ray computed tomography(CT) and scanning electron microscopy(SEM). Hydrate growth and occurrence characteristics in the foraminifera shells were observed in-situ. The results showed that the presence of foraminifera significantly enhanced the effective porosity of the SCS sediments. Moreover, while the hydrates grew preferentially in the chambers of the coarse-grained foraminifera by adhering to the inner walls of the foraminifera shells, no apparent hydrate accumulation was observed in the fine-grained or argillaceous matrix. These findings provide a basis for further studies on the accumulation mechanism of hydrates and physical properties of hydrate reservoir in the South China Sea.

关键词： Shenhu area Foraminifera Gas hydrate Occurrence characteristics X-ray computed tomography

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：