检索结果-南通市图书馆

Net primary productivity and its control of the Middle Jurassic peatlands: An example from the southern Junggar coalfield

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2018年第11期61卷 1633-1643页

作者： Yanan LI Longyi SHAO Zhiming YAN Haihai HOU Yue TANG David J.LARGE College of geoscience and Surveying Engineering China University of Mining and Technology Oil and Gas Resources Survey center China Geological Survey Administration Faculty of Engineering University of Nottingham

The Jurassic is an important period of global coal formation, including the development of several large coalfields in central Asia and northern China. Individual seams within these peatlands represent sustained periods of terrestrial carbon accumulation and a key environmental indicator attributed to this record is the rate of carbon accumulation. Determining the rate of carbon accumulation requires a measure of time contained within the coal and this study aimed at determining the rate via the identification of Milankovitch orbital cycles using spectral analysis. Spectral analyses of geophysical data from two thick coal seams, No. 43(35.9 m) and No. 3(13.2 m), of the Middle Jurassic of the southern Junggar coalfield were conducted to identify significant signals of variations in ash content. The results showed that the variations in ash content of the coal showed spatial cycles at 0.2, 0.7 and 1.1 m^(-1), which were interpreted to represent 123 ka(eccentricity), 37.1 ka(obliquity), and 21.2 ka(precession) orbital periodicities, respectively. Using this timeframe, the depositional time of the No. 43 and No. 3 coal seams were calculated to be 876–970 and 322–357 ka, respectively. In combination with an understanding of carbon loss during coalification, the carbon accumulation rates of these Middle Jurassic peatlands were calculated to be 58.6–64.9 and60.3–66.8 g C m^(-2) a^(-1) for the No. 43 and No. 3 coal seams, respectively. Given that the net primary productivity(NPP) was 4.3 times the value of the carbon accumulation in a mid-latitude region of 40°–45°N, an NPP of 251.8–279.1 and259.1–287.1 g C m^(-2) a^(-1) was calculated for the No. 43 and No. 3 coal seams, respectively. In the context of the same paleolatitude(40°–45°N) and peat type, the NPP values of the Middle Jurassic strata in the study area were higher than those of the peatlands of the Holocene and Permian, and were similar to the NPP values of Early Cretaceous peatlands. Considering the NPP of a peat

关键词： Peatland Middle Jurassic Milankovitch cycle Net primary productivity Mid-latitude region Paleoclimate

Arsenic distribution and source in groundwater of Yangtze River Delta economic region, China

在线全文

学校读者我要写书评

暂无评论

Journal of Groundwater Science and Engineering 2017年第4期5卷 343-353页

作者： ZHOU Xun School of Environment Studies China University of Geoscience Nanjing center China Geology Survey

This thesis focuses Arsenic(As) distribution and occurrence in groundwater of Yangtze River Delta economic region, East China. 2019 groundwater samples were collected to analyze 26 chemical compositions, including As. The Principal Component Analysis(PCA) was used to find out As source in groundwater. The results show that average As concentration in groundwater of this study is 9.33 μg/l, and maximum As concentration is up to 510 μg/l. The variation coefficient is 314.34%. High arsenic phreatic water(>10 μg/l) distributes along the Yangtze River and its estuary. Weak hydrodynamic conditions, wide p H value variation range and deteriorating environment are dominating factors, especially in Yangtze River Delta. The PCA suggests that arsenic in phreatic water is mainly of natural origin. Part of arsenic may directly originate from sediment organics and be related to organics decomposition.

关键词： Groundwater Arsenic Distribution Source Yangtze River Delta economic region

Genesis of the Nuri Cu-W-Mo Deposit,Tibet,China:Constraints from in situ Trace Elements and Sr Isotopic Analysis of Scheelite

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2024年第1期98卷 117-131页

作者： WANG Yiyun WU Zhishan CHEN Wenqing DU Qing’an TANG Liwei SHI Hongzhao MA Guotao ZHANG Zhi LIANG Wei WU Bo MIAO Hengyi Chengdu center China Geological Survey(Geoscience Innovation Center of Southwest China)Chengdu 610081China The Second Geological Institute of China’s Metallurgical Geology Bureau Fuzhou 351111China

The Nuri deposit is the only Cu-W-Mo polymetallic deposit with large-scale WO3 resources in the eastern section of the Gangdese metallogenic belt,Tibet,***,the genetic type of this deposit has been controversial since its *** on a study of the geological characteristics of the deposit,this study presents mineralization stages,focusing on the oxide stage and the quartz-sulfide stage where scheelite is mainly formed,referred to as Sch-A and Sch-B,*** LA-ICP-MS trace element and Sr isotope analyses,the origin,evolutionary process of the oreforming fluid and genesis of the ore deposit are *** Electron Microscope-Cathodoluminescence(SEMCL)observations reveal that Sch-A consists of three generations,with dark gray homogenous Sch-A1 being replaced by relatively lighter and homogeneous Sch-A2 and Sch-A3,with Sch-A2 displaying a gray CL image color with vague and uneven growth bands and Sch-A3 has a light gray CL image color with hardly any growth *** contrast,Sch-B exhibits a‘core-rim’structure,with the core part(Sch-B1)being dark gray and displaying a uniform growth band,while the rim part(Sch-B2)is light gray and *** normalized distribution pattern of rare earth elements in scheelite and Sr isotope data suggest that the early ore-forming fluid in the Nuri deposit originated from granodiorite porphyry and,later on,some country rock material was mixed in,due to strong water-rock *** the O-H isotope data further indicates that the ore-forming fluid in the Nuri deposit originated from magmatic-hydrothermal sources,with contributions from metamorphic water caused by water-rock interaction during the mineralization process,as well as later meteoric *** intense water-rock interaction likely played a crucial role in the precipitation of scheelite,leading to varying Eu anomalies in different generations of scheelite from the oxide stage to the quartz-sulfide stage,while also causing a

关键词： trace elements in situ Sr isotopes tungsten mineralization Gangdese metallogenic belt Tibet

Application of cathodoluminescence to zircon in FEG-ESEM

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第9期16卷 919-924页

作者： CHEN Li , XU Jun and SU Li (Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China Geology Experimental center, China University of geoscience, Beijing 100083, China) Electron Microscopy Laboratory School of Physics Peking University Beijing 100871 China Geology Experimental center China University of Geoscience Beijing 100083 China

Cathodoluminescence (CL) image analysis of zircon is a key step of mineral micro-area compositional investigation and U-(Th)-Pb dating. We introduce a system consisting of field emission ESEM and high performance cathodoluminescence. This system has obvious advantages in imaging resolution and CL spectrum. We acquired some zircon CL images and spectra to demonstrate the ability of this system. Our results show that this system has a great potential application to characterize and identify the genesis of zircon.

关键词： zircon cathodoluminescence ESEM.

geoscience Frontiers 2013 Annual Convention

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

geoscience Frontiers 2014年第2期5卷 299-301页

作者： Fei Gao Lily Wang Mudan Yin geoscience Frontiers Journal CenterChina University of Geosciences (Beijing)

The 2013 geoscience Frontiers Annual Convention was held in Beijing, China during Nov. 1-2, 2013 hosted by China University of geosciences, Beijing （CUGB）（Fig. 1 ）. This conference assembled earth scientists from 5 countries, including China, India （Dr. C. Manikyamba, Miss Preetha Warrier）, Japan （Prof. T. Tsunogae）, South Korea （Prof. S. Kwon） and South Africa （Prof. H.M. Rajesh）, and also representatives from Elsevier （Beijing） and Thomson Reuters （Beijing） offices.

关键词： Co Man

Electron Magnetohydrodynamics Magnetic Reconnection Experiment on Keda Linear Magnetized Plasma Device

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2019年第1期36卷 40-43页

作者： Feibin Fan Jinlin Xie Qiaofeng Zhang Longlong Sang Weixing Ding CAS Key Laboratory of geoscience Environment School of Earth and Space Sciences University of Science and Technology of China CAS Key Laboratory of geoscience Environment School of Physics University of Science and Technology of China

We conduct an electron magnetohydrodynamics magnetic reconnection experiment with guide-field in our Keda linear magnetized plasma device, in which two pulsed currents with the same direction are conducted in parallel with the axial direction of the main chamber of the device using two long aluminum sticks. After approximately 5μs, an X-type magnetic field line topology is formed at the center of the chamber. With the formation of the X-type topology of magnetic field lines, we can also find the rapid increase of the current and ratio of the common flux to the private flux in this area. Additionally, a reduction in the plasma density and the plasma density concentration along one pair of separatrices can also be found.

关键词： Electron magnetohydrodynamics Magnetic Reconnection Experiment Keda Linear Magnetized Plasma Device

Sedimentary Characteristics of the Second Marine Layer During the Late Marine Isotope Stage 3 in Southern Yellow Sea and Their Response to the East Asian Monsoon

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2018年第5期17卷 1103-1113页

作者： ZHANG Yang LI Guangxue GUO Hongzhou LIU Yong WANG Haoyin XU Jishang DING Dong QIAO Lulu MA Yanyan WANG Liyan LI Qian College of Marine geosciences Ocean University of China Key Laboratory of Submarine geoscience and Prospecting Techniques Ministry of Education Development Research center China Geological Survey

We use the particle size of sediments in core YS01A to study the sedimentary environment of the mud deposit in the central South Yellow Sea of China during late Marine Isotope Stages 3 （MIS3; 40.5 kyr-31.3 kyr）. In addition, the East Asian Monsoon and its relationship with the North Atlantic Ocean climate change are discussed based on the sensitive grain-size calculation and the spectrum analysis. The results show that during late MIS3, the muddy area in the central South Yellow Sea experienced the evolution of coastal facies, shallow marine facies, coastal facies, and continental facies, with weak hydrodynamic conditions. Compared with other climate indicators, we found that there were many century to millennium-scale climate signals documented in the muddy area sediments in the central South Yellow Sea. According to our particle size results, three strong winter monsoon events occurred at 37.6kyr, 35.6kyr and 32.2kyr. The East Asian Winter Monsoon records in core YS01A are consistent with the Greenland ice core and the Hulu cave stalagmite 8180. The millennial and centennial scale cycles, which are 55 yr, 72 yr, 115 yr, 262 yr respectively, correspond to solar activity cycles, while the 1049 yr and 2941 yr cycles correspond to the Dansgaard-Oeschger cycles. These cycles indicate that the paleoclimate evolution of the area was controlled by the solar activities, with the high-latitude driving thermohaline circulation as the main energy conveyor belt, followed by the sea-air-land amplification of the winter monsoon variation in the central Yellow Sea in the late MIS3.

关键词： sedimentary environment central South Yellow Sea East Asian Monsoon sensitive grade calculation thermohaline circulation

Enhanced Degradation of Methyl Parathion in the Ligand Stabilized Soluble Mn(Ⅲ)-Sulfite System

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2019年第4期30卷 861-869页

作者： Caixiang Zhang Xiaoping Liao You Lü Chao Nan State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China Central South China center for geoscience Innovation Wuhan 430074China

The ligand-stabilized soluble Mn(Ⅲ) recognized as active intermediate can potentially mediate the attenuation of contaminants. In this study,the abiotic degradation behaviors of methyl parathion in the ligand stabilized Mn(Ⅲ)-sulfite system were investigated. The results showed that the yield of soluble Mn(Ⅲ) produced from the redox reaction of MnO2 and oxalic acid was dependent linearly on the dosage of Mn O2 and caused the decomposition of methyl parathion up to 50.1% in Mn(Ⅲ)-sulfite system after 30 minutes. The fitted pseudo-first-order reaction constants of methyl parathion degradation increased with the increasing of the amount of produced Mn(Ⅲ) but was not effected linearly by the addition of sulfite. Other ligands,including pyrophosphate and oxalic acid,acted as effective complexing agents to stabilize soluble Mn(Ⅲ),and exhibited competitive effect on methyl parathion degradation with sulfite. The formation of Mn(Ⅲ)-sulfite complexes is the critical step in the system to produce abundant reactive oxygen species identified as SO3·-to facilitate methyl parathion degradation. The hydrolysis and oxidation of methyl parathion were acknowledged as two primary transformation mechanisms in Mn(Ⅲ)-sulfite system. These findings indicate that naturally ligands-stabilized soluble Mn(Ⅲ) can be generated and could oxidatively decompose organophosphate pesticides such as methyl parathion.

关键词： soluble Mn(Ⅲ) sulfite methyl parathion degradation mechanism

A review on the aging phenomena of organic components and their mass transfer through the NAPL interfacial phase

在线全文

学校读者我要写书评

暂无评论

Chinese Journal Of Geochemistry 2013年第3期32卷 252-260页

作者： LIU Lihua Stefan Haderlein Key Laboratory of Renewable Energy and Gas Hydrate Guangzhou Institute of Energy Conversion Chinese Academy of Sciences Eberhard-Karls-University of Tuebingen Center for Applied Geoscience (ZAG)

It occurs worldwide that the organic components of non-aqueous phase liquid (NAPL) enter the porous medium and become the source of contaminants in the subsurface. The transport of the organic components through NAPL interphase into the aqueous phase and the subsurface determines the extent of contamination, the persistence of residual NAPL phases and the techniques of remediation. During the transport process the NAPL interphase may experience "aging", a physical and chemical change when NAPL is exposed to aqueous and or gaseous phases. This aging process alters vice versa the mass transfer behaviour of the organic contaminants in the porous medium.

关键词：老化现象有机组成传质界面相部分和非水相液体评论污染物源