检索结果-南通市图书馆

Acta Oceanologica Sinica 2024年第6期43卷 86-95页

作者： Zhi Yang Jianfang Chen Haiyan Jin Hongliang Li Zhongqiang Ji Yangjie Li Bin Wang Zhenyi Cao Qianna Chen Key Laboratory of Marine Ecosystem Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China

Eutrophication caused by inputs of excess nitrogen(N) has become a serious environmental problem in Hangzhou Bay(China),but the sources of this nitrogen are not well *** this study,the August 2019 distributions of salinity,nutrients [nitrate(NO_(3)^(-)),nitrite,ammonium,and phosphate],and the stable isotopic composition of NO_(3)^(-)(δ^(15)N and δ^(18)O) were used to investigate sources of dissolved inorganic nitrogen(DIN) to Hangzhou B *** distributions of nitrate,salinity,and nitrate δ^(18)O indicate that the Qiantang River,the Changjiang River,and nearshore coastal waters may all contribute nitrate to the *** on the isotopic compositions of nitrate in these potential source waters and conservative mixing of nitrate in our study area,we suggest that the NO_(3)^(- )in Hangzhou B ay was likely derived mainly from soils,synthetic N fertilizer,and manure and ***-member modeling indicates that in the upper half of the bay,the Qiantang River was a very important DIN source,possibly contributing more than 50% of DIN in the bay head *** the lower half of the bay,DIN was sourced mainly from strongly intruding coastal *** coming directly from the Changjiang River made a relatively small contribution to Hangzhou Bay DIN in August 2019.

关键词： nitrogen isotopes oxygen isotopes nitrogen cycle nitrate sources Hangzhou Bay

Strategies towards robust interpretations of in situ zircon oxygen isotopes

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2023年第2期14卷 241-255页

作者： Janne Liebmann Christopher L.Kirkland John B.Cliff Christopher J.Spencer Aaron J.Cavosie Timescales of Mineral Systems Group The Institute for Geoscience Research(TIGeR)School of Earth and Planetary SciencesCurtin UniversityPerthAustralia Pacific Northwest National Laboratory RichlandWashington 99354United States Department of Geological Sciences and Geological Engineering Queen’s UniversityKingstonONCanada Space Science and Technology Centre The Institute for Geoscience Research(TIGeR)School of Earth and Planetary ScienceCurtin UniversityPerthAustralia

oxygen isotopes are a versatile tool to address a wide range of questions in the Earth *** include geothermometry,paleoclimatology,tracing of geochemical reservoirs,fluid-rock interaction,magmatic petrogenesis,and identification of extra-terrestrial *** arguably provides one of the most robust records of primary magmatic O isotope ratio due to low diffusion rates in crystalline *** ability to correlate zircon O isotopes with temporal and petrogenetic information(e.g.U-Pb geochronology,Lu-Hf isotopes,and trace elements)makes this mineral a key archive for understanding Earth’s crustal ***,zircon O isotope geochemistry has found widespread usage to address fundamental questions across the earth and planetary *** general apparent ease of O isotopic acquisition through the advancement of rapid in situ techniques(*** ion mass spectrometry;SIMS)and associated dedicated national laboratories has led to the generation of large O isotopic data sets of variable quality,highlighting the importance of a coherent workflow for data collection,reduction,and *** paper presents a set of approaches for measurement,assessment,and reporting of zircon O isotope *** focus in this contribution is on in situ analysis via secondary ion mass spectrometry using large geometry instruments,but other commonly used techniques are briefly reviewed for *** work aims to provide an analytical framework necessary for geologically meaningful interpretation of O isotope *** addition,we describe inherent geological(***-induced disturbance of the zircon O isotopic system)and analytical(*** due to sample topography effects)challenges and outline means to identify and avoid such issues as a prerequisite to the generation of robust primary O isotopic signatures for geological interpretation.

关键词： In situ oxygen isotopes Zircon SIMS Secondary ion mass spectrometry Off-mount standard

Contribution of crustal materials to the mantle sources of Xiaogulihe ultrapotassic volcanic rocks,Northeast China:New constraints from mineral chemistry and oxygen isotopes of olivine

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

Contribution of crustal materials to the mantle sources of X...

Density-dependent relativistic mean field approach and its application to single-Λhypernuclei in oxygen hyperisotopes

中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： Yang Sun Jifeng Ying Benxun Su Xinhua Zhou Ji'an Shao State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences

Ultrapotassic igneous rocks can generally be divided into two sub-groups based on the tectonic settings in which they *** orogenic sub-group occurs in subduction-related tectonic settings,while the anorogenic subgroup is confined to stable continental *** Pleistocene Xiaogulihe ultrapotassic volcanic rocks outcrop in the western part of Heilongjiang province,northeast China,and are of intraplate origin with respect to its tectonic *** elemental and isotopic investigations have suggested that the mantle source of these volcanic rocks had been modified by continental-derived sediments resulting from an ancient subduction(at least older than 1.5 Ga).In this contribution,we performed in-situ oxygen isotope analysis on olivine grains in these ultrapotassic rocks using secondary ionization mass spectrometry(SIMS).The olivine grains generally have higherδO values and Ca O contents than those of mantle peridotite xenoliths in the nearby Keluo potassic rocks and show linear correlations between major and trace elements,and Fo,suggesting that they are cognate phenocrysts resulted from fractional crystallization *** restricted and non-correlated variations inδO with the Fo of these olivine grains imply that the fractional crystallization processes might have negligible influence on theirδO *** relatively higherδO values of the olivine phenocrysts than the normal mantle imply the addition of anO-rich crustal component into their mantle source after ruling out the crustal contamination of the host *** propose that the high-δO feature of the olivine phenocrysts was inherited from the subducted crustal component in their mantle *** the rapid oxygen isotopic diffusion under high temperature and the long period between mantle metasomatism event and volcanic eruption,it is postulated that the high-δO signature could only be preserved in the relatively cold and stable subcontinental lithospheric *** speculation is co

关键词： Ultrapotassic volcanic rocks oxygen isotopes Crustal materials Olivine

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Physics C 2023年第12期47卷 102-114页

作者：丁士缘杨威孙保元 MOE Frontiers Science Center for Rare isotopes Lanzhou UniversityLanzhou 730000China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China

The in-medium feature of nuclear force, which includes both nucleon-nucleon( NN) and hyperon-nucleon( ΛN) interactions, impacts the description of single-Λ hypernuclei. With the alternated mass number or isospin of hypernuclei, such effects may be unveiled by analyzing the systematic evolution of the bulk and single-particle properties. From a density-dependent meson-nucleon/hyperon coupling perspective, a new ΛN effective interaction in the covariant density functional(CDF) theory, namely, DD-LZ1-Λ1, is obtained by fitting the experimental data ofΛ separation energies for several single-Λ hypernuclei. It is then used to study the structure and transition properties of single-Λ hypernuclei in oxygen hyperisotopes, in comparison with those determined using several selected CDF Lagrangians. A discrepancy is explicitly observed in the isospin evolution of Λ1p spin-orbit splitting with various effective interactions, which is attributed to the divergence of the meson-hyperon coupling strengths with increasing density. In particular, the density-dependent CDFs introduce an extra contribution to reduce the value but enhance the isospin dependence of the splitting, which originates from the rearrangement terms of Λ self-energies. In addition, the characteristics of hypernuclear radii are studied along the isotopic chain. Owing to the impurity effect of theΛ hyperon, a size shrinkage is observed in the matter radii of hypernuclei compared with the cores of normal nuclei,and its magnitude is further elucidated to correlate with the incompressibility of nuclear matter. Moreover, there is a sizable model-dependent trend in which the Λ hyperon radii evolve with neutron number, which is decided partly by the in-medium NN interactions and core polarization effects.

关键词： relativistic mean field theory hypernuclei oxygen isotopes covariant density functional theory

Theoretical Study of Isotopic Effect of oxygen Atom on the Stereodynamics for the O（^3P）＋ D2 → OD ＋ D Reaction

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2010年第12期27卷 46-49页

作者：刘世莉石英 Institute of Atomic and Molecular Physics dilin University Changchun 130012

Quasi-classical trajectory theory is used to study the isotope effect of oxygen atoms on the vector correlations in the O（^3P）＋ D reaction at a collision energy of 25kcal/mol using accurate potential energy surface of the 3A＇ triplet state. The distributions of p（θr） and the distribution of dihedral angel p（φr） as well as p（θr,φr） are calculated. Moreover, four polarization-dependent generalized differential cross sections （PDDCSs） of product are presented in the center-of-mass frame. The results indicate that the polarization of the product presents different characters for the isotope effect of oxygen atoms. Isotopic substitute can cause obviously different effects on the four PDDCSs.

关键词： oxygen isotopes REACTION mechanisms (Chemistry) POTENTIAL energy surfaces DIFFERENTIAL cross sections VECTOR analysis ATOMS

Study on oxygen Isotope Fractionation in RE Oxide Minerals

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

Journal of Rare Earths 1997年第3期15卷 69-72页

作者：方涛裘愉卓 Institute of Geochemistry Academia Sinica Guiyang 550002 China

The oxygen isotope fractionation equations are calculated for major rare earth oxide minerals by using an increment model. The effects of the variation of RE composition, the isomorphic replacement of Ti 4+ , Nb 5+ , Ta 5+ , and Th 4+ and the metamictization on the oxygen isotope fractionation in minerals are also discussed. The rare earth oxides are not applicable for geothermometry due to their changeable oxygen isotope fractionation coefficients.

关键词： Rare earths oxygen isotopes RE oxide minerals Fractionation coefficients

Zircon Xenocrysts from the Shaka Ridge Record Ancient Continental Crust:New U-Pb Geochronological and oxygen Isotopic Data

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2022年第1期33卷 5-16页

作者： Sergey G.Skublov Natalia A.Rumyantseva Qiuli Li Boris G.Vanshtein Dmitriy I.Rezvukhin Xianhua Li Institute of Precambrian Geology and Geochronology of Russian Academy of Sciences St.Petersburg 199034Russia Saint Petersburg Mining University St.Petersburg 199106Russia Institute for Geology and Mineral Resources of the World Ocean(VNIIOkeangeologia) St.Petersburg 190121Russia State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Sobolev Institute of Geology and Mineralogy Siberian Branch of the Russian Academy of SciencesNovosibirsk 630090Russia

Over the past two decades, a significant number of discoveries of ancient zircon xenocrysts in ocean-floor magmatic rocks have been reported. These findings provide compelling evidence for the presence of ancient continental crust within young oceanic lithosphere. Almost all finds of ancient zircon xenocrysts within oceanic crust are from the Mid-Atlantic Ridge. For other localities, however, similar data are very limited. This report presents the first age determinations(U-Pb, SHRIMPII) and isotope-geochemical data(oxygen, trace and rare earth elements) for zircon xenocrysts from gabbro-diorites of the Shaka Ridge, in the vicinity of the Shaka fracture zone, near the western end of the Southwest Indian Ridge. The work is based on a study of bottom rock material dredged during expeditionary research on the R/V"Akademik Fedorov"(Russia) in 2016. The U-Pb isotope system of the zircon xenocrysts recorded a crystallization age of ~2.8 Ga at an upper discordia intercept and an age of ~600 Ma interpreted as the timing of a superimposed thermal event at a lower discordia *** zircon xenocrysts show geochemical signatures of magmatic origin, i.e., fractionated REE distribution spectra with an increase in chondrite-normalized values from light to heavy REE, positive Ce anomalies and negative Eu anomalies, and high Th/U ratios(0.59-7.77). In discrimination diagrams based on a series of inter-element relationships, zircon compositions fall into the fields of zircons from rocks of continental crust, mostly granitoids. The Li content of the zircons is high(1.8 ppm-50 ppm),adding further evidence to their derivation from rocks of continental crust. During their residence within young oceanic crust, the zircon xenocrysts experienced alterations under the influence of submarine high-temperature hydrothermal fluids, which selectively affected the distribution of trace elements in the zircons and reduced the δ;O values to 1.75‰-3.15‰. The presence of obviously older zircons

关键词： zircon U-Pb geochronology oxygen isotopes trace elements rare earth elements Shaka Ridge South Atlantic Southwest Indian Ridge

oxygen isotopic variations in modern cetacean teeth and bones： implications for ecological, paleoecological, and paleoclimatic studies

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2016年第1期61卷 92-104页

作者： Burcu Ciner Yang Wang William Parker Department of Earth Ocean and Atmospheric Scienceand National High Magnetic Field LaboratoryFlorida State UniversityTallahasseeFLUSA Department of Geological Engineering Balikesir UniversityBalikesirTurkey department of earth ocean and atmospheric scienceflorida state universityTallahasseeFLUSA

The oxygen isotope ratios （δ18O） preserved in marine sediments have been widely used to reconstruct past ocean temperatures. However, there remain significant uncertainties associated with this method, owing to assumptions about the δ18O of ancient seawater which affects the temperature inferred from sediment δ18O records. In this study, oxygen isotope compositions of phosphate in teeth and bones from five different modem cetacean species, including sperm whale, pygmy sperm whale, short-finned pilot whale, killer whale, and Cuvier＇s beaked whale, and three fossil whales were determined. The data were used to assess whether the oxygen isotope ratios of biogenic phosphate （δ18Op） from cetaceans are a reliable proxy for the oxygen isotopic composition of ocean water （δ18Ow）. The δ18Op values of modem cetaceans range from 15.5 ‰ to 21.3 ‰, averaging （19.6 ‰ ±0.8 ‰）（n = 136）.Using a greatly expanded global cetacean δ18Op dataset, the following regression equation is derived for cetaceans： δ18Ow = 0.95317 （4-0.03293） δ18Op- 17.971 （＋0.605）, r = 0.97253. The new equation, when applied to fossil teeth and bones, yielded reasonable estimates of ancient seawater δ18Ow values. Intra-tooth isotopic variations were observed within individual teeth. Among the selected species, the killer whale （O. orca） has largest intra-tooth δ18Op preference and migratory the lowest δ18Op values and the variation, reflecting its habitat behavior. The results show that oxygen isotope analysis of phosphate in cetacean teeth and dense ear bones provides a useful tool for reconstructing the oxygen isotopic composition of seawater and for examining environmental preferences （including migratory behavior） of both modem and ancient whales.

关键词： oxygen isotopes Phosphate Cetacean Whales Teeth Bones

Paired Measurements of Foraminiferal δ~ （18） O and Mg/Ca Ratios of Indian Monsoons Reconstructed from Holocene to Last Glacial Record

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2011年第4期85卷 950-956页

作者： Badanal MAHESH Virupaxa BANAKAR George BURR National Institute of Oceanography(CSIR) Dona PaulaGoa 403 004India National Science Foundation-Arizona Accelerator Mass Spectrometer Facility 1118 East 4th StreetTucsonAZ85721-0081USA

The effect of seasonally reversing monsoons in the northern Indian Ocean is to impart significant changes in surface salinity（SS）.Here,we report SS changes during the last 32 kyr in the Lakshadweep Sea（southeastern Arabian Sea）estimated from paired measurements of δ18O and sea surface temperature（SST）using Globigerinoides sacculifer,an upper mixed layer dwelling *** heaviest δ***（-0.07±0.08‰）is recorded between 23 and 15 ka,which could be defined as the last glacial maximum（LGM）.The δ*** between the LGM and Holocene is 2.07‰.The SST shows an overall warming of 2℃from the LGM to Holocene（28℃to 30℃）. However,coldest SSTs are observed prior to LGM,i.e.,～27 *** SS was higher（～38 psu） throughout most of the recorded last glacial period（32.5-15 ka）.This high salinity together with generally lower SSTs suggests a period of sustained weaker summer or stronger winter *** deglacial warming is associated with rapid reorganization of monsoons and is reflected in decreased salinity to a modern level of～36.5 psu,within a period of～5 *** indicates intensification of summer monsoons during cold to warm climate transition.

关键词： paleoclimate oxygen isotopes Mg/Ca thermometry monsoon variability Arabian Sea

Mineralogy, Geochemistry, Fluid Inclusion and oxygen Isotope Investigations of Epithermal Cu±Ag Veins of the Khur Area, Lut Block,Eastern Iran

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2018年第3期92卷 1139-1156页

作者： M.Javidi MOGHADDAM M.H.KARIMPOUR K.Ebrahimi NASRABADI M.R.Haidarian SHAHRI A.Malekzadeh SHAFAROUDI Department of Geology Faculty of Science Ferdowsi University of Mashhad Research Center for Ore Deposit of Eastern Iran Ferdowsi University of Mashhad

The Khur metallogenic district is located in a volcanic-plutonic belt in the central Lut Block(central eastern Iran). Mineralization occurs in Middle Eocene andesitic tuff and along four main vein systems trending northwest-southeast(Shurk, Mir-e-Khash, Shikasteh Sabz and Ghar-e-Kaftar veins).Microscopic studies reveal that the veins contain bornite, chalcocite, pyrite, tennantite together with minor sphalerite and chalcopyrite as hypogene minerals and chalcocite, digenite, covellite, valleriite,malachite, azurite, atacamite, hematite, and goethite as supergene minerals. The ore bodies are accompanied by narrow but intensely developed wall rock alterations of argillization, carbonatization and silicification. Copper content reaches 6.5, 2.4, 4.2 and 5% in Mir-e-Khash, Shikasteh Sabz, Ghar-eKaftar and Shurk, respectively. Microthermometric measurements of quartz-and calcite-hosted fluid inclusions indicate that the mineralization might be derived from a moderately saline hydrothermal fluid at temperatures between 175-316℃. Calculated δO values of water in equilibrium with quartz and calcite for Khur veins suggest that the fluid might have had a magmatic source, but theO-depletion was developed through mixing with meteoric water. Copper deposition in Khur veins is believed to have been largely caused by mixing, although wall rock reactions may also have occurred. The Khur veins are classified as volcanic-subvolcanic hydrothermal-related vein deposits.

关键词： fluid inclusion oxygen isotopes Khur veins Lut Block Iran