Oxygen isotope zoning in garnet

Oxygen isotope zoning was examined within garnet with the use of the stable isotope laser probe. Four metamorphic garnets from the regional metamorphic terrane in Vermont and the skarn deposit at Carr Fork, Utah, were examined and were found to be concentrically zoned in delta(18)O values. The largest variations in delta(18)O values were observed in the regional metamorphic garnets, where delta(18)O values change by 3 per mil from core to rim. These oxygen isotope zoning profiles reflect the changes in the delta(18)O values of the rocks during garnet growth, which are caused by infiltration of fluids and by dehydration reactions during metamorphism.     

棉花吸收稀土元素的动态研究

以鲁棉６号及棕壤、褐土、潮土和砂姜黑土为试验材料，进行棉花自然吸收稀土的动态研究。结果表明，在棉花生长发育的早中期，叶中的稀土含量和吸收量均高于茎和根。在成熟期根中的稀土含量和吸收量均达最高值。叶和茎的稀土含量在不同的生育期中变化较平缓，而根的稀上含量变幅较大，呈前高中低后又高的变化趋势。稀土在棉花发育的花龄期有较强的活力，提示我们施用稀土应在生长的早期。土壤的稀土含量状况和其他农化性状也影响着棉花对稀土的吸收。与棉花叶片稀土含量的临界值相比较，４种土壤均需要施用稀土元素肥料。     

山西土壤稀土元素背景值

在山西省内根据主要土壤类型布设典型剖面１５个，分层采集土壤样品，测试分析其中稀土元素的含量。经统计分析，获得了山西省土壤中１５个稀土元素背景值。与中国土壤和世界土壤稀土元素背景值比较，均无显著性差异，且均在世界土壤稀土元素含量范围之内。     

Ultradeep (greater than 300 kilometers), ultramafic upper mantle xenoliths

Geophysical discontinuities in Earth's upper mantle and experimental data predict the structural transformation of pyroxene to garnet and the solid-state dissolution of pyroxene into garnet with increasing depth. These predictions are indirectly verified by omphacitic pyroxene exsolution in pyropic garnet-bearing xenoliths from a diamondiferous kimberlite. Conditions for silicon in octahedral sites in the original garnets are met at pressures greater than 130 kilobars, placing the origin of these xenoliths at depths of 300 to 400 kilometers. These ultradeep xenoliths support the theory that the 400-km seismic discontinuity is marked by a transition from peridotite to eclogite.     

Precision Lattice-Parameter Determination of (Mg,Fe)SiO3 Tetragonal Garnets

The tetragonal garnet (Mg,Fe)SiO(3) is a high-pressure phase of pyroxene that is thought to be a major constituent of the earth's upper mantle. Its crystal structure is similar to that of cubic garnet, but it is slightly distorted to tetragonal symmetry so that its x-ray powder diffraction pattern shows a very small line splitting. A suite of tetragonal garnets with different compositions in the MgSiO(3)-rich portion of the MgSiO(3)-FeSiO(3) system was synthesized at about 20 gigapascals and 2000 degrees C. The lattice parameters a and c of quenched samples were determined by whole-powder-pattern decomposition analysis of Fe Kalpha x-ray powder diffraction data, which has the capacity to resolve to a high degree heavily overlapping reflections. It was found that the lattice parameters can be obtained from the following equations; a (in angstroms) = 11.516 + 0.088x and c (in angstroms) = 11.428 + 0.157x, where x, teh mole fraction of FeSiO(3), is 0.0 相似文献   

影响脐橙品质的稀土主成分分析

通过对影响脐橙品质的稀土进行主成分分析,结果表明,脐橙品质与稀土元素均有密切的关系(主成分分析贡献率达到74.9%),其中与轻稀土元素、Y元素有着更密切的关系。脐橙种植过程中,应全面施用稀土微肥,在所有稀土元素不可缺少的前提下,增加轻稀土元素与Y元素的含量比例,更有利于促进脐橙的生长与品质的提高。     

History and Present Situation and Developing Tendency of Rare Earth Applied in Agriculture

History of rare earth applied in agriculture Concept of rare earth Rare earth(RE for short)is a general designation of 17 elements,including 15 elements of lanthanum system,they are lanthanum (La),cerium (Ce),praseodymium (Pr),neodymium (Nd),promethium(Pm),samarium(Sm),europium(Eu),gadolinium(Gd),terbium(Tb),dysprosium(Dy),holmium(Ho),erbium(Er),thulium(Tm),ytterbium(Yb),lutetium(Lu)),and 2 elements of the same clan with lanthanum system: scandium (Se)and yttrium (Y) in the periodic table of elements.Rare earth look like earth or soil,and their quantity which may be separated from ore are very rare or few,so scientists call them rare earth elements.     

氨态氮肥和尿素中稀土元素含量比较

[目的]探讨肥料形态对土壤中稀土元素含量的影响。[方法]利用ICP-MS分析硫酸铵和尿素两种氮肥中稀土元素的含量,研究施用不同形态肥料对土壤中稀土元素含量的影响。[结果]硫酸铵中La、Ce、Pr、Nd含量均高于尿素,La、Pr和Nd含量分别是尿素的6.7、9.9和12.8倍。硫酸铵中纯氮含量不到尿素的50%,使用氮肥时铵态氮肥施用量高于尿素。在同时施肥情况下,硫酸铵施入土壤后的稀土元素La、Pr和Nd分别是尿素施入土壤后的13.4、19.8和25.6倍。[结论]铵态氮肥(硫酸铵)的稀土元素含量是尿素的数倍,有利于补充土壤中的稀土元素。     

稀土元素对黄粉虫幼虫的生理影响

在室温条件下用含不同稀土剂量的饲料喂养黄粉虫,发现在每kg饲料中添加100mg氧化镧可使黄粉虫幼虫的一些重要生理指标发生明显的变化:幼虫的生长速度显著加快,幼虫的存活率有所提高.     

稀土对黄秋葵光合生理特性的影响

以黄秋葵的两个品种‘碧剑’和‘纤指’为材料,研究了稀土对其光合生理特性的影响。结果表明：施用稀土可提高两品种幼苗叶片的可溶性蛋白和叶绿素含量,有效提高了两品种的光合效率。     

福建省几种典型红壤性水稻土稀土含量的研究——Ⅱ.稀土与土壤成分的相关分析

对供试土壤的稀土总量(Σ REE),轻稀土含量(Σ LREE)和重稀土含量(Σ HREE)与土壤颗粒组成、有机质含量、腐殖质组成及不同形态氧化铁含量之间的相关关系进行了统计分析.结果表明:(1)ΣREE、Σ LREE 与土壤粘粒,有机质、腐殖质及组成,Fe_t,Fe_d,Fe_(d_o),Fe_(t-d)之间均呈极显著相关;(2)Σ HREE 与上述物质的相关均不显著.     

福建省武夷山地区土壤与武夷岩茶中稀土元素的研究

通过福建省武夷山地区的茶园土壤样品与及生长的茶叶样品的采集,采用ICP-MS对茶叶与土壤样品进行16种稀土元素含量的分析,对茶叶与土壤稀土元素进行统计分析,结果表明:武夷山地区武夷岩茶对土壤中的稀土元素Ce、La有富集作用,与茶叶稀土含量具有正相关性,而茶叶对土壤稀土元素Sc的吸收率为0.5%～5.0%,与Ce、La的吸收率相比较,处于低水平的吸收富集。     

Hotspots, basalts, and the evolution of the mantle

The trace element concentration patterns of continental and ocean island basalts and of mid-ocean ridge basalts are complementary. The relative sizes of the source regions for these fundamentally different basalt types can be estimated from the trace element enrichment-depletion patterns. Their combined volume occupies most of the mantle above the 670 kilometer discontinuity. The source regions separated as a result of early mantle differentiation and crystal fractionation from the resulting melt. The mid-ocean ridge basalts source evolved from an eclogite cumulate that lost its late-stage enriched fluids at various times to the shallower mantle and continental crust. The mid-ocean ridge basalts source is rich in garnet and clinopyroxene, whereas the continental and ocean island basalt source is a garnet peridotite that has experienced secondary enrichment. These relationships are consistent with the evolution of a terrestrial magma ocean.     

稀土微肥在金针菇上的应用

介绍了使用不同浓度的稀土微肥拌料按常规栽培金针菇的试验,结果表明:农用硝酸稀土浓度为50 mg/kg时,促进菌丝生长、出菇整齐,产量较对照提高26.1%.用50 mg/kg稀土微肥处理过的金针菇,菌盖小,菌柄长而粗,菌柄基部呈淡黄色至褐色,经济性状优于对照.     

The Tunguska Explosion of 1908: Discovery of Meteoritic Debris near the Explosion Site and at the South Pole

Submillimeter-sized metallic spheres extracted from soil in the Tunguska region of central Siberia contain noble metals in cosmic proportions. The trace element composition and geographical distribution of these spheres suggest that they are from the 30 June 1908 Tunguska explosion and not meteoritic ablation products falling continuously on the earth. Debris from this explosion was also discovered in a South Pole ice core; this discovery indicates that the Tunguska object exploded in the atmosphere with subsequent stratospheric injection and transport of the debris. The celestial body that exploded over Tunguska weighed more than 7 million tons, was more than 0.16 kilometer in diameter, and may well have been a stony meteorite. This discovery offers a new precision time marker in polar ice strata for the year 1909. The steady-state influx of cosmic matter at the South Pole is estimated to be 1.8 x 10(-8) grams per square centimeter per year, which corresponds to a global influx of 4 x l0(5) tons per year.     

稀土元素对黄粉虫成虫的生理影响

在室温条件下用含不同稀土剂量的饲料喂养黄粉虫,发现在每kg饲料中添加100mg氧化镧可使黄粉虫成虫的一些重要的生理指标发生明显的变化:成虫的存活率显著提高,雌虫提前2d产卵,雌虫的产卵期缩短了5d,雌虫的产卵量显著提高.     

Mantle oxidation state and its relationship to tectonic environment and fluid speciation

The earth's mantle is degassed along mid-ocean ridges, while rehydration and possibly recarbonaton occurs at subduction zones. These processes and the speciation of C-H-O fluids in the mantle are related to the oxidation state of mantle peridotite. Peridotite xenoliths from continental localities exhibit an oxygen fugacity (fo(2)) range from -1.5 to +1.5 log units relative to the FMQ (fayalite-magnetite-quartz) buffer. The lowest values are from zones of continental extension. Highly oxidized xenoliths (fo(2) greater than FMQ) come from regions of recent or acive subduction (for example, Ichinomegata, Japan), are commonly amphibole-bearing, and show trace element and isotopic evidence of fluid-rock interaction. Peridotites from ocean ridges are reduced and have an averae fo(2) of about -0.9 log units relative to FMQ, virtually coincident with values obtained from mid-ocean ridge basalt (MORB) glasses. These data are further evidence of the genetic link between MORB liquids and residual peridotite and indicate that the asthenosphere, although reducing, has CO(2) and H(2)O as its major fluid species. Incorporation of oxidized material from subduction zones into the continental lithosphere produces xenoliths that have both asthenospheric and subduction signatures. Fluids in the lithosphere are also dominated by CO(2) and H(2)O, and native C is generally unstable. Although the occurrence of native C (diamond) in deep-seated garnetiferous xenoliths and kimberlites does not require reducing conditions, calculations indicate that high Fe(3+) contents are stabilized in the garnet structure and that fo(2) deareases with increasing depth.     

稀土化合物影响红豆杉细胞紫杉醇释放行为研究

通过对东北红豆杉细胞紫杉醇短期释放行为的研究,发现细胞内外紫杉醇的分布均呈振荡变化。稀土化合物的加入对紫杉醇细胞内外分布有显著的影响。对如何使东北红豆杉细胞转化为紫杉醇分泌型细胞进行理论性的探讨。     

稀土元素对农田生态系统的影响研究进展

稀土矿的开采和冶炼、稀土农用等导致农田土壤稀土元素含量不断积累,对农田生态系统结构和功能稳定产生严重的影响。综述了近20年来国内外农田生态系统稀土元素的主要来源、分配和输出,土壤和植物中稀土元素的测定方法,稀土元素对农田生态系统中植物、微生物、动物以及人类健康影响的研究进展。探讨了农田生态系统稀土元素的毒性评价和稀土污染土壤的修复措施。最后提出开展稀土元素对农田生态系统影响研究还需要加强的一些问题。     

KCl肥料中稀土元素含量分析

[目的]确定农业上经常应用的钾肥KCl中的稀土元素,为今后的钾肥肥效试验和农业生产提供基础数据。[方法]应用ICP-MS法详细分析了钾肥KCl中的稀土元素含量。[结果]KCl肥料中含有15种稀土元素,分别是:La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu和U,它们的含量分别为:61.74、110.73、11.363、2.55、6.452、.89、3.83、0.681、.980、.68、1.11、0.230、.66、0.30和0.73 ng/g。但是没有检测到Th。[结论]市场销售肥料含有多种杂质元素,特别是稀土元素在浓度较低时就会对植物产生明显影响,建议在做肥效试验时应初步了解肥料中稀土元素含量。