地球生态系统的控制能力     

杨东方  秦明慧  石志洲  马祖友  刘炜 《海洋科学》2013,37(12):94-98

随着人类活动的加剧, 环境发生了巨大的变化。从地球生态系统的角度来探讨和研究全球的环境变化, 具有重要的意义。通过对北太平洋海洋生态系统的剖析, 在时间和空间尺度上, 展示了地球生态系统强有力地控制着陆地的沙尘暴、大气的北太平洋季风和海洋的硅来源及输送方式。为了保持向海洋输入大量的Si, 地球生态系统控制着陆地生态系统、大气生态系统和海洋生态系统。研究显示, 地球生态系统使北太平洋的季风与北太平洋边缘的雨季在时间上密切相嵌, 顺利完成近岸洪水和河流的输送与大气的输送之间的相互转换; 同时也使沙尘暴与北太平洋Si 的缺乏在时间上紧密配合, 其强度大小与Si 缺乏的严重程度相一致。因此, 在全球的环境变化下, 海洋Si 的缺乏是在严重加剧。那么, 地球生态系统展示了强有力的控制能力, 维持向海洋水域提供大量的硅, 充分保证海洋生态系统的健康发展。  相似文献   

白云鄂博矿床Si同位素特征及其成矿示踪作用     

万德芳  蒋少涌 《地球学报》1997,18(Z1):208-210

本文试图从Si同位素研究的角度，为判断矿床成矿物质来源和矿床成因提供新的信息。  相似文献   

北京门头沟地区棋盘岩铁辉长岩的发现及其地质意义     

刘翠  邓晋福  苏尚国  赵国春  李芳凝  赵兴国 《现代地质》2007,21(2):327-331

根据北京门头沟地区棋盘岩岩体的主元素分析结果,按Middlemost提出的TAS分类,有4个样品可以归属为橄榄辉长岩(Peridotgabbro)和似长石辉长岩(Foid Gabbro),属于辉长岩类,并且样品具有高铁(w(FeO*)>14%),贫硅(w(SiO2)<45%)的特征,因此属于铁辉长岩类。这是迄今为止燕山造山带存在铁辉长岩类岩石的首次报道。关于铁辉长岩类的成因目前还有争论,棋盘岩岩体在w(SiO2)-w(FeO*)/w(MgO)图解上显示有Fenner趋势,但是具体的成因还有待于进一步研究。铁辉长岩及其成因的研究将对揭示燕山期北京地区的构造环境和动力学背景、深部过程具有重要的启示意义。  相似文献   

碱性长石Al—Si有序化进程中微结构和^29Si NMR谱的表现   总被引：2，自引：0，他引：2  

薛纪越  周玲棣 《矿物学报》1998,18(3):261-267

笔者用Ｘ射线粉末衍射技术,对六个天然钾长石中的铝在Ｔ１Ｏ四面体位置的占位率进行了测定,它们的Ｔ１Ｏ值从０．２８变化到０．７９。对它们的透射电子显微镜研究表明,两个Ｔ１Ｏ为０．２８和０．３１的高透长石有对电子束异常过敏的调制结构,无法记录到它们的衍射像,在另外三个样品中,都见到芦席状结构,并夹杂着具一定宽度的片晶组成的格子双晶。片晶宽度随Ｔ１Ｏ的变大而增加。而在产于一个霞石正长岩中的正长石中没有观察  相似文献   

Character of the Si and Al Phases in Coal Gangue and Its Ash   总被引：1，自引：0，他引：1  

WANG Lihu  ZHAO Pengda  LI Geng 《《地质学报》英文版》2009,83(6):1116-1121

Abstract: Analysis of the Si and Al phases in coal gangue fuel and its ash is important for use of coal gangue ashes. A comprehensive study by theoretical and experimental analyses with differential thermal analysis, X-ray diffraction and Infrared Spectroscopy has been made in the present article to explore the diagram of the Si and Al phases in coal gangue fuel and its ashes. It is found that kaolinite and quartz are the main phases in coal gangue fuel. The ratio of moles Al2O3 to SiO2 (i.e., Al2O3 (mole) /SiO2 (mole)) is usually no more than 0.5 in most coal gangue fuel and its ashes. The kaolinit at about 984°C releases a large quantity of SiO2, which makes calcine coal gangue more active than coal gangue itself. The relationship between the ratio Al2O3 (mole)/SiO2(mole) and the components of coal gangue ash is analyzed, resulting in a formula to calculate the quantity of each phase. Applying the formula to the testing samples from an electric plant in north China supports the above conclusions.  相似文献   

大水式金矿床稳定同位素、稀土元素地球化学研究   总被引：13，自引：1，他引：12  

闫升好  王安建  高兰  赵彦庆  陈国忠 《矿床地质》2000,19(1):37-45

大水式金太床是近年来在西秦岭地区发现的一个国内外十分罕见的金矿类型,具有极为独特的矿化特征。通过对矿区热液方解石、硅质岩矿石、硅化灰岩及原岩、岩浆岩等地质体碳－氧、硅－氧、碳－氢－氧同位素和稀土元素地球化学特征的系统研究揭示,成矿物质中碳为氧化作用改造的深成岩浆碳,硅具深部岩浆或岩浆热水来源的特点,成矿流体具岩浆水与建造水混合之特点,各种矿石稀土配分曲线和δＥｕ、δＣｅ值均与岩浆岩类似或接近而与地  相似文献   

地下水^32硅年龄的测定方法—液体闪烁计数法   总被引：1，自引：0，他引：1  

周炼  刘存富  王佩仪 《岩矿测试》2000,19(2):97-100

用Fe(OH) 3共沉淀从天然水中提取纯化SiO2 ,回收率在 30 %～ 98% ,然后提取32 P ,将H3PO4溶液和PicoflourLLT混合制备计数溶液 ,用液体闪烁计数法测量32 P的放射性 ,计算32 Si的放射性浓度 ,最后确定地下水的年龄。通过对河北平原浅层地下水的32 Si年龄进行测定 ,所得的32 Si年龄为 92 9 89a± 1 7 87a,与1 4 C的校正年龄一致  相似文献   

Structural characterization of high-pressure C–Na<Subscript>2</Subscript>Si<Subscript>2</Subscript>O<Subscript>5</Subscript> by single-crystal diffraction and <Superscript>29</Superscript>Si MAS NMR     

S. Rakić  V. Kahlenberg  C. Weidenthaler  B. Zibrowius 《Physics and Chemistry of Minerals》2002,29(7):477-484

Single crystals of C–Na₂Si₂O₅ have been synthesized from the hydrothermal recrystallization of a glass. The title compound is monoclinic, space group P2₁/c with Z= 8 and unit-cell parameters a= 4.8521 (4)Å, b=23.9793(16)Å, c=8.1410(6)Å, β=90.15(1)° and V=947.2(2)ų. The structure has been determined by direct methods and belongs to the group of phyllosilicates. It is based on layers of tetrahedra with elliptically six-membered rings in chair conformation. The sequence of directedness within a single ring is UDUDUD. The sheets are parallel to (010) with linking sodium cations in five- and sixfold coordination. Concerning the shape and the conformation of the rings, C–Na₂Si₂O₅ is closely related to β-Na₂Si₂O₅. However, both structures differ in the stacking sequences of the layers. A possible explanation for the frequently observed polysynthetic twinning of phase C is presented. In the ²⁹Si MAS-NMR spectrum of C–Na₂Si₂O₅ four well-resolved lines of equal intensity are observed at ?86.0, ?86.3, ?87.4, and ?88.2?ppm. The narrow range of isotropic chemical shifts reflects the great similarity of the environments of the different Si sites. This lack of pronounced differences in geometry renders a reliable assignment of the resonance lines to the individual sites on the basis of known empiric correlations and geometrical features impossible.  相似文献   

Origin of seleniferous cherts in Yutangba Se deposit,southwest Enshi,Hubei Province   总被引：2，自引：0，他引：2  

姚林波  高振敏  杨竹森  龙洪波 《中国科学D辑(英文版)》2002,45(8):741-754

At the top of the Lower Permian Maokou Formation limestones are developed carbonaceous cherts(Plm3),which constitute the dominant seleniferous layer of the Yutangba Se deposit.The cherts contain as much Se as 1646×10?6 on average.In addition,they are rich in organic carbon,Al2O3,Si2O,but poor in S.In addition to Se,as well as Mo,Cd,V,and Co,etc are also highly enriched in the cherts.The chert samples are characterized by low ?REE,slight LREE enrichment,relatively heavy Si isotope enrichment,and insignificant variations in ? 30Si value within the range of 1.1‰-1.2‰.Generally,it can be judged from the major element,trace element and REE data and the Si isotopic characteristics that the Yutangba seleniferous cherts were formed in the shallow sea to semi-deep sea anoxic environments and their formation is controlled chiefly by bio-chemical processes.  相似文献   

Silicon isotope fractionation between plant parts in banana: In situ vs. in vitro   总被引：1，自引：0，他引：1  

S. Opfergelt  D. Cardinal  C. Henriet  L. Andr  B. Delvaux 《Journal of Geochemical Exploration》2006,88(1-3):224

We recently showed that silicon isotopic fractionation in banana (Musa acuminata Colla, cv Grande Naine) was related to phytolith production, and therefore to silica content in plant. The present study focuses on isotopic fractionation between the different plant parts. Silicon isotopic compositions were measured using a Nu plasma multicollector plasma source mass spectrometer (MC–ICP–MS) operating in dry plasma mode. The results are expressed as δ²⁹Si relatively to the NBS28 standard, with an average precision and accuracy of ± 0.08‰ (± 2σ). On mature banana (Musa acuminata Colla, cv Grande Naine) from Cameroon, δ²⁹Si ranged from + 0.13‰ in the petiole to + 0.49‰ in the lamina, yielding to a 0.36‰ change towards heavier isotopic composition in the upper parts of the plant. This strongly accords with results obtained on in vitro banana plantlets cultivated in hydroponics, where the δ²⁹Si increase from pseudostems to lamina is 0.26‰. These preliminary results on in situ banana show a trend of intra-plant fractionation comparable with that of in vitro hydroponics banana plantlets and with previous data obtained on bamboo.  相似文献