共查询到20条相似文献，搜索用时 125 毫秒
1.
应用带能谱的电子扫描电镜(SEM-EDX)对拉萨市夏季正常天气下收集的大气自然沉降气溶胶样品进行分析,研究了拉萨市大气降尘矿物组成和各种物相形貌特征信息。拉萨市大气颗粒物含有硅酸盐颗粒、富钙颗粒、富铁颗粒、富碳颗粒(燃煤飞灰颗粒和燃油飞灰颗粒)和植物残体颗粒。根据颗粒物数量统计发现拉萨市大气颗粒物以硅酸盐颗粒为主,富钙颗粒和富铁颗粒次之,需要指出的是以燃油飞灰为主的富碳颗粒已占到一定比重,说明以燃油为主的机动车尾气对拉萨大气污染在加强。研究结果表明,大气降尘矿物成分及其形貌特征可以用作判定污染物来源的重要标志,拉萨大气中颗粒来源的多样性决定了治理措施也应综合进行。 相似文献
2.
唐山大气降尘的矿物组成与微观形貌特征分析 总被引：1，自引：0，他引：1
应用X射线衍射线技术(XRD)和扫描电镜技术(SEM/EDX)对唐山大气降尘中颗粒的矿物组成及微观形貌进行了研究。结果表明,唐山大气降尘的主要矿物组分是方解石、石英和粘土,次为赤铁矿、石膏、白云石及长石类矿物,其它的矿物还有菱铁矿、菱镁矿、石盐、沸石、角闪石、钙芒硝和无水芒硝等;其形貌特征主要有球状、层状、片状、柱状和块状等规则形态及矿物单体和矿物集合体等不规则形态;对XRD的检测结果进行分析后,表明大气降尘颗粒物的主要来源为地面扬尘、建筑扬尘、工业尘及在大气环境中新生成的矿物。 相似文献
3.
4.
北京市中关村地区大气降尘的来源与垂向分布特征 总被引：1，自引：0，他引：1
利用光学和电子显微镜、X射线衍射仪以及同步辐射X射线荧光对北京市中关村地区大气降尘的粒度分布、颗粒物微观形貌特征、矿物组成及化学元素组成等方面进行分析研究。粒度分析表明中关村地区大气降尘随着相对高度的增加,粗颗粒物逐渐减少。大气降尘的颗粒物形貌可以分为粒状、柱状单矿物,圆球状飘珠和不规则粒状集合体3种类型。矿物组成及化学元素组成的分析显示中关村地区大气降尘的污染物主要来自自然扬尘、建筑扬尘、燃煤、汽车尾气等污染源。 相似文献
5.
《地球化学》2020,(3)
矿物沙尘气溶胶作为大气气溶胶的重要组成,全球年排放量高达约2000 Tg,主要分布在非洲、亚洲和北美等地沙漠区域。以往研究表明,不同源区的沙尘矿物组分往往存在一定差异,表现为不同源区形成的矿物气溶胶在大气中的理化性质存在差异,如吸湿性、光学性质以及云凝结核活性等,导致沙尘在传输、降尘的过程中对环境、气候以及生物地球化学循环产生不同的重要影响。此外,不同的矿物沙尘颗粒,会引起各种呼吸系统疾病以及皮肤病等,对人体健康产生极大危害。现阶段对于大气颗粒物矿物组成主要的检测手段包括X射线衍射(XRD)光谱、傅里叶红外光谱、扫描电子显微镜和透射电子显微镜等。其中XRD技术能够高效、准确、快速和无损害地完成对样品的物相鉴定,是现阶段检测矿物相的主要技术手段,伴随其分析方法及软件的不断改进,检测结果更加精准。本次工作综述了XRD应用于大气颗粒物研究的具体分析方法以及在亚洲、北非等地沙尘颗粒的研究进展,同时汇总了各种物相鉴定方法以及存在的问题,旨在为大气颗粒物的矿物组成识别手段建立一定的选择依据。 相似文献
6.
北京及其北部地区大气自然降尘矿物组成特征 总被引：1，自引：0，他引：1
为研究北京地区大气自然降尘的矿物组成特征及其时空变化规律,采用XRD分析了不同季节收集的大气降尘样品。结果表明,大气降尘主要矿物为石英,平均含量为83.19%,长石以斜长石为主;降尘中的碳酸盐类矿物主要是方解石和白云石,它们在降尘中的含量接近其在北方黄土中的含量;降尘中粘土矿物的含量较少,为1.64%~5.88%,其中有较多的高岭石,反映了研究区半湿润、较温暖的环境。聚类分析表明本区降尘按矿物组成特征可分为城市和郊区两组。与大风天气少的月份相比,大风天气频繁的月份降尘中的长石等矿物含量相对较高,而粘土矿物含量相对较低。 相似文献
7.
用多晶X-射线衍射法对淄博市中心城区逐月采集的大气降尘矿物组成及其含量进行了分析。研究结果表明:淄博市大气降尘的矿物组合比较稳定,降尘中以源于自然成因的石英、长石和粘土质矿物为主,质量分数变化范围为59.1%～95.1%。降尘中的石膏和方解石与大气化学反应有关,其中石膏质量分数为36.3%～1.0%,反映了大气SO2污染具有明显的时间性特征。降尘中的赤铁矿源于高温工业活动,含量变化幅度最小。气象因素可能是导致降尘中石膏含量变化的主要原因,降尘中石膏含量的变化是大气酸污染程度的重要矿物指示剂。 相似文献
8.
利用电子探针对南昌市降尘颗粒物的形貌特征和成分进行了分析,并探讨了它们的来源.得出南昌市降尘颗粒物的主要组成为矿物颗粒、钙质颗担以及块状烟尘集合体和燃煤飞灰颗粒.不同功能区的采样点颗粒物的组成有一定差异,表明颗粒物的来源不同.根据颗粒物的来源和分布特点,认为南昌市的城市规划布局不甚合理,尚需进一步改善. 相似文献
9.
大气降尘矿物学特征研究具有重要的环境学意义。文章以华北理工大学校区采集样品为例,应用激光粒度分析仪、扫描电镜、X射线粉末衍射、电感耦合等离子体质谱等对河北省唐山市曹妃甸地区大气降尘矿物学特征进行了初步分析研究。结果表明,曹妃甸地区大气降尘粒径较粗,颗粒物包括块状、柱状、片状、球状及不规则粒状集合体,主要由石英、长石、石膏、云母、绿泥石、角闪石、白云石、方解石和赤铁矿等矿物组成;降尘样品中Cr、Cu、Zn、As、Cd、Pb等重金属元素含量均较高。研究分析表明,降尘样品中硅酸盐矿物主要源自地面扬尘,而石膏、方解石等碳酸盐矿物可能为环境中的次生矿物,样品中重金属污染主要来源于燃煤、工矿企业生产排放和少部分汽车尾气排放。 相似文献
10.
11.
Guboglo M. N. 《GeoJournal》1980,4(1):53-58
International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen. 相似文献
12.
13.
Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated. 相似文献
14.
Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth
B. P. Kondratyev 《Astronomy Reports》2017,61(8):709-714
It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T 3 = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″. 相似文献
15.
位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压，而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩，榴辉岩及其他直接围岩皆呈包体存在于其中，并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体，表明新元古代花岗岩的组成物质也经受过超高压变质作用，且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次（或阶段）却少于榴辉岩。椐上述可得如下推断：超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部（俯冲板块前部）形成的；榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的，其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升，遭受剥蚀。 相似文献
16.
17.
摩擦桩基桩土间极限摩阻力取值问题探讨 总被引：1，自引：0，他引：1
通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。 相似文献
18.
某高速公路下伏煤矿采空区稳定性分析 总被引：10，自引：0，他引：10
在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。 相似文献
19.
The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time. 相似文献
20.
Michel Westphal Mikhail L. Bazhenov Jean Paul Lauer Diamar M. Pechersky Jean-Claude Sibuet 《Tectonophysics》1986,123(1-4)
We first re-examined the apparent polar wander curves for stable Eurasia and Africa since the Triassic. These curves were then combined together with curves of North and South America according to the kinematics of the Atlantic ocean and a synthetic polar wander curve was given. Then, most of the paleomagnetic results from the Tethys mobile belt, from the Atlantic to the Pamirs, were analysed.Several groups of plates, microplates and blocks can be seen. First, relatively stable regions like Maghreb and Sicily, which have not moved much. Then we have a group formed by Iberia, Sardinia, Italy and, to a lesser extent, Corsica and the Western and Central Alps. For these blocks, movements are anticlockwise rotations chiefly driven by the anticlockwise rotation of Africa, but they are sometimes stronger.To the east, a major change takes place. The north of the Aegean Sea and the Ionian zone are clockwise rotated and these rotations are recent: Oligocene-Miocene for the first part, Pliocene to the present for the second part.A major problem arises in Turkey, Caucasus and Iran. Paleomagnetic results indicate a position far to the south of Eurasia, and, at the same time, geological evidence is in favour of a position close to Eurasia. We discuss these discrepancies. 相似文献