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1.
蒸发皿中水面蒸发氢氧同位素分馏的实验研究   总被引:3,自引:0,他引:3  
气象要素与蒸发密切相关,通过室内外不同气象条件下的器皿水蒸发实验,获得了水面蒸发氢氧稳定同位素分馏因子与气象要素的关系。实验结果表明,随着蒸发的进行,剩余水体中逐渐富集重同位素;自由水体蒸发同位素分馏在垂线上有分层现象,表层水体同位素值比垂线平均的同位素值略富集;不同温度条件下的室内蒸发实验中,温度越高,液-气间分馏系数越小,相应于同一剩余水体体积比,剩余水体稳定同位素值则越低。室外器皿水自由蒸发实验中得出的蒸发线方程斜率较大地偏离了当地降水线,表明实验期间水体蒸发分馏作用较明显。该研究为进一步揭示水体蒸发分馏规律提供了可靠的实验依据。  相似文献   

2.
水体蒸发过程中稳定同位素分馏的模拟   总被引:13,自引:3,他引:13  
通过对非平均条件下水体蒸发中稳定同位素分馏机制的分析。模拟了蒸发水体中稳定同位素比率的变化及与温度,大气温度的关系。在瑞利模式中,剩余水中的稳定同位素随剩余水比例f的减小不断富集,富集的速率与温度呈反比,在动力蒸发条件下,稳定同位素的分馏不仅与相变温度有关,而且受大气湿度和液-气相之间物质交换的影响。在动力蒸发过程中,相对湿度越小,剩余水中稳定同位素比率随f的变化越快,当相对湿度较大时,在经历了一段时间蒸发后的剩余水中的δ将不随f变化。蒸发水体达到稳定状态的速率主要取决于大气的相对湿度。当温度约20℃时,在瑞利平衡条件下模拟的蒸发线与全球大气水线较接近。在非平衡蒸发条件下。蒸发线的梯度项和常数项与温度和相对湿度呈正比。  相似文献   

3.
基于瑞利分馏模式的水体蒸发线斜率模型   总被引:4,自引:0,他引:4       下载免费PDF全文
瑞利分馏模式是研究水体蒸发同位素变化规律的重要方法。分析了瑞利分馏中分馏系数的影响因子,基于瑞利分馏模式推导了自由水体蒸发线斜率理论方程。分析了湿度和温度因子对于蒸发线斜率的影响。结果表明,在温度不变的情况下,蒸发线斜率随着湿度的增加而减少;在湿度不变的情况下斜率随着温度的升高而增大。利用黄河中游地区的湿度和温度气象因子,基于该斜率模型模拟了黄河中游地区地表水体蒸发线斜率,并进行了实例验证。  相似文献   

4.
稳定性氢氧同位素在水体蒸发中的研究进展   总被引:3,自引:0,他引:3  
介绍了同位素分馏的基本概念以及利用稳定同位素研究水体蒸发的基本原理。综述了国内外对水体蒸发中稳定同位素分馏机制的研究,分析了温度、湿度等气象因子对蒸发同位素分馏的影响,对动力分馏模型进行了详细推导,概述了利用同位素估算蒸发量的方法。指出了国内这方面研究的不足,并展望了今后的研究趋势。  相似文献   

5.
河道水体中氢氧稳定同位素组成的微分方程模型   总被引:2,自引:0,他引:2       下载免费PDF全文
介绍了前人提出并被广泛应用的瑞利分馏模型,指出了其优缺点。针对其不足,在作了一定的假定和简化的前提下,基于瑞利分馏原理和水力学基本定律分别推导了:①静止水体的氢氧稳定同位素组成随时间变化的微分方程模型,揭示了静止水体的同位素组成与时间、分馏系数和蒸发率之间的关系;②河道中运动水体的同位素组成随时间和空间变化的微分方程模型,导出了河道运动水体中稳定同位素组成与分馏系数、流速、流量、蒸发率之间的定量关系。最后通过数学推导论述了上述各模型之间的内在联系。上述模型的建立为定量计算和精确模拟运动水体中氢氧稳定同位素组成的变化提供了确定性的数学基础,也为更客观、更充分的解译水的稳定同位素数据提供了帮助。  相似文献   

6.
华北平原典型区水体蒸发氢氧同位素分馏特征   总被引:3,自引:0,他引:3       下载免费PDF全文
马斌  梁杏  靳孟贵  李静  牛宏 《水科学进展》2015,26(5):639-648
为研究华北平原衡水地区水体蒸发氢氧同位素分馏特征,采集不同盐度的深层地下淡水(TDS 为0.61g/L)和浅层地下咸水(TDS为7.97g/L),现场开展室外器皿蒸发实验,获得了当地气象条件下氢氧同位素分馏参数.实验结果显示,淡水及咸水剩余表层水δ18O与剩余水比率f呈指数关系,与瑞利分馏模拟结果一致,δD和δ18O蒸发线斜率分别为4.78和4.69.整个蒸发过程中,淡水及咸水氢氧同位素值增量ΔδD分别为Δδ18O的4.82倍和4.76倍;剩余表层水相对于初始水δD和δ18O的变化量与累积蒸发量之比,淡水分别为2.68‰/cm和0.56‰/cm,咸水分别为2.78‰/cm和0.61‰/cm;而在不同的蒸发时段,剩余表层水δD和δ18O的变化量与蒸发量无明显相关性.受水分子扩散的影响,蒸发皿中氢氧同位素分馏在垂线上分层微弱.由于水体盐度较低,在当地气候条件下进行自由蒸发时,氢氧同位素分馏的盐效应可以忽略.  相似文献   

7.
<正>硅元素的丰度在地壳中仅次于氧,是所有硅酸盐矿物的主要成分。然而,有关于地球表层系统(即土壤、水体、植物)的硅同位素分布问题还存在许多不解之处。比如,Georg等(2007)和Hughes等(2013)在室温下由瑞利模型推导的黏土和其溶液的硅同位素平衡分馏系数分别为Δ30Siclay-solution=-1.5‰和-2.05‰,这明显违背化学键越强越富集重同位素的常识。理论上,沉淀的矿物由于其相对于溶液中的H4SiO 4具有较短的Si-O键会优先富集重同位素。类似的现象还存在于石英与溶液的分馏过程。绝大多数现场观测表明,  相似文献   

8.
蒸发浓缩作用是引起水体咸化的重要原因。利用华北浅层地下水样,设计持续蒸发和补给蒸发两种实验方案,探讨不同蒸发过程中水化学和同位素的演化差异。结果表明,持续蒸发过程中水体盐分浓缩速率明显大于补给蒸发;Ca~(2+)和HCO_3~-在两种蒸发实验下出现分离,主要受方解石沉淀影响,Mg~(2+)、Na~+、K~+、Cl~–和SO_4~(2-)含量随着盐度的升高而增加,在两种蒸发实验中无差异。蒸发过程中,氢氧同位素逐渐富集,与剩余水比例呈指数关系,与阴阳离子呈两段式线性关系。持续蒸发过程中氢氧同位素随着盐分(电导率)的升高逐渐富集,δ~(18)O最大值达20.81‰,蒸发线方程为δD=4.11δ~(18)O–25.23;而补给蒸发过程中,随着盐分(电导率)的增加氢氧同位素富集缓慢,后期相对稳定,δ~(18)O最大值为2.9‰,蒸发线方程为δD=3.41δ~(18)O–28.2。两种实验方案结果说明氢氧同位素在水相的富集不成比例,氢同位素在蒸发过程中富集速率大于氧同位素。  相似文献   

9.
利用稳定同位素大气水平衡模式(iAWBM)的模拟数据,分析了在不同的下垫面蒸发和不同的凝结分馏条件下降水中δ~(18)O的时间变化、降水量效应、负温度效应和大气水线。并通过与长沙站5年实测数据的比较以及模拟试验结果之间的相互比较,揭示下垫面蒸发水汽中稳定同位素的季节性变化和云中稳定同位素分馏对降水中稳定同位素变化的可能影响,增进对季风区水稳定同位素效应的理解和认识。iAWBM给出的4个模拟试验均很好地再现了监测站降水中δ~(18)O的时间变化,模拟出季风区降水中稳定同位素在暖半年被贫化、在冷半年被富集的基本特点。与平衡分馏相比,动力分馏下降水中稳定同位素被贫化的程度加强、季节差和离散程度减小;由下垫面蒸发水汽中稳定同位素δ_e季节性变化所引起的降水中稳定同位素的变化在不同季节完全相反:在长沙,暖半年降水中δ~(18)O更低,冷半年降水中δ~(18)O更高,使得降水中稳定同位素季节差和离散程度增大。4个模拟试验均很好地再现了季风区的降水量效应和负温度效应。与平衡分馏相比,动力分馏下模拟的降水量效应和负温度效应的斜率相对较小;δ_e季节性变化导致模拟的降水量效应和负温度效应的斜率增大。利用iAWBM,模拟出季风区湿热气候条件下的MWL。动力分馏以及δ_e季节变化均使模拟得到的MWL的斜率和截距减小。  相似文献   

10.
微生物降解使有机化合物的稳定碳、氢同位素发生不同程度分馏的研究在有机污染物来源和微生物环境修复等领域取得了长足进展,并对原油和天然气微生物降解研究有借鉴意义。微生物作用下的同位素分馏为动力同位素分馏,导致重同位素在残余物中富集。影响微生物降解有机物同位素分馏的主要因素有微生物的降解代谢途径、辅酶作用、降解类型与程度、同位素质量差异和有机物碳数等。不同的微生物代谢途径代表不同的生物化学反应,造成了同位素分馏的显著差异;辅酶对反应的催化作用使微生物作用造成的同位素分馏更加复杂。低碳数正构烷烃遭受微生物降解程度越高,碳、氢同位素的分馏也越大,同位素变重与降解程度之间有明显的相关性。但对于复杂化合物,由于降解的多级反应,同位素分馏与降解程度间的相关性并不明显。在同样降解程度下,氢同位素分馏大于碳同位素分馏,低碳数正构烷烃的同位素分馏大于高碳数正构烷烃的同位素分馏。  相似文献   

11.
东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。  相似文献   

12.
In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.  相似文献   

13.
郯庐断裂南段研究进展与断裂性质讨论   总被引:13,自引:3,他引:13  
据1:5万区域地质调查和专题研究资料,就郯庐断裂带是否南延与消失的原因,其与大别—苏鲁造山带交截形成的假位错效应,以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上,讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。  相似文献   

14.
塘口水电站大坝基础座落在断层和裂隙较发育的龟裂纹灰岩上,岩体完整性差、透水性强,多年运行后,大坝灌浆廊道和排水廊道出现多处集中性漏水,为确保大坝安全和电站正常发电,根据渗漏性质和成因,采用对灌浆廊道补充帷幕灌浆,对排水廊道进行固结+帷幕+回填灌浆。通过灌浆处理后,效果良好,表明灌浆工程有效的将导致坝基渗漏的上下游的裂隙通道封闭,并顺利的经受了随后的汛期洪水考验,大坝安全得到保障。  相似文献   

15.
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   

16.
In reservoir characterization, the covariance is often used to describe the spatial correlation and variation in rock properties or the uncertainty in rock properties. The inverse of the covariance, on the other hand, is seldom discussed in geostatistics. In this paper, I show that the inverse is required for simulation and estimation of Gaussian random fields, and that it can be identified with the differential operator in regularized inverse theory. Unfortunately, because the covariance matrix for parameters in reservoir models can be extremely large, calculation of the inverse can be a problem. In this paper, I discuss four methods of calculating the inverse of the covariance, two of which are analytical, and two of which are purely numerical. By taking advantage of the assumed stationarity of the covariance, none of the methods require inversion of the full covariance matrix.  相似文献   

17.
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   

18.
The Global Stratotype Section and Point (GSSP) for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy (SSS) proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy (ICS). The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob's Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs.  相似文献   

19.
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   

20.
Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base.  相似文献   

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