莱洲湾沿岸浅层地下卤水蒸发成因新依据     

李伟  吴衍华 《山东国土资源》2007,(Z1)

山东莱洲湾沿岸是我国重要的天然卤水矿产地,分布广、浓度高、储量大,关于其成因通过近几十年来的研究可归纳为蒸发浓缩生卤和冰冻生卤2种,但其依据尚不够丰富。该文从海水冰冻实验与蒸发实验所经历的路径中,Na/Cl与Ca/Mg随浓缩倍数的变化趋势来分析卤水的成因,认为其应属蒸发浓缩生卤。  相似文献   

美丽中国建设的理论基础与评估方案探索   总被引：5，自引：2，他引：5  

方创琳  王振波  刘海猛 《地理学报》2019,74(4):619-632

美丽中国建设是关系中华民族永续发展的根本大计,也是落实到2030年联合国可持续发展议程的中国实践。党和国家针对“五位一体”的总体布局对建设美丽中国做出了战略部署,国家主席习近平在全国生态环境保护大会上进一步提出了美丽中国建设的“时间表”和“路线图”。但目前对美丽中国建设的理论基础、评估指标体系、评估标准及建设成效等问题并不清晰。本文从广义和狭义视角提出了美丽中国建设的基本内涵,将人地和谐共生论、五维一体美丽论作为美丽中国建设的核心理论基础,进一步构建了包括生态环境、绿色发展、社会和谐、体制完善、文化传承等5个维度的美丽中国建设评估指标体系,运用联合国人类发展指数（HDI）测评方法,对2016年中国341个地级市（州）的美丽中国建设成效进行了科学评估。结果显示,美丽中国建设的综合美丽指数（中科美丽指数）平均值为0.28,总体处于偏低水平,生态环境美丽指数、绿色发展美丽指数、社会和谐美丽指数、体制完善美丽指数和文化传承美丽指数分别为0.6、0.22、0.29、0.22和0.07,分项指数值均较低,且地域发展差异较大,说明美丽中国建设进程总体缓慢且不平衡。为了高质量、高标准地贯彻落实美丽中国建设的“时间表”和“路线图”,建议构建并发布通用的美丽中国建设进程评估体系,对美丽中国建设进程开展动态监测与阶段性综合评估,编制并发布美丽中国建设评估技术标准,做好美丽中国建设综合区划,分区域因地制宜地开展美丽中国样板区建设试点,并把美丽中国建设成效纳入各级政府考核指标。  相似文献   

Redefining the trophic importance of seagrasses for fauna in tropical Indo-Pacific meadows   总被引：2，自引：1，他引：1  

Jan Arie Vonk  Marjolijn J.A. Christianen  Johan Stapel 《Estuarine, Coastal and Shelf Science》2008,79(4):653-660

Fauna species living in seagrass meadows depend on different food sources, with seagrasses often being marginally important for higher trophic levels. To determine the food web of a mixed-species tropical seagrass meadow in Sulawesi, Indonesia, we analyzed the stable isotope (δ¹³C and δ¹⁵N) signatures of primary producers, particulate organic matter (POM) and fauna species. In addition invertebrates, both infauna and macrobenthic, and fish densities were examined to identify the important species in the meadow. The aims of this study were to identify the main food sources of fauna species by comparing isotopic signatures of different primary producers and fauna, and to estimate qualitatively the importance of seagrass material in the food web. Phytoplankton and water column POM were the most depleted primary food sources for δ¹³C (range −23.1 to −19.6‰), but no fauna species depended only on these sources for carbon. Epiphytes and Sargassum sp. had intermediate δ¹³C values (−14.2 to −11.9‰). Sea urchins, gastropods and certain fish species were the main species assimilating this material. Seagrasses and sedimentary POM had the least depleted values (−11.5 to −5.7‰). Between the five seagrass species significant differences in δ¹³C were measured. The small species Halophila ovalis and Halodule uninervis were most depleted, the largest species Enhalus acoroides was least depleted, while Thalassia hemprichii and Cymodocea rotundata had intermediate values. Fourteen fauna species, accounting for 10% of the total fauna density, were shown to assimilate predominantly (>50%) seagrass material, either directly or indirectly by feeding on seagrass consumers. These species ranged from amphipods up to the benthic top predator Taeniura lymma. Besides these species, about half of the 55 fauna species analyzed had δ¹³C values higher than the least depleted non-seagrass source, indicating they depended at least partly for their food on seagrass material. This study shows that seagrass material is consumed by a large number of fauna species and is important for a large portion of the food web in tropical seagrass meadows.  相似文献   

A new approach to null correlations of proportions   总被引：1，自引：0，他引：1  

J. Aitchison 《Mathematical Geology》1981,13(2):175-189

Much work on the statistical analysis of compositional data has concentrated on the difficulty of interpreting correlations between proportions with an assortment of tests for nullcorrelations, for independence except for the constraint, F-independence of bounded variables, neutrality in the mean and in the median. This paper questions the appropriateness of characterizing the dependence structure of proportions in terms of such concepts, suggests an alternative method of modeling, develops necessary distribution theory and tests, and illustrates the methodology in applications.  相似文献   

基于紧支径向基函数的点插值无网格方法     

孔亮  高学军  王燕昌 《岩土力学》2004,25(Z2):117-120

紧支径向基函数能使支配方程中的刚度矩阵具有稀疏性,很适合应用于无网格方法中,其缺点是在插值计算时精度不高.点插值方法的插值函数具有Delta函数性质,可以很方便的施加本质边界条件,但在计算插值函数时矩阵易出现奇异.为了提高计算精度并避免点插值法的局限性,首先对紧支径向基函数进行完备性修正,然后用完备性修正的紧支径向基函数代替多项式来形成插值函数,建立了紧支径向基函数点插值方法.由于该方法中的形函数满足Delta函数性质,因此本质边界条件可以像传统的有限元方法一样很容易施加.然后将该方法用于二维弹性静力问题的求解,导出了其相应的离散方程.最后将该方法应用于一个悬臂梁的分析中,初步验证了该方法的有效性与合理性.  相似文献   

利用流体包裹体分析东营凹陷古压力   总被引：2，自引：0，他引：2  

李善鹏邱楠生  曾溅辉 《华东地质学院学报》2004,27(3):209-212

流体包裹体是盆地流体的原始样品，它记录了地质历史中盆地流体的很多信息。通过研究流体包裹体可以得出其成藏环境的原始古压力，这在石油地质领域中具有重要的意义。文章以东营凹陷为例利用流体包裹体分析了其古压力。结果表明，东营凹陷在包裹体被捕获时就具有了异常高压，以后随着埋藏作用和油气充注的进行，异常压力值也在增大，从而表明利用流体包裹体研究沉积盆地古压力是一种行之有效的方法，能够为古压力的研究提供可靠的依据。  相似文献   

The application of commutative algebra to geodesy: two examples     

J. L. Awange  E.W. Grafarend  Y. Fukuda  S. Takemoto 《Journal of Geodesy》2005,79(1-3):93-102

Algebra, in particular commutative algebra, is applied here to provide a general unified solution to nonlinear systems of equations encountered in geodesy. Starting with the “Abelian group”, the “polynomial ring” is defined and used to form generators of ideals. By applying Buchberger or polynomial resultant algorithms, these generators are reduced to simple structures often comprising a univariate polynomial in one of the unknowns. The advantage of the proposed unified approach is that it provides exact solutions to geodetic nonlinear systems of equations without the traditional requirements of linearization, iterations or approximate starting values. The commutative algebraic approach therefore alleviates the need for isolated exact solutions to various geodetic nonlinear systems of equations. The procedure is applied to GPS meteorology to compute refraction angles, and Helmert’s one-to-one mapping of topographical points onto the reference ellipsoid.  相似文献   

Stream invertebrate community functional responses to deposited sediment   总被引：3，自引：0，他引：3  

Charles F. Rabení  Kathy E. Doisy  Leanna D. Zweig 《Aquatic Sciences - Research Across Boundaries》2005,67(4):395-402

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A New Type of Neural Network For Reservoir Identification Using Geophysical Well Logs     

Wenzheng Yue  Guo Tao 《Mathematical Geology》2005,37(3):243-260

We have developed a neural network algorithm of radial basis network (RBN) type for geoscience applications. This new probabilistic neural network (PNN), referred to as “gravity-capturing neural network,” employs multidimensional even distance and introduces the resultant force competition mechanism for the output layer. When used for geological pattern recognition with well-logging data, it avoids misjudgment due to a magnitude jump of a single parameter and can extract complex and hidden formulas from laboratory and field measurements more efficiently. A field case study of reservoir identification with geophysical well logs is presented to demonstrate the advantages of this neural network over the conventional PNN in such classification applications.  相似文献   

Latent Compositional Factors in The Llobregat River Basin (Spain) Hydrogeochemistry     

R. Tolosana-Delgado  N. Otero  V. Pawlowsky-Glahn  A. Soler 《Mathematical Geology》2005,37(7):681-702

The study of hydrogeochemical data sets frequently calls for statistical dimension reducing techniques. It is well known that hydrochemical parameters are compositions and, for this type of data, the direct application of classical statistical methods based on the correlation matrix yield spurious results. But new results on compositional data analysis have identified the sampling space, the simplex, with an Euclidean space, a fact that allows us to define a simplicial factor analysis strategy, thus overcoming the problem. For illustration, we use samples from the Llobregat River and its tributaries (NE Spain). Three unobservable or latent factorial components are extracted, which are identified with pristine waters, potash-mining influence and urban sewage influence. These three factorial components or compositional factors are plotted in a factorial ternary diagram, which reflects the relative influence of each one of these factors on each observation.  相似文献