太原市大气扩散数值模拟

本文采用数值方法求解平流扩散方程，对太原市的一次示踪物实验进行了大气扩散的数值模拟。模拟结果表明：采用数值方法准确地反映出了由于风的切变而导致的污染物烟羽的转向，能较好地模拟复杂地形下太原市污染物的输送扩散过程。     

从地名看开疆文化在海南岛的传播扩散

开疆文化是一种开发，开拓边疆的文化，开疆文化的传播是通过众多文化要素的逐渐渗透，传输而实现整体状况改变的，开疆文化在海南的传播扩散及其历史影响则又可以从地名等文化要素的演变中得到反映，进而从一个侧面印证开疆文化在海南岛的传播，扩散及影响。     

乌鲁木齐集聚扩散的空间分析

城市的集聚扩散涉及政治、经济、文化、科技、信息等，其中实质性的是经济的集聚和扩散。集聚扩散的强度与距中心城市的远近有关，距离越远，强度越小。集聚扩散的方式主要通过人口流、物质流、信息流、技术流来实现。基于大量的调查资料，采用定量、定性相结合的方法，对乌鲁木齐的空间集聚扩散的范围和强度做具体的分析和探讨。     

胶南榴辉岩矿物氧同位素平衡及其Sm-Nd年代学制约

对苏鲁地体中的胶南榴辉岩进行了矿物氧同位素分析，并与同一手标本矿物的Sm-Nd内部等时线定年和Nd-Sr同位素分布进行了对比。研究表明，石榴子石与绿辉石之间的氧同位素平衡与否能够对矿物Sm-Nd同位素体系的平衡状况和内部等时线定年结果的有效性给予直接制约。合理的石榴子石＋绿辉石Sm-Nd内部等时线年龄产于两矿物之间达到并在峰变质条件下保持氧同位素平衡的样品中，而两矿物之间处于氧同位素不平衡的样品不能给出正确的Sm-Nd内部等时线年龄。同一矿物在手标本尺度出现显著的O-Nd-Sr同位素不均一性，据此对这些元素在石榴子石和绿辉石中的扩散速率顺序进行了估计，不仅得到了与实验扩散系数相吻合的结果，而且由此估计出在峰变质条件下达到矿物内部同位素均一化所需要的时间应大于10Ma。     

一个改进的湍流垂直扩散过程参数化方案

研究了数值天气预报模式中次阿格湍流垂直扩散过程的参数化问题。以Ｂｏｕｇｅａｕｌｔ和Ｌａｃａｒｒｅｒｅ（１９８９）的参数化方案为基础，改进了处理湍流混合长的方法，使湍流混合长和热力混合长分别依赖于基本气流的静力稳定度和风场切变。新方案的基本思路是把ＶｏｎＫａｒｍａｎ（１９３０）提出的动力（风场切变）湍流扰动假设与ＢＬ－８９方案提出的热力（静力稳定度）湍流扰动假设结合在一起，强调了大气的热力结构、动力结构和湍流动能对湍流混合过程的共同影响。新方案和ＢＬ－８９方案的二维对比数值试验结果表明，在大气处于静力较稳定而风场切变明显条件下的湍流扰动表现能力方面，新方案比原方案有明显的改进。     

高分辨区域输送模式中不同输送格式的对比试验

本文对两种输送格式在理论试验的基础上，引入19层高分辨区域输送模式EM3，由中尺度模式（MM4)提供实例输送风场，积分至13、18、30、50、70小时，作分析和对比数值试验。采用的两种格式是:二阶动量矩守恒的Prather格式（以下简称为SOM)及通量订正的Smolar格式。数值试验结果表明，高精度的SOM格式使数值扩散减小一个量级， 使输送物质（SO#-[2])中心浓度比Smolar格式增大3～4倍， 采用SOM格式还明显改进了浓度中心水平平均运动轨迹的模拟精度，选择高精度的平流格式是改进模拟结果的重要途径。     

A comparative allometric study of the morphometry of the gills of an alkalinity adapted cichlid fish,Oreochromis alcalicus grahami,of Lake Magadi,Kenya

A morphometric analysis of the gills ofOreochromis alcalicus grahami has been carried out on specimens from ecologically distinct lagoons and a water-holding tank of Lake Magadi, a highly alkaline salt lake situated in a volcanically active region of the southern part of the Great Rift Valley in Kenya. The data were compared with those fromOreochromis niloticus, a close relative that lives in fresh water and with data from other fresh water and marine fish. Our primary goal was to identify the possible adaptive features which enable the fish to survive in an environment characterized by severely fluctuating levels of oxygen, a condition exacerbated by factors such as high temperature, alkalinity and osmolarity. The specimens ofO. a. grahami from the south-western lagoons of the lake had gills better adapted for gas exchange with a body mass specific diffusing capacity for oxygen which was about 2 times greater than that of the gills of the specimens from the fish spring lagoons and 2.5 times that of those from the water-holding tanks. Some parameters of the gills ofO. a. grahami, e.g. the gill filament length and number of gill filaments are significantly greater than those ofO. niloticus but the number of secondary lamellae, area of secondary lamellae and the diffusing capacity of the gills are similar in the two species. Compared with most other fish, the gills ofO. a. grahami appear to be particularly well adapted for gas exchange especially by having a thin water-blood barrier. Perhaps in no other extant fish have the gills had to be so exquisitely designed to meet environmental extremes and regulate complex and at times conflicting functions such as gas exchange, iono-regulation, acid-base balance and nitrogenous waste excretion as inO. a. grahami     

A Eulerian air pollution model for Europe with nonlinear chemistry

A long-range transport model with nonlinear chemical reactions is described. The model contains 35 pollutants and 70 chemical reactions. This is a Eulerian model defined on a space domain containing the whole of Europe. The spherical space domain (corresponding to the Earth's surface covered by the model) is mapped into a square plane domain and discretized by using a 32×32 grid. The grid increments are equidistant (both along the Ox axis and along the Oy axis). The choice of values of the physical parameters involved in the model and the numerical treatment of the model are shortly discussed. The model is tested with meteorological data for 1985 and 1989. The numerical results are compared with measurements at stations located in different European countries. Extensive comparisons of ozone concentrations for July 1985 with measurements taken at 24 European stations are also carried out. Results concerning three episodes in July 1985 as well as results obtained in the study of the sensitivity of the ozone concentrations to variations of NO _x and/or anthropogenic VOC emissions are presented. The advantages and the limitations of such a model are discussed. The model is continuously improved by adding new modules to it. The plans for improvements in the near future are outlined.     

Textural analysis and modelling of a flood deposit: River severn,U.K.

Samples of sediment collected from the Severn floodplain between Worcester and Gloucester following the severe flooding in January and February 1990, were analysed for their grain size distribution. The results show that most sand was deposited within 20 m of the channel bank, but that fine sand may contribute to flood sediment across the width of the floodplain. James' (1985) numerical model of overbank sedimentation attempts to predict the transfer of sediment to the floodplain during flooding. Geometrical and hydraulic data relating to the Severn flood are used as input for a computer program of James' (1985) model. The pattern of sediment concentrations predicted by the model was compared with that obtained from statistical analysis of the flood sediment. The patterns were found to be similar, so James' (1985) model was considered to predict in a relative sense the distribution of flood sediment.     

载金石英的化学成分特征及其意义

利用电子显微镜(EM)及能谱仪(EDS),分析研究了变生热液形成的载金石英的化学成分、离子扩散作用以及金在石英中的赋存状态等问题,探讨了它们的形成和变化机理。研究结果表明:Al~(3+)、Ti~(3+)、TFe、Na~(+)、K~(+)、Ca~(2+)等在石英中为类质同像混入物;石英和黄铁矿之间的离子相互扩散作用,表现为石英中Al离子的带出和Fe离子的带入,黄铁矿中Fe离子的带出和Al离子的带入;石英中呈分散状态分布的金主要为离子金,它们充填在石英结构中,起平衡电价的作用。