四川峨眉麦地坪剖面震旦系—寒武系界线的新认识及有关化石群的记述

研究剖面位于峨眉山东坡,距峨眉县城约14公里。峨眉山区在大地构造上处于川滇南北向构造带的东侧——峨眉山块断带。震旦系-寒武系出露在蛾眉山背斜两翼,构造简单,地层连续,化石丰富。此剖面先后经过多人研究。     

Pumpspeicherwerke und Hechtbrut—ein Modellversuch

The effects of periodic, simulated water level fluctuations on northern pike fry produced by pumped-storage operations were examined. Daily fluctuations of 10 cm caused a significant increase in the daily mortality rate. Waves reduced the detrimental effect of water level lfuctuations, at least during the adhesive phase of fry.     

天津市北部尔王庄地区末次盛冰期下切河谷特征

渤海湾西岸尔王庄地区钻孔岩芯、微体古生物、孢粉及¹⁴C测年等资料及联合地质剖面研究结果表明，末次盛冰期全球海平面下降使该地区形成下切河谷，冰后期海平面迅速上升引发的海侵造成古河谷的充填，依次形成河床相、河漫滩―河口湾相和三角洲相，与相邻的滦河扇三角洲下切河谷有差异，该下切河谷受海河水系控制，流向大致与古潮白河一致。其演化过程受海平面变化、构造运动和古气候等因素影响，经历了末次盛冰期深切、15~7 ka BP海侵期间河床相及河漫滩―河口湾相的充填和之后海退形成的三角洲相埋藏等三个阶段。     

Simulating nonequilibrium transport of atrazine through saturated soil

Atrazine, an herbicide widely used for selective control of grassy weeds in the fields where maize is grown, is a potential ground water contaminant in China and, consequently, there is interest in predicting its mobility in agricultural soils. In this study, we determined the nonequilibrium transport characteristics of atrazine in Shahe soil (Beijing sandy loam) using the advection-dispersion equation, and using a sensitivity analysis, we evaluated the contribution of the uncertainty in a given input parameter to the overall uncertainty in model results. The asymmetrical shape and tailing of the atrazine breakthrough curve (BTC) showed that atrazine was subject to nonequilibrium transport. The observed atrazine BTC was best fitted by the chemical nonequilibrium model with a nonlinear least-squares optimization approach. Results from the sensitivity analysis indicated that the retardation factor was the most sensitive parameter. Considering the reliability of the estimated parameters, the best fit to the atrazine BTC was obtained by fixing the retardation factor based on the linear distribution coefficient, and by calculating the dispersion coefficient from the bromide BTC and the average pore water velocity from the measured data; nonequilibrium parameters were the only unknown parameters that were optimized. Model verification procedures were based on best-fit parameters optimized from one soil column experiment and applied to simulate the transport of atrazine in the duplicate experiment. The results showed there was good agreement between measured and simulated concentrations for atrazine leaching in the soil column.     

A semi-empirical formula for evaluating residual strain of soils under earthquake loading

A new semi-empirical formula for evaluating the residual strain of soils under earthquake loading is presented in this paper based on the incremental method and the increment model proposed by the authors. When the incident loading is uniform, the results calculated by the new formula are nearly the same as those by the existing formula. For excitation of the random earthquake loading, the results calculated by the new formula are compared to the results obtained by dynamic triaxial tests. The dynamic triaxial tests had been performed considering different seismic waves, confining stresses,consolidation ratios, and types of cohesive soils. The comparison between the calculated and tested results indicate that the presented formula can efficiently and practically describe the time-dependent process of the soil residual strains under actual seismic loads.     

Seismic waves in a layered half-space from an arbitrary buried source

In this paper, a transfer matrix and a three-dimensional dynamic response of a layered half-space to an arbitrary buried source are derived with the aid of a technique which combines the Laplace and two-dimensional Fourier transforms in a rectangular coordinate system. This method is clear in concept, and the corresponding formulas given in the paper are simple and convenient for marine seismic prospecting and other fields' applications. An example is presented and the calculated results are in good agreement with those of the finite element method (FEM).     

北京市大气细粒子的质量浓度特征研究

大气能见度的降低是当今国际上比较突出的城市环境问题。北京近年的监测结果表明 ,大气中通过消光作用使大气能见度下降的气溶胶细粒子的污染程度呈现上升趋势。从 2 0 0 1年对北京市气溶胶细粒子 (空气动力学直径小于 2 .5μm的粒子 ) 4个季节的采样监测结果分析 (有效采样天数为 50d)得出 ,北京市细粒子质量浓度年平均值已超过美国国家标准的 7倍以上。研究发现细粒子的质量浓度不仅与环境条件有关 ,而且与气象条件也有着密切的关系。文中以细粒子的观测数据为基础 ,结合当时的气象条件进行细粒子浓度与气象条件定量关系的研究     

新藏公路新疆段多年冻土特征及其灾害初探

新藏公路新疆段沿线海拔高，气候干冷，第四纪松散堆积层厚，在高山区和山原河谷盆地区发育了多年冻土。勘查研究表明：多年冻土分布于K306 000～K310 000和K515 000～K705 00间191．6km路段上，属高原片状连续多年冻土。沿线个别路段含冰量较高，为多冰-富冰冻土，中冻胀中融沉；绝大部分路段以少冰多年冻土为主，弱冻胀弱融沉。现有公路主要冻土灾害有涎流冰、路基融沉、路面翻浆、冻胀破坏、冻融滑塌和冻融泥流等。随着整治改建工程的实施，多年冻土原有的水热平衡的破坏，冻土灾害将趋于严重。根据沿线多年冻土的特征，提出施工和运营中应采取保护冻土的设计原则，通过改线避绕、抬高路基、提高路基强度及完善截排水系统等5条措施以减少公路工程对多年冻土的扰动和破坏。     

安徽铜陵矿集区与块状硫化物矿床有关的热水沉积岩

通过对铜陵地区系统的填图观察和室内研究 ,初步确定了铜陵地区海西期的热水沉积岩。它们是 :石炭系黄龙组 ,由下而上、由内到外的层序包括含硫化物滑石蛇纹石岩 (由原岩为含水富镁碳酸盐岩 +二氧化硅的热水沉积岩变质而成 )→块状、层状 (含铜金 )黄铁矿±铁碧玉±硬石膏±菱铁矿±菱锰矿±硅质岩→含炭质粘土→白云岩 ;二叠系为栖霞组 (含铅锌金 )硅质岩、孤峰组 (含锰 )硅质岩和大隆组 (含钼 )硅质岩。这些热水沉积岩总体构成铜陵地区晚古生代多期热水活动的格局。常量元素、微量元素和稀土元素的分析结果表明 ,本区的硅质岩具有热水沉积岩的特征。氧同位素估算的热水硅质岩古温度在 4 9℃以上。铜陵地区的热水沉积岩对层控矿床的勘查和隐伏矿床的预测评价具有重要的理论和实际意义 ,尤其是黄龙组底部的热水沉积岩是铜陵地区找矿的重要标志 ,对于指导长江中下游地区 ,如宁芜等地 ,寻找该层位的矿床有着不可替代的指示意义。     

安徽铜陵朝山金矿床稳定同位素、稀土元素地球化学研究

朝山金矿床位于安徽铜陵狮子山矿田，属于矽卡岩型金矿床，侵入岩体为白芒山辉石二长闪长岩体。成矿过程包括矽卡岩阶段、石英-硫化物阶段和碳酸盐阶段3个主要成矿阶段。文章通过对朝山金矿床的氢、氧、碳、硫、硅同位素组成和稀土元素地球化学特征的研究，探讨成矿溶液中水、碳、硅和硫的来源以及成矿溶液的演化问题。研究表明，成矿热液早期以岩浆热液为主，随着成矿过程的进行，加入的大气降水比重越来越大，到晚期可能主要以大气降水为主。该矿床矿石中方解石的碳、氧同位素组成与矿区大理岩的碳、氧同位素组成明显不同，其δ^13 Cv-PDB、δ^18OV-SMOW值分别为-4．5～-5．3‰、13．9～14．0‰，与岩浆作用形成的CO2的碳、氧同位素组成一致，表明矿石中方解石的碳、氧来源于岩浆作用。硅和硫具深部岩浆或岩浆热液来源的特点。