南极无冰区典型沉积环境石英砂表面结构特征及其在沉积环境识别中的应用

本文利用电镜扫描方法 (SEM)对比分析了南极乔治王岛无冰区海滩沉积、冰碛物以及阿德雷岛湖泊沉积等典型沉积环境中的石英砂表面结构特征 ,得出了乔治王岛各典型沉积环境中石英砂表面结构特征的颗粒频率曲线。结果表明 :不同沉积环境下的石英砂颗粒表面结构特征具有相似性 ,这主要和南极地区广泛发育的冰川作用有关 ,同时 ,它们也有各自典型的特征组合 ,这些典型特征组合的不同反映了石英砂后期的搬运历史和沉积环境的差异。本文还依据石英砂表面特征的颗粒出现频率 ,利用聚类分析方法对研究区内三级海岸阶地上的沉积物和一个未知成因的样品进行了沉积环境的判别分析 ,结果证明石英砂微形貌特征可以作为南极地区沉积环境识别的有效手段     

Microclimate, freezing tolerance, and cold acclimation along an elevation gradient for seedlings of the Great Basin Desert shrub, Artemisia tridentata

Vegetation, microclimate, seedling frequency, freezing tolerance, and cold acclimation were compared for seedlings of Artemisia tridentata collected from 1775, 2175, and 2575 m elevation in the eastern Sierra Nevada, California. Data were used to test the hypothesis that ecotypic differences in stress physiology are important for seedling survival along gradients from desert to montane ecosystems. The vegetation canopy cover and A. tridentata seedling frequency were greatest at 2575 m, compared to 1775 and 2175 m. Snow cover ameliorated temperatures near the soil surface for part of the winter and depth varied across elevations. Freezing tolerance was compared for seedlings maintained in growth chambers at day/night air temperatures of 25°C/15°C. The temperature at which electrolyte leakage and Photosystem II function (F_V/F_M) from leaves were half-maximum was approximately −13·5°C for leaves of seedlings from all three elevations. Shifting day/night air temperatures from 25°C/15°C to 15°C/5°C initiated about 1·5° of acclimation by plants from all three altitudes, with seedlings from the highest elevation exhibiting the greatest acclimation change. Measurements of ambient air and canopy temperatures at the three elevations indicated that wintertime average low temperatures were consistent with the measured degree of freezing tolerance. At small spatial scales used in this study, pollen and seed dispersal between study sites may have precluded resolution of ecotypic differences. Patterns of freezing tolerance and cold acclimation may depend on a combination of mesoclimate and microclimate temperatures, canopy cover, snow depth, and snow melt patterns.     

不对称抽道集共反射面元叠加方法探讨

总结不对称抽道集共反射面元叠加方法的工作经验，提出自由观测面自由反射界面不对称抽道集共反射面元叠加方法的处理思路和计算方法。在自由观测面的条件下，反射界面可分为简单倾斜平面、规则曲面和自由反射界面三种情况，针对不同情况讨论共反射面元的叠加方法。综合一般情况下的共反射面元叠加方法，提出了“鳞片法”的处理思路。     

论桩基施工中流砂现象处理

地下水流动对土体产生渗透力；当渗透力大于土体的抗剪强度，土体破坏，也就是当施工造成地下水水力坡度超过砂层的临界水力坡度即产生流砂现象．运用水文地质工程地质学方面的原理其处理方法有两类：—是莫尔一库仑法：即c法和φ法；二是临界水力坡度法(Ic法)．     

几种常见矿物的接触角测定及其讨论

为了评价矿物表面与特征液体的界面能量，分别测定了长石、石英、黑云母、方解石、萤石和黄铁矿等7种常见矿物与水、正庚烷和正丁醇的接触角，并计算了相应的表面自由能。结果表明同一矿物不同结晶面(晶面)的接触角有一定的差异，这一差异与矿物结构面上原子种类和相对含量差异有一定的对应关系。     

梯度法在水文地质参数估值中的应用

根据地下水的抽水试验求含水层的导水系数和储水系数时,传统的计算方法是配线法和直线图解法。这两种方法比较繁琐,且人为误差较大。本文运用数学模型的最优化方法即梯度法,并借助于计算机编程,实现了水文地质参数的数值求解。计算结果能消除人为误差,准确反映含水层的参数特征。     

海洋天然气水合物的地球物理研究(III):似海底反射

对天然气水合物研究中与似海底反射有关的一些观点进行讨论 ,以推动天然气水合物地震研究的认识 .30年的似海底反射研究表明 ,似海底反射仍然是指示天然气水合物沉积存在的最好手段之一 .有似海底反射 ,是可以认为存在天然气水合物的 .虽然存在“游离气带速度模型”与“水合物楔速度模型” ,但似海底反射主要由天然气水合物稳定带底界下方的游离气引起 .BSR上方的天然气水合物、下方的游离气与天然气再循环和含甲烷的流体流有关 .由于天然气水合物稳定带计算控制因素难以准确确定等因素 ,似海底反射与天然气水合物稳定带底界只是近似的对应关系 .需从动态的观点考虑天然气水合物 天然气体系及其与似海底反射的关系 .     

慕士塔格峰洋布拉克冰川消融的观测分析

2001年7月4日至8月8日,在慕士塔格峰西侧的洋布拉克冰川海拔4600～4460m区间的冰舌段,进行了短期的冰面消融观测.慕士塔格峰冰川区暖期短,冰面强消融时期比较集中.观测期间,冰面纯消融厚度为640～1260mm水层,日平均消融厚度达26～39.6mm,推算冰舌区年消融量不低于1700～2000mm,比青藏高原内部的冰川消融强烈的多.7月21-22日出现最大消融值,在海拔4460m和4600m,日消融量分别为144.5mm和59.5mm.冰面消融随海拔上升而减小,日平均消融梯度:在裸露冰区为0.40～0.55mm·10m-1;在表碛覆盖区为0.21～3.53mm·10m-1,变幅较裸露冰区大.按裸露冰区的消融梯度计算出海拔4800m处的日平均消融量,和过去的研究资料比较,2001年冰面日平均消融量较1987年和1960年的消融量大,反映出慕士塔格峰区影响冰川消融的气候与全球气候变暖的特点是一致的.     

高精度推求正高的两种方法

论述了高精度推求正高的两种方法 ,并对正高精度的推估及其在模型上的试算也作了讨论 ,对于海拔为 5 0 0 0m的高山 ,正高的误差一般不超过± 1 0cm ,这与距青岛水准原点达数千公里的西部高山 (原 )处正常高的精度也比较接近     

An experimental investigation of LNAPL migration in an unsaturated/saturated sand

Accidental spills of hydrocarbons, such as Light Non-Aqueous Phase Liquids (LNAPLs), are one of the most common sources of subsurface contamination. Migration of LNAPL in a porous medium is influenced by various factors such as the number of fluids present in the unsaturated/saturated zones and the proportion of pores occupied by each fluid. The results for relationship between matric suction and degree of saturation are presented in this paper for water–air, water–LNAPL and LNAPL–air systems in a sand. A simple and reliable setup using Buchner funnel was designed to obtain these relations. It was found that the relationship between matric suction head and degree of saturation is hysteretic for all the fluid systems (water–air, water–LNAPL and LNAPL–air). Furthermore, the amount of hysteresis depended upon the fluid system, with the maximum hysteresis occurring for water–air system. The results suggest that the amount of trapped air depends upon the reversal degree of saturation from drying to wetting.