大别山北缘地质找矿中遥感方法的研究

本项工作着重探讨在植被覆盖、地质背景十分复杂的地区，利用遥感信息寻找金矿及其它多金属矿的方法。即从地层岩系、构造及构造交叉部位、蚀变带这三个方面，进行地质找矿专题信息特征提取方法的研究。最后，通过信息提取及影像综合特征，进行遥感地质制图，圈定找矿有希望的地段。     

基于地理信息系统的数字环境模型研究

本文提出了以遥感与地理信息系统为技术手段,用有序数值阵列的方法建立数字环境模型的新思路,具体阐述了建立数字环境模型的意义、方法和应用范围。并在建立数字环境模型的基础上,对西藏“一江两河”地区的环境综合状况进行了定量评价。     

南秦岭金龙山微细浸染型金矿成矿时代

 金龙山金矿带是南秦岭新发现的卡林型金矿带,主要产于上泥盆统南羊山组细碎屑岩—碳酸盐岩建造中,在上泥盆统冷水河组、下石炭统碳酸盐建造中也有产出,可分为明显受断裂控制的脉型金矿化和受有利岩性及小规模断裂、节理控制的浸染型矿化。     

综论土壤呼吸各组分区分方法

研究土壤呼吸各个组分对土壤总呼吸的贡献是定量评价植物和土壤碳平衡及能量平衡的 重要基础。目前区分土壤有机质分解呼吸和根呼吸的方法主要有成分综合法、壕沟法、根分离法、 林隙法、根生物量外推法、同位素法, 区分纯根呼吸和根际微生物呼吸的方法有同位素稀释法、模 拟根际沉降物法、¹⁴CO₂ 动态法、根系分泌物洗涤法、δ¹³C 微生物量法及一些非同位素法的联合。 土壤呼吸各组分区分研究中, 区分纯根呼吸和根际微生物呼吸将是未来研究的一个重大课题, 区 分方法的改进、完善和创新, 不同区分方法间的比较研究将是未来研究的一个重要方向。     

Trends and risk evolution of drought disasters in Tibet Region,China

Journal of Geographical Sciences - The risk posed by natural disasters can be largely reflected by hazard and vulnerability. The analysis of long-term hazard series can reveal the mechanisms by...     

A statistical analysis applied to the Rf/φ method

A statistical analysis for the R_f/φ method is developed in the paper. The technique provides estimates of R_s, R_i and θ according to R_f and φ. Moreover, we can restore the pattern of initial orientations of marker objects by means of their frequency histogram, provided the strain is homogeneous. It is unnecessary to postulate random initial orientations if the principal directions of strain ellipsoid are known.     

Biofilms, microbial mats and microbe-particle interactions: electron microscope observations from diatomaceous sediments

Sediments and diatoms from the mudflats of the Bay of Bourgneuf in western France were examined in an electron microscope study of biofilms and microbial mats. The sediments were kept in an aquarium for study and a diatom culture was made of the benthic diatoms. The sediment biofilm was composed of exopolymeric substances (EPS), incorporated clay particles and, rarely, bacteria. This film coated all particles at the sediment-water interface. Its surface morphology reflected its composition and internal structure. Thin films were smooth, whilst a lumpy structure or incorporated fibrils produced either a mammillated or ropy surface, and clays in the structure gave rise to a flaky morphology. At shallow depths in the sediment column (0.5 cm) the biofilm was already degraded. The biofilm coating degraded diatom frustules in the benthic diatom culture consisted of EPS and bacteria and presented a ragged appearance. Microbial mats occurred on the surface of the fresh littoral sediments as well as those in the aquarium, and on the wall of the aquarium. The mat on the surface of the aquarium sediments had an open structure with webs of fibrils and bacteria in the pore space. It formed in a relatively quiet environment. Pore space was more limited in the mat from the surface of the fresh littoral sediments, in which direct contact between biofilm coated particles was common. In the exposed environment of the aquarium wall there was a thick, resistant coating of EPS. In addition to binding particles together, the presence of mats and biofilms in sediments affects sediment physical properties such as porosity and permeability, the flux of dissolved substances in pore waters and the dissolution of particles and can, therefore, influence early diagenesis. Mats and biofilms seem to be more readily preserved in the geological record than the micro-organisms, such as bacteria, which produce them. Their identification in the sedimentary record would greatly aid interpretation of sediment genesis and evaluation of the microbial role in sediment formation.     

Combined perturbation on near-earth satellite orbits

Using a semi-analytical method, we have obtained a first-order solution of the equations of motion of near-Earth satellites under the combined perturbing effect due to Earth's figure and air drag.