Remediation and restoration of metal-contaminated sites： Concepts and appfications to mining areas     

Domy C. Adriano Hyo T. Chon Sally L. Brown Rosanna Ginocchio 《中国地球化学学报》2006,25(B08):45-46

Metals, including heavy metals and metalloids, are a common group of environmental contaminants. Their sources in the environment are geogenic or anthropogenic. The growing trend in global industrialization ensures that more metals could be dispersed even in pristine ecosystems. To fuel industrialization, more metal ore mines have to be discovered and explored. These explorations often result in landscape disturbance, soil degradation and environmental contamination by unwanted mining constituents. Mine tailings brought up to the ground surface often serve as the main source of contaminants when these pyrite-rich materials oxidize. The oxidation of mine tailings results in proton generation, coupled with the dissolution of metals and other cations Unwanted anionic constituents are also produced. The so-called ＂acid mine drainage＂ may affect the productivity of farmlands and stability of receiving streams and other bodies of water-acidifying the waters and enriching the ecosystem with metals, i.e., high total dissolved solids. The acidified overburden materials become inhospitable to plant and microbial life as they are typically low in organic matter content and infertile. This exposes the landscape to runoff and erosion.  相似文献   

长沙某高边坡支护设计优化          下载免费PDF全文

李仲秋  隆威 《探矿工程》2006,33(10):35-37

结合长沙某高边坡支护工程实例，详细研究边坡岩土条件及环境条件，充分挖掘岩土参数潜力：≯耋翌睾；方綦建藉蓑术、经济对比分析，优选锚杆网格梁法进行边坡加固支护。实践表明，锚杆网格梁法是一种加固高边坡性价比很好的方法。  相似文献   

Optimization of nonconventional wells under uncertainty using statistical proxies     

Vincent Artus  Louis J. Durlofsky  Jérôme Onwunalu  Khalid Aziz 《Computational Geosciences》2006,10(4):389-404

The determination of the optimal type and placement of a nonconventional well in a heterogeneous reservoir represents a challenging optimization problem. This determination is significantly more complicated if uncertainty in the reservoir geology is included in the optimization. In this study, a genetic algorithm is applied to optimize the deployment of nonconventional wells. Geological uncertainty is accounted for by optimizing over multiple reservoir models (realizations) subject to a prescribed risk attitude. To reduce the excessive computational requirements of the base method, a new statistical proxy (which provides fast estimates of the objective function) based on cluster analysis is introduced into the optimization process. This proxy provides an estimate of the cumulative distribution function (CDF) of the scenario performance, which enables the quantification of proxy uncertainty. Knowledge of the proxy-based performance estimate in conjunction with the proxy CDF enables the systematic selection of the most appropriate scenarios for full simulation. Application of the overall method for the optimization of monobore and dual-lateral well placement demonstrates the performance of the hybrid optimization procedure. Specifically, it is shown that by simulating only 10% or 20% of the scenarios (as determined by application of the proxy), optimization results very close to those achieved by simulating all cases are obtained.  相似文献   

阻燃级氢氧化镁制备过程中表面有机化改性   总被引：7，自引：0，他引：7       下载免费PDF全文

李晓崑  陈建军  孙海霞  关云山  王爱丽 《盐湖研究》2006,14(1):60-65

文章通过论述阻燃剂型氢氧化镁制备过程中的表面有机化改性,对改性剂、作用机理和改性工艺等进行了探讨,说明了对阻燃剂型氢氧化镁表面有机化改性的重要性,及在氢氧化镁制备过程中综合分析、系统研究的必要性。  相似文献   

Attenuation of aqueous metal transport at two natural acid rock drainage occurrences in the Yukon Territory, Canada     

Y.T. John Kwong 《中国地球化学学报》2006,25(B08):229-230

Naturally acidic drainage associated with pyritic black shale has been observed in many locations in the Yukon Territory. While not necessarily linked to known mineral deposits, most of these natural acid rock drainage occurrences show elevated dissolved concentrations of trace elements, especially zinc, nickel, copper, cadmium and arsenic. Based on field observations, microbial investigation, chemical analyses and geochemical modeling, the fate and transport of potentially deleterious elements at two natural acid drainage occurrences with slightly different settings are examined. The Macintosh Creek is a small, acidic stream （pH 2.98-3.40）, 2 km long, located in the Macmillan Pass area of east-central Yukon amidst known sedimentary exhalative massive sulfide mineralization but remains undisturbed by exploration activities. Its trace metal content is apparently derived from groundwater discharges, which gave as much as 5.0, 2.5, 0.7, 0.13 and 0.03 mg/L ofZn, Ni, Cu and As, respectively. Interaction and sorption reactions with algal mats, biofilms and iron oxyhydroxides appear to be the dominant mechanisms attenuating aqueous contaminant transport along the stream. Cryogenic precipitation further consolidates the ferricrete formation and reduces the mobility of the sorbed metals. The tributaries of the Engineering Creek along the Dempster Highway in northern Yukon drain through a series of dolomite, phyllite, argillite, limestone, black shale, sandstone and conglomerate with no known concentration of mineralization. In this area, the water chemistry fully reflects the local geology with acidic streams invariably associated with black shale occurrences. Groundwater seeps in the headwaters area of the km-180 Creek completely enclosed in black shale gave pH 3.0 and as much as 148, 39, 2.9 and 9.1 mg/L of Zn, Ni, Cu and As, respectively. Sorption with iron oxyhydroxide and organic matter appear to dominate the attenuation of contaminant transport along the stream. However, once entered into carbonate-dominated terrains, secondary carbonate minerals exercise additional geochemical control on the local water chemistry as a result of neutralization.  相似文献   

In situ time resolved synchrotron powder diffraction study of thaumasite     

Annalisa Martucci  Giuseppe Cruciani 《Physics and Chemistry of Minerals》2006,33(10):723-731

Structural changes during dehydration and subsequent decomposition in thaumasite Ca₃Si(SO₄)(CO₃)(OH)₆·12 H₂O were studied by in situ synchrotron powder diffraction between 303 and 1,098 K. Evolution of the crystal structure was observed through 28 structure refinements, by full profile Rietveld analysis performed in the P6₃ space group, between 300 and 417 K, whereupon the thaumasite structure was observed to breakdown. Within this temperature range, the cell parameters of thaumasite increased as a function of temperature in a nearly linear fashion up to about 393 K, at which temperature, a slight slope change was observed. Above 400 K, the thermogravimetric analysis revealed that the dehydration process proceeded very rapidly while the refined occupancy of water molecules dropped below a critical level, leading to instability in the thaumasite structure. At a same time, a remarkable change in the unit cell parameters occurring at about 417 K indicated that the crystal structure of thaumasite collapsed on losing the crystallization water and it turned amorphous. This result indicated that the dehydration/decomposition of thaumasite was induced by the departure of the crystallization water. At about 950 K, anhydrite and cristobalite crystallized from the thaumasite glass.  相似文献   

A Connectivity Index for Discrete Fracture Networks     

C. Xu  P. A. Dowd  K. V. Mardia  R. J. Fowell 《Mathematical Geology》2006,38(5):611-634

Connectivity is an important measure for assessing flow transport in rock, especially through fractures. In this paper, rock fracture systems are modelled by a discrete fracture model simulated by a marked point process. A connectivity index is then introduced to quantify the connectivity between any two points in space. Monte Carlo simulation is used to evaluate the connectivity index for stationary cases and relationships between the connectivity index and the parameters of the discrete fracture model are analysed. The average number of intersections per fracture, X_f, and the fracture intensity, P12 (P32), are calculated and the relationships between these parameters and the connectivity index are investigated, concluding that X_f is the more suitable parameter for the classification of rock mass flow properties. The relationships between the connectivity index and the percolation state of the fractured medium are also discussed. An edge correction is briefly discussed and a practical example is used to demonstrate the method of computing the connectivity index.  相似文献   

长春市强冰雪冻害天气系统及物理量特征     

汪秀清  杨雪艳  陈长胜  吴宪军 《地理科学》2006,26(3):364-368

应用1971~2000年长春气象站10月至次年3月的逐日降水量、气温资料以及相应的NCEP/NCAR再分析资料,通过对资料的统计分析,给出了确定长春市发生强冰雪冻害天气的标准;根据对36个历史个例的高低空环流形势的分析,建立了4种强冰雪冻害的天气概念模型:冷涡型、深槽型、浅槽型、锋区平直型;进一步分析了长春市冰雪冻害天气的物理量场、要素场的特征。  相似文献   

基于夜间灯光数据的环渤海地区城市化空间模式和过程研究     

何春阳  李景刚  陈婧  SHI Peijun  CHEN Jin  PAN Yaozhong  LI Jing  ZHUO Li 《地理学报(英文版)》2006,16(2):174-182

1 Introduction Urban agglomeration is a system of cities, supporting by the modern transportation and information network in the system, these cities, with different characteristics, types, sizes and hierarchies, interact with each other, and one or two …  相似文献   

全球及区域模式中陆面过程的地表植被覆盖分类方法   总被引：1，自引：0，他引：1  

姚凤梅  张佳华 《干旱区地理》2006,29(6):872-877

全球和区域尺度上陆面生态系统与气候密切相关。全球和区域模式的发展对于我们认识气候与陆地生态的变化起到重要作用。在这些模型中，植被覆盖是影响大气-植被间热量、水分和CO2等交换的重要陆面参数。在分析了陆地植被覆盖分类原理基础上，介绍了目前全球不同植被覆盖分类方案，包括基于地基观测的植被分布、基于生物气候特征的分类方案（如：Holdridge的方案）；特别近年来陆面过程试验表明，各种遥感数据源（如：NOAA—AVHRR，EOS—MODIS，Landsat—TM）等为我们提供了有利的工具来监测全球植被动态，完善植被分类，并且采用高时空分辨率的全球土地覆盖状况特征，在不同时空尺度揭示植被-大气相互作用。本文分析了代表性的3种基于卫星遥感技术的陆面植被分类方案，分别是BATS（18类）、SIB（9类）、SIB2（12类）和BIOME—BGC（31类）陆地模式的植被覆盖分类方案．最后分析了目前可用于全球植被覆盖分类的新的遥感数据库。  相似文献