聚类分析在地下水水质分类评价中的应用

为更好的探究聚类分析在地下水环境评价中的应用,结合重庆市藻渡水库工程,采用系统聚类法分析了水库枢纽和库区位置的地下水监测点与周围煤矿污染源之间的相互关系,运用灰色聚类法和改进的灰色聚类法对地下水监测点进行综合评价,并分析了两种方法的优缺点。最终将17个地下水监测点划分为未超标天然地下水和受煤矿开采污染的地下水两大类,分析了污染物来源并评价了污染程度,为藻渡水库工程的地下水污染防治提供了科学依据。     

Magnetic and ground probing radar measurements for soil pollution mapping in the industrial area of Val Basento (Basilicata Region, Southern Italy): a case study

The joint application of electromagnetic techniques for near-surface exploration is a useful tool for soil pollution monitoring and can also contribute towards describing the spatial distribution of pollutants. The results of a geophysical field survey that was carried out for characterizing the heavy metal and waste disposal soil pollution phenomena in the industrial area of Val Basento (Basilicata region, Southern Italy) are presented here. First, topsoil magnetic susceptibility measurements have been carried out for defining the spatial distribution of superficial pollution phenomena in the investigated area. Second, detailed and integrated measurements based on a high-resolution magnetic mapping and ground probing radar (GPR) profiling have been applied to investigate the subsurface in two industrial areas located in more polluted sites that were identified during the first phase. Our monitoring strategy discloses the way to rapidly define the zone characterized by high pollution levels deriving from chemical industries and traffic emissions and to obtain the way information about the presence of local buried sources of contamination.     

大气环境中汞污染的研究进展

总结了大气环境中汞污染的研究进展，包括大气环境中汞的来源、汞在大气环境中的化学演化和环境效应；介绍运用环境地球物理方法在大气颗粒汞研究的初步结果，并就我国汞污染研究提出有关建议。     

Pollution pattern of underground river in karst area of the Southwest China

Investigation of groundwater pollution has been carried out on multiple typical karst underground river systems in recent years in order to reveal the characteristics and mechanism of underground river pollution. Through the summary of the survey results, five characteristics of underground river pollution have been revealed, including directionality, weak hysteresis, easier for reversibility, linear and intermittent (or seasonal); combining with karst geomorphic types, pollution sources (primordial, secondary pollution and compound), pollution ways and pollution receptors, three basic pollution patterns of the underground river were depicted: Recharge area pollution, runoff area pollution and discharge area pollution. At the same time, the study discloses the reality of the underground river pollution is the three basic patterns and their subgenera in combination with super imposition on the space and time. And from the angle of the hydrogeological model, the study expounds the process of underground river pollution. Finally, the study gives naming rules of pollution pattern of the underground river and sets up PISAB method of pattern recognition. The results provide scientific basis for pollution repair and management of underground river in the southwest karst region.     

南海东北部磁静区深部构造及成因模式

2001年7-8月,国家重点基础研究发展规划项目（973）的二级课题《中国边缘海前新生代基底特征及其构造格局》与两岸合作课题《南海东北部与台湾间的构造及地球物理研究》合作在南海东北部地区开展了重、磁、震资料的海上采集航次,获取了大量珍贵数据,其中973NH-01与MLTW测线垂直穿越了南海东北部传统意义上的磁静区。以这两条测线的重磁资料为主,结合地震解释剖面,对磁静区的重磁异常特征、重磁基底及深部构造进行了深入的分析和研究,并结合前人工作对磁静区的成因模式提出了新的解释,认为磁静区位于南海北部被动大陆边缘的洋陆交界带（COB）,独特的动力构造背景导致其下伏的地幔高热物质上涌并沿构造薄弱带侵入成岩墙,进而造成区域居里面抬升,磁性层减薄,磁异常减弱而形成磁静区。     

应用地球化学模式恢复准噶尔盆地东部浅层地下水的氧化-还原环境

地下水的ＥｈＷ值是反映其氧化还原能力的水文地球化学参数,是确定铀氧化还原环境必不可少的参数之一。在准噶尔盆地东部进行１∶５０万层间氧化带砂岩型铀矿床区调时,受工作条件限制,没能对所采集到的水样进行ＥｈＷ值测定,因而影响了对水的氧化还原能力的评价,但是这批水样分析资料中的Ｆｅ２＋／Ｆｅ３＋是非常有用的氧化还原电对,可用来模拟计算地下水环境的ＥｈＷ值。详细讨论了应用地球化学模式来模拟计算地下水ＥｈＷ值的原理和结果。     

Structural control of weathering processes within exhumed granitoids: Compartmentalisation of geophysical properties by faults and fractures

In the latter stages of exhumation processes, rocks undergo weathering. Weathering halos have been described in the vicinity of structures such as faults, veins or dykes, with a lateral size gradually narrowing with depth, symmetrically around the structures.In this paper, we describe the geophysical characterisation of such alteration patterns on two granitoid outcrops of the Catalan Coastal Ranges (Spain), each of which is affected by one major fault, as well as minor faults and fractures. Seismic, electric and ground penetrating radar surveys were carried out to map the spatial distribution of P-wave velocity, electrical resistivity and to identify reflectors of electromagnetic waves. The analysis of this multi-method and complementary dataset revealed that, at shallow depth, geophysical properties of the materials are compartmentalised and asymmetric with respect to major and subsidiary faults affecting the rock mass. This compartmentalisation and asymmetry both tend to attenuate with depth, whereas the effect of weathering is more symmetric with respect to the major structure of the outcrops. We interpret such compartmentalisation as resulting from the role of hydraulic and mechanical boundaries played by subsidiary faults, which tend to govern both the chemical and physical alterations involved in weathering. Thus, the smoothly narrowing halo model is not always accurate, as weathering halos can be strongly asymmetrical and present highly irregular contours delimiting sharp contrasts of geophysical properties.These results should be considered when investigating and modelling fluid storage and transfer in top crystalline rock settings for groundwater applications, hydrocarbon or geothermal reservoirs, as well as mineral deposits.     

A multidisciplinary approach for rock spreading and block sliding investigation in the north-western coast of Malta

Landslides are widespread along the north-western coast of the Island of Malta and are strictly linked to the structural setting. Exemplary cases of rock spreading and block sliding phenomena characterise this stretch of coast. They are favoured by the overposition of two different geological units widely outcropping there, the Blue Clay Formation and the Upper Coralline Limestone Formation. The latter forms a wide plateau, bordered by vertical cliffs. At the foot of the cliffs, clayey terrains crop out and develop gentle slopes covered by large blocks detached and moved by rock spreading and block sliding phenomena. These mass movements are favoured by the fragile behaviour of limestones, which cap clays, otherwise characterised by visco-plastic properties. In order to investigate the kinematics and the evolution of these types of coastal landslides, a multidisciplinary and multitechnical approach was applied on a study site, named Il-Prajjet, which provides a spectacular case of rock spreading evolving into block sliding. This paper illustrates the results achieved by means of different engineering geological and geophysical techniques allied with traditional detailed geomorphological survey and mapping. In particular, the surface displacements of the landslides were determined using long-term GPS observations, acquired approximately every 6 months, over a 4.5-year period. A network of GPS benchmarks were distributed on the edge of a limestone plateau affected by rock spreading and on a series of displaced blocks making up a large block slide, finally enabling the definition of the state of activity and the rates of movement to be performed. In addition, the results deriving from two continuous fissurimeters more recently installed at the edge of two persistent joints over the block sliding area are outlined, with reference to the correlation between variations of crack apertures and precipitation input. In order to identify main structural discontinuities and to reconstruct variability of underground surface contact between clays and overlying limestones, Resistivity Tomography profiles and GPR investigations were carried out. Finally, the results obtained by combining the outputs of geophysical surveys and different field monitoring activities can be considered a first step on which numerical models can be developed and validated, in order to assess landslide hazard and risk of this stretch of Maltese coastline.     

Mass transport modelling to assess contamination of a water supply well in Sabarmati river bed aquifer, Ahmedabad City, India

 Drinking water supply wells were constructed in the Sabarmati river bed aquifer of Ahmedabad city using radial pipes and are known as French Collector wells. Contamination of groundwater from one of the French wells near Sabarmati railway bridge was noticed in 1992. The suspected pollution sources are Duff-nala of Shahibaug and two other sources from slum dwellings on either side of Sabarmati river. A combined groundwater flow, pathlines and a mass transport model was constructed covering an area of 9 km² to analyse the capture zone of the French well under two different scenarios. Aquifer parameters of the river bed aquifer were available. Dry river bed condition was simulated under scenario I and controlled flow in the river bed was simulated under scenario II. The groundwater velocity and migration of contaminant particles from sources was analysed in the pathline model. Total dissolved solids (TDS) concentration contours originating from sources in the mass transport model (MT3D) were computed by solving an advection-dispersion equation. The computed pathlines and TDS concentration contours indicate likely migration of contaminant plume from pollutant sources to the French well during 365 days under two scenarios. The model results confirm the tracer injection studies carried out to know the likely migration of contaminants towards the French well. The modelling study emphasised the necessity of controlled release of surface water in Sabarmati river bed from Dharoi reservoir throughout the year. Received: 28 October 1998 · Accepted: 17 June 1999     

西藏铁格隆南铜(金)矿床三维模型分析与深部预测

铁格隆南铜(金)矿床是近年来在班公湖-怒江成矿带西段多龙矿集区新发现的超大型Cu(Au-Ag)矿床。本文针对铁格隆南矿区深部找矿问题,以现代成矿地质理论和多元地学信息综合分析技术为支撑,以构建矿床找矿模型为指导,依托数据库技术、3S技术、三维建模与可视化技术及地质统计学理论与方法,开展基于矿产地质、地球物理、地球化学等成矿条件及找矿标志的三维地质实体建模与矿化异常三维空间重构,将铁格隆南矿床的预测评价研究拓展到三维空间,揭示了区内成矿地质特征、地球化学及地球物理异常表征,据此探讨了矿床的成因及矿体分布特征。并在此基础上,开展了矿区的地质-地球化学-地球物理综合信息分析与预测评价,以期减少单一信息多解性和成矿条件不确定性,为铁格隆南矿区深部找矿工作提供参考。研究结果表明:在地质找矿模型指导下,基于深部成矿空间三维结构重构基础上的三维地质、地球物理、地球化学异常信息提取与综合分析,可以有效的识别成矿地质体和矿致异常信息,实现深部矿产资源靶区空间定位预测,为深部找矿预测研究提供了新思路。综合分析结果显示铁格隆南矿床深部找矿潜力巨大。     

Localization of water bearing fractured zones in a hard rock area using integrated geophysical techniques in Andhra Pradesh,India

Knowledge of the existence of fracture zones, their extent, intensity and direction is very useful for assessing groundwater in hardrock regions and in this context geophysical methods are widely accepted as a powerful means of study. In the modern era of exploration, application of the Resistivity Imaging technique gives a new opportunity for groundwater study in hardrock regions. Exploration surveys were conducted at one of the important sites in Maheshwaram watershed, Andhra Pradesh, India with a multielectrode resistivity imaging system. To reduce the ambiguity of geophysical interpretation some complementary geophysical studies like ground Magnetic and VLF were also carried out.A number of 2D resistivity images were prepared in a grid pattern, which clearly show the weathered and fractured zones in different parts of the study area. With the help of all 2D profiles a quasi-3D image has been created, which indicates the orientation and extension of the fracture zone in a horizontal as well as vertical direction in the study area. Strong agreement exists among the anomalies identified using the ground magnetic, VLF and resistivity imaging methods. The litholog data available in the study area also helps to interpret geophysical results to find a potential groundwater bearing zone in that area.     

Review of self-potential methods in hydrogeophysics

The self-potential (SP) method is a passive geophysical method based on the natural occurrence of electrical fields on the Earth's surface. Combined with other geophysical methods, SP surveys are especially useful for localizing and quantifying groundwater flows and pollutant plume spreading, and estimating pertinent hydraulic properties of aquifers (water table, hydraulic conductivity). Laboratory experiments have shown that the involved coupling coefficients mainly depend on the fluid chemistry, conductivity and pH, and on the soil or rock properties. The interpretation of SP observations can be done qualitatively, for instance, by correlation of SP gradients with water fluxes (through electrokinetics) or salt fluxes (through electro-diffusion). In recent years, the interpretation has been improved with the help of modelling or/and inversion of the Poisson equation and endeavours to estimate hydraulic parameters by means of the intensity of electric current sources caused by underground flows.     

工程物探方法在地质灾害评估中的应用

利用工程物探方法对济南市历城区全民健身中心建设项目铁矿采空区进行了勘查工作,结果表明物探电阻率测深法勘查工作,对铁矿采空区反映效果明显,结合磁测资料与现场调查访问,推测出评估区内的2处隐伏采空区影响范围基本与事实一致。     

王坡井田煤层气井部署方法研究

王坡煤矿是高瓦斯矿井,已有的井下瓦斯抽排不能满足矿井安全生产的要求,迫切需要通过地面抽采来缓解。在已有地质成果基础上,采用煤层气藏数值模拟方法,对王坡井田地面煤层气抽采工程部署方案进行优化。结果表明:A区块是井田煤层气开发试验首选区,以梅花形井网作为试验井网,井间距300m×250m,井网长轴方向60°。这种布井方式在工程实践中取得了较好效果,具有较大的推广价值。     

Use of solid phase characterisation and chemical modelling for assessing the behaviour of arsenic in contaminated soils

A soil, containing waste material from an industrially contaminated site, was found to be heavily contaminated with several heavy metals and As. A risk assessment for As leaching from this material has been carried out in several stages, collation and examination of historical records, solid-phase characterization and chemical modelling. The historical record indicates that the most probable source of As was arsenopyrite. However, the solid phase characterization of the soil, using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive microanalysis (EDAX), did not yield any direct evidence for pyritic phases, although there was clear evidence of known pyrite-weathering products, such as jarosite. The relative stability of pyrite and arsenopyrite have been modelled for the range of acidity and redox potentials likely to be encountered on the site. For adsorption modelling, a surface complexation model was used to predict arsenate desorption as a function of pH. It was assumed that the principal reactive adsorbent for As was hydrous ferric oxide (HFO) and this assumption was supported by the results of direct and indirect measurements and by the mineral stability calculations. This approach was successful at predicting the increased mobility of As at increasingly alkaline conditions. The modelling predictions were supported by results from batch equilibration experiments. Thus, it was possible to link direct observations of mineralogy, mineral stability calculations and adsorption models in order to predict the mobility of As. The success of this approach was dependent on identifying the reactive phase in this particular soil and having the appropriate data required for the adsorption modelling.     

招远市道头地区蓄水构造条件分析

以招远市道头地区作为研究区。本区位于低山丘陵地区,由于受自然条件限制,普遍存在缺水现象。本次根据前期调查结果,以区内的地质、水文地质条件为基础条件,采用多种地球物理勘探方法相结合的方法,同时依靠钻探、抽水试验等技术手段,将区内的蓄水构造类型共划分了侵入-接触型蓄水构造、接触型蓄水构造和隔水型蓄水构造三类。通过对不同蓄水构造的构造类型,围岩岩性,构造与围岩相互关系,地下水流向,构造隔水性质等地质、水文地质条件的分析确定靶区,结合地球物理勘探方法对靶区进行解译,根据解译结果最终确定井位,并在确定的井位点进行钻探施工和抽水试验,对其富水性进行验证。通过以上多方法结合最终提出了在该种地区中定井方法,提高了成井的成功率,为缺水地区找水提供了理论支撑和实用方法。     

激电法在西北某油田上的应用效果

本文依据前人的理论基础,在总结分析激电法找油的地球物理前提条件下,开展了该方法的试验兼生产工作,取得了令人满意的效果,并进一步证实了激电法找油的异常模式。     

激电法在西北某油田上的应用效果

本文依据前人的理论基础，在总结分析激电法找油的地球物理前提条件下，开展了该方法的试验兼生产工作，取得了令人满意的效果，并进一步证实了激电法找油的异常模式。     

Environmental applications of geophysical and geochemical methods to map groundwater quality at Tuticorin, Tamilnadu, India

Coastal aquifers can become polluted due to natural and human activities, such as intrusion of saline water, discharge of effluents in industrial areas and chemical weathering of natural geological deposits. The present study is aimed mainly at understanding the geophysical and chemical characteristics of groundwater near Tuticorin, Tamilnadu, India by studying the electrical resistivity distribution of the subsurface groundwater by applying the Schlumberger vertical electrical sounding (VES) technique followed by chemical analysis of water samples. A total of 20 VES soundings were carried out to understand the resistivity distribution of the area and 21 water samples were collected to analyze the chemical quality. The interpretation and analysis of the results have identified different hydrogeologic behaviors, a highly saline coastal aquifer and freshwater locations. The results obtained from geophysical and geochemical sampling are in good agreement with each other. The approach shows the efficacy of the combination of geophysical and geochemical methods to map groundwater contamination zones in the study area.     

Environmental impact and vulnerability of the surface and ground water system from municipal solid waste disposal site: Koshe, Addis Ababa

Geo-environmental assessment and geophysical investigations were carried out over the only functional municipal solid waste disposal site of the city of Addis Ababa, Ethiopia, known locally as Koshe. The accumulated wastes from Koshe have impact on the surrounding human and physical environment since the disposal site was not designed. The study deserves emphasis because the city of Addis Ababa currently obtains a considerable portion of its domestic water supply from a well field developed not much farther from and along a groundwater flow direction in relation to the waste disposal site. It was found out that the leachates from the site contain high concentration of biological oxygen demand, chemical oxygen demand, chloride and sulphate besides high concentration of cobalt, nickel and zinc in the surrounding soils. The geophysical results have mapped weak zones and near-vertical discontinuities that could potentially be conduits for the leachate from the wastes into the deep groundwater system. Further, a zone of potential leachate migration from the landfill was identified from the electrical models; the location of this zone is consistent with the predicted direction of groundwater flow across the site. The results further suggested that the open dump site tends to cause increasing amount of pollution on the surrounding soil, surface and ground waters. Furthermore, it was observed that the Koshe waste disposal site has grown beyond its capacity and the poor management of the open dump landfill has reduced the aesthetic value of the surrounding environments. The need to change/relocate the existing waste disposal site to a more suitable and technologically appropriate site is emphasized.