Case study: a 3D resistivity and induced polarization imaging from downstream a waste disposal site in Brazil

A contaminated site from a downstream municipal solid waste disposal site in Brazil was investigated by using a 3D resistivity and induced polarization (IP) imaging technique. This investigation purpose was to detect and delineate contamination plume produced by wastes. The area was selected based on previous geophysical investigations, and chemical analyses carried out in the site, indicating the presence of a contamination plume in the area. Resistivity model has successfully imaged waste presence (ρ < 20 Ωm), water table depth, and groundwater flow direction. A conductive anomaly (ρ < 20 Ωm) outside wastes placement was interpreted as a contamination plume. Chargeability model was also able to imaging waste presence (m > 31 mV/V), water table depth, and groundwater flow direction. A higher chargeability zone (m > 31 mV/V) outside wastes placement and following conductive anomaly was interpreted as a contamination plume. Normalized chargeability (MN = m/ρ) confirmed polarizable zone, which could be an effect of a salinity increase (contamination plume), and the clay presence in the environment.     

Electrical resistivity investigation of potential cavities underlying a proposed ash disposal area

Measurements of electrical resistivity anomalies using a Wenner electrode array in a profiling mode were conducted over a 105-acre area near Crystal River, Florida Analyzed results of collected data were used to determine the likelihood of subsurface solution cavities beneath a proposed ash disposal area “Sounding” measurements with electrode spacing values extending up to 100 feet and Lee electrode measurements were used to identify and locate specific anomaly maxima identified anomalies on the order of 200 chms-feet contrasted with expected values of 300 to 400 ohms-feet and were attributed to lower resistivities inherent in water-filled solution cavities below a shallow water table Prominent cavity complexes at 5 to 15 feet depth were predicted in areas of low resistivity anomalies in the otherwise geoelectrically uniform, Eocene Ocala limestone Shallow test borings confirmed the presence of a significant concentration of shallow cavities in the predicted areas This study demonstrated the feasibility of electrical resistivity measurements as a reconnaissance tool to economically determine subsurface cavities and to aid in developmental and environmental planning     

高密度电法在某垃圾焚烧环保发电站岩溶c场地勘察中的应用

岩溶是某垃圾焚烧环保发电站场场址勘察的主要不良地质作用,为了查明岩溶和破碎带的分布情况,本文利用高密度电阻率法来探测能引起低阻异常的岩溶等地质体。在调查该区地层和溶洞的类型、分布及电性特征的基础上,利用RES2Dmod建立包含不同规模和埋深的低阻溶洞或破碎带模型,通过对比模型的温纳、偶极和微分三种装置类型的正反演结果,在本地区选用分辨率和稳定性高的温纳装置进行高密度勘测。利用高密度电阻率法查明了两个落水洞的埋深和分布情况,推测了4个疑似溶洞和破碎带,部分与后期验证钻孔吻合。利用合适的装置类型进行高密度探测可以查明充水充泥低阻溶洞的规模及分布,是一种经济有效的场址勘察方法。     

电阻率法和激发极化法在地下水勘查中的应用

依据提供的物性参数的不同,广泛应用于找水工作的电法手段可分为电阻率法和激发极化法两大类,其中电阻率法提供电阻率参数,主要解决与赋水有关的构造问题(如赋水层位或断裂构造)。方法上有常规电法、电磁法,可根据地区赋水部位的不同选择适当的方法。激发极化法则利用含水层的激发极化效应进一步确定目标层位或构造的赋水性。电阻率法和激发极化法相互配合,在找水工作中相得益彰。     

高密度电阻率法在勘察黄土洞穴及岩溶中的装置适用性研究

为了探究高密度电阻率法各种装置的适用性,基于有限差分法进行高密度电阻率法二级排列、三级排列、温纳装置、偶极装置、微分装置、偶极—偶极装置、斯伦贝谢装置等7种装置高、低阻异常体正演模拟.通过模拟结果可以看出,偶极装置对于低阻异常体和高阻异常体的探测效果均比较好,温纳装置仅适用于高阻异常体的探测以及高低阻异常体分界面的划分,其他装置模拟得到的高、低阻异常体的形态或位置与实际情况有一定偏差.将模拟结果运用于黄土洞穴、岩溶勘察中,取得了较好的探测效果,可供类似工区参考使用.     

激电测深在延安地区浅层地下水调查评价中的应用

延安地区地处陕北黄土高原丘陵沟壑区,属于干旱半干旱区,水资源相当缺乏,因此地下水调查的工作对延安有着重要的意义。本次在延安市区及周边地区进行了地球物理勘查工作,目的是研究延安地区地下300m以浅的地层岩性结构,为区域间接寻找浅层地下水提供基础物探成果。通过专家论证和前期试验,勘查工作采用激电等比测深装置,在对地电结构进行划分时,注重结合水文地质资料对测深点曲线类型进行分析和总结,使激电测深成果在延安地区浅层地下水调查评价的应用中取得了良好的应用效果。     

MapGIS在东天山高放废物地质处置库选址中的应用

根据高放废物选址的要求,利用MapGIS对东天山地区不同时代岩体的空间位置、分布形态、出露面积,以及岩体与断裂构造、地震和矿床点等的空间关系进行了研究,对海量资料信息进行分析处理,可起到事倍功半的效果。利用MapGIS分析结果,初步筛选出阿奇山1号岩体、雅满苏北岩体作为高放废物地质处置库选址的有利岩体。     

激发极化法在冰湖沟金矿区找矿中的应用

冰湖沟金矿区岩浆活动频繁、构造较为发育,区内有Ⅴ号角砾岩等赋矿岩体.角砾岩体矿化规模大,离矿体越近,矿化蚀变越强.标本测定表明,角砾岩体矿化蚀变后极化率显著增大,因此本区具有开展激电找矿工作的物性基础.在该区开展的激电工作成果得到了钻孔验证,指导了该区的地质找矿工作.     

大功率激发极化法在内蒙古马戈山南多金属矿区找矿中的应用

内蒙古东乌珠穆沁旗地区处于我国北方的一条重要成矿带上,但是在深部找矿方面没有新的突破.文章主要是对马戈山南地区多金属勘查中大功率激发极化法的应用进行总结.通过激电测深、激电中梯剖面测量,找出测量异常区进行合理解释后,指导勘探工程设计、圈定找矿远景区.以期能对相关区域的多金属勘查有一定参考和指导意义.     

Isotopic identification of the source of methane in subsurface sediments of an area surrounded by waste disposal facilities

The major source of methane (CH₄) in subsurface sediments on the property of a former hazardous waste treatment facility was determined using isotopic analyses measured on CH₄ and associated groundwater. The site, located on an earthen pier built into a shallow wetland lake, has had a history of waste disposal practices and is surrounded by landfills and other waste management facilities. Concentrations of CH₄ up to 70% were found in the headspace gases of several piezometers screened at 3 different depths (ranging from 8 to 17 m) in lacustrine and glacial till deposits. Possible sources of the CH₄ included a nearby landfill, organic wastes from previous impoundments and microbial gas derived from natural organic matter in the sediments.Isotopic analyses included δ¹³C, δD, ¹⁴C, and ³H on select CH₄ samples and δD and δ¹⁸O on groundwater samples. Methane from the deepest glacial till and intermediate lacustrine deposits had δ¹³C values from −79 to −82‰, typical of natural “drift gas” generated by microbial CO₂-reduction. The CH₄ from the shallow lacustrine deposits had δ¹³C values from −63 to −76‰, interpreted as a mixture between CH₄ generated by microbial fermentation and the CO₂-reduction processes within the subsurface sediments. The δD values of all the CH₄ samples were quite negative ranging from −272 to −299‰. Groundwater sampled from the deeper zones also showed quite negative δD values that explained the light δD observed for the CH₄. Radiocarbon analyses of the CH₄ showed decreasing ¹⁴C activity with depth, from a high of 58 pMC in the shallow sediments to 2 pMC in the deeper glacial till. The isotopic data indicated the majority of CH₄ detected in the till deposits of this site was microbial CH₄ generated from naturally buried organic matter within the subsurface sediments. However, the isotopic data of CH₄ from the shallow piezometers was more variable and the possibility of some mixing with oxidized landfill CH₄ could not be completely ruled out.     

Measurements of spectral induced polarization for environmental purposes

Hydraulic permeability is one of the most important parameters for the evaluation of sediments relevant to environmental and hydrogeological problems. Up to now, permeability could be determined only by time-consuming and expensive methods like pumping tests or sampling and laboratory investigations. The results are confined to few locations, and they depend on the scale of the investigation method. Measurements on rock samples in a laboratory can differ significantly from well test results. Geophysical measurements are performed on different scales from high resolution measurements in boreholes up to large-scale soundings. Variations in permeability are mainly caused by varying grain size and by changes in porosity. A decrease of average grain diameter results in an increasing internal surface area. Petrophysical investigations have shown a reliable correlation between the imaginary part of electrical conductivity and the porespace-related internal surface. The formation resistivity factor, which is related to porosity, can be determined by geoelectrical measurements if the electrical conductivity of the pore fluid is known. The internal surface area and the formation factor are the only two parameters used by a Kozeny-Carman-like equation to evaluate the permeability or hydraulic conductivity for the investigated representative volume. Complex electrical conductivity is determined by measurements of induced polarization in the frequency domain. Frequencies below 10 Hz are used to avoid electromagnetic coupling. The permeability values determined by electrical measurements in boreholes can well be compared with those derived from the grain size distribution of samples. The same algorithm can be applied to evaluate the hydraulic conductivity of subsurface layers by complex resistivity soundings. The high sensitivity of the imaginary conductivity component to changes at the internal surface may be used as an indicator for contaminations.     

低电阻率差情况下三维激电法快速数值模拟

将一种快速数值模拟方法用于激电法正演模拟中,利用在低电阻率差情况下,积分方程法模拟时阻抗矩阵的非对角线项可忽略,而只需计算矩阵主对角值这一关键点。这里详细阐明了三维地电断面激电法快速模拟方法,推导了求解过程,并以此为基础编制了计算程序。实例试算结果说明,该模拟方法在计算速度、计算精度上都收到了较满意的结果。     

Application of integrated methods in mapping waste disposal areas

An integrated suite of environmental methods was used to characterize the hydrogeological, geological and tectonic regime of the largest waste disposal landfill of Crete Island, the Fodele municipal solid waste site (MSW), to determine the geometry of the landfill (depth and spatial extent of electrically conductive anomalies), to define the anisotropy caused by bedrock fabric fractures and to locate potential zones of electrically conductive contamination. A combination of geophysical methods and chemical analysis was implemented for the characterization and management of the landfill. Five different types of geophysical surveys were performed: (1) 2D electrical resistance tomography (ERT), (2) electromagnetic measurements using very low frequencies (VLF), (3) electromagnetic conductivity (EM31), (4) seismic refraction measurements (SR), and (5) ambient noise measurements (HVSR). The above geophysical methods were used with the aim of studying the subsurface properties of the landfill and to define the exact geometrical characteristics of the site under investigation.     

浅谈激电中梯在吉林和安河金矿区的应用效果

通过对吉林省和龙市和安和金矿区的激电中梯的(视电阻率、视极化率)异常分析,结合区内地质条件,认为视极化率异常对指导该区进一步工作具有一定意义。     

高密度电法在新疆某矿区滑坡勘察中的应用

高密度电法集电测深和电剖面装置于一体,具有观测精度高、数据采集量大、地质信息丰富、生产效率高,以及探测深度较大等特点,在工程地质和水文地质勘查中被广泛应用。这里将高密度电法应用于新疆某矿区的滑坡体调查中,通过该矿区的地质地球物理特征,验证了实施高密度电法调查滑坡体的可行性。采用温纳装置,对矿区内的地层结构、滑床位置及深部地层情况的分析解释,证实了高密度电法应用效果良好,为进一步认识滑坡及其勘察治理提供了地球物理依据。     

Evaluating the risk of climate change to nuclear waste disposal

A hierarchy of models is being developed to represent the changes in climate that could occur in the next 10,000 years at proposed nuclear waste repository sites in the U.S. Three levels of modeling of the global aspects of climate change are included. At the broadest level a multitude of theoretical representations are being considered, most based upon the Milankovitch theory. A set of at least 150 situations will be examined, and those of concern for site stability will be screened for more thorough analysis at the next level of detail. The screening criteria include estimation of the probability of the event; the level of probability which must be considered (0.0001) requires use of the most detailed paleoclimatic records available. Uncertainty in the results will be evaluated by comparison of model reconstructions to the paleoclimatic record and by Monte Carlo analyses.This paper was presented at Emerging Concept, MGUS-87 Conference, Redwood City, California, 13–15 April 1987.     

高分辨地电阻率法探查小窑采空区的应用效果

介绍了利用高分辨地电阻率法探查大柳塔煤矿小窑采空区的作业方法和效果.钻探验证表明,这种探查方法可靠,所推断的采空区位置准确.这一探查结果为地面注浆灭火措施提供了科学依据.     

大功率激电法在河北槽碾沟地区深部找矿中的应用

在充分研究工作区地质、地球物理特征的前提下,采用大功率激发极化中梯剖面和激发极化测深相结合的方法进行勘查,发现了低阻高极化异常,推断深部存在矿（化）体。依据物探资料布设了验证钻孔,见到了铀钼共生矿体,证实了推断的正确性。     

三维高密度电法用于工程勘查的试验

国内三维高密度电法在工程上的应用,大都采用二维数据反演,通过三维成图软件把视电阻率剖面连成三维视电阻率分布立体图,而很少将三维数据拼接在一起,通过三维软件反演。结合管线探测,对真三维高密度电法进行了探测试验,并取得了良好的勘探效果,为三维高密度电阻率法的进一步推广提供了宝贵的实践经验。