Comparison of approaches for the characterization of contamination at rural megasites

The present work focuses on approaches for the characterization of subsurface contamination, which need to be reliable and cost-effective, particularly for extended and remote areas aimed at being redeveloped. Requirements are discussed with respect to specific conditions at megasites, in order to enable site valorization. In a case study, two approaches are compared, comprising (1) conventional site investigation based on historical surveys and concentration measurements at monitoring wells installed in areas suspected of being polluted and (2) the use of direct push (DP) methods covering the complete area. The DP investigation provided information on the contamination distribution and yielded also important information on hydraulic conditions. Statistical analysis of the results applying indicator kriging revealed that the conventional approach is markedly risky when decision-making relies solely on historical and sparse data. The DP campaign remarkably reduced the uncertainty concerning the estimated occurrence of polluted groundwater at the whole site. Furthermore, monitoring measurements are analyzed showing the possible importance of temporal variability. Taking economical consideration into account, DP-based groundwater screening is recommended to obtain either first or complementary information on the entire site. Based on these data, also locations for a long-term monitoring could be selected if temporal variability is assumed relevant.     

Investigation of groundwater contamination using electric and electromagnetic methods at an open waste-disposal site: a case study from Isparta, Turkey

 Geophysical methods, when integrated with soil chemical and hydrogeological methods, can be used to investigate groundwater contamination. Direct current (DC) resistivity geo-electrical sounding and very-low-frequency electromagnetic (VLF-EM) data were collected at an open waste site used by the municipality of the city of Isparta, Turkey. The groundwater at shallow depths in alluvium, which is composed of gravel, sand and clay, were expected to be hazardously contaminated under and around the open waste-disposal site, in which both household and industrial wastes are known to be disposed of improperly. In this study, we mapped the spread of groundwater contamination using a VLF-EM method, which allows fast and inexpensive data collection. The method complements the results of geo-electrical sounding. There is a good correlation between the results of the VLF-EM and the DC-resistivity methods employed for the investigation of subsurface structure of the site, where soil chemical and previous hydrogeological surveys have indicated high levels of chemical concentrations. Received: 17 January 2000 · Accepted: 12 August 2000     

Use of a forensic geochemical technique and a hydrogeological assessment to determine the source of petroleum hydrocarbon contamination at a foreshore site in Korea

Investigations undertaken in 2013 at a foreshore site that was historically used for ship repairs in Korea indicated that soil and groundwater were contaminated with petroleum hydrocarbons over an area of 10,000 m². Groundwater investigations and modelling were undertaken to determine the characteristics of aquifers beneath the site, including the direction and rate of groundwater flow and the extent of dispersion of total petroleum hydrocarbon contamination. To identify petroleum products residing in contaminated soils, the hump of an unresolved complex mixture on the baseline found in the data of gas chromatography was used as a new method. Based on objective facts obtained from basic investigation, the current state of contamination, and discrimination of oil species, the polluter as specified in the Korean Soil Environment Conservation Act was identified.     

Mapping the top of the permafrost using surface direct current resistivity survey

 Data from a direct current resistivity survey and geologic logs from boreholes were used to map the top of permafrost at a remote air force installation in Alaska. This study resulted from a remedial investigation that was conducted at Eielson Air Force Base near Fairbanks, Alaska, under the federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) regulations. The depth and continuity of the permafrost was important in determining the fate of petroleum contamination that was inadvertently discharged to the ground during earlier air force operations. The results indicate that the top of permafrost forms a highly irregular surface. In general, however, the top of permafrost forms a diagonal ridge at the center of the contour grid that is bordered on each side by troughs. Received: 21 November 1995 · Accepted: 5 March 1996     

Geophysical and hydrogeologic investigation of groundwater in the Karoo stratigraphic sequence at Sawmills in northern Matabeleland,Zimbabwe: a case history

Geophysical and hydrogeological investigations have been carried out around Sawmills in Zimbabwe, Africa. The investigations are components of a larger investigation to assess the groundwater potential of the Karoo sedimentary basin with regards to supplying water to Bulawayo City. The Sawmills area was selected due to the availability of borehole logs indicating favourable stratigraphy for groundwater availability and due to the high yields from the aquifers measured from these boreholes. Data collected using two geophysical methods are presented here: transient electromagnetic (TEM) and continuous vertical electrical sounding (CVES) data. The data have also been processed using laterally constrained inversion (LCI). Because the CVES provides greater detail in the shallow subsurface, whereas TEM is more effective at depth, a more accurate image of the entire subsurface profile is provided based on using both methods. The results suggest that LCI of CVES and TEM data, in the subsurface at the required depths at Sawmills, is able to provide a substantially more accurate image of the subsurface than either method alone. The hydrogeological interpretation of the geophysical data is valuable for determining the depth to and thickness of the potential aquifer horizon(s) and for identifying the position of potential recharge zones.     

Architectural element analysis within the Kayenta Formation (Lower Jurassic) using ground-probing radar and sedimentological profiling, southwestern Colorado

A well exposed outcrop in the Kayenta Formation (Lower Jurassic) in southwestern Colorado was examined in order to delineate the stratigraphy in the subsurface and test the usefulness of ground-probing radar (GPR) in three-dimensional architectural studies.

Two fluvial styles are present within the Kayenta Formation. Sandbodies within the lower third of the outcrop are characterized by parallel laminations that can be followed in the cliff-face for well over 300 m. These sandbodies are sheet-like in appearance, and represent high-energy flood deposits that most likely resulted from episodic floods. The remainder of the outcrop is characterized by concave-up channel deposits with bank-attached and mid-channel macroforms. Their presence suggests a multiple channel river system.

The GPR data collected on the cliff-top, together with sedimentological data, provided a partial three-dimensional picture of the paleo-river system within the Kayenta Formation. The 3-D picture consists of stacked channel-bar lenses approximately 50 m in diameter.

The GPR technique offers a very effective means of delineating the subsurface stratigraphy. Its high resolution capabilities, easy mobility, and rapid rate of data collection make it a useful tool. Its shallow penetration depth and limitation to low-conductivity environments are its only drawbacks.     

地球油气资源潜力是自然科学的基本问题

层序地层学自１９８７年问世以来，在国外如火如荼地发展起来，石油地质界对它的发展尤为关注。然而，在我国却显得举步维艰，进展缓慢。本文讨论了出现这种状况的起因：①不认识地震反射界面基本上是等时面；②认为地震／层序地层学是研究被动大陆边缘海相地层产生的，不适于非海相地层；③常规剖面中的地震反射频率和分辨率太低，不足以进行层序地层学研究；④层序地层学属纯理论科学，脱离油气勘探实际，采纳它的概念可能打气生产秩序。最后文章从正面阐述了开展层序地层学研究的必要性。     

Near-surface seismic refraction applied to exploring subsurface clay layer at a new mining area in southeast Cairo, Egypt

A near-surface seismic refraction survey was conducted at a new mining area located in southeast Cairo, Egypt, to explore the subsurface clay layer for future economic use in mining and cement industry. The purpose of the survey has been to provide geological and geophysical information because no borehole was existent in the area under investigation. The aim of study had been to explain the main characteristics of the subsurface layers. For this purpose, a new technique has been used to acquire and process the data. This technique provides critical information to determine the depth of the subsurface layers, as well as morphology, stratigraphy, and potential locations of the clay layer for future economic use. The thickness and general shape of the clay layer in the whole area were determined and are illustrated in maps.     

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.     

陆相等时地层格架建立方法新探——以冀东高尚堡深层Es3^2＋3油藏为例

近30年时间,层序地层学理论得到了飞速发展,并在石油、煤矿等矿产领域获得了应用,取得了极大的经济效益。层序地层学理论自身不断完善的同时,其突出问题也日益暴露出来:流派众多,多家层序地层学流派对层序的级次、划分方案乃至层序的界线理解各异;不同流派层序地层学者对同一问题看法分歧较大,缺乏广适性;不易制定操作规范;各流派相互融合贯通研究较少。在复杂陆相地层研究中,这些问题尤为突出,并且日益暴露出单一层序地层学流派的不足。由此,决定探讨一种方法思路,力求吸取各家之长,总结出一套陆相地层层序地层学研究方法。分析认为,经典层序地层学和高分辨率层序地层学理论在研究的深度及系统性上、应用的广泛性上比较突出。对两种层序地层学理论基础、层序级次、层序界面等特征分析表明,这两种层序地层学理论上具有相互结合的可能性。为此,以冀东高尚堡深层Es32 3油藏为例,采用经典与高分辨率层序地层学理论相结合的方法,从层序的宏观特征和微观特征出发,建立了工区精细等时层序地层格架。构造格局与沉积特征、生产实践均表明,该地层格架较为合理。理论研究与实践分析表明,在陆相地层研究中,将经典层序地层学与高分辨率层序地层学理论相结合,是提高理论研究的科学性与实际应用效率的有意义的方法。     

Landslide risk evaluation and hazard zoning for rapid and long-travel landslides in urban development areas

Risk evaluation for earthquake-induced rapid and long-travel landslides in densely populated urban areas is currently the most important disaster mitigation task in landslide-threatened areas throughout the world. The research achievements of the IPL M-101 APERITIF project were applied to two urban areas in megacities of Japan. One site is in the upper slope of the Nikawa landslide site where previous movements were triggered by the 1995 Hyogoken-Nambu earthquake. During detailed investigation, the slope was found to be at risk from a rapid and long-travel landslide induced by sliding surface liquefaction by earthquakes similar in scale to the 1995 event. A new plan to prevent the occurrence of this phenomenon was proposed and the plan was implemented. Another area is the Tama residential area near Tokyo. A set of field and laboratory investigations including laser scanner, geological drilling and ring-shear tests showed that there was a risk of sliding surface liquefaction for both sites. A geotechnical computer simulation (Rapid/LS) using the quantitative data obtained in the study allowed urban landslide hazard zoning to be made at individual street level.     

银根-额济纳旗盆地下白垩统银根组的确立

银根—额济纳旗盆地是中国西部的一个中新生代沉积盆地,盆地地层有多种不同的划分。近几年来,盆地经历了详细的石油勘探和地质调查。在地震和钻井勘探过程中,于下白垩统发现了一套新的地层单元,这套地层的古生物、电性、岩性、物理特征及地震层序与上覆和下伏地层有很大差别。这套新地层位于下白垩统上部,定名为银根组(K1y),银根组中部有良好储层,上部泥岩可作为区域性盖层,与下部烃源岩构成良好的生储盖组合,有一定的勘探意义。     

Development and testing of a contamination potential mapping system for a portion of the General Separations Area, Savannah River Site, South Carolina

 A methodology was developed to evaluate and map the contamination potential or aquifer sensitivity of the upper groundwater flow system of a portion of the General Separations Area (GSA) at the Department of Energy's Savannah River Site (SRS) in South Carolina. A Geographic Information System (GIS) was used to integrate diverse subsurface geologic data, soils data, and hydrology utilizing a stack-unit mapping approach to construct mapping layers. This is the first time that such an approach has been used to delineate the hydrogeology of a coastal plain environment. Unit surface elevation maps were constructed for the tops of six Tertiary units derived from over 200 boring logs. Thickness or isopach maps were created for five hydrogeologic units by differencing top and basal surface elevations. The geologic stack-unit map was created by stacking the five isopach maps and adding codes for each stack-unit polygon. Stacked-units were rated according to their hydrogeologic properties and ranked using a logarithmic approach (utility theory) to establish a contamination potential index. Colors were assigned to help display relative importance of stacked-units in preventing or promoting transport of contaminants. The sensitivity assessment included the effects of surface soils on contaminants which are particularly important for evaluating potential effects from surface spills. Hydrogeologic/hydrologic factors did not exhibit sufficient spatial variation to warrant incorporation into contamination potential assessment. Development of this contamination potential mapping system provides a useful tool for site planners, environmental scientists, and regulatory agencies. Received: 1 April 1997 · Accepted: 4 November 1997     

第9届国际遗迹组构专题研讨会综述*

第9届国际遗迹组构专题研讨会于2007年8月13—18日在加拿大卡尔加里大学召开。从会议报告、展板、论文摘要集和野外地质考察可以看出:自1983年遗迹组构概念提出以来,一些新思维、新方法的应用极大地拓宽了遗迹学的研究领域,其已经被广泛应用到地层学和沉积学的诸多领域,并随着油气的勘探与开发得到了迅速发展。海相、陆相遗迹组构分析及其在储集层沉积环境和高分辨率层序地层学精细研究中的应用仍然是当前遗迹学的主题,遗迹组构的CT成像技术和三维可视化模拟在地下水勘查和油气勘探中正在发挥越来越大的作用。     

Geoelectric stratigraphy and subsurface evaluation of quaternary stream sediments at the Cooper Basin,NE Texas

An electrical resistivity survey of a portion of the Cooper Reservoir Basin in northeast Texas has been used to delineate the major lithostratigraphic units of Quaternary flood plain deposits and subsurface paleogeomorphic features of interest to geoarchaeologists. This investigation was conducted to evaluate the fluviatile deposits along the South Sulphur River which flows through Cooper Basin, to identify the basin morphology, and to detect buried geomorphic features. Buried stream channels were considered to be important targets since buried prehistoric site locations are thought to be related to patterns of fluvial facies. Two general techniques were used in the survey. First, soundings were conducted over borehole locations to correlate lithologies with resistivity variations. Second, multiple resistivity profiles were established along traverses across the flood plain. By repeating each traverse but with increased probe separations, a composite of profiles was developed yielding electrical cross-sections of the subsurface. These cross-sections were then interpreted in terms of the lithologic stratigraphy in the basin. Sounding data were evaluated using empirical methods, and profile data were evaluated qualitatively. the sounding data defined the major resistivity horizons which correlate to the primary sedimentary units in the Cooper Basin. Profile data, used to construct resistivity cross-sections, revealed a series of buried erosional features interpreted as channel segments and allowed for the estimation of relative time boundaries within sediments buried under the flood plain as the basin evolved.     

Three-Dimensional Subsurface Structure Model of Kansai International Airport by Integration of Borehole Data and Seismic Profiles

The three-dimensional subsurface structure model around Kansai International Airport (KIX) has been developed based on the geologically and geotechnically investigated results of a large amount of borehole data for estimation of subsidence. The model consists of the alternation of marine clay and coarse deposits. The many seismic surveys and borehole drillings were carried out around the KIX before the constructing the airport. The stratigraphy of the model was renewed by the KIX18-1, which was about 1,300 m long drilling core and was drilled near the 2nd runway of the KIX from 2006 to 2007. In this study, the subsurface geological model was revised by integration of renewed borehole data and seismic profiles to incorporate complex warping structure and heterogenic lateral variation.     

Characterization of groundwater contamination using factor analysis

 The effluent contamination of groundwater at two industrial sites at Visakhapatnam, India, was studied using factor analysis. Thirty groundwater samples near a zinc smelter plant and 19 from the polymers plant were analyzed for specific conductance, chloride, bicarbonate, sulfate, calcium, magnesium, sodium, and potassium. The data were subjected to R-mode factor analysis and the factor scores transferred to areal maps. While magnesium and sulfate are the dominant contaminants at the zinc site, sodium, chloride, and bicarbonate from the effluent are affecting groundwater in the polymers area. Contour maps for each factor suggest the areal extension of the contaminants. Received: 1 March 1995 · Accepted: 18 September 1995     

廊固凹陷古近系层序地层特征及油气储集规律探讨

笔者通过对钻孔岩心资料描述和对比，结合具有系统性，连续性和区域分布特点的地震资料，运用层序地层学和地震地层学基本原理对凹陷区内古近系进行了研究。划分了地层层序，揭示层序地层构造格架，探讨了区域沉积格架特征及其对油气成生，储集的控制作用。     

Fault pattern delineation and structural interpretation of the Gafsa trough (onshore central Tunisia) using gravity data

The purpose of this investigation was to identify subsurface lineaments in Gafsa trough (onshore central Tunisia) after gravity data analysis. The Bouguer and residual gravity maps show a gravity values decrease from west to east associated with subsidence variation and confirmed by a regional seismic reflection profile. The deep structural map of the study area is elaborated after the application of two methods: (1) the automatic lineament tracing after horizontal gravity gradient and (2) 3D Euler method. The dominant trends show approximately NW–SE, E–W, and NE–SW directions. Some of these trends are well correlated with the major faults systems. We can qualify the deep structuration model as a mosaic of quadratic blocks bounded by significant deep flower fault corridors. The elaborated structural map of the study area constitutes also a useful document for rationalizing the future petroleum exploration in the Gafsa trough.