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Sample records for airborne geophysical methods

  1. International Symposium on Airborne Geophysics

    NASA Astrophysics Data System (ADS)

    Mogi, Toru; Ito, Hisatoshi; Kaieda, Hideshi; Kusunoki, Kenichiro; Saltus, Richard W.; Fitterman, David V.; Okuma, Shigeo; Nakatsuka, Tadashi

    2006-05-01

    Airborne geophysics can be defined as the measurement of Earth properties from sensors in the sky. The airborne measurement platform is usually a traditional fixed-wing airplane or helicopter, but could also include lighter-than-air craft, unmanned drones, or other specialty craft. The earliest history of airborne geophysics includes kite and hot-air balloon experiments. However, modern airborne geophysics dates from the mid-1940s when military submarine-hunting magnetometers were first used to map variations in the Earth's magnetic field. The current gamut of airborne geophysical techniques spans a broad range, including potential fields (both gravity and magnetics), electromagnetics (EM), radiometrics, spectral imaging, and thermal imaging.

  2. Magnetic airborne survey - geophysical flight

    NASA Astrophysics Data System (ADS)

    de Barros Camara, Erick; Nei Pereira Guimarães, Suze

    2016-06-01

    This paper provides a technical review process in the area of airborne acquisition of geophysical data, with emphasis for magnetometry. In summary, it addresses the calibration processes of geophysical equipment as well as the aircraft to minimize possible errors in measurements. The corrections used in data processing and filtering are demonstrated with the same results as well as the evolution of these techniques in Brazil and worldwide.

  3. A general framework of TOPSIS method for integration of airborne geophysics, satellite imagery, geochemical and geological data

    NASA Astrophysics Data System (ADS)

    Abedi, Maysam; Norouzi, Gholam-Hossain

    2016-04-01

    This work presents the promising application of three variants of TOPSIS method (namely the conventional, adjusted and modified versions) as a straightforward knowledge-driven technique in multi criteria decision making processes for data fusion of a broad exploratory geo-dataset in mineral potential/prospectivity mapping. The method is implemented to airborne geophysical data (e.g. potassium radiometry, aeromagnetic and frequency domain electromagnetic data), surface geological layers (fault and host rock zones), extracted alteration layers from remote sensing satellite imagery data, and five evidential attributes from stream sediment geochemical data. The central Iranian volcanic-sedimentary belt in Kerman province at the SE of Iran that is embedded in the Urumieh-Dokhtar Magmatic Assemblage arc (UDMA) is chosen to integrate broad evidential layers in the region of prospect. The studied area has high potential of ore mineral occurrences especially porphyry copper/molybdenum and the generated mineral potential maps aim to outline new prospect zones for further investigation in future. Two evidential layers of the downward continued aeromagnetic data and its analytic signal filter are prepared to be incorporated in fusion process as geophysical plausible footprints of the porphyry type mineralization. The low values of the apparent resistivity layer calculated from the airborne frequency domain electromagnetic data are also used as an electrical criterion in this investigation. Four remote sensing evidential layers of argillic, phyllic, propylitic and hydroxyl alterations were extracted from ASTER images in order to map the altered areas associated with porphyry type deposits, whilst the ETM+ satellite imagery data were used as well to map iron oxide layer. Since potassium alteration is generally the mainstay of porphyry ore mineralization, the airborne potassium radiometry data was used. The geochemical layers of Cu/B/Pb/Zn elements and the first component of PCA

  4. Airborne Geophysical Surveys Applied to Hydrocarbon Resource Development Environmental Studies

    NASA Astrophysics Data System (ADS)

    Smith, B. D.; Ball, L. B.; Finn, C.; Kass, A.; Thamke, J.

    2014-12-01

    Application of airborne geophysical surveys ranges in scale from detailed site scale such as locating abandoned well casing and saline water plumes to landscape scale for mapping hydrogeologic frameworks pertinent to ground water and tectonic settings relevant to studies of induced seismicity. These topics are important in understanding possible effects of hydrocarbon development on the environment. In addition airborne geophysical surveys can be used in establishing baseline "snapshots", to provide information in beneficial uses of produced waters, and in mapping ground water resources for use in well development. The U.S. Geological Survey (USGS) has conducted airborne geophysical surveys over more than 20 years for applications in energy resource environmental studies. A majority of these surveys are airborne electromagnetic (AEM) surveys to map subsurface electrical conductivity related to plumes of saline waters and more recently to map hydrogeologic frameworks for ground water and plume migration. AEM surveys have been used in the Powder River Basin of Wyoming to characterize the near surface geologic framework for siting produced water disposal ponds and for beneficial utilization in subsurface drip irrigation. A recent AEM survey at the Fort Peck Reservation, Montana, was used to map both shallow plumes from brine pits and surface infrastructure sources and a deeper concealed saline water plume from a failed injection well. Other reported applications have been to map areas geologically favorable for shallow gas that could influence drilling location and design. Airborne magnetic methods have been used to image the location of undocumented abandoned well casings which can serve as conduits to the near surface for coproduced waters. They have also been used in conjunction with geologic framework studies to understand the possible relationships between tectonic features and induced earthquakes in the Raton Basin. Airborne gravity as well as developing deeper

  5. Alternative analysis of airborne laser data collected within conventional multi-parameter airborne geophysical surveys

    NASA Astrophysics Data System (ADS)

    Ahl, Andreas; Supper, R.; Motschka, K.; Schattauer, I.

    2010-05-01

    . These results encouraged us to apply these methods to airborne geophysical data sets from the United Mexican States. One survey was targeted to provide additional data for advanced groundwater modeling in remote areas of the karstic plateau of Yucatan. Within the other project a sustainable source of water supply for a small settlement on the isolated island of Socorro, 700 km off the Mexican main coast had to be detected. At both survey areas no accurate elevation models or area-wide information about vegetation heights where available before the airborne geophysical survey. The results of these investigations will be presented. From an evaluation of the results it can be concluded that the use of laser altimetry not only provides essential information about the ground clearance of the geophysical instruments but also increases the benefit of the airborne survey for the client by delivering additional information about the survey area. It is clear that the accuracy of the resulting data cannot compete with a high resolution laser scanning survey. However in areas where such information is not available an obvious additional benefit can be achieved without the need to spend money for additional survey campaigns. Currently further studies are launched to investigate the possibility to increase the accuracy of the altitude data by determining roll and pitch of the helicopter by the use of differentially corrected multiple L1/L2 band GPS receiver mounted at fixed positions on the helicopter platform. The above study was partly financed by the Austrian Science Fund, Xplore (L524-N10) project.

  6. Geophysical Methods: an Overview

    NASA Technical Reports Server (NTRS)

    Becker, A.; Goldstein, N. E.; Lee, K. H.; Majer, E. L.; Morrison, H. F.; Myer, L.

    1992-01-01

    Geophysics is expected to have a major role in lunar resource assessment when manned systems return to the Moon. Geophysical measurements made from a lunar rover will contribute to a number of key studies: estimating regolith thickness, detection of possible large-diameter lava tubes within maria basalts, detection of possible subsurface ice in polar regions, detection of conductive minerals that formed directly from a melt (orthomagmatic sulfides of Cu, Ni, Co), and mapping lunar geology beneath the regolith. The techniques that can be used are dictated both by objectives and by our abilities to adapt current technology to lunar conditions. Instrument size, weight, power requirements, and freedom from orientation errors are factors we have considered. Among the geophysical methods we believe to be appropriate for a lunar resource assessment are magnetics, including gradiometry, time-domain magnetic induction, ground-penetrating radar, seismic reflection, and gravimetry.

  7. Monitoring Groundwater Contaminant Plumes Using Airborne Geophysical Data

    NASA Astrophysics Data System (ADS)

    Robinson, Martin; Oftendinger, Ulrich; Ruffell, Alastair; Cowan, Marie; Cassidy, Rachel; Comte, Jean-Christophe; Wilson, Christopher; Desissa, Mohammednur

    2013-04-01

    Under the European Union Water Framework Directive, Member States are required to assess water quality across both surface water and groundwater bodies. Subsurface pollution plumes, originating from a variety of sources, pose a significant direct risk to water quality. The monitoring and characterisation of groundwater contaminant plumes is generally invasive, time consuming and expensive. In particular, adequately capturing the contaminant plume with monitoring installations, when the extent of the feature is unknown and the presence of contamination is only evident from indirect observations, can be prohibitively expensive. This research aims to identify the extent and nature of subsurface contaminant plumes using airborne geophysical survey data. This data was collected across parts of the island of Ireland within the scope of the original Tellus and subsequent Tellus Border projects. The rapid assessment of the airborne electro-magnetic (AEM) data allowed the identification of several sites containing possible contaminant plumes. These AEM anomalies were assessed through the analysis of existing site data and field site inspections, with areas of interest being examined for metallic structures that could affect the AEM data. Electrical resistivity tomography (ERT), ground penetrating radar (GPR) and ground-based electro-magnetic (EM) surveys were performed to ground-truth existing airborne data and to confirm the extent and nature of the affected area identified using the airborne data. Groundwater and surface water quality were assessed using existing field site information. Initial results collected from a landfill site underlain by basalt have indicated that the AEM data, coupled with ERT and GPR, can successfully be used to locate possible plumes and help delineate their extent. The analysis of a range of case study sites exhibiting different geological and environmental settings will allow for the development of a consistent methodology for examining the

  8. Clean enough for industry? An airborne geophysical case study

    SciTech Connect

    Nyquist, J.E.; Beard, L.P.

    1996-11-01

    Data from two airborne geophysical surveys of the Department of Energy`s Oak Ridge Reservation (ORR) were extremely valuable in deciding whether a 1000-acre (400 hectare) parcel of the ORR should be leased to the City of Oak Ridge for industrial development. Our findings, based on electromagnetic and magnetic data, were incorporated in the federally mandated Environmental Assessment Statement (EAS), and in general supported claims that this land was never used as a hazardous waste disposal site. We estimated the amount of iron required to produce each anomaly using a simple dipole model. All anomalies with equivalent sources greater than approximately 1000 kg of iron were checked in the field, and the source of all but one identified as either a bridge, reinforced concrete debris, or a similarly benign object. Additionally, some smaller anomalies (equivalent sources of roughly 500 kg) have been checked; thus far, these also have innocuous sources. Airborne video proved invaluable in identifying logging equipment as the source of some of these anomalies. Geologic noise may account for some of the remaining anomalies. Naturally occurring accumulations of magnetic minerals in the soil on the ORR have been shown to produce anomalies which, at a sensor height of 30 in, are comparable to the anomaly produced by about 500 kg of iron. By comparison, the electronic noise of the magnetic gradiometer, 0.01- 0.02 nT/m, is equivalent to only about 50-100 kg of iron at a 30 m sensor height. The electromagnetic data, combined with field mapping of karst structures, provided evidence of a northeast-southwest striking conduit spanning the parcel. The possible existence of a karst conduit led the EAS authors to conclude that this is a {open_quotes}sensitive hydrologic setting.{close_quotes} We conclude that aerial geophysics is an extremely cost-effective, and efficient technique for screening large tracts of land for environmental characterization.

  9. Clean enough for industry? An airborne geophysical case study

    SciTech Connect

    Nyquist, J.E.; Beard, L.P.

    1996-02-01

    Data from two airborne geophysical surveys of the Department of Energy`s Oak Ridge Reservation (ORR) were extremely valuable in deciding whether a 1000-acre (400 hectare) parcel of the ORR should be released to the City of Oak Ridge for industrial development. Our findings, based on electromagnetic and magnetic data, were incorporated in the federally mandated Environmental Assessment Statement (EAS), and in general supported claims that this land was never used as a hazardous waste disposal site. We estimated the amount of iron required to produce each anomaly using a simple dipole model. All anomalies with equivalent sources greater than approximately 1000 kg of iron were checked in the field, and the source of all but one identified as either a bridge, reinforced concrete debris, or a similarly benign object. Additionally, some smaller anomalies (equivalent sources of roughly 500 kg) have been checked; thus far, these also have innocuous sources. Airborne video proved invaluable in identifying logging equipment as the source of some of these anomalies. Geologic noise may account for some of the remaining anomalies. Naturally occurring accumulations of magnetic minerals in the soil on the ORR have been shown to produce anomalies which, at a sensor height of 30 m, are comparable to the anomaly produced by about 500 kg of iron. By comparison, the electronic noise of the magnetic gradiometer, 0.01--0.02 nT/m, is equivalent to only about 50--100 kg of iron at a 30 m sensor height. The electromagnetic data, combined with field mapping of karst structures, provided evidence of a northeast-southwest striking conduit spanning the parcel. The possible existence of a karst conduit led the EAS authors to conclude that this is a ``sensitive hydrologic setting.`` We conclude that aerial geophysics is an extremely cost-effective, and efficient technique for screening large tracts of land for environmental characterization.

  10. Airborne wireless communication systems, airborne communication methods, and communication methods

    DOEpatents

    Deaton, Juan D.; Schmitt, Michael J.; Jones, Warren F.

    2011-12-13

    An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.

  11. High resolution airborne geophysics at hazardous waste disposal sites

    SciTech Connect

    Beard, L.P.; Nyquist, J.E.; Doll, W.E.; Chong Foo, M.; Gamey, T.J.

    1995-06-01

    In 1994, a high resolution helicopter geophysical survey was conducted over portions of the Oak Ridge Reservation, Tennessee. The 1800 line kilometer survey included multi-frequency electromagnetic and magnetic sensors. The areas covered by the high resolution portion of the survey were selected on the basis of their importance to the environmental restoration effort and on data obtained from the reconnaissance phase of the airborne survey in which electromagnetic, magnetic, and radiometric data were collected over the entire Oak Ridge Reservation in 1992--1993. The high resolution phase had lower sensor heights, more and higher EM frequencies, and tighter line spacings than did the reconnaissance survey. When flying over exceptionally clear areas, the high resolution bird came within a few meters of the ground surface. Unfortunately, even sparse trees and power or phone lines could prevent the bird from being towed safely at low altitude, and over such areas it was more usual for it to be flown at about the same altitude as the bird in the reconnaissance survey, about 30m. Even so, the magnetometers used in the high resolution phase were 20m closer to the ground than in the reconnaissance phase because they were mounted on the tail of the bird rather than on the tow cable above the bird. The EM frequencies used in the high resolution survey ranged from 7400Hz to 67000Hz. Only the horizontal coplanar loop configuration was used in the high resolution flyovers.

  12. Applications of geophysical methods to volcano monitoring

    USGS Publications Warehouse

    Wynn, Jeff; Dzurisin, Daniel; Finn, Carol A.; Kauahikaua, James P.; Lahusen, Richard G.

    2006-01-01

    The array of geophysical technologies used in volcano hazards studies - some developed originally only for volcano monitoring - ranges from satellite remote sensing including InSAR to leveling and EDM surveys, campaign and telemetered GPS networks, electronic tiltmeters and strainmeters, airborne magnetic and electromagnetic surveys, short-period and broadband seismic monitoring, even microphones tuned for infrasound. They include virtually every method used in resource exploration except large-scale seismic reflection. By “geophysical ” we include both active and passive methods as well as geodetic technologies. Volcano monitoring incorporates telemetry to handle high-bandwith cameras and broadband seismometers. Critical geophysical targets include the flux of magma in shallow reservoir and lava-tube systems, changes in active hydrothermal systems, volcanic edifice stability, and lahars. Since the eruption of Mount St. Helens in Washington State in 1980, and the eruption at Pu’u O’o in Hawai’i beginning in 1983 and still continuing, dramatic advances have occurred in monitoring technology such as “crisis GIS” and lahar modeling, InSAR interferograms, as well as gas emission geochemistry sampling, and hazards mapping and eruption predictions. The on-going eruption of Mount St. Helens has led to new monitoring technologies, including advances in broadband Wi-Fi and satellite telemetry as well as new instrumentation. Assessment of the gap between adequate monitoring and threat at the 169 potentially dangerous Holocene volcanoes shows where populations are dangerously exposed to volcanic catastrophes in the United States and its territories . This paper focuses primarily on Hawai’ian volcanoes and the northern Pacific and Cascades volcanoes. The US Geological Survey, the US National Park System, and the University of Utah cooperate in a program to monitor the huge Yellowstone volcanic system, and a separate observatory monitors the restive Long Valley

  13. Survey of subsurface geophysical exploration technologies adaptable to an airborne platform

    SciTech Connect

    Taylor, K.A.

    1992-12-01

    This report has been prepared by the US Department of Energy (DOE) as part of a Research Development Demonstration Testing and Evaluation (RDDT E) project by EG G Energy Measurement's (EG G/EM) Remote Sensing Laboratory. It examines geophysical detection techniques which may be used in Environmental Restoration/Waste Management (ER/WM) surveys to locate buried waste, waste containers, potential waste migratory paths, and aquifer depths. Because of the Remote Sensing Laboratory's unique survey capabilities, only those technologies which have been adapted or are capable of being adapted to an airborne platform were studied. This survey describes several of the available subsurface survey technologies and discusses the basic capabilities of each: the target detectability, required geologic conditions, and associated survey methods. Because the airborne capabilities of these survey techniques have not been fully developed, the chapters deal mostly with the ground-based capabilities of each of the technologies, with reference made to the airborne capabilities where applicable. The information about each survey technique came from various contractors whose companies employ these specific technologies. EG G/EM cannot guarantee or verify the accuracy of the contractor information; however, the data given is an indication of the technologies that are available.

  14. Survey of subsurface geophysical exploration technologies adaptable to an airborne platform

    SciTech Connect

    Taylor, K.A.

    1992-12-01

    This report has been prepared by the US Department of Energy (DOE) as part of a Research Development Demonstration Testing and Evaluation (RDDT&E) project by EG&G Energy Measurement`s (EG&G/EM) Remote Sensing Laboratory. It examines geophysical detection techniques which may be used in Environmental Restoration/Waste Management (ER/WM) surveys to locate buried waste, waste containers, potential waste migratory paths, and aquifer depths. Because of the Remote Sensing Laboratory`s unique survey capabilities, only those technologies which have been adapted or are capable of being adapted to an airborne platform were studied. This survey describes several of the available subsurface survey technologies and discusses the basic capabilities of each: the target detectability, required geologic conditions, and associated survey methods. Because the airborne capabilities of these survey techniques have not been fully developed, the chapters deal mostly with the ground-based capabilities of each of the technologies, with reference made to the airborne capabilities where applicable. The information about each survey technique came from various contractors whose companies employ these specific technologies. EG&G/EM cannot guarantee or verify the accuracy of the contractor information; however, the data given is an indication of the technologies that are available.

  15. Airborne and spaceborne lasers for terrestrial geophysical sensing; Proceedings of the Meeting, Los Angeles, CA, Jan. 14, 15, 1988

    NASA Technical Reports Server (NTRS)

    Allario, Frank (Editor)

    1988-01-01

    The present conference on airborne and spaceborne remote sensing laser applications discusses topics in atmospheric and geophysical sciences-related sensors, lidar and DIAL component and subsystem technologies, and coherent laser experiments and semiconductor laser technologies. Attention is given to airborne lidar measurement of aerosols, a ground-based injection-locked pulsed TEA laser for wind measurements, chemical/biological agent standoff detection methods, lidars for wind shear erosion, laser tuning to selected gas absorption lines in the atmosphere, the NASA lidar-in-space technology experiment, and the Laser Atmospheric Wind Sounder.

  16. Investigation of coastal areas in Northern Germany using airborne geophysical surveys

    NASA Astrophysics Data System (ADS)

    Miensopust, Marion; Siemon, Bernhard; Wiederhold, Helga; Steuer, Annika; Ibs-von Seht, Malte; Voß, Wolfgang; Meyer, Uwe

    2014-05-01

    Since 2000, the German Federal Institute for Geosciences and Natural Resources (BGR) carried out several airborne geophysical surveys in Northern Germany to investigate the coastal areas of the North Sea and some of the North and East Frisian Islands. Several of those surveys were conducted in cooperation with the Leibniz Institute for Applied Geophysics (LIAG). Two helicopter-borne geophysical systems were used, namely the BGR system, which collects simultaneously frequency-domain electromagnetic, magnetic and radiometric data, and the SkyTEM system, a time-domain electromagnetic system developed by the University of Aarhus. Airborne geophysical surveys enable to investigate huge areas almost completely with high lateral resolution in a relatively short time at economic cost. In general, the results can support geological and hydrogeological mapping. Of particular importance are the airborne electromagnetic results, as the surveyed parameter - the electrical conductivity - depends on both lithology and groundwater status. Therefore, they can reveal buried valleys and the distribution of sandy and clayey sediments as well as salinization zones and fresh-water occurrences. The often simultaneously recorded magnetic and radiometric data support the electromagnetic results. Lateral changes of Quaternary and Tertiary sediments (shallow source - several tens of metres) as well as evidences of the North German Basin (deep source - several kilometres) are revealed by the magnetic results. The radiometric data indicate the various mineral compositions of the soil sediments. This BGR/LIAG project aims to build up a geophysics data base (http://geophysics-database.de/) which contains all airborne geophysical data sets. However, the more significant effort is to create a reference data set as basis for monitoring climate or man-made induced changes of the salt-water/fresh-water interface at the German North Sea coast. The significance of problems for groundwater extraction

  17. Geophysical methods for locating abandoned wells

    USGS Publications Warehouse

    Frischknecht, Frank C.; Muth, L.; Grette, R.; Buckley, T.; Kornegay, B.

    1983-01-01

    A preliminary study of the feasibility of using geophysical exploration methods to locate abandoned wells containing steel casing indicated that magnetic methods promise to be effective and that some electrical techniques might be useful as auxiliary methods. Ground magnetic measurements made in the vicinity of several known cased wells yielded total field anomalies with peak values ranging from about 1,500 to 6,000 gammas. The anomalies measured on the ground are very narrow and, considering noise due to other cultural and geologic sources, a line spacing on the order of 50 feet (15.2 m) would be necessary to locate all casings in the test area. The mathematical model used to represent a casing was a set of magnetic pole pairs. By use of a non-linear least squares curve fitting (inversion) program, model parameters which characterize each test casing were determined. The position and strength of the uppermost pole was usually well resolved. The parameters of lower poles were not as well resolved but it appears that the results are adequate for predicting the anomalies which would be observed at aircraft altitudes. Modeling based on the parameters determined from the ground data indicates that all of the test casings could be detected by airborne measurements made at heights of 150 to 200 feet (45.7-61.0 m) above the ground, provided lines spaced as closely as 330 feet (100 m) were used and provided noise due to other cultural and geologic sources is not very large. Given the noise levels of currently available equipment and assuming very low magnetic gradients due to geologic sources, the detection range for total field measurements is greater than that for measurements of the horizontal or vertical gradient of the total intensity. Electrical self-potential anomalies were found to be associated with most of the casings where measurements were made. However, the anomalies tend to be very narrow and, in several cases, they are comparable in magnitude to other small

  18. Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010

    USGS Publications Warehouse

    Ball, Lyndsay B.; Smith, Bruce D.; Minsley, Burke J.; Abraham, Jared D.; Voss, Clifford I.; Astley, Beth N.; Deszcz-Pan, Maria; Cannia, James C.

    2011-01-01

    In June 2010, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of the Yukon Flats and Fort Wainwright study areas in central Alaska. These data were collected to estimate the three-dimensional distribution of permafrost at the time of the survey. These data were also collected to evaluate the effectiveness of these geophysical methods at mapping permafrost geometry and to better define the physical properties of the subsurface in discontinuous permafrost areas. This report releases digital data associated with these surveys. Inverted resistivity depth sections are also provided in this data release, and data processing and inversion methods are discussed.

  19. Airborne geophysical surveys conducted in western Nebraska, 2010: contractor reports and data

    USGS Publications Warehouse

    ,

    2014-01-01

    This report contains three contractor reports and data files for an airborne electromagnetic survey flown from June 28 to July 7, 2010. The first report; “SkyTEM Survey: Nebraska, USA, Data” describes data aquisition and processing from a time-domain electromagnetic and magnetic survey performed by SkyTEM Canada, Inc. (the North American SkyTEM subsidiary), in western Nebraska, USA. Digital data for this report are given in Appendix 1. The airborne geophysical data from the SkyTEM survey subsequently were processed and inverted by Aarhus Geophysics ApS, Aarhus, Denmark, to produce resistivity depth sections along each flight line. The result of that processing is described in two reports presented in Appendix 2, “Processing and inversion of SkyTEM data from USGS Area UTM–13” and “Processing and inversion of SkyTEM data from USGS Area UTM–14.” Funding for these surveys was provided by the North Platte Natural Resources District, the South Platte Natural Resources District, and the Twin Platte Natural Resources District, in Scottsbluff, Sidney, and North Platte, Nebraska, respectively. Any additional information concerning the geophysical data may be obtained from the U.S. Geological Survey Crustal Geophysics and Geochemistry Science Center, Denver Colorado.

  20. Statistical multivariate analysis of airborne geophysical data on the SE border of the Central Lapland Greenstone complex

    SciTech Connect

    Lanne, E.

    1986-11-01

    Statistical multivariate methods for the integrated processing of airborne geophysical data were tested. The data consisted of magnetic, electromagnetic and gamma radiation measurements, to which cluster analysis, principal components analysis and discriminant analysis were applied. Also, auxiliary variables were derived from the original ones and their value was tested. Although the frequency distributions of the data do not favour statistical analysis, the practical results are acceptable. Principal component analyses show geological and technical aspects that are difficult to obtain from the original observations. In cluster analyses, the sources of measured fields control the grouping of variables. Discriminant analysis was applied to the automatic identification of rocks by geophysical data. The rocks investigated are metasediments and metavolcanics, some magnetic and others conductive. When all available geophysical data were included, correct identifications were made in more than 60% of cases. In particular, gamma ray observations were found to improve the discrimination of non-magnetic and non-conductive rocks. The geophysical similarity of rocks studied by cluster analysis depends on electrical and magnetic properties as well as on their origin; the content of radioactive elements in turn is related to the origin.

  1. Satellite imagery and airborne geophysics for geologic mapping of the Edembo area, Eastern Hoggar (Algerian Sahara)

    NASA Astrophysics Data System (ADS)

    Lamri, Takfarinas; Djemaï, Safouane; Hamoudi, Mohamed; Zoheir, Basem; Bendaoud, Abderrahmane; Ouzegane, Khadidja; Amara, Massinissa

    2016-03-01

    Satellite imagery combined with airborne geophysical data and field observations were employed for new geologic mapping of the Edembo area in the Eastern Hoggar (Tuareg Shield, Sahara). Multi-spectral band fusion, filtering, and transformation techniques, i.e., band combination, band-rationing and principal component analysis of ETM+ and ASTER data are used for better spectral discrimination of the different rocks units. A thematic map assessed by field data and available geologic information is compiled by supervised classification of satellite data with high overall accuracy (>90%). The automated extraction technique efficiently aided the detection of the structural lineaments, i.e., faults, shear zones, and joints. Airborne magnetic and Gamma-ray spectrometry data showed the pervasiveness of the large structures beneath the Paleozoic sedimentary cover and aeolian sands. The aeroradiometric K-range is used for discrimination of the high-K granitoids of Djanet from the peralumineous granites of Edembo, and to verify the Silurian sediments with their high K-bearing minerals. The new geological map is considered to be a high resolution improvement on all pre-existing maps of this hardly accessible area in the Tuareg Shield. Integration of the airborne geophysical and space-borne imagery data can hence provide a rapid means of geologically mapping areas hitherto poorly known or difficult to access.

  2. Geophysical methods for road construction and maintenance

    NASA Astrophysics Data System (ADS)

    Rasul, Hedi; Karlson, Caroline; Jamali, Imran; Earon, Robert; Olofsson, Bo

    2015-04-01

    Infrastructure, such as road transportation, is a vital in civilized societies; which need to be constructed and maintained regularly. A large part of the project cost is attributed to subsurface conditions, where unsatisfactory conditions could increase either the geotechnical stabilization measures needed or the design cost itself. A way to collect information of the subsurface and existing installations which can lead to measures reducing the project cost and damage is to use geophysical methods during planning, construction and maintenance phases. The moisture in road layers is an important factor, which will affect the bearing capacity of the construction as well as the maintenances. Moisture in the road is a key factor for a well-functioning road. On the other hand the excessive moisture is the main reason of road failure and problems. From a hydrological point of view geophysical methods could help road planners identify the water table, geological strata, pollution arising from the road and the movement of the pollution before, during and after construction. Geophysical methods also allow road planners to collect valuable data for a large area without intrusive investigations such as with boreholes, i.e. minimizing the environmental stresses and costs. However, it is important to specify the investigation site and to choose the most appropriate geophysical method based on the site chosen and the objective of the investigation. Currently, numerous construction and rehabilitation projects are taking places around the world. Many of these projects are focused on infrastructural development, comprising both new projects and expansion of the existing infrastructural network. Geophysical methods can benefit these projects greatly during all phases. During the construction phase Ground Penetrating radar (GPR) is very useful in combination with Electrical Resistivity (ER) for detecting soil water content and base course compaction. However, ER and Electromagnetic

  3. Mathematical Methods for Geophysics and Space Physics

    NASA Astrophysics Data System (ADS)

    Newman, William I.

    2016-05-01

    Graduate students in the natural sciences - including not only geophysics and space physics but also atmospheric and planetary physics, ocean sciences, and astronomy - need a broad-based mathematical toolbox to facilitate their research. In addition, they need to survey a wider array of mathematical methods that, while outside their particular areas of expertise, are important in related ones. While it is unrealistic to expect them to develop an encyclopedic knowledge of all the methods that are out there, they need to know how and where to obtain reliable and effective insights into these broader areas. Here at last is a graduate textbook that provides these students with the mathematical skills they need to succeed in today's highly interdisciplinary research environment. This authoritative and accessible book covers everything from the elements of vector and tensor analysis to ordinary differential equations, special functions, and chaos and fractals. Other topics include integral transforms, complex analysis, and inverse theory; partial differential equations of mathematical geophysics; probability, statistics, and computational methods; and much more. Proven in the classroom, Mathematical Methods for Geophysics and Space Physics features numerous exercises throughout as well as suggestions for further reading. * Provides an authoritative and accessible introduction to the subject * Covers vector and tensor analysis, ordinary differential equations, integrals and approximations, Fourier transforms, diffusion and dispersion, sound waves and perturbation theory, randomness in data, and a host of other topics * Features numerous exercises throughout * Ideal for students and researchers alike * An online illustration package is available to professors

  4. A survey of natural aggregate properties and characteristics important in remote sensing and airborne geophysics

    USGS Publications Warehouse

    Knepper, D.H.; Langer, W.H.; Miller, S.

    1995-01-01

    Natural aggregate is vital to the construction industry. Although natural aggregate is a high volume/low value commodity that is abundant, new sources are becoming increasingly difficult to find and develop because of rigid industry specifications, political considerations, development and transportation costs, and environmental concerns. There are two primary sources of natural aggregate: (1) exposed or near-surface bedrock that can be crushed, and (2) deposits of sand and gravel. Remote sensing and airborne geophysics detect surface and near-surface phenomena, and may be useful for detecting and mapping potential aggregate sources; however, before a methodology for applying these techniques can be developed, it is necessary to understand the type, distribution, physical properties, and characteristics of natural aggregate deposits. The distribution of potential aggregate sources is closely tied to local geologic history. Conventional exploration for natural aggregate deposits has been largely a ground-based operation, although aerial photographs and topographic maps have been extensively used to target possible deposits. Today, the exploration process also considers factors such as the availability of the land, space and water supply for processing, political and environmental factors, and distance from the market; exploration and planning cannot be separated. There are many physical properties and characteristics by which to judge aggregate material for specific applications; most of these properties and characteristics pertain only to individual aggregate particles. The application of remote sensing and airborne geophysical measurements to detecting and mapping potential aggregate sources, however, is based on intrinsic bulk physical properties and extrinsic characteristics of the deposits that can be directly measured, mathematically derived from measurement, or interpreted with remote sensing and geophysical data. ?? 1995 Oxford UniversityPress.

  5. Geophysical methods for monitoring infiltration in soil

    NASA Astrophysics Data System (ADS)

    Coquet, Yves; Pessel, Marc; Saintenoy, Albane

    2015-04-01

    Geophysics provides useful tools for monitoring water infiltration in soil essentially because they are non-invasive and have a good time-resolution. We present some results obtained on different soils using two geophysical techniques: electrical resistivity tomography (ERT) and ground-penetrating radar (GPR). Infiltration in a loamy soil was monitored using a 2D Wenner array set up under a tension disc infiltrometer. A good imaging of the infiltration bulb below the infiltrometer could be achieved provided a sufficient resistivity contrast between the wet and the dry soil zones. ERT data could be used to invert soil hydraulic properties. However, we found that the information provided by the ERT could be of limited importance in regard to the information provided by the infiltration rate dynamics if the ERT spatial resolution is not small enough to capture the details of the infiltration front at the limit between the wet and dry soil zones. GPR was found to be a good tool to monitor the progression of the infiltration front in a sandy soil. By combining a water transport simulation model (HYDRUS-1D), a method for transforming water content into dielectric permittivity values (CRIM), and an electromagnetic wave propagation model (GprMax), the Mualem-van Genuchten hydraulic parameters could be retrieved from radargrams obtained under constant or falling head infiltration experiments. Both ERT and GPR methods have pros and cons. Time and spatial resolutions are of prime importance to achieve a sufficient sensitivity to all soil hydraulic parameters. Two exploration fields are suggested: the combination of different geophysical methods to explore infiltration in heterogeneous soils, and the development of integrated infiltrometers that allow geophysical measurements while monitoring water infiltration rate in soil.

  6. Peat Depth Assessment Using Airborne Geophysical Data for Carbon Stock Modelling

    NASA Astrophysics Data System (ADS)

    Keaney, Antoinette; McKinley, Jennifer; Ruffell, Alastair; Robinson, Martin; Graham, Conor; Hodgson, Jim; Desissa, Mohammednur

    2013-04-01

    The Kyoto Agreement demands that all signatory countries have an inventory of their carbon stock, plus possible future changes to this store. This is particularly important for Ireland, where some 16% of the surface is covered by peat bog. Estimates of soil carbon stores are a key component of the required annual returns made by the Irish and UK governments to the Intergovernmental Panel on Climate Change. Saturated peat attenuates gamma-radiation from underlying rocks. This effect can be used to estimate the thickness of peat, within certain limits. This project examines this relationship between peat depth and gamma-radiation using airborne geophysical data generated by the Tellus Survey and newly acquired data collected as part of the EU-funded Tellus Border project, together encompassing Northern Ireland and the border area of the Republic of Ireland. Selected peat bog sites are used to ground truth and evaluate the use of airborne geophysical (radiometric and electromagnetic) data and validate modelled estimates of soil carbon, peat volume and depth to bedrock. Data from two test line sites are presented: one in Bundoran, County Donegal and a second line in Sliabh Beagh, County Monaghan. The plane flew over these areas at different times of the year and at a series of different elevations allowing the data to be assessed temporally with different soil/peat saturation levels. On the ground these flight test lines cover varying surface land use zones allowing future extrapolation of data from the sites. This research applies spatial statistical techniques, including uncertainty estimation in geostatistical prediction and simulation, to investigate and model the use of airborne geophysical data to examine the relationship between reduced radioactivity and peat depth. Ground truthing at test line locations and selected peat bog sites involves use of ground penetrating radar, terrestrial LiDAR, peat depth probing, magnetometry, resistivity, handheld gamma

  7. Crisp clustering of airborne geophysical data from the Alto Ligonha pegmatite field, northeastern Mozambique, to predict zones of increased rare earth element potential

    NASA Astrophysics Data System (ADS)

    Eberle, Detlef G.; Daudi, Elias X. F.; Muiuane, Elônio A.; Nyabeze, Peter; Pontavida, Alfredo M.

    2012-01-01

    . The highest probability to meet pegmatite bodies is in close vicinity to (magnetic) amphibole schist occurring in areas where depletion of potassium as indication of metasomatic processes is evident from the airborne radiometric data. Clustering has proven to be a fast and effective method to compile value-added maps from multivariate geophysical datasets. Experience made in the Alto Ligonha pegmatite field encourages adopting this new methodology for mapping other parts of the Mozambique Fold Belt.

  8. Review of geophysical characterization methods used at the Hanford Site

    SciTech Connect

    GV Last; DG Horton

    2000-03-23

    This paper presents a review of geophysical methods used at Hanford in two parts: (1) shallow surface-based geophysical methods and (2) borehole geophysical methods. This review was not intended to be ``all encompassing'' but should represent the vast majority (>90% complete) of geophysical work conducted onsite and aimed at hazardous waste investigations in the vadose zone and/or uppermost groundwater aquifers. This review did not cover geophysical methods aimed at large-scale geologic structures or seismicity and, in particular, did not include those efforts conducted in support of the Basalt Waste Isolation Program. This review focused primarily on the more recent efforts.

  9. Using ground-based geophysics to constrain the interpretation of airborne TEM data recorded across the Okavango Delta, Botswana

    NASA Astrophysics Data System (ADS)

    Podgorski, J. E.; Kalscheuer, T.; Doetsch, J.; Rabenstein, L.; Tshoso, G.; Meier, P.; Horstmeyer, H.; Kgotlhang, L.; Ploug, C.; Auken, E.; Kinzelbach, W. K.; Green, A. G.

    2011-12-01

    The Okavango Delta in northern Botswana is a near endorheic inland delta that has developed over the past ~2 MA in an active graben at the southwestern end of the East Africa Rift System. An annual flood from the north causes a slowly flowing surface water regime in the delta, but previous wetter climatic periods were responsible for intermittent lacustrine environments. The Okavango Delta is the largest permanent water body in the Kalahari Desert and, as such, represents an important resource for wildlife and humans alike. An airborne time-domain electromagnetic (TEM) survey, commissioned by the Botswana government, was undertaken in 2007 for the purpose of better understanding the hydrogeology of the delta. Initial processing and inversion of these data show within the main fan of the delta a resistive 20-50 m thick surface layer underlain by a 30-200 m thick conductive layer. In the upper fan, the conductive layer is underlain by a resistive unit beginning at about 150 m depth. This unit exhibits a dendritic pattern implying a fluvial origin. To help interpret this and other structures, geophysical field work was initiated in early 2011 at various locations in the delta. Seismic reflection and refraction, electrical resistive tomography (ERT), and ground TEM methods were employed. The seismic methods are useful for delineating the boundaries of the weathering and basement layers, whereas ERT provides an independent estimate of the resistivity structure, particularly at shallow depths. Ground TEM allows for a direct comparison with the airborne TEM soundings, helping to estimate the accuracy of the latter. Though still evolving, the current large-scale hydrogeological interpretation of the airborne data set includes a fresh water-saturated surface layer underlain by a saline aquifer and clay aquitard. In the upper fan of the delta, a fresh water aquifer appears to lie between the aquitard and the basement rock.

  10. Measuring Geophysical Parameters of the Greenland Ice Sheet using Airborne Radar Altimetry

    NASA Technical Reports Server (NTRS)

    Ferraro, Ellen J.; Swift. Calvin T.

    1995-01-01

    This paper presents radar-altimeter scattering models for each of the diagenetic zones of the Greenland ice sheet. AAFE radar- altimeter waveforms obtained during the 1991 and 1993 NASA multi-sensor airborne altimetry experiments over Greenland reveal that the Ku-band return pulse changes significantly with the different diagenetic zones. These changes are due to varying amounts of surface and volume scattering in the return waveform. In the ablation and soaked zones, where surface scattering dominates the AAFE return, geophysical parameters such as rms surface height and rms surface slope are obtained by fitting the waveforms to a surface-scattering model. Waveforms from the percolation zone show that the sub-surface ice features have a much more significant effect on the return pulse than the surrounding snowpack. Model percolation waveforms, created using a combined surface- and volume-scattering model and an ice-feature distribution obtained during the 1993 field season, agree well with actual AAFE waveforms taken in the same time period. Using a combined surface- and volume-scattering model for the dry-snow-zone return waveforms, the rms surface height and slope and the attenuation coefficient of the snowpack are obtained. These scattering models not only allow geophysical parameters of the ice sheet to be measured but also help in the understanding of satellite radar-altimeter data.

  11. Subsurface geologic features of the 2011 central Virginia earthquakes revealed by airborne geophysics

    USGS Publications Warehouse

    Shah, Anjana K.; Horton, J. Wright; Burton, William C.; Spears, David B; Gilmer, Amy K

    2014-01-01

    Characterizing geologic features associated with major earthquakes provides insights into mechanisms contributing to fault slip and assists evaluation of seismic hazard. We use high-resolution airborne geophysical data combined with ground sample measurements to image subsurface geologic features associated with the 2011 Mw5.8 central Virginia intraplate earthquake and its aftershocks. Geologic mapping and magnetic data analyses suggest that the earthquake occurred near a complex juncture of geologic contacts. These contacts also intersect a >60-km long linear gravity gradient. Distal aftershocks occurred in tight, ~1 km-wide clusters near other obliquely oriented contacts that intersect gravity gradients, contrasting more linearly distributed seismicity observed at other seismic zones. These data and corresponding models suggest that local density contrasts (manifested as gravity gradients) modified the nearby stress regime in a manner favoring failure. However, along those gradients seismic activity is localized near structural complexities, suggesting a significant contribution from enhanced rheological weakness and/or increased rock permeability over limited areas. Regional magnetic data show a broader bend in geologic structures within the Central Virginia seismic zone, suggesting that nearby seismic activity may also be enhanced near localized rheological weaknesses and/or rock permeability. In contrast, away from the Mw5.8 epicenter geophysical lineaments are nearly continuous for tens of kilometers, especially toward the northeast. Continuity of associated geologic structures likely contributed to efficient propagation of seismic energy in that direction, consistent with moderate to high levels of damage from Louisa County to Washington, D.C. and neighboring communities.

  12. Ultra-sensitive electrostatic planar acceleration gradiometer for airborne geophysical surveys

    NASA Astrophysics Data System (ADS)

    Douch, Karim; Christophe, Bruno; Foulon, Bernard; Panet, Isabelle; Pajot-Métivier, Gwendoline; Diament, Michel

    2014-10-01

    We propose a new concept of gravity gradiometer, GREMLIT, for the determination of the spatial derivatives of gravitational acceleration during airborne surveys. The core of this instrument is the acceleration gradiometer composed of four ultra-sensitive electrostatic planar accelerometers, inheriting from technologies developed for the GRACE and GOCE satellite gravity missions. Data from these missions have greatly improved our knowledge of the Earth’s gravity field and its time variations. However, resolving wavelengths of a few 10 km or less, beyond the reach of the satellite resolution, is of utmost importance to study a number of crustal geophysical processes and geological structures. We first present the benefits for a new gravity gradiometer, then we describe the planar acceleration gradiometer, which put together with three orthogonal gyroscopes, constitutes the gravity gradiometer GREMLIT. The acceleration gradiometer enables measurement at one point of the horizontal spatial derivatives of the acceleration horizontal components. We explain the measurement principle and describe the computation of the gravity gradients along with the necessary ancillary measurements. From a detailed error budget analysis of the accelerometers, an expected spectral sensitivity below \\text{1E/}\\sqrt{\\text{Hz}} is found in the [10-3, 0.2] Hz measurement bandwidth. To maintain such performance in flight, we finally discuss the adaptation of the acceleration gradiometer to the turbulent airborne environment. To limit the saturation of the accelerometers, we propose to cancel the common-mode output of the acceleration gradiometer by integrating the instrument on a double-gimbal platform controlled by the common-mode. We demonstrate on a real case study that with such a solution, it is technically possible to prevent the saturation of the accelerometers at least 95% of the time and it is not damaging to the airborne survey.

  13. Mapping mine tailings using airborne geophysical and hyperspectral remote sensing data

    NASA Astrophysics Data System (ADS)

    Shang, Jiali

    Mine tailings are the waste products from mining operations. Most mine tailings contain a considerable amount of reactive sulphides which can cause acid mine drainage (AMD) when exposed to air and water. AMD constitutes a threat both to the environment and to public health. Increased awareness of AMD has led to growing activities in mine-tailing monitoring and reclamation worldwide. Mining companies in Canada are required to provide information to provincial governments about their waste disposal and control activities. There is an urgent need to develop new automated ways to provide information on short- to long-term evolution of tailings, thus enabling the mining companies to monitor their tailings more effectively. The overall goal of the thesis is to explore the potential of hyperspectral remote sensing and geophysical techniques for mapping variations within and immediately outside of the tailings. Data used for this study are from three sources: airborne geophysical data, hyperspectral casi and Probe-1 data, and field data. This study has contributed to both the remote sensing data analysis techniques and the understanding of mine-tailing surface and subsurface processes. Specifically, this study has the following important findings: (1) Airborne magnetic and electromagnetic data can provide information regarding the subsurface distribution of mine tailings on the basis of sulphide mineral content. A procedure has been developed in this study to use these data sources for rapidly surveying large tailings areas. This procedure can minimize expenditures for mining companies when designing remedial plans for the closure of the mines. This study has also identified regions of enhanced conductivity that extend beyond the tailing containment area. This information indicates seepage pathways, and is important for monitoring the effectiveness of tailing containment structures. (2) High-spatial-resolution hyperspectral casi (Compact Airborne Spectrographic Imagery

  14. Three decades of BGR airborne geophysical surveys over the polar regions - a review

    NASA Astrophysics Data System (ADS)

    Damaske, Detlef

    2013-04-01

    The Federal Institute for Geosciences and Natural Resources (BGR) has been conducting geological polar research since 1979. A few years later BGR engaged in airborne geophysical projects. Investigation of the lithosphere of the continent and the continental margins was one of the key issues for BGR. Right from the beginning geophysical research was closely associated with the geological activities. The GANOVEX (German Antarctic North Victoria Land Expedition) program combined geological research with geophysical (mainly airborne) investigations. This proved to be a fruitful approach to many of the open questions regarding the tectonic development of the Ross Sea region. Aeromagnetic surveys evolved into a powerful tool for identifying geological structures and following them underneath the ice covered areas - not accessible to direct geological investigations. To achieve this aim it was essential to lay out these surveys with a relatively closely spaced line separation on the expense of covering large areas at the same time. Nevertheless, over many years of continues research areas of more than a just regional extent could be covered. This was, however, only possible through international collaboration. During the first years, working in the Ross Sea area, the cooperation with the US and Italian programs played a significant role, especially the GITARA (German-Italian Aeromagnetic Research in Antarctica) program has to be mentioned. GEOMAUD (Geoscientific Expedition to Dronning Maud Land) and the German-Australian joint venture PCMEGA (Prince Charles Mountains Expedition of Germany & Australia) expanded research activities to the East Antarctic shield area. In the International Polar Year (IPY), BGR played a leading role in the international project AGAP (Antarctica's GAmburtsev Province) as part of the main topic "Venture into Unknown Regions". AGAP was jointly conducted by the USA, Great Britain, Australia, China and Germany. While in the Ross Sea area even

  15. Contribution of the airborne geophysical survey to the study of the regolith : A case study in southern Paris Basin.

    NASA Astrophysics Data System (ADS)

    Prognon, Francois; Lacquement, Fréderic; Deparis, Jacques; Martelet, Guillaume; Perrin, José

    2010-05-01

    Studies of soil and subsoil, also called regolith, are at the crossroads of scientific new challenging questions as well as new environmental needs. Historically, geological maps were focussed on solid geology. Present societal needs increasingly require knowledge of regolith properties: superficial studies combining geology, geochemistry and geophysics become essential to better understand the natural processes which govern the repartition and evolution of subsoil formations. Such progress is critical to better orient the use and management of natural and groundwater resources. Among other techniques, airborne geophysics is appropriate to provide information on near surface, because of i) its high spatial coverage ii) the rapidity of acquisition and iii) the variety of available sensors (magnetic, spectral radiometry, electromagnetic …). We illustrate the results of an airborne geophysical survey carried out in France, in "Région Centre" administrative region in the southern part of the Paris Basin. Spectral radiometry data were collected throughout "Région Centre" with a line spacing of 1 km. This method provides maps of potassium (K), uranium (U) and thorium (Th) which are the only naturally occurring elements with direct or indirect radioisotopes that produce gamma rays of sufficient intensity to be measured at airborne survey heights. Gamma-rays emitted from the Earth surface are related to the primary mineralogy and geochemistry of the bedrock and/or the nature of secondary weathering including regolith materials. Obtained images are confronted with former geological investigations (1:50 000e geological maps). Geophysical data and geological maps are generally consistent on most of the covered area since the first-rate information delivered by the spectrometry derives from the geochemistry of the solid geology. Second-rate gamma-ray responses come from superimposed allochtonous deposits as well as in situ geochemical modifications. For instance

  16. Monitoring Vadose Zone Desiccation with Geophysical Methods

    SciTech Connect

    Truex, Michael J.; Johnson, Timothy C.; Strickland, Christopher E.; Peterson, John E.; Hubbard, Susan S.

    2013-05-01

    Soil desiccation was recently field tested as a potential vadose zone remediation technology. Desiccation removes water from the vadose zone and significantly decreases the aqueous-phase permeability of the desiccated zone, thereby decreasing movement of moisture and contaminants. The 2-D and 3-D distribution of moisture content reduction over time provides valuable information for desiccation operations and for determining when treatment goals have been reached. This type of information can be obtained through use of geophysical methods. Neutron moisture logging, cross-hole electrical resistivity tomography, and cross-hole ground penetrating radar approaches were evaluated with respect to their ability to provide effective spatial and temporal monitoring of desiccation during a treatability study conducted in the vadose zone of the DOE Hanford Site in WA.

  17. A fractured rock geophysical toolbox method selection tool

    USGS Publications Warehouse

    Day-Lewis, F. D.; Johnson, C.D.; Slater, L.D.; Robinson, J.L.; Williams, J.H.; Boyden, C.L.; Werkema, D.D.; Lane, J.W.

    2016-01-01

    Geophysical technologies have the potential to improve site characterization and monitoring in fractured rock, but the appropriate and effective application of geophysics at a particular site strongly depends on project goals (e.g., identifying discrete fractures) and site characteristics (e.g., lithology). No method works at every site or for every goal. New approaches are needed to identify a set of geophysical methods appropriate to specific project goals and site conditions while considering budget constraints. To this end, we present the Excel-based Fractured-Rock Geophysical Toolbox Method Selection Tool (FRGT-MST). We envision the FRGT-MST (1) equipping remediation professionals with a tool to understand what is likely to be realistic and cost-effective when contracting geophysical services, and (2) reducing applications of geophysics with unrealistic objectives or where methods are likely to fail.

  18. Airborne Geophysical Surveys Illuminate the Geologic and Hydrothermal Framework of the Pilgrim Springs Geothermal Area, Alaska

    NASA Astrophysics Data System (ADS)

    McPhee, D. K.; Glen, J. M.; Bedrosian, P. A.

    2012-12-01

    An airborne magnetic and frequency-domain electromagnetic (EM) survey of the Pilgrim Springs geothermal area, located on the Seward Peninsula in west-central Alaska, delineates key structures controlling hydrothermal fluid flow. Hot springs, nearby thawed regions, and high lake temperatures are indicative of high heat flow in the region that is thought to be related to recent volcanism. By providing a region-wide geologic and geophysical framework, this work will provide informed decisions regarding drill-site planning and further our understanding of geothermal systems in active extensional basins. Helicopter magnetic and EM data were acquired using a Fugro RESOLVE system equipped with a high sensitivity cesium magnetometer and a multi-coil, multi-frequency EM system sensitive to the frequency range of 400-140,000 Hz. The survey was flown ~40 m above ground along flight lines spaced 0.2-0.4 km apart. Various derivative and filtering methods, including maximum horizontal gradient of the pseudogravity transformation of the magnetic data, are used to locate faults, contacts, and structural domains. A dominant northwest trending anomaly pattern characterizes the northeastern portion of the survey area between Pilgrim Springs and Hen and Chickens Mountain and may reflect basement structures. The area south of the springs, however, is dominantly characterized by east-west trending, range-front-parallel anomalies likely caused by late Cenozoic structures associated with the north-south extension that formed the basin. Regionally, the springs are characterized by a magnetic high punctuated by several east-west trending magnetic lows, the most prominent occurring directly over the springs. The lows may result from demagnetization of magnetic material along range-front parallel features that dissect the basin. We inverted in-phase and quadrature EM data along each profile using the laterally-constrained inversion of Auken et al. (2005). Data were inverted for 20-layer

  19. Magnetotellurics as a multiscale geophysical exploration method

    NASA Astrophysics Data System (ADS)

    Carbonari, Rolando; D'Auria, Luca; Di Maio, Rosa; Petrillo, Zaccaria

    2016-04-01

    Magnetotellurics (MT) is a geophysical method based on the use of natural electromagnetic signals to define subsurface electrical resistivity structure through electromagnetic induction. MT waves are generated in the Earth's atmosphere and magnetosphere by a range of physical processes, such as magnetic storms, micropulsations, lightning activity. Since the underground MT wave propagation is of diffusive type, the longer is the wavelength (i.e. the lower the wave frequency) the deeper will be the propagation depth. Considering the frequency band commonly used in MT prospecting (10-4 Hz to 104 Hz), the investigation depth ranges from few hundred meters to hundreds of kilometers. This means that magnetotellurics is inherently a multiscale method and, thus, appropriate for applications at different scale ranging from aquifer system characterization to petroleum and geothermal research. In this perspective, the application of the Wavelet transform to the MT data analysis could represent an excellent tool to emphasize characteristics of the MT signal at different scales. In this note, the potentiality of such an approach is studied. In particular, we show that the use of a Discrete Wavelet (DW) decomposition of measured MT time-series data allows to retrieve robust information about the subsoil resistivity over a wide range of spatial (depth) scales, spanning up to 5 orders of magnitude. Furthermore, the application of DWs to MT data analysis has proven to be a flexible tool for advanced data processing (e.g. non-linear filtering, denoising and clustering).

  20. Airborne geophysical survey of ice caps in the Queen Elizabeth Islands, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Palmer, S. J.; Dowdeswell, J. A.; Christoffersen, P.; Benham, T. J.; Young, D. A.; Blankenship, D. D.; Richter, T.; Ng, G.; Grima, C.; Habbal, F.; Sharp, M. J.; Rutishauser, A.

    2014-12-01

    Previous studies have shown that between 2003 and 2009, 60 ± 6 Gt of ice was lost each year from the Canadian Arctic (Gardner et al., 2013), making the region the largest cryospheric contributor to global sea level rise outside of the great ice sheets. Glacier ice in the Queen Elizabeth Islands (QEI) currently covers more than 100,000 km2, representing 20% of Earth's ice-covered land area outside of Greenland and Antarctica. The vast majority of this ice is stored within six ice caps located on Ellesmere, Devon and Axel Heiberg islands. Recent satellite observations of the outlet glaciers draining these ice caps have revealed significant velocity variability on inter-annual and multi-year timescales (Van Wychen et al., 2014), though the drivers of these dynamics are not yet understood. Here we present results obtained in May 2014 during an airborne geophysical survey of the ice caps of Axel Heiberg, Ellesmere and Devon islands, including Agassiz Ice Cap (17,300 km2), Prince of Wales Icefield (19,300 km2) and Devon Ice Cap (14,000 km2). We used a Basler BT-67 aircraft equipped with a suite of geophysical instruments, including a phase-coherent VHF ice-penetrating radar, to measure ice thickness and investigate ice basal conditions along outlet glacier flow lines and in the interior of the ice caps. We reveal that the glaciers draining the ice caps of the QEI exhibit diverse characteristics over short spatial scales, and that fast-flowing tidewater glaciers are located adjacent to previously fast-flowing areas that have subsequently stagnated. Our results show that many ice cap outlet glaciers on Ellesmere and Devon islands are between 700 and 1000 m thick and flow through deep bedrock troughs whose beds lie below sea-level. Some of the outlet glaciers also have floating tongues of ice which extend into the adjacent fjord waters. We intend to use our results to characterize the substrate beneath the ice, and to reveal any variations in conditions at the ice

  1. Application of geophysical methods to agriculture: An overview

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods are becoming an increasingly valuable tool for agricultural applications. Agricultural geophysics investigations are commonly (although certainly not always) focused on delineating small- and/or large-scale objects/features within the soil profile (~ 0 to 2 m depth) over very lar...

  2. GENERAL CONSIDERATIONS FOR GEOPHYSICAL METHODS APPLIED TO AGRICULTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysics is the application of physical quantity measurement techniques to provide information on conditions or features beneath the earth’s surface. With the exception of borehole geophysical methods and soil probes like a cone penetrometer, these techniques are generally noninvasive with physica...

  3. Geophysics

    NASA Technical Reports Server (NTRS)

    Carr, M. H.; Cassen, P.

    1976-01-01

    Four areas of investigation, each dealing with the measurement of a particular geophysical property, are discussed. These properties are the gravity field, seismicity, magnetism, and heat flow. All are strongly affected by conditions, past or present, in the planetary interior; their measurement is the primary source of information about planetary interiors.

  4. Methods for Sampling of Airborne Viruses

    PubMed Central

    Verreault, Daniel; Moineau, Sylvain; Duchaine, Caroline

    2008-01-01

    Summary: To better understand the underlying mechanisms of aerovirology, accurate sampling of airborne viruses is fundamental. The sampling instruments commonly used in aerobiology have also been used to recover viruses suspended in the air. We reviewed over 100 papers to evaluate the methods currently used for viral aerosol sampling. Differentiating infections caused by direct contact from those caused by airborne dissemination can be a very demanding task given the wide variety of sources of viral aerosols. While epidemiological data can help to determine the source of the contamination, direct data obtained from air samples can provide very useful information for risk assessment purposes. Many types of samplers have been used over the years, including liquid impingers, solid impactors, filters, electrostatic precipitators, and many others. The efficiencies of these samplers depend on a variety of environmental and methodological factors that can affect the integrity of the virus structure. The aerodynamic size distribution of the aerosol also has a direct effect on sampler efficiency. Viral aerosols can be studied under controlled laboratory conditions, using biological or nonbiological tracers and surrogate viruses, which are also discussed in this review. Lastly, general recommendations are made regarding future studies on the sampling of airborne viruses. PMID:18772283

  5. GEOPHYSICAL METHODS FOR COAL FIRE DETECTION AND MONITORING

    NASA Astrophysics Data System (ADS)

    Meyer, U.; Gundelach, V.; Vasterling, M.; Lambrecht, A.; Rueter, H.; Lindner, H.

    2009-12-01

    Within the framework of the Sino-German research initiative "Innovative technologies for exploration, extinction and monitoring of coal fires in Northern China" a number of different geophysical methods have been applied to determine their use on coal fire detecting, accompanying the extinguishing processes, controlling of the extinction and finally monitoring the extinction success. It is known that the heating of coal resp. coal host rocks changes its electrical resistivity and magnetic susceptibility. Hence the methods of choice are airborne magnetics and frequency electromagnetics (AEM) for surveying large and inaccessible areas and ground based magnetics, transient electromagnetics (TEM), ground penetrating radar (GPR) and temperature measurements to obtain detailed local information. Ground based and airborne magnetics show positive anomalies on coal fire areas. Susceptibility of sandstone, coal and (burnt) clay samples were determined in-situ. The magnetisation was strikingly high for thermally altered clay and slightly increased for thermally influenced sandstone. They get remanently magnetised according to the earth’s recent magnetic field when cooling down below Curie temperature as the fire propagates. Additionally, at a certain temperature non-magnetic minerals like pyrite chemically react to magnetic minerals like magnetite. Thus the observed magnetic anomalies indicate burnt areas. From ground based magnetics the anomalies were more distinct whereas using an airborne system a larger area and also inaccessible terrain can be surveyed. Performing TEM measurements a change in data curves can be observed where the profiles cross the hot burning zone. Heat and fluid transport included in the burning processes presumably change the permittivity of the rock. The electrical resistivity of thermally influenced coal is strongly decreased. Furthermore, the condensed mineralised process water in the rocks above the burning seams forms a layer of low resistivity

  6. Time-reversal methods in geophysics

    SciTech Connect

    Larmat, Carene S.; Guyer, Robert A.; Johnson, Paul A.

    2010-08-15

    Before the 20th century there were few seismometers. So Earth's dynamic geophysical processes were poorly understood. Today the potential for understanding those processes is enormous: The number of seismic instruments is continually increasing, their data are easily stored and shared, and computing power grows exponentially. As a result, seismologists are rapidly discovering new kinds of seismic signals in the frequency range 0.001-100 Hz, as well as relatively large nonseismic displacements, monitored by the global positioning system, occurring over days or weeks.

  7. Interpretation of an airborne geophysical survey in southern Paris Basin: towards a lithological cartography, key tool for the management of shrinking/swelling clay problems

    NASA Astrophysics Data System (ADS)

    Prognon, F.; Tourliere, B.; Perrin, J.; Lacquement, F.; Martelet, G.; Deparis, J.; Gourdier, S.; Drufin, S.

    2011-12-01

    Regolith formations support a full spectrum of human activities. Among others, they provide a source of extractable materials and form the substratum of soils. As such, they should be considered as a capital to be managed and protected. Moreover, one of the main challenges for present and future land settlement is to prevent house building programs from being planned inside shrink-swell risky areas which is only possible thanks to an complete lithological mapping of the french regolith. We illustrate here the results of the geological interpretation of an airborne geophysical survey carried out in "Région Centre" administrative region in the southern part of the Paris Basin, in France. Among other techniques, airborne geophysics is appropriate to quickly provide information on near surface, because of i) its high spatial coverage ii) the rapidity of acquisition and iii) the variety of available sensors (magnetic, spectral radiometry, electromagnetic...). Spectral radiometry data were collected with a line spacing of 1 km. This method provides maps of potassium (K), uranium (U) and thorium (Th) which are the only naturally occurring elements with direct or indirect radioisotopes that produce gamma rays of sufficient intensity to be measured at airborne survey heights. On the radiometric data we applied the HAC (Hierarchical Ascendant Classification) computation procedure: taking into account several variables, the statistical HAC method groups individuals based on their resemblance. Also in this study, calibrated Total Count channel (TCm) is compared to an estimated dose rate (TCe) computed from the measured radioelement abundances: TCe = 13.078 * K + 5.675 * U + 2.494 * Th. Our results show that the ratio TCe/TCm came out to be a good indicator of ground property changes within Sologne mixed sandy-clay environment. Processed geophysical data are cross-checked with geological data (from field observations) and field or laboratory measurements of mineralogical data

  8. Remote sensing and airborne geophysics in the assessment of natural aggregate resources

    USGS Publications Warehouse

    Knepper, D.H.; Langer, W.H.; Miller, S.H.

    1994-01-01

    Natural aggregate made from crushed stone and deposits of sand and gravel is a vital element of the construction industry in the United States. Although natural aggregate is a high volume/low value commodity that is relatively abundant, new sources of aggregate are becoming increasingly difficult to find and develop because of rigid industry specifications, political considerations, development and transporation costs, and environmental concerns, especially in urban growth centers where much of the aggregate is used. As the demand for natural aggregate increases in response to urban growth and the repair and expansion of the national infrastructure, new sources of natural aggregate will be required. The USGS has recognized the necessity of developing the capability to assess the potential for natural aggregate sources on Federal lands; at present, no methodology exists for systematically describing and evaluating potential sources of natural aggregate. Because remote sensing and airborne geophysics can detect surface and nearsurface phenomena, these tools may useful for detecting and mapping potential sources of natural aggregate; however, before a methodology for applying these tools can be developed, it is necessary to understand the type, distribution, physical properties, and characteristics of natural aggregate deposits, as well as the problems that will be encountered in assessing their potential value. There are two primary sources of natural aggregate: (1) exposed or near-surface igneous, metamorphic, and sedimentary bedrock that can be crushed, and (2) deposits of sand and gravel that may be used directly or crushed and sized to meet specifications. In any particular area, the availability of bedrock suitable for crushing is a function of the geologic history of the area - the processes that formed, deformed, eroded and exposed the bedrock. Deposits of sand and gravel are primarily surficial deposits formed by the erosion, transportation by water and ice

  9. A Simple Method for Collecting Airborne Pollen

    ERIC Educational Resources Information Center

    Kevan, Peter G.; DiGiovanni, Franco; Ho, Rong H.; Taki, Hisatomo; Ferguson, Kristyn A.; Pawlowski, Agata K.

    2006-01-01

    Pollination is a broad area of study within biology. For many plants, pollen carried by wind is required for successful seed set. Airborne pollen also affects human health. To foster studies of airborne pollen, we introduce a simple device--the "megastigma"--for collecting pollen from the air. This device is flexible, yielding easily obtained data…

  10. Well casing-based geophysical sensor apparatus, system and method

    DOEpatents

    Daily, William D.

    2010-03-09

    A geophysical sensor apparatus, system, and method for use in, for example, oil well operations, and in particular using a network of sensors emplaced along and outside oil well casings to monitor critical parameters in an oil reservoir and provide geophysical data remote from the wells. Centralizers are affixed to the well casings and the sensors are located in the protective spheres afforded by the centralizers to keep from being damaged during casing emplacement. In this manner, geophysical data may be detected of a sub-surface volume, e.g. an oil reservoir, and transmitted for analysis. Preferably, data from multiple sensor types, such as ERT and seismic data are combined to provide real time knowledge of the reservoir and processes such as primary and secondary oil recovery.

  11. Applied high resolution geophysical methods: Offshore geoengineering hazards

    SciTech Connect

    Trabant, P.K.

    1984-01-01

    This book is an examination of the purpose, methodology, equipment, and data interpretation of high-resolution geophysical methods, which are used to assess geological and manmade engineering hazards at offshore construction locations. It is a state-of-the-art review. Contents: 1. Introduction. 2. Maring geophysics, an overview. 3. Marine geotechnique, an overview. 4. Echo sounders. 5. Side scan sonar. 6. Subbottom profilers. 7. Seismic sources. 8. Single-channel seismic reflection systems. 9. Multifold acquisition and digital processing. 10. Marine magnetometers. 11. Marine geoengineering hazards. 12. Survey organization, navigation, and future developments. Appendix. Glossary. References. Index.

  12. OPTIMIZING THE PAKS METHOD FOR MEASURING AIRBORNE ACROLEIN

    EPA Science Inventory

    Airborne acrolein is produced from the combustion of fuel and tobacco and is of concern due to its potential for respiratory tract irritation and other adverse health effects. DNPH active-sampling is a method widely used for sampling airborne aldehydes and ketones (carbonyls); ...

  13. Geophysical Methods for Investigating Ground-Water Recharge

    USGS Publications Warehouse

    Ferre, Ty P.A.; Binley, Andrew M.; Blasch, Kyle W.; Callegary, James B.; Crawford, Steven M.; Fink, James B.; Flint, Alan L.; Flint, Lorraine E.; Hoffmann, John P.; Izbicki, John A.; Levitt, Marc T.; Pool, Donald R.; Scanlon, Bridget R.

    2007-01-01

    While numerical modeling has revolutionized our understanding of basin-scale hydrologic processes, such models rely almost exclusively on traditional measurements?rainfall, streamflow, and water-table elevations?for calibration and testing. Model calibration provides initial estimates of ground-water recharge. Calibrated models are important yet crude tools for addressing questions about the spatial and temporal distribution of recharge. An inverse approach to recharge estimation is taken of necessity, due to inherent difficulties in making direct measurements of flow across the water table. Difficulties arise because recharging fluxes are typically small, even in humid regions, and because the location of the water table changes with time. Deep water tables in arid and semiarid regions make recharge monitoring especially difficult. Nevertheless, recharge monitoring must advance in order to improve assessments of ground-water recharge. Improved characterization of basin-scale recharge is critical for informed water-resources management. Difficulties in directly measuring recharge have prompted many efforts to develop indirect methods. The mass-balance approach of estimating recharge as the residual of generally much larger terms has persisted despite the use of increasing complex and finely gridded large-scale hydrologic models. Geophysical data pertaining to recharge rates, timing, and patterns have the potential to substantially improve modeling efforts by providing information on boundary conditions, by constraining model inputs, by testing simplifying assumptions, and by identifying the spatial and temporal resolutions needed to predict recharge to a specified tolerance in space and in time. Moreover, under certain conditions, geophysical measurements can yield direct estimates of recharge rates or changes in water storage, largely eliminating the need for indirect measures of recharge. This appendix presents an overview of physically based, geophysical methods

  14. Hydrogeological-Geophysical Methods for Subsurface Site Characterization - Final Report

    SciTech Connect

    Rubin, Yoram

    2001-01-01

    The goal of this research project is to increase water savings and show better ecological control of natural vegetation by developing hydrogeological-geophysical methods for characterizing the permeability and content of water in soil. The ground penetrating radar (GPR) tool was developed and used as the surface geophysical method for monitoring water content. Initial results using the tool suggest that surface GPR is a viable technique for obtaining precision volumetric water content profile estimates, and that laboratory-derived petrophysical relationships could be applied to field-scale GPR data. A field-scale bacterial transport study was conducted within an uncontaminated sandy Pleistocene aquifer to evaluate the importance of heterogeneity in controlling the transport of bacteria. Geochemical, hydrological, geological, and geophysical data were collected to characterize the site prior to and after chemical and bacterial injection experiments. Study results shows that, even within the fairly uniform shallow marine deposits of the narrow channel focus area, heterogeneity existed that influenced the chemical tracer transport over lateral distances of a few meters and vertical distances of less than a half meter. The interpretation of data suggest that the incorporation of geophysical data with limited hydrological data may provide valuable information about the stratigraphy, log conductivity values, and the spatial correlation structure of log conductivity, which have traditionally been obtainable only by performing extensive and intrusive hydrological sampling.

  15. Airborne Geophysics and Remote Sensing Applied to Study Greenland Ice Dynamics

    NASA Technical Reports Server (NTRS)

    Csatho, Beata M.

    2003-01-01

    Overview of project: we combined and jointly analysed geophysical, remote sensing and glaciological data for investigating the temporal changes in ice flow and the role of geologic control on glacial drainage. The project included two different studies, the investigation of recent changes of the Kangerlussuaq glacier and the study of geologic control of ice flow in NW Greenland, around the Humboldt, Petermann and Ryder glaciers.

  16. Apparatus and method for automated monitoring of airborne bacterial spores

    NASA Technical Reports Server (NTRS)

    Ponce, Adrian (Inventor)

    2009-01-01

    An apparatus and method for automated monitoring of airborne bacterial spores. The apparatus is provided with an air sampler, a surface for capturing airborne spores, a thermal lysis unit to release DPA from bacterial spores, a source of lanthanide ions, and a spectrometer for excitation and detection of the characteristic fluorescence of the aromatic molecules in bacterial spores complexed with lanthanide ions. In accordance with the method: computer-programmed steps allow for automation of the apparatus for the monitoring of airborne bacterial spores.

  17. Location of Buried Mineshafts and Adits Using Reconnaissance Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Culshaw, Martin; Donnelly, Laurance; McCann, David

    Britain has a long history of mining activity, which stretches back some 3000 years to the excavation of flint in East Anglia. The legacy of this long period of activity is the presence of many buried mineshafts and adits, whose location is often unknown precisely and in many cases not even recorded in historical mining records. As has been shown by Donnelly et al (2003) the discovery of a mineshaft in an area of housing development can have a profound effect on property values in its vicinity. Hence, urgent action must be taken to establish at the site investigation stage of a development to determine whether any mineshafts are present at the site so that remedial action can be taken before construction commences. A study of historical information and the drilling may well enable the developer to locate any suspected mineshafts and adits on his site. However, the use of geophysical reconnaissance methods across the whole site may well provide sufficient information to simplify the drilling programme and reduce its cost to a minimum. In this paper a number of rapid reconnaissance geophysical methods are described and evaluated in terms of their success in the location of buried mineshafts and adits. It has shown that a combination of ground conductivity and magnetic surveys provides a most effective approach on open sites in greenfield and brownfield areas. Ground penetrating radar and micro-gravity surveys have proved to be a valuable approach in urban areas where the use of many geophysical methods is prevented by the presence of various types of cultural noise. On a regional scale the infrared thermography method is being increasingly used but care must be taken to overcome certain environmental difficulties. The practical use of all these geophysical methods in the field is illustrated by a number of appropriate case histories.

  18. Application of geophysical methods for environmental control in mining areas

    SciTech Connect

    Mueller, K.; Muellerova, J.; Hofrichterova, L.

    1994-12-31

    In areas affected by mining operations, a variety of methods ar necessary to acquire information for making decisions related to environmental protection. Of great importance are geophysical methods to collect data about: seismic activity and seismic hazard in the area of interest; radon risk; damage to rock massif resulting from mining operations and development of subsidence depression as mining advances; inhomogeneities in compactness of gangue fills and defects in dams and roadbeds; and hydrodynamic changes and contamination of groundwater. The importance of geophysical methods has increased recently, particularly as applied to monitoring or to the repeatable measurement-variant on fixed points. In the Ostrava-Karvina Coal Basin, a seismic station of the first range OKP was built in 1980. Between 1986 and 1990, the regional diagnostic polygon was established, involving 10 three-component stations uniformly distributed throughout the Ostrava-Karvina Basin that allows seismic activity--both natural and, particularly, that induced by mining operations--to be monitored continuously. Analysis of seismic events related to the advance of mining and to engineering and geological conditions enabled researchers to develop a seismic hazard map for surface facilities. This map is useful for design purposes and for making decisions related to maintenance and damages. Emanation measurements, together with other geophysical methods (e.g., resistivity, seismic, acoustic, and thermic measurements), are utilized to determine stability conditions in the area and to observe development of subsidence depressions and slope deformations. Some of the results from these surveys are given.

  19. Sinkhole Imaging With Multiple Geophysical Methods in Covered Karst Terrain

    NASA Astrophysics Data System (ADS)

    Weiss, M.

    2005-05-01

    A suite of geophysical surveys was run at the Geopark at the University of South Florida campus in Tampa in attempt to determine the degree to which methods could image a collapsed sinkhole with a diameter of ~4m and maximum depth of ~2.5m. Geologically, the Geopark is part of a covered karst terrane, with collapsed sinkholes filled in by overlying unconsolidated sand separated from the weathered limestone beneath by a clayey sand layer. The sinkholes are hydrologically significant as they may serve as sites of concentrated recharge. The methods used during the study include: refraction seismics, resistivity, electromagnetics (TEM and EM), and ground penetrating radar (GPR). Geophysical data are compared against cores. The resistivity, GPR, and seismic refraction profiles yield remarkably consistent images of the clayey sand layer. EM-31 data revealed regional trends in subsurface geology, but could not delineate specific sinkhole features with the desired resolution.

  20. A Research of the Application Geophysical Methods to the Polluted Site and the river bottom mud in Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Cheng, S.; Liu, H. C.

    2013-12-01

    Many site investigations have found that DNAPL is able to penetrate the low permeable layer such as clay or silt-caly layer in subsurface environment. The cumulated DNAPL within the low permeable Layer will gradually diffuse to the high permeable layer to affect he accuracy of investigation and remedial design. As to the deeper zone affected by the penetration of DNAPL, the conventional sampling design investigating only the first unconfined aquifer is no longer suitable for DNAPL investigation. Precisely define the boundary and the distribution of high and low permeable layer is the key to conduct a successful DNAPL investigation. Point information derived from the conventional bore-hole sampling is difficult to be used for locating the DNAPL pollution due to the uncertainty of DNAPL migration and the soluble-phase distribution of the DNAPL partitioned into ground water between the low and high permeable layer. Recently, non-invaded technologies such as geophysical technology have been introduced to provide the plane and space information of pollution in subsurface by integrating few bore-hole dates. The most common used geophysical technologies are ground-penetrating radar method (GPR) and electrical resistivity tomography (ERT). Both methods have their limitations on the pollution investigation when there are interferences exist such as building structure or heavy pavement. A new geophysical technology, geophysical well logging has been developed to overcome above limitations. The information of multi-wells logging could be used to interpret the permeability of subsurface, the dominate flow path and the hot-spot for evaluating the distribution of pollution and the efficiency of remediation in different time sequences. This study would first discuss how DNAPL and its soluble-phase components invade into the low permeable layer based on the field observation. Then, the importance of geophysical technology is introduced with comparing to the limitations of bore

  1. Geophysics-based method of locating a stationary earth object

    DOEpatents

    Daily, Michael R.; Rohde, Steven B.; Novak, James L.

    2008-05-20

    A geophysics-based method for determining the position of a stationary earth object uses the periodic changes in the gravity vector of the earth caused by the sun- and moon-orbits. Because the local gravity field is highly irregular over a global scale, a model of local tidal accelerations can be compared to actual accelerometer measurements to determine the latitude and longitude of the stationary object.

  2. Demonstration of geophysical methods for burial ground geophysical characterization study at the DOE Savannah River site

    SciTech Connect

    Hasbrouck, J.C.; MacLean, H.D.; Geotech, R.

    1996-11-01

    Rust Geotech, operating contractor at the U.S. Department of Energy Grand Junction Projects Office (DOE-GJPO), conducted a demonstration of the trench boundary and large-object location capabilities of five nonintrusive geophysical methods in the Low-Level Radioactive Waste Disposal Facility (LLRWDF) at the DOE Savannah River Site (SRS). The plan for Resource Conservation and Recovery Act (RCRA) closure of the SRS LLRWDF specifies inplace compaction of {open_quotes}B-25{close_quotes} metal boxes containing low-level radioactive wastes. The boxes are buried in Engineered Low-Level Trenches (ELLTs) at the facility. To properly guide and control the compaction operation, the coordinates of the trench boundaries must be determined to an accuracy within 5 feet and the outer edges of the metal boxes in the trenches must be determined to within 2 feet.

  3. 2.5-D modeling in electromagnetic methods of geophysics

    NASA Astrophysics Data System (ADS)

    Tabarovsky, L. A.; Goldman, M. M.; Rabinovich, M. B.; Strack, K.-M.

    1996-10-01

    Understanding, using, or eliminating three-dimensional (3-D) effects in electromagnetic methods of geophysics are critical requirements. Numerous achievements in 3-D modeling sometimes give the impression that they are widely available today in geophysical practice. This is not necessarily true. Existing 3-D modeling packages prove that we know how to perform 3-D modeling. However, the computer resources and costs involved make the practical application of 3-D EM modeling in geophysical applications very limited. A practical compromise, or even alternative, is represented by 2.5-D modeling characterized by the use of a 3-D source in a 2-D medium. This combination allows one to mathematically describe the related boundary value problem as a sequence of independent two-dimensional problems. The typical technique leading to such a split formulation is Fourier analysis. That is why the individual terms of a split solution are often referred to as harmonics. Although each independent problem is two-dimensional, the algorithmic implementation of finite differences or integral equations for the higher harmonics has some specific features not present in the classical 2-D cases. In this paper, a hybrid scheme consisting of a combination of the finite difference technique with the integral equation approach for transient fields is described. Evaluation of algorithm accuracy is presented and a transient logging technique application is considered. The algorithm is fast and easily implemented on a personal computer

  4. Airborne electromagnetic data and processing within Leach Lake Basin, Fort Irwin, California: Chapter G in Geology and geophysics applied to groundwater hydrology at Fort Irwin, California

    USGS Publications Warehouse

    Bedrosian, Paul A.; Ball, Lyndsay B.; Bloss, Benjamin R.

    2014-01-01

    From December 2010 to January 2011, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of Leach Lake Basin within the National Training Center, Fort Irwin, California. These data were collected to characterize the subsurface and provide information needed to understand and manage groundwater resources within Fort Irwin. A resistivity stratigraphy was developed using ground-based time-domain electromagnetic soundings together with laboratory resistivity measurements on hand samples and borehole geophysical logs from nearby basins. This report releases data associated with the airborne surveys, as well as resistivity cross-sections and depth slices derived from inversion of the airborne electromagnetic data. The resulting resistivity models confirm and add to the geologic framework, constrain the hydrostratigraphy and the depth to basement, and reveal the distribution of faults and folds within the basin.

  5. Non-Destructive Survey of Archaeological Sites Using Airborne Laser Scanning and Geophysical Applications

    NASA Astrophysics Data System (ADS)

    Poloprutský, Z.; Cejpová, M.; Němcová, J.

    2016-06-01

    This paper deals with the non-destructive documentation of the "Radkov" (Svitavy district, Czech Republic) archaeological site. ALS, GPR and land survey mapping will be used for the analysis. The fortified hilltop settlement "Radkov" is an immovable historical monument with preserved relics of anthropogenic origin in relief. Terrain reconnaissance can identify several accentuated objects on site. ALS enables identification of poorly recognizable archaeological objects and their contexture in the field. Geophysical survey enables defunct objects identification. These objects are hidden below the current ground surface and their layout is crucial. Land survey mapping provides technical support for ALS and GPR survey. It enables data georeferencing in geodetic reference systems. GIS can then be used for data analysis. M. Cejpová and J. Němcová have studied this site over a long period of time. In 2012 Radkov was surveyed using ALS in the project "The Research of Ancient Road in Southwest Moravia and East Bohemia". Since 2015 the authors have been examining this site. This paper summarises the existing results of the work of these authors. The digital elevation model in the form of a grid (GDEM) with a resolution 1 m of 2012 was the basis for this work. In 2015 the survey net, terrain reconnaissance and GPR survey of two archaeological objects were done at the site. GDEM was compared with these datasets. All datasets were processed individually and its results were compared in ArcGIS. This work was supported by the Grant Agency of the CTU in Prague, grant No. SGS16/063/OHK1/1T/11.

  6. Combination of Geophysical Methods to Support Urban Geological Mapping

    NASA Astrophysics Data System (ADS)

    Gabàs, A.; Macau, A.; Benjumea, B.; Bellmunt, F.; Figueras, S.; Vilà, M.

    2014-07-01

    Urban geological mapping is a key to assist management of new developed areas, conversion of current urban areas or assessment of urban geological hazards. Geophysics can have a pivotal role to yield subsurface information in urban areas provided that geophysical methods are capable of dealing with challenges related to these scenarios (e.g., low signal-to-noise ratio or special logistical arrangements). With this principal aim, a specific methodology is developed to characterize lithological changes, to image fault zones and to delineate basin geometry in the urban areas. The process uses the combination of passive and active techniques as complementary data: controlled source audio-magnetotelluric method (CSAMT), magnetotelluric method (MT), microtremor H/V analysis and ambient noise array measurements to overcome the limitations of traditional geophysical methodology. This study is focused in Girona and Salt surrounding areas (NE of Spain) where some uncertainties in subsurface knowledge (maps of bedrock depth and the isopach maps of thickness of quaternary sediments) need to be resolved to carry out the 1:5000 urban geological mapping. These parameters can be estimated using this proposed methodology. (1) Acoustic impedance contrast between Neogene sediments and Paleogene or Paleozoic bedrock is detected with microtremor H/V analysis that provides the soil resonance frequency. The minimum value obtained is 0.4 Hz in Salt city, and the maximum value is the 9.5 Hz in Girona city. The result of this first method is a fast scanner of the geometry of basement. (2) Ambient noise array constrains the bedrock depth using the measurements of shear-wave velocity of soft soil. (3) Finally, the electrical resistivity models contribute with a good description of lithological changes and fault imaging. The conductive materials (1-100 Ωm) are associated with Neogene Basin composed by unconsolidated detrital sediments; medium resistive materials (100-400 Ωm) correspond to

  7. Dynamics and internal structure of an Alaskan debris-covered glacier from repeat airborne photogrammetry and surface geophysics

    NASA Astrophysics Data System (ADS)

    Holt, John; Levy, Joseph; Petersen, Eric; Larsen, Chris; Fahnestock, Mark

    2016-04-01

    Debris-covered glaciers and rock glaciers encompass a range of compositions and activity, and can be useful paleoclimate indicators. They also respond differently to ongoing climate change than glaciers without a protective cover. Their flow dynamics are not well understood, and their unique surface morphologies, including lobate fronts and arcuate ridges, likely result from viscous flow influenced by a combination of composition, structure, and climatic factors. However, basic connections between flow kinematics and surface morphology have not yet been established, limiting our ability to understand these features. In order to begin to address this problem we have undertaken airborne and surface studies of multiple debris-covered glaciers in Alaska and the western U.S. Sourdough Rock Glacier in the St. Elias Mountains, Alaska, is completely debris-covered and exhibits numerous transverse compressional ridges. Its trunk also exhibits highly regular bumps and swales with a wavelength of ~175 m and amplitudes up to 12 m. In the middle trunk, lineations (boulder trains and furrows) bend around a point roughly 200m from the eastern edge. We acquired five high-resolution airborne surveys of Sourdough Rock Glacier between late 2013 and late 2015 using lidar and photogrammetry to assess annual and seasonal change at the sub-meter level. Differencing the DTMs provides vertical change while feature tracking in orthophotos provide horizontal velocities that indicate meters of annual motion. The flow field is highly correlated with surface features; in particular, compressional ridges in the lower lobe. Stranded, formerly active lobes are also apparent. Surface geophysical studies were undertaken to constrain internal structure and composition using a combination of ground-penetrating radar (GPR) at 50 and 100 MHz in six transects, and time-domain electromagnetic (TDEM) measurements at 47 locations, primarily in an along-flow transect and two cross-flow transects. We infer

  8. Troubleshooting methods for toxicity testing of airborne chemicals in vitro.

    PubMed

    Bakand, Shahnaz; Hayes, Amanda

    2010-01-01

    Toxicology studies of adverse effects induced by inhaled chemicals are technically challenging, due to the requirement of highly controlled experimental conditions needed to achieve reproducible and comparable results. Therefore, many considerations must be fulfilled before adopting in vitro bioassay test systems for toxicity screening of airborne materials. However, recent methodological and technical breakthroughs of in vitro methods have the potential to fulfil the essential requirements of toxicity testing for airborne chemicals. Technology has now become available that allows cells to be cultured on permeable microporous membranes in transwell or snapwell inserts providing a very close contact between target cells and test atmospheres to study the cellular interactions caused by airborne chemical exposures without any interfering culture medium. Using a direct exposure technique at the air-liquid interface, target cells can be continuously exposed to airborne chemicals on their apical side, while being nourished from their basolateral side. Test atmospheres with different physicochemical characteristics such as gases, vapours, solid and liquid aerosols and more recently nanoaerosols, can be delivered into human target cells using static and/or direct dynamic exposure methods. Therefore, toxicological risk assessments of airborne chemicals and even complex atmospheres can be achieved using in vitro test methods in parallel with real-time air monitoring techniques to fulfil the general regulatory requirements of newly developed chemical or pharmaceutical products with the potential for inhalational exposure. In this review current toxicological methods for toxicity testing of inhaled chemicals are presented. Further, to demonstrate the potential application of in vitro methods for studying inhalation toxicity, more advanced exposure techniques developed for toxicity screening of airborne chemicals are discussed.

  9. Multivariate approximation methods and applications to geophysics and geodesy

    NASA Technical Reports Server (NTRS)

    Munteanu, M. J.

    1979-01-01

    The first report in a series is presented which is intended to be written by the author with the purpose of treating a class of approximation methods of functions in one and several variables and ways of applying them to geophysics and geodesy. The first report is divided in three parts and is devoted to the presentation of the mathematical theory and formulas. Various optimal ways of representing functions in one and several variables and the associated error when information is had about the function such as satellite data of different kinds are discussed. The framework chosen is Hilbert spaces. Experiments were performed on satellite altimeter data and on satellite to satellite tracking data.

  10. Expedited Site Characterization geophysics: Geophysical methods and tools for site characterization

    SciTech Connect

    Goldstein, N.E.

    1994-03-01

    This report covers five classes of geophysical technologies: Magnetics; Electrical/electromagnetic; Seismic reflection; Gamma-ray spectrometry; and Metal-specific spectrometry. Except for radiometry, no other classes of geophysical tedmologies are specific for direct detection of the types of contaminants present at the selected sites. For each of the five classes covered, the report gives a general description of the methodology, its field use, and its general applicability to the ESC Project. In addition, the report gives a sample of the most promising instruments available for each class, including the following information: Hardware/software attributes; Purchase and rental costs; Survey rate and operating costs; and Other applicable information based on case history and field evaluations.

  11. Space-time adaptive numerical methods for geophysical applications.

    PubMed

    Castro, C E; Käser, M; Toro, E F

    2009-11-28

    In this paper we present high-order formulations of the finite volume and discontinuous Galerkin finite-element methods for wave propagation problems with a space-time adaptation technique using unstructured meshes in order to reduce computational cost without reducing accuracy. Both methods can be derived in a similar mathematical framework and are identical in their first-order version. In their extension to higher order accuracy in space and time, both methods use spatial polynomials of higher degree inside each element, a high-order solution of the generalized Riemann problem and a high-order time integration method based on the Taylor series expansion. The static adaptation strategy uses locally refined high-resolution meshes in areas with low wave speeds to improve the approximation quality. Furthermore, the time step length is chosen locally adaptive such that the solution is evolved explicitly in time by an optimal time step determined by a local stability criterion. After validating the numerical approach, both schemes are applied to geophysical wave propagation problems such as tsunami waves and seismic waves comparing the new approach with the classical global time-stepping technique. The problem of mesh partitioning for large-scale applications on multi-processor architectures is discussed and a new mesh partition approach is proposed and tested to further reduce computational cost. PMID:19840984

  12. The application of geophysical methods to archaeological prospection

    NASA Astrophysics Data System (ADS)

    Linford, Neil

    2006-07-01

    The aim of this review is to combine the almost universal fascination we share for our past with the comparatively recent, in archaeological terms, application of geophysical prospection methods. For their success, each of these methods relies upon a physical contrast to exist between the buried archaeological feature and the properties of the surrounding subsoil. Understanding the archaeological origin of such physical contrasts, in terms of density, thermal conductivity, electrical resistance, magnetic or dielectric properties, remains fundamental to an appreciation of the discipline. This review provides a broad introduction to the subject area acknowledging the historical development of the discipline and discusses each of the major techniques in turn: earth resistance, magnetic and electromagnetic methods (including ground penetrating radar), together with an appreciation of more esoteric approaches, such as the use of micro-gravity survey to detect buried chambers and voids. The physical principles and field instrumentation involved for the acquisition of data with each method are considered and fully illustrated with case histories of results from the English Heritage archives.

  13. Integration of LANDSAT with geology and airborne geophysics into an operational mineral exploration system. Final report, June 1978 - December 1980

    SciTech Connect

    Lyon, R.J.P.; Crawford, M.F.

    1981-03-01

    Digital data, gamma-ray spectrometry and aeromagnetic data were digitally combined and analyzed for the Bearlodge area (northeastern Wyoming) where potential resources of thorium and rare earths occur. The combined LANDSAT-geophysical data set revealed several geologic structures that were not evident in a single data set for the study area. Both qualitative and quantitative methods of analysis were performed on the combined data sets. Qualitative analysis of the data was done on a computer controlled, interactive color TV display system by overlaying the various data sets in different colors. In the Bearlodge area, this analysis revealed a pair of northwest-southeast tranding lineaments in the LANDSAT image which appeared to truncate a zone of high radioactivity. An elliptical feature formed by drainages is found. An intense thorium-gamma ray anomaly which coincides with thorium-rare earth mineralization, occurs inside this elliptical feature.

  14. Integrated Geophysical Methods Applied to Geotechnical and Geohazard Engineering: From Qualitative to Quantitative Analysis and Interpretation

    NASA Astrophysics Data System (ADS)

    Hayashi, K.

    2014-12-01

    The Near-Surface is a region of day-to-day human activity on the earth. It is exposed to the natural phenomena which sometimes cause disasters. This presentation covers a broad spectrum of the geotechnical and geohazard ways of mitigating disaster and conserving the natural environment using geophysical methods and emphasizes the contribution of geophysics to such issues. The presentation focusses on the usefulness of geophysical surveys in providing information to mitigate disasters, rather than the theoretical details of a particular technique. Several techniques are introduced at the level of concept and application. Topics include various geohazard and geoenvironmental applications, such as for earthquake disaster mitigation, preventing floods triggered by tremendous rain, for environmental conservation and studying the effect of global warming. Among the geophysical techniques, the active and passive surface wave, refraction and resistivity methods are mainly highlighted. Together with the geophysical techniques, several related issues, such as performance-based design, standardization or regularization, internet access and databases are also discussed. The presentation discusses the application of geophysical methods to engineering investigations from non-uniqueness point of view and introduces the concepts of integrated and quantitative. Most geophysical analyses are essentially non-unique and it is very difficult to obtain unique and reliable engineering solutions from only one geophysical method (Fig. 1). The only practical way to improve the reliability of investigation is the joint use of several geophysical and geotechnical investigation methods, an integrated approach to geophysics. The result of a geophysical method is generally vague, here is a high-velocity layer, it may be bed rock, this low resistivity section may contain clayey soils. Such vague, qualitative and subjective interpretation is not worthwhile on general engineering design works

  15. Geophysical site characterization methods -- the ``divining rods`` of the future

    SciTech Connect

    Fieber, L.L.

    1997-12-31

    Have you ever wished that you could use a ``divining rod`` to quickly and reliably define the magnitude of environmental impacts in soil or water? To the uninitiated, such ideas seem like a farfetched script from a star trek episode where a guy named Spock is walking around with a device called a tri-quarter. In realty, such approaches to site characterization have been used in the petroleum and mineral exploration industries for decades. These techniques are so reliable that they are widely used in the medical field today. Consider the value of Magnetic Resonance Imaging (MRI) and Ultrasound. Using the principles of electromagnetics, resistivity, seismology, and gravity, explorationists have successfully measured minute differences in the properties of earth materials. Using these differences, called anomalies, scientists can predict actual conditions with little or no sampling or analysis and with striking repeatability. This paper provides a plain English description of some common geophysical methods in use today. The general principles and specific applications of several methods will be described. The obvious and not-so-obvious limitations of those methods will be examined in detail.

  16. Adaptive mesh refinement and adjoint methods in geophysics simulations

    NASA Astrophysics Data System (ADS)

    Burstedde, Carsten

    2013-04-01

    It is an ongoing challenge to increase the resolution that can be achieved by numerical geophysics simulations. This applies to considering sub-kilometer mesh spacings in global-scale mantle convection simulations as well as to using frequencies up to 1 Hz in seismic wave propagation simulations. One central issue is the numerical cost, since for three-dimensional space discretizations, possibly combined with time stepping schemes, a doubling of resolution can lead to an increase in storage requirements and run time by factors between 8 and 16. A related challenge lies in the fact that an increase in resolution also increases the dimensionality of the model space that is needed to fully parametrize the physical properties of the simulated object (a.k.a. earth). Systems that exhibit a multiscale structure in space are candidates for employing adaptive mesh refinement, which varies the resolution locally. An example that we found well suited is the mantle, where plate boundaries and fault zones require a resolution on the km scale, while deeper area can be treated with 50 or 100 km mesh spacings. This approach effectively reduces the number of computational variables by several orders of magnitude. While in this case it is possible to derive the local adaptation pattern from known physical parameters, it is often unclear what are the most suitable criteria for adaptation. We will present the goal-oriented error estimation procedure, where such criteria are derived from an objective functional that represents the observables to be computed most accurately. Even though this approach is well studied, it is rarely used in the geophysics community. A related strategy to make finer resolution manageable is to design methods that automate the inference of model parameters. Tweaking more than a handful of numbers and judging the quality of the simulation by adhoc comparisons to known facts and observations is a tedious task and fundamentally limited by the turnaround times

  17. Application of high resolution airborne geophysical data in geological modelling of Mohar Cauldron Complex, Bundelkhand Massif, central India: implications for uranium exploration

    NASA Astrophysics Data System (ADS)

    Markandeyulu, A. 13Chaturvedi, A. K. 1Raju, B. V. S. N. 1Parihar, P. S. 1Miller, Roger 2Gooch, Glenn

    2014-03-01

    The Mohar cauldron, located near Mohar village, Shivpuri District, Madhya Pradesh, India, represents an explosive felsic volcanic event. The Mohar Cauldron Complex (MCC) is an important target area for uranium exploration as collapse breccias associated with extensional tectonics are traditionally important for multi-metal deposits, including uranium. Advanced processing and interpretation of the high resolution airborne electromagnetic (AEM), magnetic and radiometric data acquired over the Mohar cauldron and the surrounding environs by Fugro Airborne surveys, successfully mapped the major geological domains in the area based on their distinct geophysical characteristics. Interpretation of the data indicated the presence of three felsic intrusive bodies, only one of which, the MCC, reached the surface and collapsed. Variation in the geophysical characteristics of the three bodies is attributed to variations in hydrothermal alteration. Magnetic signature and radiometric response of the MCC and surrounding area also show signs of intense alteration. AEM data has allowed the boundary of the sediments within the MCC to be mapped accurately, along with the surrounding brecciated zone. Conductivity depth imaging calculated to a depth of 500 m clearly indicated the geometry and disposition of different layers of MCC. 3D voxel modelling of the MCC also allowed for the identification of the different lithologies that constitute the cauldron structure. 3D conductivity isosurfaces provided a thorough understanding of the subsurface distribution of conductivities.

  18. MAGNETOMETRY, SELF-POTENTIAL, AND SEISMIC - ADDITIONAL GEOPHYSICAL METHODS HAVING POTENTIALLY SIGNIFICANT FUTURE UTILIZATION IN AGRICULTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods can provide important information in agricultural settings, and the use of these techniques are becoming more and more widespread. Magnetrometry, self-potential, and seismic are three geophysical methods, all of which have the potential for substantial future use in agriculture, ...

  19. Method of reducing impulsive noise in electromagnetic geophysical data

    SciTech Connect

    Spies, B.R.

    1990-07-31

    This patent describes a method of reducing impulsive noise in electromagnetic geophysical data. It comprises: providing receiving antenna means for receiving an electromagnetic signal. The receiving antenna means receiving impulsive noise; providing noise sensor means for receiving the impulsive noise and placing the noise sensor means so as to receive the impulsive noise that is received by the receiving antenna means and so as to minimize the reception of the electromagnetic signal; simultaneously receiving the electromagnetic signal with the receiving antenna means so as to create a signal record and receiving the impulsive noise with the noise sensor means so as to create a noise record; examining the noise record for occurrences of the impulsive noise by comparing the noise record with a threshold noise value and identifying those instances of time in which the noise record exceeds the threshold; removing those portions of the signal record which are simultaneous with the identified instances in which the noise records exceeds the threshold, wherein the signal record has reduced impulsive noise.

  20. Terrestrial Method for Airborne Lidar Quality Control and Assessment

    NASA Astrophysics Data System (ADS)

    Alsubaie, N. M.; Badawy, H. M.; Elhabiby, M. M.; El-Sheimy, N.

    2014-11-01

    Most of LiDAR systems do not provide the end user with the calibration and acquisition procedures that can use to validate the quality of the data acquired by the airborne system. Therefore, this system needs data Quality Control (QC) and assessment procedures to verify the accuracy of the laser footprints and mainly at building edges. This research paper introduces an efficient method for validating the quality of the airborne LiDAR point clouds data using terrestrial laser scanning data integrated with edge detection techniques. This method will be based on detecting the edge of buildings from these two independent systems. Hence, the building edges are extracted from the airborne data using an algorithm that is based on the standard deviation of neighbour point's height from certain threshold with respect to centre points using radius threshold. The algorithm is adaptive to different point densities. The approach is combined with another innovative edge detection technique from terrestrial laser scanning point clouds that is based on the height and point density constraints. Finally, statistical analysis and assessment will be applied to compare these two systems in term of edge detection extraction precision, which will be a priori step for 3D city modelling generated from heterogeneous LiDAR systems

  1. Geophysical Inversion With Multi-Objective Global Optimization Methods

    NASA Astrophysics Data System (ADS)

    Lelièvre, Peter; Bijani, Rodrigo; Farquharson, Colin

    2016-04-01

    We are investigating the use of Pareto multi-objective global optimization (PMOGO) methods to solve numerically complicated geophysical inverse problems. PMOGO methods can be applied to highly nonlinear inverse problems, to those where derivatives are discontinuous or simply not obtainable, and to those were multiple minima exist in the problem space. PMOGO methods generate a suite of solutions that minimize multiple objectives (e.g. data misfits and regularization terms) in a Pareto-optimal sense. This allows a more complete assessment of the possibilities and provides opportunities to calculate statistics regarding the likelihood of particular model features. We are applying PMOGO methods to four classes of inverse problems. The first are discrete-body problems where the inversion determines values of several parameters that define the location, orientation, size and physical properties of an anomalous body represented by a simple shape, for example a sphere, ellipsoid, cylinder or cuboid. A PMOGO approach can determine not only the optimal shape parameters for the anomalous body but also the optimal shape itself. Furthermore, when one expects several anomalous bodies in the subsurface, a PMOGO inversion approach can determine an optimal number of parameterized bodies. The second class of inverse problems are standard mesh-based problems where the physical property values in each cell are treated as continuous variables. The third class of problems are lithological inversions, which are also mesh-based but cells can only take discrete physical property values corresponding to known or assumed rock units. In the fourth class, surface geometry inversions, we consider a fundamentally different type of problem in which a model comprises wireframe surfaces representing contacts between rock units. The physical properties of each rock unit remain fixed while the inversion controls the position of the contact surfaces via control nodes. Surface geometry inversion can be

  2. EVALUATION OF GEOPHYSICAL METHODS FOR THE DETECTION OF SUBSURFACE TETRACHLOROETHYLENE IN CONTROLLED SPILL EXPERIMENTS

    EPA Science Inventory

    The purpose of the work was to determine the capability of various geophysical methods to detect PCE in the subsurface. Measurements were made with ten different geophysical techniques before, during, and after the PCE injection. This approach provided a clear identification of a...

  3. New geophysical electromagnetic method of archeological object research in Egypt

    NASA Astrophysics Data System (ADS)

    Hachay, O. A.; Khachay, O. Yu.; Attia, Magdi.

    2009-04-01

    The demand to the enhanced geophysical technique and device, in addition to the precise interpretation of the geophysical data, is the resolution of the geophysical complex research, especially by the absence of priory information about the researched place. Therefore, an approach to use the planshet method of electromagnetic induction in the frequency geometry was developed by Hachay. et al., 1997a, 1997b, 1999, 2000, 2002, and 2005. The method was adapted to map and monitor the high complicated geological mediums, to determine the structural factors and criteria of the rock massif in the mine subsurface. The field observation and the way of interpretation make the new technology differ from other known earlier methods of field raying or tomography (Hachay et al., 1997c, 1999, and 2000).The 3D geoelectrical medium research is based on the concept of three staged interpreting of the alternating electromagnetic field in a frame of the block-layered isotropic medium with inclusion (Hachay 1997a, and 2002); in the first stage, the geoelectrical parameters of the horizontal block-layered medium, which includes the heterogeneities, are defined. In the second stage a geometrical model of the different local heterogeneities or groups inside the block-layered medium is constructed based on the local geoelectrical heterogeneities produced from the first stage after filtering the anomalous fields plunged in the medium. While in the third stage, the surfaces of the searched heterogeneities could be calculated in account of the physical parameters of the anomalous objects.For practical realization of that conception the system of observation for alternating electromagnetic field with use of vertical magnetic dipole was elaborated. Such local source of excitation and regular net of observations allows realizing overlapping by different angles of observation directions. As incoming data for interpretation, three components of modules of three components of magnetic field are

  4. Exploration of Tunnel Alignment using Geophysical Methods to Increase Safety for Planning and Minimizing Risk

    NASA Astrophysics Data System (ADS)

    Lehmann, Bodo; Orlowsky, Dirk; Misiek, Rüdiger

    2010-02-01

    Engineering geophysics provides valuable and continuous information for the planning and execution of tunnel construction projects. For geotechnical purposes special high-resolution geophysical methods have been developed during the last decades. The importance of applying geophysical methods in addition to usually used geological and geotechnical exploration techniques is increasing. The main goal is to achieve an accurate and continuous model of the subsurface in a relative short period of operation time. The routine application of engineering geophysical methods will increase in the coming years. Due to the high acceptance of engineering geophysics at construction sites, much wider application of geophysical investigations is expected. The combination of different methods—geophysics, geology, and geotechnics as well as the so-called joint interpretation techniques—will be of essential importance. Engineering geophysics will play an important role during the three phases: geological investigation, tunnel planning, and execution of tunnel construction. If hazards are well known in advance of a tunnel project the safety of workers will essentially be increased and geological risks will be minimized by means of successful and interdisciplinary cooperation.

  5. Exposure to airborne allergens: a review of sampling methods.

    PubMed

    Renström, Anne

    2002-10-01

    A number of methods are used to assess exposure to high-molecular weight allergens. In the occupational setting, airborne dust is often collected on filters using pumps, the filters are eluted and allergen content in the eluate analysed using immunoassays. Collecting inhalable dust using person-carried pumps may be considered the gold standard. Other allergen sampling methods are available. Recently, a method that collects nasally inhaled dust on adhesive surfaces within nasal samplers has been developed. Allergen content can be analysed in eluates using sensitive enzyme immunoassays, or allergen-bearing particles can be immunostained using antibodies, and studied under the microscope. Settling airborne dust can be collected in petri dishes, a cheap and simple method that has been utilised in large-scale exposure studies. Collection of reservoir dust from surfaces using vacuum cleaners with a dust collector is commonly used to measure pet or mite allergens in homes. The sampling methods differ in properties and relevance to personal allergen exposure. Since methods for all steps from sampling to analysis differ between laboratories, determining occupational exposure limits for protein allergens is today unfeasible. A general standardisation of methods is needed.

  6. Geothermal Geophysical Research in Electrical Methods at UURI

    SciTech Connect

    Wannamaker, Philip E.; Wright, Phillip M.

    1992-03-24

    The principal objective of electrical geophysical research at UURI has been to provide reliable exploration and reservoir assessment tools for the shallowest to the deepest levels of interest in geothermal fields. Three diverse methods are being considered currently: magnetotellurics (MT, and CSAMT), self-potential, and borehole resistivity. Primary shortcomings in the methods addressed have included a lack of proper interpretation tools to treat the effects of the inhomogeneous structures often encountered in geothermal systems, a lack of field data of sufficient accuracy and quantity to provide well-focused models of subsurface resistivity structure, and a poor understanding of the relation of resistivity to geothermal systems and physicochemical conditions in the earth generally. In MT, for example, interpretation research has focused successfully on the applicability of 2-D models in 3-D areas which show a preferred structural grain. Leading computer algorithms for 2-D and 3-D simulation have resulted and are combined with modern methods of regularized inversion. However, 3-D data coverage and interpretation is seen as a high priority. High data quality in our own research surveys has been assured by implementing a fully remote reference with digital FM telemetry and real-time processing with data coherence sorting. A detailed MT profile across Long Valley has mapped a caldera-wide altered tuff unit serving as the primary hydrothermal aquifer, and identified a low-resistivity body in the middle crust under the west moat which corresponds closely with teleseismic delay and low density models. In the CSAMT method, our extensive tensor survey over the Sulphur Springs geothermal system provides valuable structural information on this important thermal regime and allows a fundamental analysis of the CSAMT method in heterogeneous areas. The self-potential (SP) method is promoted as an early-stage, cost-effective, exploration technique for covered hydrothermal

  7. Formal methods and digital systems validation for airborne systems

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1993-01-01

    This report has been prepared to supplement a forthcoming chapter on formal methods in the FAA Digital Systems Validation Handbook. Its purpose is as follows: to outline the technical basis for formal methods in computer science; to explain the use of formal methods in the specification and verification of software and hardware requirements, designs, and implementations; to identify the benefits, weaknesses, and difficulties in applying these methods to digital systems used on board aircraft; and to suggest factors for consideration when formal methods are offered in support of certification. These latter factors assume the context for software development and assurance described in RTCA document DO-178B, 'Software Considerations in Airborne Systems and Equipment Certification,' Dec. 1992.

  8. Mapping Ground Water in Three Dimensions - An Analysis of Airborne Geophysical Surveys of the Upper San Pedro River Basin, Cochise County, Southeastern Arizona

    USGS Publications Warehouse

    Wynn, Jeff

    2006-01-01

    This report summarizes the results of two airborne geophysical surveys conducted in the upper San Pedro Valley of southeastern Arizona in 1997 and 1999. The combined surveys cover about 1,000 square kilometers and extend from the Huachuca Mountains on the west to the Mule Mountains and Tombstone Hills on the east and from north of the Babocomari River to near the Mexican border on the south. The surveys included the acquisition of high-resolution magnetic data, which were used to map depth to the crystalline basement rocks underlying the sediments filling the basin. The magnetic inversion results show a complex basement morphology, with sediment thickness in the center of the valley ranging from ~237 meters beneath the city of Sierra Vista to ~1,500 meters beneath Huachuca City and the Palominas area near the Mexican border. The surveys also included acquisition of 60-channel time-domain electromagnetic (EM) data. Extensive quality analyses of these data, including inversion to conductivity vs. depth (conductivity-depth-transform or CDT) profiles and comparisons with electrical well logs, show that the electrical conductor mapped represents the subsurface water-bearing sediments throughout most of the basin. In a few places (notably the mouth of Huachuca Canyon), the reported water table lies above where the electrical conductor places it. These exceptions appear to be due to a combination of outdated water-table information, significant horizontal displacement between the wells and the CDT profiles, and a subtle calibration issue with the CDT algorithm apparent only in areas of highly resistive (very dry) overburden. These occasional disparities appear in less than 5 percent of the surveyed area. Observations show, however, that wells drilled in the thick unsaturated zone along the Huachuca Mountain front eventually intersect water, at which point the water rapidly rises high into the unsaturated zone within the wellbore. This rising of water in a wellbore implies

  9. A method of hidden Markov model optimization for use with geophysical data sets

    NASA Technical Reports Server (NTRS)

    Granat, R. A.

    2003-01-01

    Geophysics research has been faced with a growing need for automated techniques with which to process large quantities of data. A successful tool must meet a number of requirements: it should be consistent, require minimal parameter tuning, and produce scientifically meaningful results in reasonable time. We introduce a hidden Markov model (HMM)-based method for analysis of geophysical data sets that attempts to address these issues.

  10. Investigation of a playa lake bed using geophysical electrical methods

    NASA Astrophysics Data System (ADS)

    Herrmenn, M.; Gurrola, H.; William, R.; Montalvo, R.; Horton, S.; Homberg, J.; Allen, T.; Bribiesca, E.; Lindsey, C.; Anderson, H.; Seshadri, S.; Manns, S.; Hassan, A.; Loren, C.

    2005-12-01

    The 2005 undergraduate applied geophysical class of Texas Tech University conducted a geophysical survey of a playa lake approximately 10 miles northwest of Lubbock Texas. The playa lake is primarily used as grazing land for two llamas and a hand full of sheep, and has been recently used as a dump for broken down sheds and barrels. Our goal was to model the subsurface of the transition from the playa to plains geology and investigate the possible contamination, of the soil and the data, by the metal dumped at the surface. We conducted our survey with and EM31 and homemade D.C. resistivity and SP equipment that allowed students to grasp the theories more clearly. SP readings were collected using clay pots constructed from terracotta pots and copper tubing purchased at the local hardware store and voltage measurements collected with handle held multi-meters. D.C. resistivity data were collected in a dipole-dipole array using 20 nine volt batteries connected in series with a large enough variable resistor and amp meter to regulate steady current flow. A multi meter was used to collect voltage readings. Wenner array data were collected using a home-made multi-filament cable connected switch box to allow a central user to regulate current and take voltage reading. A map of conductivity produced from a 10 m of EM31 reading show that conductivity anomalies mirror topography. The SP profiles show high values in the playa lake that drop off as we move from the clay rich lake bed to normal grassland. Analysis of both the Dipole-Dipole and Wenner array data support a model with 3 flat layers increasing in resistivity with depth. It appears that these remain flat passing beneath the playa and the playa is eroded into these layers.

  11. Agricultural Geophysics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The four geophysical methods predominantly used for agricultural purposes are resistivity, electromagnetic induction, ground penetrating radar (GPR), and time domain reflectometry (TDR). Resistivity and electromagnetic induction methods are typically employed to map lateral variations of apparent so...

  12. Evaluation of airborne geophysical surveys for large-scale mapping of contaminated mine pools: draft final report

    SciTech Connect

    Hammack, R. W.

    2006-12-28

    subtle mine pool anomalies. However, post-survey modeling suggested that thicker, more conductive mine pools might be detected at a more suitable location. The current study sought to identify the best time domain electromagnetic sensor for detecting mine pools and to test it in an area where the mine pools are thicker and more conductive that those in southwestern Virginia. After a careful comparison of all airborne time domain electromagnetic sensors (including both helicopter and fixed-wing systems), the SkyTEM system from Denmark was determined to be the best technology for this application. Whereas most airborne time domain electromagnetic systems were developed to find large, deep, highly conductive mineral deposits, the SkyTEM system is designed for groundwater exploration studies, an application similar to mine pool detection.

  13. Geophysical technique for mineral exploration and discrimination based on electromagnetic methods and associated systems

    DOEpatents

    Zhdanov; Michael S.

    2008-01-29

    Mineral exploration needs a reliable method to distinguish between uneconomic mineral deposits and economic mineralization. A method and system includes a geophysical technique for subsurface material characterization, mineral exploration and mineral discrimination. The technique introduced in this invention detects induced polarization effects in electromagnetic data and uses remote geophysical observations to determine the parameters of an effective conductivity relaxation model using a composite analytical multi-phase model of the rock formations. The conductivity relaxation model and analytical model can be used to determine parameters related by analytical expressions to the physical characteristics of the microstructure of the rocks and minerals. These parameters are ultimately used for the discrimination of different components in underground formations, and in this way provide an ability to distinguish between uneconomic mineral deposits and zones of economic mineralization using geophysical remote sensing technology.

  14. Requirements for airborne vector gravimetry

    NASA Technical Reports Server (NTRS)

    Schwarz, K. P.; Colombo, O.; Hein, G.; Knickmeyer, E. T.

    1992-01-01

    The objective of airborne vector gravimetry is the determination of the full gravity disturbance vector along the aircraft trajectory. The paper briefly outlines the concept of this method using a combination of inertial and GPS-satellite data. The accuracy requirements for users in geodesy and solid earth geophysics, oceanography and exploration geophysics are then specified. Using these requirements, accuracy specifications for the GPS subsystem and the INS subsystem are developed. The integration of the subsystems and the problems connected with it are briefly discussed and operational methods are indicated that might reduce some of the stringent accuracy requirements.

  15. From IGY to IPY, the U.S. Antarctic Oversnow and Airborne Geophysical-Glaciological Research Program from 1957 to 1964 from the View of a Young Graduate Student

    NASA Astrophysics Data System (ADS)

    Behrendt, J. C.

    2006-12-01

    1958 and continuing to 1964 the oversnow traverses were complimented by an airborne geophysical program comprising widely spaced landings for seismic reflection ice sounding and 75,000 km of widely spaced aeromagnetic and snow surface elevation profiles. The airborne profiles were concentrated over the West Antarctic Ice Sheet (WAIS) and along the length of the Transantarctic Mountains, and approximately defined the vast extent of a late Cenozoic volcanic province beneath the WAIS associated with the unknown West Antarctic rift system. There were numerous hazards encountered using these U.S. Navy planes of opportunity including denting a wing on a hidden mountain and a crash on one occasion killing the geophysicist (Edward Thiel) and four others. There was an aircraft death rate of 3.8 deaths per year in the U.S. program from 1955-66. The oversnow and airborne traverses of the IGY-IGC period employed the inductive method of scientific research with only the general objectives of defining the Antarctic Ice Sheet as to surface elevation, thickness, snow accumulation and temperature. In contrast, Antarctic research today employs deductive logic with narrowly defined objectives and testing of hypotheses. This change has been necessary because of expense, and competition of proposals by many scientists. Nonetheless something has been lost by this approach, and there is still the need for "exploration" types of research is the still unknown vast continent of Antarctica.

  16. Multi-method geophysical measurements for soil science investigations in the vadose zone

    NASA Astrophysics Data System (ADS)

    Weihnacht, B.; Börner, F.

    2007-08-01

    We studied the changes of geophysical parameters on a soil wall of the testfield Grenzhof (University of Heidelberg). The unsaturated materials investigated range from coarse-grain gravel to sandy loam. Ground-penetrating radar, ultrasound transmission and complex conductivity measurements were applied as geophysical methods. The measured parameters were used to calculate soil parameters such as porosity, water content, density and grain surface area necessary to obtain geohydraulic parameters such as hydraulic conductivity, field capacity and retention parameters. Soil samples were taken and analysed regarding porosity, apparent density, true density and internal surface. The comparison between petrophysical data from the laboratory and from geophysical measurements showed good correlations for the majority of the data.

  17. Signal analysis and radioholographic methods for airborne radio occultations

    NASA Astrophysics Data System (ADS)

    Wang, Kuo-Nung

    Global Positioning System (GPS) radio occultation (RO) is an atmospheric sounding technique utilizing the change in propagation direction and delay of the GPS signal to measure refractivity, which provides information on temperature and humidity. The GPS-RO technique is now operational on several Low Earth Orbiting (LEO) satellite missions. Nevertheless, when observing localized transient events, such as tropical storms, current LEO satellite systems cannot provide sufficiently high temporal and spatial resolution soundings. An airborne RO (ARO) system has therefore been developed for localized GPS-RO campaigns. The open-loop (OL) tracking in post-processing is used to cross-correlates the received Global Navigation Satellite System (GNSS) signal with an internally generated local carrier signal predicted from a Doppler model and extract the atmospheric refractivity information. OL tracking also allows robust processing of rising GPS signals using backward tracking, which will double the observed occultation event numbers. RO signals in the lower troposphere are adversely affected by rapid phase accelerations and severe signal power fading, however. The negative bias caused by low signal-to-noise ratio (SNR) and multipath ray propagation limits the depth of tracking in the atmosphere. Therefore, we developed a model relating the SNR to the variance in the residual phase of the observed signal produced from OL tracking, and its applicability to airborne data is demonstrated. We then apply this model to set a threshold on refractivity retrieval, based upon the cumulative unwrapping error bias, to determine the altitude limit for reliable signal tracking. To enhance the SNR and decrease the unwrapping error rate, the CIRA-Q climatological model and signal residual phase pre-filtering are utilized to process the ARO residual phase. This more accurately modeled phase and less noisy received signal are shown to greatly reduce the bias caused by unwrapping error at lower

  18. From Mars to Greenland: Charting gravity with space and airborne instruments - Fields, tides, methods, results

    NASA Technical Reports Server (NTRS)

    Colombo, Oscar L. (Editor)

    1992-01-01

    This symposium on space and airborne techniques for measuring gravity fields, and related theory, contains papers on gravity modeling of Mars and Venus at NASA/GSFC, an integrated laser Doppler method for measuring planetary gravity fields, observed temporal variations in the earth's gravity field from 16-year Starlette orbit analysis, high-resolution gravity models combining terrestrial and satellite data, the effect of water vapor corrections for satellite altimeter measurements of the geoid, and laboratory demonstrations of superconducting gravity and inertial sensors for space and airborne gravity measurements. Other papers are on airborne gravity measurements over the Kelvin Seamount; the accuracy of GPS-derived acceleration from moving platform tests; airborne gravimetry, altimetry, and GPS navigation errors; controlling common mode stabilization errors in airborne gravity gradiometry, GPS/INS gravity measurements in space and on a balloon, and Walsh-Fourier series expansion of the earth's gravitational potential.

  19. Multigrid methods and the surface consistent equations of Geophysics

    NASA Astrophysics Data System (ADS)

    Millar, John

    The surface consistent equations are a large linear system that is frequently used in signal enhancement for land seismic surveys. Different signatures may be consistent with a particular dynamite (or other) source. Each receiver and the conditions around the receiver will have different impact on the signal. Seismic deconvolution operators, amplitude corrections and static shifts of traces are calculated using the surface consistent equations, both in commercial and scientific seismic processing software. The system of equations is singular, making direct methods such as Gaussian elimination impossible to implement. Iterative methods such as Gauss-Seidel and conjugate gradient are frequently used. A limitation in the nature of the methods leave the long wavelengths of the solution poorly resolved. To reduce the limitations of traditional iterative methods, we employ a multigrid method. Multigrid methods re-sample the entire system of equations on a more coarse grid. An iterative method is employed on the coarse grid. The long wavelengths of the solutions that traditional iterative methods were unable to resolve are calculated on the reduced system of equations. The coarse estimate can be interpolated back up to the original sample rate, and refined using a standard iterative procedure. Multigrid methods provide more accurate solutions to the surface consistent equations, with the largest improvement concentrated in the long wavelengths. Synthetic models and tests on field data show that multigrid solutions to the system of equations can significantly increase the resolution of the seismic data, when used to correct both static time shifts and in calculating deconvolution operators. The first chapter of this thesis is a description of the physical model we are addressing. It reviews some of the literature concerning the surface consistent equations, and provides background on the nature of the problem. Chapter 2 contains a review of iterative and multigrid methods

  20. Subsurface Cavity Detection by Using Integrated Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Aykaç, Sinem; Rezzan Ozerk, Zeynep; Işıkdeniz Şerifoǧlu, Betül; Bihter Demirci, Büşra; Timur, Emre; Çakir, Korhan

    2016-04-01

    Global warming experienced in recent years in Turkey has led to a severe drought around the Konya Plain in central Anatolia .As a result, excessive amount of ground water was drawn in the region for the sustainability of agricultural activities. So, five small-scale shallow depth sinkholes have occured at different times, at an average interval between 400-450 m. in the study area; Konya-Atlantı. Generally, sinkholes formation occurres among natural processes has turned into disasters caused by humans due to excessive use of groundwater. Consequently, investigations were carried out within a partnership research programme on cavity detection and ground penetration radar, microgravity and multi-frequency electromagnetic methods were jointly utilized. . Exact locations and dimensions of two possible hidden cavities were determined by using these multidisciplinary methods. Keywords: Cavity;Ground-penetrating radar;Konya;Microgravimetry;Multi-frequency electromagnetic method.

  1. Integrated geophysical methods for studying the karst system of Gruta de las Maravillas (Aracena, Southwest Spain)

    NASA Astrophysics Data System (ADS)

    Martínez-Moreno, F. J.; Galindo-Zaldívar, J.; Pedrera, A.; Teixido, T.; Ruano, P.; Peña, J. A.; González-Castillo, L.; Ruiz-Constán, A.; López-Chicano, M.; Martín-Rosales, W.

    2014-08-01

    In this study we contrast the results of different geophysical methods in order to describe the karst system surrounding of the Gruta de las Maravillas cave (Aracena, Spain). A comprehensive study of the geophysical responses of the known cavity was carried out, after which several sections were studied to detect the karst architecture and cave continuity. To ensure precision, the inner 3D-topography of the cave was determined by classical geodetic techniques and a digital terrain model was performed with differential GPS. The microgravity method was used to obtain the residual gravity map of the entire study zone, whose minima could be related to caves. Then, the negative gravity anomalies were analyzed to plan several lines for implementing further geophysical methods: magnetic profiles (MP), electrical resistivity tomography (ERT), induced polarization (IP), 2D seismic prospection (refraction tomography and reflection sections) and ground penetrating radar (GPR). The resulting models for each line explored were integrated with detailed geological maps to establish the unknown continuity of the caves. Finally, we discuss the suitability of each geophysical technique for cave detection in marble with sulfur host rock and propose the best procedures to constrain their geometries.

  2. (Environmental and geophysical modeling, fracture mechanics, and boundary element methods)

    SciTech Connect

    Gray, L.J.

    1990-11-09

    Technical discussions at the various sites visited centered on application of boundary integral methods for environmental modeling, seismic analysis, and computational fracture mechanics in composite and smart'' materials. The traveler also attended the International Association for Boundary Element Methods Conference at Rome, Italy. While many aspects of boundary element theory and applications were discussed in the papers, the dominant topic was the analysis and application of hypersingular equations. This has been the focus of recent work by the author, and thus the conference was highly relevant to research at ORNL.

  3. Joint Geophysical Inversion With Multi-Objective Global Optimization Methods

    NASA Astrophysics Data System (ADS)

    Lelievre, P. G.; Bijani, R.; Farquharson, C. G.

    2015-12-01

    Pareto multi-objective global optimization (PMOGO) methods generate a suite of solutions that minimize multiple objectives (e.g. data misfits and regularization terms) in a Pareto-optimal sense. Providing a suite of models, as opposed to a single model that minimizes a weighted sum of objectives, allows a more complete assessment of the possibilities and avoids the often difficult choice of how to weight each objective. We are applying PMOGO methods to three classes of inverse problems. The first class are standard mesh-based problems where the physical property values in each cell are treated as continuous variables. The second class of problems are also mesh-based but cells can only take discrete physical property values corresponding to known or assumed rock units. In the third class we consider a fundamentally different type of inversion in which a model comprises wireframe surfaces representing contacts between rock units; the physical properties of each rock unit remain fixed while the inversion controls the position of the contact surfaces via control nodes. This third class of problem is essentially a geometry inversion, which can be used to recover the unknown geometry of a target body or to investigate the viability of a proposed Earth model. Joint inversion is greatly simplified for the latter two problem classes because no additional mathematical coupling measure is required in the objective function. PMOGO methods can solve numerically complicated problems that could not be solved with standard descent-based local minimization methods. This includes the latter two classes of problems mentioned above. There are significant increases in the computational requirements when PMOGO methods are used but these can be ameliorated using parallelization and problem dimension reduction strategies.

  4. Evaluation of geophysical methods for the detection of subsurfacetetracgloroethyene in controlled spill experiments

    SciTech Connect

    Mazzella, Aldo; Majer, Ernest L.

    2006-04-10

    A controlled Tetrachloroethylene (PCE) spill experiment was conducted in a multi-layer formation consisting of sand and clayey-sandlayers. The purpose of the work was to determine the detection limits and capability of various geophysical methods. Measurements were made with ten different geophysical techniques before, during, and after the PCE injection. This experiment provided a clear identification of any geophysical anomalies associated with the presence of the PCE. During the injection period all the techniques indicated anomalies associated with the PCE. In order to quantify the results and provide an indication of the PCE detection limits of the various geophysical methods, the tank was subsequently excavated and samples of the various layers were analyzed for residual PCE concentration with gas chromatography (GC). This paper presents some of the results of five of the techniques: cross borehole complex resistivity (CR) also referred to as spectral induced polarization (SIP), cross borehole high resolution seismic (HRS), borehole self potential (SP), surface ground penetration radar (GPR), and borehole video (BV).

  5. Evaluation of surface geophysical methods for collection of hydrogeologic data in the Nebraska Sand Hills region

    USGS Publications Warehouse

    Ellis, M.J.; Hiergesell, R.A.

    1985-01-01

    The practicality of using surface geophysical methods for obtaining geohydrologic data in the Nebraska Sand Hills region was studied during the summer of 1984. Seismic refraction and electrical-resistivity equipment were used, because an evaluation of geohydrologic data indicated that results of surveys made with this equipment probably would yield the most useful data. The study area, which included parts of Garfield, Holt, and Wheeler Counties, was selected because it is geohydrologically representative of the eastern part of the Sand Hills region, and because sufficient geohydrologic data were available for use in evaluating the results of geophysical surveys. Geophysical methods were evaluated for their ability to consistently detect selected geohydrologic horizons. These horizons in descending order, are: the water table, the top of Quaternary silt beds, the top of Quaternary sand and gravel beds , the top of the Tertiary Ogallala Formation, and the top of the Cretaceous Pierre Shale. The top of the Pierre Shale generally is the base of the aquifer, which consists of all of the 500 to 700 ft of overlying deposits. Evaluations of the geophysical data indicate that seismic refraction surveys are best suited for determining the depth to the water table, but are not effective in studying beds below the water table. Vertical electrical soundings provided data on the depth to water table and the top of the silt beds. Available geohydrologic data, however, indicate that with some changes in data collection or interpretation techniques, it may be possible to obtain information on the top of the sand and gravel deposits, the top of the Ogallala Formation, and the top of the Pierre Shale with vertical electrical soundings. Use of either geophysical method could enhance the results of geohydrologic investigations in the Nebraska Sand Hills region. (Author 's abstract)

  6. Modeling and Evaluation of Geophysical Methods for Monitoring and Tracking CO2 Migration

    SciTech Connect

    Daniels, Jeff

    2012-11-30

    Geological sequestration has been proposed as a viable option for mitigating the vast amount of CO{sub 2} being released into the atmosphere daily. Test sites for CO{sub 2} injection have been appearing across the world to ascertain the feasibility of capturing and sequestering carbon dioxide. A major concern with full scale implementation is monitoring and verifying the permanence of injected CO{sub 2}. Geophysical methods, an exploration industry standard, are non-invasive imaging techniques that can be implemented to address that concern. Geophysical methods, seismic and electromagnetic, play a crucial role in monitoring the subsurface pre- and post-injection. Seismic techniques have been the most popular but electromagnetic methods are gaining interest. The primary goal of this project was to develop a new geophysical tool, a software program called GphyzCO2, to investigate the implementation of geophysical monitoring for detecting injected CO{sub 2} at test sites. The GphyzCO2 software consists of interconnected programs that encompass well logging, seismic, and electromagnetic methods. The software enables users to design and execute 3D surface-to-surface (conventional surface seismic) and borehole-to-borehole (cross-hole seismic and electromagnetic methods) numerical modeling surveys. The generalized flow of the program begins with building a complex 3D subsurface geological model, assigning properties to the models that mimic a potential CO{sub 2} injection site, numerically forward model a geophysical survey, and analyze the results. A test site located in Warren County, Ohio was selected as the test site for the full implementation of GphyzCO2. Specific interest was placed on a potential reservoir target, the Mount Simon Sandstone, and cap rock, the Eau Claire Formation. Analysis of the test site included well log data, physical property measurements (porosity), core sample resistivity measurements, calculating electrical permittivity values, seismic data

  7. Simple method for measuring vibration amplitude of high power airborne ultrasonic transducer: using thermo-couple.

    PubMed

    Saffar, Saber; Abdullah, Amir

    2014-03-01

    Vibration amplitude of transducer's elements is the influential parameters in the performance of high power airborne ultrasonic transducers to control the optimum vibration without material yielding. The vibration amplitude of elements of provided high power airborne transducer was determined by measuring temperature of the provided high power airborne transducer transducer's elements. The results showed that simple thermocouples can be used both to measure the vibration amplitude of transducer's element and an indicator to power transmission to the air. To verify our approach, the power transmission to the air has been investigated by other common method experimentally. The experimental results displayed good agreement with presented approach.

  8. Field Demonstrations of Five Geophysical Methods that Could Be Used to Characterize Deposits of Alluvial Aggregate

    USGS Publications Warehouse

    Ellefsen, K.J.; Burton, B.L.; Lucius, J.E.; Haines, S.S.; Fitterman, D.V.; Witty, J.A.; Carlson, D.; Milburn, B.; Langer, W.H.

    2007-01-01

    Personnel from the U.S. Geological Survey and Martin Marietta Aggregates, Inc., conducted field demonstrations of five different geophysical methods to show how these methods could be used to characterize deposits of alluvial aggregate. The methods were time-domain electromagnetic sounding, electrical resistivity profiling, S-wave reflection profiling, S-wave refraction profiling, and P-wave refraction profiling. All demonstrations were conducted at one site within a river valley in central Indiana, where the stratigraphy consisted of 1 to 2 meters of clay-rich soil, 20 to 35 meters of alluvial sand and gravel, 1 to 6 meters of clay, and multiple layers of limestone and dolomite bedrock. All geophysical methods, except time-domain electromagnetic sounding, provided information about the alluvial aggregate that was consistent with the known geology. Although time-domain electromagnetic sounding did not work well at this site, it has worked well at other sites with different geology. All of these geophysical methods complement traditional methods of geologic characterization such as drilling.

  9. Methods to assess airborne concentrations of cotton dust.

    PubMed

    Corn, M

    1987-01-01

    Assessment of concentrations of airborne cotton dust in the factory is necessary to determine adherence to applicable Permissible Exposure Limits (PELs) on a day-to-day basis, as well as for investigatory studies of an epidemiological nature. The latter are required on an ongoing basis to determine the adequacy of PELs to prevent disease in the exposed population. A strategy of sampling includes considerations of the numbers of samples to be obtained for statistical validity and the locations of samples. Current practice is to obtain more "personal samples" of exposure wherever possible, but with regard to cotton dust, instrumentation is not available for such sampling. In the U.S., the vertical elutriator is the instrument of choice for determining the concentrations of cotton dust in air. Results are expressed as milligrams of airborne particulate (cotton dust) per cubic meter. PMID:3434562

  10. Assessment of geothermal energy potential by geophysical methods: Nevşehir Region, Central Anatolia

    NASA Astrophysics Data System (ADS)

    Kıyak, Alper; Karavul, Can; Gülen, Levent; Pekşen, Ertan; Kılıç, A. Rıza

    2015-03-01

    In this study, geothermal potential of the Nevşehir region (Central Anatolia) was assessed by using vertical electrical sounding (VES), self-potential (SP), magnetotelluric (MT), gravity and gravity 3D Euler deconvolution structure analysis methods. Extensive volcanic activity occurred in this region from Upper Miocene to Holocene time. Due to the young volcanic activity Nevşehir region can be viewed as a potential geothermal area. We collected data from 54 VES points along 5 profiles, from 28 MT measurement points along 2 profiles (at frequency range between 320 and 0.0001 Hz), and from 4 SP profiles (total 19 km long). The obtained results based on different geophysical methods are consistent with each other. Joint interpretation of all geological and geophysical data suggests that this region has geothermal potential and an exploration well validated this assessment beyond doubt.

  11. Using computer simulations to teach electrical and electromagnetic methods in applied geophysics

    NASA Astrophysics Data System (ADS)

    Butler, S. L.; Fowlie, C.; Merriam, J.

    2008-12-01

    When teaching geophysics, it is useful to have models that students can investigate in order to develop intuition concerning the physical systems that they are learning about. In recent years, numerical modeling packages have emerged that are sufficiently easy to use that they are suitable for use in undergraduate classroom settings. In this submission, I will describe some examples of the use of computer simulations to enhance student learning in a course on applied geophysics. In some cases, the results of the simulations are compared with the results of analog experiments. Examples of the numerical calculations include simulations of the resistivity method and of the frequency-domain and the time-domain electromagnetic method. I will describe the numerical models used and there results and their effectiveness as a teaching aid.

  12. Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods

    SciTech Connect

    Keating, Kristina; Slater, Lee; Ntarlagiannis, Dimitris; Williams, Kenneth H.

    2015-02-24

    This documents contains the final report for the project "Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods" (DE-SC0007049) Executive Summary: Our research aimed to develop borehole measurement techniques capable of monitoring subsurface processes, such as changes in pore geometry and iron/sulfur geochemistry, associated with remediation of heavy metals and radionuclides. Previous work has demonstrated that geophysical method spectral induced polarization (SIP) can be used to assess subsurface contaminant remediation; however, SIP signals can be generated from multiple sources limiting their interpretation value. Integrating multiple geophysical methods, such as nuclear magnetic resonance (NMR) and magnetic susceptibility (MS), with SIP, could reduce the ambiguity of interpretation that might result from a single method. Our research efforts entails combining measurements from these methods, each sensitive to different mineral forms and/or mineral-fluid interfaces, providing better constraints on changes in subsurface biogeochemical processes and pore geometries significantly improving our understanding of processes impacting contaminant remediation. The Rifle Integrated Field Research Challenge (IFRC) site was used as a test location for our measurements. The Rifle IFRC site is located at a former uranium ore-processing facility in Rifle, Colorado. Leachate from spent mill tailings has resulted in residual uranium contamination of both groundwater and sediments within the local aquifer. Studies at the site include an ongoing acetate amendment strategy, native microbial populations are stimulated by introduction of carbon intended to alter redox conditions and immobilize uranium. To test the geophysical methods in the field, NMR and MS logging measurements were collected before, during, and after acetate amendment. Next, laboratory NMR, MS, and SIP measurements

  13. Geostatistical methods for rock mass quality prediction using borehole and geophysical survey data

    NASA Astrophysics Data System (ADS)

    Chen, J.; Rubin, Y.; Sege, J. E.; Li, X.; Hehua, Z.

    2015-12-01

    For long, deep tunnels, the number of geotechnical borehole investigations during the preconstruction stage is generally limited. Yet tunnels are often constructed in geological structures with complex geometries, and in which the rock mass is fragmented from past structural deformations. Tunnel Geology Prediction (TGP) is a geophysical technique widely used during tunnel construction in China to ensure safety during construction and to prevent geological disasters. In this paper, geostatistical techniques were applied in order to integrate seismic velocity from TGP and borehole information into spatial predictions of RMR (Rock Mass Rating) in unexcavated areas. This approach is intended to apply conditional probability methods to transform seismic velocities to directly observed RMR values. The initial spatial distribution of RMR, inferred from the boreholes, was updated by including geophysical survey data in a co-kriging approach. The method applied to a real tunnel project shows significant improvements in rock mass quality predictions after including geophysical survey data, leading to better decision-making for construction safety design.

  14. Sampling and analysis method for measuring airborne coal dust mass in mixtures with limestone (rock) dust.

    PubMed

    Barone, T L; Patts, J R; Janisko, S J; Colinet, J F; Patts, L D; Beck, T W; Mischler, S E

    2016-01-01

    Airborne coal dust mass measurements in underground bituminous coal mines can be challenged by the presence of airborne limestone dust, which is an incombustible dust applied to prevent the propagation of dust explosions. To accurately measure the coal portion of this mixed airborne dust, the National Institute for Occupational Safety and Health (NIOSH) developed a sampling and analysis protocol that used a stainless steel cassette adapted with an isokinetic inlet and the low temperature ashing (LTA) analytical method. The Mine Safety and Health Administration (MSHA) routinely utilizes this LTA method to quantify the incombustible content of bulk dust samples collected from the roof, floor, and ribs of mining entries. The use of the stainless steel cassette with isokinetic inlet allowed NIOSH to adopt the LTA method for the analysis of airborne dust samples. Mixtures of known coal and limestone dust masses were prepared in the laboratory, loaded into the stainless steel cassettes, and analyzed to assess the accuracy of this method. Coal dust mass measurements differed from predicted values by an average of 0.5%, 0.2%, and 0.1% for samples containing 20%, 91%, and 95% limestone dust, respectively. The ability of this method to accurately quantify the laboratory samples confirmed the validity of this method and allowed NIOSH to successfully measure the coal fraction of airborne dust samples collected in an underground coal mine.

  15. A method for the evaluation of global source and destination characteristics of geophysical data.

    NASA Astrophysics Data System (ADS)

    Pares-Sierra, A.; Flores Morales, A. L.

    2014-12-01

    A method for the global analysis of geophysical data is presented. Using short-period Lagrangeandistances, calculated from a numerical model (ROMS) current data, a stochastictransition matrix is constructed. Iteration methods for this last sparse very large matrix is used to solvestandard Markov chain problem of time of arrival and destination. The method permits theidentification of areas of influence, time of residence and connectivity between regions. Also thecomputation of the selected eigenvectors of the stochastic matrix, using very large sparse systemsmethods, permits the evaluation of global connectivity patterns and global areas of influences.Application for the Gulf of Mexico and the Eastern Tropical Pacific circulation is presented.

  16. GPR survey, as one of the best geophysical methods for social and industrial needs

    NASA Astrophysics Data System (ADS)

    Chernov, Anatolii

    2016-04-01

    This paper is about ways and methods of applying non-invasive geophysical method - Ground penetrating radar (GPR) survey in different spheres of science, industry, social life and culture. Author would like to show that geological methods could be widely used for solving great variety of industrial, human safety and other problems. In that article, we take GPR survey as an example of such useful geophysical methods. It is a fact that investigation of near surface underground medium is important process, which influence on development of different spheres of science and social life: investigation of near surface geology (layering, spreading of rock types, identification of voids, etc.), hydrogeology (depth to water horizons, their thickness), preparation step for construction of roads and buildings (civil geology, engineering geology), investigation of cultural heritage (burial places, building remains,...), ecological investigations (land slides, variation in underground water level, etc.), glaciology. These tasks can be solved by geological methods, but as usual, geophysical survey takes a lot of time and energy (especially electric current and resistivity methods, seismic survey). Author claims that GPR survey can be performed faster than other geophysical surveys and results of GPR survey are informative enough to make proper conclusions. Some problems even cannot be solved without GPR. For example, identification of burial place (one of author's research objects): results of magnetic and electric resistivity tomography survey do not contain enough information to identify burial place, but according to anomalies on GPR survey radarograms, presence of burial place can be proven. Identification of voids and non-magnetic objects also hardly can be done by another non-invasive geophysics surveys and GPR is applicable for that purpose. GPR can be applied for monitoring of dangerous processes in geological medium under roads, buildings, parks and other places of human

  17. The Continuous wavelet in airborne gravimetry

    NASA Astrophysics Data System (ADS)

    Liang, X.; Liu, L.

    2013-12-01

    Airborne gravimetry is an efficient method to recover medium and high frequency band of earth gravity over any region, especially inaccessible areas, which can measure gravity data with high accuracy,high resolution and broad range in a rapidly and economical way, and It will play an important role for geoid and geophysical exploration. Filtering methods for reducing high-frequency errors is critical to the success of airborne gravimetry due to Aircraft acceleration determination based on GPS.Tradiontal filters used in airborne gravimetry are FIR,IIR filer and so on. This study recommends an improved continuous wavelet to process airborne gravity data. Here we focus on how to construct the continuous wavelet filters and show their working principle. Particularly the technical parameters (window width parameter and scale parameter) of the filters are tested. Then the raw airborne gravity data from the first Chinese airborne gravimetry campaign are filtered using FIR-low pass filter and continuous wavelet filters to remove the noise. The comparison to reference data is performed to determinate external accuracy, which shows that continuous wavelet filters applied to airborne gravity in this thesis have good performances. The advantages of the continuous wavelet filters over digital filters are also introduced. The effectiveness of the continuous wavelet filters for airborne gravimetry is demonstrated through real data computation.

  18. New Methods for Personal Exposure Monitoring for Airborne Particles

    PubMed Central

    Koehler, Kirsten A.; Peters, Thomas

    2016-01-01

    Airborne particles have been associated with a range of adverse cardiopulmonary outcomes, which has driven its monitoring at stationary, central sites throughout the world. Individual exposures, however, can differ substantially from concentrations measured at central sites due to spatial variability across a region and sources unique to the individual, such as cooking or cleaning in homes, traffic emissions during commutes, and widely varying sources encountered at work. Personal monitoring with small, battery-powered instruments enables the measurement of an individual’s exposure as they go about their daily activities. Personal monitoring can substantially reduce exposure misclassification and improve the power to detect relationships between particulate pollution and adverse health outcomes. By partitioning exposures to known locations and sources, it may be possible to account for variable toxicity of different sources. This review outlines recent advances in the field of personal exposure assessment for particulate pollution. Advances in battery technology have improved the feasibility of 24-hour monitoring, providing the ability to more completely attribute exposures to microenvironment (e.g., work, home, commute). New metrics to evaluate the relationship between particulate matter and health are also being considered, including particle number concentration, particle composition measures, and particle oxidative load. Such metrics provide opportunities to develop more precise associations between airborne particles and health and may provide opportunities for more effective regulations. PMID:26385477

  19. 3D modelling of the electromagnetic response of geophysical targets using the FDTD method

    SciTech Connect

    Debroux, P.S.

    1996-05-01

    A publicly available and maintained electromagnetic finite-difference time domain (FDTD) code has been applied to the forward modelling of the response of 1D, 2D and 3D geophysical targets to a vertical magnetic dipole excitation. The FDTD method is used to analyze target responses in the 1 MHz to 100 MHz range, where either conduction or displacement currents may have the controlling role. The response of the geophysical target to the excitation is presented as changes in the magnetic field ellipticity. The results of the FDTD code compare favorably with previously published integral equation solutions of the response of 1D targets, and FDTD models calculated with different finite-difference cell sizes are compared to find the effect of model discretization on the solution. The discretization errors, calculated as absolute error in ellipticity, are presented for the different ground geometry models considered, and are, for the most part, below 10% of the integral equation solutions. Finally, the FDTD code is used to calculate the magnetic ellipticity response of a 2D survey and a 3D sounding of complicated geophysical targets. The response of these 2D and 3D targets are too complicated to be verified with integral equation solutions, but show the proper low- and high-frequency responses.

  20. Combining geophysical methods for the observation of hydrological processes at the hillslope-scale

    NASA Astrophysics Data System (ADS)

    Martini, E.; Kögler, S.; Dierke, C.; Wollschlaeger, U.; Werban, U.; Behrens, T.; Schmidt, K.; Dietrich, P.; Zacharias, S.

    2012-12-01

    Knowledge of soil moisture dynamics beyond the point scale is of crucial importance e.g. for water management, hydrological studies, and for calibration and validation of soil water balance models. There is a clear need for robust and flexible monitoring technologies that are able to capture high resolution information over large areas. Fast, precise, and ideally in-situ, measurements may be obtained from geophysical surveys and distributed in-situ wireless soil moisture sensor networks. In the Harz Mountains (Central Germany), a 2.5 ha hillslope was chosen as study site, to be monitored using a wireless sensor network, consisting of Time-Domain Transmission (TDT) sensors, that are able to measure soil water content and, in addition, soil temperature. Along the hillslope, pedological features are correlated with topography, and lateral flows are expected to be a relevant component of the runoff process. The aim of the work is (i) to test and validate geophysical platforms at the small-catchment scale in terms of technological improvement and suitability for hydrological studies; (ii) to design spatially optimized monitoring strategies using geophysical methods; (iii) to validate soil moisture estimation using geophysical methods. For the preliminary study, a larger area of the catchment (144 ha in size) was investigated using three electromagnetical induction (EMI) sensors (EM38-DD, EM38-MK2 and EM31-MK2, Geonics Ltd., Canada) and a gamma-ray spectrometer (GF Instruments, Czech Republic).On the hillslope, time-lapse EMI data were collected, and measurements will be repeated in future surveys to monitor patterns in electrical conductivity of soil that are related to changes in the soil moisture content. Based on these data, a Latin Hypercube Sampling strategy (LHS) was applied to provide 30 sampling points for the soil moisture monitoring network. In order to intensify the observations at shorter distances, 10 additional points were added to the network. Before the

  1. Assessment of an ancient bridge combining geophysical and advanced photogrammetric methods: Application to the Pont De Coq, France

    NASA Astrophysics Data System (ADS)

    Fauchard, Cyrille; Antoine, Raphaël; Bretar, Frédéric; Lacogne, Julien; Fargier, Yannick; Maisonnave, Cindy; Guilbert, Vincent; Marjerie, Pierre; Thérain, Paul-Franck; Dupont, Jean-Paul; Pierrot-Deseilligny, Marc

    2013-11-01

    A high resolution geophysical survey was carried out on the Pont De Coq, a medieval stone arch bridge located in Normandy (France) in 2011 and 2012. Two complementary methods are used: Electrical Resistivity Tomography (ERT) and Ground PenetratingRadar (GPR). They allow to evaluate the structural state of the bridge and to characterize the subsurface around and beneath the bridge. An excellent correlation is obtained between the geophysical methods and the geological data obtained around the bridge. In order to improve the restitution of the geophysical data, an advanced photogrammetric method is performed, providing a high resolution 3D Digital Terrain Model (DTM) of the Pont de Coq. The advanced photogrammetry enhances the presentation of the GPR and ERT data. This approach is an easy-to-use, rapid and cost-effective tool for stakeholders. Finally, it is a promising and original method for improved interpretations of future geophysical surveys.

  2. Comparison of different hand-drying methods: the potential for airborne microbe dispersal and contamination.

    PubMed

    Best, E L; Redway, K

    2015-03-01

    Efficient washing and drying of hands is important in prevention of the transfer of micro-organisms. However, knowledge surrounding the potential for microbial contamination according to hand-drying methods is limited. This study assessed the potential for airborne microbe dispersal during hand drying by four methods (paper towels, roller towel, warm air and jet air dryer) using three different models. The jet air dryer dispersed liquid from users' hands further and over a greater range (up to 1.5m) than the other drying methods (up to 0.75 m), demonstrating the differing potential risks for airborne microbe dissemination, particularly if handwashing is suboptimal. PMID:25586988

  3. Method for measuring the size distribution of airborne rhinovirus

    SciTech Connect

    Russell, M.L.; Goth-Goldstein, R.; Apte, M.G.; Fisk, W.J.

    2002-01-01

    About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber. Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor.

  4. Geochemical Characterization Using Geophysical Data and Markov Chain Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Chen, J.; Hubbard, S.; Rubin, Y.; Murray, C.; Roden, E.; Majer, E.

    2002-12-01

    if they were available from direct measurements or as variables otherwise. To estimate the geochemical parameters, we first assigned a prior model for each variable and a likelihood model for each type of data, which together define posterior probability distributions for each variable on the domain. Since the posterior probability distribution may involve hundreds of variables, we used a Markov Chain Monte Carlo (MCMC) method to explore each variable by generating and subsequently evaluating hundreds of realizations. Results from this case study showed that although geophysical attributes are not necessarily directly related to geochemical parameters, geophysical data could be very useful for providing accurate and high-resolution information about geochemical parameter distribution through their joint and indirect connections with hydrogeological properties such as lithofacies. This case study also demonstrated that MCMC methods were particularly useful for geochemical parameter estimation using geophysical data because they allow incorporation into the procedure of spatial correlation information, measurement errors, and cross correlations among different types of parameters.

  5. Efficiency of Pareto joint inversion of 2D geophysical data using global optimization methods

    NASA Astrophysics Data System (ADS)

    Miernik, Katarzyna; Bogacz, Adrian; Kozubal, Adam; Danek, Tomasz; Wojdyła, Marek

    2016-04-01

    Pareto joint inversion of two or more sets of data is a promising new tool of modern geophysical exploration. In the first stage of our investigation we created software enabling execution of forward solvers of two geophysical methods (2D magnetotelluric and gravity) as well as inversion with possibility of constraining solution with seismic data. In the algorithm solving MT forward solver Helmholtz's equations, finite element method and Dirichlet's boundary conditions were applied. Gravity forward solver was based on Talwani's algorithm. To limit dimensionality of solution space we decided to describe model as sets of polygons, using Sharp Boundary Interface (SBI) approach. The main inversion engine was created using Particle Swarm Optimization (PSO) algorithm adapted to handle two or more target functions and to prevent acceptance of solutions which are non - realistic or incompatible with Pareto scheme. Each inversion run generates single Pareto solution, which can be added to Pareto Front. The PSO inversion engine was parallelized using OpenMP standard, what enabled execution code for practically unlimited amount of threads at once. Thereby computing time of inversion process was significantly decreased. Furthermore, computing efficiency increases with number of PSO iterations. In this contribution we analyze the efficiency of created software solution taking under consideration details of chosen global optimization engine used as a main joint minimization engine. Additionally we study the scale of possible decrease of computational time caused by different methods of parallelization applied for both forward solvers and inversion algorithm. All tests were done for 2D magnetotelluric and gravity data based on real geological media. Obtained results show that even for relatively simple mid end computational infrastructure proposed solution of inversion problem can be applied in practice and used for real life problems of geophysical inversion and interpretation.

  6. Methods and spatial extent of geophysical Investigations, Mono Lake, California, 2009 to 2011

    USGS Publications Warehouse

    Jayko, A.S.; Hart, P.E.; Childs, J. R.; Cormier, M.-H.; Ponce, D.A.; Athens, N.D.; McClain, J.S.

    2013-01-01

    This report summarizes the methods and spatial extent of geophysical surveys conducted on Mono Lake and Paoha Island by U.S. Geological Survey during 2009 and 2011. The surveys include acquisition of new high resolution seismic reflection data, shipborne high resolution magnetic data, and ground magnetic and gravity data on Paoha Island. Several trials to acquire swath bathymetry and side scan sonar were conducted, but were largely unsuccessful likely due to physical properties of the water column and (or) physical properites of the highly organic bottom sediment.

  7. Altimeter crossover methods for precision orbit determination and the mapping of geophysical parameters

    NASA Technical Reports Server (NTRS)

    Shum, C. K.; Schutz, B. E.; Tapley, B. D.; Zhang, B. H.

    1990-01-01

    Accurate orbit determination and the recovery of geophysical parameters are presently attempted via methodologies which use differenced height measurements at the points where the ground tracks of the altimetric satellite orbits intersect. Such 'crossover measurements' could significantly improve the earth's gravity field model. Attention is given to a novel technique employing crossover measurements from two satellites carrying altimeter instruments; this method can observe zonal harmonics of the earth's geopotential which are weakly observed through single-satellite crossovers. This dual-satellite crossover technique will be applicable to data from such future oceanographic satellites as ERS-1.

  8. Preclosure monitoring and performance confirmation at Yucca Mountain: Applicability of geophysical, geohydrological, and geochemical methods

    SciTech Connect

    Tsang, C.F.

    1989-06-01

    The present paper presents considerations on studies that would be required for preclosure monitoring and performance confirmation of a nuclear waste geologic repository in an unsaturated zone. The critical parameters that should be monitored are reviewed and two scales of measurement relevant to monitoring activities, room scale and repository scale, are taken as a framework for investigation. A number of monitoring methods based on geophysics, geohydrology, and geochemistry are briefly summarized for their potential usefulness for preclosure monitoring and performance confirmation of the geologic repository. Particular emphasis is given to measurement of the spatial distribution of parameters in contrast to single-point measurements of quantities. 12 refs., 1 fig., 1 tab.

  9. Geophysical Monitoring Methods Evaluation for the FutureGen 2.0 Project

    SciTech Connect

    Strickland, Chris E.; USA, Richland Washington; Vermeul, Vince R.; USA, Richland Washington; Bonneville, Alain; USA, Richland Washington; Sullivan, E. Charlotte; USA, Richland Washington; Johnson, Tim C.; USA, Richland Washington; Spane, Frank A.; USA, Richland Washington; Gilmore, Tyler J.; USA, Richland Washington

    2014-12-31

    A comprehensive monitoring program will be needed in order to assess the effectiveness of carbon sequestration at the FutureGen 2.0 carbon capture and storage (CCS) field-site. Geophysical monitoring methods are sensitive to subsurface changes that result from injection of CO2 and will be used for: (1) tracking the spatial extent of the free phase CO2 plume, (2) monitoring advancement of the pressure front, (3) identifying or mapping areas where induced seismicity occurs, and (4) identifying and mapping regions of increased risk for brine or CO2 leakage from the reservoir. Site-specific suitability and cost effectiveness were evaluated for a number of geophysical monitoring methods including: passive seismic monitoring, reflection seismic imaging, integrated surface deformation, time-lapse gravity, pulsed neutron capture logging, cross-borehole seismic, electrical resistivity tomography, magnetotellurics and controlled source electromagnetics. The results of this evaluation indicate that CO2 injection monitoring using reflection seismic methods would likely be difficult at the FutureGen 2.0 site. Electrical methods also exhibited low sensitivity to the expected CO2 saturation changes and would be affected by metallic infrastructure at the field site. Passive seismic, integrated surface deformation, time-lapse gravity, and pulsed neutron capture monitoring were selected for implementation as part of the FutureGen 2.0 storage site monitoring program.

  10. Geophysical Monitoring Methods Evaluation for the FutureGen 2.0 Project

    DOE PAGES

    Strickland, Chris E.; USA, Richland Washington; Vermeul, Vince R.; USA, Richland Washington; Bonneville, Alain; USA, Richland Washington; Sullivan, E. Charlotte; USA, Richland Washington; Johnson, Tim C.; USA, Richland Washington; et al

    2014-12-31

    A comprehensive monitoring program will be needed in order to assess the effectiveness of carbon sequestration at the FutureGen 2.0 carbon capture and storage (CCS) field-site. Geophysical monitoring methods are sensitive to subsurface changes that result from injection of CO2 and will be used for: (1) tracking the spatial extent of the free phase CO2 plume, (2) monitoring advancement of the pressure front, (3) identifying or mapping areas where induced seismicity occurs, and (4) identifying and mapping regions of increased risk for brine or CO2 leakage from the reservoir. Site-specific suitability and cost effectiveness were evaluated for a number ofmore » geophysical monitoring methods including: passive seismic monitoring, reflection seismic imaging, integrated surface deformation, time-lapse gravity, pulsed neutron capture logging, cross-borehole seismic, electrical resistivity tomography, magnetotellurics and controlled source electromagnetics. The results of this evaluation indicate that CO2 injection monitoring using reflection seismic methods would likely be difficult at the FutureGen 2.0 site. Electrical methods also exhibited low sensitivity to the expected CO2 saturation changes and would be affected by metallic infrastructure at the field site. Passive seismic, integrated surface deformation, time-lapse gravity, and pulsed neutron capture monitoring were selected for implementation as part of the FutureGen 2.0 storage site monitoring program.« less

  11. Applied geophysics

    SciTech Connect

    Dohr, G.

    1981-01-01

    This book discusses techniques which play a predominant role in petroleum and natural gas exploration. Particular emphasis has been placed on modern seismics which today claims over 90% of man-power and financial resources in exploration. The processing of geophysical data is the most important factor in applied physics and emphasis is placed on it in the discussion of exploration problems. Chapter titles include: refraction seismics; reflection seismics; seismic field techniques; digital seismics-electronic data processing; digital seismics-practical application; recent developments, special seismic procedures; gravitational methods; magnetic methods; geoelectric methods; well-logging; and miscellaneous methods in applied geophysics (thermal methods, radioactive dating, natural radioactivity surveys, and surface detection of gas. (DMC)

  12. Integrated Analysis of Airborne Geophysical Data to Understand the Extent, Kinematics and Tectonic Evolution of the Precambrian Aswa Shear Zone in East Africa.

    NASA Astrophysics Data System (ADS)

    Katumwehe, A. B.; Atekwana, E. A.; Abdelsalam, M. G.; Laó-Dávila, D. A.

    2014-12-01

    The Aswa Shear zone (ASZ) is a Precambrian lithospheric structure which forms the western margin of the East African Orogeny (EAO) that influenced the evolution of many tectonic events in Eastern Africa including the East African Rift System. It separates the cratonic entities of Saharan Metacraton in the northeast from the Congo craton and the Tanzanian craton and the Kibaran orogenic belt to the southwest. However little is known about its kinematics and the extent and tectonic origin are not fully understood. We developed a new technique based on the tilt method to extract kinematic information from high-resolution airborne magnetic data. We also used radiometric data over Uganda integrated with Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) in South Sudan to understand the extent, kinematics and define the tectonic origin of ASZ. (1) Our results suggest that the ASZ extends in a NW-SE for ~550 km in Uganda and South Sudan. (2) The airborne magnetic and radiometric data revealed a much wider (~50 km) deformation belt than the mapped 5-10 km of exposed surface expression of the ASZ. The deformation belt associated with the shear is defined by three NW-trending sinistral strike-slip shear zones bounding structural domains with magnetic fabrics showing splays of secondary shear zones and shear-related folds. These folds are tighter close to the discrete shear zones with their axial traces becoming sub-parallel to the shear zones. Similar fold patterns are observed from South Sudan in the SRTM DEM. We interpret these folds as due to ENE-WSW shortening associated with the sinistral strike-slip movement. (3) To the northeast of the shear zone, the magnetic patterns suggest a series of W-verging nappes indicative of strong E-W oriented shortening. Based on the above observations, we relate the evolution of the ASZ to Neoproterozoic E-W collision between East and West Gondwana. This collision produced E-W contraction resulting in W-verging thrusts

  13. EVALUATION OF THREE CLEANING METHODS FOR REMOVING ASBESTOS FROM CARPET. DETERMINATION OF AIRBORNE ASBESTOS CONCENTRATIONS ASSOCIATED WITH EACH METHOD

    EPA Science Inventory

    This study was conducted to compare the effectiveness of three cleaning methods to remove asbestos from contaminated carpet and to determine the airborne asbestos concentrations associated with the use of each method. The carpet on which the methods were tested was naturally cont...

  14. A simple method for vignette correction of airborne digital camera data

    SciTech Connect

    Nguyen, A.T.; Stow, D.A.; Hope, A.S.

    1996-11-01

    Airborne digital camera systems have gained popularity in recent years due to their flexibility, high geometric fidelity and spatial resolution, and fast data turn-around time. However, a common problem that plagues these types of framing systems is vignetting which causes falloff in image brightness away from principle nadir point. This paper presents a simple method for vignetting correction by utilizing laboratory images of a uniform illumination source. Multiple lab images are averaged and inverted to create digital correction templates which then are applied to actual airborne data. The vignette correction was effective in removing the systematic falloff in spectral values. We have shown that the vignette correction is a necessary part of the preprocessing of raw digital airborne remote sensing data. The consequences of not correcting for these effects are demonstrated in the context of monitoring of salt marsh habitat. 4 refs.

  15. Handbook of Agricultural Geophysics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods continue to show great promise for use in agriculture. The term “agricultural geophysics” denotes a subdiscipline of geophysics that is focused only on agricultural applications. The Handbook of Agricultural Geophysics was compiled to include a comprehensive overview of the geoph...

  16. Neotectonic implications by geophysical surveys of topographic features identified by Airborne Laser Scanning in the Neusiedlersee/Ferto area (Austria/Hungary)

    NASA Astrophysics Data System (ADS)

    Timár, G.; Székely, B.; Zámolyi, A.; Houseman, G.; Stuart, G.; Grasemann, B.; Dombrádi, E.; Galsa, A.; Spahic, D.; Draganits, E.

    2009-04-01

    The area around the Lake Neudsiedlersee (Lake Fertő in Hungarian) was analysed to understand its neotectonic activity and gather possible explanations of the features of the topography and microtopography. The area consists of two, considerably different parts in terms of topography and geomorphology. The western and north-western shores of the lake are connected to the Leitha Mts., a low ridge (its relative height is about 300 meters) that connects the Alpine orogen in the SW with the Carpathians to NE bounded by active strike-slip faulting. In this part of the area, several outcrops were investigated, of which the one at St. Margarethen was systematically measured by multielectric sounding and GPR, and an other one at St. Georgen, north of Eisenstadt, was used for auxiliary data gathering. The eastern and southern shores, belonging to the Pannonian Basin, are mostly flatlands, parts of the Little Hungarian Plain with extremely low relief and no real natural drainage. The small variations of the surface altitude (less than ten meters), referred to as microtopography here, are due to elongated ridges and extremely shallow perennial or temporal playa lakes. In order to understand better the subsurface structure, a multimethod approach has been applied. Geophysical survey methods (vertical electric sounding, land seismics, gravity measurements) were carried out to describe the layer structure of this area, especially a zone, north of Illmitz, connected to interesting elements of microtopography. The identification of microtopographic features were carried out using high resolution digital elevation datasets, derived from Aerial Laser Scannings (ALS). Seismic measurements were carried out also in the lake itself to understand the structural geological settings of the lake bottom to the depth of ca. 50 meters. All of these measurements were made in the framework of a common student fieldwork of the Eötvös University, the University of Leeds and the University of

  17. Assessing subsurface strata using geophysical and geotechnical methods for designing structures near ground cracks

    NASA Astrophysics Data System (ADS)

    AlFouzan, F.; Dafalla, M.; Mutaz, E.

    2012-04-01

    This paper presents a combined approach using both geophysical and geotechnical approaches to study and evaluate the subsurface strata near ground for sites suffering from faults and cracks. It demonstrates how both techniques can be utilized to gather useful information for design geotechnical engineers. The safe distance for construction close to a ground crack is mainly dependant on the subsurface stratification and the engineering properties of underlying soils or rocks. Other factors include the area geology and concepts of safety margins. This study is carried out for a site in Al-Qassim region, Saudi Arabia. This type of faults and cracks can normally occur due to a geological or physical event or due to the nature and properties of the subsurface material. The geotechnical works included advancing rotary boreholes to depths of 25m to 31m with sampling and testing. The geophysical method used included performing 2D electrical resistivity profiles. The results of geophysical and geotechnical works showed good and close agreement. The use of 2D electrical resistivity was found useful to establish the layer thicknesses of shale and highly plastic clay. This cannot be determined without deep and expensive direct boring investigation. The results showed that a thick layer of expansive soil, which is considered a high-risk soil type containing large percentage of highly plastic clay materials, underlies the site. The volume changes due to humidity variations can result in either swelling or shrinking. These changes can have significant impact on engineering structures such as light buildings and roads. The logic of placing structures in close vicinity of the cracks is based on lateral stresses exerted on the crack face. The layer thickness is a detrimental factor to establish a safe design distance. Stress distribution analysis procedure is explained.

  18. Hidden gully erosion - detection and characterization of piping systems using geomorphological and geophysical methods (GPR, ERT)

    NASA Astrophysics Data System (ADS)

    Bernatek-Jakiel, Anita; Kondracka, Marta

    2016-04-01

    The significance of piping in gully formation and hillslope hydrology has been discussed for many years. However, piping as a subsurface erosion caused by water flowing through the soil is still considered as one of the most difficult erosion processes to study, because it occurs below the soil surface and traces of piping become visible on the surface only when a pipe roof collapses, or a pipe inlet or a pipe outlet has been located. Detection of pipes and their complex characterization is still a methodological challenge. Therefore, this study aims at a better detection and characterization of piping systems in a mountainous area under a temperate climate using geomorphological mapping and geophysical methods (ground penetrating radar and electrical resistivity tomography). The survey was carried out in the Bereźnica Wyżna catchment, in the Bieszczady Mts. (Eastern Carpathians, Poland), where pipes develop in Cambisols at a depth ranging from ca 0.70 to 1.00 m. The geomorphological mapping was carried out in the in the whole catchment (2.96 km2), whereas the geophysical survey was limited to two zones (zone A - ca 32 x 82 m, zone B - ca 58 x 115 m). In this study a standard RAMAC GPR system (Malå GeoScience) with shielded 500 MHz antenna was used. The electrical resistivity tomography (ERT) was performed using electrical imaging system LUND with Terrameter SAS 4000 produced by company ABEM. The ERT and GPR data were interpreted in the RES2DINV (Geotomo Software) and RadExplorer software (DECO Geophysical Ltd) respectively. In total, 3 longitudinal and 26 transverse GPR profiles and five ERTs were performed. The used geophysical techniques are shown to be successful in identifying pipes tested in the pilot catchment. Pipes identified by GPR and ERT were verified by the surface indicators (i.e. lowering of surface above pipes). The GPR and ERT applications suggest that piping systems density is much greater than could be detected from surface observation alone

  19. REVIEW OF GEOPHYSICAL METHODS USED FOR CHARACTERIZING BRINE POCKETS AT THE WASTE ISOLATION PILOT PLANT

    NASA Astrophysics Data System (ADS)

    Ghose, S. N.

    2009-12-01

    The Waste Isolation Pilot Pant (WIPP) is a deep geologic repository built and operated by the US Department of Energy (DOE) for disposal of radioactive transuranic waste. The repository is located in the southeastern part of New Mexico at 658.5 m from the surface in the bedded salt deposit (Salado Formation) of the Delaware Basin. Pressurized brine reservoirs were encountered while drilling (1mile north) into the Castile Formation which underlies the WIPP repository. Typically these pockets are located below 1000m which precludes use of high resolution surface geophysical methods. The operator decided to use direct borehole logging and time domain electromagnetic induction method (TDEM) to characterize the possible existence of brine pockets under the WIPP underground workings. The scope of the present review is limited to TDEM analysis only. The geophysical loggings of boreholes are an integral part of subsurface drilling and provide isolated point-samples of the drilled interior. The geophysical logs are typically records of the electrical properties (resistivity logs) of the subsurface strata and logging process is relatively more direct and intrusive. The TDEM is a surface geophysical technique which is non-intrusive with low spatial frequency resolution and provides averaged information about the subsurface units. In the TDEM method, electrical impulses are provided into the subsurface via large electrical coils on the surface. The recording of subsequent transient decay functions from receiver coils provides the data used in the analysis. Due to the depth involved at the WIPP site large transmitter loops (500m by 500m) were required. The primary geophysical characteristic being exploited to investigate the brines at the WIPP site is related to the fact that the brine saturated rocks are electrically more conductive than the bedded salt deposit overlying the Castile Formation. Typically the TDEM data are processed and analyzed to generate geoelectric profiles

  20. Construction of a groundwater-flow model for the Big Sioux Aquifer using airborne electromagnetic methods, Sioux Falls, South Dakota

    USGS Publications Warehouse

    Valder, Joshua F.; Delzer, Gregory C.; Carter, Janet M.; Smith, Bruce D.; Smith, David V.

    2016-09-28

    The city of Sioux Falls is the fastest growing community in South Dakota. In response to this continued growth and planning for future development, Sioux Falls requires a sustainable supply of municipal water. Planning and managing sustainable groundwater supplies requires a thorough understanding of local groundwater resources. The Big Sioux aquifer consists of glacial outwash sands and gravels and is hydraulically connected to the Big Sioux River, which provided about 90 percent of the city’s source-water production in 2015. Managing sustainable groundwater supplies also requires an understanding of groundwater availability. An effective mechanism to inform water management decisions is the development and utilization of a groundwater-flow model. A groundwater-flow model provides a quantitative framework for synthesizing field information and conceptualizing hydrogeologic processes. These groundwater-flow models can support decision making processes by mapping and characterizing the aquifer. Accordingly, the city of Sioux Falls partnered with the U.S. Geological Survey to construct a groundwater-flow model. Model inputs will include data from advanced geophysical techniques, specifically airborne electromagnetic methods.

  1. Construction of a Groundwater-Flow Model for the Big Sioux Aquifer Using Airborne Electromagnetic Methods, Sioux Falls, South Dakota

    USGS Publications Warehouse

    Valder, Joshua F.; Delzer, Gregory C.; Carter, Janet M.; Smith, Bruce D.; Smith, David V.

    2016-09-28

    The city of Sioux Falls is the fastest growing community in South Dakota. In response to this continued growth and planning for future development, Sioux Falls requires a sustainable supply of municipal water. Planning and managing sustainable groundwater supplies requires a thorough understanding of local groundwater resources. The Big Sioux aquifer consists of glacial outwash sands and gravels and is hydraulically connected to the Big Sioux River, which provided about 90 percent of the city’s source-water production in 2015. Managing sustainable groundwater supplies also requires an understanding of groundwater availability. An effective mechanism to inform water management decisions is the development and utilization of a groundwater-flow model. A groundwater-flow model provides a quantitative framework for synthesizing field information and conceptualizing hydrogeologic processes. These groundwater-flow models can support decision making processes by mapping and characterizing the aquifer. Accordingly, the city of Sioux Falls partnered with the U.S. Geological Survey to construct a groundwater-flow model. Model inputs will include data from advanced geophysical techniques, specifically airborne electromagnetic methods.

  2. Discharge measurement with salt dilution method in irrigation canals: direct sampling and geophysical controls

    NASA Astrophysics Data System (ADS)

    Comina, C.; Lasagna, M.; De Luca, D. A.; Sambuelli, L.

    2013-08-01

    An important starting point for designing management improvements, particularly in irrigation areas, is to record the baseline state of the water resources, including the amount of discharge from canals. In this respect discharge measurements by means of the salt dilution method is a traditional and well-documented technique. However, this methodology can be strongly influenced by the natural streaming characteristics of the canal (e.g. laminar vs. turbulent flow) and accurate precautions must be considered in the choice of both the measuring section and the length of the measuring reach of the canal which can affect the plume shape. The knowledge of plume distribution in the measuring cross-section is of primary importance for a correct location of sampling points aimed in obtaining a reliable measurement. To obtain this, geophysical imaging of an NaCl plume from a slug-injection salt dilution test has been performed within this paper by means of cross-flow fast electric resistivity tomography (FERT) in a real case history. Direct sampling of the same plume has been also performed with a multisampling optimization technique to obtain an average value over the measuring section by means of contemporarily sampling water in nine points. Results show that a correct visualization of the passage of the salt plume is possible by means of geophysical controls and that this can potentially help in the correct location of sampling points.

  3. Monitoring spatial and temporal variations of permeability in constructed wetlands by time-lapse geophysical methods

    NASA Astrophysics Data System (ADS)

    Tapias, J. C.; Himi, M.; Lovera, R.; Blasco, R.; Folch, M.; Casas, A.

    2012-04-01

    Constructed wetlands are widely used for removing pollutants from wastewater in small communities because their simplicity and low operation costs. Nevertheless, with time the cleaning process can result in gradual clogging of the porous layer by suspended solids, bacterial film, chemical precipitates and compactation. The clogging development causes decrease of hydraulic conductivity, reduced oxygen supply and further leads to a rapid decrease of the treatment performance. As the investment involved in reversing clogging can represent a substantial fraction of the cost of a new system it is essential to assess in advance the evolution of clogging process and detect potential failures in the system. Since there is a lack of experiences for monitoring the functionality of constructed wedlands a combination of non-destructive geophysical methods have been tested in this study. With this purpose electrical resistivity tomography, induced polarisation, frequency domain EM and ground probing radar have been conducted at different horizontal subsurface flow municipal wastewater treatment wetlands of Catalonia (Spain). The obtained results have shown that the applied geophysical techniques may delineate the clogging expansion and help take the preventive measures for enlarge the lifetime of the treatment system.

  4. Analysis of the applicability of geophysical methods and computer modelling in determining groundwater level

    NASA Astrophysics Data System (ADS)

    Czaja, Klaudia; Matula, Rafal

    2014-05-01

    The paper presents analysis of the possibilities of application geophysical methods to investigation groundwater conditions. In this paper groundwater is defined as liquid water flowing through shallow aquifers. Groundwater conditions are described through the distribution of permeable layers (like sand, gravel, fractured rock) and impermeable or low-permeable layers (like clay, till, solid rock) in the subsurface. GPR (Ground Penetrating Radar), ERT(Electrical Resistivity Tomography), VES (Vertical Electric Soundings) and seismic reflection, refraction and MASW (Multichannel Analysis of Surface Waves) belong to non - invasive, surface, geophysical methods. Due to differences in physical parameters like dielectric constant, resistivity, density and elastic properties for saturated and saturated zones it is possible to use geophysical techniques for groundwater investigations. Few programmes for GPR, ERT, VES and seismic modelling were applied in order to verify and compare results. Models differ in values of physical parameters such as dielectric constant, electrical conductivity, P and S-wave velocity and the density, layers thickness and the depth of occurrence of the groundwater level. Obtained results for computer modelling for GPR and seismic methods and interpretation of test field measurements are presented. In all of this methods vertical resolution is the most important issue in groundwater investigations. This require proper measurement methodology e.g. antennas with frequencies high enough, Wenner array in electrical surveys, proper geometry for seismic studies. Seismic velocities of unconsolidated rocks like sand and gravel are strongly influenced by porosity and water saturation. No influence of water saturation degree on seismic velocities is observed below a value of about 90% water saturation. A further saturation increase leads to a strong increase of P-wave velocity and a slight decrease of S-wave velocity. But in case of few models only the

  5. The generalized cross-validation method applied to geophysical linear traveltime tomography

    NASA Astrophysics Data System (ADS)

    Bassrei, A.; Oliveira, N. P.

    2009-12-01

    The oil industry is the major user of Applied Geophysics methods for the subsurface imaging. Among different methods, the so-called seismic (or exploration seismology) methods are the most important. Tomography was originally developed for medical imaging and was introduced in exploration seismology in the 1980's. There are two main classes of geophysical tomography: those that use only the traveltimes between sources and receivers, which is a cinematic approach and those that use the wave amplitude itself, being a dynamic approach. Tomography is a kind of inverse problem, and since inverse problems are usually ill-posed, it is necessary to use some method to reduce their deficiencies. These difficulties of the inverse procedure are associated with the fact that the involved matrix is ill-conditioned. To compensate this shortcoming, it is appropriate to use some technique of regularization. In this work we make use of regularization with derivative matrices, also called smoothing. There is a crucial problem in regularization, which is the selection of the regularization parameter lambda. We use generalized cross validation (GCV) as a tool for the selection of lambda. GCV chooses the regularization parameter associated with the best average prediction for all possible omissions of one datum, corresponding to the minimizer of GCV function. GCV is used for an application in traveltime tomography, where the objective is to obtain the 2-D velocity distribution from the measured values of the traveltimes between sources and receivers. We present results with synthetic data, using a geological model that simulates different features, like a fault and a reservoir. The results using GCV are very good, including those contaminated with noise, and also using different regularization orders, attesting the feasibility of this technique.

  6. Detection of underground voids in Ohio by use of geophysical methods

    USGS Publications Warehouse

    Munk, Jens; Sheets, R.A.

    1997-01-01

    Geophysical methods are generally classified as electrical, potential field, and seismic methods. Each method type relies on contrasts of physical properties in the subsurface. Forward models based on the physical properties of air- and water-filled voids within common geologic materials indicate that several geophysical methods are technically feasible for detection of subsurface voids in Ohio, but ease of use and interpretation varies widely between the methods. Ground-penetrating radar is the most rapid and cost-effective method for collection of subsurface data in areas associated with voids under roadways. Electrical resistivity, gravity, or seismic reflection methods have applications for direct delineation of voids, but data-collection and analytical procedures are more time consuming. Electrical resistivity, electromagnetic, or magnetic methods may be useful in locating areas where conductive material, such as rail lines, are present in abandoned underground coal mines. Other electrical methods include spontaneous potential and very low frequency (VLF); these latter two methods are considered unlikely candidates for locating underground voids in Ohio. Results of ground-penetrating radar surveys at three highway sites indicate that subsurface penetration varies widely with geologic material type and amount of cultural interference. Two highway sites were chosen over abandoned underground coal mines in eastern Ohio. A third site in western Ohio was chosen in an area known to be underlain by naturally occurring voids in lime stone. Ground-penetrating radar surveys at Interstate 470, in Belmont County, Ohio, indicate subsurface penetration of less than 15 feet over a mined coal seam that was known to vary in depth from 0 to 40 feet. Although no direct observations of voids were made, anomalous areas that may be related to collapse structures above voids were indicated. Cultural interference dominated the radar records at Interstate 70, Guernsey County, Ohio

  7. Collaborative research: Hydrogeological-geophysical methods for subsurface site characterization. 1997 annual progress report

    SciTech Connect

    Rubin, Y.; Morrison, F.; Rector, J.

    1997-10-31

    'In the first year of the project progress has been made in several areas which are central to the project. Development of Joint Hydrogcological-Geophysical Co-Interpretation Procedure A strong effort was invested in developing the concepts and the algorithm of the joint hydrogeological-geophysical co-interpretation approach. The reason for the concerted effort in that direction is the large amount of time the authors expect this task will take before completion, and also by the need to direct the data collection efforts. They are currently testing several ideas for co-interpretation, but they are at a quite advanced stage. They are testing these ideas using synthetic studies as well as some preliminary data that has been collected at the Lawrence Livermore National Lab site. Part of the efforts is in developing methods for estimation of the semi-variograms of the logconductivity based on direct measurements as well as on seimsic velocity measurements as obtained from cross-well tomography. Preliminary tests show that these two sources of data complement each other quite well: the direct measurements supply the medium to small wave number portion of the logconductivity spectra, while a high resolution seismic survey supplies a good coverage of the large wave number part of the spectra. They advanced significantly with formulating their approach for using Ground Penetrating Radar (GPR) imaging techniques in shallow subsurface surveys. Synthetic surveys show that GPR maybe very suitable for mapping spatial variations in saturations. They have access to field data and are analyzing it. Some additional issues that were investigated are also listed.'

  8. Automated counting of airborne asbestos fibers by a high-throughput microscopy (HTM) method.

    PubMed

    Cho, Myoung-Ock; Yoon, Seonghee; Han, Hwataik; Kim, Jung Kyung

    2011-01-01

    Inhalation of airborne asbestos causes serious health problems such as lung cancer and malignant mesothelioma. The phase-contrast microscopy (PCM) method has been widely used for estimating airborne asbestos concentrations because it does not require complicated processes or high-priced equipment. However, the PCM method is time-consuming and laborious as it is manually performed off-site by an expert. We have developed a high-throughput microscopy (HTM) method that can detect fibers distinguishable from other spherical particles in a sample slide by image processing both automatically and quantitatively. A set of parameters for processing and analysis of asbestos fiber images was adjusted for standard asbestos samples with known concentrations. We analyzed sample slides containing airborne asbestos fibers collected at 11 different workplaces following PCM and HTM methods, and found a reasonably good agreement in the asbestos concentration. Image acquisition synchronized with the movement of the robotic sample stages followed by an automated batch processing of a stack of sample images enabled us to count asbestos fibers with greatly reduced time and labors. HTM should be a potential alternative to conventional PCM, moving a step closer to realization of on-site monitoring of asbestos fibers in air.

  9. Integration of geophysical, ground surface, and remote sensing methods to identify ice features in discontinuous permafrost near Fairbanks, Alaska

    NASA Astrophysics Data System (ADS)

    Douglas, T. A.; Bjella, K.; Hiemstra, C. A.; Newman, S. D.; Anderson, J.; Edwards, J.; Arcone, S. A.; Wagner, A. M.; Barbato, R.; Berkowitz, J.; Deeb, E. J.

    2014-12-01

    Ground ice features such as ice wedges, segregation ice, and thermokarst cave ice are present in the subsurface in a variety of spatial scales and patterns. Accurately identifying the character and extent of these ice features in permafrost terrains allows engineers and planners to cost effectively create innovative infrastructure designs to withstand the changing environment. We are assembling a holistic view of how a variety of surficial and standoff geophysical measurements can be combined with classic ground based measurements to delineate subsurface permafrost features. We are combining horizontal geophysical measurements; borehole mapping; multispectral and radar remote sensing; airborne and ground-based LiDAR; snow, soil, and vegetation mapping; and subsurface thermal measurements and modeling at three field sites in discontinuous permafrost of Interior Alaska. Our sites cross transects representing upland and lowland permafrost and a variety of soil and vegetation compositions. With our measurements we identified and mapped a 300 meter wide swath of ice rich frozen peat at one of our lowland field sites. The high ice content was confirmed with borehole measurements. This ice rich permafrost region yields higher electrical resistivity values than the nearby permafrost and is associated with anomalously low seasonal thaw depths compared to other sites nearby. Surface soils in the ice rich region have high soil moisture contents, low redox potential (30-100 mV), and elevated soil microbial activity. The ice rice region yields low phase changes from paired interferometric synthetic aperture radar measurements collected in late spring and late summer. One interpretation of this result is that the ice rich area experiences minimal summer season subsidence. Taken in total, our results suggest the ice rich peat region has distinct surface signatures and subsurface geophysical characteristics that may be extrapolated to other areas to identify ice rich permafrost in

  10. Methods for describing airborne fractions of free fall spills of powders and liquids

    SciTech Connect

    Ballinger, M.Y.; Buck, J.W.; Owczarski, P.C.; Ayer, J.E.

    1988-01-01

    Pacific Northwest Laboratory developed calculational methods to characterize aerosols produced in hypothetical spill accidents. These methods were developed for the US Nuclear Regulatory Commission to use when evaluating the consequence of postulated accidents for safety analyses and environmental impact statements. Basic physical properties and mechanistic descriptions of spill events were used as a basis for the methods. Source term models consist of equations that can be used to estimate the mass airborne and particle size distribution of aerosols produced by spills of powders and solutions. Experimental data from Sutter et al. (1981) and Ballinger and Hodgson (1986) were emphasized in the models. Parameter ranges for this data were spill height 1 to 3 m, powder mass 25 to 1000 g, and liquid volume 125 to 1000 ml. Liquids spilled included slurries and solutions of varying viscosities. Liquid spills differed from powders in that an aerosol was produced on impact instead of during the fall. The fraction airborne from liquid spills (including viscous solutions and slurries) correlated well with three dimensionless numbers: the Archimedes number, the Froude number, and a density ratio. Liquid aerosol parameters were statistical descriptions of the log-normal distributions. A computer code was developed to model powder spills. In the code, the mass airborne was assumed proportional to the drag force on the power as it falls. The proportionality factor was empirically found to be a function of a dimensionless number, the Galileo number. 16 refs., 2 figs., 13 tabs.

  11. Basis and methods of NASA airborne topographic mapper lidar surveys for coastal studies

    USGS Publications Warehouse

    Brock, John C.; Wright, C. Wayne; Sallenger, Asbury H.; Krabill, William B.; Swift, Robert N.

    2002-01-01

    This paper provides an overview of the basic principles of airborne laser altimetry for surveys of coastal topography, and describes the methods used in the acquisition and processing of NASA Airborne Topographic Mapper (ATM) surveys that cover much of the conterminous US coastline. This form of remote sensing, also known as "topographic lidar", has undergone extremely rapid development during the last two decades, and has the potential to contribute within a wide range of coastal scientific investigations. Various airborne laser surveying (ALS) applications that are relevant to coastal studies are being pursued by researchers in a range of Earth science disciplines. Examples include the mapping of "bald earth" land surfaces below even moderately dense vegetation in studies of geologic framework and hydrology, and determination of the vegetation canopy structure, a key variable in mapping wildlife habitats. ALS has also proven to be an excellent method for the regional mapping of geomorphic change along barrier island beaches and other sandy coasts due to storms or long-term sedimentary processes. Coastal scientists are adopting ALS as a basic method in the study of an array of additional coastal topics. ALS can provide useful information in the analysis of shoreline change, the prediction and assessment of landslides along seacliffs and headlands, examination of subsidence causing coastal land loss, and in predicting storm surge and tsunami inundation.

  12. Cross validation of geotechnical and geophysical site characterization methods: near surface data from selected accelerometric stations in Crete (Greece)

    NASA Astrophysics Data System (ADS)

    Loupasakis, C.; Tsangaratos, P.; Rozos, D.; Rondoyianni, Th.; Vafidis, A.; Kritikakis, G.; Steiakakis, M.; Agioutantis, Z.; Savvaidis, A.; Soupios, P.; Papadopoulos, I.; Papadopoulos, N.; Sarris, A.; Mangriotis, M.-D.; Dikmen, U.

    2015-06-01

    The specification of the near surface ground conditions is highly important for the design of civil constructions. These conditions determine primarily the ability of the foundation formations to bear loads, the stress - strain relations and the corresponding settlements, as well as the soil amplification and corresponding peak ground motion in case of dynamic loading. The static and dynamic geotechnical parameters as well as the ground-type/soil-category can be determined by combining geotechnical and geophysical methods, such as engineering geological surface mapping, geotechnical drilling, in situ and laboratory testing and geophysical investigations. The above mentioned methods were combined, through the Thalis ″Geo-Characterization″ project, for the site characterization in selected sites of the Hellenic Accelerometric Network (HAN) in the area of Crete Island. The combination of the geotechnical and geophysical methods in thirteen (13) sites provided sufficient information about their limitations, setting up the minimum tests requirements in relation to the type of the geological formations. The reduced accuracy of the surface mapping in urban sites, the uncertainties introduced by the geophysical survey in sites with complex geology and the 1D data provided by the geotechnical drills are some of the causes affecting the right order and the quantity of the necessary investigation methods. Through this study the gradual improvement on the accuracy of site characterization data is going to be presented by providing characteristic examples from a total number of thirteen sites. Selected examples present sufficiently the ability, the limitations and the right order of the investigation methods.

  13. Testing different classification methods in airborne hyperspectral imagery processing.

    PubMed

    Kozoderov, Vladimir V; Dmitriev, Egor V

    2016-05-16

    To enhance the efficiency of machine-learning algorithms of optical remote sensing imagery processing, optimization techniques are evolved of the land surface objects pattern recognition. Different methods of supervised classification are considered for these purposes, including the metrical classifier operating with Euclidean distance between any points of the multi-dimensional feature space given by registered spectra, the K-nearest neighbors classifier based on a majority vote for neighboring pixels of the recognized objects, the Bayesian classifier of statistical decision making, the Support Vector Machine classifier dealing with stable solutions of the mini-max optimization problem and their different modifications. We describe the related techniques applied for selected test regions to compare the listed classifiers. PMID:27409968

  14. Combined geophysical methods for mapping infiltration pathways at the Aurora Water Aquifer recharge and recovery site

    NASA Astrophysics Data System (ADS)

    Jasper, Cameron A.

    Although aquifer recharge and recovery systems are a sustainable, decentralized, low cost, and low energy approach for the reclamation, treatment, and storage of post- treatment wastewater, they can suffer from poor infiltration rates and the development of a near-surface clogging layer within infiltration ponds. One such aquifer recharge and recovery system, the Aurora Water site in Colorado, U.S.A, functions at about 25% of its predicted capacity to recharge floodplain deposits by flooding infiltration ponds with post-treatment wastewater extracted from river bank aquifers along the South Platte River. The underwater self-potential method was developed to survey self-potential signals at the ground surface in a flooded infiltration pond for mapping infiltration pathways. A method for using heat as a groundwater tracer within the infiltration pond used an array of in situ high-resolution temperature sensing probes. Both relatively positive and negative underwater self-potential anomalies are consistent with observed recovery well pumping rates and specific discharge estimates from temperature data. Results from electrical resistivity tomography and electromagnetics surveys provide consistent electrical conductivity distributions associated with sediment textures. A lab method was developed for resistivity tests of near-surface sediment samples. Forward numerical modeling synthesizes the geophysical information to best match observed self- potential anomalies and provide permeability distributions, which is important for effective aquifer recharge and recovery system design, and optimization strategy development.

  15. An efficient analytical method for particle counting in evaluating airborne infectious isolation containment using fluorescent microspheres.

    PubMed

    Johnson, David L; Lynch, Robert A

    2008-04-01

    The containment performance of patient isolation enclosures, particularly expedient surge capacity enclosures, must be verified to protect health care providers and staff, other patients, and hospital visitors. Tracer gas methods are often used, but requirements for special equipment and training limit the technique's utility. A technologically simple yet accurate and precise particle-based technique is needed to measure the low count concentrations of escaping airborne particles that might be present outside an isolation enclosure. Reported here is the performance of such a technique employing micrometer-sized fluorescent polystyrene latex microspheres as a surrogate for pathogenic bioaerosols. Particles are released into the isolation enclosure, air is sampled inside and outside the room to capture airborne particles on 25 mm diameter filters, and the number of particles deposited on a filter is quantified using an optimized random field counting approach. The technique accurately estimates the number of surrogate bioaerosol particles on the filter, allowing calculation of the airborne particle concentrations inside and outside the enclosure, and the containment efficiency. This technique can be employed using generally available equipment and inexpensive supplies and also can minimize the number of particle counts that must be performed. The method is shown to be specific, sensitive, and accurate.

  16. An efficient analytical method for particle counting in evaluating airborne infectious isolation containment using fluorescent microspheres.

    PubMed

    Johnson, David L; Lynch, Robert A

    2008-04-01

    The containment performance of patient isolation enclosures, particularly expedient surge capacity enclosures, must be verified to protect health care providers and staff, other patients, and hospital visitors. Tracer gas methods are often used, but requirements for special equipment and training limit the technique's utility. A technologically simple yet accurate and precise particle-based technique is needed to measure the low count concentrations of escaping airborne particles that might be present outside an isolation enclosure. Reported here is the performance of such a technique employing micrometer-sized fluorescent polystyrene latex microspheres as a surrogate for pathogenic bioaerosols. Particles are released into the isolation enclosure, air is sampled inside and outside the room to capture airborne particles on 25 mm diameter filters, and the number of particles deposited on a filter is quantified using an optimized random field counting approach. The technique accurately estimates the number of surrogate bioaerosol particles on the filter, allowing calculation of the airborne particle concentrations inside and outside the enclosure, and the containment efficiency. This technique can be employed using generally available equipment and inexpensive supplies and also can minimize the number of particle counts that must be performed. The method is shown to be specific, sensitive, and accurate. PMID:18286424

  17. Fast 3D inversion of airborne gravity-gradiometry data using Lanczos bidiagonalization method

    NASA Astrophysics Data System (ADS)

    Meng, Zhaohai; Li, Fengting; Zhang, Dailei; Xu, Xuechun; Huang, Danian

    2016-09-01

    We developed a new fast inversion method for to process and interpret airborne gravity gradiometry data, which was based on Lanczos bidiagonalization algorithm. Here, we describe the application of this new 3D gravity gradiometry inversion method to recover a subsurface density distribution model from the airborne measured gravity gradiometry anomalies. For this purpose, the survey area is divided into a large number of rectangular cells with each cell possessing a constant unknown density. It is well known that the solution of large linear gravity gradiometry is an ill-posed problem since using the smoothest inversion method is considerably time consuming. We demonstrate that the Lanczos bidiagonalization method can be an appropriate algorithm to solve a Tikhonov solver time cost function for resolving the large equations within a short time. Lanczos bidiagonalization is designed to make the very large gravity gradiometry forward modeling matrices to become low-rank, which will considerably reduce the running time of the inversion method. We also use a weighted generalized cross validation method to choose the appropriate Tikhonov parameter to improve inversion results. The inversion incorporates a model norm that allows us to attain the smoothing and depth of the solution; in addition, the model norm counteracts the natural decay of the kernels, which concentrate at shallow depths. The method is applied on noise-contaminated synthetic gravity gradiometry data to demonstrate its suitability for large 3D gravity gradiometry data inversion. The airborne gravity gradiometry data from the Vinton Salt Dome, USE, were considered as a case study. The validity of the new method on real data is discussed with reference to the Vinton Dome inversion result. The intermediate density values in the constructed model coincide well with previous results and geological information. This demonstrates the validity of the gravity gradiometry inversion method.

  18. Performance of Three Reflectance Calibration Methods for Airborne Hyperspectral Spectrometer Data

    PubMed Central

    Miura, Tomoaki; Huete, Alfredo R.

    2009-01-01

    In this study, the performances and accuracies of three methods for converting airborne hyperspectral spectrometer data to reflectance factors were characterized and compared. The “reflectance mode (RM)” method, which calibrates a spectrometer against a white reference panel prior to mounting on an aircraft, resulted in spectral reflectance retrievals that were biased and distorted. The magnitudes of these bias errors and distortions varied significantly, depending on time of day and length of the flight campaign. The “linear-interpolation (LI)” method, which converts airborne spectrometer data by taking a ratio of linearly-interpolated reference values from the preflight and post-flight reference panel readings, resulted in precise, but inaccurate reflectance retrievals. These reflectance spectra were not distorted, but were subject to bias errors of varying magnitudes dependent on the flight duration length. The “continuous panel (CP)” method uses a multi-band radiometer to obtain continuous measurements over a reference panel throughout the flight campaign, in order to adjust the magnitudes of the linear-interpolated reference values from the preflight and post-flight reference panel readings. Airborne hyperspectral reflectance retrievals obtained using this method were found to be the most accurate and reliable reflectance calibration method. The performances of the CP method in retrieving accurate reflectance factors were consistent throughout time of day and for various flight durations. Based on the dataset analyzed in this study, the uncertainty of the CP method has been estimated to be 0.0025 ± 0.0005 reflectance units for the wavelength regions not affected by atmospheric absorptions. The RM method can produce reasonable results only for a very short-term flight (e.g., < 15 minutes) conducted around a local solar noon. The flight duration should be kept shorter than 30 minutes for the LI method to produce results with reasonable accuracies

  19. Performance of three reflectance calibration methods for airborne hyperspectral spectrometer data.

    PubMed

    Miura, Tomoaki; Huete, Alfredo R

    2009-01-01

    In this study, the performances and accuracies of three methods for converting airborne hyperspectral spectrometer data to reflectance factors were characterized and compared. The "reflectance mode (RM)" method, which calibrates a spectrometer against a white reference panel prior to mounting on an aircraft, resulted in spectral reflectance retrievals that were biased and distorted. The magnitudes of these bias errors and distortions varied significantly, depending on time of day and length of the flight campaign. The "linear-interpolation (LI)" method, which converts airborne spectrometer data by taking a ratio of linearly-interpolated reference values from the preflight and post-flight reference panel readings, resulted in precise, but inaccurate reflectance retrievals. These reflectance spectra were not distorted, but were subject to bias errors of varying magnitudes dependent on the flight duration length. The "continuous panel (CP)" method uses a multi-band radiometer to obtain continuous measurements over a reference panel throughout the flight campaign, in order to adjust the magnitudes of the linear-interpolated reference values from the preflight and post-flight reference panel readings. Airborne hyperspectral reflectance retrievals obtained using this method were found to be the most accurate and reliable reflectance calibration method. The performances of the CP method in retrieving accurate reflectance factors were consistent throughout time of day and for various flight durations. Based on the dataset analyzed in this study, the uncertainty of the CP method has been estimated to be 0.0025 ± 0.0005 reflectance units for the wavelength regions not affected by atmospheric absorptions. The RM method can produce reasonable results only for a very short-term flight (e.g., < 15 minutes) conducted around a local solar noon. The flight duration should be kept shorter than 30 minutes for the LI method to produce results with reasonable accuracies. An important

  20. A comparison of two sampling methods for the detection of airborne methylene bisphenyl diisocyanate.

    PubMed

    Schaeffer, Joshua W; Sargent, Layne Marie; Sandfort, Delvin R; Brazile, William J

    2013-01-01

    The purpose of this study was to determine if there was a significant difference between two readily available sampling methodologies for airborne methylene bisphenyl diisocyanate (MDI), which is an essential precursor in the spray-on truck bed lining industry. Seventy-two personal airborne samples of MDI were collected and analyzed from nine spray-on truck bed liner businesses in northern Colorado. Wide ranges of exposure concentrations were encountered during the spray-on application, including concentrations that exceeded the OSHA permissible exposure limit. The highest airborne MDI concentration measured was 690 ppb. A statistically significant difference between field-desorbed and laboratory-desorbed methods was determined. The field-desorbed sampling methodology yielded consistently higher MDI concentrations than the laboratory-desorbed sampling methodology, which suggests that immediate desorption minimizes isocyanate loss and potential underestimations. Results from the analysis of variance also indicated that different facility factors and environmental conditions within each company, such as the use of ventilation or humidity level, affected the MDI concentrations, indicating the potential for better mitigation of exposures using the hierarchy of controls.

  1. Detection of Hazardous Cavities Below a Road Using Combined Geophysical Methods

    NASA Astrophysics Data System (ADS)

    De Giorgi, L.; Leucci, G.

    2014-07-01

    Assessment of the risk arising from near-surface natural hazard is a crucial step in safeguarding the security of the roads in karst areas. It helps authorities and other related parties to apply suitable procedures for ground treatment, mitigate potential natural hazards and minimize human and economic losses. Karstic terrains in the Salento Peninsula (Apulia region—South Italy) is a major challenge to engineering constructions and roads due to extensive occurrence of cavities and/or sinkholes that cause ground subsidence and both roads and building collapse. Cavities are air/sediment-filled underground voids, commonly developed in calcarenite sedimentary rocks by the infiltration of rainwater into the ground, opening up, over a long period of time, holes and tunnels. Mitigation of natural hazards can best be achieved through careful geoscientific studies. Traditionally, engineers use destructive probing techniques for the detection of cavities across regular grids or random distances. Such probing is insufficient on its own to provide confidence that cavities will not be encountered. Frequency of probing and depth of investigation may become more expensive. Besides, probing is intrusive, non-continuous, slow, expensive and cannot provide a complete lateral picture of the subsurface geology. Near-surface cavities usually can be easily detected by surface geophysical methods. Traditional and recently developed measuring techniques in seismic, geoelectrics and georadar are suitable for economical investigation of hazardous, potentially collapsing cavities. The presented research focused on an integrated geophysical survey that was carried out in a near-coast road located at Porto Cesareo, a small village a few kilometers south west of Lecce (south Italy). The roads in this area are intensively affected by dangerous surface cracks that cause structural instability. The survey aimed to image the shallow subsurface structures, including karstic features, and evaluate

  2. Use of surface-geophysical methods to assess riverbed scour at bridge piers

    USGS Publications Warehouse

    Gorin, S.R.; Haeni, F.P.

    1989-01-01

    A ground-penetrating-radar system, and three seismic systems--color fathometer, tuned transducer, and black-and-white fathometer--were used to evaluate river-bed scour at the Charter Oak, Founder 's and Bulkeley Bridges in Hartford, Connecticut. Cross-sections of the channel and some lateral sections were run at each bridge in June and July 1987, and significant scour at piers supporting each of these bridges was recorded. Each of the four geophysical systems proved to have advantages and limitations. The ground penetrating radar system used single and dual 80 megahertz antennae floating in the water to transmit and receive the signal. The method was successful in water less than 25 ft deep, and in resistive earth materials. The geometry of existing scour holes and the extent of post-scour sedimentation were clearly defined. The color fathometer, operating at a signal frequency of 20 kilohertz, delineated existing scour-hole geometry, detected infilling of scour holes, and provided qualitative information about the physical properties of sediments. The tuned transducer, operating at a signal frequency of 14 kilohertz, defined scour-hole geometry and the extent of post-scour sediment deposition. Both of these systems were effective in water greater than 5 ft deep. At a signal frequency of 200 kilohertz, the black-and-white fathometer could not penetrate post-scour deposits, but it was useful in defining existing scour-holed geometry in water of any depth. (USGS)

  3. Assessing the temporal stability of spatial patterns of soil apparent electrical conductivity using geophysical methods

    NASA Astrophysics Data System (ADS)

    De Caires, Sunshine A.; Wuddivira, Mark N.; Bekele, Isaac

    2014-10-01

    Cocoa remains in the same field for decades, resulting in plantations dominated with aging trees growing on variable and depleted soils. We determined the spatio-temporal variability of key soil properties in a (5.81 ha) field from the International Cocoa Genebank, Trinidad using geophysical methods. Multi-year (2008-2009) measurements of apparent electrical conductivity at 0-0.75 m (shallow) and 0.75-1.5 m (deep) were conducted. Apparent electrical conductivity at deep and shallow gave the strongest linear correlation with clay-silt content (R = 0.67 and R = 0.78, respectively) and soil solution electrical conductivity (R = 0.76 and R = 0.60, respectively). Spearman rank correlation coefficients ranged between 0.89-0.97 and 0.81- 0.95 for apparent electrical conductivity at deep and shallow, respectively, signifying a strong linear dependence between measurement days. Thus, in the humid tropics, cocoa fields with thick organic litter layer and relatively dense understory cover, experience minimal fluctuations in transient properties of soil water and temperature at the topsoil resulting in similarly stable apparent electrical conductivity at shallow and deep. Therefore, apparent electrical conductivity at shallow, which covers the depth where cocoa feeder roots concentrate, can be used as a fertility indicator and to develop soil zones for efficient application of inputs and management of cocoa fields.

  4. Improved method for estimating tree crown diameter using high-resolution airborne data

    NASA Astrophysics Data System (ADS)

    Brovkina, Olga; Latypov, Iscander Sh.; Cienciala, Emil; Fabianek, Tomas

    2016-04-01

    Automatic mapping of tree crown size (radius, diameter, or width) from remote sensing can provide a major benefit for practical and scientific purposes, but requires the development of accurate methods. This study presents an improved method for average tree crown diameter estimation at a forest plot level from high-resolution airborne data. The improved method consists of the combination of a window binarization procedure and a granulometric algorithm, and avoids the complicated crown delineation procedure that is currently used to estimate crown size. The systematic error in average crown diameter estimates is corrected with the improved method. The improved method is tested with coniferous, beech, and mixed-species forest plots based on airborne images of various spatial resolutions. The absolute (quantitative) accuracy of the improved crown diameter estimates is comparable or higher for both monospecies plots and mixed-species plots than the current methods. The ability of the improved method to produce good estimates for average crown diameters for monoculture and mixed species, to use remote sensing data of various spatial resolution and to operate in automatic mode promisingly suggests its applicability to a wide range of forest systems.

  5. Non-destructive tree root detection with geophysical methods in urban soils

    NASA Astrophysics Data System (ADS)

    Vianden, Mitja Johannes; Weihs, Ulrich; Kuhnke, Falko; Rust, Steffen

    2010-05-01

    To assess the safety of roadside trees or as part of ecophysiological research it is often important to investigate the spatial distribution and development of tree roots. Conventionally this is done by laborious excavations or by the application of root drills which in many cases do not allow a comprehensive data collection. An indirect method for the investigation of subsurface features is ground penetrating radar (GPR). Its ability to detect tree roots has been shown by several studies (for example Hruska et al. 1999; Butnor et al. 2001; Barton et al. 2004). Another geophysical method which has been successful applied to study different aspects of tree roots is electrical resistivity tomography (ERT) (for example Hagrey 2007; Amato et al. 2008). These former studies by other authors mainly concentrated on a correlation between the measured parameters (signal amplitude and resistivity) and root-biomass on forest sites or controlled conditions. Results of Cermak et al. (2000), studying tree roots in urban areas with GPR, indicated that this method may also be useful for anthropogenic influenced areas. As a continuation of these approaches the authors have been using both techniques to study the spatial root architecture of urban trees. This research is designed to elicit the possibilities and limitations of the methods in urban areas. Reference sites have been established to quantify the methods' resolution and assess possible fields of application. These test site measurements are the basis for the interpretation of results at urban tree sites. Their results highlight the importance of 3D-measurements in urban areas because in inhomogeneous soil other reflectors (like rocks, cables, pipes, etc.) cause similar signals and bear a risk of misinterpretation. This can be minimized if detected objects have a spatial continuation and are connected to a tree. Here we present preliminary results from a combined application of both methods at the river bank of the

  6. An Integration of Geophysical Methods to Explore Buried Structures on the Bench and in the Field

    NASA Astrophysics Data System (ADS)

    Booterbaugh, A. P.; Lachhab, A.

    2011-12-01

    In the following study, an integration of geophysical methods and devices were implemented on the bench and in the field to accurately identify buried structures. Electrical resistivity and ground penetrating radar methods, including both a fabricated electrical resistivity apparatus and an electrical resistivity device were all used in this study. The primary goal of the study was to test the accuracy and reliability of the apparatus which costs a fraction of the price of a commercially sold resistivity instrument. The apparatus consists of four electrodes, two multimeters, a 12-volt battery, a DC to AC inverter and wires. Using this apparatus, an electrical current, is injected into earth material through the outer electrodes and the potential voltage is measured across the inner electrodes using a multimeter. The recorded potential and the intensity of the current can then be used to calculate the apparent resistivity of a given material. In this study the Wenner array, which consists of four equally spaced electrodes, was used due to its higher accuracy and greater resolution when investigating lateral variations of resistivity in shallow depths. In addition, the apparatus was used with an electrical resistivity device and a ground penetrating radar unit to explore the buried building foundation of Gustavus Adolphus Hall located on Susquehanna University Campus, Selinsgrove, PA. The apparatus successfully produced consistent results on the bench level revealing the location of small bricks buried under a soil material. In the summer of 2010, seventeen electrical resistivity transects were conducted on the Gustavus Adolphus site where and revealed remnants of the foundation. In the summer of 2011, a ground penetrating radar survey and an electrical resistivity tomography survey were conducted to further explore the site. Together these methods identified the location of the foundation and proved that the apparatus was a reliable tool for regular use on the bench

  7. Evaluation of structural and geological factors in orogenic gold type mineralisation in the Kervian area, north-west Iran, using airborne geophysical data

    NASA Astrophysics Data System (ADS)

    Almasi, Alireza; Jafarirad, Alireza; Kheyrollahi, Hasan; Rahimi, Mana; Afzal, Peyman

    2014-03-01

    The Piranshahr-Sardasht-Saqqez Zone (PSSZ) in the north-west of the Sanandaj-Sirjan metamorphic zone (SSZ) hosts some major Iranian gold deposits. In the south-east of PSSZ, there is a north-east trending orogenic gold belt which contains three gold deposits/occurrences (Qolqoleh, Kervian and Ghabaghloujeh). In this research, studies are focused on processing and analysing airborne magnetic and radiometric data in order to find applicable indicators for prospecting gold in this area. Former studies on the gold deposits/occurrences in the study area suggest three essential factors in local orogenic gold mineralisation: (1) intersecting deep bending structures/shear zones, (2) Fe-rich mafic meta-volcanic lithologies (primary source and host rocks) and (3) altered mylonitic granites (secondary host rock). Geological structures and lithological contacts can be mapped based on locating edges in the magnetic field at different depths. In this study, we extracted the structure from aeromagnetic data by reduction to the pole, upward continuation and applying a tilt derivative filter to the horizontal derivative of the upward continued data. Upward continuation was to several levels from 500 to 4000 m. Afterwards, a 3D architecture was built based on extracted subsurface lineaments in different levels. This 3D model can assist in the visualisation of the underground shape of structures that may influence gold mineralisation. Moreover, mafic meta-volcanic rocks in the study area, which contain magnetic minerals such as magnetite, titanomagnetite and ilmenite, can be mapped using aeromagnetic data. Mylonitic granites, which are the other host rock in the deposits, were mapped using airborne radiometric data.

  8. Automated extraction of absorption features from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and Geophysical and Environmental Research Imaging Spectrometer (GERIS) data

    NASA Technical Reports Server (NTRS)

    Kruse, Fred A.; Calvin, Wendy M.; Seznec, Olivier

    1988-01-01

    Automated techniques were developed for the extraction and characterization of absorption features from reflectance spectra. The absorption feature extraction algorithms were successfully tested on laboratory, field, and aircraft imaging spectrometer data. A suite of laboratory spectra of the most common minerals was analyzed and absorption band characteristics tabulated. A prototype expert system was designed, implemented, and successfully tested to allow identification of minerals based on the extracted absorption band characteristics. AVIRIS spectra for a site in the northern Grapevine Mountains, Nevada, have been characterized and the minerals sericite (fine grained muscovite) and dolomite were identified. The minerals kaolinite, alunite, and buddingtonite were identified and mapped for a site at Cuprite, Nevada, using the feature extraction algorithms on the new Geophysical and Environmental Research 64 channel imaging spectrometer (GERIS) data. The feature extraction routines (written in FORTRAN and C) were interfaced to the expert system (written in PROLOG) to allow both efficient processing of numerical data and logical spectrum analysis.

  9. IGY to IPY, the U.S. Antarctic oversnow and airborne geophysical-glaciological research program from 1957 to 1964 from the view of a young graduate student

    USGS Publications Warehouse

    Behrendt, John C.

    2007-01-01

    When 12 countries established scientific stations in Antarctica for the 1957-58 (IGY), the Cold War was at its height, seven countries had made claims in Antarctica, and the Antarctic Treaty was in the future. The only major field project of the U.S. IGY Antarctic program was series of oversnow traverses, starting in 1957, making seismic reflection ice soundings (and other geophysical measurements) and glaciological studies. The U.S.S.R. and France made similar traverses coordinated through the IGY. Although geology and topographic mapping were not part of the IGY program because of the claims issue and the possibility of mineral resources, the oversnow traverse parties did geologic work, during which unknown mountains were discovered. The oversnow traverses continued through 1966 and resulted in an excellent first approximation of the snow surface elevation, ice thickness and bed topography of Antarctica, as well as the mean annual temperature of that era and snow accumulation.

  10. Applications of the POCS inversion method to interpolating topography and other geophysical fields. [Projection Onto Convex Sets

    SciTech Connect

    Menke, W. )

    1991-03-01

    The author applies the method of Projection Onto Convex Sets (POCS) to the problem of solving geophysical inverse problems. The advantage of this iterative method is its flexibility in handling non-linear equality and inequality constraints, including constraints on the spectrum of unknown functions. He gives examples of using POCS to interpolate topographic profiles, topographic maps, and the physical properties of the earth between well logs.

  11. Combined geophysical methods for detecting soil thickness distribution on a weathered granitic hillslope

    NASA Astrophysics Data System (ADS)

    Yamakawa, Yosuke; Kosugi, Ken'ichirou; Masaoka, Naoya; Sumida, Jun; Tani, Makoto; Mizuyama, Takahisa

    2012-04-01

    The usefulness of electrical resistivity imaging (ERI) as a highly accurate method for determining the soil thickness distribution on hillslopes was validated by combining intensive measurements using invasive methods, i.e., cone penetration testing and boreholes, with ERI in three granitic watersheds. Areas of high electrical resistivity (ρ) contrast reflecting soil-bedrock interfaces were found in all three study watersheds. However, ρ values of soil and weathered granite just below the soil mantle varied over a relatively wide range at each site, as well as considerably from site to site. The patterns of low-high contrast in ρ profiles, reflecting the soil-bedrock interface, also differed from site to site despite similarly dry conditions. Differences in the water retention characteristics of soil and weathered granitic bedrock, as found by a previous study of bedrock hydrological properties, may have been a major factor in the observed subsurface ρ variations. The ERI method, with electrode spacing of 0.5 to 2.0 m, was successful in determining soil thickness distributions ranging from about 0.5 to 3 m depth based on its ability to detect high contrast in ρ in the subsurface zone. Closer electrode spacings are expected to more sensitively reveal the distribution of ground material properties and thus more accurately replicate the soil-bedrock interface. ERI failed to clearly identify the soil-bedrock interface at some points along our measurement lines because of local intermediate materials with different properties such as unconsolidated soil and clayey intermediation just below the soil-bedrock interface. Two types of seismic survey (SS) techniques were also used, combining seismic refraction (SR) and the surface wave method (SWM) with the ERI method in a granitic watershed to compare ERI with other geophysical methods. The profile of S-wave velocity (Vs) by SWM also reasonably duplicated the soil-bedrock interface; the Vs profile showed larger

  12. New Geophysical Technique for Mineral Exploration and Mineral Discrimination Based on Electromagnetic Methods

    SciTech Connect

    Michael S. Zhdanov

    2009-03-09

    The research during the first two years of the project was focused on developing the foundations of a new geophysical technique for mineral exploration and mineral discrimination, based on electromagnetic (EM) methods. The developed new technique is based on examining the spectral induced polarization effects in electromagnetic data using effective-medium theory and advanced methods of 3-D modeling and inversion. The analysis of IP phenomena is usually based on models with frequency dependent complex conductivity distribution. In this project, we have developed a rigorous physical/mathematical model of heterogeneous conductive media based on the effective-medium approach. The new generalized effective-medium theory of IP effect (GEMTIP) provides a unified mathematical method to study heterogeneity, multi-phase structure, and polarizability of rocks. The geoelectrical parameters of a new composite conductivity model are determined by the intrinsic petrophysical and geometrical characteristics of composite media: mineralization and/or fluid content of rocks, matrix composition, porosity, anisotropy, and polarizability of formations. The new GEMTIP model of multi-phase conductive media provides a quantitative tool for evaluation of the type of mineralization, and the volume content of different minerals using electromagnetic data. We have developed a 3-D EM-IP modeling algorithm using the integral equation (IE) method. Our IE forward modeling software is based on the contraction IE method, which improves the convergence rate of the iterative solvers. This code can handle various types of sources and receivers to compute the effect of a complex resistivity model. We have demonstrated that the generalized effective-medium theory of induced polarization (GEMTIP) in combination with the IE forward modeling method can be used for rock-scale forward modeling from grain-scale parameters. The numerical modeling study clearly demonstrates how the various complex resistivity

  13. "Geo-statistics methods and neural networks in geophysical applications: A case study"

    NASA Astrophysics Data System (ADS)

    Rodriguez Sandoval, R.; Urrutia Fucugauchi, J.; Ramirez Cruz, L. C.

    2008-12-01

    The study is focus in the Ebano-Panuco basin of northeastern Mexico, which is being explored for hydrocarbon reservoirs. These reservoirs are in limestones and there is interest in determining porosity and permeability in the carbonate sequences. The porosity maps presented in this study are estimated from application of multiattribute and neural networks techniques, which combine geophysics logs and 3-D seismic data by means of statistical relationships. The multiattribute analysis is a process to predict a volume of any underground petrophysical measurement from well-log and seismic data. The data consist of a series of target logs from wells which tie a 3-D seismic volume. The target logs are neutron porosity logs. From the 3-D seismic volume a series of sample attributes is calculated. The objective of this study is to derive a set of attributes and the target log values. The selected set is determined by a process of forward stepwise regression. The analysis can be linear or nonlinear. In the linear mode the method consists of a series of weights derived by least-square minimization. In the nonlinear mode, a neural network is trained using the select attributes as inputs. In this case we used a probabilistic neural network PNN. The method is applied to a real data set from PEMEX. For better reservoir characterization the porosity distribution was estimated using both techniques. The case shown a continues improvement in the prediction of the porosity from the multiattribute to the neural network analysis. The improvement is in the training and the validation, which are important indicators of the reliability of the results. The neural network showed an improvement in resolution over the multiattribute analysis. The final maps provide more realistic results of the porosity distribution.

  14. A method for detecting and locating geophysical events using groups of arrays

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, Catherine D.; Hedlin, Michael A. H.

    2015-11-01

    We have developed a novel method to detect and locate geophysical events that makes use of any sufficiently dense sensor network. This method is demonstrated using acoustic sensor data collected in 2013 at the USArray Transportable Array (TA). The algorithm applies Delaunay triangulation to divide the sensor network into a mesh of three-element arrays, called triads. Because infrasound waveforms are incoherent between the sensors within each triad, the data are transformed into envelopes, which are cross-correlated to find signals that satisfy a consistency criterion. The propagation azimuth, phase velocity and signal arrival time are computed for each signal. Triads with signals that are consistent with a single source are bundled as an event group. The ensemble of arrival times and azimuths of detected signals within each group are used to locate a common source in space and time. A total of 513 infrasonic stations that were active for part or all of 2013 were divided into over 2000 triads. Low (0.5-2 Hz) and high (2-8 Hz) catalogues of infrasonic events were created for the eastern USA. The low-frequency catalogue includes over 900 events and reveals several highly active source areas on land that correspond with coal mining regions. The high-frequency catalogue includes over 2000 events, with most occurring offshore. Although their cause is not certain, most events are clearly anthropogenic as almost all occur during regular working hours each week. The regions to which the TA is most sensitive vary seasonally, with the direction of reception dependent on the direction of zonal winds. The catalogue has also revealed large acoustic events that may provide useful insight into the nature of long-range infrasound propagation in the atmosphere.

  15. The U.S. Antarctic Oversnow and Airborne Geophysical-Glaciological Research Program of the International Geophysical Year (IGY) 1957-58 Period from the View of a Research Scientist Participant

    NASA Astrophysics Data System (ADS)

    Behrendt, J. C.

    2005-12-01

    When 12 countries established scientific stations in Antarctica for the 1957-58 International Geophysical Year (IGY), the Cold War was at its height, seven countries had made claims in Antarctica, and the Antarctic Treaty was a few years in the future. The U.S. program was operated by the Navy and territorial claims were secretly made at several locations during the IGY; these were never officially announced and the U.S. remains a non-claimant state. I was a graduate student geophysicist (assistant seismologist) on the unexplored Filchner-Ronne Ice Shelf as part of the only large scale field project of the U.S. program. Starting in 1956, the U.S. began a series of oversnow traverses making seismic reflection ice soundings (and other geophysical measurements) and glaciological studies to determine the thickness and budget of the Antarctic Ice Sheet. The USSR and France made similar traverses coordinated through the IGY. Although geology and topographic mapping were not part of the IGY program because of the claims issue, and the possibility of mineral resources discoveries, the oversnow traverse parties did geologic work where unknown mountains were discovered. The oversnow traverses continued through 1966, and resulted in an excellent first approximation of the snow surface elevation, ice thickness and bed topography of Antarctica, as well as mean annual temperature of that era and snow accumulation. The vacuum tube dictated the logistics of the oversnow traverse program. Seismic equipment including heavy batteries weighed about 500 kg. Therefore a Sno-Cat tracked vehicle was needed to carry this load. Usually three such vehicles were needed for safety. Because about 3-4 l/km of Sno-Cat fuel was consumed, as much as 120 kg/day of fuel was required. A resupply flight could only carry only about 600 kg/flight (varying greatly as to range and type of aircraft), the major air logistic program of the U.S. IGY program were the three oversnow traverses (other than the

  16. New Geophysical Technique for Mineral Exploration and Mineral Discrimination Based on Electromagnetic Methods

    SciTech Connect

    Michael S. Zhdanov

    2005-03-09

    The research during the first year of the project was focused on developing the foundations of a new geophysical technique for mineral exploration and mineral discrimination, based on electromagnetic (EM) methods. The proposed new technique is based on examining the spectral induced polarization effects in electromagnetic data using modern distributed acquisition systems and advanced methods of 3-D inversion. The analysis of IP phenomena is usually based on models with frequency dependent complex conductivity distribution. One of the most popular is the Cole-Cole relaxation model. In this progress report we have constructed and analyzed a different physical and mathematical model of the IP effect based on the effective-medium theory. We have developed a rigorous mathematical model of multi-phase conductive media, which can provide a quantitative tool for evaluation of the type of mineralization, using the conductivity relaxation model parameters. The parameters of the new conductivity relaxation model can be used for discrimination of the different types of rock formations, which is an important goal in mineral exploration. The solution of this problem requires development of an effective numerical method for EM forward modeling in 3-D inhomogeneous media. During the first year of the project we have developed a prototype 3-D IP modeling algorithm using the integral equation (IP) method. Our IE forward modeling code INTEM3DIP is based on the contraction IE method, which improves the convergence rate of the iterative solvers. This code can handle various types of sources and receivers to compute the effect of a complex resistivity model. We have tested the working version of the INTEM3DIP code for computer simulation of the IP data for several models including a southwest US porphyry model and a Kambalda-style nickel sulfide deposit. The numerical modeling study clearly demonstrates how the various complex resistivity models manifest differently in the observed EM

  17. Mapping Groundwater in an Alpine Drainage with Airborne Electromagnetic Methods and Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Hein, A.; Armstrong, R. S.; Holbrook, W. S.; Parsekian, A.

    2015-12-01

    The rivers that supply water to most of the West rise in the Rocky Mountains. As drought increases across the country, understanding the hydrology of these alpine regions becomes important to assuring water supplies in the future. Near surface geophysics can help in this effort. In this study, resistivity data from an airborne electromagnetic survey in the Snowy Range was analyzed to map groundwater distribution. The EM survey covered an area of approximately 60 km2 to a depth of around 150 m. Nuclear magnetic resonance (NMR) point soundings provided ground truthing by testing whether water was present, at what depth, and how much. The survey area contained vertically dipping metasedimentary rocks, covered in places by unconsolidated glacial and fluvial deposits. The resistivity data showed horizontal variation in water content much more clearly than vertical changes, which were best detected by NMR. To allow for comparisons across different lithologies and depths, resistivity measurements were first log transformed to produce a more normal distribution, then classed by depth and formation and assigned standardized scores using the mean and standard deviation for those classes. To determine the typical appearance of wet areas, points in the near surface were classed as wet or dry based on proximity to surface water. Logistic regression was used to determine the probability that points with a given standardized score were wet. Where a relationship existed between proximity to surface water and conductivity, this information was translated into a map of groundwater distribution at greater depths. NMR soundings provided quantitative measurements of water content, which were used as known points within these horizontal maps to determine the actual water levels being detected.

  18. Statistics of geophysical activity in Nigeria (1975 1984)

    NASA Astrophysics Data System (ADS)

    Umo, A. J.; Ajakaiye, D. E.

    1993-11-01

    Statistics on geophysical activities in Nigeria for the ten-year period (1975-1984) was compiled mainly from questionnaires distributed to government and private agencies, oil and mining companies, and universities which engage in groundwater, petroleum and mineral exploration, engineering and research work. Similar studies had been done worldwide by Epsey (1975, 1976, 1977) and Whitmire (1978). From the statistics, it was deduced that electrical resistivity, magnetic, seismic, radiometric, gravity, airborne and ground magnetic survey methods are the main geophysical techniques used which resulted in the discovery of some of the natural resources (oil, gas, minerals and groundwater) buried a few kilometers below the Nigerian soil. Airborne and ground magnetic surveys have been carried out by at least two government agencies, namely: the Geological Survey of Nigeria and Nigerian Steel Council. The compilation also reveals that a greater part of geophysical and drilling activities of operating oil companies is currently concentrated in the sedimentary basins, mainly the oil-rich Niger Delta and near offshore areas. From the available statistics, at least three companies, the National Steel Council, the Geological Survey of Nigeria, and Kano State Water Resources Engineering and Construction Agency have employed geophysical methods for engineering.

  19. AUTOMATED LEAK DETECTION OF BURIED TANKS USING GEOPHYSICAL METHODS AT THE HANFORD NUCLEAR SITE

    SciTech Connect

    CALENDINE S; SCHOFIELD JS; LEVITT MT; FINK JB; RUCKER DF

    2011-03-30

    At the Hanford Nuclear Site in Washington State, the Department of Energy oversees the containment, treatment, and retrieval of liquid high-level radioactive waste. Much of the waste is stored in single-shelled tanks (SSTs) built between 1943 and 1964. Currently, the waste is being retrieved from the SSTs and transferred into newer double-shelled tanks (DSTs) for temporary storage before final treatment. Monitoring the tanks during the retrieval process is critical to identifying leaks. An electrically-based geophysics monitoring program for leak detection and monitoring (LDM) has been successfully deployed on several SSTs at the Hanford site since 2004. The monitoring program takes advantage of changes in contact resistance that will occur when conductive tank liquid leaks into the soil. During monitoring, electrical current is transmitted on a number of different electrode types (e.g., steel cased wells and surface electrodes) while voltages are measured on all other electrodes, including the tanks. Data acquisition hardware and software allow for continuous real-time monitoring of the received voltages and the leak assessment is conducted through a time-series data analysis. The specific hardware and software combination creates a highly sensitive method of leak detection, complementing existing drywell logging as a means to detect and quantify leaks. Working in an industrial environment such as the Hanford site presents many challenges for electrical monitoring: cathodic protection, grounded electrical infrastructure, lightning strikes, diurnal and seasonal temperature trends, and precipitation, all of which create a complex environment for leak detection. In this discussion we present examples of challenges and solutions to working in the tank farms of the Hanford site.

  20. Hydrogeophysical characterization of anisotropy in the Biscayne Aquifer using geophysical methods

    NASA Astrophysics Data System (ADS)

    Yeboah-Forson, Albert

    The anisotropy of the Biscayne Aquifer which serves as the source of potable water for Miami-Dade County was investigated by applying geophysical methods. Electrical resistivity imaging, self potential and ground penetration radar techniques were employed in both regional and site specific studies. In the regional study, electrical anisotropy and resistivity variation with depth were investigated with azimuthal square array measurements at 13 sites. The observed coefficient of electrical anisotropy ranged from 1.01 to 1.36. The general direction of measured anisotropy is uniform for most sites and trends W-E or SE-NW irrespective of depth. Measured electrical properties were used to estimate anisotropic component of the secondary porosity and hydraulic anisotropy which ranged from 1 to 11% and 1.18 to 2.83 respectively. 1-D sounding analysis was used to models the variation of formation resistivity with depth. Resistivities decreased from NW (close to the margins of the everglades) to SE on the shores of Biscayne Bay. Porosity calculated from Archie's law, ranged from 18 to 61% with higher values found along the ridge. Higher anisotropy, porosities and hydraulic conductivities were on the Atlantic Coastal Ridge and lower values at low lying areas west of the ridge. The cause of higher anisotropy and porosity is attributed to higher dissolution rates of the oolitic facies of the Miami Formation composing the ridge. The direction of minimum resistivity from this study is similar to the predevelopment groundwater flow direction indicated in published modeling studies. Detailed investigations were carried out to evaluate higher anisotropy at West Perrine Park located on the ridge and Snapper Creek Municipal well field where the anisotropy trend changes with depth. The higher anisotropy is attributed to the presence of solution cavities oriented in the E-SE direction on the ridge. Similarly, the change in hydraulic anisotropy at the well field might be related to

  1. Integrating Geophysics, Geology, and Hydrology for Enhanced Hydrogeological Modeling

    NASA Astrophysics Data System (ADS)

    Auken, E.

    2012-12-01

    Geophysical measurements are important for providing information on the geological structure to hydrological models. Regional scale surveys, where several watersheds are mapped at the same time using helicopter borne transient electromagnetic, results in a geophysical model with a very high lateral and vertical resolution of the geological layers. However, there is a bottleneck when it comes to integrating the information from the geophysical models into the hydrological model. This transformation is difficult, because there is not a simple relationship between the hydraulic conductivity needed for the hydrological model and the electrical conductivity measured by the geophysics. In 2012 the Danish Council for Strategic Research has funded a large research project focusing on the problem of integrating geophysical models into hydrological models. The project involves a number of Danish research institutions, consulting companies, a water supply company, as well as foreign partners, USGS (USA), TNO (Holland) and CSIRO (Australia). In the project we will: 1. Use statistical methods to describe the spatial correlation between the geophysical and the lithological/hydrological data; 2. Develop semi-automatic or automatic methods for transforming spatially sampled geophysical data into geological- and/or groundwater-model parameter fields; 3. Develop an inversion method for large-scale geophysical surveys in which the model space is concordant with the hydrological model space 4. Demonstrate the benefits of spatially distributed geophysical data for informing and updating groundwater models and increasing the predictive power of management scenarios. 5. Develop a new receiver system for Magnetic Resonance Sounding data and further enhance the resolution capability of data from the SkyTEM system. 6. In test areas in Denmark, Holland, USA and Australia we will use data from existing airborne geophysical data, hydrological and geological data and also collect new airborne

  2. Comparison of Air Impaction and Electrostatic Dust Collector Sampling Methods to Assess Airborne Fungal Contamination in Public Buildings.

    PubMed

    Normand, Anne-Cécile; Ranque, Stéphane; Cassagne, Carole; Gaudart, Jean; Sallah, Kankoé; Charpin, Denis-André; Piarroux, Renaud

    2016-03-01

    Many ailments can be linked to exposure to indoor airborne fungus. However, obtaining a precise measurement of airborne fungal levels is complicated partly due to indoor air fluctuations and non-standardized techniques. Electrostatic dust collector (EDC) sampling devices have been used to measure a wide range of airborne analytes, including endotoxins, allergens, β-glucans, and microbial DNA in various indoor environments. In contrast, viable mold contamination has only been assessed in highly contaminated environments such as farms and archive buildings. This study aimed to assess the use of EDCs, compared with repeated air-impactor measurements, to assess airborne viable fungal flora in moderately contaminated indoor environments. Indoor airborne fungal flora was cultured from EDCs and daily air-impaction samples collected in an office building and a daycare center. The quantitative fungal measurements obtained using a single EDC significantly correlated with the cumulative measurement of nine daily air impactions. Both methods enabled the assessment of fungal exposure, although a few differences were observed between the detected fungal species and the relative quantity of each species. EDCs were also used over a 32-month period to monitor indoor airborne fungal flora in a hospital office building, which enabled us to assess the impact of outdoor events (e.g. ground excavations) on the fungal flora levels on the indoor environment. In conclusion, EDC-based measurements provided a relatively accurate profile of the viable airborne flora present during a sampling period. In particular, EDCs provided a more representative assessment of fungal levels compared with single air-impactor sampling. The EDC technique is also simpler than performing repetitive air-impaction measures over the course of several consecutive days. EDC is a versatile tool for collecting airborne samples and was efficient for measuring mold levels in indoor environments.

  3. Application of advanced geophysical logging methods in the characterization of a fractured-sedimentary bedrock aquifer, Ventura County, California

    USGS Publications Warehouse

    Williams, John H.; Lane, Jr., John W.; Singha, Kamini; Haeni, F. Peter

    2002-01-01

    An integrated suite of advanced geophysical logging methods was used to characterize the geology and hydrology of three boreholes completed in fractured-sedimentary bedrock in Ventura County, California. The geophysical methods included caliper, gamma, electromagnetic induction, borehole deviation, optical and acoustic televiewer, borehole radar, fluid resistivity, temperature, and electromagnetic flowmeter. The geophysical logging 1) provided insights useful for the overall geohydrologic characterization of the bedrock and 2) enhanced the value of information collected by other methods from the boreholes including core-sample analysis, multiple-level monitoring, and packer testing. The logged boreholes, which have open intervals of 100 to 200 feet, penetrate a sequence of interbedded sandstone and mudstone with bedding striking 220 to 250 degrees and dipping 15 to 40 degrees to the northwest. Fractures intersected by the boreholes include fractures parallel to bedding and fractures with variable strike that dip moderately to steeply. Two to three flow zones were detected in each borehole. The flow zones consist of bedding-parallel or steeply dipping fractures or a combination of bedding-parallel fractures and moderately to steeply dipping fractures. About 75 to more than 90 percent of the measured flow under pumped conditions was produced by only one of the flow zones in each borehole.

  4. A new measurement method for separating airborne and structureborne noise radiated by aircraft type panels

    NASA Technical Reports Server (NTRS)

    Mcgary, M. C.

    1982-01-01

    The theoretical basis for and experimental validation of a measurement method for separating airborne and structure borne noise radiated by aircraft type panels are presented. An extension of the two microphone, cross spectral, acoustic intensity method combined with existing theory of sound radiation of thin shell structures of various designs, is restricted to the frequency range below the coincidence frequency of the structure. Consequently, the method lends itself to low frequency noise problems such as propeller harmonics. Both an aluminum sheet and two built up aircraft panel designs (two aluminum panels with frames and stringers) with and without added damping were measured. Results indicate that the method is quick, reliable, inexpensive, and can be applied to thin shell structures of various designs.

  5. Method of airborne SAR image match integrating multi-information for block adjustment

    NASA Astrophysics Data System (ADS)

    Yang, S. C.; Huang, G. M.; Zhao, Z.; Lu, L. J.

    2015-06-01

    For the automation of SAR image Block Adjustment, this paper proposed a method of SAR image matching integrating multiinformation. It takes full advantage of SAR image geometric information, feature information, gray-related information and external auxiliary terrain information for SAR image matching. And then Image Tie Points (ITPs) of Block Adjustment can be achieved automatically. The main parts of extracting ITPs automatically include: First, SAR images were rectified geometrically based on the geometric information and external auxiliary terrain information (existed DEM) before match. Second, ground grid points with a certain interval can be get in the block area and approximate ITPs were acquired based on external auxiliary terrain information. Then match reference point was extracted for homologous image blocks with Harris feature detection operator and ITPs were obtained with pyramid matching based on gray-related information. At last, ITPs were transferred from rectified images to original SAR images and used in block adjustment. In the experiment, X band airborne SAR images acquired by Chinese airborne SAR system - CASMSAR system were used to make up the block. The result had showed that the method is effective for block adjustment of SAR data.

  6. Efficient method for the determination of image correspondence in airborne applications using inertial sensors.

    PubMed

    Woods, Matthew; Katsaggelos, Aggelos

    2013-01-01

    This paper presents a computationally efficient method for the measurement of a dense image correspondence vector field using supplementary data from an inertial navigation sensor (INS). The application is suited to airborne imaging systems, such as an unmanned air vehicle, where size, weight, and power restrictions limit the amount of onboard processing available. The limited processing will typically exclude the use of traditional, but computationally expensive, optical flow and block matching algorithms, such as Lucas-Kanade, Horn-Schunck, or the adaptive rood pattern search. Alternatively, the measurements obtained from an INS, on board the platform, lead to a closed-form solution to the correspondence field. Airborne platforms are well suited to this application because they already possess INSs and global positioning systems as part of their existing avionics package. We derive the closed-form solution for the image correspondence vector field based on the INS data. We then show, through both simulations and real flight data, that the closed-form inertial sensor solution outperforms traditional optical flow and block matching methods.

  7. Environmental and Engineering Geophysics

    NASA Astrophysics Data System (ADS)

    Sharma, Prem V.

    1997-12-01

    Geophysical imaging methods provide solutions to a wide variety of environmental and engineering problems: protection of soil and groundwater from contamination; disposal of chemical and nuclear waste; geotechnical site testing; landslide and ground subsidence hazard detection; location of archaeological artifacts. This book comprehensively describes the theory, data acquisition and interpretation of all of the principal techniques of geophysical surveying: gravity, magnetic, seismic, self-potential, resistivity, induced polarization, electromagnetic, ground-probing radar, radioactivity, geothermal, and geophysical borehole logging. Each chapter is supported by a large number of richly illustrated case histories. This book will prove to be a valuable textbook for senior undergraduates and postgraduates in environmental and applied geophysics, a supplementary course book for students of geology, engineering geophysics, civil and mining engineering, and a reference work for professional earth scientists, engineers and town planners.

  8. A Hydrologic-geophysical Method for Characterizing Flow and Transport Processes Within The Vadose Zone

    SciTech Connect

    David Alumbaugh; Douglas LaBrecque; James Brainard; T.C. Yeh

    2004-01-22

    The primary purpose of this project was to employ two geophysical imaging techniques, electrical resistivity tomography and cross-borehole ground penetrating radar, to image a controlled infiltration of a saline tracer under unsaturated flow conditions. The geophysical techniques have been correlated to other more traditional hydrologic measurements including neutron moisture measurements and induction conductivity logs. Images that resulted during two successive infiltrations indicate the development of what appear to be preferential pathways through the finer grained materials, although the results could also be produced by cationic capture of free ions in clays. In addition the site as well as the developing solute plume exhibits electrical anisotropy which is likely related to flow properties. However the geologic significance of this phenomenon is still under investigation.

  9. Geophysical methods applied to fault characterization and earthquake potential assessment in the Lower Tagus Valley, Portugal

    NASA Astrophysics Data System (ADS)

    Carvalho, João; Cabral, João; Gonçalves, Rui; Torres, Luís; Mendes-Victor, Luís

    2006-06-01

    The study region is located in the Lower Tagus Valley, central Portugal, and includes a large portion of the densely populated area of Lisbon. It is characterized by a moderate seismicity with a diffuse pattern, with historical earthquakes causing many casualties, serious damage and economic losses. Occurrence of earthquakes in the area indicates the presence of seismogenic structures at depth that are deficiently known due to a thick Cenozoic sedimentary cover. The hidden character of many of the faults in the Lower Tagus Valley requires the use of indirect methodologies for their study. This paper focuses on the application of high-resolution seismic reflection method for the detection of near-surface faulting on two major tectonic structures that are hidden under the recent alluvial cover of the Tagus Valley, and that have been recognized on deep oil-industry seismic reflection profiles and/or inferred from the surface geology. These are a WNW-ESE-trending fault zone located within the Lower Tagus Cenozoic basin, across the Tagus River estuary (Porto Alto fault), and a NNE-SSW-trending reverse fault zone that borders the Cenozoic Basin at the W (Vila Franca de Xira-Lisbon fault). Vertical electrical soundings were also acquired over the seismic profiles and the refraction interpretation of the reflection data was carried out. According to the interpretation of the collected data, a complex fault pattern disrupts the near surface (first 400 m) at Porto Alto, affecting the Upper Neogene and (at least for one fault) the Quaternary, with a normal offset component. The consistency with the previous oil-industry profiles interpretation supports the location and geometry of this fault zone. Concerning the second structure, two major faults were detected north of Vila Franca de Xira, supporting the extension of the Vila Franca de Xira-Lisbon fault zone northwards. One of these faults presents a reverse geometry apparently displacing Holocene alluvium. Vertical offsets

  10. Application of real-time PCR for total airborne bacterial assessment: Comparison with epifluorescence microscopy and culture-dependent methods

    NASA Astrophysics Data System (ADS)

    Rinsoz, Thomas; Duquenne, Philippe; Greff-Mirguet, Guylaine; Oppliger, Anne

    Traditional culture-dependent methods to quantify and identify airborne microorganisms are limited by factors such as short-duration sampling times and inability to count non-culturable or non-viable bacteria. Consequently, the quantitative assessment of bioaerosols is often underestimated. Use of the real-time quantitative polymerase chain reaction (Q-PCR) to quantify bacteria in environmental samples presents an alternative method, which should overcome this problem. The aim of this study was to evaluate the performance of a real-time Q-PCR assay as a simple and reliable way to quantify the airborne bacterial load within poultry houses and sewage treatment plants, in comparison with epifluorescence microscopy and culture-dependent methods. The estimates of bacterial load that we obtained from real-time PCR and epifluorescence methods, are comparable, however, our analysis of sewage treatment plants indicate these methods give values 270-290 fold greater than those obtained by the "impaction on nutrient agar" method. The culture-dependent method of air impaction on nutrient agar was also inadequate in poultry houses, as was the impinger-culture method, which gave a bacterial load estimate 32-fold lower than obtained by Q-PCR. Real-time quantitative PCR thus proves to be a reliable, discerning, and simple method that could be used to estimate airborne bacterial load in a broad variety of other environments expected to carry high numbers of airborne bacteria.

  11. Detection of airborne bacteria in a German turkey house by cultivation-based and molecular methods.

    PubMed

    Fallschissel, Kerstin; Klug, Kerstin; Kämpfer, Peter; Jäckel, Udo

    2010-11-01

    Today's large-scale poultry production with densely stocked and enclosed production buildings is often accompanied by very high concentrations of airborne microorganisms leading to a clear health hazard for employees working in such environments. Depending on the expected exposure to microorganisms, work has to be performed under occupational safety conditions. In this study, turkey houses bioaerosols were investigated by cultivation-based and molecular methods in parallel to determine the concentrations and the composition of bacterial community. Results obtained with the molecular approach showed clearly its applicability for qualitative exposure measurements. With both, cultivation-based and molecular methods species of microorganism with a potential health risk for employees (Acinetobacter johnsonii, Aerococcus viridans, Pantoea agglomerans, and Shigella flexneri) were identified. These results underline the necessity of adequate protection measures, including the recommendation to wear breathing masks during work in poultry houses.

  12. Airborne geophysical surveys used to delineate geological features associated with the M5.8 August 23, 2011 earthquake in Louisa County, Virginia

    NASA Astrophysics Data System (ADS)

    Shah, A. K.; Horton, J. W.; Gilmer, A. K.

    2012-12-01

    The M5.8 August 23, 2011 Louisa County, VA intraplate earthquake was felt by more people than any other in U.S. history not only because of population density, but also because of the associated geology. However, because limited bedrock exposures pose a challenge to geologic mapping efforts and the earthquake hypocenter is located at a depth of ~6 km, many questions remain. Potential field and gamma-ray spectrometry data thus provide key tools for imaging and understanding both shallow and deep subsurface geologic features. In July 2012, the USGS commissioned a high-resolution magnetic, gravity, and radiometric (gamma-ray spectrometry) survey over a 20 km x 25 km area covering the epicenters of the Louisa County earthquake and its aftershocks. The surveys were flown with 200-m line spacing from an altitude of ~120 m above ground, providing up to a 20-fold improvement over regional magnetic and radiometric coverage. Gravity was measured using Sander Geophysics' AIRGrav system, capable of resolving anomalies as narrow as 800 m for the given survey configuration; in most parts of the survey area the spacing of ground stations is ~10-20 stations per 100 km2. Preliminary magnetic and radiometric data show numerous NE-trending linear anomalies within this part of the Appalachian Piedmont Province. These metamorphic and igneous rocks exhibit 200-500 nT magnetic anomalies of width 300-1000 km that are likely to be generated by contrasts between various metavolcanic and metasedimentary rocks such as magnetite-bearing quartzites and felsic to mafic gneisses. Magnetic lows and radiometric highs are observed over several granitoid intrusive bodies such as the Ellisville pluton, the Falmouth Intrusive Suite, and a Paleozoic pegmatite belt. Derivative magnetic maps delineate numerous thin (< 250 m wide) N- NNW-trending linear anomalies, suggesting that Jurassic diabase dikes are much more common in this area than previously mapped. Radiometric data mostly correlate with mapped

  13. Investigating the Greenland firn aquifer near Helheim Glacier based on geophysical noninvasive methods and in situ measurements

    NASA Astrophysics Data System (ADS)

    Miège, C.; Koenig, L.; Forster, R. R.; Miller, O. L.; Solomon, D. K.; Legchenko, A.; Schmerr, N. C.; Montgomery, L. N.; Brucker, L.

    2015-12-01

    Prior to the onset of seasonal surface melt, widespread perennial aquifers are detected at an average depth of 22 m below the snow surface in the firn of the Greenland ice sheet from airborne radar data. With an elevation range of ~1200-2000 m, the aquifers are mainly located within the percolation zone of the southern and southeastern parts of the ice sheet, in high snow accumulation regions. The impact of the aquifer on Greenland ice sheet hydrology and the direct (or indirect) contribution to sea-level rise remain unconstrained and require further attention. Our study is located on the upper portion of Helheim Glacier in SE Greenland, ~50 km west of the glacier calving front. We first used repeated airborne radar data collected by CReSIS to infer the presence of the firn over the last two decades from missing bed echoes. For 1993-2008, the aquifer remained relatively stable, after 2008 it expanded to higher elevations, and after spring 2012, drainage of its lower-elevation portion is suspected. Based on these initial insights, recent fieldwork was carried out along the surveyed radar line, following an elevation gradient. Geophysical investigation includes seismic refraction and magnetic resonance soundings to complement the radar data and to provide constraints on the base of the aquifer, water volume, and the transition from water-saturated firn to ice. In addition, piezometers and data-logging stations were deployed at point locations to measure hydraulic conductivity, water table vertical fluctuations, and firn temperature. We report on the different techniques used, initial observations made, and present some preliminary interpretations. Water appears to flow laterally in a highly-permeable unconfined aquifer, topographically driven by ice-sheet surface undulations until water encounters local sinks like crevasses. The aquifer impacts on the ice sheet are numerous, including firn densification, alteration of the ice thermal state, and water from the aquifer

  14. Geophysics in INSPIRE

    NASA Astrophysics Data System (ADS)

    Sőrés, László

    2013-04-01

    INSPIRE is a European directive to harmonize spatial data in Europe. Its' aim is to establish a transparent, multidisciplinary network of environmental information by using international standards and OGC web services. Spatial data themes defined in the annex of the directive cover 34 domains that are closely bundled to environment and spatial information. According to the INSPIRE roadmap all data providers must setup discovery, viewing and download services and restructure data stores to provide spatial data as defined by the underlying specifications by 2014 December 1. More than 3000 institutions are going to be involved in the progress. During the data specification process geophysics as an inevitable source of geo information was introduced to Annex II Geology. Within the Geology theme Geophysics is divided into core and extended model. The core model contains specifications for legally binding data provisioning and is going to be part of the Implementation Rules of the INSPIRE directives. To minimize the work load of obligatory data transformations the scope of the core model is very limited and simple. It covers the most essential geophysical feature types that are relevant in economic and environmental context. To fully support the use cases identified by the stake holders the extended model was developed. It contains a wide range of spatial object types for geophysical measurements, processed and interpreted results, and wrapper classes to help data providers in using the Observation and Measurements (O&M) standard for geophysical data exchange. Instead of introducing the traditional concept of "geophysical methods" at a high structural level the data model classifies measurements and geophysical models based on their spatial characteristics. Measurements are classified as geophysical station (point), geophysical profile (curve) and geophysical swath (surface). Generic classes for processing results and interpretation models are curve model (1D), surface

  15. Preventing Airborne Disease Transmission: Review of Methods for Ventilation Design in Health Care Facilities

    PubMed Central

    Aliabadi, Amir A.; Rogak, Steven N.; Bartlett, Karen H.; Green, Sheldon I.

    2011-01-01

    Health care facility ventilation design greatly affects disease transmission by aerosols. The desire to control infection in hospitals and at the same time to reduce their carbon footprint motivates the use of unconventional solutions for building design and associated control measures. This paper considers indoor sources and types of infectious aerosols, and pathogen viability and infectivity behaviors in response to environmental conditions. Aerosol dispersion, heat and mass transfer, deposition in the respiratory tract, and infection mechanisms are discussed, with an emphasis on experimental and modeling approaches. Key building design parameters are described that include types of ventilation systems (mixing, displacement, natural and hybrid), air exchange rate, temperature and relative humidity, air flow distribution structure, occupancy, engineered disinfection of air (filtration and UV radiation), and architectural programming (source and activity management) for health care facilities. The paper describes major findings and suggests future research needs in methods for ventilation design of health care facilities to prevent airborne infection risk. PMID:22162813

  16. Performance assessment of onboard and scene-based methods for Airborne Prism Experiment spectral characterization.

    PubMed

    D'Odorico, Petra; Guanter, Luis; Schaepman, Michael E; Schläpfer, Daniel

    2011-08-20

    Accurate spectral calibration of airborne and spaceborne imaging spectrometers is essential for proper preprocessing and scientific exploitation of high spectral resolution measurements of the land and atmosphere. A systematic performance assessment of onboard and scene-based methods for in-flight monitoring of instrument spectral calibration is presented for the first time in this paper. Onboard and ground imaging data were collected at several flight altitudes using the Airborne Prism Experiment (APEX) imaging spectrometer. APEX is equipped with an in-flight characterization (IFC) facility allowing the evaluation of radiometric, spectral, and geometric system properties, both in-flight and on-ground for the full field of view. Atmospheric and onboard filter spectral features present in at-sensor radiances are compared with the same features in reference transmittances convolved to varying instrument spectral configurations. A spectrum-matching algorithm, taking advantage of the high sensitivity of measurements around sharp spectral features toward spectrometer spectral performance, is used to retrieve channel center wavelength and bandwidth parameters. Results showed good agreement between spectral parameters estimated using onboard IFC and ground imaging data. The average difference between estimates obtained using the O(2) and H(2)O features and those obtained using the corresponding filter features amounted to about 0.3 nm (0.05 of a spectral pixel). A deviation from the nominal laboratory instrument spectral calibration and an altitude-dependent performance was additionally identified. The relatively good agreement between estimates obtained by the two approaches in similar spectral windows suggests they can be used in a complementary fashion: while the method relying on atmospheric features can be applied without the need for dedicated calibration acquisitions, the IFC allows assessment at user-selectable wavelength positions by custom filters as well as for

  17. Airborne Gravity Survey and Ground Gravity in Afghanistan: A Website for Distribution of Data

    USGS Publications Warehouse

    Abraham, Jared D.; Anderson, Eric D.; Drenth, Benjamin J.; Finn, Carol A.; Kucks, Robert P.; Lindsay, Charles R.; Phillips, Jeffrey D.; Sweeney, Ronald E.

    2008-01-01

    Afghanistan?s geologic setting suggests significant natural resource potential. Although important mineral deposits and petroleum resources have been identified, much of the country?s potential remains unknown. Airborne geophysical surveys are a well- accepted and cost-effective method for remotely obtaining information of the geological setting of an area. A regional airborne geophysical survey was proposed due to the security situation and the large areas of Afghanistan that have not been covered using geophysical exploration methods. Acting upon the request of the Islamic Republic of Afghanistan Ministry of Mines, the U.S. Geological Survey contracted with the U.S. Naval Research Laboratory to jointly conduct an airborne geophysical and remote sensing survey of Afghanistan. Data collected during this survey will provide basic information for mineral and petroleum exploration studies that are important for the economic development of Afghanistan. Additionally, use of these data is broadly applicable in the assessment of water resources and natural hazards, the inventory and planning of civil infrastructure and agricultural resources, and the construction of detailed maps. The U.S. Geological Survey is currently working in cooperation with the U.S. Agency of International Development to conduct resource assessments of the country of Afghanistan for mineral, energy, coal, and water resources, and to assess geologic hazards. These geophysical and remote sensing data will be used directly in the resource and hazard assessments.

  18. Exploration Geophysics

    ERIC Educational Resources Information Center

    Savit, Carl H.

    1978-01-01

    Expansion of activity and confirmation of new technological directions characterized several fields of exploration geophysics in 1977. Advances in seismic-reflection exploration have been especially important. (Author/MA)

  19. Exploration Geophysics

    ERIC Educational Resources Information Center

    Espey, H. R.

    1977-01-01

    Describes geophysical techniques such as seismic, gravity, and magnetic surveys of offshare acreage, and land-data gathering from a three-dimensional representation made from closely spaced seismic lines. (MLH)

  20. Geophysical methods to support correct water sampling locations for salt dilution gauging

    NASA Astrophysics Data System (ADS)

    Comina, C.; Lasagna, M.; De Luca, D. A.; Sambuelli, L.

    2014-05-01

    To improve water management design, particularly in irrigation areas, it is important to evaluate the baseline state of the water resources, including canal discharge. Discharge measurements, using salt dilution gauging, are a traditional and well-documented technique. The complete mixing of salt used for dilution gauging is required for reliable measurements; this condition is difficult to test or verify and, if not fulfilled, is the largest source of uncertainty in the discharge calculation. In this paper, a geophysical technique (FERT, Fast Electrical Resistivity Tomography) is proposed for imaging the distribution of the salt plume used for dilution gauging at every point along a sampling cross-section. In this way, it is possible to check whether complete mixing has occurred. If the mixing is not complete, the image created by FERT can also provide guidance for selecting water-sampling locations in the sampling cross-section. A water multi-sampling system prototype for the simultaneous sampling of canal water at different points within the cross-section, aimed to potentially take into account concentration variability, is also proposed and tested. Preliminary results of a single test with salt dilution gauging and FERT in a real case are reported. The results show that imaging the passage of the salt plume is possible by means of geophysical controls and that this can potentially help in the selection of water sampling points.

  1. Intercomparison of single-frequency methods for retrieving a vertical rain profile from airborne or spaceborne radar data

    NASA Technical Reports Server (NTRS)

    Iguchi, Toshio; Meneghini, Robert

    1994-01-01

    This paper briefly reviews several single-frequency rain profiling methods for an airborne or spaceborne radar. The authors describe the different methods from a unified point of view starting from the basic differential equation. This facilitates the comparisons between the methods and also provides a better understanding of the physical and mathematical basis of the methods. The application of several methods to airborne radar data taken during the Convective and Precipitation/Electrification Experiment is shown. Finally, the authors consider a hybrid method that provides a smooth transition between the Hitschfeld-Bordan method, which performs well at low attenuations, and the surface reference method, for which the relative error decreases with increasing path attenuation.

  2. Notes on interpretation of geophysical data over areas of mineralization in Afghanistan

    USGS Publications Warehouse

    Drenth, Benjamin J.

    2011-01-01

    Afghanistan has the potential to contain substantial metallic mineral resources. Although valuable mineral deposits have been identified, much of the country's potential remains unknown. Geophysical surveys, particularly those conducted from airborne platforms, are a well-accepted and cost-effective method for obtaining information on the geological setting of a given area. This report summarizes interpretive findings from various geophysical surveys over selected mineral targets in Afghanistan, highlighting what existing data tell us. These interpretations are mainly qualitative in nature, because of the low resolution of available geophysical data. Geophysical data and simple interpretations are included for these six areas and deposit types: (1) Aynak: Sedimentary-hosted copper; (2) Zarkashan: Porphyry copper; (3) Kundalan: Porphyry copper; (4) Dusar Shaida: Volcanic-hosted massive sulphide; (5) Khanneshin: Carbonatite-hosted rare earth element; and (6) Chagai Hills: Porphyry copper.

  3. Roof Reconstruction from Airborne Laser Scanning Data Based on Image Processing Methods

    NASA Astrophysics Data System (ADS)

    Goebbels, S.; Pohle-Fröhlich, R.

    2016-06-01

    The paper presents a new data-driven approach to generate CityGML building models from airborne laser scanning data. The approach is based on image processing methods applied to an interpolated height map and avoids shortcomings of established methods for plane detection like Hough transform or RANSAC algorithms on point clouds. The improvement originates in an interpolation algorithm that generates a height map from sparse point cloud data by preserving ridge lines and step edges of roofs. Roof planes then are detected by clustering the height map's gradient angles, parameterizations of planes are estimated and used to filter out noise around ridge lines. On that basis, a raster representation of roof facets is generated. Then roof polygons are determined from region outlines, connected to a roof boundary graph, and simplified. Whereas the method is not limited to churches, the method's performance is primarily tested for church roofs of the German city of Krefeld because of their complexity. To eliminate inaccuracies of spires, contours of towers are detected additionally, and spires are rendered as solids of revolution. In our experiments, the new data-driven method lead to significantly better building models than the previously applied model-driven approach.

  4. A wavelet-based baseline drift correction method for grounded electrical source airborne transient electromagnetic signals

    NASA Astrophysics Data System (ADS)

    Wang, Yuan 1Ji, Yanju 2Li, Suyi 13Lin, Jun 12Zhou, Fengdao 1Yang, Guihong

    2013-09-01

    A grounded electrical source airborne transient electromagnetic (GREATEM) system on an airship enjoys high depth of prospecting and spatial resolution, as well as outstanding detection efficiency and easy flight control. However, the movement and swing of the front-fixed receiving coil can cause severe baseline drift, leading to inferior resistivity image formation. Consequently, the reduction of baseline drift of GREATEM is of vital importance to inversion explanation. To correct the baseline drift, a traditional interpolation method estimates the baseline `envelope' using the linear interpolation between the calculated start and end points of all cycles, and obtains the corrected signal by subtracting the envelope from the original signal. However, the effectiveness and efficiency of the removal is found to be low. Considering the characteristics of the baseline drift in GREATEM data, this study proposes a wavelet-based method based on multi-resolution analysis. The optimal wavelet basis and decomposition levels are determined through the iterative comparison of trial and error. This application uses the sym8 wavelet with 10 decomposition levels, and obtains the approximation at level-10 as the baseline drift, then gets the corrected signal by removing the estimated baseline drift from the original signal. To examine the performance of our proposed method, we establish a dipping sheet model and calculate the theoretical response. Through simulations, we compare the signal-to-noise ratio, signal distortion, and processing speed of the wavelet-based method and those of the interpolation method. Simulation results show that the wavelet-based method outperforms the interpolation method. We also use field data to evaluate the methods, compare the depth section images of apparent resistivity using the original signal, the interpolation-corrected signal and the wavelet-corrected signal, respectively. The results confirm that our proposed wavelet-based method is an

  5. Modeling aboveground tree woody biomass using national-scale allometric methods and airborne lidar

    NASA Astrophysics Data System (ADS)

    Chen, Qi

    2015-08-01

    Estimating tree aboveground biomass (AGB) and carbon (C) stocks using remote sensing is a critical component for understanding the global C cycle and mitigating climate change. However, the importance of allometry for remote sensing of AGB has not been recognized until recently. The overarching goals of this study are to understand the differences and relationships among three national-scale allometric methods (CRM, Jenkins, and the regional models) of the Forest Inventory and Analysis (FIA) program in the U.S. and to examine the impacts of using alternative allometry on the fitting statistics of remote sensing-based woody AGB models. Airborne lidar data from three study sites in the Pacific Northwest, USA were used to predict woody AGB estimated from the different allometric methods. It was found that the CRM and Jenkins estimates of woody AGB are related via the CRM adjustment factor. In terms of lidar-biomass modeling, CRM had the smallest model errors, while the Jenkins method had the largest ones and the regional method was between. The best model fitting from CRM is attributed to its inclusion of tree height in calculating merchantable stem volume and the strong dependence of non-merchantable stem biomass on merchantable stem biomass. This study also argues that it is important to characterize the allometric model errors for gaining a complete understanding of the remotely-sensed AGB prediction errors.

  6. Near-surface geophysical methods for investigating the Buyukcekmece landslide in Istanbul, Turkey

    NASA Astrophysics Data System (ADS)

    Yalcinkaya, Esref; Alp, Hakan; Ozel, Oguz; Gorgun, Ethem; Martino, Salvatore; Lenti, Luca; Bourdeau, Celine; Bigarre, Pascal; Coccia, Stella

    2016-11-01

    In this study, near-surface geophysical techniques are used to investigate the physical characteristics of the Buyukcekmece landslide (Istanbul, Turkey). The Buyukcekmece landslide has continuous activity at a low velocity and is classified as a complex mechanism. It includes rototranslational parts, several secondary scarps, several landslide terraces, and evidence of two earth flows. It mainly develops in the clayey layers of the Danismen Formation. According to our findings, P-wave velocities ranging from 300 m/s to 2400 m/s do not provide notable discrimination between sliding mass and stable soil. They show variations in blocks reflecting a complex structure. We obtained the S-wave velocity structure of the landslide up to 80 m by combining the analysis of MASW and ReMi. It is clear that S-wave velocities are lower in the landslide compared to those of the stable area. Identical S-wave velocities for the entire area at depths higher than 60 m may point out the maximum thickness of the landslide mass. Resonance frequencies obtained from the H/V analysis of the landslide area are generally higher than those of the stable area. The depths computed by using an empirical relationship between the resonance frequency and the soil thickness point out the failure surfaces from 10 to 50 m moving downslope from the landslide crown area. The resistivity values within the landslide are generally lower than 30 Ω m, i.e., a typical value for remolded clayey debris. The geophysical results reflect an overview of the geological model, but the complexity of the landslide makes it difficult to map the landslide structure in detail.

  7. Investigating groundwater flow paths within proglacial moraine using multiple geophysical methods

    NASA Astrophysics Data System (ADS)

    McClymont, Alastair F.; Roy, James W.; Hayashi, Masaki; Bentley, Laurence R.; Maurer, Hansruedi; Langston, Greg

    2011-03-01

    SummaryGroundwater that is stored and slowly released from alpine watersheds plays an important role in sustaining mountain rivers. Yet, little is known about how groundwater flows within typical alpine geological deposits like glacial moraine, talus, and bedrock. Within the Lake O'Hara alpine watershed of the Canadian Rockies, seasonal snowmelt and rain infiltrates into a large complex of glacial moraine and talus deposits before discharging from a series of springs within a relatively confined area of a terminal moraine deposit. In order to understand the shallow subsurface processes that govern how groundwater is routed through this area, we have undertaken a geophysical study on glacial moraine and bedrock over and around the springs. From interpretations of several seismic refraction, ground-penetrating radar (GPR), and electrical resistivity tomography (ERT) profiles, we delineate the topography of bedrock beneath moraine. Although the bedrock is generally flat under central parts of the terminal moraine, we suggest that an exposed slope of bedrock on its eastern side and a ridge of shallow bedrock imaged by ERT data underneath its western margin serves to channel deep groundwater toward the largest spring. Low-electrical-resistivity anomalies identified on ERT images within shallow parts of the moraine indicate the presence of groundwater flowing over shallow bedrock and/or ice. From coincident seismic refraction, GPR and ERT profiles, we interpret an ca. 5-m-thick deep layer of saturated moraine and fractured bedrock. Despite their relatively small storage volumes, we suggest that groundwater flowing through bedrock cracks may provide an important contribution to stream runoff during low-flow periods. The distinct deep and shallow groundwater flow paths that we interpret from geophysical data reconcile with interpretations from previous analyses of hydrograph and water chemistry data from this same area.

  8. A chemical free, nanotechnology-based method for airborne bacterial inactivation using engineered water nanostructures†‡

    PubMed Central

    Pyrgiotakis, Georgios; McDevitt, James; Bordini, Andre; Diaz, Edgar; Molina, Ramon; Watson, Christa; Deloid, Glen; Lenard, Steve; Fix, Natalie; Mizuyama, Yosuke; Yamauchi, Toshiyuki; Brain, Joseph

    2015-01-01

    Airborne pathogens are associated with the spread of infectious diseases and increased morbidity and mortality. Herein we present an emerging chemical free, nanotechnology-based method for airborne pathogen inactivation. This technique is based on transforming atmospheric water vapor into Engineered Water Nano-Structures (EWNS) via electrospray. The generated EWNS possess a unique set of physical, chemical, morphological and biological properties. Their average size is 25 nm and they contain reactive oxygen species (ROS) such as hydroxyl and superoxide radicals. In addition, EWNS are highly electrically charged (10 electrons per particle on average). A link between their electric charge and the reduction of their evaporation rate was illustrated resulting in an extended lifetime (over an hour) at room conditions. Furthermore, it was clearly demonstrated that the EWNS have the ability to interact with and inactivate airborne bacteria. Finally, inhaled EWNS were found to have minimal toxicological effects, as illustrated in an acute in-vivo inhalation study using a mouse model. In conclusion, this novel, chemical free, nanotechnology-based method has the potential to be used in the battle against airborne infectious diseases. PMID:26180637

  9. Geophex Airborne Unmanned Survey System

    SciTech Connect

    Won, I.J.; Keiswetter, D.

    1995-10-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits rapid geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected.

  10. A new method for GPS-based wind speed determinations during airborne volcanic plume measurements

    USGS Publications Warehouse

    Doukas, Michael P.

    2002-01-01

    Begun nearly thirty years ago, the measurement of gases in volcanic plumes is today an accepted technique in volcano research. Volcanic plume measurements, whether baseline gas emissions from quiescent volcanoes or more substantial emissions from volcanoes undergoing unrest, provide important information on the amount of gaseous output of a volcano to the atmosphere. Measuring changes in gas emission rates also allows insight into eruptive behavior. Some of the earliest volcanic plume measurements of sulfur dioxide were made using a correlation spectrometer (COSPEC). The COSPEC, developed originally for industrial pollution studies, is an upward-looking optical spectrometer tuned to the ultraviolet absorption wavelength of sulfur dioxide (Millán and Hoff, 1978). In airborne mode, the COSPEC is mounted in a fixed-wing aircraft and flown back and forth just underneath a volcanic plume, perpendicular to the direction of plume travel (Casadevall and others, 1981; Stoiber and others, 1983). Similarly, for plumes close to the ground, the COSPEC can be mounted in an automobile and driven underneath a plume if a suitable road system is available (Elias and others, 1998). The COSPEC can also be mounted on a tripod and used to scan a volcanic plume from a fixed location on the ground, although the effectiveness of this configuration declines with distance from the plume (Kyle and others, 1990). In the 1990’s, newer airborne techniques involving direct sampling of volcanic plumes with infrared spectrometers and electrochemical sensors were developed in order to measure additional gases such as CO2 and H2S (Gerlach and others, 1997; Gerlach and others, 1999; McGee and others, 2001). These methods involve constructing a plume cross-section from several measurement traverses through the plume in a vertical plane. Newer instruments such as open-path Fourier transform infrared (FTIR) spectrometers are now being used to measure the gases in volcanic plumes mostly from fixed

  11. Parallel Processing Method for Airborne Laser Scanning Data Using a PC Cluster and a Virtual Grid.

    PubMed

    Han, Soo Hee; Heo, Joon; Sohn, Hong Gyoo; Yu, Kiyun

    2009-01-01

    In this study, a parallel processing method using a PC cluster and a virtual grid is proposed for the fast processing of enormous amounts of airborne laser scanning (ALS) data. The method creates a raster digital surface model (DSM) by interpolating point data with inverse distance weighting (IDW), and produces a digital terrain model (DTM) by local minimum filtering of the DSM. To make a consistent comparison of performance between sequential and parallel processing approaches, the means of dealing with boundary data and of selecting interpolation centers were controlled for each processing node in parallel approach. To test the speedup, efficiency and linearity of the proposed algorithm, actual ALS data up to 134 million points were processed with a PC cluster consisting of one master node and eight slave nodes. The results showed that parallel processing provides better performance when the computational overhead, the number of processors, and the data size become large. It was verified that the proposed algorithm is a linear time operation and that the products obtained by parallel processing are identical to those produced by sequential processing. PMID:22574032

  12. Geophysical methods to support correct water sampling locations for salt dilution gauging

    NASA Astrophysics Data System (ADS)

    Comina, C.; Lasagna, M.; De Luca, D. A.; Sambuelli, L.

    2014-08-01

    To improve water management design, particularly in irrigation areas, it is important to evaluate the baseline state of the water resources, including canal discharge. Salt dilution gauging is a traditional and well-documented technique in this respect. The complete mixing of salt used for dilution gauging is required; this condition is difficult to test or verify and, if not fulfilled, is the largest source of uncertainty in the discharge calculation. In this paper, a geophysical technique (FERT, fast electrical resistivity tomography) is proposed for imaging the distribution of the salt plume used for dilution gauging at every point along a sampling cross section. With this imaging, complete mixing can be verified. If the mixing is not complete, the image created by FERT can also provide a possible guidance for selecting water-sampling locations in the sampling cross section. A water multi-sampling system prototype aimed to potentially take into account concentration variability is also proposed and tested. The results reported in the paper show that FERT provides a three-dimensional image of the dissolved salt plume and that this can potentially help in the selection of water sampling points.

  13. Field identification of stagnant zones in nested flow systems using geophysical methods

    NASA Astrophysics Data System (ADS)

    Jiang, X.; Wan, L.; Wang, J.; Yin, B.

    2013-12-01

    Periodic undulations of the water table create gravity-driven, hierarchically nested flow systems, i.e., local, intermediate and regional flow systems in drainage basins [Tóth, 1963]. The stagnant zones in nested flow systems have been assumed to be critical to accumulation of transported matter, such as metallic ions and hydrocarbons in drainage basins. However, little field research has been devoted to prove this assumption due to difficulties in groundwater sampling. In the current study, the Stratagem EH4, an electromagnetic geophysical exploration technique, is used to measure subsurface resistivity of the Cretaceous Sandstone in the Ordos Basin, Northwestern China. We obtained several two-dimensional images of variations in subsurface resistivity of cross-sections across rivers or lakes, which receive discharge from groundwater. Because the aquifer is relatively homogeneous, the spatial variation in subsurface resistivity is mainly caused by the differences in TDS of groundwater. We found that fresh groundwater with low TDS, which corresponds to local flow systems, are separated by groundwater with relatively higher TDS, which corresponds to stagnant zones caused by convergence of groundwater flow systems. This study helps shed light on the relationship between groundwater flow and distributions of hydrochemistry and also confirms that stagnant zones are loci of mineral deposition.

  14. Comparative analysis of different retrieval methods for mapping grassland leaf area index using airborne imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Atzberger, Clement; Darvishzadeh, Roshanak; Immitzer, Markus; Schlerf, Martin; Skidmore, Andrew; le Maire, Guerric

    2015-12-01

    Fine scale maps of vegetation biophysical variables are useful status indicators for monitoring and managing national parks and endangered habitats. Here, we assess in a comparative way four different retrieval methods for estimating leaf area index (LAI) in grassland: two radiative transfer model (RTM) inversion methods (one based on look-up-tables (LUT) and one based on predictive equations) and two statistical modelling methods (one partly, the other entirely based on in situ data). For prediction, spectral data were used that had been acquired over Majella National Park in Italy by the airborne hyperspectral HyMap instrument. To assess the performance of the four investigated models, the normalized root mean squared error (nRMSE) and coefficient of determination (R2) between estimates and in situ LAI measurements are reported (n = 41). Using a jackknife approach, we also quantified the accuracy and robustness of empirical models as a function of the size of the available calibration data set. The results of the study demonstrate that the LUT-based RTM inversion yields higher accuracies for LAI estimation (R2 = 0.91, nRMSE = 0.18) as compared to RTM inversions based on predictive equations (R2 = 0.79, nRMSE = 0.38). The two statistical methods yield accuracies similar to the LUT method. However, as expected, the accuracy and robustness of the statistical models decrease when the size of the calibration database is reduced to fewer samples. The results of this study are of interest for the remote sensing community developing improved inversion schemes for spaceborne hyperspectral sensors applicable to different vegetation types. The examples provided in this paper may also serve as illustrations for the drawbacks and advantages of physical and empirical models.

  15. Airborne Linear Array Image Geometric Rectification Method Based on Unequal Segmentation

    NASA Astrophysics Data System (ADS)

    Li, J. M.; Li, C. R.; Zhou, M.; Hu, J.; Yang, C. M.

    2016-06-01

    As the linear array sensor such as multispectral and hyperspectral sensor has great potential in disaster monitoring and geological survey, the quality of the image geometric rectification should be guaranteed. Different from the geometric rectification of airborne planar array images or multi linear array images, exterior orientation elements need to be determined for each scan line of single linear array images. Internal distortion persists after applying GPS/IMU data directly to geometrical rectification. Straight lines may be curving and jagged. Straight line feature -based geometrical rectification algorithm was applied to solve this problem, whereby the exterior orientation elements were fitted by piecewise polynomial and evaluated with the straight line feature as constraint. However, atmospheric turbulence during the flight is unstable, equal piecewise can hardly provide good fitting, resulting in limited precision improvement of geometric rectification or, in a worse case, the iteration cannot converge. To solve this problem, drawing on dynamic programming ideas, unequal segmentation of line feature-based geometric rectification method is developed. The angle elements fitting error is minimized to determine the optimum boundary. Then the exterior orientation elements of each segment are fitted and evaluated with the straight line feature as constraint. The result indicates that the algorithm is effective in improving the precision of geometric rectification.

  16. Airborne gamma-ray spectrometer survey data application in spatial methods

    SciTech Connect

    Bresnahan, P.J.

    1996-12-31

    The purpose of this research was to develop a methodology that used geographic information system (GIS) tools to convert airborne gamma-ray spectrometer (AGRS) survey data to various spatial data formats for use in radiological hazard mapping and risk assessments. The importance of this conversion methodology results from the versatility and consistency of spatial interpolations using commercially supported software as opposed to previous methods. Maps of interpolated AGRS data provide potential radiological hazard boundaries, delineated by user-defined limits, to guide intense field surveys. Resulting GIS products may be combined with other risk assessment inputs to model and monitor hazardous environments. The AGRS data used in this research was collected during the 1991 sitewide survey at Savannah River site (SRS) as part of the comprehensive integrated remote sensing (CIRS) program conducted by EG&G for the SRS. The AGRS survey component of the program is designed to provide a database for studying the transport of manufactured radionuclides through the environment at the SRS and surrounding areas. The AGRS data have historically been presented only in hardcopy format as acetate overlays on aerial photography. Recently, digital files representing contoured isotopic response have been delivered to the SRS as GIS themes. Since AGRS data are often a collection of dense sample points, interpolation of the data has previously been conducted by connecting points in series along flight paths. To improve on the original algorithm used to contour AGRS data, a triangulated irregular network (TIN) was used as the data model for contour and raster generation.

  17. Analysis of dolines using multiple methods applied to airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Bauer, Christian

    2015-12-01

    Delineating dolines is not a straightforward process especially in densely vegetated areas. This paper deals quantitatively with the surface karst morphology of a Miocene limestone occurrence in the Styrian Basin, Austria. The study area is an isolated karst mountain with a smooth morphology (former planation surface of Pliocene age), densely vegetated (mixed forest) and with a surface area of 1.3 km2. The study area is located near the city of Wildon and is named "Wildoner Buchkogel". The aim of this study was to test three different approaches in order to automatically delineate dolines. The data basis for this was a high resolution digital terrain model (DTM) derived from airborne laser scanning (ALS) and with a raster resolution of 1 × 1 m. The three different methods for doline boundary delineation are: (a) the "traditional" method based on the outermost closed contour line; (b) boundary extraction based on a drainage correction algorithm (filling up pits), and (c) boundary extraction based on hydrologic modelling (watershed). Extracted features are integrated in a GIS environment and analysed statistically regarding spatial distribution, shape geometry, elongation direction and volume. The three methods lead to different doline boundaries and therefore investigated parameters show significant variations. The applied methods have been compared with respect to their application purpose. Depending on delineation process, between 118 and 189 dolines could be defined. The high density of surface karst features demonstrates that solutional processes are major factors in the landscape development of the Wildoner Buchkogel. Furthermore the correlation to the landscape evolution of the Grazer Bergland is discussed.

  18. Using Methods of Dimension Reduction to Expand Data Integration and Reduce Uncertainty in Hydrological and Geophysical Parameters

    NASA Astrophysics Data System (ADS)

    Yu, A.; Savoy, H.; Heße, F.; Rubin, Y.

    2015-12-01

    The Method of Anchored Distributions (MAD), first demonstrated by Rubin et al. in 2010, has been particularly useful in hydrological and geophysical applications. MAD provides a new framework for successfully using diverse data for the characterization of heterogeneous subsurface quantities (eg. hydraulic conductivity). Through Bayesian inverse modeling, MAD is able to take a general, assumption-free approach, incorporating both local data, ie. data that pertains directly to the target quantity, as well as other indirectly related non-local data. The latter are used for the inversion and converted into local data, called 'anchors', therefore improving the overall characterization of the target variable. However, with the use of more and more data, problems arise with the inversion due to the high dimensionality of said data, eg. when using time series. As a result, MAD becomes increasingly difficult, if not impossible, to use for large data sets. The objective of our study is therefore to investigate and demonstrate effective methods of dimension reduction that reduces large data sets to a small set of relevant parameters while still retaining a strong effect on the inversion procedure. The poster will explain the relevant methods and present examples of their effect on different data types, primarily looking at hydrological data (ie. concentration breakthrough curves, drawdown time series or vertical head profiles) then further theorizing its possible application to geophysical information. Ultimately, the broader goal of this study is to propose ways of applying dimension reduction to the realm of hydrogeophysics, which will not only expand the application of MAD, but also improve our ability to reduce uncertainty in the relevant parameters.

  19. A miniature research vessel: A small-scale ocean-exploration demonstration of geophysical methods

    NASA Astrophysics Data System (ADS)

    Howell, S. M.; Boston, B.; Sleeper, J. D.; Cameron, M. E.; Togia, H.; Anderson, A.; Sigurdardottir, T. D.; Tree, J. P.

    2015-12-01

    Graduate student members of the University of Hawaii Geophysical Society have designed a small-scale model research vessel (R/V) that uses sonar to create 3D maps of a model seafloor in real-time. A pilot project was presented to the public at the School of Ocean and Earth Science and Technology's (SOEST) Biennial Open House weekend in 2013 and, with financial support from the Society of Exploration Geophysicists and National Science Foundation, was developed into a full exhibit for the same event in 2015. Nearly 8,000 people attended the two-day event, including children and teachers from Hawaii's schools, home school students, community groups, families, and science enthusiasts. Our exhibit demonstrates real-time sonar mapping of a cardboard volcano using a toy size research vessel on a programmable 2-dimensional model ship track suspended above a model seafloor. Ship waypoints were wirelessly sent from a Windows Surface tablet to a large-touchscreen PC that controlled the exhibit. Sound wave travel times were recorded using an ultrasonic emitter/receiver attached to an Arduino microcontroller platform and streamed through a USB connection to the control PC running MatLab, where a 3D model was updated as the ship collected data. Our exhibit demonstrates the practical use of complicated concepts, like wave physics, survey design, and data processing in a way that the youngest elementary students are able to understand. It provides an accessible avenue to learn about sonar mapping, and could easily be adapted to talk about bat and marine mammal echolocation by replacing the model ship and volcano. The exhibit received an overwhelmingly positive response from attendees and incited discussions that covered a broad range of earth science topics.

  20. Agricultural geophysics: Past/present accomplishments and future advancements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods have become an increasingly valuable tool for application within a variety of agroecosystems. Agricultural geophysics measurements are obtained at a wide range of scales and often exhibit significant variability both temporally and spatially. The three geophysical methods predomi...

  1. Detection of conduit-controlled ground-water flow in northwestern Puerto Rico using aerial photograph interpretation and geophysical methods

    USGS Publications Warehouse

    Rodríguez-Martínez, Jesús; Richards, Ronald T.

    2000-01-01

    The development potential of ground-water resources in the karst limestone of northwestern Puerto Rico, in an area extending from the Río Camuy to Aguadilla, is uncertain as a result of limited knowledge of the location of areas where a high density of cavities (interconnected fractures, conduits, and other dissolution features) might suggest the occurrence of high water yields. The presence in northwestern Puerto Rico of numerous coastal submarine springs, cavernous porosity in some of the wells, and rivers with entrenched and underground paths, indicate that it is probable that water-bearing, subterranean interconnected cavities occur in the area between the Río Camuy and Aguadilla. The number of exploratory wells needed to determine the location of these conduits or zones of enhanced secondary porosity could be substantially reduced if more information were available about the location of these subterranean features, greatly reducing the drilling costs associated with a trial-and-error exploratory process. A 3-year study was conducted by the U.S. Geological Survey, in cooperation with the Puerto Rico Aqueduct and Sewer Authority, to detect the presence of cavities that might suggest the occurrence of conduit-controlled groundwater flow. Aerial photographs, geologic and topographic maps, and field reconnaissance were used to identify such linear terrain features as ridges, entrenched canyons, and fracture traces. Natural potential and gravity geophysical methods were also used. The following sites were selected for the aerial photograph interpretation and geophysical testing: Caimital Bajo uplands and former Ramey Air Force Base in Aguadilla; Quebrada de los Cedros between Aguadilla and Isabela; the University of Puerto Rico Agricultural Experiment Station, Otilio dairy farm, and Pozo Brujo in Isabela; the Monte Encantado area in Moca and Isabela; and the Rio Camuy cave system in Hatillo and Camuy. In general, the degree of success varied with site and the

  2. Status of data, major results, and plans for geophysical activities, Yucca Mountain Project

    SciTech Connect

    Oliver, H.W.; Hardin, E.L.; Nelson, P.H.

    1990-07-01

    This report describes past and planned geophysical activities associated with the Yucca Mountain Project and is intended to serve as a starting point for integration of geophysical activities. This report relates past results to site characterization plans, as presented in the Yucca Mountain Site Characterization Plan (SCP). This report discusses seismic exploration, potential field methods, geoelectrical methods, teleseismic data collection and velocity structural modeling, and remote sensing. This report discusses surface-based, airborne, borehole, surface-to-borehole, crosshole, and Exploratory Shaft Facility-related activities. The data described in this paper, and the publications discussed, have been selected based on several considerations; location with respect to Yucca Mountain, whether the success or failure of geophysical data is important to future activities, elucidation of features of interest, and judgment as to the likelihood that the method will produce information that is important for site characterization. 65 refs., 19 figs., 12 tabs.

  3. Application of geophysical methods for monitoring of surface and subsurface changes of origin archaeological terrains &ndahs; case studies of sites in the Czech Republic

    NASA Astrophysics Data System (ADS)

    Křivánek, R.

    2015-08-01

    Geophysical methods could be used in wider scale for monitoring of changes of different archaeological terrains and types of archaeological situations. Agriculture, afforestation or other changes of land use play important role in real preservation of surface and subsurface and subsoil archaeological layers. Quality of many prehistoric, early medieval or medieval archaeological sites is rapidly changing during the time. Many of archaeological situations are today preserved only as subsurface remains of archaeological situations and various anthropogenic activities. A substantial part of these activities and their state of preservation can still be also traced by geophysical methods. Four examples from various types of archaeological sites in this paper document different possibilities of applied geophysical methods always dependent on state of archaeological site and conditions of measurements.

  4. Geophysical Sounding

    NASA Astrophysics Data System (ADS)

    Blake, E.

    1998-01-01

    Of the many geophysical remote-sensing techniques available today, a few are suitable for the water ice-rich, layered material expected at the north martian ice cap. Radio echo sounding has been used for several decades to determine ice thickness and internal structure. Selection of operating frequency is a tradeoff between signal attenuation (which typically increases with frequency and ice temperature) and resolution (which is proportional to wavelength). Antenna configuration and size will be additional considerations for a mission to Mars. Several configurations for ice-penetrating radar systems are discussed: these include orbiter-borne sounders, sounding antennas trailed by balloons and penetrators, and lander-borne systems. Lander-borne systems could include short-wave systems capable of resolving fine structure and layering in the upper meters beneath the lander. Spread-spectrum and deconvolution techniques can be used to increase the depth capability of a radar system. If soundings over several locations are available (e.g., with balloons, rovers, or panning short-wave systems), then it will be easier to resolve internal layering, variations in basal reflection coefficient (from which material properties may be inferred), and the geometry of nonhorizontal features. Sonic sounding has a long history in oil and gas exploration. It is, however, unlikely that large explosive charges, or even swept-frequency techniques such as Vibroseis, would be suitable for a Polar lander -- these systems are capable of penetrating several kilometers of material at frequencies of 10-200 Hz, but the energy required to generate the sound waves is large and potentially destructive. The use of audio-frequency and ultrasonic sound generated by piezoelectric crystals is discussed as a possible method to explore layering and fine features in the upper meters of the ice cap. Appropriate choice of transducer(s) will permit operation over a range of fixed or modulated frequencies

  5. A method to quantify infectious airborne pathogens at concentrations below the threshold of quantification by culture

    PubMed Central

    Cutler, Timothy D.; Wang, Chong; Hoff, Steven J.; Zimmerman, Jeffrey J.

    2013-01-01

    In aerobiology, dose-response studies are used to estimate the risk of infection to a susceptible host presented by exposure to a specific dose of an airborne pathogen. In the research setting, host- and pathogen-specific factors that affect the dose-response continuum can be accounted for by experimental design, but the requirement to precisely determine the dose of infectious pathogen to which the host was exposed is often challenging. By definition, quantification of viable airborne pathogens is based on the culture of micro-organisms, but some airborne pathogens are transmissible at concentrations below the threshold of quantification by culture. In this paper we present an approach to the calculation of exposure dose at microbiologically unquantifiable levels using an application of the “continuous-stirred tank reactor (CSTR) model” and the validation of this approach using rhodamine B dye as a surrogate for aerosolized microbial pathogens in a dynamic aerosol toroid (DAT). PMID:24082399

  6. An automated method to register airborne and terrestrial laser scanning point clouds

    NASA Astrophysics Data System (ADS)

    Yang, Bisheng; Zang, Yufu; Dong, Zhen; Huang, Ronggang

    2015-11-01

    Laser scanning techniques have been widely used to capture three-dimensional (3D) point clouds of various scenes (e.g. urban scenes). In particular, airborne laser scanning (ALS) and mobile laser scanning (MLS), terrestrial laser scanning (TLS) are effective to capture point clouds from top or side view. Registering the complimentary point clouds captured by ALS and MLS/TLS provides an aligned data source for many purposes (e.g. 3D reconstruction). Among these MLS can be directly geo-referenced to ALS according to the equipped position systems. For small scanning areas or dense building areas, TLS is used instead of MLS. However, registering ALS and TLS datasets suffers from poor automation and robustness because of few overlapping areas and sparse corresponding geometric features. A robust method for the registration of TLS and ALS datasets is proposed, which has four key steps. (1) extracts building outlines from TLS and ALS data sets independently; (2) obtains the potential matching pairs of outlines according to the geometric constraints between building outlines; (3) constructs the Laplacian matrices of the extracted building outlines to model the topology between the geometric features; (4) calculates the correlation coefficients of the extracted geometric features by decomposing the Laplacian matrices into the spectral space, providing correspondences between the extracted features for coarse registration. Finally, the multi-line adjustment strategy is employed for the fine registration. The robustness and accuracy of the proposed method are verified using field data, demonstrating a reliable and stable solution to accurately register ALS and TLS datasets.

  7. Characterisation and quantification of groundwater-surface water interactions along an alluvial stream using geophysical, hydraulic and tracer methods

    NASA Astrophysics Data System (ADS)

    Rumph Frederiksen, R.; Rasmussen, K. R.; Christensen, S.

    2015-12-01

    Qualifying and quantifying water, nutrient and contaminant exchange at the groundwater-surface water interface are becoming increasingly important for water resources management. The objectives of this study are to characterise an alluvial stream using geophysics in addition to traditional geological and geomorphological data and quantify the groundwater seepage to the stream on point-to-reach scale using both hydraulic and tracer methods. We mapped the very shallow subsurface along an alluvial stream using a GCM system (DUALEM421S, an electromagnetic system that can be operated behind a boat or towed behind a motorized vehicle) as well as using geological logs from a large number of old wells. Furthermore we made geomorphological observations through digital maps (old topographical maps and aerial photos) and field observations. We measured stream discharge (quasi-) simultaneously at several positions along the stream using both an Ott-C31 propeller instrument and an Acoustic Doppler Current Profiler instrument. The measurements were made during dry summer periods when baseflow is expected to be the dominating contribution to streamflow. Preliminary findings show that the GCM system reveals small-scale structures not seen with other data types. Furthermore, based on the GCM results and stream discharge results we have identified gaining, losing and zero exchange sections of the stream. During late summer 2015 we will collect additional hydrological data in order to support or modify our preliminary findings. To further investigate the spatial and temporal variations of the groundwater-surface water interactions along the stream we will measure groundwater seepage to the stream using: seepage meter (point-scale) DTS (reach-scale) temperature stick measurements (point-in-space-and-time-scale) temperature loggers installed in the streambed (month-scale) The measurement sites are chosen based on our geophysical, geological, and geomorphological mapping as well as our

  8. Study on pixel matching method of the multi-angle observation from airborne AMPR measurements

    NASA Astrophysics Data System (ADS)

    Hou, Weizhen; Qie, Lili; Li, Zhengqiang; Sun, Xiaobing; Hong, Jin; Chen, Xingfeng; Xu, Hua; Sun, Bin; Wang, Han

    2015-10-01

    For the along-track scanning mode, the same place along the ground track could be detected by the Advanced Multi-angular Polarized Radiometer (AMPR) with several different scanning angles from -55 to 55 degree, which provides a possible means to get the multi-angular detection for some nearby pixels. However, due to the ground sample spacing and spatial footprint of the detection, the different sizes of footprints cannot guarantee the spatial matching of some partly overlap pixels, which turn into a bottleneck for the effective use of the multi-angular detected information of AMPR to study the aerosol and surface polarized properties. Based on our definition and calculation of t he pixel coincidence rate for the multi-angular detection, an effective multi-angle observation's pixel matching method is presented to solve the spatial matching problem for airborne AMPR. Assuming the shape of AMPR's each pixel is an ellipse, and the major axis and minor axis depends on the flying attitude and each scanning angle. By the definition of coordinate system and origin of coordinate, the latitude and longitude could be transformed into the Euclidian distance, and the pixel coincidence rate of two nearby ellipses could be calculated. Via the traversal of each ground pixel, those pixels with high coincidence rate could be selected and merged, and with the further quality control of observation data, thus the ground pixels dataset with multi-angular detection could be obtained and analyzed, providing the support for the multi-angular and polarized retrieval algorithm research in t he next study.

  9. Hydrogeologic Characterization of Fractured Crystalline Bedrock on the Southern Part of Manhattan, New York, Using Advanced Borehole Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Stumm, F.; Chu, A.; Joesten, P. K.; Lane, J. W.

    2007-12-01

    ABSTRACT. Advanced borehole-geophysical methods were used to assess the hydrogeology of fractured crystalline bedrock in 31 of 64 boreholes on the southern part of Manhattan Island, N.Y. The majority of boreholes penetrated gneiss, schist, and other crystalline bedrock, and had an average depth of 591 ft (180 m) below land surface (BLS). In this study we use a combination of advanced and conventional borehole geophysical logs, and hydraulic measurements to characterize the fractured-rock ground-water flow system in southern Manhattan, N.Y. Borehole-geophysical logs collected in this study included natural gamma, single-point-resistance (SPR), short-normal resistivity (R), mechanical and acoustic caliper, magnetic susceptibility, borehole-fluid temperature and resistivity, specific conductance (SpC), dissolved oxygen (DO), pH, redox, heat-pulse flowmeter (at eight selected boreholes), borehole deviation, acoustic and optical televiewer (ATV and OTV), and directional borehole radar (at 23 selected boreholes). A new geophysical probe that collects multiple fluid parameters, included fluid- temperature, SpC, DO, pH, and redox logs; these were used to help delineate transmissive fractures in the boreholes. All boreholes penetrated moderately fractured bedrock that contained medium and large fractures. A total of 208 large fractures were delineated in the 31 boreholes logged with the OTV. Stereonet analysis of the large fractures indicates most are part of a subhorizontal population cluster with a mean orientation of N43 degrees E, 07 degrees SE and a smaller secondary population cluster dipping toward the northwest. A total of 53 faults were delineated with two major population clusters--one with a mean orientation of N12 degrees W, 66 degrees W and the other with a mean orientation of N11 degrees W, 70 degrees E. Foliation was fairly consistent throughout the study area with dip azimuths ranging from northwest to southwest and dip angles ranging from 30 to 70 degrees

  10. Retrieval of geophysical parameters from moderate resolution imaging spectroradiometer thermal infrared data: evaluation of a two-step physical algorithm.

    PubMed

    Ma, X L; Wan, Z; Moeller, C C; Menzel, W P; Gumley, L E; Zhang, Y

    2000-07-10

    A two-step physical algorithm that simultaneously retrieves geophysical parameters from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements was developed. The retrieved geophysical parameters include atmospheric temperature-humidity profile, surface skin temperature, and two surface emissivities within the shortwave (3-5-microm) and the longwave (8-14.5-microm) regions. The physical retrieval is accomplished in two steps: (i) The Tikhonov regularization method is employed to generate a regularization solution along with an optimum regularization parameter; (ii) the nonlinear Newtonian iteration algorithm is carried out with the regularization solution as a first-guess profile to obtain a final maximum probability solution for geophysical parameters. The algorithm was tested with both simulated and real MODIS Airborne Simulator (MAS) data. Sensitivity studies on simulated MAS data demonstrate that simultaneous retrievals of land and atmospheric parameters improve the accuracy of the retrieved geophysical parameters. Finally, analysis and accuracy of retrievals from real MAS data are discussed. PMID:18349925

  11. Assessment of electrical charge on airborne microorganisms by a new bioaerosol sampling method.

    PubMed

    Lee, Shu-An; Willeke, Klaus; Mainelis, Gediminas; Adhikari, Atin; Wang, Hongxia; Reponen, Tiina; Grinshpun, Sergey A

    2004-03-01

    Bioaerosol sampling is necessary to monitor and control human exposure to harmful airborne microorganisms. An important parameter affecting the collection of airborne microorganisms is the electrical charge on the microorganisms. Using a new design of an electrostatic precipitator (ESP) for bioaerosol sampling, the polarity and relative strength of the electrical charges on airborne microorganisms were determined in several laboratory and field environments by measuring the overall physical collection efficiency and the biological collection efficiency at specific precipitation voltages and polarities. First, bacteria, fungal spores, and dust dispersed from soiled carpets were sampled in a walk-in test chamber. Second, a simulant of anthrax-causing Bacillus anthracis spores was dispersed and sampled in the same chamber. Third, bacteria were sampled in a small office while four adults were engaged in lively discussions. Fourth, bacteria and fungal spores released from hay and horse manure were sampled in a horse barn during cleanup operations. Fifth, bacteria in metalworking fluid droplets were sampled in a metalworking simulator. It was found that the new ESP differentiates between positively and negatively charged microorganisms, and that in most of the tested environments the airborne microorganisms had a net negative charge. This adds a signature to the sampled microorganisms that may assist in their identification or differentiation, for example, in an anti-bioterrorism network.

  12. Comparison of different detection methods for citrus greening disease based on airborne multispectral and hyperspectral imagery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus greening or Huanglongbing (HLB) is a devastating disease spread in many citrus groves since first found in 2005 in Florida. Multispectral (MS) and hyperspectral (HS) airborne images of citrus groves in Florida were taken to detect citrus greening infected trees in 2007 and 2010. Ground truthi...

  13. Aerial remote sensing surveys, geophysical characterization. Final report

    SciTech Connect

    Labson, V.F.; Pellerin, L.; Anderson, W.L.

    1998-06-01

    The application of helicopter electromagnetic (HEM) and magnetic methods to the requirements of the environmental restoration of the Oak Ridge Reservation (ORR) demand the use of advanced, nontraditional methods of data acquisition, processing and interpretation. The cooperative study by the U.S. Geological Survey (USGS), Oak Ridge National Laboratory (ORNL), and University of California (UCB) has resulted in the planning and supervision of data acquisition, the development of tools for data processing and interpretation, and an intensive application of the methods developed. This final report consists of a series of publications which the USGS collaborated with the ORNL technical staff. These reports represent the full scope of the USGS assistance. Copies of the reports and papers are included in the Appendix. The primary goals of this effort were to quantify the effectiveness of the geophysical methods applied in the survey of the ORR for the identification of buried waste, hydrogeologic pathways by which contamination could migrate through or off the site, and for the more accurate geologic mapping of the ORR. The objectives in buried waste identification are the accurate description of the source of the geophysical anomaly and the determination of the limits of resolution of the geophysical methods to acknowledge what we might have missed. The study of hydrogeologic pathways concentrated on the identification of karst features in the limestone underlying much of the ORR. Work in this study has indicated to the ORNL staff that these karst features can be located from the airborne geophysics. The defining characteristic of this helicopter geophysical study is the collaborative nature of the effort. Each task in which the USGS was involved has included a designated staff member from the Oak Ridge National Laboratory.

  14. ON THE PHYSICS OF GALVANIC SOURCE ELECTROMAGNETIC GEOPHYSICAL METHODS FOR TERRESTRIAL AND MARINE EXPLORATION

    SciTech Connect

    David Alumbaugh and Evan Um

    2007-06-27

    A numerical study was conducted to investigate the governing physics of galvanic source electromagnetic (EM) methods for terrestrial and marine exploration scenarios. The terrestrial exploration scenario involves the grounded electric dipole source EM (GESTEM) method and the examination of how the GESTEM method can resolve a thin resistive layer representing underground gas and/or hydrocarbon storage. Numerical modeling studies demonstrate that the loop transient EM (TEM) and magnetotelluric (MT) methods are insensitive to a thin horizontal resistor at depth because they utilize horizontal currents. In contrast to these standard EM methods, the GESTEM method generates both vertical and horizontal transient currents. The vertical transient current interacts with a thin horizontal resistor and causes charge buildup on its surface. These charges produce a measurable perturbation in the surface electric field at early time. The degree of perturbation depends on source waveform. When the GESTEM method is energized with step-off waveform, the perturbation due to a thin horizontal resistor is small. This is because the step-off waveform mainly consists of low frequency signals. An alternative is taking the time-derivative of the step-off responses to approximate the impulse response which includes higher frequency signals. In order to improve degree of perturbation especially due to a localized small 3-D resistor, the diffusion angle of the vertical transient current, 45 should be considered to make vertical currents coupled to a resistive target efficiently. The major drawback of the GESTEM method lies in the fact that GESTEM sounding can not be interpreted using 1-D inversion schemes if there is near-surface inhomogeneity. The marine exploration scenario investigates the physics of marine frequency-domain controlled source EM (FDCSEM) and time-domain controlled source EM (TDCSEM) methods to explore resistive hydrocarbon reservoirs in marine environments. Unlike the

  15. Delineation of soil and groundwater contamination using geophysical methods at a waste disposal site in Canakkale, Turkey.

    PubMed

    Kaya, M Ali; Ozürlan, Gülçin; Sengül, Ebru

    2007-12-01

    Direct current (DC) resistivity, self potential (SP) and very low frequency electromagnetic (VLF-EM) measurements are carried out to detect the spread of groundwater contamination and to locate possible pathways of leachate plumes, that resulted from an open waste disposal site of Canakkale municipality. There is no proper management of the waste disposal site in which industrial and domestic wastes were improperly dumped. Furthermore, because of the dumpsite is being located at the catchment area borders of a small creek and is being topographically at a high elevation relative to the urban area, the groundwater is expected to be hazardously contaminated. Interpretations of DC resistivity geoelectrical data showed a low resistivity zone (<5 ohm-m), which appears to be a zone, that is fully saturated with leachate from an open dumpsite. The VLF-EM and SP method, support the results of geoelectrical method relating a contaminated zone in the survey area. There is a good correlation between the geophysical investigations and the results of previously collected geochemical and hydrochemical measurements.

  16. Inversion of Airborne Electromagnetic Survey Data, Styx River Area, Alaska

    NASA Astrophysics Data System (ADS)

    Kass, A.; Minsley, B. J.; Smith, B. D.; Burns, L.; Emond, A.

    2014-12-01

    A joint effort by the US Geological Survey (USGS) and the Alaska Division of Geological & Geophysical Surveys (DGGS) aims to add value to public domain airborne electromagnetic (AEM) data, collected in Alaska, through the application of newly developed advanced inversion methods to produce resistivity depth sections along flight lines. Derivative products are new geophysical data maps, interpretative profiles and displays. An important task of the new processing is to facilitate calibration or leveling between adjacent surveys flown with different systems in different years. The new approach will facilitate integration of the geophysical data in the interpretation and construction of geologic framework, resource evaluations and to geotechnical studies. Four helicopter airborne electromagnetic (AEM) surveys have been flown in the Styx River area by the DGGS; Styx River, Middle Styx, East Styx, and Farewell. The Styx River flown in 2008 and Middle Styx in flown 2013, cover an area of 2300 square kilometers. These data consist of frequency-domain DIGHEM V surveys which have been numerically processed and interpreted to yield a three-dimensional model of electrical resistivity. We describe the numerical interpretation methodology (inversion) in detail, from quality assessment to interpretation. We show two methods of inversion used in these datasets, deterministic and stochastic, and describe how we use these results to define calibration parameters and assess the quality of the datasets. We also describe the difficulties and procedures for combining datasets acquired at different times.

  17. Geltape method for measurement of work related surface contamination with cobalt containing dust: correlation between surface contamination and airborne exposure.

    PubMed Central

    Poulsen, O M; Olsen, E; Christensen, J M; Vinzent, P; Petersen, O H

    1995-01-01

    OBJECTIVES--The geltape method is a new method for optical measurement of total amount of dust on surfaces. The objectives were to study the potential applicability of this method to measurements of work related cobalt exposure during painting of plates with cobalt dye. METHODS--Consecutive series of work related geltape prints were taken from surfaces inside and outside the ventilation cabins of two plate painters during two full working days. The amount of dust picked up by the geltapes was measured optically with a field monitor. Also, personal air samples were collected on filters at the different work processes. In the laboratory the contents of cobalt on the geltape prints and the filters were measured with inductive coupled plasma atomic emission spectroscopy. RESULTS--The key results were: (a) when the geltape prints were taken from surfaces inside the cabins the optically measured area of the geltapes covered with total dust (area (%)) correlated well with the chemically measured amount of cobalt present on the geltapes. Linear correlation coefficient (R2) was 0.91 for geltape prints taken on the floor and 0.94 for prints taken on the ceiling; (b) the cumulative airborne cobalt exposure, calculated from data on work related exposure by personal sampling, correlated with the area (%) of geltape prints taken from the ceiling of the cabin (R2 = 0.98); (c) the geltape method could be used to distinguish both between work processes with different levels of cobalt exposure, and between plate painters subjected to significant differences in airborne cobalt exposure. CONCLUSION--The geltape method could produce measures of the work related exposures as well as whole day exposure for cobalt. The geltape results correlated with measurements of personal airborne cobalt exposure. In this industry the profile of exposure is well-defined in time, and it seems reasonable to apply this fast and low cost method in routine exposure surveillance to obtain a more detailed

  18. Device and method for accurately measuring concentrations of airborne transuranic isotopes

    DOEpatents

    McIsaac, C.V.; Killian, E.W.; Grafwallner, E.G.; Kynaston, R.L.; Johnson, L.O.; Randolph, P.D.

    1996-09-03

    An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector. 7 figs.

  19. Device and method for accurately measuring concentrations of airborne transuranic isotopes

    DOEpatents

    McIsaac, Charles V.; Killian, E. Wayne; Grafwallner, Ervin G.; Kynaston, Ronnie L.; Johnson, Larry O.; Randolph, Peter D.

    1996-01-01

    An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector.

  20. Application of spectral Lanczos decomposition method to large scale problems arising geophysics

    SciTech Connect

    Tamarchenko, T.

    1996-12-31

    This paper presents an application of Spectral Lanczos Decomposition Method (SLDM) to numerical modeling of electromagnetic diffusion and elastic waves propagation in inhomogeneous media. SLDM approximates an action of a matrix function as a linear combination of basis vectors in Krylov subspace. I applied the method to model electromagnetic fields in three-dimensions and elastic waves in two dimensions. The finite-difference approximation of the spatial part of differential operator reduces the initial boundary-value problem to a system of ordinary differential equations with respect to time. The solution to this system requires calculating exponential and sine/cosine functions of the stiffness matrices. Large scale numerical examples are in a good agreement with the theoretical error bounds and stability estimates given by Druskin, Knizhnerman, 1987.

  1. Study on the Integrated Geophysic Methods and Application of Advanced Geological Detection for Complicated Tunnel

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Xiao, G.

    2014-12-01

    The engineering geological and hydrological conditions of current tunnels are more and more complicated, as the tunnels are elongated with deeper depth. In constructing these complicated tunnels, geological hazards prone to occur as induced by unfavorable geological bodies, such as fault zones, karst or hydrous structures, etc. The working emphasis and difficulty of the advanced geological exploration for complicated tunnels are mainly focused on the structure and water content of these unfavorable geological bodies. The technical aspects of my paper systematically studied the advanced geological exploration theory and application aspects for complicated tunnels, with discussion on the key technical points and useful conclusions. For the all-aroundness and accuracy of advanced geological exploration results, the objective of my paper is targeted on the comprehensive examination on the structure and hydrous characteristic of the unfavorable geological bodies in complicated tunnels. By the multi-component seismic modeling on a more real model containing the air medium, the wave field response characteristics of unfavorable geological bodies can be analyzed, thus providing theoretical foundation for the observation system layout, signal processing and interpretation of seismic methods. Based on the tomographic imaging theory of seismic and electromagnetic method, 2D integrated seismic and electromagnetic tomographic imaging and visualization software was designed and applied in the advanced drilling hole in the tunnel face, after validation of the forward and inverse modeling results on theoretical models. The transmission wave imaging technology introduced in my paper can be served as a new criterion for detection of unfavorable geological bodies. After careful study on the basic theory, data processing and interpretation, practical applications of TSP and ground penetrating radar (GPR) method, as well as serious examination on their application examples, my paper

  2. A comparison of four geophysical methods for determining the shear wave velocity of soils

    USGS Publications Warehouse

    Anderson, N.; Thitimakorn, T.; Ismail, A.; Hoffman, D.

    2007-01-01

    The Missouri Department of Transportation (MoDOT) routinely acquires seismic cone penetrometer (SCPT) shear wave velocity control as part of the routine investigation of soils within the Mississippi Embayment. In an effort to ensure their geotechnical investigations are as effective and efficient as possible, the SCPT tool and several available alternatives (crosshole [CH]; multichannel analysis of surface waves [MASW]; and refraction microtremor [ReMi]) were evaluated and compared on the basis of field data acquired at two test sites in southeast Missouri. These four methods were ranked in terms of accuracy, functionality, cost, other considerations, and overall utility. It is concluded that MASW data are generally more reliable than SCPT data, comparable to quality ReMi data, and only slightly less accurate than CH data. However, the other advantages of MASW generally make it a superior choice over the CH, SCPT, and ReMi methods for general soil classification purposes to depths of 30 m. MASW data are less expensive than CH data and SCPT data and can normally be acquired in areas inaccessible to drill and SCPT rigs. In contrast to the MASW tool, quality ReMi data can be acquired only in areas where there are interpretable levels of "passive" acoustic energy and only when the geophone array is aligned with the source(s) of such energy.

  3. Finding a needle by removing the haystack: A spatio-temporal normalization method for geophysical data

    NASA Astrophysics Data System (ADS)

    Pavlidou, E.; van der Meijde, M.; van der Werff, H.; Hecker, C.

    2016-05-01

    We introduce a normalization algorithm which highlights short-term, localized, non-periodic fluctuations in hyper-temporal satellite data by dividing each pixel by the mean value of its spatial neighbourhood set. In this way we suppress signal patterns that are common in the central and surrounding pixels, utilizing both spatial and temporal information at different scales. We test the method on two subsets of a hyper-temporal thermal infra-red (TIR) dataset. Both subsets are acquired from the SEVIRI instrument onboard the Meteosat-9 geostationary satellite; they cover areas with different spatiotemporal TIR variability. We impose artificial fluctuations on the original data and apply a window-based technique to retrieve them from the normalized time series. We show that localized short-term fluctuations as low as 2 K, which were obscured by large-scale variable patterns, can be retrieved in the normalized time series. Sensitivity of retrieval is determined by the intrinsic variability of the normalized TIR signal and by the amount of missing values in the dataset. Finally, we compare our approach with widely used techniques of statistical and spectral analysis and we discuss the improvements introduced by our method.

  4. Geophysical methods as mapping tools in a strata-bound gold deposit: Haile mine, South Carolina slate belt.

    USGS Publications Warehouse

    Wynn, J.C.; Luce, R.W.

    1984-01-01

    The Haile mine is the largest gold producer in the eastern USA. It is postulated to be a strata-bound gold deposit formed by a fumarolic or hot-spring system in felsic tuffs of Cambrian(?) age. Two mineralized zones occur, each composed of a sericitic part overlain by a siliceous part. Au is concentrated in especially silicified horizons and in pyrite horizons in the siliceous part of each mineralized zone. The tuffs are metamorphosed to greenschist facies and intruded by diabase and other mafic dykes. Weathering is deep and the mineralized tuffs are partly covered by coastal-plain sediments. It is suggested that certain geophysical methods may be useful in mapping and exploring Haile-type deposits in the Carolina slate belt. Very low frequency electromagnetic resistivity surveys help define alteration and silicified zones. A magnetic survey found sharp highs that correlate with unexposed mafic and ultramafic dykes. Induced polarization proved useful in giving a two-dimensional view of the structure.-G.J.N.

  5. Recent surface temperature trends in the interior of East Antarctica from borehole firn temperature measurements and geophysical inverse methods

    USGS Publications Warehouse

    Muto, A.; Scambos, T.A.; Steffen, K.; Slater, A.G.; Clow, G.D.

    2011-01-01

    We use measured firn temperatures down to depths of 80 to 90 m at four locations in the interior of Dronning Maud Land, East Antarctica to derive surface temperature histories spanning the past few decades using two different inverse methods. We find that the mean surface temperatures near the ice divide (the highest-elevation ridge of East Antarctic Ice Sheet) have increased approximately 1 to 1.5 K within the past ???50 years, although the onset and rate of this warming vary by site. Histories at two locations, NUS07-5 (78.65S, 35.64E) and NUS07-7 (82.07S, 54.89E), suggest that the majority of this warming took place in the past one or two decades. Slight cooling to no change was indicated at one location, NUS08-5 (82.63S, 17.87E), off the divide near the Recovery Lakes region. In the most recent decade, inversion results indicate both cooler and warmer periods at different sites due to high interannual variability and relatively high resolution of the inverted surface temperature histories. The overall results of our analysis fit a pattern of recent climate trends emerging from several sources of the Antarctic temperature reconstructions: there is a contrast in surface temperature trends possibly related to altitude in this part of East Antarctica. Copyright 2011 by the American Geophysical Union.

  6. Geophex airborne unmanned survey system

    SciTech Connect

    Won, I.J.; Taylor, D.W.A.

    1995-03-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This nonintrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits two operators to rapidly conduct geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance, of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak anomalies can be detected.

  7. Flowmeter and Ground Penetrating Radar: comparison between hydrogeological and geophysical methods

    NASA Astrophysics Data System (ADS)

    Villa, A.; Basirico', S.; Arato, A.; Crosta, G. B.; Frattini, P.; Godio, A.

    2012-04-01

    A comparison between saturated hydraulic conductivity calculated with Electromagnetic Borehole Flowmeter (EBF) and water content obtained by Ground Penetrating Radar (GPR) Zero Offset Profile (ZOP) is presented. EBF technique permits to obtain permeability profiles along one borehole in the saturated zone by using the Moltz (1993) method. The analysis of ZOP data provides information about the water content (Topp, 1980) in the section between two adjacent boreholes. Water content profiles in the saturated zone can be related to the porosity of the medium which, together with the permeability from EBF measurements, is fundamental for any hydrogeological characterization. These two methods have been applied to three different test-sites located in the Northern Italy. A first site regards a complex aquifer, characterized by a chaotic sequence of gypsum-marls. The other two sites are characterized by an alternation of sandy and silty-sandy layers. For each site, we adopted the EBF along screened boreholes with 0.25 m spacing, under ambient and stressed conditions. The cross-hole georadar survey was performed within the saturated zone by using 100 Hz borehole antennas with 0.25 m spacing. The results from the analysis of EBF and ZOP profiles show a general positive correlation between permeability and water content and porosity. This is reasonable for granular soils where the permeability is controlled by the pore space available for water flow, i.e., the effective porosity. For this soils, where EBF permeability and ZOP water-content profiles are in good agreement, the volume between the boreholes can be supposed to be homogeneous. On the other hand, a poor correlation suggests the presence of heterogeneity between the boreholes, which can be observed because the two techniques involve different volumes of soil: the EBF permeability refers to a portion of volume just around the borehole while the ZOP investigates the entire volume between the two boreholes. The poor

  8. Borehole geophysical methods for analyzing specific capacity of multiaquifer wells : ground-water hydraulics

    USGS Publications Warehouse

    Bennett, Gordon D.; Patten, Eugene P., Jr.

    1960-01-01

    Conventional well-logging techniques, combined with measurements of flow velocity in the borehole, can provide information on the discharge-drawdown characteriBtic8 of the several aquifers penetrated by a well. The information is most conveniently presented in a graph showing aquifer discharges as functions of the water level in the well at a particular time. To determine the discharge-drawdown characteristics, a well is pumped at a steady rate for a certain length of time. While the well is being pumped, measurements are made of drawdown and of the discharge rates of the individual aquifers within the well. Discharge rates and drawdowns ,are usually recorded as functions of time, and their values for any given time during the test are obtained by interpolation. The procedure is repeated for several different rates of total well discharge. The well may be allowed to recover after each step, or discharge may be changed from one rate to another, and changes in discharge and drawdown may be measured by extrapolation. The flow measurements within the well may be made by use of a subsurface flowmeter or by one of several techniques involving the injection of electrolytic or radioactive tracers. The method was tested on a well in Mercer County, Pa., and provided much useful information on aquifer yields, 'thieving,' and hydrostatic heads of the individual zones.

  9. A Novel Azimuth Super-Resolution Method by Synthesizing Azimuth Bandwidth of Multiple Tracks of Airborne Stripmap SAR Data.

    PubMed

    Wang, Yan; Li, Jingwen; Sun, Bing; Yang, Jian

    2016-06-13

    Azimuth resolution of airborne stripmap synthetic aperture radar (SAR) is restricted by the azimuth antenna size. Conventionally, a higher azimuth resolution should be achieved by employing alternate modes that steer the beam in azimuth to enlarge the synthetic antenna aperture. However, if a data set of a certain region, consisting of multiple tracks of airborne stripmap SAR data, is available, the azimuth resolution of specific small region of interest (ROI) can be conveniently improved by a novel azimuth super-resolution method as introduced by this paper. The proposed azimuth super-resolution method synthesize the azimuth bandwidth of the data selected from multiple discontinuous tracks and contributes to a magnifier-like function with which the ROI can be further zoomed in with a higher azimuth resolution than that of the original stripmap images. Detailed derivation of the azimuth super-resolution method, including the steps of two-dimensional dechirping, residual video phase (RVP) removal, data stitching and data correction, is provided. The restrictions of the proposed method are also discussed. Lastly, the presented approach is evaluated via both the single- and multi-target computer simulations.

  10. A Novel Azimuth Super-Resolution Method by Synthesizing Azimuth Bandwidth of Multiple Tracks of Airborne Stripmap SAR Data.

    PubMed

    Wang, Yan; Li, Jingwen; Sun, Bing; Yang, Jian

    2016-01-01

    Azimuth resolution of airborne stripmap synthetic aperture radar (SAR) is restricted by the azimuth antenna size. Conventionally, a higher azimuth resolution should be achieved by employing alternate modes that steer the beam in azimuth to enlarge the synthetic antenna aperture. However, if a data set of a certain region, consisting of multiple tracks of airborne stripmap SAR data, is available, the azimuth resolution of specific small region of interest (ROI) can be conveniently improved by a novel azimuth super-resolution method as introduced by this paper. The proposed azimuth super-resolution method synthesize the azimuth bandwidth of the data selected from multiple discontinuous tracks and contributes to a magnifier-like function with which the ROI can be further zoomed in with a higher azimuth resolution than that of the original stripmap images. Detailed derivation of the azimuth super-resolution method, including the steps of two-dimensional dechirping, residual video phase (RVP) removal, data stitching and data correction, is provided. The restrictions of the proposed method are also discussed. Lastly, the presented approach is evaluated via both the single- and multi-target computer simulations. PMID:27304959

  11. A Novel Azimuth Super-Resolution Method by Synthesizing Azimuth Bandwidth of Multiple Tracks of Airborne Stripmap SAR Data

    PubMed Central

    Wang, Yan; Li, Jingwen; Sun, Bing; Yang, Jian

    2016-01-01

    Azimuth resolution of airborne stripmap synthetic aperture radar (SAR) is restricted by the azimuth antenna size. Conventionally, a higher azimuth resolution should be achieved by employing alternate modes that steer the beam in azimuth to enlarge the synthetic antenna aperture. However, if a data set of a certain region, consisting of multiple tracks of airborne stripmap SAR data, is available, the azimuth resolution of specific small region of interest (ROI) can be conveniently improved by a novel azimuth super-resolution method as introduced by this paper. The proposed azimuth super-resolution method synthesize the azimuth bandwidth of the data selected from multiple discontinuous tracks and contributes to a magnifier-like function with which the ROI can be further zoomed in with a higher azimuth resolution than that of the original stripmap images. Detailed derivation of the azimuth super-resolution method, including the steps of two-dimensional dechirping, residual video phase (RVP) removal, data stitching and data correction, is provided. The restrictions of the proposed method are also discussed. Lastly, the presented approach is evaluated via both the single- and multi-target computer simulations. PMID:27304959

  12. Investigation of the Sultan Alp Arslan tomb with geophysical methods, in the historical Merv city (Turkestan)

    NASA Astrophysics Data System (ADS)

    Kadioglu, Selma; Kagan Kadioglu, Yusuf

    2016-04-01

    Sultan Alp Arslan (1029-1072) was the second Sultan of the Seljuq Empire and great-grandson of Seljuq the eponymous founder of the dynasty. Sultan Alp Arslan's victories changed the balance in near Asia completely in favour of the Seljuq Turks and Sunni Muslims. His victory at Manzikert (26 August 1071) is often cited as the beginning of the end of Byzantine power in Anatolia, and the beginning of Turkish identity in Anatolia. Sultan Alp Arslan eliminated theobstacles to the conquest of Anatolia and played a major role in making this territory a homeland for the Seljuqs. By taking the Emperor captive, Sultan Alp Arslan gained great fame but in 1072, on an expedition to Western Turkestan, he met with death in an unexpected way and at a relatively early age, in his 42nd year. There have been found different stories of the death of this great Turkish Sultan in certain sources. Unfortunately, there has not been found The Sultan's resting place until now. This paper is concerned with the investigation of the Sultan Alp Arslan Tomb in the historical Merv (Marv) city in Turkestan, by using Ground Penetrating Radar (GPR) and gradiometer methods. The GPR and gradiometer surveys have been realized in Gavur Fortress, Sultan Fortress, Er Fortress districts and between two big Fortresses in old Merv city in selected nine study areas. We also gathered data in and around Sultan Sancar Tomb. GPR surveys were performed during January 2014 employing Ramac CU-II system equipped with a 250 MHz shielded antenna, on one meter spaced profiles. Similarly a Geoscan system was used to take magnetic data. The results of all these investigation revealed that there were possible traces for the buried tomb of the Sultan Alparslan in Gavur Kale around Cuma Mosque and around Sultan Sancar Tomb in the study region. However, the project team was changed after our study, and the new team did not excavated our determined areas. Acknowledgement This project has been supported by Republic of Turkey

  13. Geochemical Characterization Using Geophysical Data and Markov Chain Monte Carolo methods: A Case Study at the South Oyster Bacterial Transport Site in Virginia

    SciTech Connect

    Chen, Jinsong; Hubbard, Susan; Rubin, Yoram; Murray, Chris; Roden, Eric; Majer, Ernest

    2003-11-18

    The spatial distribution of field-scale geochemical parameters, such as extractable Fe(II) and Fe(III), influences microbial processes and thus the efficacy of bioremediation. Because traditional characterization of those parameters is invasive and laborious, it is rarely performed sufficiently at the field-scale. Since both geochemical and geophysical parameters often correlate to some common physical properties (such as lithofacies), we investigated the utility of tomographic radar attenuation data for improving estimation of geochemical parameters using a Markov Chain Monte Carlo (MCMC) approach. The data used in this study included physical, geophysical, and geochemical measurements collected in and between several boreholes at the DOE South Oyster Bacterial Transport Site in Virginia. Results show that geophysical data, constrained by physical data, provided field-scale information about extractable Fe(II) and Fe(III) in a minimally invasive manner and with a resolution unparalleled by other geochemical characterization methods. This study presents our estimation framework for estimating Fe(II) and Fe(III), and its application to a specific site. Our hypothesis--that geochemical parameters and geophysical attributes can be linked through their mutual dependence on physical properties--should be applicable for estimating other geochemical parameters at other sites.

  14. Review of airborne emissions from agricultural fumigants: design and uncertainty considerations for the use of the integrated horizontal flux method.

    PubMed

    Sullivan, D A; Ajwa, H A

    2011-01-01

    Ground-level area sources, such as those associated with the use of agricultural fumigants, waste disposal sites, wastewater lagoons, and other applications, present a challenge in terms of characterizing atmospheric flux as a function of time. Studies are costly in terms of field activities and laboratory analysis. The optimization of field study design, therefore, is essential to conduct cost-effective research. The collection of on-field profile data for airborne concentration, wind speed, and wind direction can be used in conjunction with the integrated horizontal flux (IHF) method to empirically compute complex source terms as a function of time. This paper focuses on complicating factors and field study design issues for the use of the IHF method. Insights and examples are drawn from five field research studies. The methods and results of characterizing the uncertainty and method precision in the emission fitting for the IHF method also are presented.

  15. Direct Analysis of Low-Volatile Molecular Marker Extract from Airborne Particulate Matter Using Sensitivity Correction Method

    PubMed Central

    Irei, Satoshi

    2016-01-01

    Molecular marker analysis of environmental samples often requires time consuming preseparation steps. Here, analysis of low-volatile nonpolar molecular markers (5-6 ring polycyclic aromatic hydrocarbons or PAHs, hopanoids, and n-alkanes) without the preseparation procedure is presented. Analysis of artificial sample extracts was directly conducted by gas chromatography-mass spectrometry (GC-MS). After every sample injection, a standard mixture was also analyzed to make a correction on the variation of instrumental sensitivity caused by the unfavorable matrix contained in the extract. The method was further validated for the PAHs using the NIST standard reference materials (SRMs) and then applied to airborne particulate matter samples. Tests with the SRMs showed that overall our methodology was validated with the uncertainty of ~30%. The measurement results of airborne particulate matter (PM) filter samples showed a strong correlation between the PAHs, implying the contributions from the same emission source. Analysis of size-segregated PM filter samples showed that their size distributions were found to be in the PM smaller than 0.4 μm aerodynamic diameter. The observations were consistent with our expectation of their possible sources. Thus, the method was found to be useful for molecular marker studies. PMID:27127511

  16. A Multispectral Image Creating Method for a New Airborne Four-Camera System with Different Bandpass Filters

    PubMed Central

    Li, Hanlun; Zhang, Aiwu; Hu, Shaoxing

    2015-01-01

    This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and the scale-invariant feature transform (SIFT) and random sample consensus (RANSAC) were used to generate matching points. For the difficult registration problem between visible band images and near-infrared band images in cases lacking manmade objects, we presented an effective method based on the structural characteristics of the system. Experiments show that our method can acquire high quality multispectral images and the band-to-band alignment error of the composed multiple spectral images is less than 2.5 pixels. PMID:26205264

  17. Assessment of offshore New Jersey sources of Beach replenishment sand by diversified application of geologic and geophysical methods

    USGS Publications Warehouse

    Waldner, J.S.; Hall, D.W.; Uptegrove, J.; Sheridan, R.E.; Ashley, G.M.; Esker, D.

    1999-01-01

    . The seismograms are then correlated to the digital seismic profile to confirm reflected events. They are particularly useful where individual reflection events cannot be detected but a waveform generated by several thin lithologic units can be recognized. Progress in application of geologic and geophysical methods provides advantages in detailed sediment analysis and volumetric estimation of offshore sand ridges. New techniques for current and ongoing beach replenishment projects not only expand our knowledge of the geologic processes involved in sand ridge origin and development, but also improve our assessment of these valuable resources. These reconnaissance studies provide extensive data to the engineer regarding the suitability and quantity of sand and can optimize placement and analysis of vibracore samples.Beach replenishment serves the dual purpose of maintaining a source of tourism and recreation while protecting life and property. Research has improved both data collection and interpretation of seismic surveys and vibracore analysis for projects investigating sand ridges offshore of New Jersey. The New Jersey Geological Survey in cooperation with Rutgers University is evaluating the capabilities of digital seismic data to analyze sand ridges. The printing density of analog systems limits the dynamic range to about 24 dB. Digital acquisition systems with dynamic ranges about 100 dB can permit enhanced seismic profiles by trace static correction, deconvolution, automatic gain scaling, horizontal stacking and digital filtering.

  18. Individual tree crown delineation using localized contour tree method and airborne LiDAR data in coniferous forests

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Yu, Bailang; Wu, Qiusheng; Huang, Yan; Chen, Zuoqi; Wu, Jianping

    2016-10-01

    Individual tree crown delineation is of great importance for forest inventory and management. The increasing availability of high-resolution airborne light detection and ranging (LiDAR) data makes it possible to delineate the crown structure of individual trees and deduce their geometric properties with high accuracy. In this study, we developed an automated segmentation method that is able to fully utilize high-resolution LiDAR data for detecting, extracting, and characterizing individual tree crowns with a multitude of geometric and topological properties. The proposed approach captures topological structure of forest and quantifies topological relationships of tree crowns by using a graph theory-based localized contour tree method, and finally segments individual tree crowns by analogy of recognizing hills from a topographic map. This approach consists of five key technical components: (1) derivation of canopy height model from airborne LiDAR data; (2) generation of contours based on the canopy height model; (3) extraction of hierarchical structures of tree crowns using the localized contour tree method; (4) delineation of individual tree crowns by segmenting hierarchical crown structure; and (5) calculation of geometric and topological properties of individual trees. We applied our new method to the Medicine Bow National Forest in the southwest of Laramie, Wyoming and the HJ Andrews Experimental Forest in the central portion of the Cascade Range of Oregon, U.S. The results reveal that the overall accuracy of individual tree crown delineation for the two study areas achieved 94.21% and 75.07%, respectively. Our method holds great potential for segmenting individual tree crowns under various forest conditions. Furthermore, the geometric and topological attributes derived from our method provide comprehensive and essential information for forest management.

  19. Sustainable urban development and geophysics

    NASA Astrophysics Data System (ADS)

    Liu, Lanbo; Chan, L. S.

    2007-09-01

    investigated [2]. The first objective of urban geophysics is to study systematically the geophysical fields in cities, searching for principles and processes governing the intensity and patterns of variation of the geophysical properties, as well as the potential consequences on the biosphere. Secondly, geophysics has already been found to be a useful tool for subsurface detection and investigation, hazard mitigation, and assessment of environmental contamination. Geophysicists have documented numerous cases of successful applications of geophysical techniques to solve problems related to hazard mitigation, safeguarding of lifeline infrastructure and urban gateways (air- and sea-ports, railway and highway terminals), archaeological and heritage surveys, homeland security, urban noise control, water supplies, sanitation and solid waste management etc. In contrast to conventional geophysical exploration, the undertaking of geophysical surveys in an urban setting faces many new challenges and difficulties. First of all, the ambient cultural noise in cities caused by traffic, electromagnetic radiation and electrical currents often produce undesirably strong interference with geophysical measurements. Secondly, subsurface surveys in an urban area are often targeted at the uppermost several metres of the ground, which are the most heterogeneous layers with many man-made objects. Thirdly, unlike conventional geophysical exploration which requires resolution in the order of metres, many urban geophysical surveys demand a resolution and precision in the order of centimetres or even millimetres. Finally restricted site access and limited time for conducting geophysical surveys, regulatory constraints, requirements for traffic management and special logistical arrangements impose additional difficulties. All of these factors point to the need for developing innovative research methods and geophysical instruments suitable for use in urban settings. This special issue on 'Sustainable urban

  20. Investigation of the potential for concealed base-metal mineralization at the Drenchwater Creek Zn-Pb-Ag occurrence, northern Alaska, using geology, reconnaissance geochemistry, and airborne electromagnetic geophysics

    USGS Publications Warehouse

    Graham, Garth E.; Deszcz-Pan, Maria; Abraham, Jared; Kelley, Karen D.

    2011-01-01

    No drilling has taken place at the Drenchwater occurrence, so alternative data sources (for example, geophysics) are especially important in assessing possible indicators of mineralization. Data from the 2005 electromagnetic survey define the geophysical character of the rocks at Drenchwater and, in combination with geological and surface-geochemical data, can aid in assessing the possible shallow (up to about 50 m), subsurface lateral extent of base-metal sulfide accumulations at Drenchwater. A distinct >3-km-long electromagnetic conductive zone (observed in apparent resistivity maps) coincides with, and extends further westward than, mineralized shale outcrops and soils anomalously high in Pb concentrations within the Kuna Formation; this conductive zone may indicate sulfide-rich rock. Models of electrical resistivity with depth, generated from inversion of electromagnetic data, which provide alongflight-line conductivity-depth profiles to between 25 and 50 m below ground surface, show that the shallow subsurface conductive zone occurs in areas of known mineralized outcrops and thins to the east. Broader, more conductive rock along the western ~1 km of the geophysical anomaly does not reach ground surface. These data suggest that the Drenchwater deposit is more extensive than previously thought. The application of inversion modeling also was applied to another smaller geochemical anomaly in the Twistem Creek area. The results are inconclusive, but they suggest that there may be a local conductive zone, possibly due to sulfides.

  1. Environmental and Engineering Geophysical University at SAGEEP 2008: Geophysical Instruction for Non-Geophysicists

    SciTech Connect

    Jeffrey G. Paine

    2009-03-13

    The Environmental and Engineering Geophysical Society (EEGS), a nonprofit professional organization, conducted an educational series of seminars at the Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP) in Philadelphia in April 2008. The purpose of these seminars, conducted under the name Environmental and Engineering Geophysical University (EEGU) over three days in parallel with the regular SAGEEP technical sessions, was to introduce nontraditional geophysical conference attendees to the appropriate use of geophysics in environmental and engineering projects. Five half-day, classroom-style sessions were led by recognized experts in the application of seismic, electrical, gravity, magnetics, and ground-penetrating radar methods. Classroom sessions were intended to educate regulators, environmental program managers, consultants, and students who are new to near-surface geophysics or are interested in learning how to incorporate appropriate geophysical approaches into characterization or remediation programs or evaluate the suitability of geophysical methods for general classes of environmental or engineering problems.

  2. Digital data from the Great Sand Dunes airborne gravity gradient survey, south-central Colorado

    USGS Publications Warehouse

    Drenth, B.J.; Abraham, J.D.; Grauch, V.J.S.; Labson, V.F.; Hodges, G.

    2013-01-01

    This report contains digital data and supporting explanatory files describing data types, data formats, and survey procedures for a high-resolution airborne gravity gradient (AGG) survey at Great Sand Dunes National Park, Alamosa and Saguache Counties, south-central Colorado. In the San Luis Valley, the Great Sand Dunes survey covers a large part of Great Sand Dunes National Park and Preserve. The data described were collected from a high-resolution AGG survey flown in February 2012, by Fugro Airborne Surveys Corp., on contract to the U.S. Geological Survey. Scientific objectives of the AGG survey are to investigate the subsurface structural framework that may influence groundwater hydrology and seismic hazards, and to investigate AGG methods and resolution using different flight specifications. Funding was provided by an airborne geophysics training program of the U.S. Department of Defense's Task Force for Business & Stability Operations.

  3. Airborne Transparencies.

    ERIC Educational Resources Information Center

    Horne, Lois Thommason

    1984-01-01

    Starting from a science project on flight, art students discussed and investigated various means of moving in space. Then they made acetate illustrations which could be used as transparencies. The projection phenomenon made the illustrations look airborne. (CS)

  4. Application of multiple geophysical methods to hydrologic and environmental investigations at US Marine Corps installations in North Carolina

    SciTech Connect

    Cardinell, A.P.; Daniel, C.C. III

    1997-10-01

    Hydrologic information for ongoing environmental studies at two U.S. Marine Corps Bases in the Coastal Plain Province of North Carolina was obtained by using a combination of high-resolution land seismic reflection, continuous marine seismic profiling, and borehole geophysics, that included vertical seismic profiling. The geometry of areas of missing confining units at the southern end of Cherry Point Marine Corps Air Station was mapped by using land seismic-reflection compressional (P) waves, marine seismic profiling, and borehole-geophysical and lithologic data from more than 100 water-supply and monitoring wells. The hydrogeologic framework at Camp Lejeune was mapped by using 100 miles of continuous single-channel, marine seismic-profiling data that were correlated with land-based borehole geophysical and lithologic data from 180 water-supply, monitoring, and stratigraphic test wells. These data are being used by both Marine Corps Bases to manage drinking-water supplies and plan investigations of hazardous-waste sites.

  5. Geohydrologic assessment of fractured crystalline bedrock on the southern part of Manhattan, New York, through the use of advanced borehole geophysical methods

    USGS Publications Warehouse

    Stumm, F.; Chu, A.; Joesten, P.K.; Lane, J.W.

    2007-01-01

    Advanced borehole-geophysical methods were used to assess the geohydrology of fractured crystalline bedrock in 31 of 64 boreholes on the southern part of Manhattan Island, NY in preparation of the construction of a new water tunnel. The study area is located in a highly urbanized part of New York City. The boreholes penetrated gneiss, schist, and other crystalline bedrock that has an overall southwest-to northwest-dipping foliation. Most of the fractures intersected are nearly horizontal or have moderate- to high-angle northwest or eastward dip azimuths. Heat-pulse flowmeter logs obtained under nonpumping (ambient) and pumping conditions, together with other geophysical logs, delineated transmissive fracture zones in each borehole. Water-level and flowmeter data suggest the fractured-rock ground-water-flow system is interconnected. The 60 MHz directional borehole-radar logs delineated the location and orientation of several radar reflectors that did not intersect the projection of the borehole. A total of 53 faults intersected by the boreholes have mean orientation populations of N12??W, 66??W and N11??W, 70??E. A total of 77 transmissive fractures delineated using the heat-pulse flowmeter have mean orientations of N11??E, 14??SE (majority) and N23??E, 57??NW (minority). The transmissivity of the bedrock boreholes ranged from 0.7 to 870 feet squared (ft2) per day (0.07 to 81 metres squared (m2) per day). ?? 2007 Nanjing Institute of Geophysical Prospecting.

  6. Asteroid Surface Geophysics

    NASA Astrophysics Data System (ADS)

    Murdoch, N.; Sánchez, P.; Schwartz, S. R.; Miyamoto, H.

    The regolith-covered surfaces of asteroids preserve records of geophysical processes that have occurred both at their surfaces and sometimes also in their interiors. As a result of the unique microgravity environment that these bodies possess, a complex and varied geophysics has given birth to fascinating features that we are just now beginning to understand. The processes that formed such features were first hypothesized through detailed spacecraft observations and have been further studied using theoretical, numerical, and experimental methods that often combine several scientific disciplines. These multiple approaches are now merging toward a further understanding of the geophysical states of the surfaces of asteroids. In this chapter we provide a concise summary of what the scientific community has learned so far about the surfaces of these small planetary bodies and the processes that have shaped them. We also discuss the state of the art in terms of experimental techniques and numerical simulations that are currently being used to investigate regolith processes occurring on small-body surfaces and that are contributing to the interpretation of observations and the design of future space missions.

  7. Apparatus and methods for monitoring the concentrations of hazardous airborne substances, especially lead

    DOEpatents

    Zaromb, Solomon

    2004-07-13

    Air is sampled at a rate in excess of 100 L/min, preferably at 200-300 L/min, so as to collect therefrom a substantial fraction, i.e., at least 20%, preferably 60-100%, of airborne particulates. A substance of interest (analyte), such as lead, is rapidly solubilized from the the collected particulates into a sample of liquid extractant, and the concentration of the analyte in the extractant sample is determined. The high-rate air sampling and particulate collection may be effected with a high-throughput filter cartridge or with a recently developed portable high-throughput liquid-absorption air sampler. Rapid solubilization of lead is achieved by a liquid extractant comprising 0.1-1 M of acetic acid or acetate, preferably at a pH of 5 or less and preferably with inclusion of 1-10% of hydrogen peroxide. Rapid determination of the lead content in the liquid extractant may be effected with a colorimetric or an electroanalytical analyzer.

  8. COLLECTION OF AIRBORNE PARTICLES BY A HIGH-GRADIENT PERMANENT MAGNETIC METHOD

    SciTech Connect

    Cheng, Mengdawn; Allman, Steve L; Ludtka, Gerard Michael; Avens, Larry R

    2014-01-01

    We report on the use of magnetic force in collection of airborne particles by a high- gradient permanent magnetic separation (HGPMS) device. Three aerosol particles of different magnetic susceptibility (NaCl, CuO, and Fe2O3) were generated in the electrical mobility size range of 10 to 200 nm and were used to study HGPMS collection. One HGPMS matrix element, made of stainless steel wool, was used in the device configuration. Three flow rates were selected to simulate the environmental wind speeds of interest to the study. Magnetic force was found to exhibit an insignificant effect on the separation of NaCl particles, even in the HGPMS configuration. Diffusion was a major mechanism in the removal of the diamagnetic particles; however, diffusion is insignificant under the influence of a high-gradient magnetic field for paramagnetic or ferromagnetic particles. The HGPMS showed high-performance collection (> 99%) of paramagnetic CuO and ferromagnetic Fe2O3 particles for particle sizes greater than or equal to 60 nm. As the wind speed increases, the influence of the magnetic force weakens, and the capability to remove particles from the gas stream diminishes. The results suggest that the HGPMS principle could be explored for development of an advanced miniaturized passive aerosol collector.

  9. Coupled thermo-geophysical inversion for high-latitude permafrost monitoring - assessment of the method and practical considerations

    NASA Astrophysics Data System (ADS)

    Tomaskovicova, Sonia; Paamand, Eskild; Ingeman-Nielsen, Thomas; Bauer-Gottwein, Peter

    2013-04-01

    difference between the synthetic and the measured apparent resistivities is minimized in a least-squares inversion procedure by adjusting the thermal parameters of the heat model. A site-specific calibration is required since the relation between unfrozen water content and temperature is strongly dependent on the grain size of the soil. We present details of an automated permanent field measurement setup that has been established to collect the calibration data in Ilulissat, West Greenland. Considering the station location in high latitude environment, this setup is unique of its kind since the installation of automated geophysical stations in the Arctic conditions is a challenging task. The main issues are related to availability of adapted equipment, high demand on robustness of the equipment and method due to the harsh environment, remoteness of the field sites and related powering issues of such systems. By showing the results from the new-established geoelectrical station over the freezing period in autumn 2012, we prove the 2D time lapse resistivity tomography to be an effective method for permafrost monitoring in high latitudes. We demonstrate the effectivity of time lapse geoelectrical signal for petrophysical relationship calibration, which is enhanced comparing to sparse measurements.

  10. Revealing the hidden structures of an historical bridge by high resolution geophysical methods : A case study of Pont de Coq, France

    NASA Astrophysics Data System (ADS)

    Antoine, R.; Fauchard, C.

    2012-04-01

    In the last decades, public institutions have shown an increased interest in heritage conservation and monuments protection. Geophysical methods have been used for 20 years as powerful tools to assist in the curation of buildings. Ancient masonry bridges usually exhibit a complex structure/geometry. This complexity makes the use of combined geophysical methods highly necessary to obtain a meaningful model of the internal structure of such constructions and their environment. A high resolution geophysical survey was carried out at a stone arch bridge called Pont de Coq and located near Menerval, Normandy (France) in 2011. This decameter-sized bridge was built 400 years ago and crosses the Epte river, which is a tributary of the Seine river. The main objective of this work was to evaluate the structural state of the bridge and its vicinities. Two complementary methods were used : Electrical Resistivity tomography (ERT) and Ground Penetrating radar (GPR). Several profiles were realized along the road crossing the bridge and transversally to the construction, as well as on the two banks of the Epte river. High resolution electrical resistivity data were obtained both in the horizontal and vertical direction up to 8 meter-depth by two ERT methods (Wenner/Schlumberger and dipole-dipole). The GPR was used with shielded antennas at three different frequencies (200 MHz, 400 MHz and 1.5 GHz). This approach lead to the investigation of the subsurface up to approximately 6 meters-depth, with a resolution in the range of 0.04 m-0.40m. An excellent correlation is obtained between the ERT and the GPR methods, allowing us to propose a precise structural model of the Pont de Coq and to characterize the soil under the building. Several anomalies are observed within the roadway of the bridge at 50 cm-depth, as well as within the vaulting, corresponding to the presence of voids and a root network which lead to the slow destruction of the structure.

  11. Development and evaluation of a method for the quantification of airborne Thermoactinomyces vulgaris by real-time PCR.

    PubMed

    Betelli, Laetitia; Duquenne, Philippe; Grenouillet, Frédéric; Simon, Xavier; Scherer, Emeline; Géhin, Evelyne; Hartmann, Alain

    2013-01-01

    Actinomycetes are ubiquitous and some can be potentially pathogenic for humans when present in the air of some working areas. It's notably the case for Thermoactinomyces vulgaris in composting facilities where aerial concentrations can reach high values of more than 10(7) CFU·m(-3). Workers exposure to these inhalable bioaerosols can be the source of various diseases. The literature reveals a lack of knowledge about risk assessment: there is neither dose-effects relationship for most agents, or threshold limit value. The objectives of this study were to develop and standardize a method to quantify workers exposure to bioaerosols. We have developed and evaluated a method to quantify airborne T. vulgaris based on DNA extraction of aerial microbial communities and qPCR. Four DNA extraction protocols were compared, and primers and a hydrolysis probe were designed for specific amplification of the target species (gyrB gene). This method was compared to traditional methods based on viable or cultivable counting by epifluorescence microscopy or plating on selective media. The method was applied on environmental bioaerosols sampled under real exposure conditions in composting plants. We demonstrate that the method to quantify T. vulgaris in bioaerosols is specific, sensitive and repeatable. We demonstrate the occurrence and quantified T. vulgaris in the atmosphere of composting facilities with concentrations ranging from 3×10(2) to 3×10(6)×m(-3). PMID:23103956

  12. Evaluation of the potential of the Clare Basin, SW Ireland, for onshore carbon sequestration using electromagnetic geophysical methods

    NASA Astrophysics Data System (ADS)

    Llovet, Joan Campanya i.; Ogaya, Xenia; Jones, Alan G.; Rath, Volker; Ledo, Juanjo; McConnell, Brian

    2015-04-01

    Carbon capture, sequestration and long-term storage (CCS) is a critically important and intellectually and technologically challenging bridging technology for assisting humanity to migrate from its dependence on fossil fuels to green energy over the next half century. The IRECCSEM project (www.ireccsem.ie) is a Science Foundation Ireland Investigator Project to evaluate Ireland's potential for onshore carbon sequestration in saline aquifers by integrating new electromagnetic geophysical data with existing geophysical and geological data. The main goals of the project are to determine porosity and permeability values of the potential reservoir formation as well as to evaluate the integrity of the seal formation. During the summer of 2014, a magnetotelluric (MT) survey was carried out in the Carboniferous Clare Basin (SW Ireland). Data from a total of 140 sites were acquired, including audio-magnetotelluric (AMT), broadband magnetotelluric (BBMT) and long period magnetotelluric (LMT) data. These new data added to existing MT data acquired at 32 sites during a feasibility pilot survey conducted in 2010. The nominal space between the 2014 sites was 0.6 km between AMT sites, 1.2 km between BBMT sites and 8 km between LMT sites. The electrical resistivity distribution beneath the survey area was constrained using three different types of electromagnetic data: MT impedance tensor responses (Z), geomagnetic transfer functions (GTF) and inter-station horizontal magnetic transfer-functions (HMT). A newly-computed code based on the Generalized Archie's Law and available data from boreholes were used to relate the obtained geoelectrical model to rock properties (i.e. porosity and permeability). The results are compared to independent geological and geophysical data for superior interpretation.

  13. Comparing the suitability of geophysical methods in the study of a cave in marbles: A case study of Gruta de las Maravillas (Aracena, Southwest Spain)

    NASA Astrophysics Data System (ADS)

    José Martínez Moreno, Francisco; Galindo Zaldívar, Jesús; Pedrera Parias, Antonio; Ullod, Teresa Teixidó i.; Ruano Roca, Patricia; Peña Ruano, Jose Antonio; González Castillo, Lourdes; Ruiz Constan, Ana; López Chicano, Manuel; Martín Rosales, Wenceslao

    2014-05-01

    Different geophysical methods have been applied to determine the geometry of caves, considering the host rock, depth, dimension, presence of water and other parameters. The Gruta de las Maravillas cave is located in marbles interlayered with gneiss, quartzite and granodiorite along the suture between South Portuguese and Ossa Morena zone. This cave is probably formed as a consequence of the presence of pyrite and iron oxides mineralization that interacted with the surrounding marble host rocks. In order to analyze the continuity of the Gruta de las Maravillas cave (Aracena, southwest Spain) geophysical methods has been used on the known cave in order to check their suitability. These results allow investigating the prolongation of the cave in surrounding areas, performing a comprehensive study of the Cerro del Castillo hill containing the cavity. Microtopography with differential GPS and cave topography with an accuracy of 0.01 m were measured. The first geophysical method employed were a regional microgravity, with and SCINTREX CG-5 gravimeter that reaches an accuracy up to 0.001 mGal. In the obtained residual anomaly map, negative values are associated with negative density contrast, which are related to the known cave position. In addition, residual gravity minima suggest the presence of other unknown cavities. The anomalies attributed to possible new shallow and deep caves have been studied in a second step with the application of other eight detailed geophysical methods along profiles to test the response of each of them to the presence of cavities: microgravity, magnetic, electrical resistivity tomography, induced polarization, seismic P-waves velocity tomography, ray tracing coverage, common offset and ground-penetrating radar. Moreover, the known cave has walls covered with iron oxides that determine magnetic anomaly minima and intermediate resistivity values (~2000 ohm.m) on the ERT profiles versus the host marble rocks (~45000 ohm.m). After a detailed

  14. Monitoring a Field-Scale Biostimulation Pilot Project Using Cross-Hole Radar and Borehole Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Lane, J. W.; Day-Lewis, F. D.

    2004-12-01

    The U.S. Geological Survey (USGS) conducted geophysical investigations in support of a field-scale biostimulation pilot project at the Anoka County Riverfront Park (ACP), located downgradient of the Naval Industrial Reserve Ordnance Plant, in Fridley, Minnesota. The objective of the pilot project, conducted by the U.S. Naval Facilities Engineering Command, is to assess the applicability of subsurface injection of vegetable-oil emulsion (VOE) to promote microbial degradation of chlorinated hydrocarbons. Naturally occurring microbes, which use the VOE as substrate, ultimately break down chlorinated hydrocarbons into chloride, carbon dioxide, and water through oxidation-reduction reactions. To monitor movement of the VOE and changes in water chemistry resulting from VOE advection, dissolution, and (or) enhanced biological activity, the USGS acquired cross-hole zero-offset radar profiles; radar travel-time tomography data; and a suite of borehole geophysical logs, including electromagnetic (EM) induction conductivity. Data were collected during 5 site visits over 1.5 years. Preliminary results of these experiments have been reported elsewhere; this paper reports on the final analysis and combined interpretation of multiple data types, including application of petrophysical models to radar zero-offset profiles and tomograms to yield estimates of VOE saturation and changes in total-dissolved solids downgradient of the VOE injection zones. Comparison of pre- and post-injection datasets provides insight into the spatial and temporal distributions of both VOE and ground water with altered chemistry-information critical to understanding and verifying biodegradation of chlorinated hydrocarbons at the site. Cross-hole radar zero-offset slowness profiles and tomograms indicate the VOE remained close to the injection wells. Downgradient of the injection zones, radar amplitude profiles and EM logs indicate bulk formation electrical conductivity changes after VOE injection, which

  15. Fourth Airborne Geoscience Workshop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

  16. Geophex Airborne Unmanned Survey System

    SciTech Connect

    Won, I.L.; Keiswetter, D.

    1995-12-31

    Ground-based surveys place personnel at risk due to the proximity of buried unexploded ordnance (UXO) items or by exposure to radioactive materials and hazardous chemicals. The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide stand-off capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected. The Geophex Airborne Unmanned Survey System (GAUSS) is designed to detect and locate small-scale anomalies at hazardous sites using magnetic and electromagnetic survey techniques. The system consists of a remotely-piloted, radio-controlled, model helicopter (RCH) with flight computer, light-weight geophysical sensors, an electronic positioning system, a data telemetry system, and a computer base-station. The report describes GAUSS and its test results.

  17. A Novel Method for Assessment of Light Transmissivity in Forest Canopy from Full-Waveform Airborne LiDAR Data

    NASA Astrophysics Data System (ADS)

    Milenković, Milutin; Wagner, Wolfgang; Hollaus, Markus; Ressl, Camillo; Pfeifer, Norbert

    2016-04-01

    Air- and space-borne 2D imaging in visible and infrared domain of electromagnetic spectrum have been proven to be a reliable remote sensing techniques for forest monitoring and mapping. However, in contrast to the ranging techniques, 2D imaging over forest can not distinguish backscattering contributing from scattering elements at different ranges, e.g. from the forest canopy and the forest floor. Light transmissivity is a wavelength and directionally depended physical parameter which quantifies loss of light while traveling trough forest canopy, and thus, figures as a parameter in radiative transfer models when the scattering from these forest components should be quantified. This work proposes a novel method to derive the transmissivity of forest canopy based on small-footprint, full-waveform airborne LiDAR data. The method explores the energy balance at the ground boundary in the water cloud model applied on individual Gaussian clusters. The transmissivity map derived by the method proposed showed plausible results in comparison with orthophotos and ground images.

  18. The potential of near-surface geophysical methods in a hierarchical monitoring approach for the detection of shallow CO2 seeps at geological storage sites

    NASA Astrophysics Data System (ADS)

    Sauer, U.; Schuetze, C.; Dietrich, P.

    2013-12-01

    The MONACO project (Monitoring approach for geological CO2 storage sites using a hierarchic observation concept) aims to find reliable monitoring tools that work on different spatial and temporal scales at geological CO2 storage sites. This integrative hierarchical monitoring approach based on different levels of coverage and resolutions is proposed as a means of reliably detecting CO2 degassing areas at ground surface level and for identifying CO2 leakages from storage formations into the shallow subsurface, as well as CO2 releases into the atmosphere. As part of this integrative hierarchical monitoring concept, several methods and technologies from ground-based remote sensing (Open-path Fourier-transform infrared (OP-FTIR) spectroscopy), regional measurements (near-surface geophysics, chamber-based soil CO2 flux measurement) and local in-situ measurements (using shallow boreholes) will either be combined or used complementary to one another. The proposed combination is a suitable concept for investigating CO2 release sites. This also presents the possibility of adopting a modular monitoring concept whereby our monitoring approach can be expanded to incorporate other methods in various coverage scales at any temporal resolution. The link between information obtained from large-scale surveys and local in-situ monitoring can be realized by sufficient geophysical techniques for meso-scale monitoring, such as geoelectrical and self-potential (SP) surveys. These methods are useful for characterizing fluid flow and transport processes in permeable near-surface sedimentary layers and can yield important information concerning CO2-affected subsurface structures. Results of measurements carried out a natural analogue site in the Czech Republic indicate that the hierarchical monitoring approach represents a successful multidisciplinary modular concept that can be used to monitor both physical and chemical processes taking place during CO2 migration and seepage. The

  19. Sustainable urban development and geophysics

    NASA Astrophysics Data System (ADS)

    Liu, Lanbo; Chan, L. S.

    2007-09-01

    investigated [2]. The first objective of urban geophysics is to study systematically the geophysical fields in cities, searching for principles and processes governing the intensity and patterns of variation of the geophysical properties, as well as the potential consequences on the biosphere. Secondly, geophysics has already been found to be a useful tool for subsurface detection and investigation, hazard mitigation, and assessment of environmental contamination. Geophysicists have documented numerous cases of successful applications of geophysical techniques to solve problems related to hazard mitigation, safeguarding of lifeline infrastructure and urban gateways (air- and sea-ports, railway and highway terminals), archaeological and heritage surveys, homeland security, urban noise control, water supplies, sanitation and solid waste management etc. In contrast to conventional geophysical exploration, the undertaking of geophysical surveys in an urban setting faces many new challenges and difficulties. First of all, the ambient cultural noise in cities caused by traffic, electromagnetic radiation and electrical currents often produce undesirably strong interference with geophysical measurements. Secondly, subsurface surveys in an urban area are often targeted at the uppermost several metres of the ground, which are the most heterogeneous layers with many man-made objects. Thirdly, unlike conventional geophysical exploration which requires resolution in the order of metres, many urban geophysical surveys demand a resolution and precision in the order of centimetres or even millimetres. Finally restricted site access and limited time for conducting geophysical surveys, regulatory constraints, requirements for traffic management and special logistical arrangements impose additional difficulties. All of these factors point to the need for developing innovative research methods and geophysical instruments suitable for use in urban settings. This special issue on 'Sustainable urban

  20. Geophysical flight line flying and flight path recovery utilizing the Litton LTN-76 inertial navigation system

    SciTech Connect

    Mitkus, A.F.; Cater, D.; Farmer, P.F.; Gay, S.P. Jr.

    1981-11-01

    The Litton LTN-76 Inertial Navigation Systems (INS) with Inertial Track guidance System (ITGS) software is geared toward the airborne survey industry. This report is a summary of tests performed with the LTN-76 designed to fly an airborne geophysical survey as well as to recover the subsequent flight path utilizing INS derived coordinates.

  1. Constraining kimberlite geology through integration of geophysical, geological and geochemical methods: A case study of the Mothae kimberlite, northern Lesotho

    NASA Astrophysics Data System (ADS)

    Galloway, M.; Nowicki, T.; van Coller, B.; Mukodzani, B.; Siemens, K.; Hetman, C.; Webb, K.; Gurney, J.

    2009-11-01

    The Cretaceous Mothae kimberlite is located in northern Lesotho on the southeast margin of the Kaapvaal craton. Historical work suggests that Mothae has a low average diamond grade of ~ 3 cpht and the economic viability therefore depends on the presence of large, high quality (and thus value) diamonds as does that of the nearby Letseng Diamond Mine. Defining such a diamond population requires a very large and representative bulk sample. The near surface geology of the Mothae kimberlite was investigated using ground geophysical surveys, pit mapping, petrography, measurements of the mantle components and whole rock compositions. Integration of data from these different approaches clearly defines the outline of the kimberlite at the surface and permits definition, with varying confidence levels, of at least six geologically distinct domains within the body. The domains are defined primarily on the basis of variations in the relative abundances of certain mantle-derived minerals extracted from exploratory pit samples, supported to varying extents by geophysically-defined zones, variations in kimberlite type (established petrographically) and variations in whole rock composition. The domains are interpreted to reflect the presence of multiple phases of volcaniclastic kimberlite each with a potentially different diamond content. The map of the near surface geology constructed on the basis of the work described in this paper provides a valuable framework for planning of further drilling and sampling work aimed at constraining the diamond resource at Mothae. This study illustrates the value of an integrated, multidisciplinary approach to understanding the geology of a complex kimberlite body during the early stages of evaluation.

  2. Determining salinization extent, identifying salinity sources, and estimating chloride mass using surface, borehole, and airborne electromagnetic induction methods

    NASA Astrophysics Data System (ADS)

    Paine, Jeffrey G.

    2003-03-01

    Using an example from an oil field in the semiarid Red River basin in Texas, we show that electromagnetic (EM) methods are useful in locating salinized soil and water, determining salinization extent, identifying likely salinity sources, and estimating the total mass of chloride within a saline-water plume. Each of these aspects assists in managing salinization and assessing its impact. We used ground EM instruments to establish salinization boundaries and determine the range of electrical conductivity, airborne measurements to locate potential sources and quantify the lateral extent and intensity of salinization, and borehole measurements and time domain EM soundings to determine salinization depth and relate ground conductivity to chloride content. We estimated infiltration volume and total chloride mass in the plume from EM data and an empirical, site-specific chloride:conductivity ratio established from well data. Because the measured conductivity of water strongly correlates with total dissolved solids concentration, mass estimation could be extended to any ionic constituent that covaries linearly with total dissolved solids concentration. EM methods owe their success to the large increase in electrical conductivity that occurs where highly conductive, saline water infiltrates geologic materials having naturally low conductivities.

  3. Spectrum correction algorithm for detectors in airborne radioactivity monitoring equipment NH-UAV based on a ratio processing method

    NASA Astrophysics Data System (ADS)

    Cao, Ye; Tang, Xiao-Bin; Wang, Peng; Meng, Jia; Huang, Xi; Wen, Liang-Sheng; Chen, Da

    2015-10-01

    The unmanned aerial vehicle (UAV) radiation monitoring method plays an important role in nuclear accidents emergency. In this research, a spectrum correction algorithm about the UAV airborne radioactivity monitoring equipment NH-UAV was studied to measure the radioactive nuclides within a small area in real time and in a fixed place. The simulation spectra of the high-purity germanium (HPGe) detector and the lanthanum bromide (LaBr3) detector in the equipment were obtained using the Monte Carlo technique. Spectrum correction coefficients were calculated after performing ratio processing techniques about the net peak areas between the double detectors on the detection spectrum of the LaBr3 detector according to the accuracy of the detection spectrum of the HPGe detector. The relationship between the spectrum correction coefficient and the size of the source term was also investigated. A good linear relation exists between the spectrum correction coefficient and the corresponding energy (R2=0.9765). The maximum relative deviation from the real condition reduced from 1.65 to 0.035. The spectrum correction method was verified as feasible.

  4. Airborne Imagery

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ATM (Airborne Thematic Mapper) was developed for NSTL (National Space Technology Companies) by Daedalus Company. It offers expanded capabilities for timely, accurate and cost effective identification of areas with prospecting potential. A related system is TIMS, Thermal Infrared Multispectral Scanner. Originating from Landsat 4, it is also used for agricultural studies, etc.

  5. Continental crust: a geophysical approach

    SciTech Connect

    Meissner, R.

    1986-01-01

    This book develops an integrated and balanced picture of present knowledge of the continental crust. Crust and lithosphere are first defined, and the formation of crusts as a general planetary phenomenon is described. The background and methods of geophysical studies of the earth's crust and the collection of related geophysical parameters are examined. Creep and friction experiments and the various methods of radiometric age dating are addressed, and geophysical and geological investigations of the crustal structure in various age provinces of the continents are studied. Specific tectonic structures such as rifts, continental margins, and geothermal areas are discussed. Finally, an attempt is made to give a comprehensive view of the evolution of the continental crust and to collect and develop arguments for crustal accretion and recycling. 647 references.

  6. Assessment of the capabilities of the tICA and stICA methods for geophysical signal separation in GRACE data

    NASA Astrophysics Data System (ADS)

    Börgens, Eva; Rangelova, Elena; Sideris, Michael; Kusche, Jürgen

    2013-04-01

    We investigate the potential of the tICA and stICA methods for separating geophysical signals in GRACE gravity data. Since the start of the Gravity Recovery and Climate Experiment (GRACE) satellite mission in 2002, GRACE has provided us with global gravity data with a spatial resolution of a few hundred kilometers and a temporal resolution of one month, 10 days or even a week. These data represent the total, integrated gravity change inducing by mass signals related to hydrological processes, post glacial rebound (PGR), ice mass change and others. Isolating a particular mass signal may be accomplished by removing all others using geophysical background models, but these are usually not perfect. Therefore methods are required for separating data into the different geophysical signals on the basis of their statistical properties. To this end, we assess the potential of temporal Independent Component Analysis (tICA) and spatio-temporal Independent Component Analysis (stICA). The tICA method is based on the assumption of statistical independence of signals in the temporal domain and thus separates the GRACE-observed mass changes into maximal independent source signals. In comparison, stICA maximizes both the temporal and spatial independence. These two ICA methods are compared to the conventional Principle Component Analysis (PCA). We test them on GRACE data with respect to their ability to separate the hydrology signal from a trend signal not induced by hydrological processes, such as post glacial rebound (PGR). In addition, we investigate whether they are capable of separating the hydrological signal in annual and semi-annual components. We analyze both simulated and CSR GRACE water mass anomalies (January 2003 -December 2010). The simulated mass anomalies are composed of outputs of hydrologic, PGR, ice loss and ocean bottom pressure models. The two ICA methods are capable of separating the trend and annual hydrology signals both on a global and regional scale (North

  7. Monitoring airborne fungal spores in an experimental indoor environment to evaluate sampling methods and the effects of human activity on air sampling.

    PubMed Central

    Buttner, M P; Stetzenbach, L D

    1993-01-01

    Aerobiological monitoring was conducted in an experimental room to aid in the development of standardized sampling protocols for airborne microorganisms in the indoor environment. The objectives of this research were to evaluate the relative efficiencies of selected sampling methods for the retrieval of airborne fungal spores and to determine the effect of human activity on air sampling. Dry aerosols containing known concentrations of Penicillium chrysogenum spores were generated, and air samples were taken by using Andersen six-stage, Surface Air System, Burkard, and depositional samplers. The Andersen and Burkard samplers retrieved the highest numbers of spores compared with the measurement standard, an aerodynamic particle sizer located inside the room. Data from paired samplers demonstrated that the Andersen sampler had the highest levels of sensitivity and repeatability. With a carpet as the source of P. chrysogenum spores, the effects of human activity (walking or vacuuming near the sampling site) on air sampling were also examined. Air samples were taken under undisturbed conditions and after human activity in the room. Human activity resulted in retrieval of significantly higher concentrations of airborne spores. Surface sampling of the carpet revealed moderate to heavy contamination despite relatively low airborne counts. Therefore, in certain situations, air sampling without concomitant surface sampling may not adequately reflect the level of microbial contamination in indoor environments. PMID:8439150

  8. Airborne concentrations of peanut protein.

    PubMed

    Johnson, Rodney M; Barnes, Charles S

    2013-01-01

    Food allergy to peanut is a significant health problem, and there are reported allergic reactions to peanuts despite not eating or having physical contact with peanuts. It is presumed that an allergic reaction may have occurred from inhalation of airborne peanut allergens. The purpose of this study was to detect the possible concentrations of airborne peanut proteins for various preparations and during specific activities. Separate Ara h 1 and Ara h 2 monoclonal enzyme-linked immunosorbent assays and a polyclonal sandwich enzyme immunoassay for peanuts were used to detect the amount of airborne peanut protein collected using a Spincon Omni 3000 air collector (Sceptor Industries, Inc., Kansas City, MO) under different peanut preparation methods and situations. Air samples were measured for multiple peanut preparations and scenarios. Detectable amounts of airborne peanut protein were measured using a whole peanut immunoassay when removing the shells of roasted peanut. No airborne peanut allergen (Ara h 1 or Ara h 2) or whole peanut protein above the LLD was measured in any of the other peanut preparation collections. Ara h 1, Ara h 2, and polyclonal peanut proteins were detected from water used to boil peanuts. Small amounts of airborne peanut protein were detected in the scenario of removing shells from roasted peanuts; however, Ara h 1 and Ara h 2 proteins were unable to be consistently detected. Although airborne peanut proteins were detected, the concentration of airborne peanut protein that is necessary to elicit a clinical allergic reaction is unknown.

  9. Airborne concentrations of peanut protein.

    PubMed

    Johnson, Rodney M; Barnes, Charles S

    2013-01-01

    Food allergy to peanut is a significant health problem, and there are reported allergic reactions to peanuts despite not eating or having physical contact with peanuts. It is presumed that an allergic reaction may have occurred from inhalation of airborne peanut allergens. The purpose of this study was to detect the possible concentrations of airborne peanut proteins for various preparations and during specific activities. Separate Ara h 1 and Ara h 2 monoclonal enzyme-linked immunosorbent assays and a polyclonal sandwich enzyme immunoassay for peanuts were used to detect the amount of airborne peanut protein collected using a Spincon Omni 3000 air collector (Sceptor Industries, Inc., Kansas City, MO) under different peanut preparation methods and situations. Air samples were measured for multiple peanut preparations and scenarios. Detectable amounts of airborne peanut protein were measured using a whole peanut immunoassay when removing the shells of roasted peanut. No airborne peanut allergen (Ara h 1 or Ara h 2) or whole peanut protein above the LLD was measured in any of the other peanut preparation collections. Ara h 1, Ara h 2, and polyclonal peanut proteins were detected from water used to boil peanuts. Small amounts of airborne peanut protein were detected in the scenario of removing shells from roasted peanuts; however, Ara h 1 and Ara h 2 proteins were unable to be consistently detected. Although airborne peanut proteins were detected, the concentration of airborne peanut protein that is necessary to elicit a clinical allergic reaction is unknown. PMID:23406937

  10. Automated method for simultaneous lead and strontium isotopic analysis applied to rainwater samples and airborne particulate filters (PM10).

    PubMed

    Beltrán, Blanca; Avivar, Jessica; Mola, Montserrat; Ferrer, Laura; Cerdà, Víctor; Leal, Luz O

    2013-09-01

    A new automated, sensitive, and fast system for the simultaneous online isolation and preconcentration of lead and strontium by sorption on a microcolumn packed with Sr-resin using an inductively coupled plasma mass spectrometry (ICP-MS) detector was developed, hyphenating lab-on-valve (LOV) and multisyringe flow injection analysis (MSFIA). Pb and Sr are directly retained on the sorbent column and eluted with a solution of 0.05 mol L(-1) ammonium oxalate. The detection limits achieved were 0.04 ng for lead and 0.03 ng for strontium. Mass calibration curves were used since the proposed system allows the use of different sample volumes for preconcentration. Mass linear working ranges were between 0.13 and 50 ng and 0.1 and 50 ng for lead and strontium, respectively. The repeatability of the method, expressed as RSD, was 2.1% and 2.7% for Pb and Sr, respectively. Environmental samples such as rainwater and airborne particulate (PM10) filters as well as a certified reference material SLRS-4 (river water) were satisfactorily analyzed obtaining recoveries between 90 and 110% for both elements. The main features of the LOV-MSFIA-ICP-MS system proposed are the capability to renew solid phase extraction at will in a fully automated way, the remarkable stability of the column which can be reused up to 160 times, and the potential to perform isotopic analysis.

  11. Characterization of aquifer heterogeneity using Cyclostratigraphy and geophysical methods in the upper part of the Karstic Biscayne Aquifer, Southeastern Florida

    USGS Publications Warehouse

    Cunningham, Kevin J.; Carlson, Janine L.; Wingard, G. Lynn; Robinson, Edward; Wacker, Michael A.

    2004-01-01

    This report identifies and characterizes candidate ground-water flow zones in the upper part of the shallow, eogenetic karst limestone of the Biscayne aquifer in the Lake Belt area of north-central Miami-Dade County using cyclostratigraphy, ground-penetrating radar (GPR), borehole geophysical logs, and continuously drilled cores. About 60 miles of GPR profiles were used to calculate depths to shallow geologic contacts and hydrogeologic units, image karst features, and produce qualitative views of the porosity distribution. Descriptions of the lithology, rock fabrics, and cyclostratigraphy, and interpretation of depositional environments of 50 test coreholes were linked to the geophysical interpretations to provide an accurate hydrogeologic framework. Molluscan and benthic foraminiferal paleontologic constraints guided interpretation of depositional environments represented by rockfabric facies. Digital borehole images were used to characterize and quantify large-scale vuggy porosity. Preliminary heat-pulse flowmeter data were coupled with the digital borehole image data to identify candidate ground-water flow zones. Combined results show that the porosity and permeability of the karst limestone of the Biscayne aquifer have a highly heterogeneous and anisotropic distribution that is mostly related to secondary porosity overprinting vertical stacking of rock-fabric facies within high-frequency cycles (HFCs). This distribution of porosity produces a dual-porosity system consisting of diffuse-carbonate and conduit flow zones. The nonuniform ground-water flow in the upper part of the Biscayne aquifer is mostly localized through secondary permeability, the result of solution-enlarged carbonate grains, depositional textures, bedding planes, cracks, root molds, and paleokarst surfaces. Many of the resulting pore types are classified as touching vugs. GPR, borehole geophysical logs, and whole-core analyses show that there is an empirical relation between formation porosity

  12. Formal methods and their role in digital systems validation for airborne systems

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1995-01-01

    This report is based on one prepared as a chapter for the FAA Digital Systems Validation Handbook (a guide to assist FAA certification specialists with advanced technology issues). Its purpose is to explain the use of formal methods in the specification and verification of software and hardware requirements, designs, and implementations; to identify the benefits, weaknesses, and difficulties in applying these methods to digital systems used in critical applications; and to suggest factors for consideration when formal methods are offered in support of certification. The presentation concentrates on the rationale for formal methods and on their contribution to assurance for critical applications within a context such as that provided by DO-178B (the guidelines for software used on board civil aircraft); it is intended as an introduction for those to whom these topics are new.

  13. Geochemical Characterization Using Geophysical Data and Markov Chain Monte Carlo Methods: A Case Study at the South Oyster Bacterial Transport Site in Virginia

    SciTech Connect

    Chen, Jinsong; Hubbard, Susan; Rubin, Yoram; Murray, Christopher J.; Roden, Eric E.; Majer, Ernest L.

    2004-12-22

    The paper demonstrates the use of ground-penetrating radar (GPR) tomographic data for estimating extractable Fe(II) and Fe(III) concentrations using a Markov chain Monte Carlo (MCMC) approach, based on data collected at the DOE South Oyster Bacterial Transport Site in Virginia. Analysis of multidimensional data including physical, geophysical, geochemical, and hydrogeological measurements collected at the site shows that GPR attenuation and lithofacies are most informative for the estimation. A statistical model is developed for integrating the GPR attenuation and lithofacies data. In the model, lithofacies is considered as a spatially correlated random variable and petrophysical models for linking GPR attenuation to geochemical parameters were derived from data at and near boreholes. Extractable Fe(II) and Fe(III) concentrations at each pixel between boreholes are estimated by conditioning to the co-located GPR data and the lithofacies measurements along boreholes through spatial correlation. Cross-validation results show that geophysical data, constrained by lithofacies, provided information about extractable Fe(II) and Fe(III) concentration in a minimally invasive manner and with a resolution unparalleled by other geochemical characterization methods. The developed model is effective and flexible, and should be applicable for estimating other geochemical parameters at other sites.

  14. INEL cold test pit demonstration of improvements in information derived from non-intrusive geophysical methods over buried waste sites. Phase 1, Final report

    SciTech Connect

    Not Available

    1993-09-08

    The objectives of this research project were to lay the foundation for further improvement in the use of geophysical methods for detection of buried wastes, and to increase the information content derived from surveys. Also, an important goal was to move from mere detection to characterization of buried wastes. The technical approach to achieve these objectives consisted of: (1) Collect a data set of high spatial density; (2) Acquire data with multiple sensors and integrate the interpretations inferred from the various sensors; (3) Test a simplified time domain electromagnetic system; and (4) Develop imaging and display formats of geophysical data readily understood by environmental scientists and engineers. The breadth of application of this work is far reaching. Not only are uncontrolled waste pits and trenches, abandoned underground storage tanks, and pipelines found throughout most US DOE facilities, but also at military installations and industrial facilities. Moreover, controlled land disposal sites may contain ``hot spots`` where drums and hazardous material may have been buried. The technologies addressed by the R&D will benefit all of these activities.

  15. Agricultural Geophysics: Past, present, and future

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods are becoming an increasingly valuable tool for agricultural applications. Agricultural geophysics investigations are commonly (although certainly not always) focused on delineating small- and/or large-scale objects/features within the soil profile (~ 0 to 2 m depth) over very lar...

  16. Fiber Optic Geophysics Sensor Array

    NASA Astrophysics Data System (ADS)

    Grochowski, Lucjan

    1989-01-01

    The distributed optical sensor arrays are analysed in view of specific needs of 3-D seismic explorations methods. There are compared advantages and disadventages of arrays supported by the sensors which are modulated in intensity and phase. In these systems all-fiber optic structures and their compabilities with digital geophysic formats are discussed. It was shown that the arrays based on TDM systems with the intensity modulated sensors are economically and technically the best matched for geophysic systems supported by a large number of the sensors.

  17. AfricaArray International Geophysics Field School: Applications of Near Surface Geophysics to challenges encountered in mine planning

    NASA Astrophysics Data System (ADS)

    Webb, S. J.; Jones, M. Q.; Durrheim, R. J.; Nyblade, A.; Snyman, Q.

    2012-12-01

    Hard rock exploration and mining presents many opportunities for the effective use of near surface geophysics. For over 10 years the AfricaArray international geophysics field school has been hosted at a variety of mines in South Africa. While the main objective of the field school is practical training for the next generation of geophysicists, being hosted at a mine has allowed us to investigate applications of near surface geophysics in the early stages of mine planning and development as geophysics is often cheaper and faster than drilling. Several applications include: detailed delineation of dykes and stringer dykes, physical property measurements on drill core for modeling and marker horizons, determination of overburden thickness, locations of water and faults. Dolerite dykes are usually magnetic and are associated with loss of ground (i.e. where the dyke replaces the ore and thus reduces the amount of ore available) and safety/stability concerns. Thus the accurate mapping of dykes and narrow stringers that are associated with them are crucial to the safe planning of a mine. We have acquired several case studies where ground magnetic surveys have greatly improved on the resolution and detail of airborne magnetic surveys in regions of complicated dyke swarms. In many cases, thin stringer dykes of less than 5 cm have been detected. Physical property measurements of these dykes can be used to distinguish between different ages of dykes. It is important to accurately determine overburden thickness when planning an open pit mine as this directly affects the cost of development. Depending on the nature of the overburden, both refraction seismic and or DC resistivity can provide continuous profiling in the area of interest that fills in gaps between boreholes. DC resistivity is also effective for determining water associated with dykes and structures that may affect mine planning. The field school mainly addresses the training of a variety of students. The core

  18. Constructing Regional Groundwater Models from Geophysical Data of Varying Type, Age, and Quality

    NASA Astrophysics Data System (ADS)

    Christiansen, A. V.; Auken, E.; Marker, P. A.; Vilhelmsen, T. N.; Foged, N.; Wernberg, T.; Bauer-Gottwein, P.

    2015-12-01

    Regional hydrological models are important tools in water resources management, but prediction uncertainties are often high due to non-uniqueness of the hydrostratigraphical model. This model is often based on borehole lithology only. However, a much better resolution can be obtained from large geophysical datasets covering the entire domain. Using boreholes to link between hydrostratigraphical classes and resistivity is efficient and emphasizes the need for an all-inclusive data interpretation procedure that can be integrated in groundwater model calibration. We present an automatic method for parameterization of a 3D model of the subsurface, integrating lithological information from boreholes with resistivity models. The objective is to create a direct input to regional groundwater models for sedimentary areas, where the sand/clay distribution governs the groundwater flow. The resistivity input is all-inclusive in the sense that we include data from a variety of instruments (DC and EM, ground-based and airborne), with a varying spatial density and varying ages and quality. The coupling between hydrological and geophysical parameters is managed using a translator function with spatially variable parameters, which is calibrated against observed lithological data. In other words, the translator function interprets the geophysical resistivities into a 3D clay fraction model and the 3D clay fraction model is then turned into a zonation for the hydrological model by a K-means clustering. We present the methodology by show-casing a study from Denmark were a regional groundwater model is constructed by including lithological information from 3100 boreholes over an 710 sqkm area. The geophysical models spans more than 30 years of data collection and includes approx. 225,000 DC models, and 35,000 EM models, airborne as well as groundbased. The final model was calibrated giving parameters that were comparable with existing models based on thorough and time-consuming manual

  19. Monitoring method for airborne glymes and its application in fuel exhaust emission measurement.

    PubMed

    Cao, X L; Zhu, J

    2001-11-01

    A monitoring method based on solvent extraction of adsorbed target glymes followed by gas chromatograph-mass spectrometry GC-MS analysis was developed for seven glymes, namely ethylene glycol dimethyl ether, propylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. The best recoveries of target glymes were achieved when using a combination of sample collection medium of graphitised carbon black (GCB) with a solvent mixture of methylene chloride and methanol (95/5, v/v). Method detection limits ranged from 1.5 microg/m3 for diethylene glycol diethyl ether to 13.2 microg/m3 for ethylene glycol diethyl ether based on a sample volume of 3.4 1. Using this method, diethylene glycol dimethyl ether and diethylene glycol diethyl ether were detected and measured successfully in diluted vehicle exhausts in diesel fuel engine tests.

  20. Global Estimates of Fine Particulate Matter Using a Combined Geophysical-Statistical Method with Information from Satellites, Models, and Monitors

    NASA Technical Reports Server (NTRS)

    Van Donkelaar, Aaron; Martin, Randall V.; Brauer, Michael; Hsu, N. Christina; Kahn, Ralph A.; Levy, Robert C.; Lyapustin, Alexei; Sayer, Andrew M.; Winker, David M.

    2016-01-01

    We estimated global fine particulate matter (PM(sub 2.5)) concentrations using information from satellite-, simulation- and monitor-based sources by applying a Geographically Weighted Regression (GWR) to global geophysically-based satellite-derived PM(sub 2.5) estimates. Aerosol optical depth from multiple satellite products (MISR, MODIS Dark Target, MODIS and SeaWiFS Deep Blue, and MODIS MAIAC) was combined with simulation (GEOS-Chem) based upon their relative uncertainties as determined using ground-based sun photometer (AERONET) observations for 1998-2014. The GWR predictors included simulated aerosol composition and land use information. The resultant PM(sub 2.5) estimates were highly consistent (R(sup 2) equals 0.81) with out-of-sample cross-validated PM(sub 2.5) concentrations from monitors. The global population-weighted annual average PM(sub 2.5) concentrations were 3-fold higher than the 10 micrograms per cubic meter WHO guideline, driven by exposures in Asian and African regions. Estimates in regions with high contributions from mineral dust were associated with higher uncertainty, resulting from both sparse ground-based monitoring, and challenging conditions for retrieval and simulation. This approach demonstrates that the addition of even sparse ground-based measurements to more globally continuous PM(sub 2.5) data sources can yield valuable improvements to PM(sub 2.5) characterization on a global scale.

  1. Global Estimates of Fine Particulate Matter using a Combined Geophysical-Statistical Method with Information from Satellites, Models, and Monitors.

    PubMed

    van Donkelaar, Aaron; Martin, Randall V; Brauer, Michael; Hsu, N Christina; Kahn, Ralph A; Levy, Robert C; Lyapustin, Alexei; Sayer, Andrew M; Winker, David M

    2016-04-01

    We estimated global fine particulate matter (PM2.5) concentrations using information from satellite-, simulation- and monitor-based sources by applying a Geographically Weighted Regression (GWR) to global geophysically based satellite-derived PM2.5 estimates. Aerosol optical depth from multiple satellite products (MISR, MODIS Dark Target, MODIS and SeaWiFS Deep Blue, and MODIS MAIAC) was combined with simulation (GEOS-Chem) based upon their relative uncertainties as determined using ground-based sun photometer (AERONET) observations for 1998-2014. The GWR predictors included simulated aerosol composition and land use information. The resultant PM2.5 estimates were highly consistent (R(2) = 0.81) with out-of-sample cross-validated PM2.5 concentrations from monitors. The global population-weighted annual average PM2.5 concentrations were 3-fold higher than the 10 μg/m(3) WHO guideline, driven by exposures in Asian and African regions. Estimates in regions with high contributions from mineral dust were associated with higher uncertainty, resulting from both sparse ground-based monitoring, and challenging conditions for retrieval and simulation. This approach demonstrates that the addition of even sparse ground-based measurements to more globally continuous PM2.5 data sources can yield valuable improvements to PM2.5 characterization on a global scale. PMID:26953851

  2. COMPARISON OF METHODS FOR DETECTION AND ENUMERATION OF AIRBORNE MICROORGANISMS COLLECTED BY LIQUID IMPINGEMENT

    EPA Science Inventory

    Bacterial agents and cell components can be spread as bioaerosols, producing infections and asthmatic problems. This study compares four methods for the detection and enumeration of aerosolized bacteria collected in an AGI-30 impinger. Changes in the total and viable concentratio...

  3. The impact of particle size selective sampling methods on occupational assessment of airborne beryllium particulates.

    PubMed

    Sleeth, Darrah K

    2013-05-01

    In 2010, the American Conference of Governmental Industrial Hygienists (ACGIH) formally changed its Threshold Limit Value (TLV) for beryllium from a 'total' particulate sample to an inhalable particulate sample. This change may have important implications for workplace air sampling of beryllium. A history of particle size-selective sampling methods, with a special focus on beryllium, will be provided. The current state of the science on inhalable sampling will also be presented, including a look to the future at what new methods or technology may be on the horizon. This includes new sampling criteria focused on particle deposition in the lung, proposed changes to the existing inhalable convention, as well as how the issues facing beryllium sampling may help drive other changes in sampling technology.

  4. Quantifying greenhouse gas emissions from coal fires using airborne and ground-based methods

    USGS Publications Warehouse

    Engle, M.A.; Radke, L.F.; Heffern, E.L.; O'Keefe, J. M. K.; Smeltzer, C.D.; Hower, J.C.; Hower, J.M.; Prakash, A.; Kolker, A.; Eatwell, R.J.; ter, Schure A.; Queen, G.; Aggen, K.L.; Stracher, G.B.; Henke, K.R.; Olea, R.A.; Roman-Colon, Y.

    2011-01-01

    Coal fires occur in all coal-bearing regions of the world and number, conservatively, in the thousands. These fires emit a variety of compounds including greenhouse gases. However, the magnitude of the contribution of combustion gases from coal fires to the environment is highly uncertain, because adequate data and methods for assessing emissions are lacking. This study demonstrates the ability to estimate CO2 and CH4 emissions for the Welch Ranch coal fire, Powder River Basin, Wyoming, USA, using two independent methods: (a) heat flux calculated from aerial thermal infrared imaging (3.7-4.4td-1 of CO2 equivalent emissions) and (b) direct, ground-based measurements (7.3-9.5td-1 of CO2 equivalent emissions). Both approaches offer the potential for conducting inventories of coal fires to assess their gas emissions and to evaluate and prioritize fires for mitigation. ?? 2011.

  5. Comparison of methods for detection and enumeration of airborne microorganisms collected by liquid impingement.

    PubMed Central

    Terzieva, S; Donnelly, J; Ulevicius, V; Grinshpun, S A; Willeke, K; Stelma, G N; Brenner, K P

    1996-01-01

    Bacterial agents and cell components can be spread as bioaerosols, producing infections and asthmatic problems. This study compares four methods for the detection and enumeration of aerosolized bacteria collected in an AGI-30 impinger. Changes in the total and viable concentrations of Pseudomonas fluorescens in the collection fluid with respect to time of impingement were determined. Two direct microscopic methods (acridine orange and BacLight) and aerodynamic aerosol-size spectrometry (Aerosizer) were employed to measure the total bacterial cell concentrations in the impinger collection fluid and the air, respectively. These data were compared with plate counts on selective (MacConkey agar) and nonselective (Trypticase soy agar) media, and the percentages of culturable cells in the collection fluid and the bacterial injury response to the impingement process were determined'. The bacterial collection rate was found to be relatively unchanged during 60 min of impingement. The aerosol measurements indicated an increased amount of cell fragments upstream of the impinger due to continuous bacterial nebulization. Some of the bacterial clusters, present in the air upstream of the impinger, deagglomerated during impingement, thus increasing the total bacterial count by both direct microscopic methods. The BacLight staining technique was also used to determine the changes in viable bacterial concentration during the impingement process. The percentage of viable bacteria, determined as a ratio of BacLight live to total counts was only 20% after 60 min of sampling. High counts on Trypticase soy agar indicated that most of the injured cells could recover. On the other hand, the counts from the MacConkey agar were very low, indicating that most of the cells were structurally damaged in the impinger. The comparison of data on the percentage of injured bacteria obtained by the traditional plate count with the data on percentage of nonviable bacteria obtained by the Bac

  6. Tillandsia stricta Sol (Bromeliaceae) leaves as monitors of airborne particulate matter-A comparative SEM methods evaluation: Unveiling an accurate and odd HP-SEM method.

    PubMed

    de Oliveira, Martha Lima; de Melo, Edésio José Tenório; Miguens, Flávio Costa

    2016-09-01

    Airborne particulate matter (PM) has been included among the most important air pollutants by governmental environment agencies and academy researchers. The use of terrestrial plants for monitoring PM has been widely accepted, particularly when it is coupled with SEM/EDS. Herein, Tillandsia stricta leaves were used as monitors of PM, focusing on a comparative evaluation of Environmental SEM (ESEM) and High-Pressure SEM (HPSEM). In addition, specimens air-dried at formaldehyde atmosphere (AD/FA) were introduced as an SEM procedure. Hydrated specimen observation by ESEM was the best way to get information from T. stricta leaves. If any artifacts were introduced by AD/FA, they were indiscernible from those caused by CPD. Leaf anatomy was always well preserved. PM density was determined on adaxial and abaxial leaf epidermis for each of the SEM proceedings. When compared with ESEM, particle extraction varied from 0 to 20% in air-dried leaves while 23-78% of particles deposited on leaves surfaces were extracted by CPD procedures. ESEM was obviously the best choice over other methods but morphological artifacts increased in function of operation time while HPSEM operation time was without limit. AD/FA avoided the shrinkage observed in the air-dried leaves and particle extraction was low when compared with CPD. Structural and particle density results suggest AD/FA as an important methodological approach to air pollution biomonitoring that can be widely used in all electron microscopy labs. Otherwise, previous PM assessments using terrestrial plants as biomonitors and performed by conventional SEM could have underestimated airborne particulate matter concentration. PMID:27357408

  7. Tillandsia stricta Sol (Bromeliaceae) leaves as monitors of airborne particulate matter-A comparative SEM methods evaluation: Unveiling an accurate and odd HP-SEM method.

    PubMed

    de Oliveira, Martha Lima; de Melo, Edésio José Tenório; Miguens, Flávio Costa

    2016-09-01

    Airborne particulate matter (PM) has been included among the most important air pollutants by governmental environment agencies and academy researchers. The use of terrestrial plants for monitoring PM has been widely accepted, particularly when it is coupled with SEM/EDS. Herein, Tillandsia stricta leaves were used as monitors of PM, focusing on a comparative evaluation of Environmental SEM (ESEM) and High-Pressure SEM (HPSEM). In addition, specimens air-dried at formaldehyde atmosphere (AD/FA) were introduced as an SEM procedure. Hydrated specimen observation by ESEM was the best way to get information from T. stricta leaves. If any artifacts were introduced by AD/FA, they were indiscernible from those caused by CPD. Leaf anatomy was always well preserved. PM density was determined on adaxial and abaxial leaf epidermis for each of the SEM proceedings. When compared with ESEM, particle extraction varied from 0 to 20% in air-dried leaves while 23-78% of particles deposited on leaves surfaces were extracted by CPD procedures. ESEM was obviously the best choice over other methods but morphological artifacts increased in function of operation time while HPSEM operation time was without limit. AD/FA avoided the shrinkage observed in the air-dried leaves and particle extraction was low when compared with CPD. Structural and particle density results suggest AD/FA as an important methodological approach to air pollution biomonitoring that can be widely used in all electron microscopy labs. Otherwise, previous PM assessments using terrestrial plants as biomonitors and performed by conventional SEM could have underestimated airborne particulate matter concentration.

  8. Fiber optic geophysical sensors

    DOEpatents

    Homuth, Emil F.

    1991-01-01

    A fiber optic geophysical sensor in which laser light is passed through a sensor interferometer in contact with a geophysical event, and a reference interferometer not in contact with the geophysical event but in the same general environment as the sensor interferometer. In one embodiment, a single tunable laser provides the laser light. In another embodiment, separate tunable lasers are used for the sensor and reference interferometers. The invention can find such uses as monitoring for earthquakes, and the weighing of objects.

  9. Application of near surface geophysical methods to image water table response in an Alpine Meadow, Northern California.

    NASA Astrophysics Data System (ADS)

    Ayers, M.; Blacic, T. M.; Craig, M. S.; Yarnell, S. M.

    2015-12-01

    Meadows are recognized for their value to the ecological, hydrologic, and aesthetic functions of a watershed. As natural water retention sinks, meadows attenuate floods, improve water quality and support herbaceous vegetation that stabilize streambanks and promote high biodiversity. Alpine meadows are especially vital, serving as freshwater sources and distributing to lower lying provinces through ground and surface water interaction. These complexes are highly vulnerable to drought conditions, altered seasonal precipitation patterns, and mismanaged land use. One such location, Van Norden meadow located in the Donner Summit area west of Lake Tahoe, is one of the largest sub-alpine meadows in the Sierra Nevada mountain range of Northern California. Van Norden meadow offers a natural hydrologic laboratory. Ownership transfer of the area from a local land trust to the Forestry Service requires restoration toward natural meadow conditions, and involves notching the dam in 2016 to reduce currently impounded water volumes from 250 to less than 50 acre-feet. To monitor the effects of notching the dam on the upstream meadow conditions, better understanding of the surface and groundwater hydrology both pre-and post-base level alteration is required. Comprehensive understanding of groundwater flux that supports meadow reaches relies on knowledge of their often complex stratigraphic and structural subsurface framework. In recent years hydrogeophysics has emphasized the combination of near surface geophysical techniques, collaborated with well and borehole measures, to qualitatively define these parameters. Building on a preliminary GPR investigation conducted in 2014, in which 44 270 MHz transect lines were collected, we returned to Van Norden meadow in late summer 2015 to collect lower frequency GPR (50 and 100 MHz) and electrical resistivity profiles to better define the groundwater table, sedimentary, and structural features of the meadow.

  10. Inverse spatial principal component analysis for geophysical survey data interpolation

    NASA Astrophysics Data System (ADS)

    Li, Qingmou; Dehler, Sonya A.

    2015-04-01

    The starting point for data processing, visualization, and overlay with other data sources in geological applications often involves building a regular grid by interpolation of geophysical measurements. Typically, the sampling interval along survey lines is much higher than the spacing between survey lines because the geophysical recording system is able to operate with a high sampling rate, while the costs and slower speeds associated with operational platforms limit line spacing. However, currently available interpolating methods often smooth data observed with higher sampling rate along a survey line to accommodate the lower spacing across lines, and much of the higher resolution information is not captured in the interpolation process. In this approach, a method termed as the inverse spatial principal component analysis (isPCA) is developed to address this problem. In the isPCA method, a whole profile observation as well as its line position is handled as an entity and a survey collection of line entities is analyzed for interpolation. To test its performance, the developed isPCA method is used to process a simulated airborne magnetic survey from an existing magnetic grid offshore the Atlantic coast of Canada. The interpolation results using the isPCA method and other methods are compared with the original survey grid. It is demonstrated that the isPCA method outperforms the Inverse Distance Weighting (IDW), Kriging (Geostatistical), and MINimum Curvature (MINC) interpolation methods in retaining detailed anomaly structures and restoring original values. In a second test, a high resolution magnetic survey offshore Cape Breton, Nova Scotia, Canada, was processed and the results are compared with other geological information. This example demonstrates the effective performance of the isPCA method in basin structure identification.

  11. Study of the Use of an Airborne Electromagnetic Method to Extract Data on Areas Likely to Cause Landslides

    NASA Astrophysics Data System (ADS)

    Takahara, T.; Seto, S.; Noike, K.; Mori, K.; Kinoshita, A.; Mizuno, H.; Kawato, K.; Okumura, M.; Kageura, R.

    2015-12-01

    In recent years, there have been studies of the use of airborne electromagnetic methods to extract data on the areas likely to cause deep-seated catastrophic landslides or shallow landslides. In this data extraction, it is important to show the underground geological structures and hydrological conditions by using specific electrical resistance. However, there have been insufficient studies in this field. Therefore, in this study, we focused on areas in which deep-seated catastrophic landslides or shallow landslides had occurred in the past. We then used the distributions of specific electrical resistance to study the geological structure and hydrological conditions of areas likely to cause landslides. First, in each study area, we tried to understand the geological planar distributions and the characteristics of the specific electrical resistance. Next, we tried to use the specific electrical resistance to understand the characteristics of the landslides areas. Last, we used the results to determine the geological distribution and hydrological condition of areas likely to cause deep-seated catastrophic landslides or shallow landslides. We obtained the following results. In areas in which deep-seated catastrophic landslides had occurred, we found two distribution patterns of specific electrical resistance. In the first pattern, the specific electrical resistance changed suddenly around the face of the collapse. In the second pattern, the specific resistance was low overall in areas of high groundwater. In areas in which shallow landslides had occurred, we found that the contour of the specific electrical resistance was vertical and that groundwater was able to flow easily from the geologic boundary.

  12. Comparison of Methods to Map and Measure River Terraces using High-Resolution Airborne LiDAR Data

    NASA Astrophysics Data System (ADS)

    Hopkins, A. J.; Snyder, N. P.

    2013-12-01

    Fluvial terraces are important recorders of land-use, climate, and tectonic history that form in both erosional and depositional landscapes and consist of a flat surface bounded by valley walls and a steep-sloping scarp adjacent to the river channel. Combining these defining characteristics with high-resolution digital elevation models (DEMs) derived from airborne light detection and ranging (lidar) surveys, several methods have been developed to identify and map terraces. The goals of this research are to compare some of these existing techniques and develop an objective approach to map terraces over entire watersheds using lidar DEMs. Additionally, we aim to quantify the thickness and volume of fill terrace deposits. Our preliminary application is to the Sheepscot River watershed, Maine, where strath and fill terraces are present and record Pleistocene deglaciation, Holocene eustatic forcing, and Anthropocene land-use change. We identify terraces along the longitudinal profile using an algorithm developed by Finnegan and Balco (2013), that computes the elevation frequency distribution at regularly spaced cross-sections normal to the channel. Next, we delineate terrace spatial extent using three separate methodologies: (1) image processing using Matlab, (2) feature classification algorithms developed by Wood (1996), and (3) image interpretation using manually placed points on known terraces to construct interpolated surfaces (Walter and Merritts, 2008). Lastly, we determine the thickness and volume of fill terrace sediments by subtracting an interpolated, adjacent water surface elevation from the defined terrace points. We compare our LiDAR-based results with field mapping, stratigraphic columns of terrace landforms, and ground penetrating radar over terrace surfaces. These findings suggest powerful new ways to rapidly analyze landscape history over large regions using high-resolution lidar DEMs, with less reliance on detailed and costly field data collection.

  13. Accuracy, precision, and method detection limits of quantitative PCR for airborne bacteria and fungi.

    PubMed

    Hospodsky, Denina; Yamamoto, Naomichi; Peccia, Jordan

    2010-11-01

    Real-time quantitative PCR (qPCR) for rapid and specific enumeration of microbial agents is finding increased use in aerosol science. The goal of this study was to determine qPCR accuracy, precision, and method detection limits (MDLs) within the context of indoor and ambient aerosol samples. Escherichia coli and Bacillus atrophaeus vegetative bacterial cells and Aspergillus fumigatus fungal spores loaded onto aerosol filters were considered. Efficiencies associated with recovery of DNA from aerosol filters were low, and excluding these efficiencies in quantitative analysis led to underestimating the true aerosol concentration by 10 to 24 times. Precision near detection limits ranged from a 28% to 79% coefficient of variation (COV) for the three test organisms, and the majority of this variation was due to instrument repeatability. Depending on the organism and sampling filter material, precision results suggest that qPCR is useful for determining dissimilarity between two samples only if the true differences are greater than 1.3 to 3.2 times (95% confidence level at n = 7 replicates). For MDLs, qPCR was able to produce a positive response with 99% confidence from the DNA of five B. atrophaeus cells and less than one A. fumigatus spore. Overall MDL values that included sample processing efficiencies ranged from 2,000 to 3,000 B. atrophaeus cells per filter and 10 to 25 A. fumigatus spores per filter. Applying the concepts of accuracy, precision, and MDL to qPCR aerosol measurements demonstrates that sample processing efficiencies must be accounted for in order to accurately estimate bioaerosol exposure, provides guidance on the necessary statistical rigor required to understand significant differences among separate aerosol samples, and prevents undetected (i.e., nonquantifiable) values for true aerosol concentrations that may be significant.

  14. Three-Dimensional Joint Geophysical Imaging Using an Advanced Multivariate Inversion Technique: the Method and its Application to the Utah area, United States

    NASA Astrophysics Data System (ADS)

    Zhang, Haijiang; Maceira, Monica; Benson, Thomas; Nafi Toksoz, M.

    2010-05-01

    We present an advanced multivariate inversion technique to generate a realistic, comprehensive, and high-resolution 3D model of the seismic structure of the crust and upper mantle. The model satisfies several independent geophysical datasets including seismic surface wave dispersion measurements, gravity, and seismic arrival time. The joint inversion method takes advantage of strengths of individual data sets and is able to better constrain the seismic velocity models from shallower to greater depths. To combine different geophysical datasets into a common system, we design an optimal weighting scheme that is based on relative uncertainties of individual observations, their sensitivities to model parameters, and the trade-off of different data fitting. We apply this joint inversion method to determine the 3D Vp and Vs models of the Utah area. The seismic body wave arrival times are assembled from waveform data recorded by the University of Utah Seismograph Stations (UUSS) regional network and the EarthScope/USArray network. The surface wave dispersion measurements are obtained from the ambient noise tomography study by the University of Colorado group using EarthScope/USArray stations. The gravity data for the Utah area is extracted from the North American Gravity Database managed by the University of Texas at El Paso. The joint inversions using two individual data sets such as seismic arrival time and gravity data, as well as seismic surface wave and gravity data indicate strong low velocity anomalies in middle crust beneath some known geothermal sites in Utah. The joint inversion of all three data sets will be presented and is expected to produce a reasonably well-constrained velocity structure of the Utah area, which is helpful for characterizing and exploring existing and potential geothermal reservoirs.

  15. Modified cavity attenuated phase shift (CAPS) method for airborne aerosol light extinction measurement

    NASA Astrophysics Data System (ADS)

    Perim de Faria, Julia; Bundke, Ulrich; Freedman, Andrew; Petzold, Andreas

    2015-04-01

    first set of tests, the robustness of the method was demonstrated down to pressure levels below 200 hPa, using air and CO2 as test gases. Rayleigh scattering cross-section values for both gases deviated by less than 5 % from literature data for all investigated pressure levels.(2) The measurement of aerosol particles at lower pressure levels required the modification of the air flow handling. A new flow scheme using mass flow controllers and a revised vacuum pump set-up was developed and successfully tested. The overall reduction of the instrument noise level to values less than 0.15 Mm-1 was achieved. (3) Polydisperse laboratory-generated ammonium sulphate particles and monodisperse polystyrene latex spheres where used to evaluate the instrument operation for the pressure range from 1000 hPa to less than 200 hPa against an optical particle counter. Reference aerosol extinction coefficients were calculated from measured size distributions, using Mie theory. We found less than 10 % deviation between the CAPS PMex instrument response and calcuated extinction coefficients over the investigated pressure range.

  16. Fundamentals of Geophysics

    NASA Astrophysics Data System (ADS)

    Lowrie, William

    1997-10-01

    This unique textbook presents a comprehensive overview of the fundamental principles of geophysics. Unlike most geophysics textbooks, it combines both the applied and theoretical aspects to the subject. The author explains complex geophysical concepts using abundant diagrams, a simplified mathematical treatment, and easy-to-follow equations. After placing the Earth in the context of the solar system, he describes each major branch of geophysics: gravitation, seismology, dating, thermal and electrical properties, geomagnetism, paleomagnetism and geodynamics. Each chapter begins with a summary of the basic physical principles, and a brief account of each topic's historical evolution. The book will satisfy the needs of intermediate-level earth science students from a variety of backgrounds, while at the same time preparing geophysics majors for continued study at a higher level.

  17. Geohydrologic assessment of fractured crystalline bedrock on the southern part of Manhattan, New York, through the use of advanced borehole geophysical methods

    NASA Astrophysics Data System (ADS)

    Stumm, F.; Chu, A.; Joesten, P. K.; Lane, J. W., Jr.

    2007-09-01

    Advanced borehole-geophysical methods were used to assess the geohydrology of fractured crystalline bedrock in 31 of 64 boreholes on the southern part of Manhattan Island, NY in preparation of the construction of a new water tunnel. The study area is located in a highly urbanized part of New York City. The boreholes penetrated gneiss, schist, and other crystalline bedrock that has an overall southwest-to northwest-dipping foliation. Most of the fractures intersected are nearly horizontal or have moderate- to high-angle northwest or eastward dip azimuths. Heat-pulse flowmeter logs obtained under nonpumping (ambient) and pumping conditions, together with other geophysical logs, delineated transmissive fracture zones in each borehole. Water-level and flowmeter data suggest the fractured-rock ground-water-flow system is interconnected. The 60 MHz directional borehole-radar logs delineated the location and orientation of several radar reflectors that did not intersect the projection of the borehole. A total of 53 faults intersected by the boreholes have mean orientation populations of N12°W, 66°W and N11°W, 70°E. A total of 77 transmissive fractures delineated using the heat-pulse flowmeter have mean orientations of N11°E, 14°SE (majority) and N23°E, 57°NW (minority). The transmissivity of the bedrock boreholes ranged from 0.7 to 870 feet squared (ft2) per day (0.07 to 81 metres squared (m2) per day).

  18. Novel method for estimation of the indoor-to-outdoor airborne radioactivity ratio following the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Tan, Yanliang; Ishikawa, Tetsuo; Janik, Miroslaw; Tokonami, Shinji; Hosoda, Masahiro; Sorimachi, Atsuyuki; Kearfott, Kimberlee

    2015-12-01

    The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan resulted in significant releases of fission products. While substantial data exist concerning outdoor air radioactivity following the accident, the resulting indoor radioactivity remains pure speculation without a proper method for estimating the ratio of the indoor to outdoor airborne radioactivity, termed the airborne sheltering factor (ASF). Lacking a meaningful value of the ASF, it is difficult to assess the inhalation doses to residents and evacuees even when outdoor radionuclide concentrations are available. A simple model was developed and the key parameters needed to estimate the ASF were obtained through data fitting of selected indoor and outdoor airborne radioactivity measurement data obtained following the accident at a single location. Using the new model with values of the air exchange rate, interior air volume, and the inner surface area of the dwellings, the ASF can be estimated for a variety of dwelling types. Assessment of the inhalation dose to individuals readily follows from the value of the ASF, the person's indoor occupancy factor, and the measured outdoor radioactivity concentration. PMID:26188529

  19. Novel method for estimation of the indoor-to-outdoor airborne radioactivity ratio following the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Tan, Yanliang; Ishikawa, Tetsuo; Janik, Miroslaw; Tokonami, Shinji; Hosoda, Masahiro; Sorimachi, Atsuyuki; Kearfott, Kimberlee

    2015-12-01

    The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan resulted in significant releases of fission products. While substantial data exist concerning outdoor air radioactivity following the accident, the resulting indoor radioactivity remains pure speculation without a proper method for estimating the ratio of the indoor to outdoor airborne radioactivity, termed the airborne sheltering factor (ASF). Lacking a meaningful value of the ASF, it is difficult to assess the inhalation doses to residents and evacuees even when outdoor radionuclide concentrations are available. A simple model was developed and the key parameters needed to estimate the ASF were obtained through data fitting of selected indoor and outdoor airborne radioactivity measurement data obtained following the accident at a single location. Using the new model with values of the air exchange rate, interior air volume, and the inner surface area of the dwellings, the ASF can be estimated for a variety of dwelling types. Assessment of the inhalation dose to individuals readily follows from the value of the ASF, the person's indoor occupancy factor, and the measured outdoor radioactivity concentration.

  20. Demonstrations in Introductory Geophysics

    NASA Astrophysics Data System (ADS)

    Schramm, K. A.; Stein, S.; van der Lee, S.; Swafford, L.; Klosko, E.; Delaughter, J.; Wysession, M.

    2005-12-01

    Geophysical concepts are challenging to teach at introductory levels, because students need to understand both the underlying physics and its geological application. To address this, our introductory courses include class demonstrations and experiments to demonstrate underlying physical principles and their geological applications. Demonstrations and experiments have several advantages over computer simulations. First, computer simulations "work" even if the basic principle is wrong. In contrast, simple demonstrations show that a principle is physically correct, rather than a product of computer graphics. Second, many students are unfamiliar with once-standard experiments demonstrating ideas of classical physics used in geophysics. Demonstrations are chosen that we consider stimulating, relevant, inexpensive, and easy to conduct in a non-lab classroom. These come in several groups. Many deal with aspects of seismic waves, using springs, light beams, and other methods such as talking from outside the room to illustrate the frequency dependence of diffraction (hearing but not seeing around a corner). Others deal with heat and mass transfer, such as illustrating fractional crystallization with apple juice and the surface/volume effect in planetary evolution with ice. Plate motions are illustrated with paper cutouts showing effects like motion on transform faults and how the Euler vector geometry changes a plate boundary from spreading, to strike-slip, to convergence along the Pacific-North America boundary from the Gulf of California to Alaska. Radioactive decay is simulated by having the class rise and sit down as a result of coin flips (one tail versus two gives different decay rates and hence half lives). This sessions' goal of exchanging information about demonstrations is an excellent idea: some of ours are described on http://www.earth.nwu.edu/people/seth/202.

  1. Geophysical techniques in detection to river embankments - A case study: To locate sites of potential leaks using surface-wave and electrical methods

    USGS Publications Warehouse

    Chen, C.; Liu, J.; Xu, S.; Xia, J.; ,

    2004-01-01

    Geophysical technologies are very effective in environmental, engineering and groundwater applications. Parameters of delineating nature of near-surface materials such as compressional-wave velocity, shear-wave velocity can be obtained using shallow seismic methods. Electric methods are primary approaches for investigating groundwater and detecting leakage. Both of methods are applied to detect embankment in hope of obtaining evidences of the strength and moisture inside the body. A technological experiment has done for detecting and discovering the hidden troubles in the embankment of Yangtze River, Songzi, Hubei, China in 2003. Surface-wave and DC multi-channel array resistivity sounding techniques were used to detect hidden trouble inside and under dike like pipe-seeps. This paper discusses the exploration strategy and the effect of geological characteristics. A practical approach of combining seismic and electric resistivity measurements was applied to locate potential pipe-seeps in embankment in the experiment. The method presents a potential leak factor based on the shear-wave velocity and the resistivity of the medium to evaluate anomalies. An anomaly found in a segment of embankment detected was verified, where occurred a pipe-seep during the 98' flooding.

  2. The DIGISOIL multi-sensor system: from geophysical measurements to soil properties.

    NASA Astrophysics Data System (ADS)

    Grandjean, Gilles

    2010-05-01

    The purposes of the multidisciplinary DIGISOIL project are the integration and improvement of in situ and proximal measurement technologies for the assessment of soil properties and soil degradation indicators, going from the sensing technologies to their integration and their application in (digital) soil mapping (DSM). In order to assess and prevent soil degradation and to benefit from the different ecological, economical and historical functions of the soil in a sustainable way, high resolution and quantitative maps of soil properties are needed. The core objective of the project is to explore and exploit new capabilities of advanced geophysical technologies for answering this societal demand. To this aim, DIGISOIL addresses four issues covering technological, soil science and economic aspects: (i) the validation of geophysical (in situ, proximal and airborne) technologies and integrated pedo-geophysical inversion techniques (mechanistic data fusion) (ii) the relation between the geophysical parameters and the soil properties, (iii) the integration of the derived soil properties for mapping soil functions and soil threats, (iv) the pre-evaluation, standardisation and sub-industrialization of the proposed methodologies, including technical and economical studies related to the societal demand. With respect to these issues, the preliminary tasks of the DIGISOIL project were to develop, test and validate the most relevant geophysical technologies for mapping soil properties. The different field tests, realized at this time, allow focusing on technological suitable solutions for each of the identified methods: geoelectric, GPR, EMI, seismics, magnetic and hyperspectral. After data acquisition systems, sensor geometry, and advanced data processing techniques have been developed and validated, we present now the solutions for going from such data to soil properties maps.

  3. High temperature geophysical instrumentation

    SciTech Connect

    Hardee, H.C.

    1988-06-01

    The instrumentation development program was to proceed in parallel with scientific research and was driven by the needs of researchers. The development of these instruments has therefore included numerous geophysical field tests, many of which have resulted in the publication of scientific articles. This paper is a brief summary of some of the major geophysical instruments that have been developed and tested under the High Temperature Geophysics Program. These instruments are briefly described and references are given for further detailed information and for scientific papers that have resulted from the use of these instruments. 9 refs., 14 figs.

  4. Fiber optic geophysical sensors

    DOEpatents

    Homuth, E.F.

    1991-03-19

    A fiber optic geophysical sensor is described in which laser light is passed through a sensor interferometer in contact with a geophysical event, and a reference interferometer not in contact with the geophysical event but in the same general environment as the sensor interferometer. In one embodiment, a single tunable laser provides the laser light. In another embodiment, separate tunable lasers are used for the sensor and reference interferometers. The invention can find such uses as monitoring for earthquakes, and the weighing of objects. 2 figures.

  5. Electromagnetic geophysical observation with controlled source

    NASA Astrophysics Data System (ADS)

    Hachay, Olga; Khachay, Oleg

    2016-04-01

    In the paper the new theoretical and methodical approaches are examined for detailed investigations of the structure and state of the geological medium, and its behavior as a dynamic system in reaction to external man-made influences. To solve this problem it is necessary to use geophysical methods that have sufficient resolution and that are built on more complicated models than layered or layered-block models. One of these methods is the electromagnetic induction frequency-geometrical method with controlled sources. Here we consider new approaches using this method for monitoring rock shock media by means of natural experiments and interpretation of the practical results. That method can be used by oil production in mines, where the same events of non stability can occur. The key ideas of twenty first century geophysics from the point of view of geologist academician A.N. Dmitrievskiy [Dmitrievskiy, 2009] are as follows. "The geophysics of the twenty first century is an understanding that the Earth is a self-developing, self-supporting geo-cybernetic system, in which the role of the driving mechanism is played by the field gradients; the evolution of geological processes is a continuous chain of transformations and the interaction of geophysical fields in the litho- hydro- and atmosphere. The use of geophysical principles of a hierarchical quantum of geophysical space, non-linear effects, and the effects of reradiating geophysical fields will allow the creation of a new geophysics. The research, in which earlier only pure geophysical processes and technologies were considered, nowadays tends to include into consideration geophysical-chemical processes and technologies. This transformation will allow us to solve the problems of forecasting geo-objects and geo-processes in previously unavailable geological-technological conditions." The results obtained allow us to make the following conclusions, according to the key ideas of academician A.N. Dmitrievskiy: the rock

  6. Application of surface-geophysical methods to investigations of sand and gravel aquifers in the glaciated Northeastern United States

    USGS Publications Warehouse

    Haeni, F.P.

    1995-01-01

    Combined use of seismic-refraction, direct-current resistivity, very-low-frequency terrain-resistivity, and inductive terrain-conductivity methods were demonstrated at sites in Connecticut, New York, and Maine. Although no single method can define both the hydrogeologic boundaries and general grain-size characteristics of sand and gravel aquifers, a combination of these methods can. Comparisons of measured electrical properties of aquifers with logs of test holes and wells indicate that, for a given conductivity of ground water, the bulk electrical resistivity of aquifers in the glaciated Northeast increases with grain size.

  7. Calibration and Confirmation in Geophysical Models

    NASA Astrophysics Data System (ADS)

    Werndl, Charlotte

    2016-04-01

    For policy decisions the best geophysical models are needed. To evaluate geophysical models, it is essential that the best available methods for confirmation are used. A hotly debated issue on confirmation in climate science (as well as in philosophy) is the requirement of use-novelty (i.e. that data can only confirm models if they have not already been used before. This talk investigates the issue of use-novelty and double-counting for geophysical models. We will see that the conclusions depend on the framework of confirmation and that it is not clear that use-novelty is a valid requirement and that double-counting is illegitimate.

  8. A global method for identifying dependences between helio-geophysical and biological series by filtering the precedents (outliers)

    NASA Astrophysics Data System (ADS)

    Ozheredov, V. A.; Breus, T. K.; Gurfinkel, Yu. I.; Matveeva, T. A.

    2014-12-01

    A new approach to finding the dependence between heliophysical and meteorological factors and physiological parameters is considered that is based on the preliminary filtering of precedents (outliers). The sought-after dependence is masked by extraneous influences which cannot be taken into account. Therefore, the typically calculated correlation between the external-influence ( x) and physiology ( y) parameters is extremely low and does not allow their interdependence to be conclusively proved. A robust method for removing the precedents (outliers) from the database is proposed that is based on the intelligent sorting of the polynomial curves of possible dependences y( x), followed by filtering out the precedents which are far away from y( x) and optimizing the coefficient of nonlinear correlation between the regular, i.e., remaining, precedents. This optimization problem is shown to be a search for a maximum in the absence of the concept of gradient and requires the use of a genetic algorithm based on the Gray code. The relationships between the various medical and biological parameters and characteristics of the space and terrestrial weather are obtained and verified using the cross-validation method. It is proven that, by filtering out no more than 20% of precedents, it is possible to obtain a nonlinear correlation coefficient of no less than 0.5. A juxtaposition of the proposed method for filtering precedents (outliers) and the least-square method (LSM) for determining the optimal polynomial using multiple independent tests (Monte Carlo method) of models, which are as close as possible to real dependences, has shown that the LSM determination loses much in comparison to the proposed method.

  9. Practical example for use of the supervised vicarious calibration (SVC) method on multisource hyperspectral imagery data - ValCalHyp airborne hyperspectral campaign under the EUFAR framework

    NASA Astrophysics Data System (ADS)

    Brook, A.; Ben Dor, E.

    2014-09-01

    A novel approach for radiometric calibration and atmospheric correction of airborne hyperspectral (HRS) data, termed supervised vicarious calibration (SVC) was proposed by Brook and Ben-Dor in 2010. The present study was aimed at validating this SVC approach by simultaneously using several different airborne HSR sensors that acquired HSR data over several selected sites at the same time. The general goal of this study was to apply a cross-calibration approach to examine the capability and stability of the SVC method and to examine its validity. This paper reports the result of the multi sensors campaign took place over Salon de Provenance, France on behalf of the ValCalHyp project took place in 2011. The SVC method enabled the rectification of the radiometric drift of each sensor and improves their performance significantly. The flight direction of the SVC targets was found to be a critical issue for such correction and recommendations have been set for future utilization of this novel method. The results of the SVC method were examined by comparing ground-truth spectra of several selected validation targets with the image spectra as well as by comparing the classified water quality images generated from all sensors over selected water bodies.

  10. DOMAIN DECOMPOSITION METHOD APPLIED TO A FLOW PROBLEM Norberto C. Vera Guzmán Institute of Geophysics, UNAM

    NASA Astrophysics Data System (ADS)

    Vera, N. C.; GMMC

    2013-05-01

    In this paper we present the results of macrohybrid mixed Darcian flow in porous media in a general three-dimensional domain. The global problem is solved as a set of local subproblems which are posed using a domain decomposition method. Unknown fields of local problems, velocity and pressure are approximated using mixed finite elements. For this application, a general three-dimensional domain is considered which is discretized using tetrahedra. The discrete domain is decomposed into subdomains and reformulated the original problem as a set of subproblems, communicated through their interfaces. To solve this set of subproblems, we use finite element mixed and parallel computing. The parallelization of a problem using this methodology can, in principle, to fully exploit a computer equipment and also provides results in less time, two very important elements in modeling. Referencias G.Alduncin and N.Vera-Guzmán Parallel proximal-point algorithms for mixed _nite element models of _ow in the subsurface, Commun. Numer. Meth. Engng 2004; 20:83-104 (DOI: 10.1002/cnm.647) Z. Chen, G.Huan and Y. Ma Computational Methods for Multiphase Flows in Porous Media, SIAM, Society for Industrial and Applied Mathematics, Philadelphia, 2006. A. Quarteroni and A. Valli, Numerical Approximation of Partial Differential Equations, Springer-Verlag, Berlin, 1994. Brezzi F, Fortin M. Mixed and Hybrid Finite Element Methods. Springer: New York, 1991.

  11. Geophysical Characterization of the Quaternary-Cretaceous Contact Using Surface Resistivity Methods in Franklin and Webster Counties, South-Central Nebraska

    USGS Publications Warehouse

    Teeple, Andrew P.; Kress, Wade H.; Cannia, James C.; Ball, Lyndsay B.

    2009-01-01

    To help manage and understand the Platte River system in Nebraska, the Platte River Cooperative Hydrology Study (COHYST), a group of state and local governmental agencies, developed a regional ground-water model. The southern boundary of this model lies along the Republican River, where an area with insufficient geologic data immediately north of the Republican River led to problems in the conceptualization of the simulated flow system and to potential problems with calibration of the simulation. Geologic descriptions from a group of test holes drilled in south-central Nebraska during 2001 and 2002 indicated a possible hydrologic disconnection between the Quaternary-age alluvial deposits in the uplands and those in the Republican River lowland. This disconnection was observed near a topographic high in the Cretaceous-age Niobrara Formation, which is the local bedrock. In 2003, the U.S. Geological Survey, in cooperation with the COHYST, collected surface geophysical data near these test holes to better define this discontinuity. Two-dimensional imaging methods for direct-current resistivity and capacitively coupled resistivity were used to define the subsurface distribution of resistivity along several county roads near Riverton and Inavale, Nebraska. The relation between the subsurface distribution of resistivity and geology was defined by comparing existing geologic descriptions of test holes to surface-geophysical resistivity data along two profiles and using the information gained from these comparisons to interpret the remaining four profiles. In all of the resistivity profile sections, there was generally a three-layer subsurface interpretation, with a resistor located between two conductors. Further comparison of geologic data with the geophysical data and with surficial features was used to identify a topographic high in the Niobrara Formation near the Franklin Canal which was coincident with a resistivity high. Electrical properties of the Niobrara

  12. Mutagenicity of airborne particles.

    PubMed

    Chrisp, C E; Fisher, G L

    1980-09-01

    The physical and chemical properties of airborne particles are important for the interpretation of their potential biologic significance as genotoxic hazards. For polydisperse particle size distributions, the smallest, most respirable particles are generally the most mutagenic. Particulate collection for testing purposes should be designed to reduce artifact formation and allow condensation of mutagenic compounds. Other critical factors such as UV irradiation, wind direction, chemical reactivity, humidity, sample storage, and temperature of combustion are important. Application of chemical extraction methods and subsequent class fractionation techniques influence the observed mutagenic activity. Particles from urban air, coal fly ash, automobile and diesel exhaust, agricultural burning and welding fumes contain primarily direct-acting mutagens. Cigarette smoke condensate, smoke from charred meat and protein pyrolysates, kerosene soot and cigarette smoke condensates contain primarily mutagens which require metabolic activation. Fractionation coupled with mutagenicity testing indicates that the most potent mutagens are found in the acidic fractions of urban air, coal fly ash, and automobile diesel exhaust, whereas mutagens in rice straw smoke and cigarette smoke condensate are found primarily in the basic fractions. The interaction of the many chemical compounds in complex mixtures from airborne particles is likely to be important in determining mutagenic or comutagenic potentials. Because the mode of exposure is generally frequent and prolonged, the presence of tumor-promoting agents in complex mixtures may be a major factor in evaluation of the carcinogenic potential of airborne particles.

  13. Evaluation of descriptive and non-intrusive geophysical methods for the identification of saturation area dynamics and their controls

    NASA Astrophysics Data System (ADS)

    Steenhuis, T. S.; Dahlke, H. E.; Harpold, A. A.

    2006-12-01

    In the Catskill Mountains of New York State runoff is most commonly generated from groundwater seeps, causing parts of the landscape to saturate. Groundwater seeps and frequently saturated near stream areas are important source waters for streams, but can also be contaminant-contributing areas in agricultural fields. Knowledge of the landscape position of these saturation areas, the spatial/temporal evolution of runoff generation and the connectivity to surface water bodies are important parameters to consider. Many water quality models and risk assessment techniques should rely on these principles when assessing non-point source pollution in agricultural watersheds. However, there is little research that has comprehensively studied the spatial/temporal dynamics of these saturated areas and provides methods that meet the present needs in hydrology and hydrological modelling applications. To characterize the spatial extent of saturated areas a study was conducted on a 2.44 ha hillslope in the Town Brook watershed in the Catskill Mountains. Various non-intrusive methods were used consisting of vegetation surveys, GPS mapping and electromagnetic induction (EMI) and compared to existing information obtained from ground water table measurements and remotely sensed data. To better understand the location of the saturated area we characterized the soil profile with Ground Penetrating Radar (GPR) and Geoseismic surveys. The non-intrusive methods could not agree with the observed patterns of the saturated areas nor with a simple distributed model that used only topography and low-resolution soil information. For a better characterization of these areas additional information about soil characteristics and preferential flow paths was needed. The latter could be obtained with the Geoseismic and Ground Penetrating Radar. These instruments were capable of measuring the local depth to the shallow hard pan and the presence of natural pipes that carried large amounts of water via

  14. Geophysics, Remote Sensing, and the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Integrated Field Exercise 2014

    NASA Astrophysics Data System (ADS)

    Sussman, A. J.; Macleod, G.; Labak, P.; Malich, G.; Rowlands, A. P.; Craven, J.; Sweeney, J. J.; Chiappini, M.; Tuckwell, G.; Sankey, P.

    2015-12-01

    The Integrated Field Exercise of 2014 (IFE14) was an event held in the Hashemite Kingdom of Jordan (with concurrent activities in Austria) that tested the operational and technical capabilities of an on-site inspection (OSI) within the CTBT verification regime. During an OSI, up to 40 international inspectors will search an area for evidence of a nuclear explosion. Over 250 experts from ~50 countries were involved in IFE14 (the largest simulation of a real OSI to date) and worked from a number of different directions, such as the Exercise Management and Control Teams (which executed the scenario in which the exercise was played) and those participants performing as members of the Inspection Team (IT). One of the main objectives of IFE14 was to test and integrate Treaty allowed inspection techniques, including a number of geophysical and remote sensing methods. In order to develop a scenario in which the simulated exercise could be carried out, suites of physical features in the IFE14 inspection area were designed and engineered by the Scenario Task Force (STF) that the IT could detect by applying the geophysical and remote sensing inspection technologies, in addition to other techniques allowed by the CTBT. For example, in preparation for IFE14, the STF modeled a seismic triggering event that was provided to the IT to prompt them to detect and localize aftershocks in the vicinity of a possible explosion. Similarly, the STF planted shallow targets such as borehole casings and pipes for detection using other geophysical methods. In addition, airborne technologies, which included multi-spectral imaging, were deployed such that the IT could identify freshly exposed surfaces, imported materials, and other areas that had been subject to modification. This presentation will introduce the CTBT and OSI, explain the IFE14 in terms of the goals specific to geophysical and remote sensing methods, and show how both the preparation for and execution of IFE14 meet those goals.

  15. Geoinformatic and geophysical methods for evaluation of deposition and reworking of sediments with contaminants in floodplain of the Ploucnice River, Czech Republic

    NASA Astrophysics Data System (ADS)

    Elznicova, Jitka; Matys Grygar, Tomas; Kiss, Timea; Babek, Ondrej; Popelka, Jan; Plotnarek, Lukas; Tumova, Stepanka; Majerova, Lucie; Hosek, Michal

    2014-05-01

    Complex study for the deposition and remobilization of pollutants in floodplain of the Ploucnice River requires geoinformatic, geomorphologic, geophysical and geochemical knowledge. Geoinformatic tools are usable in several science disciplines. Photogrammetric methods are a big tool for land-use change development and digital surface model (DSM) reconstruction. The historical photographs from 1938 till 1994 were orthorectified using ERDAS 2013 LPS software. Historical and actual orthophotos were used to study the channel migration of the Ploucnice River and lateral shifts of the channel in the last 70 years. Historical digital surfer model, which is reconstructed from historical orthophotos with 60% overlaps, were used for 3D visualisation of historical landscape and shows land-use changes. Accurate digital elevation model (DEM) from laser scanning dataset was created for geomorphological analysis. Topography was analysed with GIS methods and the geomorphologic interpretation was then performed. The subsurface architecture of the floodplain and distribution of the sediment bodies were studied using electrical resistivity tomography (ERT). The Wenner-Schlumberger method with 104 electrodes in a single array was used. An inverse model resistivity section was produced from the apparent resistivity pseudosection by the least-square inversion method using RES2DINV software (Geotomo Software, Malaysia). The contamination of the floodplain was analysed with both field and laboratory instruments. The portable gamma-spectrometer DISA 400A was used for acquisition of the total surface gamma activity in field. Several hundreds of soil samples (from drill cores) and recent flood deposits (after 2013 flood) were analysed by laboratory X-ray fluorescence spectrometer to describe deposition and remobilization of pollutants in floodplain, of which most important are Ba, Ni, Pb, U and Zn. Geostatistical analysis was used for creation of a statistically valid prediction surface. The

  16. Polarimetric Remote Sensing of Geophysical Medium Structures

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Yueh, S. H.; Kwok, R.; Nguyen, D. T.

    1993-01-01

    Polarimetric remote sensing of structures in geophysical media is studied in this paper based on their symmetry properties. Orientations of spheroidal scatterers described by spherical, uniform, planophile, plagiothile, erectophile, and extremophile distributions are considered to derive their polarimetric backscattering characteristics. These distributions can be identified from the observed scattering coefficients by comparison with theoretical symmetry calculations. A new parameter is defined to study scattering structures in geophysical media. Experimental observations from polarimetric data acquired by the Jet Propulsion Laboratory airborne synthetic aperture radar over forests, sea ice, and sea surface are presented to illustrate the use of symmetry properties. For forests, the coniferous forest in Mount Shasta area and mixed forests neir Presque Isle show evidence of the centrical symmetry at C band. In sea ice from the Beaufort Sea, multiyear sea ice has a cross-polarized ratio e close to e(sub 0), calculated from symmetry, due to the randomness in the scattering structure. For first-year sea ice, e is much smaller than e(sub 0) as a result of preferential alignment of the columnar structure of the ice. From polarimetric data of a sea surface in the Bering sea, it is observed that e and e(sub 0) are increasing with incident angle and e is greater than e(sub 0) at L band because of the directional feature of sea surface waves. Use of symmetry properties of geophysical media for polarimetric radar calibration is also suggested.

  17. Polarimetric remote sensing of geophysical medium structures

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.; Yueh, S. H.; Kwok, R.; Nguyen, D. T.

    1993-11-01

    Polarimetric remote sensing of structures in geophysical media is studied in this paper based on their symmetry properties. Orientations of spheroidal scatterers described by spherical, uniform, planophile, plagiothile, erectophile, and extremophile distributions are considered to derive their polarimetric backscattering characteristics. These distributions can be identified from the observed scattering coefficients by comparison with theoretical symmetry calculations. A new parameter is defined to study scattering structures in geophysical media. Experimental observations from polarimetric data acquired by the Jet Propulsion Laboratory airborne synthetic aperture radar over forests, sea ice, and sea surface are presented to illustrate the use of symmetry properties. For forests, the coniferous forest in Mount Shasta area and mixed forests near Presque Isle show evidence of the centrical symmetry at C band. In sea ice from the Beaufort Sea, multiyear sea ice has a cross-polarized ratio e close to e0, calculated from symmetry, due to the randomness in the scattering structure. For first-year sea ice, e is much smaller than e0 as a result of preferential alignment of the columnar structure of the ice. From polarimetric data of a sea surface in the Bering sea, it is observed that e and e0 are increasing with incident angle and e is greater than e0 at L band because of the directional feature of sea surface waves. Use of symmetry properties of geophysical media for polarimetric radar calibration is also suggested.

  18. SAGE (Summer of Applied Geophysical Experience): Learning Geophysics by Doing Geophysics

    NASA Astrophysics Data System (ADS)

    Jiracek, G. R.; Baldridge, W. S.; Biehler, S.; Braile, L. W.; Ferguson, J. F.; Gilpin, B. E.; Pellerin, L.

    2005-12-01

    SAGE, a field-based educational program in applied geophysical methods has been an REU site for 16 years and completed its 23rd year of operation in July 2005. SAGE teaches the major geophysical exploration methods (including seismics, gravity, magnetics, and electromagnetics) and applies them to the solution of specific local and regional geologic problems. These include delineating buried hazardous material; mapping archaeological sites; and studying the structure, tectonics, and water resources of the Rio Grande rift in New Mexico. Nearly 600 graduates, undergraduates, and professionals have attended SAGE since 1983. Since 1990 REU students have numbered 219 coming from dozens of different campuses. There have been 124 underrepresented REU students including 100 women, 14 Hispanics, 7 Native Americans, and 3 African Americans. Tracking of former REU students has revealed that 81% have gone on to graduate school. Keys to the success of SAGE are hands-on immersion in geophysics for one month and a partnership between academia, industry, and a federal laboratory. Successful approaches at SAGE include: 1) application of the latest equipment by all students; 2) continued updating of equipment, computers, and software by organizing universities and industry affiliates; 3) close ties with industry who provide supplemental instruction, furnish new equipment and software, and alert students to the current industry trends and job opportunities; 4) two-team, student data analysis structure that simultaneously addresses specific geophysical techniques and their integration; and 5) oral and written reports patterned after professional meetings and journals. An eight member, 'blue ribbon' advisory panel from academia, industry, and the federal government has been set up to maintain the vitality of SAGE by addressing such issues as funding, new faculty, organization, and vision. SAGE is open to students from any university (or organization) with backgrounds including

  19. A Field Evaluation of Airborne Techniques for Detection of Unexploded Ordnance

    SciTech Connect

    Bell, D.; Doll, W.E.; Hamlett, P.; Holladay, J.S.; Nyquist, J.E.; Smyre, J.; Gamey, T.J.

    1999-03-14

    US Defense Department estimates indicate that as many as 11 million acres of government land in the U. S. may contain unexploded ordnance (UXO), with the cost of identifying and disposing of this material estimated at nearly $500 billion. The size and character of the ordnance, types of interference, vegetation, geology, and topography vary from site to site. Because of size or composition, some ordnance is difficult to detect with any geophysical method, even under favorable soil and cultural interference conditions. For some sites, airborne methods may provide the most time and cost effective means for detection of UXO. Airborne methods offer lower risk to field crews from proximity to unstable ordnance, and less disturbance of sites that maybe environmentally sensitive. Data were acquired over a test site at Edwards AFB, CA using airborne magnetic, electromagnetic, multispectral and thermal sensors. Survey areas included sites where trenches might occur, and a test site in which we placed deactivated ordnance, ranging in size from small ''bomblets'' to large bombs. Magnetic data were then acquired with the Aerodat HM-3 system, which consists of three cesium magnetometers within booms extending to the front and sides of the helicopter, and mounted such that the helicopter can be flown within 3m of the surface. Electromagnetic data were acquired with an Aerodat 5 frequency coplanar induction system deployed as a sling load from a helicopter, with a sensor altitude of 15m. Surface data, acquired at selected sites, provide a comparison with airborne data. Multispectral and thermal data were acquired with a Daedelus AADS 1268 system. Preliminary analysis of the test data demonstrate the value of airborne systems for UXO detection and provide insight into improvements that might make the systems even more effective.

  20. Sensitivity analysis and application in exploration geophysics

    NASA Astrophysics Data System (ADS)

    Tang, R.

    2013-12-01

    In exploration geophysics, the usual way of dealing with geophysical data is to form an Earth model describing underground structure in the area of investigation. The resolved model, however, is based on the inversion of survey data which is unavoidable contaminated by various noises and is sampled in a limited number of observation sites. Furthermore, due to the inherent non-unique weakness of inverse geophysical problem, the result is ambiguous. And it is not clear that which part of model features is well-resolved by the data. Therefore the interpretation of the result is intractable. We applied a sensitivity analysis to address this problem in magnetotelluric(MT). The sensitivity, also named Jacobian matrix or the sensitivity matrix, is comprised of the partial derivatives of the data with respect to the model parameters. In practical inversion, the matrix can be calculated by direct modeling of the theoretical response for the given model perturbation, or by the application of perturbation approach and reciprocity theory. We now acquired visualized sensitivity plot by calculating the sensitivity matrix and the solution is therefore under investigation that the less-resolved part is indicated and should not be considered in interpretation, while the well-resolved parameters can relatively be convincing. The sensitivity analysis is hereby a necessary and helpful tool for increasing the reliability of inverse models. Another main problem of exploration geophysics is about the design strategies of joint geophysical survey, i.e. gravity, magnetic & electromagnetic method. Since geophysical methods are based on the linear or nonlinear relationship between observed data and subsurface parameters, an appropriate design scheme which provides maximum information content within a restricted budget is quite difficult. Here we firstly studied sensitivity of different geophysical methods by mapping the spatial distribution of different survey sensitivity with respect to the

  1. Measuring Groundwater Storage Potential in Mountain Meadows using Geophysical Methods at Red Clover Meadow Complex, Sierra Nevada, CA

    NASA Astrophysics Data System (ADS)

    Covey, J.; Cornwell, K.

    2014-12-01

    ABSTRACT The Dotta Canyon meadow, located in the Red Clover Meadow complex, upper Feather River Watershed, Plumas County, California, was studied to measure sediment volume and groundwater storage capacity in this mountain meadow environment. Groundwater resources in mountain meadows play an important role in providing baseflow to local stream systems during dry summer months. Degraded meadows reduce baseflow contributions to local streams throughout the year impacting the local flora and fauna and water resources downstream. Groundwater storage potential of meadows is a function of the total volume of meadow sediments, the types of sediment present and the effective porosity of those materials. Assessing these properties in meadows is difficult though as meadow environments are commonly sensitive to investigative disturbances like drill rigs and backhoes. We applied seismic refraction techniques to measure the thickness of meadow sediments in the 8.3 km2 Dotta Canyon. Specifically we conducted 42 seismic surveys, utilizing forward and reverse profiles to create a depth to bedrock isopach map of the Dotta Canyon meadow. Using ArcGIS software, aerial photographs and field GPS data to measure and calculate the meadow area and limited hand augering, we were able to calculate the volume of sediment in the meadow to be about 2.5E7 cubic meters. Hand augering in the meadow produced a record of meadow stratigraphy and helped determine appropriate locations for the collection of representative core samples. Representative cores were processed for effective porosity using the water porosimetry method. A mean effective porosity of 38%.was applied to volumetric calculations with results suggesting a groundwater storage capacity of 9.4E6 cubic meters.

  2. Suitability aero-geophysical methods for generating conceptual soil maps and their use in the modeling of process-related susceptibility maps

    NASA Astrophysics Data System (ADS)

    Tilch, Nils; Römer, Alexander; Jochum, Birgit; Schattauer, Ingrid

    2014-05-01

    . Previous studies show that, especially with radiometric measurements, the two-dimensional spatial variability of the nature of the process-relevant soil, close to the surface can be determined. In addition, the electromagnetic measurements are more important to obtain three-dimensional information of the deeper geological conditions and to improve the area-specific geological knowledge and understanding. The validation of these measurements is done with terrestrial geoelectrical measurements. So both aspects, radiometric and electromagnetic measurements, are important and subsequently, interpretation of the geophysical results can be used as the parameter maps in the modeling of more realistic susceptibility maps with respect to various processes. Within this presentation, results of geophysical measurements, the outcome and the derived parameter maps, as well as first process-oriented susceptibility maps in terms of gravitational soil mass movements will be presented. As an example results which were obtained with a heuristic method in an area in Vorarlberg (Western Austria) will be shown. References: Schwarz, L. & Tilch, N. (2011): Why are good process data so important for the modelling of landslide susceptibility maps?- EGU-Postersession "Landslide hazard and risk assessment, and landslide management" (NH 3.6), Vienna. [http://www.geologie.ac.at/fileadmin/user_upload/dokumente/pdf/poster/poster_2011_egu_schwarz_tilch_1.pdf] Tilch, N. & Schwarz, L. (2011): Spatial and scale-dependent variability in data quality and their influence on susceptibility maps for gravitational mass movements in soil, modelled by heuristic method.- EGU-Postersession "Landslide hazard and risk assessment, and landslide management" (NH 3.6); Vienna. [http://www.geologie.ac.at/fileadmin/user_upload/dokumente/pdf/poster/poster_2011_egu_tilch_schwarz.pdf

  3. Ground-Truth On The CSUEB Campus: Results From Integrating Geophysical, Geological And Geospatial Methods And Fault Trench Studies.

    NASA Astrophysics Data System (ADS)

    Abimbola, A.; Strayer, L. M.; McEvilly, A.

    2015-12-01

    A major (>M6) earthquake on the Hayward fault would be catastrophic, resulting in wide-ranging structural damage and potential loss of life. California State University, East Bay (CSUEB), in Hayward lies within the Hayward fault zone and is home to student residents. The campus is bound to the west by the Hayward and on the east by Chabot (CF) fault and is pervasively cut by anastomosing secondary splay faults. In June 2015 three exploratory trenches were opened on CSUEB campus to evaluate faulting within the proposed construction area of new student housing. Previous work by Dibblee found minor faulting in this area that we consider to be splays of the CF. We took the opportunity to conduct an active seismic survey, coincident with two of these three trenches. The purpose of our survey was to compare the results of these two methods, to further assess seismic hazard on campus, and to contribute to the ongoing effort to create a 3D model of the campus area. P-waves were generated by plate and 3.5kg sledgehammer, recorded on a 48-channel single component array for P-wave tomography and multichannel analysis of surface waves (MASW). Line 1 was 141m long with 3m receiver spacing and 9m shot spacing, and Line 2 was 188m long with 4m receivers spacing and 12m spacing. Initial P-wave tomography models show two velocity structures. To a depth of 25m, velocities ranged from 750-3000 m/s. At depths below 25m, we recorded P-wave velocities up to 6500 m/s, flanked by lower velocities, suggesting a bedrock unit bound by tectonically sheared material. Trench results indicate that faults and shears are indeed present in the top 2m. Additional near-surface seismic surveys are planned for the fall of 2015 to extend the trace of these faults, as they appear to cut across the entire campus. Furthermore, additional analysis of current and future seismic surveys will provide data on strong ground motion and offer insight into seismic hazards on the CSUEB campus. These new data will be

  4. The airborne infrared scanner as a geophysical research tool

    USGS Publications Warehouse

    Friedman, Jules D.

    1970-01-01

    The infrared scanner is proving to be an effective anomaly-mapping tool, albeit one which depicts surface emission directly and heat mass transfer from depths only indirectly and at a threshold level 50 to 100 times the normal conductive heat flow of the earth. Moreover, successive terrain observations are affected by time-dependent variables such as the diurnal and seasonal warming and cooling cycle of a point on the earth's surface. In planning precise air borne surveys of radiant flux from the earth's surface, account must be taken of background noise created by variations in micrometeorological factors and emissivity of surface materials, as well as the diurnal temperature cycle. The effect of the diurnal cycle may be minimized by planning predawn aerial surveys. In fact, the diurnal change is very small for most water bodies and the emissivity factor for water (e) =~ 1 so a minimum background noise is characteristic of scanner records of calm water surfaces.

  5. Airborne geophysical study in the pensacola mountains of antarctica

    USGS Publications Warehouse

    Behrendt, John C.; Meister, L.; Henderson, J.R.

    1966-01-01

    A seismic reflection, gravity, and aeromagnetic reconnaissance was made in the Pensacola Mountains, Antarctica, during the 1965-66 austral summer. Prominent ice streams located between the Neptune and Patuxent Ranges and east of the Forrestal Range overlie channels in the rock surface 2000 meters below sea level which are probably of glacial origin. Seismic reflections show that the Filchner Ice Shelf is 1270 meters thick near its southern margin. Along the boundary between West and East Antarctica, Bouguer anomalies decrease from +60 milligals in West Antarctica to -80 milligals in East Antarctica. An abrupt change in crustal structure across this boundary is required to explain the 2 milligals per kilometer gradient. This may indicate a fault extending through the crust into the mantle. Aeromagnetic profiles delineate anomalies up to 1800 ?? associated with the basic stratiform intrusion which comprises the Dufek and Forrestal ranges. A probable minimum area of 9500 square kilometers is calculated for the intrusive body on the basis of the magnetic anomalies, making it one of the largest bodies of its type. The extension of this magnetic anomaly across a fault forming the north border of the Pensacola Mountains probably precludes transcurrent movement.

  6. Airborne geophysical study in the pensacola mountains of antarctica.

    PubMed

    Behrendt, J C; Meister, L; Henderson, J R

    1966-09-16

    A seismic reflection, gravity, and aeromagnetic reconnaissance was made in the Pensacola Mountains, Antarctica, during the 1965-66 austral summer. Prominent ice streams located between the Neptune and Patuxent Ranges and east of the Forrestal Range overlie channels in the rock surface 2000 meters below sea level which are probably of glacial origin. Seismic reflections show that the Filchner Ice Shelf is 1270 meters thick near its southern margin. Along the boundary between West and East Antarctica, Bouguer anomalies decrease from +60 milligals in West Antarctica to -80 milligals in East Antarctica. An abrupt change in crustal structure across this boundary is required to explainl the 2 milligals per kilometer gradient. This may indicate a fault extending through the crust into the mantle. Aeromagnetic profiles delineate anomalies up to 1800 gamma associated with the basic stratiform intrusion which comprises the Dufek and Forrestal ranges. A probable minimum area of 9500 square kilometers is calculated for the intrusive body on the basis of the magnetic anomalies, making it one of the largest bodies of its type. The extension of this magnetic anominaly across a fault forming the north border of the Pensacola Mountains probably precludes transcurrent movement.

  7. Near-Real-Time Geophysical and Biological Monitoring of Bioremediation Methods at a Uranium Mill Tailings Site in Rifle, Colorado

    NASA Astrophysics Data System (ADS)

    Tarrell, A. N.; Haas, A.; Revil, A.; Figueroa, L. A.; Rodriguez, D.; Smartgeo

    2010-12-01

    network deployed through monitoring wells in the experiment tank and the development of a machine learning classifier to integrate near-real-time data into reactive transport models. The data collected from this experiment will allow the determination as to whether reduction due to bacterial growth results in current increases, or whether other factors in the soil may account for the current. Additional information concerning the tipping points for geochemical changes in porosity and their effect on signals from the electrode-based microbial monitoring may also be observed. The results of this work will allow the creation of a new data set collected from a more comprehensive monitoring network and will allow stakeholders at a site to develop effective decision-making tools on the long-term management of the site. The additional data will also aid in the long-term prediction abilities of a reactive transport model for a given site. As in situ bioremediation offers a low cost alternative to ex situ treatment methods, the results of this work will help to both reduce cost at existing sites and enable treatment of sites that otherwise have no clear solution.

  8. Site characterization at the Rabbit Valley Geophysical Performance Evaluation Range

    SciTech Connect

    Koppenjan, S,; Martinez, M.

    1994-06-01

    The United States Department of Energy (US DOE) is developing a Geophysical Performance Evaluation Range (GPER) at Rabbit Valley located 30 miles west of Grand Junction, Colorado. The purpose of the range is to provide a test area for geophysical instruments and survey procedures. Assessment of equipment accuracy and resolution is accomplished through the use of static and dynamic physical models. These models include targets with fixed configurations and targets that can be re-configured to simulate specific specifications. Initial testing (1991) combined with the current tests at the Rabbit Valley GPER will establish baseline data and will provide performance criteria for the development of geophysical technologies and techniques. The US DOE`s Special Technologies Laboratory (STL) staff has conducted a Ground Penetrating Radar (GPR) survey of the site with its stepped FM-CW GPR. Additionally, STL contracted several other geophysical tests. These include an airborne GPR survey incorporating a ``chirped`` FM-CW GPR system and a magnetic survey with a surfaced-towed magnetometer array unit Ground-based and aerial video and still frame pictures were also acquired. STL compiled and analyzed all of the geophysical maps and created a site characterization database. This paper discusses the results of the multi-sensor geophysical studies performed at Rabbit Valley and the future plans for the site.

  9. INEL cold test pit demonstration of improvements in information derived from non-intrusive geophysical methods over buried waste sites. Phase 2, Final report

    SciTech Connect

    Not Available

    1994-04-29

    Under Contract between US DOE Idaho National Engineering Laboratory (INEL) and the Blackhawk Geosciences Division of Coleman Research Corporation (BGD-CRC), geophysical investigations were conducted to improve the detection of buried wastes. Site characterization is a costly and time consuming process with the most costly components being drilling, sampling, and chemical analysis of samples. There is a focused effort at US DOE and other agencies to investigate methodologies that reduce costs and shorten the time between characterization and clean-up. These methodologies take the form of employing non-invasive (geophysical) and minimal invasive (e.g., cone penetrometer driving) techniques of characterization, and implementing a near real-time, rational decision-making process (Expedited Site Characterization). Over the Cold Test Pit (CTP) at INEL, data were acquired with multiple sensors on a dense grid. Over the CTP the interpretations inferred from geophysical data are compared with the known placement of various waste forms in the pit. The geophysical sensors employed were magnetics, frequency and time domain electromagnetics, and ground penetrating radar. Also, because of the high data density acquired, filtering and other data processing and imaging techniques were tested. The conclusions derived from the geophysical surveys were that pit boundaries, berms between cells within the pit, and individual objects placed in the pit were best mapped by the new Geonics EM61 time domain EM metal detector. Part of the reason for the effectiveness of the time domain metal detector is that objects buried in the pit are dominantly metallic. Also, the utility of geophysical data is significantly enhanced by dimensional and 3-dimensional imaging formats. These images will particularly assist remediation engineers in visualizing buried wastes.

  10. Improving airborne strapdown vector gravimetry using stabilized horizontal components

    NASA Astrophysics Data System (ADS)

    Cai, Shaokun; Zhang, Kaidong; Wu, Meiping

    2013-11-01

    Integrating the deflections of the vertical along the flight line can yield geoid profiles which are valuable in the study of geodesy and geophysics, fortunately, the deflections can be measured directly by vector gravimetry. Airborne vector gravimetry using a Strapdown Inertial Navigation System and the Global Navigation Satellite System (SINS/GNSS) has shown promising results in previous studies. However, the quality of the SINS and GNSS is a major limitation; in particular, the attitude errors induced by the gyros will result in large measurement errors to the horizontal components of the gravity disturbance, and these measurement errors represent the behavior of low-frequency trend. An airborne vector gravimetry method used to remove the bias and low-frequency trends in the gravity disturbance estimated for each survey line has been developed. This method uses the horizontal components of the gravity disturbance computed from EGM2008 (Earth Gravitational Model 2008) as a reference. Firstly, the horizontal measurement results obtained from the gravimeter are divided into high- and low-frequency components according to the resolution of the EGM2008, and then, the bias and low-frequency trends of the low-frequency components are corrected using a linear fit to the EGM2008 reference data. Finally, the ultimate results can be acquired after combining the high-frequency components and the corrected low-frequency components. The data used was obtained from the SGA-WZ, which is the first strapdown airborne gravimeter developed in China. The results of this method are promising. The internal accuracy of the gravity disturbance's horizontal components for repeated survey lines exceeds 3.5 mGal, and the corresponding resolution is approximately 4.8 km based on 160-s data smoothing and an airplane averaging speed of approximately 216 km/h. After applying the WCF (Wavenumber Correlation Filter), the internal accuracy of the horizontal components exceeds 2 mGal. This can

  11. Evaluation of airborne thermal, magnetic, and electromagnetic characterization technologies

    SciTech Connect

    Josten, N.E.

    1992-03-01

    The identification of Buried Structures (IBS) or Aerial Surveillance Project was initiated by the US Department of Energy (DOE) Office of Technology Development to demonstrate airborne methods for locating and identifying buried waste and ordnance at the Idaho National Engineering Laboratory (INEL). Two technologies were demonstrated: (a) a thermal infrared imaging system built by Martin Marietta Missile Systems and (b) a magnetic and electromagnetic (EM) geophysical surveying system operated by EBASCO Environmental. The thermal system detects small differences in ground temperature caused by uneven heating and cooling of the ground by the sun. Waste materials on the ground can be detected when the temperature of the waste is different than the background temperature. The geophysical system uses conventional magnetic and EM sensors. These sensors detect disturbances caused by magnetic or conductive waste and naturally occurring magnetic or conductive features of subsurface soils and rock. Both systems are deployed by helicopter. Data were collected at four INEL sites. Tests at the Naval Ordnance Disposal Area (NODA) were made to evaluate capabilities for detecting ordnance on the ground surface. Tests at the Cold Simulated Waste Demonstration Pit were made to evaluate capabilities for detecting buried waste at a controlled site, where the location and depth of buried materials are known. Tests at the Subsurface Disposal Area and Stationary Low-Power Reactor-1 burial area were made to evaluate capabilities for characterizing hazardous waste at sites that are typical of DOE buried waste sites nationwide.

  12. Geophysical characterization of subsurface barriers

    SciTech Connect

    Borns, D.J.

    1995-08-01

    An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier.

  13. Quantifying groundwater exchange rates in a beach barrier lagoon using a radioisotopic tracer and geophysical methods: Younger Lagoon, Santa Cruz, CA

    NASA Astrophysics Data System (ADS)

    Richardson, C. M.; Swarzenski, P. W.; Johnson, C.

    2013-12-01

    Coastal lagoons are highly productive systems with a strong dependence on the physico-chemical regime of their surrounding environment. Groundwater interactions with the nearshore environment can drive ecosystem stability and productivity. Lagoons with restricted surface connectivity interact with coastal waters via subsurface flow paths that follow natural hydraulic gradients, producing a dynamic freshwater-saltwater mixing zone with submarine groundwater discharge (SGD) regions that are tidally influenced. Recent studies demonstrate the importance of SGD in maintaining nearshore ecology through a number of processes, including enhanced chemical loadings, focused biogeochemical transformations, and complex water mixing scenarios (Slomp and Van Cappellen, 2004 and Taniguchi et al., 2002). Groundwater discharge to the coastal ocean is often slow, diffuse and site-specific. Traditional methods used to evaluate SGD fluxes operate at varying scales and typically result in over or underestimates of SGD. Novel monitoring and evaluation methods are required in order to better understand how coastal aquifer systems influence multi-scalar water and nutrient budgets. Recently developed methods to determine fluid exchange rates include the use of select U- and Th-series radionuclides, multi-channel resistivity imaging, as well as the integration of temperature data and 1-D analytical modeling. Groundwater fluxes were examined in a coastal lagoon system to characterize the physics of subsurface fluid transport evidenced by visible seepage faces at low tide. Fluid exchange rates were quantified to determine the spatial and temporal variability of groundwater movement using thermal time series, water level data, and a coupled radiotracer-geophysical method. Our investigation of subsurface characteristics and groundwater fluxes using both traditional and newly-developed methods indicated that seasonal water inputs and tidal controls on water table elevation significantly

  14. Probing The Buried Remains of The Todos los Santos, City of San Salvador in Hoping Island with Shallow Subsurface Geophysics Method

    NASA Astrophysics Data System (ADS)

    Tsai, Yi-fan; Chang, Pin-yu; Eugenio Borao Mateo, José

    2013-04-01

    The study in ancient sites with GPR is widely documented over several decades. This non-invasive geophysical method provides a rapid measure for anthropogenic objects and therefore serves as a guide for possible excavation for the next stage of archaeological surveys. City of San Salvador, which is a Dutch colonial city consisted of fortress, hospitals and churches in 17 century, is located in the Hoping Island in Keelung, Taiwan. The fortress and its affiliated structures were abandoned and left collapsing since the mid-17th century. Some relics of the fortress wall were still remained until the early 20th century but the fast development projects in the island has caused the relics demolished or buried under building or road pavements. Many wells and bones have been found around the area belong to over three hundred years ago. As a consequence, the government initiated a new excavation project at the parking lot where the ancient convent of Todos los Santos is believed since 2011 in order to find the remains of the convent in city of San Salvador. Meanwhile we have surveyed with GPR to help guiding the excavation location. In this case, we surveyed with wide-angle-refraction/reflection (WARR) of GPR as well as common-offset array, to compensate the defect of traditional common-offset of lack of longitudinal resolution with velocity profile, and the combination of velocity profile and common-offset data helped distinguish the signals from other noises and further located the position of subsurface structures. After data analysis and numerical modeling of the buried materials, we have located the possible remains of walls of the convent or other structures around 0.9 to 1.3 meters in depth that can offer useful information to better plan the archaeological excavations.

  15. Geophysical monitoring using 3D joint inversion of multi-modal geophysical data with Gramian constraints

    NASA Astrophysics Data System (ADS)

    Zhdanov, M. S.; Gribenko, A.; Wilson, G. A.

    2012-12-01

    Geophysical monitoring of reservoir fluids and rock properties is relevant to oil and gas production, carbon sequestration, and enhanced geothermal systems. Different geophysical fields provide information about different physical properties of the earth. Multiple geophysical surveys spanning gravity, magnetic, electromagnetic, seismic, and thermal methods are often interpreted to infer geology from models of different physical properties. In many cases, the various geophysical data are complimentary, making it natural to consider a formal mathematical framework for their joint inversion to a shared earth model. We introduce a new approach to the 3D joint inversion of multiple geophysical datasets using Gramian spaces of model parameters and Gramian constraints, computed as determinants of the corresponding Gram matrices of the multimodal model parameters and/or their attributes. The basic underlying idea of this approach is that the Gramian provides a measure of correlation between the model parameters. By imposing an additional requirement of the minimum of the Gramian, we arrive at the solution of the joint multimodal inverse problem with the enhanced correlation between the different model parameters and/or their attributes. We demonstrate that this new approach is a generalized technique that can be applied to the simultaneous joint inversion of any number and combination of geophysical datasets. Our approach includes as special cases those extant methods based on correlations and/or structural constraints of different physical properties. We illustrate this approach by a model study of reservoir monitoring using different geophysical data.

  16. Airborne gravity measurement over sea-ice: The western Weddel Sea

    SciTech Connect

    Brozena, J.; Peters, M. ); LaBrecque, J.; Bell, R.; Raymond, C. )

    1990-10-01

    An airborne gravity study of the western Weddel Sea, east of the Antarctic Peninsula, has shown that floating pack-ice provides a useful radar altimetric reference surface for altitude and vertical acceleration corrections surface for alititude and vertical acceleration corrections to airborne gravimetry. Airborne gravimetry provides an important alternative to satellite altimetry for the sea-ice covered regions of the world since satellite alimeters are not designed or intended to provide accurate geoidal heights in areas where significant sea-ice is present within the radar footprint. Errors in radar corrected airborne gravimetry are primarily sensitive to the variations in the second derivative of the sea-ice reference surface in the frequency pass-band of interest. With the exception of imbedded icebergs the second derivative of the pack-ice surface closely approximates that of the mean sea-level surface at wavelengths > 10-20 km. With the airborne method the percentage of ice coverage, the mixture of first and multi-year ice and the existence of leads and pressure ridges prove to be unimportant in determining gravity anomalies at scales of geophysical and geodetic interest, provided that the ice is floating and not grounded. In the Weddell study an analysis of 85 crosstrack miss-ties distributed over 25 data tracks yields an rms error of 2.2 mGals. Significant structural anomalies including the continental shelf and offsets and lineations interpreted as fracture zones recording the early spreading directions within the Weddell Sea are observed in the gravity map.

  17. An Introduction to Geophysical Exploration: Third Edition

    NASA Astrophysics Data System (ADS)

    Tatham, Robert H.

    Finding a modern textbook that covers all aspects of exploration geophysics is difficult, but An Introduction to Geophysical Exploration certainly fills the bill. Appropriate for an introductory course addressing a range of techniques the book's breadth is demonstrated by comprehensive inclusion of non-seismic exploration methods. In fact, half of the book is devoted to non-seismic methods, providing students with a permanent reference to these infrequently applied exploration methods.This book came to my attention while I was ordering textbooks for a course in exploration geophysics only to find that the text of my choice was out of print. I quickly substituted An Introduction to Geophysical Exploration, and it has served the class well, including senior-level undergraduates and first-year graduate students in both soft-rock geology and geophysics. The material is comprehensive and well organized. The non-seismic topics include not only chapters on potential fields— one each on gravity and magnetic methods— but also chapters on electrical and electromagnetic methods, including ground-penetrating radar (GPR). Short chapters on radiometric surveying and borehole logging are also provided.

  18. Integration of geological, geochemical, and geophysical spatial data of the Cement oil field, Oklahoma, test site

    USGS Publications Warehouse

    Termain, Patricia A.; Donovan, Terrence J.; Chavez, Pat S.

    1980-01-01

    Measurement pertaining to geology, geochemistry, and geophysics of the Cement oil field, Oklahoma, test site were collected employing both airborne sensors and ground-based data collection. The measurements include: (1) airborne gamma-ray spectrometry (supplying bismuth 214, thalium 208, and potassium 40 gamma-ray intensities); (2) aeromagnetic survey data; (3) multi-frequency airborne resistivity survey data (supplying apparent electrical resistivity of near surface materials); (4) gravity data; (5) geological and topographic maps; and (6) image data from Landsat MSS and U-2 photography.

  19. Terrestrial Planet Geophysics

    NASA Astrophysics Data System (ADS)

    Phillips, R. J.

    2008-12-01

    Terrestrial planet geophysics beyond our home sphere had its start arguably in the early 1960s, with Keith Runcorn contending that the second-degree shape of the Moon is due to convection and Mariner 2 flying past Venus and detecting no planetary magnetic field. Within a decade, in situ surface geophysical measurements were carried out on the Moon with the Apollo program, portions of the lunar magnetic and gravity fields were mapped, and Jack Lorell and his colleagues at JPL were producing spherical harmonic gravity field models for Mars using tracking data from Mariner 9, the first spacecraft to orbit another planet. Moreover, Mariner 10 discovered a planetary magnetic field at Mercury, and a young Sean Solomon was using geological evidence of surface contraction to constrain the thermal evolution of the innermost planet. In situ geophysical experiments (such as seismic networks) were essentially never carried out after Apollo, although they were sometimes planned just beyond the believability horizon in planetary mission queues. Over the last three decades, the discipline of terrestrial planet geophysics has matured, making the most out of orbital magnetic and gravity field data, altimetric measurements of surface topography, and the integration of geochemical information. Powerful constraints are provided by tectonic and volcanic information gleaned from surface images, and the engagement of geologists in geophysical exercises is actually quite useful. Accompanying these endeavors, modeling techniques, largely adopted from the Earth Science community, have become increasingly sophisticated and have been greatly enhanced by the dramatic increase in computing power over the last two decades. The future looks bright with exciting new data sets emerging from the MESSENGER mission to Mercury, the promise of the GRAIL gravity mission to the Moon, and the re-emergence of Venus as a worthy target for exploration. Who knows? With the unflagging optimism and persistence

  20. Airborne agent concentration analysis

    DOEpatents

    Gelbard, Fred

    2004-02-03

    A method and system for inferring airborne contaminant concentrations in rooms without contaminant sensors, based on data collected by contaminant sensors in other rooms of a building, using known airflow interconnectivity data. The method solves a least squares problem that minimizes the difference between measured and predicted contaminant sensor concentrations with respect to an unknown contaminant release time. Solutions are constrained to providing non-negative initial contaminant concentrations in all rooms. The method can be used to identify a near-optimal distribution of sensors within the building, when then number of available sensors is less than the total number of rooms. This is achieved by having a system-sensor matrix that is non-singular, and by selecting that distribution which yields the lowest condition number of all the distributions considered. The method can predict one or more contaminant initial release points from the collected data.

  1. Resources for Computational Geophysics Courses

    NASA Astrophysics Data System (ADS)

    Keers, Henk; Rondenay, Stéphane; Harlap, Yaël.; Nordmo, Ivar

    2014-09-01

    An important skill that students in solid Earth physics need to acquire is the ability to write computer programs that can be used for the processing, analysis, and modeling of geophysical data and phenomena. Therefore, this skill (which we call "computational geophysics") is a core part of any undergraduate geophysics curriculum. In this Forum, we share our personal experience in teaching such a course.

  2. High-order Hybridized Discontinuous Galerkin (HDG) method for wave propagation simulation in complex geophysical media (elastic, acoustic and hydro-acoustic); an unifying framework to couple continuous Spectral Element and Discontinuous Galerkin Methods

    NASA Astrophysics Data System (ADS)

    Terrana, Sebastien; Vilotte, Jean-Pierre; Guillot, Laurent; Mariotti, Christian

    2015-04-01

    Today seismological observation systems combine broadband seismic receivers, hydrophones and micro-barometers antenna that provide complementary observations of source-radiated waves in heterogeneous and complex geophysical media. Exploiting these observations requires accurate and multi-physics - elastic, hydro-acoustic, infrasonic - wave simulation methods. A popular approach is the Spectral Element Method (SEM) (Chaljub et al, 2006) which is high-order accurate (low dispersion error), very flexible to parallelization and computationally attractive due to efficient sum factorization technique and diagonal mass matrix. However SEMs suffer from lack of flexibility in handling complex geometry and multi-physics wave propagation. High-order Discontinuous Galerkin Methods (DGMs), i.e. Dumbser et al (2006), Etienne et al. (2010), Wilcox et al (2010), are recent alternatives that can handle complex geometry, space-and-time adaptativity, and allow efficient multi-physics wave coupling at interfaces. However, DGMs are more memory demanding and less computationally attractive than SEMs, especially when explicit time stepping is used. We propose a new class of higher-order Hybridized Discontinuous Galerkin Spectral Elements (HDGSEM) methods for spatial discretization of wave equations, following the unifying framework for hybridization of Cockburn et al (2009) and Nguyen et al (2011), which allows for a single implementation of conforming and non-conforming SEMs. When used with energy conserving explicit time integration schemes, HDGSEM is flexible to handle complex geometry, computationally attractive and has significantly less degrees of freedom than classical DGMs, i.e., the only coupled unknowns are the single-valued numerical traces of the velocity field on the element's faces. The formulation can be extended to model fractional energy loss at interfaces between elastic, acoustic and hydro-acoustic media. Accuracy and performance of the HDGSEM are illustrated and

  3. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry.

    PubMed

    Kero, Ida Teresia; Jørgensen, Rikke Bramming

    2016-01-01

    The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPI(TM)), a Fast Mobility Particle Sizer (FMPS(TM)), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification.

  4. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry

    PubMed Central

    Kero, Ida Teresia; Jørgensen, Rikke Bramming

    2016-01-01

    The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPITM), a Fast Mobility Particle Sizer (FMPSTM), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification. PMID:27598180

  5. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry.

    PubMed

    Kero, Ida Teresia; Jørgensen, Rikke Bramming

    2016-01-01

    The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPI(TM)), a Fast Mobility Particle Sizer (FMPS(TM)), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification. PMID:27598180

  6. TESTING GROUND BASED GEOPHYSICAL TECHNIQUES TO REFINE ELECTROMAGNETIC SURVEYS NORTH OF THE 300 AREA HANFORD WASHINGTON

    SciTech Connect

    PETERSEN SW

    2010-12-02

    Airborne electromagnetic (AEM) surveys were flown during fiscal year (FY) 2008 within the 600 Area in an attempt to characterize the underlying subsurface and to aid in the closure and remediation design study goals for the 200-PO-1 Groundwater Operable Unit (OU). The rationale for using the AEM surveys was that airborne surveys can cover large areas rapidly at relatively low costs with minimal cultural impact, and observed geo-electrical anomalies could be correlated with important subsurface geologic and hydrogeologic features. Initial interpretation of the AEM surveys indicated a tenuous correlation with the underlying geology, from which several anomalous zones likely associated with channels/erosional features incised into the Ringold units were identified near the River Corridor. Preliminary modeling resulted in a slightly improved correlation but revealed that more information was required to constrain the modeling (SGW-39674, Airborne Electromagnetic Survey Report, 200-PO-1 Groundwater Operable Unit, 600 Area, Hanford Site). Both time-and frequency domain AEM surveys were collected with the densest coverage occurring adjacent to the Columbia River Corridor. Time domain surveys targeted deeper subsurface features (e.g., top-of-basalt) and were acquired using the HeliGEOTEM{reg_sign} system along north-south flight lines with a nominal 400 m (1,312 ft) spacing. The frequency domain RESOLVE system acquired electromagnetic (EM) data along tighter spaced (100 m [328 ft] and 200 m [656 ft]) north-south profiles in the eastern fifth of the 200-PO-1 Groundwater OU (immediately adjacent to the River Corridor). The overall goal of this study is to provide further quantification of the AEM survey results, using ground based geophysical methods, and to link results to the underlying geology and/or hydrogeology. Specific goals of this project are as follows: (1) Test ground based geophysical techniques for the efficacy in delineating underlying geology; (2) Use ground

  7. EXTENT AND KINEMATICS OF ASWA SHEAR ZONE IN UGANDA AND SOUTH SUDAN USING AIRBORNE GEOPHYSICAL AND REMOTE SENSING DATA. A. Katumwehe. 1, E. A. Atekwana. 1, M.G. Abdelsalam.1 1Oklahoma State University, Boone Pickens School of Geology, Stillwater, USA

    NASA Astrophysics Data System (ADS)

    katumwehe, A. B.; Atekwana, E. A.; Abdel Salam, M. G.

    2012-12-01

    The Aswa Shear zone (ASZ) is a fundamental Precambrian lithospheric structure playing an important role in the evolution of the Mesozoic South Sudan rifts, the propagation of the Cenozoic East African Rift System (EARS), the eruption of EARS shield volcanoes (Mt Kilimanjaro and Mt Elgon), re-organization of drainage systems (the White Nile), and the distribution of recent seismicity in South Sudan. Traces of the shear zone have been mapped extending in central and east Africa in a NW-SE direction from South Sudan in the northwest through Uganda and Tanzania to the southeast and possibly into Madagascar. Gondwana reconstructions suggest that the ASZ continues further southeast into south India. Nonetheless, the kinematics and extent of the ASZ have not been fully understood because of limited exposure. In areas where it is exposed the shear zone is expressed by narrow dominantly NW-trending outcrops. We use recently acquired high resolution airborne magnetic and radiometric data over Uganda integrated with 90 m spatial resolution Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) and 30 m spatial resolution Landsat Thematic Mapper (TM) spectral data to elucidate the kinematics and ascertain the significance of the ASZ in the development of the EARS and the tectonic architecture of east and central Africa. Vertical derivative, Euler deconvolution and analytical signal filters were applied to the total field magnetic data to image the shallow subsurface structures associated with the ASZ while upward continuation (5000 m) was applied to assess the ASZ depth continuity. We also used radiometric data to create ternary images while SRTM and Landsat TM data were used to map the surface expression of the shear zone. The geophysical data from Uganda suggest that the ASZ is characterised by a 50-60 km wide corridor of ductile deformation associated with NW-trending strike-slip shearing. It is dominated by three, equally-spaced and discrete sinistral strike

  8. Geophysical investigations in Jordan

    USGS Publications Warehouse

    Kovach, R.L.; Andreasen, G.E.; Gettings, M.E.; El-Kaysi, K.

    1990-01-01

    A number of geophysical investigations have been undertaken in the Hashemite Kingdom of Jordan to provide data for understanding the tectonic framework, the pattern of seismicity, earthquake hazards and geothermal resources of the country. Both the historical seismic record and the observed recent seismicity point to the dominance of the Dead Sea Rift as the main locus of seismic activity but significant branching trends and gaps in the seismicity pattern are also seen. A wide variety of focal plane solutions are observed emphasizing the complex pattern of fault activity in the vicinity of the rift zone. Geophysical investigations directed towards the geothermal assessment of the prominent thermal springs of Zerga Ma'in and Zara are not supportive of the presence of a crustal magmatic source. ?? 1990.

  9. Study of airborne science experiment management concepts for application to space shuttle, volume 2

    NASA Technical Reports Server (NTRS)

    Mulholland, D. R.; Reller, J. O., Jr.; Neel, C. B.; Haughney, L. C.

    1973-01-01

    Airborne research management and shuttle sortie planning at the Ames Research Center are reported. Topics discussed include: basic criteria and procedures for the formulation and approval of airborne missions; ASO management structure and procedures; experiment design, development, and testing aircraft characteristics and experiment interfaces; information handling for airborne science missions; mission documentation requirements; and airborne science methods and shuttle sortie planning.

  10. High-Order Hybridized Discontinuous Galerkin (HDG) Method for Wave Propagation Simulation in Complex Geophysical Media - Elastic, Acoustic and Hydro-Acoustic - an Unifying Framework to Couple Continuous Spectral Element and Discontinuous Galerkin Methods.

    NASA Astrophysics Data System (ADS)

    Sébastien, T.; Vilotte, J. P.; Guillot, L.; Mariotti, C.

    2014-12-01

    Today seismological observation systems combine broadband seismic receivers, hydrophones and micro-barometers antenna that provide complementary observations of source-radiated waves in heterogeneous and complex geophysical media. Exploiting these observations requires accurate and multi-physics - elastic, hydro-acoustic, infrasonic - wave simulation methods. A popular approach is the Spectral Element Method (SEM) (Chaljub et al, 2006) which is high-order accurate (low dispersion error), very flexible to parallelization and computationally attractive due to efficient sum factorization technique and diagonal mass matrix. However SEMs suffer from lack of flexibility in handling complex geometry and multi-physics wave propagation. High-order Discontinuous Galerkin Methods (DGMs), i.e. Dumbser et al (2006), Etienne et al. (2010), Wilcox et al (2010), are recent alternatives that can handle complex geometry, space-and-time adaptativity, and allow efficient multi-physics wave coupling at interfaces. However, DGMs are more memory demanding and less computationally attractive than SEMs, especially when explicit time stepping is used. We propose a new class of higher-order Hybridized Discontinuous Galerkin Spectral Elements (HDGSEM) methods for spatial discretization of wave equations, following the unifying framework for hybridization of Cockburn et al (2009) and Nguyen et al (2011), which allows for a single implementation of conforming and non-conforming SEMs. When used with energy conserving explicit time integration schemes, HDGSEM is flexible to handle complex geometry, computationally attractive and has significantly less degrees of freedom than classical DGMs, i.e., the only coupled unknowns are the single-valued numerical traces of the velocity field on the element's faces. The formulation can be extended to model fractional energy loss at interfaces between elastic, acoustic and hydro-acoustic media. Accuracy and performance of the HDGSEM are illustrated and

  11. Infrared airborne spectroradiometer survey results in the western Nevada area

    NASA Technical Reports Server (NTRS)

    Collins, W.; Chang, S. H.; Kuo, J. T.

    1982-01-01

    The Mark II airborne spectroradiometer system was flown over several geologic test sites in western Nevada. The infrared mineral absorption bands were observed and recorded for the first time using an airborne system with high spectral resolution in the 2.0 to 2.5 micron region. The data show that the hydrothermal alteration zone minerals, carbonates, and other minerals are clearly visible in the airborne survey mode. The finer spectral features that distinguish the various minerals with infrared bands are also clearly visible in the airborne survey data. Using specialized computer pattern recognition methods, it is possible to identify mineralogy and map alteration zones and lithologies by airborne spectroradiometer survey techniques.

  12. Groundwater contamination in the basement-complex area of Ile-Ife, southwestern Nigeria: A case study using the electrical-resistivity geophysical method

    NASA Astrophysics Data System (ADS)

    Adepelumi, A. A.; Ako, B. D.; Ajayi, T. R.

    2001-11-01

    Hydrogeoenvironmental studies were carried out at the sewage-disposal site of Obafemi Awolowo University campus, Ile-Ife, Nigeria. The objective of the survey was to determine the reliability of the electrical-resistivity method in mapping pollution plumes in a bedrock environment. Fifty stations were occupied with the ABEM SAS 300C Terrameter using the Wenner array. The electrical-resistivity data were interpreted by a computer-iteration technique. Water samples were collected at a depth of 5.0 m in 20 test pits and analyzed for quality. The concentrations of Cr, Cd, Pb, Zn, and Cu are moderately above the World Health Organization recommended guidelines. Plumes of contaminated water issuing from the sewage ponds were delineated. The geoelectric sections reveal four subsurface layers, with increasing depth, lateritic clay, clayey sand/sand, and weathered/fractured bedrock, and fresh bedrock. The deepest layers, 3 and 4, constitute the main aquifer, which has a thickness of 3.1-67.1 m. The distribution of the elements in the sewage effluent confirms a hydrological communication between the disposal ponds and groundwater. The groundwater is contaminated, as shown by sampling and the geophysical results. Thus, the results demonstrate the reliability of the direct-current electrical-resistivity geophysical method in sensing and mapping pollution plumes in a crystalline bedrock environment. Résumé. Des études géo-environnementales ont été réalisées sur le site d'épandages du campus universitaire d'Obafemi Awolowo, à Ile-Ife (Nigeria). L'objectif de ce travail était de déterminer la fiabilité de la méthode des résistivités électriques pour cartographier les panaches de pollution dans un environnement de socle. Cinquante stations ont été soumises à mesures au moyen d'un ABEM SAS 300C Terrameter en utilisant le dispositif de Wenner. Les données de résistivité électrique ont été interprétées au moyen d'une technique de calcul itérative. Des

  13. Groundwater contamination in the basement-complex area of Ile-Ife, southwestern Nigeria: A case study using the electrical-resistivity geophysical method

    NASA Astrophysics Data System (ADS)

    Adepelumi, A. A.; Ako, B. D.; Ajayi, T. R.

    2001-11-01

    Hydrogeoenvironmental studies were carried out at the sewage-disposal site of Obafemi Awolowo University campus, Ile-Ife, Nigeria. The objective of the survey was to determine the reliability of the electrical-resistivity method in mapping pollution plumes in a bedrock environment. Fifty stations were occupied with the ABEM SAS 300C Terrameter using the Wenner array. The electrical-resistivity data were interpreted by a computer-iteration technique. Water samples were collected at a depth of 5.0 m in 20 test pits and analyzed for quality. The concentrations of Cr, Cd, Pb, Zn, and Cu are moderately above the World Health Organization recommended guidelines. Plumes of contaminated water issuing from the sewage ponds were delineated. The geoelectric sections reveal four subsurface layers, with increasing depth, lateritic clay, clayey sand/sand, and weathered/fractured bedrock, and fresh bedrock. The deepest layers, 3 and 4, constitute the main aquifer, which has a thickness of 3.1-67.1 m. The distribution of the elements in the sewage effluent confirms a hydrological communication between the disposal ponds and groundwater. The groundwater is contaminated, as shown by sampling and the geophysical results. Thus, the results demonstrate the reliability of the direct-current electrical-resistivity geophysical method in sensing and mapping pollution plumes in a crystalline bedrock environment. Résumé. Des études géo-environnementales ont été réalisées sur le site d'épandages du campus universitaire d'Obafemi Awolowo, à Ile-Ife (Nigeria). L'objectif de ce travail était de déterminer la fiabilité de la méthode des résistivités électriques pour cartographier les panaches de pollution dans un environnement de socle. Cinquante stations ont été soumises à mesures au moyen d'un ABEM SAS 300C Terrameter en utilisant le dispositif de Wenner. Les données de résistivité électrique ont été interprétées au moyen d'une technique de calcul itérative. Des

  14. Principles for Sampling Airborne Radioactivity from Stacks

    SciTech Connect

    Glissmeyer, John A.

    2010-10-18

    This book chapter describes the special processes involved in sampling the airborne effluents from nuclear faciities. The title of the book is Radioactive Air Sampling Methods. The abstract for this chapter was cleared as PNNL-SA-45941.

  15. A German Geophysics School Project First steps to bring geophysical topics to schoolclasses

    NASA Astrophysics Data System (ADS)

    Schneider, S.

    2002-12-01

    In Germany Geophysics is a science with almost none or a bad reputation. People do not know to distinguish between Geophysics, Geography and Geology. In order to change the public view on Geosciences, a,School Project Geophysics' is going to be created at the Institute of Meteorology and Geophysics, Johann Wolfgang Goethe University, Frankfurt, which will offer geophysical ideas, methodes and scientific results to schoolclasses. After researches like PISA or TIMSS (third international Math and Nature-Science test) new concepts in education will be required. Interdisciplinary tasks are demanded by national and international commissions.\\The,School Project Geophysics' will be created to bring geophysical themes and results of scientific research into schools. One Day- or one Week-Workshops will help to publish geophysical contents in close cooperation with Physics - and Geography - teachers.\\Hands-on experiments (for advanced pupils) like refraction-Seismics or Magnetic measurements will lead students closer to scientific work and will help to establish personal interests in Earthsciences. Working with personally produced datasets will show the basics of inversion theory and point out the difficulties in creating models. Boundaries of data interpretation (the plurality of variables needed) will teach the school children to see scientific and statistic predictions and declarations more criticaly. Animations and Videos will present global examples (for example of volcanoes or Earthquakes) and lead over to regional sites. Excursions to these sites will help to show fieldwork methods and its problems and will convince to take a different look on topography and landscapes.\\All necessary utilities (Animations, Videos, Pictures and foils) will be offered to teachers in an online-data base which will be installed and managed by the project. Teachers and pupils might get easily into contact with Scientists to discuss geoscientific items. Further on extensions to geographic

  16. Integrated Approaches On Archaeo-Geophysical Data

    NASA Astrophysics Data System (ADS)

    Kucukdemirci, M.; Piro, S.; Zamuner, D.; Ozer, E.

    2015-12-01

    Key words: Ground Penetrating Radar (GPR), Magnetometry, Geophysical Data Integration, Principal Component Analyse (PCA), Aizanoi Archaeological Site An application of geophysical integration methods which often appealed are divided into two classes as qualitative and quantitative approaches. This work focused on the application of quantitative integration approaches, which involve the mathematical and statistical integration techniques, on the archaeo-geophysical data obtained in Aizanoi Archaeological Site,Turkey. Two geophysical methods were applied as Ground Penetrating Radar (GPR) and Magnetometry for archaeological prospection on the selected archaeological site. After basic data processing of each geophysical method, the mathematical approaches of Sums and Products and the statistical approach of Principal Component Analysis (PCA) have been applied for the integration. These integration approches were first tested on synthetic digital images before application to field data. Then the same approaches were applied to 2D magnetic maps and 2D GPR time slices which were obtained on the same unit grids in the archaeological site. Initially, the geophysical data were examined individually by referencing with archeological maps and informations obtained from archaeologists and some important structures as possible walls, roads and relics were determined. The results of all integration approaches provided very important and different details about the anomalies related to archaeological features. By using all those applications, integrated images can provide complementary informations as well about the archaeological relics under the ground. Acknowledgements The authors would like to thanks to Scientific and Technological Research Council of Turkey (TUBITAK), Fellowship for Visiting Scientists Programme for their support, Istanbul University Scientific Research Project Fund, (Project.No:12302) and archaeologist team of Aizanoi Archaeological site for their support

  17. Geophysical Exploration of Castle Remains in Barwałd Górny (Near Kalwaria Zebrzydowska, Poland) Using Electrical Resistivity Tomography (ERT) with Assistance of Depth of Investigation Index (DOI) Method.

    NASA Astrophysics Data System (ADS)

    Glazer, Michał; Kula, Damian; Saternus, Robert; Lewicki, Paweł

    2014-09-01

    In March of 2014 at ruins of the 14th century castle, situated at the top of Mount Żar in Małopolska region, Poland, geophysical surveys were performed. Surveys were planned to investigate remains of the castle that could remain in the ground. Electrical Resistivity Tomography method was used there. In the paper 4 sections have been presented. During interpretation, as the supporting method, maps of Depth-of-Investigation (DOI) index have been used. Results of the surveys can point out potential remains of the castle walls and ruins of buildings that were situated in the stronghold

  18. A Newly Adopted Helicopter Platform for Geophysical and Remote Sensing

    NASA Astrophysics Data System (ADS)

    Meyer, Uwe

    2014-05-01

    The Federal Institute for Geosciences and Natural Resources in Hannover owns a Sikorsky S-76B helicopter for geophysical and remote sensing airborne surveys. This platform has been completely refurbished and in parts newly designed to be fit for easy installations of complex geophysical instruments underneath, upon and within the helicopter. The airborne platform is equipped with a modern basic navigation equipment consisting of several GNSS antennae, state of the art inertial navigation systems, laser altimeter and video camera systems. Different other modules can be added to the helicopter as a state of the art gamma spectrometer, a laser scanner, airborne gravity meters etc. within the cabin. Moreover, external sensing systems as a photogrammetric camera, infraread camera or optional mulitspectral systems can be installed on the outer skin of the cabin. Different kinds of bird systems towed underneath the helicopter can be hooked up using standard cabling, glas fibres or wireless LAN. Available birds are equipped for frequency domain electromagnetics or gradient magnetics (IPHT Jena & Supracon, Jena). Besides, large georadar systems can be installed as well. The helicopter is able as well to carry TEM-gear or system in development. Main survey targets are groundwater systems, mineral deposits and natural hazards.

  19. Introduction to the JEEG Agricultural Geophysics special issue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent advancements such as the availability of personal computers, technologies to store/process large amounts of data, the GPS, and GIS have now made geophysical methods practical for agricultural use. Consequently, there has been a rapid expansion of agricultural geophysics research just over the...

  20. SURFACE GEOPHYSICAL EXPLORATION - COMPENDIUM DOCUMENT

    SciTech Connect

    RUCKER DF; MYERS DA

    2011-10-04

    This report documents the evolution of the surface geophysical exploration (SGE) program and highlights some of the most recent successes in imaging conductive targets related to past leaks within and around Hanford's tank farms. While it is noted that the SGE program consists of multiple geophysical techniques designed to (1) locate near surface infrastructure that may interfere with (2) subsurface plume mapping, the report will focus primarily on electrical resistivity acquisition and processing for plume mapping. Due to the interferences from the near surface piping network, tanks, fences, wells, etc., the results of the three-dimensional (3D) reconstruction of electrical resistivity was more representative of metal than the high ionic strength plumes. Since the first deployment, the focus of the SGE program has been to acquire and model the best electrical resistivity data that minimizes the influence of buried metal objects. Toward that goal, two significant advances have occurred: (1) using the infrastructure directly in the acquisition campaign and (2) placement of electrodes beneath the infrastructure. The direct use of infrastructure was successfully demonstrated at T farm by using wells as long electrodes (Rucker et al., 2010, 'Electrical-Resistivity Characterization of an Industrial Site Using Long Electrodes'). While the method was capable of finding targets related to past releases, a loss of vertical resolution was the trade-off. The burying of electrodes below the infrastructure helped to increase the vertical resolution, as long as a sufficient number of electrodes are available for the acquisition campaign.

  1. Airborne detection of asperities: Linking aerogravimetry surveys and earthquake studies

    NASA Astrophysics Data System (ADS)

    Meyer, U.; Boedecker, G.

    2003-04-01

    During the last decade, airborne gravimetric surveys have become a reliable and useful geophysical method to explore mid to large scale geologic settings. Ocean continent boundaries down to seamounts are detectable using conventional scalar, platform stabilized airborne gravimetry systems. New systems such as 3-D strap-down instruments promise a better spatial resolution recovering the gravity vector. Airborne gravimetric gradiometer systems are already able to detect small scale gradients in high spatial resolution. Following this trend in aerogravimetry, new research applications are emerging. One of the most challenging and interesting new aspects of airborne gravimetry is the systematic search for asperity structures. Asperities are patches of the oceanic or continental crust that are able to store more stress than the surrounding material. If due to stress overload or other mechanic forces the asperity breaks, up to mega-thrust earthquakes are triggered. The character of an asperity to carry more stress than the weaker environment must be related to its physical properties such as composition, thickness and density. Questions connected to define and detect an asperity are: How large is an asperity? Do asperities have sharp boundaries? Are asperities isolated structures? Do asperities have special gravimetric signatures? Wells et al. (2000) found that off southern Chile slip maxima from earthquakes coincide with forearc gravity lows. It is well accepted that in this region seismicity is a product of the subduction on the active continental margin. It is still debated whether subducted asperities from the oceanic plate are individual earthquake sources or if they i.e. trigger the break of asperities in the continental crust. Apart from this, very few investigations have been made trying to connect gravimetry and asperities. Therefore, the GeoForschungsZentrum Potsdam in collaboration with Bayerische Akademie der Wissenschaften in Munich , FU Berlin

  2. Airborne Gravity Gradiometry Resolves a Full Range of Gravity Frequencies

    NASA Astrophysics Data System (ADS)

    Mataragio, J.; Brewster, J.; Mims, J.

    2007-12-01

    mostly targeting large, regional\\- scale crustal structures as well as regional mapping of both lithology and regolith. Air\\-FTGR mapping is especially effective in areas of thick lateritic and/or clay cover where other geophysical methods such as airborne magnetics or electromagnetics become less effective. For instance, an Air\\-FTGR survey was successfully flown in Brazil in the Province of Minas Gerais, where several crustal\\-scale structures associated with iron oxide mineralization were identified ( Mataragio et. al., 2006). In addition, in 2006 Air\\-FTGR had good success in the regional mapping of structures associated with Iron Oxide Copper Gold (IOCG) and uranium mineralization in the Wernecke Mountains in the Yukon, and Northwest Territories, Canada. On the basis of these successful surveys, Bell Geospace has initiated a number of high altitude test surveys aiming at evaluating the performance of the Air\\-FTGR system in capturing low frequency signal that may be associated with regional\\-scale, deeper structures. One of the test surveys was conducted in December of 2006 in Australia, where the performance of Air\\-FTGR and the conventional Airborne Gravity were evaluated. Airborne gravity is currently considered well suited for capturing low frequency signal.

  3. Use of Geophysical and Remote Sensing Techniques During the Comprehensive Test Ban Treaty Organization's Integrated Field Exercise 2014

    NASA Astrophysics Data System (ADS)

    Labak, Peter; Sussman, Aviva; Rowlands, Aled; Chiappini, Massimo; Malich, Gregor; MacLeod, Gordon; Sankey, Peter; Sweeney, Jerry; Tuckwell, George

    2016-04-01

    The Integrated Field Exercise of 2014 (IFE14) was a field event held in the Hashemite Kingdom of Jordan (with concurrent activities in Austria) that tested the operational and technical capabilities of a Comprehensive Test Ban Treaty's (CTBT) on-site inspection (OSI). During an OSI, up to 40 inspectors search a 1000km2 inspection area for evidence of a nuclear explosion. Over 250 experts from ~50 countries were involved in IFE14 (the largest simulation of an OSI to date) and worked from a number of different directions, such as the Exercise Management and Control Teams to execute the scenario in which the exercise was played, to those participants performing as members of the Inspection Team (IT). One of the main objectives of IFE14 was to test Treaty allowed inspection techniques, including a number of geophysical and remote sensing methods. In order to develop a scenario in which the simulated exercise could be carried out, a number of physical features in the IFE14 inspection area were designed and engineered by the Scenario Task Force Group (STF) that the IT could detect by applying the geophysical and remote sensing inspection technologies, as well as other techniques allowed by the CTBT. For example, in preparation for IFE14, the STF modeled a seismic triggering event that was provided to the IT to prompt them to detect and localize aftershocks in the vicinity of a possible explosion. Similarly, the STF planted shallow targets such as borehole casings and pipes for detection by other geophysical methods. In addition, airborne technologies, which included multi-spectral imaging, were deployed such that the IT could identify freshly exposed surfaces, imported materials and other areas that had been subject to modification. This presentation will introduce the CTBT and OSI, explain the IFE14 in terms of goals specific to geophysical and remote sensing methods, and show how both the preparation for and execution of IFE14 meet those goals.

  4. Integrating aerial geophysical data in multiple-point statistics simulations to assist groundwater flow models

    NASA Astrophysics Data System (ADS)

    Dickson, Neil E. M.; Comte, Jean-Christophe; Renard, Philippe; Straubhaar, Julien A.; McKinley, Jennifer M.; Ofterdinger, Ulrich

    2015-08-01

    The process of accounting for heterogeneity has made significant advances in statistical research, primarily in the framework of stochastic analysis and the development of multiple-point statistics (MPS). Among MPS techniques, the direct sampling (DS) method is tested to determine its ability to delineate heterogeneity from aerial magnetics data in a regional sandstone aquifer intruded by low-permeability volcanic dykes in Northern Ireland, UK. The use of two two-dimensional bivariate training images aids in creating spatial probability distributions of heterogeneities of hydrogeological interest, despite relatively `noisy' magnetics data (i.e. including hydrogeologically irrelevant urban noise and regional geologic effects). These distributions are incorporated into a hierarchy system where previously published density function and upscaling methods are applied to derive regional distributions of equivalent hydraulic conductivity tensor K. Several K models, as determined by several stochastic realisations of MPS dyke locations, are computed within groundwater flow models and evaluated by comparing modelled heads with field observations. Results show a significant improvement in model calibration when compared to a simplistic homogeneous and isotropic aquifer model that does not account for the dyke occurrence evidenced by airborne magnetic data. The best model is obtained when normal and reverse polarity dykes are computed separately within MPS simulations and when a probability threshold of 0.7 is applied. The presented stochastic approach also provides improvement when compared to a previously published deterministic anisotropic model based on the unprocessed (i.e. noisy) airborne magnetics. This demonstrates the potential of coupling MPS to airborne geophysical data for regional groundwater modelling.

  5. Occupational exposure to polycyclic aromatic hydrocarbons in airborne particulate matter: validation and application of a gas chromatography-mass spectrometry analytical method.

    PubMed

    Fioretti, Marzia; Catrambone, Tamara; Gordiani, Andrea; Cabella, Renato

    2010-12-01

    This study concerns the validation of an analytical method for the measurement of occupational exposure to trace levels of polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter (APM). Personal exposure to selected PAHs of five workers occupationally exposed to urban pollution in Rome, Italy, was evaluated. The samples were collected over 10 days evenly distributed during winter and summer of 2008. Polycyclic aromatic hydrocarbons were collected by a sampling pump and trapped in polytetrafluoroethylene filters; ultrasonic extraction was applied to extract PAH species from the matrix with toluene, and the concentrated extract was quantitatively analyzed by GC/MS. The analytical method was optimized and validated using a standard reference material of urban dust (SRM 1649a). Detection limits ranged from 0.8 ng per sample for indeno [1,2,3-cd] pyrene to 20.4 ng for sample for anthracene. Experimental results of the 50 personal samples collected showed that phenanthrene was the predominant polycyclic aromatic hydrocarbon [95% CI (32.42-41.13 ng m(-3))]; the highest benzo[a]pyrene concentration was 2.58 ng m(-3), approximately 2-fold higher than European annual target values (1 ng m(-3)). Seasonal variations of personal exposure to selected PAHs suggested higher emissions and reduced atmospheric reactivity of PAH compounds in winter. The analytical method was a suitable procedure for the determination of 13 of the 16 priority PAHs in APM personal samples and can be considered a useful tool to evaluate occupational exposure to low PAH levels.

  6. Geological and geophysical characteristics of massive sulphide deposits: A case study of the Lirhanda massive sulphide deposit of Western Kenya

    NASA Astrophysics Data System (ADS)

    Dindi, E.; Maneno, J. B. J.

    2016-08-01

    An integrated geophysical ground survey was conducted on an airborne electromagnetic (EM) anomaly located in Kakamega forest of Western Kenya. The purpose of the study was to establish the existence of massive sulphides and identify suitable optimal geophysical method(s) for the investigation of similar anomalies. The study was also expected to provide information on the geological and geophysical characteristics of the deposit. Field work involved electromagnetic methods: Vertical Loop (VLEM), Horizontal Loop (HLEM), TURAM EM and potential field methods: gravity and magnetics. Geochemical sampling was carried out concurrently with the geophysical survey. All the geophysical methods used yielded good responses. Several conductors conforming to the strike of the geology were identified. TURAM EM provided a higher resolution of the conductors compared to VLEM and HLEM. The conductors were found to be associated with positive gravity anomalies supporting the presence of bodies of higher density than the horst rock. Only the western section (west of 625W) of the grid is associated with strong magnetic anomalies. East of 625W strong EM and gravity anomalies persist but magnetic anomalies are weak. This may reflect variation in the mineral composition of the conductors from magnetic to non-magnetic. Geochemical data indicates strong copper anomalies (upto 300 ppm) over sections of the grid and relatively strong zinc (upto 200 ppm) and lead (upto 100 ppm) anomalies. There is a positive correlation between the location of the conductors as predicted by TURAM EM and the copper and zinc anomalies. A test drill hole proposed on the basis of the geophysical results of this study struck massive sulphides at a depth of 30m still within the weathered rock zone. Unfortunately, the drilling was stopped before the sulphides could be penetrated. The drill core revealed massive sulphide rich in pyrite and pyrrhotite. An attempt has been made to compare characteristics of the Lirhanda

  7. Geological and geophysical characteristics of massive sulphide deposits: A case study of the Lirhanda massive sulphide deposit of Western Kenya

    NASA Astrophysics Data System (ADS)

    Dindi, E.; Maneno, J. B. J.

    2016-08-01

    An integrated geophysical ground survey was conducted on an airborne electromagnetic (EM) anomaly located in Kakamega forest of Western Kenya. The purpose of the study was to establish the existence of massive sulphides and identify suitable optimal geophysical method(s) for the investigation of similar anomalies. The study was also expected to provide information on the geological and geophysical characteristics of the deposit. Field work involved electromagnetic methods: Vertical Loop (VLEM), Horizontal Loop (HLEM), TURAM EM and potential field methods: gravity and magnetics. Geochemical sampling was carried out concurrently with the geophysical survey. All the geophysical methods used yielded good responses. Several conductors conforming to the strike of the geology were identified. TURAM EM provided a higher resolution of the conductors compared to VLEM and HLEM. The conductors were found to be associated with positive gravity anomalies supporting the presence of bodies of higher density than the horst rock. Only the western section (west of 625W) of the grid is associated with strong magnetic anomalies. East of 625W strong EM and gravity anomalies persist but magnetic anomalies are weak. This may reflect variation in the mineral composition of the conductors from magnetic to non-magnetic. Geochemical data indicates strong copper anomalies (upto 300 ppm) over sections of the grid and relatively strong zinc (upto 200 ppm) and lead (upto 100 ppm) anomalies. There is a positive correlation between the location of the conductors as predicted by TURAM EM and the copper and zinc anomalies. A test drill hole proposed on the basis of the geophysical results of this study struck massive sulphides at a depth of 30m still within the weathered rock zone. Unfortunately, the drilling was stopped before the sulphides could be penetrated. The drill core revealed massive sulphide rich in pyrite and pyrrhotite. An attempt has been made to compare characteristics of the

  8. Geophysical wave tomography

    NASA Astrophysics Data System (ADS)

    Zhou, Chaoguang

    2000-11-01

    This study is concerned with geophysical wave tomography techniques that include advanced diffraction tomography, traveltime calculation techniques and simultaneous attenuation and velocity tomography approaches. We propose the source independent approximation, the Modified Quasi-Linear approximation and develop a fast and accurate diffraction tomography algorithm that uses this approximation. Since the Modified Quasi-Linear approximation accounts for the scattering fields within scatterers, this tomography algorithm produces better image quality than conventional Born approximation tomography algorithm does with or without the presence of multiple scatterers and can be used to reconstruct images of high contrast objects. Since iteration is not required, this algorithm is efficient. We improve the finite difference traveltime calculation algorithm proposed by Vidale (1990). The bucket theory is utilized in order to enhance the sorting efficiency, which accounts for about ten percent computing time improvement for large velocity models. Snell's law is employed to solve the causality problem analytically, which enables the modified algorithm to compute traveltimes accurately and rapidly for high velocity contrast media. We also develop two simultaneous attenuation and velocity tomography approaches, which use traveltimes and amplitude spectra of the observed data, and discuss some of their applications. One approach is processing geophysical data that come from one single survey and the other deals with the repeated survey cases. These approaches are nonlinear and therefore more accurate than linear tomography. A linear system for wave propagation and constant-Q media are assumed in order to develop the tomography algorithms. These approaches not only produce attenuation and velocity images at the same time but also can be used to infer the physical rock properties, such as the dielectric permittivity, the electric conductivity, and the porosity. A crosshole radar

  9. Rapid geophysical surveyor

    SciTech Connect

    Roybal, L.G.; Carpenter, G.S.; Josten, N.E.

    1993-01-01

    The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of Department of Energy (DOE) waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sties where historical records are inaccurate and survey benchmarks have changed due to refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho national Engineering Laboratory (INEL) during the summer of 1992. The RGS was one of several projects funded by the Buried Waste Integrated Demonstration (BWID) program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex (RWMC) on the INEL in September of 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 inches along survey lines spaced 1 foot apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 man-days using conventional ground survey techniques. This report documents the design and demonstration of the RGS concept including the presentation of magnetic data collected at the SDA. The surveys were able to show pit and trench boundaries and determine details of their spatial orientation never before achieved.

  10. Rapid geophysical surveyor

    SciTech Connect

    Roybal, L.G.; Carpenter, G.S.; Josten, N.E.

    1993-07-01

    The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of Department of Energy (DOE) waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sties where historical records are inaccurate and survey benchmarks have changed due to refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho national Engineering Laboratory (INEL) during the summer of 1992. The RGS was one of several projects funded by the Buried Waste Integrated Demonstration (BWID) program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex (RWMC) on the INEL in September of 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 inches along survey lines spaced 1 foot apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 man-days using conventional ground survey techniques. This report documents the design and demonstration of the RGS concept including the presentation of magnetic data collected at the SDA. The surveys were able to show pit and trench boundaries and determine details of their spatial orientation never before achieved.

  11. Application of surface geophysics to ground-water investigations

    USGS Publications Warehouse

    Zohdy, Adel A.R.; Eaton, Gordon P.; Mabey, Don R.

    1974-01-01

    This manual reviews the standard methods of surface geophysics applicable to ground-water investigations. It covers electrical methods, seismic and gravity methods, and magnetic methods. The general physical principles underlying each method and its capabilities and limitations are described. Possibilities for non-uniqueness of interpretation of geophysical results are noted. Examples of actual use of the methods are given to illustrate applications and interpretation in selected geohydrologic environments. The objective of the manual is to provide the hydrogeologist with a sufficient understanding of the capabilities, imitations, and relative cost of geophysical methods to make sound decisions as to when to use of these methods is desirable. The manual also provides enough information for the hydrogeologist to work with a geophysicist in designing geophysical surveys that differentiate significant hydrogeologic changes.

  12. Long-term Geophysical Monitoring of Simulated Clandestine Graves using Electrical and Ground Penetrating Radar Methods: 4-6 Years After Burial.

    PubMed

    Pringle, Jamie K; Jervis, John R; Roberts, Daniel; Dick, Henry C; Wisniewski, Kristopher D; Cassidy, Nigel J; Cassella, John P

    2016-03-01

    This ongoing monitoring study provides forensic search teams with systematic geophysical data over simulated clandestine graves for comparison to active cases. Simulated "wrapped," "naked," and "control" burials were created. Multiple geophysical surveys were collected over 6 years, here showing data from 4 to 6 years after burial. Electrical resistivity (twin electrode and ERI), multifrequency GPR, grave and background soil water were collected. Resistivity surveys revealed that the naked burial had low-resistivity anomalies up to year four but then difficult to image, whereas the wrapped burial had consistent large high-resistivity anomalies. GPR 110- to 900-MHz frequency surveys showed that the wrapped burial could be detected throughout, but the naked burial was either not detectable or poorly resolved. 225-MHz frequency GPR data were optimal. Soil water analyses showed decreasing (years 4 to 5) to background (year 6) conductivity values. Results suggest both resistivity and GPR surveying if burial style unknown, with winter to spring surveys optimal and increasingly important as time increases.

  13. Long-term Geophysical Monitoring of Simulated Clandestine Graves using Electrical and Ground Penetrating Radar Methods: 4-6 Years After Burial.

    PubMed

    Pringle, Jamie K; Jervis, John R; Roberts, Daniel; Dick, Henry C; Wisniewski, Kristopher D; Cassidy, Nigel J; Cassella, John P

    2016-03-01

    This ongoing monitoring study provides forensic search teams with systematic geophysical data over simulated clandestine graves for comparison to active cases. Simulated "wrapped," "naked," and "control" burials were created. Multiple geophysical surveys were collected over 6 years, here showing data from 4 to 6 years after burial. Electrical resistivity (twin electrode and ERI), multifrequency GPR, grave and background soil water were collected. Resistivity surveys revealed that the naked burial had low-resistivity anomalies up to year four but then difficult to image, whereas the wrapped burial had consistent large high-resistivity anomalies. GPR 110- to 900-MHz frequency surveys showed that the wrapped burial could be detected throughout, but the naked burial was either not detectable or poorly resolved. 225-MHz frequency GPR data were optimal. Soil water analyses showed decreasing (years 4 to 5) to background (year 6) conductivity values. Results suggest both resistivity and GPR surveying if burial style unknown, with winter to spring surveys optimal and increasingly important as time increases. PMID:27404604

  14. Combination of electromagnetic, geophysical methods and sedimentological studies for the development of 3D models in alluvial sediments affected by karst (Ebro Basin, NE Spain)

    NASA Astrophysics Data System (ADS)

    Pueyo Anchuela, Óscar; Luzón, Aránzazu; Gil Garbi, Héctor; Pérez, Antonio; Pocoví Juan, Andrés; Soriano, María Asunción

    2014-03-01

    An integrated analysis was carried out in a selected quarry of the oldest terrace of the Ebro River, where a wide gravel unit is characterized by large-scale cross bedding outcrops. This unit has been interpreted as a lake with marginal deltas. Previous sedimentological studies have pointed out that braided rivers have dominated in the area during the Early Pleistocene. The presence of a lake, which in stable conditions (without subsidence) could be hardly developed in a braided fluvial setting, supports that a topographic depression pre-existed. The delta gravels suggest a depth of at least 5 m for this depression. Established models from broadband multifrequency electromagnetic survey and ground penetrating radar (GPR) show that the analyzed area was affected by a long-term karstic subsidence, which generated a doline field in which topographic depressions were filled by marls and marginal gravels, and subsequently affected by minor collapses during different subsidence reactivation episodes. A 3D model of the evolution and meaning of the doline field and its interaction with sedimentation has been developed. This model can be applied in other areas where high-resolution geophysical 3D models are difficult to establish because of the limitations of the geophysical surveys due to the presence of interbedded mudstones, subsiding depressions filled by human activities or near surface water levels.

  15. Modeling for Airborne Contamination

    SciTech Connect

    F.R. Faillace; Y. Yuan

    2000-08-31

    The objective of Modeling for Airborne Contamination (referred to from now on as ''this report'') is to provide a documented methodology, along with supporting information, for estimating the release, transport, and assessment of dose to workers from airborne radioactive contaminants within the Monitored Geologic Repository (MGR) subsurface during the pre-closure period. Specifically, this report provides engineers and scientists with methodologies for estimating how concentrations of contaminants might be distributed in the air and on the drift surfaces if released from waste packages inside the repository. This report also provides dose conversion factors for inhalation, air submersion, and ground exposure pathways used to derive doses to potentially exposed subsurface workers. The scope of this report is limited to radiological contaminants (particulate, volatile and gaseous) resulting from waste package leaks (if any) and surface contamination and their transport processes. Neutron activation of air, dust in the air and the rock walls of the drift during the preclosure time is not considered within the scope of this report. Any neutrons causing such activation are not themselves considered to be ''contaminants'' released from the waste package. This report: (1) Documents mathematical models and model parameters for evaluating airborne contaminant transport within the MGR subsurface; and (2) Provides tables of dose conversion factors for inhalation, air submersion, and ground exposure pathways for important radionuclides. The dose conversion factors for air submersion and ground exposure pathways are further limited to drift diameters of 7.62 m and 5.5 m, corresponding to the main and emplacement drifts, respectively. If the final repository design significantly deviates from these drift dimensions, the results in this report may require revision. The dose conversion factors are further derived by using concrete of sufficient thickness to simulate the drift

  16. Geophysics in Mexico

    NASA Astrophysics Data System (ADS)

    Fucugauchi, J. Urrutia

    The 1986 Annual Meeting of the Union Geofisica Mexicana (UGM) was held in Morelia, Michoacan, Mexico, during November 9-15, 1986. This annual meeting provides an opportunity for the presentation and discussion of new observations, data, interpretations, etc., in the various research areas of geophysics. It is also intended to bring together geophysicists from government institutions, industry, universities, and research centers, along with researchers from other countries. Since a substantial amount of the geophysical data that is gathered in Mexico remains unpublished or is published in internal reports of restricted circulation, it is important to have such a forum for local and foreign researchers. Many U.S. research groups are presently carrying out studies in Mexico (in seismology, tectonics, economic geology, volcanology, etc.), but their participation in these annual meetings has been very limited. Thus, in addition to giving a brief account of the meeting, we would like to encourage future participation by AGU members and also to announce the availability of material published from the meetings (abstracts with program and a proceedings volume).

  17. Geophysical Technologies to Image Old Mine Works

    SciTech Connect

    Kanaan Hanna; Jim Pfeiffer

    2007-01-15

    ZapataEngineering, Blackhawk Division performed geophysical void detection demonstrations for the US Department of Labor Mine Safety and Health Administration (MSHA). The objective was to advance current state-of-practices of geophysical technologies for detecting underground mine voids. The presence of old mine works above, adjacent, or below an active mine presents major health and safety hazards to miners who have inadvertently cut into locations with such features. In addition, the presence of abandoned mines or voids beneath roadways and highway structures may greatly impact the performance of the transportation infrastructure in terms of cost and public safety. Roads constructed over abandoned mines are subject to potential differential settlement, subsidence, sinkholes, and/or catastrophic collapse. Thus, there is a need to utilize geophysical imaging technologies to accurately locate old mine works. Several surface and borehole geophysical imaging methods and mapping techniques were employed at a known abandoned coal mine in eastern Illinois to investigate which method best map the location and extent of old works. These methods included: 1) high-resolution seismic (HRS) using compressional P-wave (HRPW) and S-wave (HRSW) reflection collected with 3-D techniques; 2) crosshole seismic tomography (XHT); 3) guided waves; 4) reverse vertical seismic profiling (RVSP); and 5) borehole sonar mapping. In addition, several exploration borings were drilled to confirm the presence of the imaged mine voids. The results indicated that the RVSP is the most viable method to accurately detect the subsurface voids with horizontal accuracy of two to five feet. This method was then applied at several other locations in Colorado with various topographic, geologic, and cultural settings for the same purpose. This paper presents the significant results obtained from the geophysical investigations in Illinois.

  18. Integrated multidisciplinary processing and interpretation of geophysical data acquired on transects in Barents and Kara seas

    NASA Astrophysics Data System (ADS)

    Roslov, Yu. V.; Sakoulina, T. S.

    2003-04-01

    INTEGRATED MULTIDISCIPLINARY PROCESSING AND INTERPRETATION OF GEOPHYSICAL DATA ACQUIRED ON TRANSECTS IN BARENTS AND KARA SEAS Yu.V. Roslov (1), T.S. Sakoulina (1) (1 - SEVMORGEO State Geophysical Co., 36 Rosenstein St, 198095, St Petersburg, Russia, roslov @sevmorgeo.com) According to Russian arctic offshore transect program State Company Sevmorgeo in cooperation with other Russian state companies carry out multidisciplinary investigations on transects 1-AR and 2-AR in Barents and Kara Seas. Investigations include the following geophysical methods: 4C wide angle refraction/reflection profiling (WARRP), CDP seismic, airborn and/or marine gravity and magnetic. Three levels of the integration has been used on processing and interpretation stage. First, different approaches of kinematic inverse problem and tomographic reconstruction have been applied for kinematic parameters of 4C WARRP data processing. That has allowed extracting of maximum information from the data acquired. As a result stable P and S velocity models have been obtained. Second, dynamic WARRP image focused mainly on Moho boundary has been integrated with CDP image in order to improve the sedimentary layer structure. Third, seismic images have been proven with gravity and magnetic data reaching the model, which fits to observed potential fields. Also gravity and magnetic data successfully fill out information gap in the places where there is a lack of seismic data. Some original technologies of data processing have been developed in the framework of the project. Finally, within the range defined by the data processed the integrated geological-geophysical images the Kara-Barents Shelf Plate structure whole Earth crust thickness along transects 1-AR and 2-AR have been obtained. New geophysical data acquired have forced reviewing of our nderstanding of Barents region geological structure. First of all it concern to south and north Barents depressions. South Barents depression is well known as a geological

  19. Unleashing Geophysics Data with Modern Formats and Services

    NASA Astrophysics Data System (ADS)

    Ip, Alex; Brodie, Ross C.; Druken, Kelsey; Bastrakova, Irina; Evans, Ben; Kemp, Carina; Richardson, Murray; Trenham, Claire; Wang, Jingbo; Wyborn, Lesley

    2016-04-01

    . The first geophysical data collection selected for transformation by GA was Airborne ElectroMagnetics (AEM) data which was held in proprietary-format files, with associated ISO 19115 metadata held in a separate relational database. Existing NetCDF-CF metadata profiles were enhanced to cover AEM and other geophysical data types, and work is underway to formalise the new geophysics vocabulary as a proposed extension to the Climate & Forecasting conventions. The richness and flexibility of HDF5's internal indexing mechanisms has allowed lossless restructuring of the AEM data for efficient storage, subsetting and access via either the NetCDF4/HDF5 APIs or Open-source Project for a Network Data Access Protocol (OPeNDAP) data services. This approach not only supports large-scale HPC processing, but also interactive access to a wide range of geophysical data in user-friendly environments such as iPython notebooks and more sophisticated cloud-enabled portals such as the Virtual Geophysics Laboratory (VGL). As multidimensional AEM datasets are relatively complex compared to other geophysical data types, the general approach employed in this project for modernizing AEM data is likely to be applicable to other geophysics data types. When combined with the use of standards-based data services and APIs, a coordinated, systematic modernisation will result in vastly improved accessibility to, and usability of, geophysical data in a wide range of computational environments both within and beyond the geophysics community.

  20. Geophysical and Geologic Training of the Afghan Geological Survey, May, 2008

    NASA Astrophysics Data System (ADS)

    Mooney, W. D.; Bohannon, R.; Abraham, J.; Medlin, J.

    2008-12-01

    Afghanistan lies within the Alpine-Himalayan orogeny, and consists of four primary tectonic units: (1) the North Afghan Platform, part of the greater Kazakhstan craton that includes Turkmenistan and Uzbekistan; (2) the mountainous Hindu Kush-Pamirs in the northeast; (3) the transpressional plate boundary at the Chaman fault near the border with Pakistan; and (4) the southern accreted terranes located south of the east-west oriented Herat fault. The diverse geology of Afghanistan affords the country abundant natural resources, as well as many natural hazards. In order to assist in the identification of these resources and to map hazardous faults, a multi-agency consortium including the Afghan Ministry of Mines and Industry, the USGS and the US Navel Research Lab conducted a detailed airborne geophysical survey of the western half of Afghanistan during 2007. Over 110,000 km of data were collected, including aeromagnetic, gravity, hyperspectral imagery, synthetic aperture radar and photogrammetric data. These data provide remarkable images of the surficial and sub-surface structure of the country. Armed with these new, high quality data, USGS trainers conducted an in-depth training course at the offices of the Afghan Geological Survey (AGS) during May, 2008. Eighty staff members of the AGS attended the four-day course which covered the following topics: (1) the geology and tectonics of Afghanistan; (2) a synthesis of modern plate tectonic processes; (3) use of geophysical and geological data to identify natural resources and hazardous faults. Particular emphasis was placed on oil and gas, mineral, coal and water resources. Earthquake and landslide hazards in Afghanistan were also discussed in detail. The building of scientific and technical capabilities at the AGS is a high priority because the development of their natural resources will have a positive impact on economic growth in Afghanistan. Future courses will benefit from hands-on training in methods of

  1. Exemplary geophysical investigations on coal seam fires in Northern China

    NASA Astrophysics Data System (ADS)

    Lambrecht, A.; Meyer, U.; Rüter, H.; Gundelach, V.; Lindner, H.; Schaumann, G.; Schlömer, S.; Guangliang, L.; Bing, K.; Jianjun, W.

    2009-04-01

    Within the framework of the Sino-German research initiative "Innovative technologies for exploration, extinction and monitoring of coal fires in Northern China" different geophysical methods have been applied. The investigation area was the coal fire district of Wuda, located in the south-central part of the Inner Mongolia Autonomous Region of Northern China. The Wuda coalfield is bordering in southeast with the Helan Shan (Helan Mountains), in the east with the mountains of the Ordos Massif, while in the west and north with the Gobi desert. It is a gentle north-south striking structural syncline with an aerial extent of 40 km2 and with elevations ranging between 1100 and 1300 m above sea level. The survey area is covered mainly by sandstone. Up to 18 mined coal seams extend to greater depths varying from a few metres down to several hundreds of metres below surface. The objective of subsequent geophysical surveys was to detect areas affected by coal seam fires by means of physical parameters acquired over the burning and burnt coal seams, to find out which methods are useful for fire detection, to accompany the extinguishing process and to control successful extinction. Airborne methods used are helicopter borne electromagnetics (HEM) and magnetics. Ground surveys for measuring transient electromagnetics, magnetics, ground penetrating radar and near surface temperature were carried out in selected parts of the helicopter survey. Ground penetrating radar (GPR) is an ideal method to detect voids in depth less than 50 m. An important point to extinguish a coal fire is to know the paths of oxygen transport from the surface to the fire. Some crevices which are potential paths for oxygen can be determined by GPR due to the resolution of the chosen frequency. The GPR system applied was built by GSSI and utilized for three different antennae length. The centre frequencies are 40, 80 and 200 MHz. A 200 MHz system was used to get detailed information close to the surface

  2. Geophysical Signitures From Hydrocarbon Contaminated Aquifers

    NASA Astrophysics Data System (ADS)

    Abbas, M.; Jardani, A.

    2015-12-01

    The task of delineating the contamination plumes as well as studying their impact on the soil and groundwater biogeochemical properties is needed to support the remediation efforts and plans. Geophysical methods including electrical resistivity tomography (ERT), induced polarization (IP), ground penetrating radar (GPR), and self-potential (SP) have been previously used to characterize contaminant plumes and investigate their impact on soil and groundwater properties (Atekwana et al., 2002, 2004; Benson et al., 1997; Campbell et al., 1996; Cassidy et al., 2001; Revil et al., 2003; Werkema et al., 2000). Our objective was to: estimate the hydrocarbon contamination extent in a contaminated site in northern France, and to adverse the effects of the oil spill on the groundwater properties. We aim to find a good combination of non-intrusive and low cost methods which we can use to follow the bio-remediation process, which is planned to proceed next year. We used four geophysical methods including electrical resistivity tomography, IP, GPR, and SP. The geophysical data was compared to geochemical ones obtained from 30 boreholes installed in the site during the geophysical surveys. Our results have shown: low electrical resistivity values; high chargeability values; negative SP anomalies; and attenuated GPR reflections coincident with groundwater contamination. Laboratory and field geochemical measurements have demonstrated increased groundwater electrical conductivity and increased microbial activity associated with hydrocarbon contamination of groundwater. Our study results support the conductive model suggested by studies such as Sauck (2000) and Atekwana et al., (2004), who suggest that biological alterations of hydrocarbon contamination can substantially modify the chemical and physical properties of the subsurface, producing a dramatic shift in the geo-electrical signature from resistive to conductive. The next stage of the research will include time lapse borehole

  3. Airborne Gamma-Spectrometry in Switzerland

    SciTech Connect

    Butterweck, Gernot; Bucher, Benno; Rybach, Ladislaus

    2008-08-07

    Airborne gamma-spectrometry is able to obtain fast radiological information over large areas. The airborne gamma-spectrometry unit deployed in Switzerland by the Swiss National Emergency Operations Centre (NEOC) consists of a Swiss army Super Puma helicopter equipped with four NaI-Detectors with a total volume of 17 liters, associated electronics and a real-time data evaluation and mapping unit developed by the Swiss Federal Institute of Technology (ETH) and the Paul Scherrer Institut (PSI). The operational readiness of the airborne gamma-spectrometry system is validated in annual exercises of one week duration. Data from 2005 and 2006 exercises are represented in maps of {sup 137}Cs activity concentration for two towns located in southern and western Switzerland. An indicator of man-made radioactivity (MMGC ratio) is demonstrated for an area with four different types of nuclear installations. The intercomparison between airborne gamma-spectrometry and ground measurements showed good agreement between both methods.

  4. Geophysics of Mars

    NASA Technical Reports Server (NTRS)

    Wells, R. A.

    1979-01-01

    A physical model of Mars is presented on the basis of light-scattering observations of the Martian atmosphere and surface and interior data obtained from observations of the geopotential field. A general description of the atmosphere is presented, with attention given to the circulation and the various cloud types, and data and questions on the blue haze-clearing effect and the seasonal darkening wave are summarized and the Mie scattering model developed to explain these observations is presented. The appearance of the planet from earth and spacecraft through Mariner 9 is considered, and attention is given to the preparation of topographical contour maps, the canal problem and large-scale lineaments observed from Mariner 9, the gravity field and shape of the planet and the application of Runcorn's geoid/convection theory to Mars. Finally, a summary of Viking results is presented and their application to the understanding of Martian geophysics is discussed.

  5. Sampling functions for geophysics

    NASA Technical Reports Server (NTRS)

    Giacaglia, G. E. O.; Lunquist, C. A.

    1972-01-01

    A set of spherical sampling functions is defined such that they are related to spherical-harmonic functions in the same way that the sampling functions of information theory are related to sine and cosine functions. An orderly distribution of (N + 1) squared sampling points on a sphere is given, for which the (N + 1) squared spherical sampling functions span the same linear manifold as do the spherical-harmonic functions through degree N. The transformations between the spherical sampling functions and the spherical-harmonic functions are given by recurrence relations. The spherical sampling functions of two arguments are extended to three arguments and to nonspherical reference surfaces. Typical applications of this formalism to geophysical topics are sketched.

  6. Serious games for Geophysics

    NASA Astrophysics Data System (ADS)

    Lombardo, Valerio; Rubbia, Giuliana

    2015-04-01

    Childhood stage is indispensable in the education of human beings and especially critical to arise scientific interest in children. We discuss the participatory design of a didactic videogame, i.e. a "serious" game to teach geophysics and Earth sciences to high and low-school students. Geophysics is the application of the laws and techniques of physics to uncover knowledge about the earth's dynamic processes and subsurface structure. It explores phenomena such as earthquakes, volcanoes, tsunamis to improve our understanding of the earth's physical processes and our ability to predict reoccurrences. Effective mitigation of risks from catastrophic geologic hazards requires knowledge and understanding of local geology and geologic processes. Scientific outreach can be defined as discourse activity, whose main objective is to communicate some knowledge previously produced in scientific contexts to a non-expert massive audience. One of the difficulties science educators need to overcome is to explain specific concepts from a given discipline in a language simple and understandable for their audience. Digital games today play a large role in young people's lives. Games are directly connected to the life of today's adolescents. Therefore, digital games should be included and broached as a subject in the classroom. The ardor and enthusiasm that digital games evoke in teenagers has indeed brought many researchers, school leaders and teachers to the question "how video games" can be used to engage young people and support their learning inside the classroom. Additionally, studies have shown that digital games can enhance various skills such as the ability to concentrate, stamina, tactical aptness, anticipatory thinking, orientation in virtual spaces, and deductive reasoning. Thus, videogames become an effective didactic mechanism and should have a place in the classroom. The project aims to explore the potentials of entertainment technologies in educational processes

  7. Development and comparison of methods using MS scan and selective ion monitoring modes for a wide range of airborne VOCs.

    PubMed

    Jia, Chunrong; Batterman, Stuart; Chernyak, Sergei

    2006-10-01

    Adsorbent sampling with analysis by thermal desorption, gas chromatography and mass spectrometry (TD/GC/MS) offers many advantages for volatile organic compounds (VOCs) and thus is increasingly used in many applications. For environmental samples and other complex mixtures, the MS detector typically is operated in the scan mode to aid identification of co-eluting compounds. However, scan mode does not achieve the optimal sensitivity, thus compounds occurring at low concentrations may not be detected. This paper develops and evaluates the application of a more sensitive TD/GC/MS method using selective ion monitoring (SIM) that is applicable to VOC mixtures found in ambient and indoor air. Based on toxicity and prevalence, 94 VOCs (including terpenes, aromatic, halogenated and aliphatic compounds) were selected as target compounds. Two analytical methods were developed: a conventional full scan method for ions from 29 to 270 m/z; and a SIM method using 16 time windows and different ions selected for the compounds in each window. Both methods used the same Tenax GR adsorbent sampling tubes, TD and GC parameters, and target and qualifier ions. Laboratory tests determined calibrations, method detection limits (MDLs), precisions, recoveries and storage stability. Field tests compared scan and SIM mode analyses for duplicate samples of indoor air in 51 houses and outdoor air at 41 sites. Statistical analyses included the development of error/precision models. The laboratory tests showed that most compounds demonstrated excellent precision (<10% for concentrations exceeding approximately 0.5 microg m(-3)), good linearity, near identical calibrations for scan and SIM modes, a wide dynamic range (up to 1500 microg m(-3)), and negligible storage losses after 1 month (7 compounds showed moderate losses). SIM mode MDLs ranged from 0.004 to 0.27 microg m(-3), representing a modest (1.1 to 22-fold) improvement compared to scan mode. However, in field tests the SIM method detected

  8. Archaeological Geophysics in Israel: Past, Present and Future

    NASA Astrophysics Data System (ADS)

    Eppelbaum, L. V.

    2009-04-01

    et al., 1999; Reeder et al., 2004; Reinhardt et al., 2006; Reich et al., 2003; Ron et al., 2003; Segal et al., 2003; Sternberg and Lass, 2007; Sternberg et al., 1999; Verri et al., 2004; Weiner et al., 1993; Weinstein-Evron et al., 1991, 2003; Weiss et al., 2007; Witten et al., 1994), and (3) future [2010 -]. The past stage with several archaeoseismic reviews and very limited application of geophysical methods was replaced by the present stage with the violent employment of numerous geophysical techniques (first of all, high-precise magnetic survey and GPR). It is supposed that the future stage will be characterized by extensive development of multidiscipline physical-archaeological databases (Eppelbaum et al., 2009b), utilization of supercomputers for 4D monitoring and ancient sites reconstruction (Foster et al., 2001; Pelfer et al., 2004) as well as wide application of geophysical surveys using remote operated vehicles at low altitudes (Eppelbaum, 2008a). REFERENCES Batey, R.A., 1987. Subsurface Interface Radar at Sepphoris, Israel 1985. Journal of Field Archaeology, 14 (1), 1-8. Bauman, P., Parker, D., Coren, A., Freund, R., and Reeder, P., 2005. Archaeological Reconnaissance at Tel Yavne, Israel: 2-D Electrical Imaging and Low Altitude Aerial Photography. CSEG Recorder, No. 6, 28-33. Ben-Dor, E., Portugali, J., Kochavi, M., Shimoni, M., and Vinitzky, L., 1999. Airborne thermal video radiometry and excavation planning at Tel Leviah, Golan Heights, Israel. Journal of Field Archaeology, 26 (2), 117-127. Ben-Menahem, A., 1979. Earthquake catalogue for the Middle East (92 B.C. - 1980 A.D.). Bollettino di Geofisica Teorica ed Applicata, 21 (84), 245-310. Ben-Yosef, E., Tauxe, L., Ronb, H., Agnon, A., Avner, U., Najjar, M., and Levy, T.E., 2008. A new approach for geomagnetic archaeointensity research: insights on ancient metallurgy in the Southern Levant. Journal of Archaeological Science, 25, 2863-2879. Berkovitch, A.L., Eppelbaum, L.V., and Basson, U., 2000

  9. Multispectral thermal airborne TASI-600 data to study the Pompeii (IT) archaeological area

    NASA Astrophysics Data System (ADS)

    Palombo, Angelo; Pascucci, Simone; Pergola, Nicola; Pignatti, Stefano; Santini, Federico; Soldovieri, Francesco

    2016-04-01

    calibration of the raw data by using the RADCORR software provided by ITRES (Canada) and the application of a new correction tool for blinking pixel correction, developed by CNR (Italy); (b) atmospheric compensation of the TIR data by applying the ISAC (In-Scene Atmospheric Compensation) algorithm [7]; (c) Temperature Emissivity Separation (TES) according to the methods described by [8] to obtain a LST map. The obtained preliminary results are encouraging, even though, suitable integration approaches with the classical geophysical investigation techniques have to be improved for a rapid and cost-effective assessment of the buildings status. The importance of this study, moreover, is related to the evaluation of the impact of the unmanned aerial vehicles (UAVs) imaging in the Conservation of Cultural Heritage that can provide: i) low cost imaging; ii) very high spatial resolution thermal imaging. References 1. Scollar, I., Tabbagh, A., Hesse, A., Herzog, A., 1990. Archaeological Prospecting andRemote Sensing. Cambridge University Press, Cambridge.Seitz, C., Altenbach, H., 2011. Project ARCHEYE: the quadrocopter as the archaeologists eye. Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. 38 2. Sever, T.L., Wagner, D.W., 1991. Analysis of prehistoric roadways in Chaco Canyonusing remotely sensed data. In: Trombold, C.D. (Ed.), Ancient Road Networksand Settlement Hierarchies in the New World. Cambridge University Press,Cambridge, pp. 42 3. Pascucci S., Cavalli R M., Palombo A. & Pignatti S. (2010), Suitability of CASI and ATM airborne remote sensing data for archaeological subsurface structure detection under different land cover: the Arpi case study (Italy). In Journal of Geophysics and Engineering, Vol. 7 (2), pp. 183-189. 4. Bassani C., Cavalli R.M., Goffredo, R., Palombo A., Pascucci S. & Pignatti S. (2009), Specific spectral bands for different land cover contexts to improve the efficiency of remote sensing archaeological prospection: The Arpi case study. In Journal of

  10. Sedimentological analysis using geophysical well logs

    SciTech Connect

    Izotova, T.S. )

    1993-09-01

    The application of geophysical well logs in sedimentology and stratigraphic prospecting holds great promise in solving a number of geological problems. A suite of logs provides data on a wide range of rock properties: vertical and lateral variation of resistivity, natural polarization, natural and induced radioactivity, shear strength, and acoustic properties. Each of these properties is controlled by the depositional environment of the sediments and their later diagenesis. The attention of geologists and geophysicists is drawn to new techniques in the interpretation of geophysical well logs for exploration, appraisal, and development of oil and gas fields. The relationship between geophysical logs and depositional environments is explored. Bulk composition, rock structure, and texture and facies variation can be quantified by electric log parameters. Also, the possibility of using logs to demonstrate long- and short-period sedimentary cycles is demonstrated. Methods of sedimentological analysis using geophysical well logs are demonstrated. The importance of a genetic approach in the interpretation of geological sequences and paleogeological reconstructions is emphasized using examples taken from oil and gas prospecting operations in the Ukraine.

  11. Airborne infectious disease and the suppression of pulmonary bioaerosols.

    PubMed

    Fiegel, Jennifer; Clarke, Robert; Edwards, David A

    2006-01-01

    The current understanding of airborne pathogen spread in relation to the new methods of suppressing exhaled bioaerosols using safe surface-active materials, such as isotonic saline, is reviewed here. We discuss the physics of bioaerosol generation in the lungs, what is currently known about the relationship between expired bioaerosols and airborne infectious disease and current methods of airborne infectious disease containment. We conclude by reviewing recent experiments that suggest the delivery of isotonic saline can significantly diminish exhaled aerosol--generated from airway lining fluid in the course of natural breathing. We also discuss these implications in relation to airborne infectious disease control.

  12. EDITORIAL: Special issue on near surface geophysics for the study and the management of historical resources Special issue on near surface geophysics for the study and the management of historical resources

    NASA Astrophysics Data System (ADS)

    Eppelbaum, L. V.; Masini, N.; Soldovieri, F.

    2010-06-01

    This special issue of the Journal of Geophysics and Engineering hosts a selection of the papers that were presented at the session entitled `Near surface geophysics for the study and the management of historical resources: past, present and future', organized within the framework of the General Assembly of the European Geosciences Union (Vienna, Austria, 19-24 April 2009). As the conveners, we invited the active participants of this session to prepare papers reflecting their presentations and submit them for publication in the Journal of Geophysics and Engineering. This special issue presents the papers which have passed through the prolonged and stringent reviewing process. The papers presented in this issue illustrate the application of novel instrumentation, surface and airborne remote sensing techniques, as well as data processing oriented both to new archaeological targets characterization and cultural heritage conservation. In this field, increasing interest has been observed in recent years in non-destructive and non-invasive geophysical test methods. They allow one to overcome the subjectivity and ambiguity arising from the number and locations of the sites chosen to perform the destructive examination. In addition, very recently, much attention has been given to the integration of the classical geophysical techniques (GPR, magnetic, ERT, IP) with new emerging surface and subsurface sensing techniques (optical sensors, lidar, microwave tomography, MASW) for a combined monitoring of archaeological constructions and artefacts. We hope that the presented research papers will be interesting for readers in the different branches of environmental and cultural heritage sciences and will attract new potential contributors to the important topics of archaeological targets recognition, cultural heritage monitoring and diagnostics. Statistically, every day several tens of significant archaeological objects are destroyed and damaged throughout the Earth, and we hope

  13. Archaeological Geophysics in Israel: Past, Present and Future

    NASA Astrophysics Data System (ADS)

    Eppelbaum, L. V.

    2009-04-01

    et al., 1999; Reeder et al., 2004; Reinhardt et al., 2006; Reich et al., 2003; Ron et al., 2003; Segal et al., 2003; Sternberg and Lass, 2007; Sternberg et al., 1999; Verri et al., 2004; Weiner et al., 1993; Weinstein-Evron et al., 1991, 2003; Weiss et al., 2007; Witten et al., 1994), and (3) future [2010 -]. The past stage with several archaeoseismic reviews and very limited application of geophysical methods was replaced by the present stage with the violent employment of numerous geophysical techniques (first of all, high-precise magnetic survey and GPR). It is supposed that the future stage will be characterized by extensive development of multidiscipline physical-archaeological databases (Eppelbaum et al., 2009b), utilization of supercomputers for 4D monitoring and ancient sites reconstruction (Foster et al., 2001; Pelfer et al., 2004) as well as wide application of geophysical surveys using remote operated vehicles at low altitudes (Eppelbaum, 2008a). REFERENCES Batey, R.A., 1987. Subsurface Interface Radar at Sepphoris, Israel 1985. Journal of Field Archaeology, 14 (1), 1-8. Bauman, P., Parker, D., Coren, A., Freund, R., and Reeder, P., 2005. Archaeological Reconnaissance at Tel Yavne, Israel: 2-D Electrical Imaging and Low Altitude Aerial Photography. CSEG Recorder, No. 6, 28-33. Ben-Dor, E., Portugali, J., Kochavi, M., Shimoni, M., and Vinitzky, L., 1999. Airborne thermal video radiometry and excavation planning at Tel Leviah, Golan Heights, Israel. Journal of Field Archaeology, 26 (2), 117-127. Ben-Menahem, A., 1979. Earthquake catalogue for the Middle East (92 B.C. - 1980 A.D.). Bollettino di Geofisica Teorica ed Applicata, 21 (84), 245-310. Ben-Yosef, E., Tauxe, L., Ronb, H., Agnon, A., Avner, U., Najjar, M., and Levy, T.E., 2008. A new approach for geomagnetic archaeointensity research: insights on ancient metallurgy in the Southern Levant. Journal of Archaeological Science, 25, 2863-2879. Berkovitch, A.L., Eppelbaum, L.V., and Basson, U., 2000

  14. Liquid-phase sample preparation method for real-time monitoring of airborne asbestos fibers by dual-mode high-throughput microscopy.

    PubMed

    Cho, Myoung-Ock; Kim, Jung Kyung; Han, Hwataik; Lee, Jeonghoon

    2013-01-01

    Asbestos that had been used widely as a construction material is a first-level carcinogen recognized by the World Health Organization. It can be accumulated in body by inhalation causing virulent respiratory diseases including lung cancer. In our previous study, we developed a high-throughput microscopy (HTM) system that can minimize human intervention accompanied by the conventional phase contrast microscopy (PCM) through automated counting of fibrous materials and thus significantly reduce analysis time and labor. Also, we attempted selective detection of chrysotile using DksA protein extracted from Escherichia coli through a recombinant protein production technique, and developed a dual-mode HTM (DM-HTM) by upgrading the HTM device. We demonstrated that fluorescently-labeled chrysotile asbestos fibers can be identified and enumerated automatically among other types of asbestos fibers or non-asbestos particles in a high-throughput manner through a newly modified HTM system for both reflection and fluorescence imaging. However there is a limitation to apply DM-HTM to airborne sample with current air collecting method due to the difficulty of applying the protein to dried asbestos sample. Here, we developed a technique for preparing liquid-phase asbestos sample using an impinger normally used to collect odor molecules in the air. It would be possible to improve the feasibility of the dual-mode HTM by integrating a sample preparation unit for making collected asbestos sample dispersed in a solution. The new technique developed for highly sensitive and automated asbestos detection can be a potential alternative to the conventional manual counting method, and it may be applied on site as a fast and reliable environmental monitoring tool.

  15. Assessing modern ground survey methods and airborne laser scanning for digital terrain modelling: A case study from the Lake District, England

    NASA Astrophysics Data System (ADS)

    Gallay, Michal; Lloyd, Christopher D.; McKinley, Jennifer; Barry, Lorraine

    2013-02-01

    This paper compares the applicability of three ground survey methods for modelling terrain: one man electronic tachymetry (TPS), real time kinematic GPS (GPS), and terrestrial laser scanning (TLS). Vertical accuracy of digital terrain models (DTMs) derived from GPS, TLS and airborne laser scanning (ALS) data is assessed. Point elevations acquired by the four methods represent two sections of a mountainous area in Cumbria, England. They were chosen so that the presence of non-terrain features is constrained to the smallest amount. The vertical accuracy of the DTMs was addressed by subtracting each DTM from TPS point elevations. The error was assessed using exploratory measures including statistics, histograms, and normal probability plots. The results showed that the internal measurement accuracy of TPS, GPS, and TLS was below a centimetre. TPS and GPS can be considered equally applicable alternatives for sampling the terrain in areas accessible on foot. The highest DTM vertical accuracy was achieved with GPS data, both on sloped terrain (RMSE 0.16 m) and flat terrain (RMSE 0.02 m). TLS surveying was the most efficient overall but veracity of terrain representation was subject to dense vegetation cover. Therefore, the DTM accuracy was the lowest for the sloped area with dense bracken (RMSE 0.52 m) although it was the second highest on the flat unobscured terrain (RMSE 0.07 m). ALS data represented the sloped terrain more realistically (RMSE 0.23 m) than the TLS. However, due to a systematic bias identified on the flat terrain the DTM accuracy was the lowest (RMSE 0.29 m) which was above the level stated by the data provider. Error distribution models were more closely approximated by normal distribution defined using median and normalized median absolute deviation which supports the use of the robust measures in DEM error modelling and its propagation.

  16. A Section-based Method For Tree Species Classification Using Airborne LiDAR Discrete Points In Urban Areas

    NASA Astrophysics Data System (ADS)

    Chunjing, Y. C.; Hui, T.; Zhongjie, R.; Guikai, B.

    2015-12-01

    As a new approach to forest inventory utilizing, LiDAR remote sensing has become an important research issue in the past. Lidar researches initially concentrate on the investigation for mapping forests at the tree level and identifying important structural parameters, such as tree height, crown size, crown base height, individual tree species, and stem volume etc. But for the virtual city visualization and mapping, the traditional methods of tree classification can't satisfy the more complex conditions. Recently, the advanced LiDAR technology has generated new full waveform scanners that provide a higher point density and additional information about the reflecting characteristics of trees. Subsequently, it was demonstrated that it is feasible to detect individual overstorey trees in forests and classify species. But the important issues like the calibration and the decomposition of full waveform data with a series of Gaussian functions usually take a lot of works. What's more, the detection and classification of vegetation results relay much on the prior outcomes. From all above, the section-based method for tree species classification using small footprint and high sampling density lidar data is proposed in this paper, which can overcome the tree species classification issues in urban areas. More specific objectives are to: (1)use local maximum height decision and four direction sections certification methods to get the precise locations of the trees;(2) develop new lidar-derived features processing techniques for characterizing the section structure of individual tree crowns;(3) investigate several techniques for filtering and analyzing vertical profiles of individual trees to classify the trees, and using the expert decision skills based on percentile analysis;(4) assess the accuracy of estimating tree species for each tree, and (5) investigate which type of lidar data, point frequency or intensity, provides the most accurate estimate of tree species

  17. Instability of Pollard's exact solution for geophysical ocean flows

    NASA Astrophysics Data System (ADS)

    Ionescu-Kruse, Delia

    2016-08-01

    In this paper we apply the short-wavelength perturbation method to derive instability criteria for the three-dimensional nonlinear Pollard geophysical waves. We show that these waves are linearly unstable when the wave steepness exceeds a certain threshold.

  18. An Integration of Geophysical Methods for the Determination of Subsurface Structure of the Intra-Mountain Plains: The CASES of Rieti and Leonessa (CENTRAL APENNINES, ITALY)

    NASA Astrophysics Data System (ADS)

    Skrame, K.; Di Filippo, M.; Di Nezza, M.

    2014-12-01

    This work, carried out with an integrated methodological approach, describes the acquisition of gravity data and their integration with different geophysical techniques, in order to map and model the thickness of unconsolidated deposits and determine the bedrock configuration of two different intra-mountain plains: Leonessa plain (hereafter LP) and Rieti plain (hereafter RP). The LP and the RP, the test areas of this study, are typical intra-mountain depressions of Center Apennines, related to the Plio-Quaternary extensional tectonic. Both basins are characterized by thick Quaternary fluvial-lacustrine deposits (gravel, sand and clay) overlaying the Meso-Cenozoic pelagic basin deposits. On the LP, the study involved an area of 62 km2 occupied by 333 gravity stations. Instead, on the RP, the study area, of 35 km2, were occupied by 170 gravity stations. The gravity data resulted from the network adjustment were used to calculate the Bouguer anomaly map. Subtracting the regional field from the Bouguer anomaly produced the residual anomaly map. In order to determine the distribution of the sedimentary infill, a 2D gravity modeling was developed in the region, including five profiles in the case study of LP and six profiles in the case study of RP. A realistic density of the unconsolidated Quaternary deposits (1.75-2,00 g/cm3 in the case of LP and 2,15 g/cm3 in the case of RP), a density of 2.50 g/cm3 for the Travertine and a density of 2.60 g/cm3 for the Meso-Cenozoic pelagic basin deposits were used to constrain the 2D gravimetric models. The models match quite well with the information determined from a collection of existing well logs and geophysical data obtained by the ambient noise, MASW and Downhole measurements. Finally, referring to these models, we were able to evaluate the thickness of the Quaternary sedimentary infilling and to define the 3D bedrock configuration of the basins. These 3D models represent a useful starting point for future activities such as

  19. Mars Airborne Prospecting Spectrometer

    NASA Astrophysics Data System (ADS)

    Steinkraus, J. M.; Wright, M. W.; Rheingans, B. E.; Steinkraus, D. E.; George, W. P.; Aljabri, A.; Hall, J. L.; Scott, D. C.

    2012-06-01

    One novel approach towards addressing the need for innovative instrumentation and investigation approaches is the integration of a suite of four spectrometer systems to form the Mars Airborne Prospecting Spectrometers (MAPS) for prospecting on Mars.

  20. An Emerging Role for Geophysics in Watershed Hydrologic Investigations

    NASA Astrophysics Data System (ADS)

    Knight, R.; Robinson, D.

    2005-12-01

    There is growing recognition of the challenges we face, in many parts of the world, in finding and maintaining clean sources of water for human consumption and agricultural use, while balancing the needs of the natural world. Watershed hydrologic investigations can be used to develop an improved understanding of the controls on the quantity, movement and quality of water, thus enhancing our ability to better protect and manage our water resources. Geophysical methods can play a central role in these investigations. CUAHSI (Consortium of Universities for the Advancement of Hydrologic Sciences) is developing, with the support of the National Science Foundation, a Hydrologic Measurement Facility (HMF), which contains a Geophysics Module. Through the HMF-Geophysics Module our objective is to determine how best to utilize geophysical instrumentation and engage geophysical expertise in addressing key challenges in watershed-scale characterization. We approach the development of HMF-Geophysics with the following questions: 1) What are the parameters that need to be measured in order to adequately describe the quantity, movement and quality of water, and at what spatial and temporal scale do these parameters need to be measured? 2) What can we measure with our geophysical instruments and methodologies, and what are the relevant spatial and temporal scales? 3) Given the answers to 1) and 2) above, what can we do today with geophysics that integrates with hydrological monitoring and modeling approaches, and provides a significant advancement over other forms of measurement? 4) What are the critical research needs in advancing the use of geophysics for watershed hydrologic investigations? When we consider the state-of-the-science in the use of geophysics for all near-surface applications, we identify four cross-cutting areas of research activity that complement the goals of HMF-Geophysics. One area of research is focused on improving the accuracy of our estimates of

  1. Assessing inhalation exposure from airborne soil contaminants

    SciTech Connect

    Shinn, J.H.

    1998-04-01

    A method of estimation of inhalation exposure to airborne soil contaminants is presented. this method is derived from studies of airborne soil particles with radioactive tags. The concentration of contaminants in air (g/m{sup 3}) can be derived from the product of M, the suspended respirable dust mass concentration (g/m{sup 3}), S, the concentration of contaminant in the soil (g/g), and E{sub f}, an enhancement factor. Typical measurement methods and values of M, and E{sub f} are given along with highlights of experiences with this method.

  2. Installation restoration research program: Assessment of geophysical methods for subsurface geologic mapping, cluster 13, Edgewood Area, Aberdeen Proving Ground, Maryland. Final report

    SciTech Connect

    Butler, D.K.; Sharp, M.K.; Sjostrom, K.J.; Simms, J.E.; Llopis, J.L.

    1996-10-01

    Seismic refraction, electrical resistivity, and transient electromagnetic surveys were conducted at a portion of Cluster 13, Edgewood Area of Aberdeen Proving Ground, Maryland. Seismic refraction cross sections map the topsoil layer and the water table (saturated zone). The water table elevations from the seismic surveys correlate closely with water table elevations in nearby monitoring wells. Electrical resistivity cross sections reveal a very complicated distribution of sandy and clayey facies in the upper 10 - 15 m of the subsurface. A continuous surficial (topsoil) layer correlates with the surficial layer of the seismic section and nearby boring logs. The complexity and details of the electrical resistivity cross section correlate well with boring and geophysical logs from nearby wells. The transient electromagnetic surveys map the Pleistocene-Cretaceous boundary, the saprolite, and the top of the Precambrian crystalline rocks. Conducting the transient electromagnetic surveys on a grid pattern allows the construction of a three-dimensional representation of subsurface geology (as represented by variations of electrical resistivity). Thickness and depth of the saprolitic layer and depth to top of the Precambrian rocks are consistent with generalized geologic cross sections for the Edgewood Area and depths projected from reported depths at the Aberdeen Proving Ground NW boundary using regional dips.

  3. EDITORIAL: Integrated non-invasive sensing techniques and geophysical methods for the study and conservation of architectural, archaeological and artistic heritage Integrated non-invasive sensing techniques and geophysical methods for the study and conservation of architectural, archaeological and artistic heritage

    NASA Astrophysics Data System (ADS)

    Masini, N.; Soldovieri, F.

    2011-09-01

    In the last two decades, the use of non-invasive methods for the study and conservation of cultural heritage, from artefacts and historical sites to recent architectural structures, has gained increasing interest. This is due to several reasons: (i) the improvement of performance and information resolution of sensors and devices; (ii) the increasing availability of user-friendly data/image analysis, and processing software and routines; (iii) the ever greater awareness of archaeologists and conservators of the benefits of these technologies, in terms of reduction of costs, time and the risk associated with direct and destructive investigations of archaeological sites (excavation) and monuments (i.e. masonry coring). The choice of diagnostic strategy depends on the spatial and physical characteristics of the cultural objects or sites, the aim of the investigation (knowledge, conservation, restoration) and the issues to be addressed (monitoring, decay assessment, etc). This makes the set up and validation of ad hoc procedures based on data processing and post-processing methods necessary, generally developed to address issues in other fields of application. This methodological perspective based on an integrated and multi-scale approach characterizes the papers of this special issue, which is focused on integrated non-invasive sensing techniques and geophysical methods for the study and conservation of architectural, archaeological and artistic heritage. In particular, attention is given to the advanced application of the synthetic aperture radar (SAR) from the satellite-based platform for deformation monitoring thanks to the innovative differential SAR interferometry (DInSAR) technique; Zeni et al show the significant possibilities of the proposed methodology in achieving a global vision not only of cultural heritage but also of the embedding territory. This collection also deals with the application of non-invasive diagnostics to archaeological prospecting, and

  4. Jesuit Geophysical Observatories

    NASA Astrophysics Data System (ADS)

    Udias, Agustin; Stauder, William

    Jesuits have had ah interest in observing and explaining geophysical phenomena since this religious order, the Society of Jesus, was founded by Ignatius of Loyola in 1540. Three principal factors contributed to this interest: their educational work in colleges and universities, their missionary endeavors to remote lands where they observed interesting and often as yet undocumented natural phenomena, and a network of communication that brought research of other Jesuits readily to their awareness.One of the first and most important Jesuit colleges was the Roman College (today the Gregorian University) founded in 1551 in Rome, which served as a model for many other universities throughout the world. By 1572, Christopher Clavius (1537-1612), professor of mathematics at the Roman College, had already initiated an important tradition of Jesuit research by emphasizing applied mathematics and insisting on the need of serious study of mathematics in the program of studies in the humanities. In 1547 he directed a publication of Euclid's work with commentaries, and published several treatises on mathematics, including Arithmetica Practica [1585], Gnomonicae [1581], and Geometrica Practica [1606]. Clavius was also a Copernican and supported his friend Galileo when he announced the discovery of the satellites of Jupiter.

  5. A ``model`` geophysics program

    SciTech Connect

    Nyquist, J.E.

    1994-03-01

    In 1993, I tested a radio-controlled airplane designed by Jim Walker of Brigham Young University for low-elevation aerial photography. Model-air photography retains most of the advantages of standard aerial photography --- the photographs can be used to detect lineaments, to map roads and buildings, and to construct stereo pairs to measure topography --- and it is far less expensive. Proven applications on the Oak Ridge Reservation include: updating older aerial records to document new construction; using repeated overflights of the same area to capture seasonal changes in vegetation and the effects of major storms; and detecting waste trench boundaries from the color and character of the overlying grass. Aerial photography is only one of many possible applications of radio-controlled aircraft. Currently, I am funded by the Department of Energy`s Office of Technology Development to review the state of the art in microavionics, both military and civilian, to determine ways this emerging technology can be used for environmental site characterization. Being particularly interested in geophysical applications, I am also collaborating with electrical engineers at Oak Ridge National Laboratory to design a model plane that will carry a 3-component flux-gate magnetometer and a global positioning system, which I hope to test in the spring of 1994.

  6. Spectral combination of land-based, airborne, shipborne and altimeter-derived gravity values: examples in Taiwan and Tahiti

    NASA Astrophysics Data System (ADS)

    Hwang, Cheinway

    2016-04-01

    Taiwan and Tahiti are bordered by seas and are islands with mountain ranges up to 4000 m height. The gravity fields here are rough due to the geodynamic processes that create the islands. On and around the two islands, gravity data have been collected by land gravimeters in relative gravity networks (point-wise), by airborne and shipborne (along-track) methods and by transformations from sea surface heights (altimeter-derived). Typically, network-adjusted land gravity values have accuracies of few tens of micro gals and contain the full gravity spectrum. Airborne gravity values are obtained by filtering original one-HZ along-track gravity values collected at varying flight altitudes that are affected by aircraft dynamics, GPS positioning error and gravimeter error. At a 5000-m flight height, along-track airborne gravity has a typical spatial resolution of 4 km and an accuracy of few mgal. Shipborne gravity is similar to airborne gravity, but with higher spatial resolutions because of ship's lower speed. Altimeter-derived gravity has varying spatial resolutions and accuracies, depending on altimeter data, processing method and extent of waveform interference. Using the latest versions of Geosat/GM, ERS-1/GM, ENVISAT, Jason-1/GM, Cryosat-2 and SARAL altimeter data, one can achieve accuracies at few mgal. The synergy of the four kinds of gravity datasets is made by the band-limited least-squares collocation, which best integrates datasets of different accuracies and spatial resolutions. The method uses the best contributions from a DEM, a global gravity model, available gravity datasets to form an optimal gravity grid. We experiment with different optimal spherical harmonic degrees of EGM08 for use around the two islands. For Tahiti, the optimal degree is 1500. New high-resolution gravity and geoid grids are constructed for the two islands and can be used in future geophysical and geodetic studies.

  7. Application of Surface Geophysical Methods, With Emphasis on Magnetic Resonance Soundings, to Characterize the Hydrostratigraphy of the Brazos River Alluvium Aquifer, College Station, Texas, July 2006 - A Pilot Study

    USGS Publications Warehouse

    Shah, Sachin D.; Kress, Wade H.; Legchenko, Anatoly

    2007-01-01

    The U.S. Geological Survey, in cooperation with the Texas Water Development Board, used surface geophysical methods at the Texas A&M University Brazos River Hydrologic Field Research Site near College Station, Texas, in a pilot study, to characterize the hydrostratigraphic properties of the Brazos River alluvium aquifer and determine the effectiveness of the methods to aid in generating an improved ground-water availability model. Three non-invasive surface geophysical methods were used to characterize the electrical stratigraphy and hydraulic properties and to interpret the hydrostratigraphy of the Brazos River alluvium aquifer. Two methods, time-domain electromagnetic (TDEM) soundings and two-dimensional direct-current (2D-DC) resistivity imaging, were used to define the lateral and vertical extent of the Ships clay, the alluvium of the Brazos River alluvium aquifer, and the underlying Yegua Formation. Magnetic resonance sounding (MRS), a recently developed geophysical method, was used to derive estimates of the hydrologic properties including percentage water content and hydraulic conductivity. Results from the geophysics study demonstrated the usefulness of combined TDEM, 2D-DC resistivity, and MRS methods to reduce the need for additional boreholes in areas with data gaps and to provide more accurate information for ground-water availability models. Stratigraphically, the principal finding of this study is the relation between electrical resistivity and the depth and thickness of the subsurface hydrostratigraphic units at the site. TDEM data defined a three-layer electrical stratigraphy corresponding to a conductor-resistor-conductor that represents the hydrostratigraphic units - the Ships clay, the alluvium of the Brazos River alluvium aquifer, and the Yegua Formation. Sharp electrical boundaries occur at about 4 to 6 and 20 to 22 meters below land surface based on the TDEM data and define the geometry of the more resistive Brazos River alluvium aquifer

  8. Retrieval of Atmospheric Temperature from Airborne Microwave Radiometer Observations

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Schreier, Franz; Kenntner, Mareike; Fix, Andreas; Trautmann, Thomas

    2015-06-01

    Atmospheric temperature is a key geophysical parameter associated with fields such as meteorology, climatology, or photochemistry. There exist several techniques to measure temperature profiles. In the case of microwave remote sensing, the vertical temperature profile can be estimated from thermal emission lines of molecular oxygen. The MTP (Microwave Temperature Profiler) instrument is an airborne radiometer developed at the Jet Propulsion Laboratory (JPL), United States. The instrument passively measures natural thermal emission from oxygen lines at 3 frequencies and at a selection of 10 viewing angles (from near zenith to near nadir). MTP has participated in hundreds of flights, including on DLR’s Falcon and HALO aircrafts. These flights have provided data of the vertical temperature distribution from the troposphere to the lower stratosphere with a good temporal and spatial resolution. In this work, we present temperature retrievals based on the Tikhonov-type regularized nonlinear least squares fitting method. In particular, Jacobians (i.e. temperature derivatives) are evaluated by means of automatic differentiation. The retrieval performance from the MTP measurements is analyzed by using synthetic data. Besides, the vertical sensitivity of the temperature retrieval is studied by weighting functions characterizing the sensitivity of the transmission at different frequencies with respect to changes of altitude levels.

  9. Hydrogeophysics at the watershed-scale using airborne electromagnetics

    NASA Astrophysics Data System (ADS)

    Minsley, B. J.; Abraham, J. D.; Bedrosian, P. A.; Cannia, J. C.; Smith, B. D.

    2011-12-01

    Airborne electromagnetic (AEM) surveys provide densely sampled data over large areas (typically several hundred sq. km) that cannot be covered effectively using ground-based methods. AEM data are inverted to infer the distribution of electrical resistivity structures from shallow depths to several hundred meters. These models convey unparalleled details that are used to make inferences about hydrogeologic properties and processes at the watershed-scale. This information is being used in groundwater models that inform water management decisions, to better understand geologic frameworks, and to improve climate change models. We present the results of frequency-domain AEM surveys acquired by the US Geological Survey that have been used for building hydrogeologic frameworks in Nebraska, and understanding permafrost distributions in Alaska. An important aspect of interpreting the AEM data in a hydrogeologic context involves quantifying uncertainty and understanding the constraints on subsurface properties provided by the measured geophysical data. To achieve this, we present a trans-dimensional Bayesian Markov chain Monte Carlo (MCMC) algorithm that samples the distribution of models consistent with the measured data. Assessing the distribution of plausible models, rather than a single 'best-fit' model, provides valuable details about parameter uncertainty and non-uniqueness that leads to a more robust interpretation. In addition, we show how the MCMC algorithm can be used to evaluate the noise level in the measured data as well as errors in the elevation of the AEM system, both of which influence the space of acceptable models.

  10. Integrated geophysical and geological methods to investigate the inner and outer structures of the Quaternary Mýtina maar (W-Bohemia, Czech Republic)

    NASA Astrophysics Data System (ADS)

    Flechsig, Christina; Heinicke, Jens; Mrlina, Jan; Kämpf, Horst; Nickschick, Tobias; Schmidt, Alina; Bayer, Tomáš; Günther, Thomas; Rücker, Carsten; Seidel, Elisabeth; Seidl, Michal

    2015-11-01

    The Mýtina maar is the first known Quaternary maar in the Bohemian Massif. Based on the results of Mrlina et al. (J Volcanol Geother Res 182:97-112, 2009), a multiparametric geophysical (electrical resistivity tomography, gravimetry, magnetometry, seismics) and geological/petrochemical research study had been carried out. The interpretation of the data has provided new information about the inner structure of the volcanic complex: (1) specification of the depth of post-volcanic sedimentary fill (up to ~100 m) and (2) magnetic and resistivity signs of one (or two) hidden volcanic structures interpreted as intrusions or remains of a scoria cone. The findings at the outer structure of the maar incorporate the (1) evidence of circular fracture zones outside the maar, (2) detection and distribution of volcanic ejecta and tephra-fall deposits at the surface, and (3) indications from electrical resistivity tomography and gravity data in the area between the Mýtina maar and Železná hůrka scoria cone, interpreted as a palaeovalley, filled by volcaniclastic rocks, and aligned along the strike line (NW-SE) of the Tachov fault zone. These findings are valuable contributions to extend the knowledge about structure of maar volcanoes in general. Because of ongoing active magmatic processes in the north-east part of the Cheb Basin (ca. 15-30 km north of the investigation area), the Mýtina maar-diatreme volcano and surroundings is a suitable key area for research directed to reconstruction of the palaeovolcanic evolution and assessment of possible future hazard potential in the Bohemian Massif.

  11. Numerical modelling of climate change impacts on freshwater lenses on the North Sea Island of Borkum using hydrological and geophysical methods

    NASA Astrophysics Data System (ADS)

    Sulzbacher, H.; Wiederhold, H.; Siemon, B.; Grinat, M.; Igel, J.; Burschil, T.; Günther, T.; Hinsby, K.

    2012-10-01

    A numerical, density dependent groundwater model is set up for the North Sea Island of Borkum to estimate climate change impacts on coastal aquifers and especially the situation of barrier islands in the Wadden Sea. The database includes information from boreholes, a seismic survey, a helicopter-borne electromagnetic (HEM) survey, monitoring of the freshwater-saltwater boundary by vertical electrode chains in two boreholes, measurements of groundwater table, pumping and slug tests, as well as water samples. Based on a statistical analysis of borehole columns, seismic sections and HEM, a hydrogeological model is set up. The groundwater model is developed using the finite-element programme FEFLOW. The density dependent groundwater model is calibrated on the basis of hydraulic, hydrological and geophysical data, in particular spatial HEM and local monitoring data. Verification runs with the calibrated model show good agreement between measured and computed hydraulic heads. A good agreement is also obtained between measured and computed density or total dissolved solids data for both the entire freshwater lens on a large scale and in the area of the well fields on a small scale. For simulating future changes in this coastal groundwater system until the end of the current century, we use the climate scenario A2, specified by the Intergovernmental Panel on Climate Change and, in particular, the data for the German North Sea coast. Simulation runs show proceeding salinisation with time beneath the well fields of the two waterworks Waterdelle and Ostland. The modelling study shows that the spreading of well fields is an appropriate protection measure against excessive salinisation of the water supply until the end of the current century.

  12. Planetary Geophysics and Tectonics

    NASA Technical Reports Server (NTRS)

    Zuber, Maria

    2005-01-01

    The broad objective of this work is to improve understanding of the internal structures and thermal and stress histories of the solid planets by combining results from analytical and computational modeling, and geophysical data analysis of gravity, topography and tectonic surface structures. During the past year we performed two quite independent studies in the attempt to explain the Mariner 10 magnetic observations of Mercury. In the first we revisited the possibility of crustal remanence by studying the conditions under which one could break symmetry inherent in Runcorn's model of a uniformly magnetized shell to produce a remanent signal with a dipolar form. In the second we applied a thin shell dynamo model to evaluate the range of intensity/structure for which such a planetary configuration can produce a dipole field consistent with Mariner 10 results. In the next full proposal cycle we will: (1) develop numerical and analytical and models of thin shell dynamos to address the possible nature of Mercury s present-day magnetic field and the demise of Mars magnetic field; (2) study the effect of degree-1 mantle convection on a core dynamo as relevant to the early magnetic field of Mars; (3) develop models of how the deep mantles of terrestrial planets are perturbed by large impacts and address the consequences for mantle evolution; (4) study the structure, compensation, state of stress, and viscous relaxation of lunar basins, and address implications for the Moon s state of stress and thermal history by modeling and gravity/topography analysis; and (5) use a three-dimensional viscous relaxation model for a planet with generalized vertical viscosity distribution to study the degree-two components of the Moon's topography and gravity fields to constrain the primordial stress state and spatial heterogeneity of the crust and mantle.

  13. Compression scheme for geophysical electromagnetic inversions

    NASA Astrophysics Data System (ADS)

    Abubakar, A.

    2014-12-01

    We have developed a model-compression scheme for improving the efficiency of the regularized Gauss-Newton inversion algorithm for geophysical electromagnetic applications. In this scheme, the unknown model parameters (the conductivity/resistivity distribution) are represented in terms of a basis such as Fourier and wavelet (Haar and Daubechies). By applying a truncation criterion, the model may then be approximated by a reduced number of basis functions, which is usually much less than the number of the model parameters. Further, because the geophysical electromagnetic measurements have low resolution, it is sufficient for inversion to only keep the low-spatial frequency part of the image. This model-compression scheme accelerates the computational time and also reduces the memory usage of the Gauss-Newton method. We are able to significantly reduce the algorithm computational complexity without compromising the quality of the inverted models.

  14. NASA Airborne Science Program: NASA Stratospheric Platforms

    NASA Technical Reports Server (NTRS)

    Curry, Robert E.

    2010-01-01

    The National Aeronautics and Space Administration conducts a wide variety of remote sensing projects using several unique aircraft platforms. These vehicles have been selected and modified to provide capabilities that are particularly important for geophysical research, in particular, routine access to very high altitudes, long range, long endurance, precise trajectory control, and the payload capacity to operate multiple, diverse instruments concurrently. While the NASA program has been in operation for over 30 years, new aircraft and technological advances that will expand the capabilities for airborne observation are continually being assessed and implemented. This presentation will review the current state of NASA's science platforms, recent improvements and new missions concepts as well as provide a survey of emerging technologies unmanned aerial vehicles for long duration observations (Global Hawk and Predator). Applications of information technology that allow more efficient use of flight time and the ability to rapidly reconfigure systems for different mission objectives are addressed.

  15. Airborne gravimetry, altimetry, and GPS navigation errors

    NASA Technical Reports Server (NTRS)

    Colombo, Oscar L.

    1992-01-01

    Proper interpretation of airborne gravimetry and altimetry requires good knowledge of aircraft trajectory. Recent advances in precise navigation with differential GPS have made it possible to measure gravity from the air with accuracies of a few milligals, and to obtain altimeter profiles of terrain or sea surface correct to one decimeter. These developments are opening otherwise inaccessible regions to detailed geophysical mapping. Navigation with GPS presents some problems that grow worse with increasing distance from a fixed receiver: the effect of errors in tropospheric refraction correction, GPS ephemerides, and the coordinates of the fixed receivers. Ionospheric refraction and orbit error complicate ambiguity resolution. Optimal navigation should treat all error sources as unknowns, together with the instantaneous vehicle position. To do so, fast and reliable numerical techniques are needed: efficient and stable Kalman filter-smoother algorithms, together with data compression and, sometimes, the use of simplified dynamics.

  16. Using geophysics to characterize levee stability

    NASA Astrophysics Data System (ADS)

    Dalton, Laura M.

    Shallow slough slides have occurred along the river side slope of Mississippi River Levees for over sixty years. Shallow slough slides also occur along smaller levees that protect tributaries of the Mississippi River. This investigation takes place along a section of the Coldwater River Levee, a tributary levee of the Mississippi River. Field observation, soil samples, and geophysical data were collected at two field sites located on the border of Tate and Tunica County, MS. The first site consists of a developed shallow slough slide that had occurred that has not yet been repaired and the second site is a potential slide area. Electromagnetic induction and electrical resistivity tomography were the geophysical methods used to define subsurface conditions that make a levee vulnerable to failure. These electrical methods are sensitive to the electrical conductivity of the soil and therefore depend upon: soil moisture, clay content, pore size distribution as well as larger scale structures at depth such as cracks and fissures. These same physical properties of the soil are also important to assessing the vulnerability of a levee to slough slides. Soil tests and field observations were also implemented in this investigation to describe and classify the soil composition of the levee material. The problem of slough slide occurrence can potentially be reduced if vulnerabilities are located with the help of geophysical techniques.

  17. Enumerating Spore-Forming Bacteria Airborne with Particles

    NASA Technical Reports Server (NTRS)

    Lin, Ying; Barengoltz, Jack

    2006-01-01

    A laboratory method has been conceived to enable the enumeration of (1) Cultivable bacteria and bacterial spores that are, variously, airborne by themselves or carried by, parts of, or otherwise associated with, other airborne particles; and (2) Spore-forming bacteria among all of the aforementioned cultivable microbes.

  18. Detection and enumeration of airborne biocontaminants.

    PubMed

    Stetzenbach, Linda D; Buttner, Mark P; Cruz, Patricia

    2004-06-01

    The sampling and analysis of airborne microorganisms has received attention in recent years owing to concerns with mold contamination in indoor environments and the threat of bioterrorism. Traditionally, the detection and enumeration of airborne microorganisms has been conducted using light microscopy and/or culture-based methods; however, these analyses are time-consuming, laborious, subjective and lack sensitivity and specificity. The use of molecular methods, such as quantitative polymerase chain reaction amplification, can enhance monitoring strategies by increasing sensitivity and specificity, while decreasing the time required for analysis.

  19. Indoor vs Outdoor Geophysics

    NASA Astrophysics Data System (ADS)

    Liebermann, R. C.

    2009-05-01

    Research in mineral physics is essential for interpreting observational data from many other disciplines in the Earth Sciences, from geodynamics to seismology to geochemistry to petrology to geomagnetism to planetary science, and extending also to materials science and climate studies. The field of high-pressure mineral physics is highly interdisciplinary. Mineral physicists do not always study minerals nor use only physics; they study the science of materials which comprise the Earth and other planets and employ the concepts and techniques from chemistry, physics, materials science, and even biology. Observations from geochemistry and geophysics studies lead to the development of petrologic, seismic and geodynamical models of the Earth's deep interior. The goal of mineral physics is to interpret such models in terms of variations of pressure, temperature, mineralogy/crystallography, and/or chemical composition with depth. The discovery in 2004 of the post-perovskite phase of MgSiO3 at pressures in excess of 120 GPa and high temperatures has led to an explosion of both complimentary experimental and theoretical work in mineral physics and remarkable synergy between mineral physics and the disciplines of seismology, geodynamics and geochemistry. Similarly, the observation of high-spin to low-spin transitions in Fe-bearing minerals at high pressures has important implications for the lower mantle of the Earth. We focus in this talk on the use of experimental physical acoustics to conduct "indoor seismology" experiments to measure sound wave velocities of minerals under the pressure and temperature conditions of the Earth's mantle. This field of research has a long history dating back at least to the studies of Francis Birch in the 1950s. The techniques include ultrasonic interferometry, resonant ultrasound spectroscopy, and Brillouin spectroscopy. Many of these physical acoustic experiments are now performed in conjunction with synchrotron X-radiation sources at

  20. Geophysical applications for levee assessment

    NASA Astrophysics Data System (ADS)

    Chlaib, Hussein Khalefa

    Levees are important engineering structures that build along the rivers to protect the human lives and shield the communities as well as agriculture lands from the high water level events. Animal burrows, subsurface cavities, and low density (high permeability) zones are weakness features within the levee body that increase its risk of failure. To prevent such failure, continuous monitoring of the structure integrity and early detection of the weakness features must be conducted. Application of Ground Penetrating Radar (GPR) and Capacitively Coupled Resistivity (CCR) methods were found to be very effective in assessing the levees and detect zones of weakness within the levee body. GPR was implemented using multi-frequency antennas (200, 400, and 900 MHz) with survey cart/wheel and survey vehicle. The (CCR) method was applied by using a single transmitter and three receivers. Studying the capability and the effectiveness of these methods in levee monitoring, subsurface weakness feature detection, and studying the structure integrity of levees were the main tasks of this dissertation. A set of laboratory experiments was conducted at the Geophysics Laboratory of the University of Arkansas at Little Rock (UALR) to analyze the polarity change in GPR signals in the presence of subsurface voids and water-filled cavities. Also three full scale field expeditions at the Big Dam Bridge (BDB) Levee, Lollie Levee, and Helena Levee in Arkansas were conducted using the GPR technique. This technique was effective in detecting empty, water, and clay filled cavities as well as small scale animal burrows (small rodents). The geophysical work at BDB and Lollie Levees expressed intensive subsurface anomalies which might decrease their integrity while the Helena Levee shows less subsurface anomalies. The compaction of levee material is a key factor affecting piping phenomenon. The structural integrity of the levee partially depends on the density/compaction of the soil layers. A

  1. Airborne data acquisition techniques

    SciTech Connect

    Arro, A.A.

    1980-01-01

    The introduction of standards on acceptable procedures for assessing building heat loss has created a dilemma for the contractor performing airborne thermographic surveys. These standards impose specifications on instrumentation, data acquisition, recording, interpretation, and presentation. Under the standard, the contractor has both the obligation of compliance and the requirement of offering his services at a reasonable price. This paper discusses the various aspects of data acquisition for airborne thermographic surveys and various techniques to reduce the costs of this operation. These techniques include the calculation of flight parameters for economical data acquisition, the selection and use of maps for mission planning, and the use of meteorological forecasts for flight scheduling and the actual execution of the mission. The proper consideration of these factors will result in a cost effective data acquisition and will place the contractor in a very competitive position in offering airborne thermographic survey services.

  2. Biological monitoring of airborne pollution

    SciTech Connect

    Ditz, D.W. )

    1990-01-01

    Common plants such as grasses, mosses, and even goldenrod may turn out to have a new high-tech role as monitors of airborne pollution from solid waste incinerators. Certain plants that respond to specific pollutants can provide continuous surveillance of air quality over long periods of time: they are bio-indicators. Other species accumulate pollutants and can serve as sensitive indicators of pollutants and of food-chain contamination: they are bio-accumulators. Through creative use of these properties, biological monitoring can provide information that cannot be obtained by current methods such as stack testing.

  3. Airborne oceanographic lidar system

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Specifications and preliminary design of an Airborne Oceanographic Lidar (AOL) system, which is to be constructed for installation and used on a NASA Wallops Flight Center (WFC) C-54 research aircraft, are reported. The AOL system is to provide an airborne facility for use by various government agencies to demonstrate the utility and practicality of hardware of this type in the wide area collection of oceanographic data on an operational basis. System measurement and performance requirements are presented, followed by a description of the conceptual system approach and the considerations attendant to its development. System performance calculations are addressed, and the system specifications and preliminary design are presented and discussed.

  4. Airborne rain mapping radar

    NASA Technical Reports Server (NTRS)

    Wilson, W. J.; Parks, G. S.; Li, F. K.; Im, K. E.; Howard, R. J.

    1988-01-01

    An airborne scanning radar system for remote rain mapping is described. The airborne rain mapping radar is composed of two radar frequency channels at 13.8 and 24.1 GHz. The radar is proposed to scan its antenna beam over + or - 20 deg from the antenna boresight; have a swath width of 7 km; a horizontal spatial resolution at nadir of about 500 m; and a range resolution of 120 m. The radar is designed to be applicable for retrieving rainfall rates from 0.1-60 mm/hr at the earth's surface, and for measuring linear polarization signatures and raindrop's fall velocity.

  5. Integrating geophysics and geochemistry to evaluate coalbed natural gas produced water disposal, Powder River Basin, Wyoming

    NASA Astrophysics Data System (ADS)

    Lipinski, Brian Andrew

    Production of methane from thick, extensive coalbeds in the Powder River Basin of Wyoming has created water management issues. More than 4.1 billion barrels of water have been produced with coalbed natural gas (CBNG) since 1997. Infiltration impoundments, which are the principal method used to dispose CBNG water, contribute to the recharge of underlying aquifers. Airborne electromagnetic surveys of an alluvial aquifer that has been receiving CBNG water effluent through infiltration impoundments since 2001 reveal produced water plumes within these aquifers and also provide insight into geomorphologic controls on resultant salinity levels. Geochemical data from the same aquifer reveal that CBNG water enriched in sodium and bicarbonate infiltrates and mixes with sodium-calcium-sulfate type alluvial groundwater, which subsequently may have migrated into the Powder River. The highly sodic produced water undergoes cation exchange reactions with native alluvial sediments as it infiltrates, exchanging sodium from solution for calcium and magnesium on montmorillonite clays. The reaction may ultimately reduce sediment permeability by clay dispersion. Strontium isotope data from CBNG wells discharging water into these impoundments indicate that the Anderson coalbed of the Fort Union Formation is dewatered due to production. Geophysical methods provide a broad-scale tool to monitor CBNG water disposal especially in areas where field based investigations are logistically prohibitive, but geochemical data are needed to reveal subsurface processes undetectable by geophysical techniques. The results of this research show that: (1) CBNG impoundments should not be located near streams because they can alter the surrounding hydraulic potential field forcing saline alluvial groundwater and eventually CBNG water into the stream, (2) point bars are poor impoundment locations because they are essentially in direct hydraulic communication with the associated stream and because plants

  6. NASA Airborne Lidar July 1991

    Atmospheric Science Data Center

    2016-05-26

    NASA Airborne Lidar July 1991 Data from the 1991 NASA Langley Airborne Lidar flights following the eruption of Pinatubo in July ... and Osborn [1992a, 1992b]. Project Title:  NASA Airborne Lidar Discipline:  Field Campaigns ...

  7. NASA Airborne Lidar May 1992

    Atmospheric Science Data Center

    2016-05-26

    NASA Airborne Lidar May 1992 An airborne Nd:YAG (532 nm) lidar was operated by the NASA Langley Research Center about a year following the June 1991 eruption of ... Osborn [1992a, 1992b].  Project Title:  NASA Airborne Lidar Discipline:  Field Campaigns ...

  8. SAGE celebrates 25 years of learning geophysics by doing geophysics

    USGS Publications Warehouse

    Jiracek, G.R.; Baldridge, W.S.; Sussman, A.J.; Biehler, S.; Braile, L.W.; Ferguson, J.F.; Gilpin, B.E.; McPhee, D.K.; Pellerin, L.

    2008-01-01

    The increasing world demand and record-high costs for energy and mineral resources, along with the attendant environmental and climate concerns, have escalated the need for trained geophysicists to unprecedented levels. This is not only a national need; it's a critical global need. As Earth scientists and educators we must seriously ask if our geophysics pipeline can adequately address this crisis. One program that has helped to answer this question in the affirmative for 25 years is SAGE (Summer of Applied Geophysical Experience). SAGE continues to develop with new faculty, new collaborations, and additional ways to support student participation during and after SAGE. ?? 2008 Society of Exploration Geophysicists.

  9. Geophysical mapping of solution and collapse sinkholes

    NASA Astrophysics Data System (ADS)

    Kaufmann, Georg

    2014-12-01

    Karst rocks such as limestone, dolomite, anhydrite, gypsum, or salt can be dissolved physically by water or chemically by water enriched with carbon dioxide. The dissolution is driven by water flowing through the karst aquifer and either occurs along fractures and bedding partings in telogenetic rocks, or within the primary interconnected pore space in eogenetic rocks. The enlargement of either fractures or pores by dissolution creates a large secondary porosity typical of soluble rocks, which is often very heterogenously distributed and results in preferential flow paths in the sub-surface, with cavities as large-scale end members of the sub-surface voids. Once the sub-surface voids enlarged by dissolution grow to a certain size, the overburden rock can become unstable and voids and caves can collapse. Depending on the type of overburden, the collapse initiated at depth may propagate towards the surface and finally results at the surface as collapse sinkholes and tiangkengs on the very large scale. We present results from geophysical surveys over existing karst structures based on gravimetric, electrical, and geomagnetical methods. We have chosen two types of sinkholes, solution and collapse sinkholes, to capture and compare the geophysical signals resulting from these karst structures. We compare and discuss our geophysical survey results with simplified theoretical models describing the evolution of the karst structure, and we derive three-dimensional structural models of the current situation for the different locations with our numerical tool PREDICTOR.

  10. Geophysical mapping of solution and collapse dolines

    NASA Astrophysics Data System (ADS)

    Kaufmann, Georg

    2014-05-01

    Karst rocks such as limestone, dolomite, anhydrite, gypsum, or salt can be dissolved physically by water or chemically by water enriched with carbon dioxide. The dissolution driven by water flowing through the karst aquifer either occurs along fractures and bedding partings in telogenetic rocks, or within the primary interconnected pore space in eogenetic rocks. The enlargement of either fractures or pores by dissolution creates a large secondary porosity typical for karst rocks, which is often very heterogenously distributed and results in preferential flow pathes in the sub-surface, with cavities as large-scale end members of the sub-surface voids. Once the sub-surface voids enlarged by dissolution grow to a certain size, the overburden rock can become instable and voids and caves can collapse. Depending of the type of overburden, the collapse initiated at depth propagates towards the surface and finally results in a collapse structure, such as collapse dolines, sinkholes, and tiangkengs on the very large scale. We present results from geophysical surveys over existing karst structures based on gravimetric, electrical, and geomagnetical methods. We have chosen two types of dolines, solution and collapse dolines, to capture and compare the geophysical signals resulting from these karst structures. We compare and discuss our geophysical survey results with simplified theoretical models describing the evolution of the karst structure and three-dimensional structural models for the current situation derived for the different locations.

  11. Geophysical investigation, Salmon Site, Lamar County, Mississippi

    SciTech Connect

    1995-02-01

    Geophysical surveys were conducted in 1992 and 1993 on 21 sites at the Salmon Site (SS) located in Lamar County, Mississippi. The studies are part of the Remedial Investigation/Feasibility Study (RI/FS) being conducted by IT Corporation for the U.S. Department of Energy (DOE). During the 1960s, two nuclear devices and two chemical tests were detonated 826 meters (in) (2710 feet [ft]) below the ground surface in the salt dome underlying the SS. These tests were part of the Vela Uniform Program conducted to improve the United States capability to detect, identify, and locate underground nuclear detonations. The RI/FS is being conducted to determine if any contamination is migrating from the underground shot cavity in the salt dome and if there is any residual contamination in the near surface mud and debris disposal pits used during the testing activities. The objective of the surface geophysical surveys was to locate buried debris, disposal pits, and abandoned mud pits that may be present at the site. This information will then be used to identify the locations for test pits, cone penetrometer tests, and drill hole/monitor well installation. The disposal pits were used during the operation of the test site in the 1960s. Vertical magnetic gradient (magnetic gradient), electromagnetic (EM) conductivity, and ground-penetrating radar (GPR) surveys were used to accomplish these objectives. A description of the equipment used and a theoretical discussion of the geophysical methods are presented Appendix A. Because of the large number of figures relative to the number of pages of text, the geophysical grid-location maps, the contour maps of the magnetic-gradient data, the contour maps of the EM conductivity data, and the GPR traverse location maps are located in Appendix B, Tabs I through 22. In addition, selected GPR records are located in Appendix C.

  12. Active airborne contamination control using electrophoresis

    SciTech Connect

    Veatch, B.D.

    1994-06-01

    In spite of our best efforts, radioactive airborne contamination continues to be a formidable problem at many of the Department of Energy (DOE) weapons complex sites. For workers that must enter areas with high levels of airborne contamination, personnel protective equipment (PPE) can become highly restrictive, greatly diminishing productivity. Rather than require even more restrictive PPE for personnel in some situations, the Rocky Flats Plant (RFP) is actively researching and developing methods to aggressively combat airborne contamination hazards using electrophoretic technology. With appropriate equipment, airborne particulates can be effectively removed and collected for disposal in one simple process. The equipment needed to implement electrophoresis is relatively inexpensive, highly reliable, and very compact. Once airborne contamination levels are reduced, less PPE is required and a significant cost savings may be realized through decreased waste and maximized productivity. Preliminary ``cold,`` or non-radioactive, testing results at the RFP have shown the technology to be effective on a reasonable scale, with several potential benefits and an abundance of applications.

  13. Airborne laser communication technology and flight test

    NASA Astrophysics Data System (ADS)

    Meng, Li-xin; Zhang, Li-zhong; Li, Xiao-ming; Li, Ying-chao; Jiang, Hui-lin

    2015-11-01

    Reconnaissance aircraft is an important node of the space-air-ground integrated information network, on which equipped with a large number of high-resolution surveillance equipment, and need high speed communications equipment to transmit detected information in real time. Currently RF communication methods cannot meet the needs of communication bandwidth. Wireless laser communication has outstanding advantages high speed, high capacity, security, etc., is an important means to solve the high-speed information transmission of airborne platforms. In this paper, detailed analysis of how the system works, the system components, work processes, link power and the key technologies of airborne laser communication were discussed. On this basis, a prototype airborne laser communications was developed, and high-speed, long-distance communications tests were carried out between the two fixed-wing aircraft, and the airborne precision aiming, atmospheric laser communication impacts on laser communication were tested. The experiments ultimately realize that, the communication distance is 144km, the communication rate is 2.5Gbps. The Airborne laser communication experiments provide technical basis for the application of the conversion equipment.

  14. Urban greenness influences airborne bacterial community composition.

    PubMed

    Mhuireach, Gwynne; Johnson, Bart R; Altrichter, Adam E; Ladau, Joshua; Meadow, James F; Pollard, Katherine S; Green, Jessica L

    2016-11-15

    Urban green space provides health benefits for city dwellers, and new evidence suggests that microorganisms associated with soil and vegetation could play a role. While airborne microorganisms are ubiquitous in urban areas, the influence of nearby vegetation on airborne microbial communities remains poorly understood. We examined airborne microbial communities in parks and parking lots in Eugene, Oregon, using high-throughput sequencing of the bacterial 16S rRNA gene on the Illumina MiSeq platform to identify bacterial taxa, and GIS to measure vegetation cover in buffer zones of different diameters. Our goal was to explore variation among highly vegetated (parks) versus non-vegetated (parking lots) urban environments. A secondary objective was to evaluate passive versus active collection methods for outdoor airborne microbial sampling. Airborne bacterial communities from five parks were different from those of five parking lots (p=0.023), although alpha diversity was similar. Direct gradient analysis showed that the proportion of vegetated area within a 50m radius of the sampling station explained 15% of the variation in bacterial community composition. A number of key taxa, including several Acidobacteriaceae were substantially more abundant in parks, while parking lots had higher relative abundance of Acetobacteraceae. Parks had greater beta diversity than parking lots, i.e. individual parks were characterized by unique bacterial signatures, whereas parking lot communities tended to be similar to each other. Although parks and parking lots were selected to form pairs of nearby sites, spatial proximity did not appear to affect compositional similarity. Our results also showed that passive and active collection methods gave comparable results, indicating the "settling dish" method is effective for outdoor airborne sampling. This work sets a foundation for understanding how urban vegetation may impact microbial communities, with potential implications for designing

  15. Urban greenness influences airborne bacterial community composition.

    PubMed

    Mhuireach, Gwynne; Johnson, Bart R; Altrichter, Adam E; Ladau, Joshua; Meadow, James F; Pollard, Katherine S; Green, Jessica L

    2016-11-15

    Urban green space provides health benefits for city dwellers, and new evidence suggests that microorganisms associated with soil and vegetation could play a role. While airborne microorganisms are ubiquitous in urban areas, the influence of nearby vegetation on airborne microbial communities remains poorly understood. We examined airborne microbial communities in parks and parking lots in Eugene, Oregon, using high-throughput sequencing of the bacterial 16S rRNA gene on the Illumina MiSeq platform to identify bacterial taxa, and GIS to measure vegetation cover in buffer zones of different diameters. Our goal was to explore variation among highly vegetated (parks) versus non-vegetated (parking lots) urban environments. A secondary objective was to evaluate passive versus active collection methods for outdoor airborne microbial sampling. Airborne bacterial communities from five parks were different from those of five parking lots (p=0.023), although alpha diversity was similar. Direct gradient analysis showed that the proportion of vegetated area within a 50m radius of the sampling station explained 15% of the variation in bacterial community composition. A number of key taxa, including several Acidobacteriaceae were substantially more abundant in parks, while parking lots had higher relative abundance of Acetobacteraceae. Parks had greater beta diversity than parking lots, i.e. individual parks were characterized by unique bacterial signatures, whereas parking lot communities tended to be similar to each other. Although parks and parking lots were selected to form pairs of nearby sites, spatial proximity did not appear to affect compositional similarity. Our results also showed that passive and active collection methods gave comparable results, indicating the "settling dish" method is effective for outdoor airborne sampling. This work sets a foundation for understanding how urban vegetation may impact microbial communities, with potential implications for designing

  16. Object Storage for Geophysical Data

    NASA Astrophysics Data System (ADS)

    Habermann, T.; Readey, J.

    2015-12-01

    Object storage systems (such as Amazon S3 or Ceph) have been shown to be cost-effective and highly scalable for data repositories in the Petabyte range and larger. However traditionally data storage used for geophysical software systems has centered on file-based systems and libraries such as NetCDF and HDF5. In this session we'll discuss the advantages and challenges of moving to an object store-based model for geophysical data. We'll review a proposed model for a geophysical data service that provides an API-compatible library for traditional NetCDF and HDF5 applications while providing high scalability and performance. One further advantage of this approach is that any dataset or dataset selection can be referenced as a URI. By using versioning, the data the URI references can be guaranteed to be unmodified, thus enabling reproducibility of referenced data.

  17. Airborne Fraunhofer Line Discriminator

    NASA Technical Reports Server (NTRS)

    Gabriel, F. C.; Markle, D. A.

    1969-01-01

    Airborne Fraunhofer Line Discriminator enables prospecting for fluorescent materials, hydrography with fluorescent dyes, and plant studies based on fluorescence of chlorophyll. Optical unit design is the coincidence of Fraunhofer lines in the solar spectrum occurring at the characteristic wavelengths of some fluorescent materials.

  18. Recognizing Airborne Hazards.

    ERIC Educational Resources Information Center

    Schneider, Christian M.

    1990-01-01

    The heating, ventilating, and air conditioning (HVAC) systems in older buildings often do not adequately handle air-borne contaminants. Outlines a three-stage Indoor Air Quality (IAQ) assessment and describes a case in point at a Pittsburgh, Pennsylvania, school. (MLF)

  19. Airborne asbestos in buildings.

    PubMed

    Lee, R J; Van Orden, D R

    2008-03-01

    The concentration of airborne asbestos in buildings nationwide is reported in this study. A total of 3978 indoor samples from 752 buildings, representing nearly 32 man-years of sampling, have been analyzed by transmission electron microscopy. The buildings that were surveyed were the subject of litigation related to suits alleging the general building occupants were exposed to a potential health hazard as a result the presence of asbestos-containing materials (ACM). The average concentration of all airborne asbestos structures was 0.01structures/ml (s/ml) and the average concentration of airborne asbestos > or = 5microm long was 0.00012fibers/ml (f/ml). For all samples, 99.9% of the samples were <0.01 f/ml for fibers longer than 5microm; no building averaged above 0.004f/ml for fibers longer than 5microm. No asbestos was detected in 27% of the buildings and in 90% of the buildings no asbestos was detected that would have been seen optically (> or = 5microm long and > or = 0.25microm wide). Background outdoor concentrations have been reported at 0.0003f/ml > or = 5microm. These results indicate that in-place ACM does not result in elevated airborne asbestos in building atmospheres approaching regulatory levels and that it does not result in a significantly increased risk to building occupants.

  20. Initial Retrieval Validation from the Joint Airborne IASI Validation Experiment (JAIVEx)

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Liu, Xu; Smith, WIlliam L.; Larar, Allen M.; Taylor, Jonathan P.; Revercomb, Henry E.; Mango, Stephen A.; Schluessel, Peter; Calbet, Xavier

    2007-01-01

    The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite, but also included a strong component focusing on validation of the Atmospheric InfraRed Sounder (AIRS) aboard the AQUA satellite. The cross validation of IASI and AIRS is important for the joint use of their data in the global Numerical Weather Prediction process. Initial inter-comparisons of geophysical products have been conducted from different aspects, such as using different measurements from airborne ultraspectral Fourier transform spectrometers (specifically, the NPOESS Airborne Sounder Testbed Interferometer (NAST-I) and the Scanning-High resolution Interferometer Sounder (S-HIS) aboard the NASA WB-57 aircraft), UK Facility for Airborne Atmospheric Measurements (FAAM) BAe146-301 aircraft insitu instruments, dedicated dropsondes, radiosondes, and ground based Raman Lidar. An overview of the JAIVEx retrieval validation plan and some initial results of this field campaign are presented.

  1. Regional scale groundwater resource assessment in the Australian outback - Geophysics is the only way.

    NASA Astrophysics Data System (ADS)

    Munday, T. J.; Davis, A. C.; Gilfedder, M.; Annetts, D.

    2015-12-01

    Resource development, whether in agriculture, mining and/or energy, is set to have significant consequences for the groundwater resources of Australia in the short to medium term. These industry sectors are of significant economic value to the country and consequently their support remains a priority for State and Federal Governments alike. The scale of potential developments facilitated in large part by the Government Programs, like the West Australian (WA) Government's "Water for Food" program, and the South Australian's Government's PACE program, will result in an increase in infrastructure requirements, including access to water resources and Aboriginal lands to support these developments. However, the increased demand for water, particularly groundwater, is likely to be compromised by the limited information we have about these resources. This is particularly so for remote parts of the country which are targeted as primary development areas. There is a recognised need to expand this knowledge so that water availability is not a limiting factor to development. Governments of all persuasions have therefore adopted geophysical technologies, particularly airborne electromagnetics (AEM), as a basis for extending the hydrogeological knowledge of data poor areas. In WA, the State Government has employed regional-scale AEM surveys as a basis for defining groundwater resources to support mining, regional agricultural developments whilst aiming to safeguard regional population centres, and environmental assets. A similar approach is being employed in South Australia. These surveys are being used to underpin conceptual hydrogeological frameworks, define basin-scale hydrogeological models, delimit the extent of saltwater intrusion in coastal areas, and to determine the groundwater resource potential of remote alluvial systems aimed at supporting new, irrigation-based, agricultural developments in arid parts of the Australian outback. In the absence of conventional

  2. Photoreactivation in Airborne Mycobacterium parafortuitum

    PubMed Central

    Peccia, Jordan; Hernandez, Mark

    2001-01-01

    Photoreactivation was observed in airborne Mycobacterium parafortuitum exposed concurrently to UV radiation (254 nm) and visible light. Photoreactivation rates of airborne cells increased with increasing relative humidity (RH) and decreased with increasing UV dose. Under a constant UV dose with visible light absent, the UV inactivation rate of airborne M. parafortuitum cells decreased by a factor of 4 as RH increased from 40 to 95%; however, under identical conditions with visible light present, the UV inactivation rate of airborne cells decreased only by a factor of 2. When irradiated in the absence of visible light, cellular cyclobutane thymine dimer content of UV-irradiated airborne M. parafortuitum and Serratia marcescens increased in response to RH increases. Results suggest that, unlike in waterborne bacteria, cyclobutane thymine dimers are not the most significant form of UV-induced DNA damage incurred by airborne bacteria and that the distribution of DNA photoproducts incorporated into UV-irradiated airborne cells is a function of RH. PMID:11526027

  3. GTE: a new FFT based software to compute terrain correction on airborne gravity surveys in spherical approximation.

    NASA Astrophysics Data System (ADS)

    Capponi, Martina; Sampietro, Daniele; Sansò, Fernando

    2016-04-01

    The computation of the vertical attraction due to the topographic masses (Terrain Correction) is still a matter of study both in geodetic as well as in geophysical applications. In fact it is required in high precision geoid estimation by the remove-restore technique and it is used to isolate the gravitational effect of anomalous masses in geophysical exploration. This topographical effect can be evaluated from the knowledge of a Digital Terrain Model in different ways: e.g. by means of numerical integration, by prisms, tesseroids, polyedra or Fast Fourier Transform (FFT) techniques. The increasing resolution of recently developed digital terrain models, the increasing number of observation points due to extensive use of airborne gravimetry and the increasing accuracy of gravity data represents nowadays major issues for the terrain correction computation. Classical methods such as prism or point masses approximations are indeed too slow while Fourier based techniques are usually too approximate for the required accuracy. In this work a new software, called Gravity Terrain Effects (GTE), developed in order to guarantee high accuracy and fast computation of terrain corrections is presented. GTE has been thought expressly for geophysical applications allowing the computation not only of the effect of topographic and bathymetric masses but also those due to sedimentary layers or to the Earth crust-mantle discontinuity (the so called Moho). In the present contribution we summarize the basic theory of the software and its practical implementation. Basically the GTE software is based on a new algorithm which, by exploiting the properties of the Fast Fourier Transform, allows to quickly compute the terrain correction, in spherical approximation, at ground or airborne level. Some tests to prove its performances are also described showing GTE capability to compute high accurate terrain corrections in a very short time. Results obtained for a real airborne survey with GTE

  4. Geophysics applications in critical zone science: emerging topics.

    NASA Astrophysics Data System (ADS)

    Pachepsky, Y. A.; Martinez, G.; Guber, A.; Walthall, C. L.; Vereecken, H.

    2012-12-01

    and ecological variables are bound to vary with support and spacing. The mismatch between supports of soil measurement and geophysical footprints has been acknowledged but not resolved. Search is under way for metrics to compress dense geophysical data to be analyzed jointly with the sparser ecological information in space and time. Segmentation methods are needed that are specific to the data generated in critical zone geophysics. The geophysical data presentation will remain an art to some extent, and therefore interaction between form and content in this presentation is of interest. Currently modeling abandons the role of consumer of the structural information about the flow and transport domain, and becomes an organic part of the retrieval process. Much more is done in aquifer modeling than in modeling of variably saturated domains. Model abstraction and multimodeling can provide the functional evaluation of the retrieval components, such as segmentation, and results. The gap remains between the rich information content of the geophysical data and complexity of models in which the retrieval results are used. Field critical zone research is hardly possible without the input from geophysics. It is critical to achieve a tighter coupling of geophysical tools with other tools used in diagnostics, monitoring, and prediction of critical zone processes.

  5. [Characterizing Beijing's Airborne Bacterial Communities in PM2.5 and PM1 Samples During Haze Pollution Episodes Using 16S rRNA Gene Analysis Method].

    PubMed

    Wang, Bu-ying; Lang, Ji-dong; Zhang, Li-na; Fang, Jian-huo; Cao, Chen; Hao, Ji-ming; Zhu, Ting; Tian, Geng; Jiang, Jing-kun

    2015-08-01

    During 8th-14th Jan., 2013, severe particulate matter (PM) pollution episodes happened in Beijing. These air pollution events lead to high risks for public health. In addition to various PM chemical compositions, biological components in the air may also impose threaten. Little is known about airborne microbial community in such severe air pollution conditions. PM2.5 and PM10 samples were collected during that 7-day pollution period. The 16S rRNA gene V3 amplification and the MiSeq sequencing were performed for analyzing these samples. It is found that there is no significant difference at phylum level for PM2.5 bacterial communities during that 7-day pollution period both at phylum and at genus level. At genus level, Arthrobacter and Frankia are the major airborne microbes presented in Beijing winter.samples. At genus level, there are 39 common genera (combined by first 50 genera bacterial of the two analysis) between the 16S rRNA gene analysis and those are found by Metagenomic analysis on the same PM samples. Frankia and Paracoccus are relatively more abundant in 16S rRNA gene data, while Kocuria and Geodermatophilus are relatively more abundant in Meta-data. PM10 bacterial communities are similar to those of PM2.5 with some noticeable differences, i.e., at phylum level, more Firmicutes and less Actinobacteria present in PM10 samples than in PM2.5 samples, while at genus level, more Clostridium presents in PM10 samples. The findings in Beijing were compared with three 16S rRNA gene studies in other countries. Although the sampling locations and times are different from each other, compositions of bacterial community are similar for those sampled at the ground atmosphere. Airborne microbial communities near the ground surface are different from those sampled in the upper troposphere. PMID:26591997

  6. [Characterizing Beijing's Airborne Bacterial Communities in PM2.5 and PM1 Samples During Haze Pollution Episodes Using 16S rRNA Gene Analysis Method].

    PubMed

    Wang, Bu-ying; Lang, Ji-dong; Zhang, Li-na; Fang, Jian-huo; Cao, Chen; Hao, Ji-ming; Zhu, Ting; Tian, Geng; Jiang, Jing-kun

    2015-08-01

    During 8th-14th Jan., 2013, severe particulate matter (PM) pollution episodes happened in Beijing. These air pollution events lead to high risks for public health. In addition to various PM chemical compositions, biological components in the air may also impose threaten. Little is known about airborne microbial community in such severe air pollution conditions. PM2.5 and PM10 samples were collected during that 7-day pollution period. The 16S rRNA gene V3 amplification and the MiSeq sequencing were performed for analyzing these samples. It is found that there is no significant difference at phylum level for PM2.5 bacterial communities during that 7-day pollution period both at phylum and at genus level. At genus level, Arthrobacter and Frankia are the major airborne microbes presented in Beijing winter.samples. At genus level, there are 39 common genera (combined by first 50 genera bacterial of the two analysis) between the 16S rRNA gene analysis and those are found by Metagenomic analysis on the same PM samples. Frankia and Paracoccus are relatively more abundant in 16S rRNA gene data, while Kocuria and Geodermatophilus are relatively more abundant in Meta-data. PM10 bacterial communities are similar to those of PM2.5 with some noticeable differences, i.e., at phylum level, more Firmicutes and less Actinobacteria present in PM10 samples than in PM2.5 samples, while at genus level, more Clostridium presents in PM10 samples. The findings in Beijing were compared with three 16S rRNA gene studies in other countries. Although the sampling locations and times are different from each other, compositions of bacterial community are similar for those sampled at the ground at