Terrestrial Subsurface Ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilkins, Michael J.; Fredrickson, Jim K.

2015-10-15

The Earth’s crust is a solid cool layer that overlays the mantle, with a varying thickness of between 30-50 km on continental plates, and 5-10 km on oceanic plates. Continental crust is composed of a variety of igneous, metamorphic, and sedimentary rocks that weather and re-form over geologic cycles lasting millions to billions of years. At the crust surface, these weathered minerals and organic material combine to produce a variety of soils types that provide suitable habitats and niches for abundant microbial diversity (see Chapter 4). Beneath this soil zone is the subsurface. Once thought to be relatively free ofmore » microorganisms, recent estimates have calculated that between 1016-1017 g C biomass (2-19% of Earth’s total biomass) may be present in this environment (Whitman et al., 1998;McMahon and Parnell, 2014). Microbial life in the subsurface exists across a wide range of habitats: in pores associated with relatively shallow unconsolidated aquifer sediments to fractures in bedrock formations that are more than a kilometer deep, where extreme lithostatic pressures and temperatures are encountered. While these different environments contain varying physical and chemical conditions, the absence of light is a constant. Despite this, diverse physiologies and metabolisms enable microorganisms to harness energy and carbon for growth in water-filled pore spaces and fractures. Carbon and other element cycles are driven by microbial activity, which has implications for both natural processes and human activities in the subsurface, e.g., bacteria play key roles in both hydrocarbon formation and degradation. Hydrocarbons are a major focus for human utilization of the subsurface, via oil and gas extraction and potential geologic CO2 sequestration. The subsurface is also utilized or being considered for sequestered storage of high-level radioactive waste from nuclear power generation and residual waste from past production of weapons grade nuclear materials. While our understanding of the subsurface is continually improving, it is clear that only a small fraction of microbial habitats have been sampled and studied. In this chapter, we will discuss these studies in the context of the distribution of microbial life in the subsurface, the stresses that microorganisms must overcome to survive in these environments, and the metabolic strategies that are employed to harness energy in a region of the planet far-removed from sunlight. Finally, we will consider both beneficial and deleterious effects of microbial activity in the subsurface on human activities in this environment.« less

Augmented In Situ Subsurface Bioremediation Process™BIO-REM, Inc. - Demonstration Bulletin

EPA Science Inventory

The Augmented In Situ Subsurface Bioremediation Process™ developed by BIO-REM, Inc., uses microaerophilic bacteria and micronutrients (H-10) and surface tension depressants/penetrants for the treatment of hydrocarbon contaminated soils and groundwater. The bacteria utilize hydroc...

Acoustic Characterization of Soil

DTIC Science & Technology

1996-03-28

modified SAR imaging algorithm. Page 26 Final Report In the acoustic subsurface imaging scenario, the "object" to be imaged (i.e., cultural artifacts... subsurface imaging scenario. To combat this potential difficulty we can utilize a new SAR imaging algorithm (Lee et al., 1996) derived from a geophysics...essentially a transmit plane wave. This is a cost-effective means to evaluate the feasibility of subsurface imaging . A more complete (and costly

Restricted access Improved hydrogeophysical characterization and monitoring through parallel modeling and inversion of time-domain resistivity andinduced-polarization data

USGS Publications Warehouse

Johnson, Timothy C.; Versteeg, Roelof J.; Ward, Andy; Day-Lewis, Frederick D.; Revil, André

2010-01-01

Electrical geophysical methods have found wide use in the growing discipline of hydrogeophysics for characterizing the electrical properties of the subsurface and for monitoring subsurface processes in terms of the spatiotemporal changes in subsurface conductivity, chargeability, and source currents they govern. Presently, multichannel and multielectrode data collections systems can collect large data sets in relatively short periods of time. Practitioners, however, often are unable to fully utilize these large data sets and the information they contain because of standard desktop-computer processing limitations. These limitations can be addressed by utilizing the storage and processing capabilities of parallel computing environments. We have developed a parallel distributed-memory forward and inverse modeling algorithm for analyzing resistivity and time-domain induced polar-ization (IP) data. The primary components of the parallel computations include distributed computation of the pole solutions in forward mode, distributed storage and computation of the Jacobian matrix in inverse mode, and parallel execution of the inverse equation solver. We have tested the corresponding parallel code in three efforts: (1) resistivity characterization of the Hanford 300 Area Integrated Field Research Challenge site in Hanford, Washington, U.S.A., (2) resistivity characterization of a volcanic island in the southern Tyrrhenian Sea in Italy, and (3) resistivity and IP monitoring of biostimulation at a Superfund site in Brandywine, Maryland, U.S.A. Inverse analysis of each of these data sets would be limited or impossible in a standard serial computing environment, which underscores the need for parallel high-performance computing to fully utilize the potential of electrical geophysical methods in hydrogeophysical applications.

Anatomy of Old Faithful From Subsurface Seismic Imaging of the Yellowstone Upper Geyser Basin

NASA Astrophysics Data System (ADS)

Wu, Sin-Mei; Ward, Kevin M.; Farrell, Jamie; Lin, Fan-Chi; Karplus, Marianne; Smith, Robert B.

2017-10-01

The Upper Geyser Basin in Yellowstone National Park contains one of the highest concentrations of hydrothermal features on Earth including the iconic Old Faithful geyser. Although this system has been the focus of many geological, geochemical, and geophysical studies for decades, the shallow (<200 m) subsurface structure remains poorly characterized. To investigate the detailed subsurface geologic structure including the hydrothermal plumbing of the Upper Geyser Basin, we deployed an array of densely spaced three-component nodal seismographs in November of 2015. In this study, we extract Rayleigh wave seismic signals between 1 and 10 Hz utilizing nondiffusive seismic waves excited by nearby active hydrothermal features with the following results: (1) imaging the shallow subsurface structure by utilizing stationary hydrothermal activity as a seismic source, (2) characterizing how local geologic conditions control the formation and location of the Old Faithful hydrothermal system, and (3) resolving a relatively shallow (10-60 m) and large reservoir located 100 m southwest of Old Faithful geyser.

Landfill disposal systems.

PubMed

Slimak, K M

1978-12-01

The current status of landfill disposal of hazardous wastes in the United States is indicated by presenting descriptions of six operating landfills. These landfills illustrate the variety of techniques that exist in landfill disposal of hazardous wastes. Although some landfills more effectively isolate hazardous waste than others, all landfills must deal with the following problems. Leachate from hazardous waste landfills is generally highly polluted. Most landfills attempt to contain leachate at the site and prevent its discharge to surface or groundwaters. To retain leachate within a disposal area, subsurface barriers of materials such as concrete, asphalt, butyl rubber, vinyl, and clay are used. It is difficult to assure that these materials can seal a landfill indefinitely. When a subsurface barrier fails, the leachate enters the groundwater in a concentrated, narrow band which may bypass monitoring wells. Once a subsurface barrier has failed, repairs are time-consuming and costly, since the waste above the repair site may have to be removed. The central problem in landfill disposal is leachate control. Recent emphasis has been on developing subsurface barriers to contain the wastes and any leachate. Future emphasis should also be on techniques for removing water from hazardous wastes before they are placed in landfills, and on methods for preventing contact of the wastes with water during and after disposal operations. When leachate is eliminated, the problems of monitoring, and subsurface barrier failure and repair can be addressed, and a waste can be effectively isolated.A surface seal landfill design is recommended for maintaining the dry state of solid hazardous wastes and for controlling leachate. Any impervious liner is utilized over the top of the landfill to prevent surface water from seeping into the waste. The surface barrier is also the site where monitoring and maintenance activities are focused. Barrier failure can be detected by visual inspections and any repairs can be made without disturbing the waste. The surface seal landfill does not employ a subsurface barrier. The surface seal landfill successfully addresses each of the four environmental problems listed above, provided that this landfill design is utilized for dry wastes only and is located at a site which provides protection from groundwater and temporary perched water tables.

Establishing sustainable strategies in urban underground engineering.

PubMed

Curiel-Esparza, Jorge; Canto-Perello, Julian; Calvo, Maria A

2004-07-01

Growth of urban areas, the corresponding increased demand for utility services and the possibility of new types of utility systems are overcrowding near surface underground space with urban utilities. Available subsurface space will continue to diminish to the point where utilidors (utility tunnels) may become inevitable. Establishing future sustainable strategies in urban underground engineering consists of the ability to lessen the use of traditional trenching. There is an increasing interest in utility tunnels for urban areas as a sustainable technique to avoid congestion of the subsurface. One of the principal advantages of utility tunnels is the substantially lower environmental impact compared with common trenches. Implementing these underground facilities is retarded most by the initial cost and management procedures. The habitual procedure is to meet problems as they arise in current practice. The moral imperative of sustainable strategies fails to confront the economic and political conflicts of interest. Municipal engineers should act as a key enabler in urban underground sustainable development.

Transducer Design Experiments for Ground-Penetrating Acoustic Systems

DTIC Science & Technology

1996-03-19

subsurface imaging experiments have utilized a source (Tx) and receiver (Rx) configuration in which signals produced by a transmitter at the soil surface...development in the field of acoustic subsurface imaging are as follows. First, a transmitter designed to minimize the emission of surface waves, while

3D Seismic Imaging over a Potential Collapse Structure

NASA Astrophysics Data System (ADS)

Gritto, Roland; O'Connell, Daniel; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

2016-04-01

The Middle-East has seen a recent boom in construction including the planning and development of complete new sub-sections of metropolitan areas. Before planning and construction can commence, however, the development areas need to be investigated to determine their suitability for the planned project. Subsurface parameters such as the type of material (soil/rock), thickness of top soil or rock layers, depth and elastic parameters of basement, for example, comprise important information needed before a decision concerning the suitability of the site for construction can be made. A similar problem arises in environmental impact studies, when subsurface parameters are needed to assess the geological heterogeneity of the subsurface. Environmental impact studies are typically required for each construction project, particularly for the scale of the aforementioned building boom in the Middle East. The current study was conducted in Qatar at the location of a future highway interchange to evaluate a suite of 3D seismic techniques in their effectiveness to interrogate the subsurface for the presence of karst-like collapse structures. The survey comprised an area of approximately 10,000 m2 and consisted of 550 source- and 192 receiver locations. The seismic source was an accelerated weight drop while the geophones consisted of 3-component 10 Hz velocity sensors. At present, we analyzed over 100,000 P-wave phase arrivals and performed high-resolution 3-D tomographic imaging of the shallow subsurface. Furthermore, dispersion analysis of recorded surface waves will be performed to obtain S-wave velocity profiles of the subsurface. Both results, in conjunction with density estimates, will be utilized to determine the elastic moduli of the subsurface rock layers.

Characterizing variable biogeochemical changes during the treatment of produced oilfield waste.

PubMed

Hildenbrand, Zacariah L; Santos, Inês C; Liden, Tiffany; Carlton, Doug D; Varona-Torres, Emmanuel; Martin, Misty S; Reyes, Michelle L; Mulla, Safwan R; Schug, Kevin A

2018-09-01

At the forefront of the discussions about climate change and energy independence has been the process of hydraulic fracturing, which utilizes large amounts of water, proppants, and chemical additives to stimulate sequestered hydrocarbons from impermeable subsurface strata. This process also produces large amounts of heterogeneous flowback and formation waters, the subsurface disposal of which has most recently been linked to the induction of anthropogenic earthquakes. As such, the management of these waste streams has provided a newfound impetus to explore recycling alternatives to reduce the reliance on subsurface disposal and fresh water resources. However, the biogeochemical characteristics of produced oilfield waste render its recycling and reutilization for production well stimulation a substantial challenge. Here we present a comprehensive analysis of produced waste from the Eagle Ford shale region before, during, and after treatment through adjustable separation, flocculation, and disinfection technologies. The collection of bulk measurements revealed significant reductions in suspended and dissolved constituents that could otherwise preclude untreated produced water from being utilized for production well stimulation. Additionally, a significant step-wise reduction in pertinent scaling and well-fouling elements was observed, in conjunction with notable fluctuations in the microbiomes of highly variable produced waters. Collectively, these data provide insight into the efficacies of available water treatment modalities within the shale energy sector, which is currently challenged with improving the environmental stewardship of produced water management. Copyright © 2018 Elsevier B.V. All rights reserved.

VERTICAL PROFILING OF VOCS IN GROUNDWATER AND SOIL VAPORS TO EVALUATE THE RISK OF VAPOR INTRUSION

EPA Science Inventory

The Draft EPA Subsurface Vapor Intrusion Guidance Document was established to address the incremental increases in exposures and risks from subsurface contaminants that may be intruding into indoor air@. The document utilizes attenuation factors based on indoor air/soil gas or i...

METHOD AND LOCATION OF GROUND WATER SAMPLING: IMPACT ON ATTENUATION FACTORS FOR ASSESSING IMPACT ON VAPOR INTRUSION

EPA Science Inventory

The Draft EPA Subsurface Vapor Intrusion Guidance Document was established to "address the incremental increases in exposures and risks from subsurface contaminants that my be intruding into indoor air". The document utilizes attenuation factors based on indoor air/soil gas or i...

Geologic setting and chemical characteristics of hot springs in central and western Alaska

USGS Publications Warehouse

Miller, Thomas P.; Barnes, Ivan; Pattan, William Wallace

1973-01-01

The geologic and chemical data are too preliminary to make an estimate of the potential of the hot springs as a geothermal resource. The data suggest, however, that most of the hot springs of central and western Alaska have relatively low subsurface temperatures and limited reservoir capacities in comparison with geothermal areas presently being utilized for electrical power generation.

Reverse-time migration for subsurface imaging using single- and multi- frequency components

NASA Astrophysics Data System (ADS)

Ha, J.; Kim, Y.; Kim, S.; Chung, W.; Shin, S.; Lee, D.

2017-12-01

Reverse-time migration is a seismic data processing method for obtaining accurate subsurface structure images from seismic data. This method has been applied to obtain more precise complex geological structure information, including steep dips, by considering wave propagation characteristics based on two-way traveltime. Recently, various studies have reported the characteristics of acquired datasets from different types of media. In particular, because real subsurface media is comprised of various types of structures, seismic data represent various responses. Among them, frequency characteristics can be used as an important indicator for analyzing wave propagation in subsurface structures. All frequency components are utilized in conventional reverse-time migration, but analyzing each component is required because they contain inherent seismic response characteristics. In this study, we propose a reverse-time migration method that utilizes single- and multi- frequency components for analyzing subsurface imaging. We performed a spectral decomposition to utilize the characteristics of non-stationary seismic data. We propose two types of imaging conditions, in which decomposed signals are applied in complex and envelope traces. The SEG/EAGE Overthrust model was used to demonstrate the proposed method, and the 1st derivative Gaussian function with a 10 Hz cutoff was used as the source signature. The results were more accurate and stable when relatively lower frequency components in the effective frequency range were used. By combining the gradient obtained from various frequency components, we confirmed that the results are clearer than the conventional method using all frequency components. Also, further study is required to effectively combine the multi-frequency components.

Remote sensing of subsurface water temperature by Raman scattering.

PubMed

Leonard, D A; Caputo, B; Hoge, F E

1979-06-01

The application of Raman scattering to remote sensing of subsurface water temperature and salinity is considered, and both theoretical and experimental aspects of the technique are discussed. Recent experimental field measurements obtained in coastal waters and on a trans-Atlantic/Mediterranean research cruise are correlated with theoretical expectations. It is concluded that the Raman technique for remote sensing of subsurface water temperature has been brought from theoretical and laboratory stages to the point where practical utilization can now be developed.

Monitoring an Induced Permafrost Warming Experiment Using ERT, Temperature, and NMR in Fairbanks, Alaska

NASA Astrophysics Data System (ADS)

Ulrich, C.; Ajo Franklin, J. B.; Ekblaw, I.; Lindsey, N.; Wagner, A. M.; Saari, S.; Daley, T. M.; Freifeld, B. M.

2016-12-01

As global temperatures continue to rise, permafrost landscapes will experience more rapid changes than other global climate zones. Permafrost thaw is a result of increased temperatures in arctic settings resulting in surface deformation and subsurface hydrology changes. From an engineering perspective, surface deformation poses a threat to the stability of existing infrastructure such as roads, utility piping, and building structures. Preemptively detecting or monitoring subsurface thaw dynamics presents a difficult challenge due to the long time scales as deformation occurs. Increased subsurface moisture content results from permafrost thaw of which electrical resistivity tomography (ERT), soil temperature, and nuclear magnetic resonance (NMR) are directly sensitive. In this experiment we evaluate spatial and temporal changes in subsurface permafrost conditions (moisture content and temperature) at a experimental heating plot in Fairbanks, AK. This study focuses on monitoring thaw signatures using multiple collocated electrical resistivity (ERT), borehole temperature, and borehole nuclear magnetic resonance (NMR) measurements. Timelapse ERT (sensitive to changes in moisture content) was inverted using collocated temperature and NMR to constrain ERT inversions. Subsurface thermal state was monitored with timelapse thermistors, sensitive to soil ice content. NMR was collected in multiple boreholes and is sensitive to changes in moisture content and pore scale distribution. As permafrost thaws more hydrogen, in the form of water, is available resulting in a changing NMR response. NMR requires the availability of liquid water in order to induce spin of the hydrogen molecule, hence, if frozen water molecules will be undetectable. In this study, the permafrost is poised close to 0oC and is mainly silt with small pore dimensions; this combination makes NMR particularly useful due to the possibility of sub-zero thaw conditions within the soil column. Overall this experiment presents a complementary suite of methods that provides feedback on subsurface permafrost state even in cases where soil texture might control unfrozen water content.

Electrical resistance tomography using steel cased boreholes as electrodes

DOEpatents

Daily, W.D.; Ramirez, A.L.

1999-06-22

An electrical resistance tomography method is described which uses steel cased boreholes as electrodes. The method enables mapping the electrical resistivity distribution in the subsurface from measurements of electrical potential caused by electrical currents injected into an array of electrodes in the subsurface. By use of current injection and potential measurement electrodes to generate data about the subsurface resistivity distribution, which data is then used in an inverse calculation, a model of the electrical resistivity distribution can be obtained. The inverse model may be constrained by independent data to better define an inverse solution. The method utilizes pairs of electrically conductive (steel) borehole casings as current injection electrodes and as potential measurement electrodes. The greater the number of steel cased boreholes in an array, the greater the amount of data is obtained. The steel cased boreholes may be utilized for either current injection or potential measurement electrodes. The subsurface model produced by this method can be 2 or 3 dimensional in resistivity depending on the detail desired in the calculated resistivity distribution and the amount of data to constrain the models. 2 figs.

Electrical resistance tomography using steel cased boreholes as electrodes

DOEpatents

Daily, William D.; Ramirez, Abelardo L.

1999-01-01

An electrical resistance tomography method using steel cased boreholes as electrodes. The method enables mapping the electrical resistivity distribution in the subsurface from measurements of electrical potential caused by electrical currents injected into an array of electrodes in the subsurface. By use of current injection and potential measurement electrodes to generate data about the subsurface resistivity distribution, which data is then used in an inverse calculation, a model of the electrical resistivity distribution can be obtained. The inverse model may be constrained by independent data to better define an inverse solution. The method utilizes pairs of electrically conductive (steel) borehole casings as current injection electrodes and as potential measurement electrodes. The greater the number of steel cased boreholes in an array, the greater the amount of data is obtained. The steel cased boreholes may be utilized for either current injection or potential measurement electrodes. The subsurface model produced by this method can be 2 or 3 dimensional in resistivity depending on the detail desired in the calculated resistivity distribution and the amount of data to constain the models.

Scenario simulation based assessment of subsurface energy storage

NASA Astrophysics Data System (ADS)

Beyer, C.; Bauer, S.; Dahmke, A.

2014-12-01

Energy production from renewable sources such as solar or wind power is characterized by temporally varying power supply. The politically intended transition towards renewable energies in Germany („Energiewende") hence requires the installation of energy storage technologies to compensate for the fluctuating production. In this context, subsurface energy storage represents a viable option due to large potential storage capacities and the wide prevalence of suited geological formations. Technologies for subsurface energy storage comprise cavern or deep porous media storage of synthetic hydrogen or methane from electrolysis and methanization, or compressed air, as well as heat storage in shallow or moderately deep porous formations. Pressure build-up, fluid displacement or temperature changes induced by such operations may affect local and regional groundwater flow, geomechanical behavior, groundwater geochemistry and microbiology. Moreover, subsurface energy storage may interact and possibly be in conflict with other "uses" like drinking water abstraction or ecological goods and functions. An utilization of the subsurface for energy storage therefore requires an adequate system and process understanding for the evaluation and assessment of possible impacts of specific storage operations on other types of subsurface use, the affected environment and protected entities. This contribution presents the framework of the ANGUS+ project, in which tools and methods are developed for these types of assessments. Synthetic but still realistic scenarios of geological energy storage are derived and parameterized for representative North German storage sites by data acquisition and evaluation, and experimental work. Coupled numerical hydraulic, thermal, mechanical and reactive transport (THMC) simulation tools are developed and applied to simulate the energy storage and subsurface usage scenarios, which are analyzed for an assessment and generalization of the imposed THMC-processes, mutual effects and influences on protected entities. The scenario analyses allow the deduction of monitoring concepts as well as a first methodology for large scale spatial planning of the geological subsurface. This concept is illustrated for different storage options and their impacts in space and time.

Development of a Carbon Sequestration Visualization Tool using Google Earth Pro

NASA Astrophysics Data System (ADS)

Keating, G. N.; Greene, M. K.

2008-12-01

The Big Sky Carbon Sequestration Partnership seeks to prepare organizations throughout the western United States for a possible carbon-constrained economy. Through the development of CO2 capture and subsurface sequestration technology, the Partnership is working to enable the region to cleanly utilize its abundant fossil energy resources. The intent of the Los Alamos National Laboratory Big Sky Visualization tool is to allow geochemists, geologists, geophysicists, project managers, and other project members to view, identify, and query the data collected from CO2 injection tests using a single data source platform, a mission to which Google Earth Pro is uniquely and ideally suited . The visualization framework enables fusion of data from disparate sources and allows investigators to fully explore spatial and temporal trends in CO2 fate and transport within a reservoir. 3-D subsurface wells are projected above ground in Google Earth as the KML anchor points for the presentation of various surface subsurface data. This solution is the most integrative and cost-effective possible for the variety of users in the Big Sky community.

Applicability of risk-based management and the need for risk-based economic decision analysis at hazardous waste contaminated sites.

PubMed

Khadam, Ibrahim; Kaluarachchi, Jagath J

2003-07-01

Decision analysis in subsurface contamination management is generally carried out through a traditional engineering economic viewpoint. However, new advances in human health risk assessment, namely, the probabilistic risk assessment, and the growing awareness of the importance of soft data in the decision-making process, require decision analysis methodologies that are capable of accommodating non-technical and politically biased qualitative information. In this work, we discuss the major limitations of the currently practiced decision analysis framework, which evolves around the definition of risk and cost of risk, and its poor ability to communicate risk-related information. A demonstration using a numerical example was conducted to provide insight on these limitations of the current decision analysis framework. The results from this simple ground water contamination and remediation scenario were identical to those obtained from studies carried out on existing Superfund sites, which suggests serious flaws in the current risk management framework. In order to provide a perspective on how these limitations may be avoided in future formulation of the management framework, more matured and well-accepted approaches to decision analysis in dam safety and the utility industry, where public health and public investment are of great concern, are presented and their applicability in subsurface remediation management is discussed. Finally, in light of the success of the application of risk-based decision analysis in dam safety and the utility industry, potential options for decision analysis in subsurface contamination management are discussed.

Strategies towards an optimized use of the shallow geothermal potential

NASA Astrophysics Data System (ADS)

Schelenz, S.; Firmbach, L.; Kalbacher, T.; Goerke, U.; Kolditz, O.; Dietrich, P.; Vienken, T.

2013-12-01

Thermal use of the shallow subsurface for heat generation, cooling and thermal energy storage is increasingly gaining importance in reconsideration of future energy supplies, e.g. in the course of German energy transition, with application shifting from isolated to intensive use. The planning and dimensioning of (geo-)thermal applications is strongly influenced by the availability of exploration data. Hence, reliable site-specific dimensioning of systems for the thermal use of the shallow subsurface will contribute to an increase in resource efficiency, cost reduction during installation and operation, as well as reduction of environmental impacts and prevention of resource over-exploitation. Despite large cumulative investments that are being made for the utilization of the shallow thermal potential, thermal energy is in many cases exploited without prior on-site exploration and investigation of the local geothermal potential, due to the lack of adequate and cost-efficient exploration techniques. We will present new strategies for an optimized utilization of urban thermal potential, showcased at a currently developed residential neighborhood with high demand for shallow geothermal applications, based on a) enhanced site characterization and b) simulation of different site specific application scenarios. For enhanced site characterization, surface geophysics and vertical high resolution direct push-profiling were combined for reliable determination of aquifer structure and aquifer parameterization. Based on the site characterization, different site specific geothermal application scenarios, including different system types and system configurations, were simulated using OpenGeoSys to guarantee an environmental and economic sustainable thermal use of the shallow subsurface.

Recalcitrant Carbonaceous Material: A Source of Electron Donors for Anaerobic Microbial Metabolisms in the Subsurface?

NASA Astrophysics Data System (ADS)

Nixon, S. L.; Montgomery, W.; Sephton, M. A.; Cockell, C. S.

2014-12-01

More than 90% of organic material on Earth resides in sedimentary rocks in the form of kerogens; fossilized organic matter formed through selective preservation of high molecular weight biopolymers under anoxic conditions. Despite its prevalence in the subsurface, the extent to which this material supports microbial metabolisms is unknown. Whilst aerobic microorganisms are known to derive energy from kerogens within shales, utilization in anaerobic microbial metabolisms that proliferate in the terrestrial subsurface, such as microbial iron reduction, has yet to be demonstrated. Data are presented from microbial growth experiments in which kerogens and shales were supplied as the sole electron donor source for microbial iron reduction by an enrichment culture. Four well-characterized kerogens samples (representative of Types I-IV, classified by starting material), and two shale samples, were assessed. Organic analysis was carried out to investigate major compound classes present in each starting material. Parallel experiments were conducted to test inhibition of microbial iron reduction in the presence of each material when the culture was supplied with a full redox couple. The results demonstrate that iron-reducing microorganisms in this culture were unable to use kerogens and shales as a source of electron donors for energy acquisition, despite the presence of compound classes known to support this metabolism. Furthermore, the presence of these materials was found to inhibit microbial iron reduction to varying degrees, with some samples leading to complete inhibition. These results suggest that recalcitrant carbonaceous material in the terrestrial subsurface is not available for microbial iron reduction and similar metabolisms, such as sulphate-reduction. Further research is needed to investigate the inhibition exerted by these materials, and to assess whether these findings apply to other microbial consortia. These results may have significant implications for the role of anaerobic microbial metabolisms in the subsurface terrestrial carbon cycle. Kerogens are chemically similar to organic material in carbonaceous chondrites. As such, further study may provide insight into the potential availability of organic compounds for microbial metabolisms operating in the subsurface of Mars.

Accurate modeling and inversion of electrical resistivity data in the presence of metallic infrastructure with known location and dimension

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Timothy C.; Wellman, Dawn M.

2015-06-26

Electrical resistivity tomography (ERT) has been widely used in environmental applications to study processes associated with subsurface contaminants and contaminant remediation. Anthropogenic alterations in subsurface electrical conductivity associated with contamination often originate from highly industrialized areas with significant amounts of buried metallic infrastructure. The deleterious influence of such infrastructure on imaging results generally limits the utility of ERT where it might otherwise prove useful for subsurface investigation and monitoring. In this manuscript we present a method of accurately modeling the effects of buried conductive infrastructure within the forward modeling algorithm, thereby removing them from the inversion results. The method ismore » implemented in parallel using immersed interface boundary conditions, whereby the global solution is reconstructed from a series of well-conditioned partial solutions. Forward modeling accuracy is demonstrated by comparison with analytic solutions. Synthetic imaging examples are used to investigate imaging capabilities within a subsurface containing electrically conductive buried tanks, transfer piping, and well casing, using both well casings and vertical electrode arrays as current sources and potential measurement electrodes. Results show that, although accurate infrastructure modeling removes the dominating influence of buried metallic features, the presence of metallic infrastructure degrades imaging resolution compared to standard ERT imaging. However, accurate imaging results may be obtained if electrodes are appropriately located.« less

A hybrid geothermal energy conversion technology: Auxiliary heating of geothermally preheated water or CO2 - a potential solution for low-temperature resources

NASA Astrophysics Data System (ADS)

Saar, Martin; Garapati, Nagasree; Adams, Benjamin; Randolph, Jimmy; Kuehn, Thomas

2016-04-01

Safe, sustainable, and economic development of deep geothermal resources, particularly in less favourable regions, often requires employment of unconventional geothermal energy extraction and utilization methods. Often "unconventional geothermal methods" is synonymously and solely used as meaning enhanced geothermal systems, where the permeability of hot, dry rock with naturally low permeability at greater depths (4-6 km), is enhanced. Here we present an alternative unconventional geothermal energy utilization approach that uses low-temperature regions that are shallower, thereby drastically reducing drilling costs. While not a pure geothermal energy system, this hybrid approach may enable utilization of geothermal energy in many regions worldwide that can otherwise not be used for geothermal electricity generation, thereby increasing the global geothermal resource base. Moreover, in some realizations of this hybrid approach that generate carbon dioxide (CO2), the technology may be combined with carbon dioxide capture and storage (CCS) and CO2-based geothermal energy utilization, resulting in a high-efficiency (hybrid) geothermal power plant with a negative carbon footprint. Typically, low- to moderate-temperature geothermal resources are more effectively used for direct heat energy applications. However, due to high thermal losses during transport, direct use requires that the heat resource is located near the user. Alternatively, we show here that if such a low-temperature geothermal resource is combined with an additional or secondary energy resource, the power production is increased compared to the sum from two separate (geothermal and secondary fuel) power plants (DiPippo et al. 1978) and the thermal losses are minimized because the thermal energy is utilized where it is produced. Since Adams et al. (2015) found that using CO2 as a subsurface working fluid produces more net power than brine at low- to moderate-temperature geothermal resource conditions, we compare over a range of parameters the net power and efficiencies of hybrid geothermal power plants that use brine or CO2 as the subsurface working fluid, that are then heated further with a secondary energy source that is unspecified here. Parameters varied include the subsurface working fluid (brine vs. CO2), geothermal reservoir depth (2.5-4.5 km), and turbine inlet temperature (200-600°C) after auxiliary heating. The hybrid power plant is numerically modeled using an iterative coupling approach of TOUGH2-ECO2N/ECO2H (Pruess, 2004) for simulation of the subsurface reservoir and Engineering Equation Solver for well bore fluid flow and surface power plant performance. We find that hybrid power plants that are CO2-based (subsurface) systems produce more net power than the sum of the power produced by individual power plants at low turbine inlet temperatures and brine based systems produce more power at high turbine inlet temperatures. Specifically, our results indicate that geothermal hybrid plants that are CO2-based are more efficient than brine-based systems when the contribution of the geothermal resource energy is higher than 48%.

A toolkit for determining historical eco-hydrological interactions

NASA Astrophysics Data System (ADS)

Singer, M. B.; Sargeant, C. I.; Evans, C. M.; Vallet-Coulomb, C.

2016-12-01

Contemporary climate change is predicted to result in perturbations to hydroclimatic regimes across the globe, with some regions forecast to become warmer and drier. Given that water is a primary determinant of vegetative health and productivity, we can expect shifts in the availability of this critical resource to have significant impacts on forested ecosystems. The subject is particularly complex in environments where multiple sources of water are potentially available to vegetation and which may also exhibit spatial and temporal variability. To anticipate how subsurface hydrological partitioning may evolve in the future and impact overlying vegetation, we require well constrained, historical data and a modelling framework for assessing the dynamics of subsurface hydrology. We outline a toolkit to retrospectively investigate dynamic water use by trees. We describe a synergistic approach, which combines isotope dendrochronology of tree ring cellulose with a biomechanical model, detailed climatic and isotopic data in endmember waters to assess the mean isotopic composition of source water used in annual tree rings. We identify the data requirements and suggest three versions of the toolkit based on data availability. We present sensitivity analyses in order to identify the key variables required to constrain model predictions and then develop empirical relationships for constraining these parameters based on climate records. We demonstrate our methodology within a Mediterranean riparian forest site and show how it can be used along with subsurface hydrological modelling to validate source water determinations, which are fundamental to understanding climatic fluctuations and trends in subsurface hydrology. We suggest that the utility of our toolkit is applicable in riparian zones and in a range of forest environments where distinct isotopic endmembers are present.

Competing Uses of Underground Systems Related to Energy Supply: Applying Single- and Multiphase Simulations for Site Characterization and Risk-Analysis

NASA Astrophysics Data System (ADS)

Kissinger, A.; Walter, L.; Darcis, M.; Flemisch, B.; Class, H.

2012-04-01

Global climate change, shortage of resources and the resulting turn towards renewable sources of energy lead to a growing demand for the utilization of subsurface systems. Among these competing uses are Carbon Capture and Storage (CCS), geothermal energy, nuclear waste disposal, "renewable" methane or hydrogen storage as well as the ongoing production of fossil resources like oil, gas, and coal. Besides competing among themselves, these technologies may also create conflicts with essential public interests like water supply. For example, the injection of CO2 into the underground causes an increase in pressure reaching far beyond the actual radius of influence of the CO2 plume, potentially leading to large amounts of displaced salt water. Finding suitable sites is a demanding task for several reasons. Natural systems as opposed to technical systems are always characterized by heterogeneity. Therefore, parameter uncertainty impedes reliable predictions towards capacity and safety of a site. State of the art numerical simulations combined with stochastic approaches need to be used to obtain a more reliable assessment of the involved risks and the radii of influence of the different processes. These simulations may include the modeling of single- and multiphase non-isothermal flow, geo-chemical and geo-mechanical processes in order to describe all relevant physical processes adequately. Stochastic approaches have the aim to estimate a bandwidth of the key output parameters based on uncertain input parameters. Risks for these different underground uses can then be made comparable with each other. Along with the importance and the urgency of the competing processes this may lead to a more profound basis for a decision. Communicating risks to stake holders and a concerned public is crucial for the success of finding a suitable site for CCS (or other subsurface utilization). We present and discuss first steps towards an approach for addressing the issue of competitive utilization of the subsurface and the required process of communication between scientists, engineers, policy makers, and societies.

Geo-material microfluidics at reservoir conditions for subsurface energy resource applications.

PubMed

Porter, Mark L; Jiménez-Martínez, Joaquín; Martinez, Ricardo; McCulloch, Quinn; Carey, J William; Viswanathan, Hari S

2015-10-21

Microfluidic investigations of flow and transport in porous and fractured media have the potential to play a significant role in the development of future subsurface energy resource technologies. However, the majority of experimental systems to date are limited in applicability due to operating conditions and/or the use of engineered material micromodels. We have developed a high pressure and temperature microfluidic experimental system that allows for direct observations of flow and transport within geo-material micromodels (e.g. rock, cement) at reservoir conditions. In this manuscript, we describe the experimental system, including our novel micromodel fabrication method that works in both geo- and engineered materials and utilizes 3-D tomography images of real fractures as micromodel templates to better represent the pore space and fracture geometries expected in subsurface formations. We present experimental results that highlight the advantages of using real-rock micromodels and discuss potential areas of research that could benefit from geo-material microfluidic investigations. The experiments include fracture-matrix interaction in which water imbibes into the shale rock matrix from etched fractures, supercritical CO2 (scCO2) displacing brine in idealized and realistic fracture patterns, and three-phase flow involving scCO2-brine-oil.

Australian Multiexperimental Assessment of SIR-B (AMAS)

NASA Technical Reports Server (NTRS)

Richards, J. A.; Forster, B. C.; Milne, A. K.; Taylor, G. R.; Trinder, J. C.

1984-01-01

The utility of SIR-B data for analysis of surface properties and subsurface morphology in three arid regions of Australia is investigated. This study area is located in western New South Wales. It contains extensive aeolian and alluvially derived depositional plains and is the site of the University's Arid Zone Research Station; it is well-mapped and surveyed. Radar backscatter is mapped and evaluated against known terrain conditions. Relative components of surface and subsurface return are determined with a view to identifying structural properties of surface and subsurface morphology. The capability of microwave remote sensing in locating likely groundwater sources in the Bancannia Basin, near Fowler's Gap is assessed.

Recovering Long-wavelength Velocity Models using Spectrogram Inversion with Single- and Multi-frequency Components

NASA Astrophysics Data System (ADS)

Ha, J.; Chung, W.; Shin, S.

2015-12-01

Many waveform inversion algorithms have been proposed in order to construct subsurface velocity structures from seismic data sets. These algorithms have suffered from computational burden, local minima problems, and the lack of low-frequency components. Computational efficiency can be improved by the application of back-propagation techniques and advances in computing hardware. In addition, waveform inversion algorithms, for obtaining long-wavelength velocity models, could avoid both the local minima problem and the effect of the lack of low-frequency components in seismic data. In this study, we proposed spectrogram inversion as a technique for recovering long-wavelength velocity models. In spectrogram inversion, decomposed frequency components from spectrograms of traces, in the observed and calculated data, are utilized to generate traces with reproduced low-frequency components. Moreover, since each decomposed component can reveal the different characteristics of a subsurface structure, several frequency components were utilized to analyze the velocity features in the subsurface. We performed the spectrogram inversion using a modified SEG/SEGE salt A-A' line. Numerical results demonstrate that spectrogram inversion could also recover the long-wavelength velocity features. However, inversion results varied according to the frequency components utilized. Based on the results of inversion using a decomposed single-frequency component, we noticed that robust inversion results are obtained when a dominant frequency component of the spectrogram was utilized. In addition, detailed information on recovered long-wavelength velocity models was obtained using a multi-frequency component combined with single-frequency components. Numerical examples indicate that various detailed analyses of long-wavelength velocity models can be carried out utilizing several frequency components.

Field Tests of the Magnetotelluric Method to Detect Gas Hydrates, Mallik, Mackenzie Delta, Canada

NASA Astrophysics Data System (ADS)

Craven, J. A.; Roberts, B.; Bellefleur, G.; Spratt, J.; Wright, F.; Dallimore, S. R.

2008-12-01

The magnetotelluric method is not generally utilized at extreme latitudes due primarily to difficulties in making the good electrical contact with the ground required to measure the electric field. As such, the magnetotelluric technique has not been previously investigated to direct detect gas hydrates in on-shore permafrost environments. We present the results of preliminary field tests at Mallik, Northwest Territories, Canada, that demonstrate good quality magnetotelluric data can be obtained in this environment using specialized electrodes and buffer amplifiers similar to those utilized by Wannamaker et al (2004). This result suggests that subsurface images from larger magnetotelluric surveys will be useful to complement other techniques to detect, quantify and characterize gas hydrates.

Cost and time benefits for using subsurface utility engineering in Louisiana : research project capsule.

DOT National Transportation Integrated Search

2016-04-01

The objectives of this research are: to establish a record of all major projects : where DOTD has used SUE services in the past (SUE quality levels depicted : in Figure 1), including : interviews with various : DOTD personnel, : utility companies, an...

Isolation and Metabolic Characteristics of Previously Uncultured Members of the Order Aquificales in a Subsurface Gold Mine

PubMed Central

Takai, Ken; Hirayama, Hisako; Sakihama, Yuri; Inagaki, Fumio; Yamato, Yu; Horikoshi, Koki

2002-01-01

Culture-dependent and -independent techniques were combined to characterize the physiological properties and the ecological impacts of culture-resistant phylotypes of thermophiles within the order Aquificales from a subsurface hot aquifer of a Japanese gold mine. Thermophilic bacteria phylogenetically associated with previously uncultured phylotypes of Aquificales were successfully isolated. 16S ribosomal DNA clone analysis of the entire microbial DNA assemblage and fluorescence in situ whole-cell hybridization analysis indicated that the isolates dominated the microbial population in the subsurface aquifer. The isolates were facultatively anaerobic, hydrogen- or sulfur/thiosulfate-oxidizing, thermophilic chemolithoautotrophs utilizing molecular oxygen, nitrate, ferric iron, arsenate, selenate, and selenite as electron acceptors. Their versatile energy-generating systems may reflect the geochemical conditions of their habitat in the geothermally active subsurface gold mine. PMID:12039766

Geothermal studies at Kirtland Air Force Base, Albuquerque, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riddle, L.; Grant, B.

Due to an effort by government installations to discontinue use of natural gas, alternative energy sources are being investigated at Kirtland Air Force Base, Albuquerque, New Mexico. New Mexico has geologic characteristics favorable for geothermal energy utilization. Local heat flow and geochemical studies indicate a normal subsurface temperature regime. The alluvial deposits, however, extend to great depths where hot fluids, heated by the normal geothermal gradient, could be encountered. Two potential models for tapping geothermal energy are presented: the basin model and the fault model.

Utilizing the permafrost on Mars

NASA Technical Reports Server (NTRS)

Phillips, L.

1985-01-01

It is noted that analogy between earth landforms resulting from the presence of permafrost has led to the suggestion that ground ice or water was at one time present on Mars. Only a regolith sample will confirm this. With these technologies as background, and known locations of subsurface water, development of a water supply base on Mars can then assume validity and significance. Current practices in terrestrial periglacial environments may be applicable to the Martian situation, taking into account site specific modifications of these techniques.

Active fungi amidst a marine subsurface RNA paleome

NASA Astrophysics Data System (ADS)

Orsi, W.; Biddle, J.; Edgcomb, V.

2012-12-01

The deep marine subsurface is a vast habitat for microbial life where cells may live on geologic timescales. Since extracellular DNA in sediments may be preserved on long timescales, ribosomal RNA (rRNA) is suggested to be a proxy for the active fraction of a microbial community in the subsurface. During an investigation of eukaryotic 18S rRNA signatures by amplicon pyrosequencing, metazoan, plant, and diatom rRNA signatures were recovered from marine sediments up to 2.7 million years old, suggesting that rRNA may be much more stable than previously considered in the marine subsurface. This finding confirms the concept of a paleome, extending it to include rRNA. Within the same dataset, unique profiles of fungi were found across a range of marine subsurface provinces exhibiting statistically significant correlations with total organic carbon (TOC), sulfide, and dissolved inorganic carbon (DIC). Sequences from metazoans, plants and diatoms showed different correlation patterns, consistent with a depth-controlled paleome. The fungal correlations with geochemistry allow the inference that some fungi are active and adapted for survival in the marine subsurface. A metatranscriptomic analysis of fungal derived mRNA confirms that fungi are metabolically active and utilize a range of organic and inorganic substrates in the marine subsurface.

Exploitation of Microdoppler and Multiple Scattering Phenomena for Radar Target Recognition

DTIC Science & Technology

2006-08-24

is tested with measurement data. The resulting GPR images demonstrate the effectiveness of the proposed algorithm. INTRODUCTION Subsurface imaging to...utilizes the fast Fourier . transform (FFT) to expedite the imaging GPR. Recently, we re- .... ported a fast and effective SAR-based subsurface ... imaging tech- nique that can provide good resolutions in both the range and cross-range domains I111. Our algorithm differs from Witten’s [91 and Hansen’s

Viscoelasticity of multiphase fluids: future directions

NASA Astrophysics Data System (ADS)

Tisato, Nicola; Spikes, Kyle; Javadpour, Farzam

2016-04-01

Recently, it has been demonstrated that rocks saturated with bubbly fluids attenuate seismic waves as the propagating elastic wave causes a thermodynamic disequilibrium between the liquid and the gas phases. The new attenuation mechanism, which is called wave-induced-gas-exsolution-dissolution (WIGED) and previously, was only postulated, opens up new perspectives for exploration geophysics as it could potentially improve the imaging of the subsurface. In particular, accounting for WIGED during seismic inversion could allow to better decipher seismic waves to disclose information about saturating phases. This will improve, for instance, the mapping of subsurface gas-plumes that might form during anthropogenic activities or natural phenomena such as those prior to volcanic eruptions. In the present contribution we will report the theory and the numerical method utilized to calculate the seismic-wave-attenuation related to WIGED and we will underline the assumptions and the limitations related to the theory. Then, we will present the experimental and the numerical strategy that we will employ to improve WIGED theory in order to incorporate additional effects, such as the role of interfacial tensions, or to extend it to fluid-fluid interaction

Innovating Big Data Computing Geoprocessing for Analysis of Engineered-Natural Systems

NASA Astrophysics Data System (ADS)

Rose, K.; Baker, V.; Bauer, J. R.; Vasylkivska, V.

2016-12-01

Big data computing and analytical techniques offer opportunities to improve predictions about subsurface systems while quantifying and characterizing associated uncertainties from these analyses. Spatial analysis, big data and otherwise, of subsurface natural and engineered systems are based on variable resolution, discontinuous, and often point-driven data to represent continuous phenomena. We will present examples from two spatio-temporal methods that have been adapted for use with big datasets and big data geo-processing capabilities. The first approach uses regional earthquake data to evaluate spatio-temporal trends associated with natural and induced seismicity. The second algorithm, the Variable Grid Method (VGM), is a flexible approach that presents spatial trends and patterns, such as those resulting from interpolation methods, while simultaneously visualizing and quantifying uncertainty in the underlying spatial datasets. In this presentation we will show how we are utilizing Hadoop to store and perform spatial analyses to efficiently consume and utilize large geospatial data in these custom analytical algorithms through the development of custom Spark and MapReduce applications that incorporate ESRI Hadoop libraries. The team will present custom `Big Data' geospatial applications that run on the Hadoop cluster and integrate with ESRI ArcMap with the team's probabilistic VGM approach. The VGM-Hadoop tool has been specially built as a multi-step MapReduce application running on the Hadoop cluster for the purpose of data reduction. This reduction is accomplished by generating multi-resolution, non-overlapping, attributed topology that is then further processed using ESRI's geostatistical analyst to convey a probabilistic model of a chosen study region. Finally, we will share our approach for implementation of data reduction and topology generation via custom multi-step Hadoop applications, performance benchmarking comparisons, and Hadoop-centric opportunities for greater parallelization of geospatial operations.

Characterization of Subsurface Defects in Ceramic Rods by Laser Scattering and Fractography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, J. M.; Sun, J. G.; Andrews, M. J.

2006-03-06

Silicon nitride ceramics are leading materials being evaluated for valve train components in diesel engine applications. The surface and subsurface defects and damage induced by surface machining can significantly affect component strength and lifetime. In this study, a nondestructive evaluation (NDE) technique based upon laser scattering has been utilized to analyze eight transversely ground silicon nitride cylindrical rods before fracture tests. The fracture origins (machining cracks or material-inherent flaws) identified by fractography after fracture testing were correlated with laser scattering images. The results indicate that laser scattering is able to identify possible fracture origin in the silicon nitride subsurface withoutmore » the need for destructive fracture tests.« less

Modeling the spatio-temporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape: Modeling Archive

DOE Data Explorer

Kumar, Jitendra; Collier, Nathan; Bisht, Gautam; Mills, Richard T.; Thornton, Peter E.; Iversen, Colleen M.; Romanovsky, Vladimir

2016-01-27

This Modeling Archive is in support of an NGEE Arctic discussion paper under review and available at http://www.the-cryosphere-discuss.net/tc-2016-29/. Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to atmosphere under warming climate. Ice--wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. The microtopography plays a critical role in regulating the fine scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behaviour under current as well as changing climate. We present here an end-to-end effort for high resolution numerical modeling of thermal hydrology at real-world field sites, utilizing the best available data to characterize and parameterize the models. We develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites at Barrow, Alaska spanning across low to transitional to high-centered polygon and representative of broad polygonal tundra landscape. A multi--phase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using high resolution LiDAR DEM, microtopographic features of the landscape were characterized and represented in the high resolution model mesh. Best available soil data from field observations and literature was utilized to represent the complex hetogeneous subsurface in the numerical model. This data collection provides the complete set of input files, forcing data sets and computational meshes for simulations using PFLOTRAN for four sites at Barrow Environmental Observatory. It also document the complete computational workflow for this modeling study to allow verification, reproducibility and follow up studies.

Computational Evaluation of Mg–Salen Compounds as Subsurface Fluid Tracers: Molecular Dynamics Simulations in Toluene–Water Mixtures and Clay Mineral Nanopores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greathouse, Jeffery A.; Boyle, Timothy J.; Kemp, Richard A.

Molecular tracers that can be selectively placed underground and uniquely identified at the surface using simple on-site spectroscopic methods would significantly enhance subsurface fluid monitoring capabilities. To ensure their widespread utility, the solubility of these tracers must be easily tuned to oil- or water-wet conditions as well as reducing or eliminating their propensity to adsorb onto subsurface rock and/or mineral phases. In this work, molecular dynamics simulations were used to investigate the relative solubilities and mineral surface adsorption properties of three candidate tracer compounds comprising Mg–salen derivatives of varying degrees of hydrophilic character. Simulations in water–toluene liquid mixtures indicate thatmore » the partitioning of each Mg–salen compound relative to the interface is strongly influenced by the degree of hydrophobicity of the compound. Simulations of these complexes in fluid-filled mineral nanopores containing neutral (kaolinite) and negatively charged (montmorillonite) mineral surfaces reveal that adsorption tendencies depend upon a variety of parameters, including tracer chemical properties, mineral surface type, and solvent type (water or toluene). Simulation snapshots and averaged density profiles reveal insight into the solvation and adsorption mechanisms that control the partitioning of these complexes in mixed liquid phases and nanopore environments. As a result, this work demonstrates the utility of molecular simulation in the design and screening of molecular tracers for use in subsurface applications.« less

Computational Evaluation of Mg–Salen Compounds as Subsurface Fluid Tracers: Molecular Dynamics Simulations in Toluene–Water Mixtures and Clay Mineral Nanopores

DOE PAGES

Greathouse, Jeffery A.; Boyle, Timothy J.; Kemp, Richard A.

2018-04-11

Molecular tracers that can be selectively placed underground and uniquely identified at the surface using simple on-site spectroscopic methods would significantly enhance subsurface fluid monitoring capabilities. To ensure their widespread utility, the solubility of these tracers must be easily tuned to oil- or water-wet conditions as well as reducing or eliminating their propensity to adsorb onto subsurface rock and/or mineral phases. In this work, molecular dynamics simulations were used to investigate the relative solubilities and mineral surface adsorption properties of three candidate tracer compounds comprising Mg–salen derivatives of varying degrees of hydrophilic character. Simulations in water–toluene liquid mixtures indicate thatmore » the partitioning of each Mg–salen compound relative to the interface is strongly influenced by the degree of hydrophobicity of the compound. Simulations of these complexes in fluid-filled mineral nanopores containing neutral (kaolinite) and negatively charged (montmorillonite) mineral surfaces reveal that adsorption tendencies depend upon a variety of parameters, including tracer chemical properties, mineral surface type, and solvent type (water or toluene). Simulation snapshots and averaged density profiles reveal insight into the solvation and adsorption mechanisms that control the partitioning of these complexes in mixed liquid phases and nanopore environments. As a result, this work demonstrates the utility of molecular simulation in the design and screening of molecular tracers for use in subsurface applications.« less

GeoEn -Research on Geo-Energy

NASA Astrophysics Data System (ADS)

Liebscher, A.; Scheck-Wenderoth, M.; GeoEn Research Group

2012-04-01

Axel Liebscher1, Magdalena Scheck-Wenderoth1 and the GeoEn Research Group1, 2,3 1 Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany 2 University Potsdam, Germany 3 BTU Cottbus, Germany One of the pressing challenges for the 21st century is a secure, sustainable and economical energy supply at simultaneous mitigation of its climate impact. Besides a switch to renewable energy resources, the exploration and exploitation of new, unconventional energy resources will play a major role as will the further use of fossil fuels. With the switch to renewable energies the question of geological energy storage will become an important topic whereas further use of fossil fuels requires strategies like CCS to reduce its negative climate impacts. These different aspects of geo-energy make complementary or competitive demands on the subsurface and its use. It is therefore essential to treat the subsurface as a geo-resource of its own right. So far, geo-resource related research has often focused on specific resource systems, e.g. ore forming systems, hydrocarbon systems or geothermal systems, providing results largely applicable only to the restricted range of physicochemical properties of the respective geo-resource systems. However, with the increasing use of the subsurface as important geo-resource, the different geo-resource systems tend to overlap and interact and also become much more complex due to the additional use or presence of artificial and technical matter, as is the case in geological CO2 storage. On the other hand, the combined use of the subsurface for different purposes may also create synergetic effects. GeoEn is a joint research project explicitly addressing the fundamental questions related to the sustainable and holistic use of the geo-resource subsurface with a special focus on geo-energy. Project partners are the German Research Centre for Geosciences (GFZ), the University of Potsdam (UP) and the Brandenburg University of Technology (BTU). GeoEn research addresses CO2 capture, transport and utilization, CO2 storage, the unconventional energy resource shale gas and geothermal technologies. These four core topics are studied in an integrated approach using the synergy of cross-cutting themes. The latter encompass new exploration and reservoir technologies as well as innovative monitoring methods, both complemented by numerical simulations of the relevant processes including flow dynamics or heat transfer in the subsurface and along the technological process chains. Accordingly, synergies derived from the cross-cutting topics improve both methodological development applicable in equal measure to the utilization of geothermal energy and of shale gas as well as to the use and monitoring of CO2 storage. Complementary, new modelling approaches are developed that allow the simulation of involved processes to predict the occurrence and physical properties of potential reservoirs and the changes that may be induced by their utilization. We present first results with respect to exploration strategies, monitoring technologies and modeling approaches for the pilot storage site for CO2 in Ketzin and the geothermal research platform Groß-Schönebeck, where the respective technologies are tested and monitored.

Data on subsurface storage of liquid waste near Pensacola, Florida, 1963-1980

USGS Publications Warehouse

Hull, R.W.; Martin, J.B.

1982-01-01

Since 1963, when industrial waste was first injected into the subsurface in northwest Florida, considerable data have been collected relating to the geochemistry of subsurface waste storage. This report presents hydrogeologic data on two subsurface waste storage. This report presents hydrogeologic data on two subsurface storage systems near Pensacola, Fla., which inject liquid industrial waste through deep wells into a saline aquifer. Injection sites are described giving a history of well construction, injection, and testing; geologic data from cores and grab samples; hydrographs of injection rates, volume, pressure, and water levels; and chemical and physical data from water-quality samples collected from injection and monitor wells. (USGS)

Parametric study on the behavior of an innovative subsurface tension leg platform in ultra-deep water

NASA Astrophysics Data System (ADS)

Zhen, Xing-wei; Huang, Yi

2017-10-01

This study focuses on a new technology of Subsurface Tension Leg Platform (STLP), which utilizes the shallowwater rated well completion equipment and technology for the development of large oil and gas fields in ultra-deep water (UDW). Thus, the STLP concept offers attractive advantages over conventional field development concepts. STLP is basically a pre-installed Subsurface Sea-star Platform (SSP), which supports rigid risers and shallow-water rated well completion equipment. The paper details the results of the parametric study on the behavior of STLP at a water depth of 3000 m. At first, a general description of the STLP configuration and working principle is introduced. Then, the numerical models for the global analysis of the STLP in waves and current are presented. After that, extensive parametric studies are carried out with regarding to SSP/tethers system analysis, global dynamic analysis and riser interference analysis. Critical points are addressed on the mooring pattern and riser arrangement under the influence of ocean current, to ensure that the requirements on SSP stability and riser interference are well satisfied. Finally, conclusions and discussions are made. The results indicate that STLP is a competitive well and riser solution in up to 3000 m water depth for offshore petroleum production.

Adaptive management for subsurface pressure and plume control in application to geological CO2 storage

NASA Astrophysics Data System (ADS)

Gonzalez-Nicolas, A.; Cihan, A.; Birkholzer, J. T.; Petrusak, R.; Zhou, Q.; Riestenberg, D. E.; Trautz, R. C.; Godec, M.

2016-12-01

Industrial-scale injection of CO2 into the subsurface can cause reservoir pressure increases that must be properly controlled to prevent any potential environmental impact. Excessive pressure buildup in reservoir may result in ground water contamination stemming from leakage through conductive pathways, such as improperly plugged abandoned wells or distant faults, and the potential for fault reactivation and possibly seal breaching. Brine extraction is a viable approach for managing formation pressure, effective stress, and plume movement during industrial-scale CO2 injection projects. The main objectives of this study are to investigate suitable different pressure management strategies involving active brine extraction and passive pressure relief wells. Adaptive optimized management of CO2 storage projects utilizes the advanced automated optimization algorithms and suitable process models. The adaptive management integrates monitoring, forward modeling, inversion modeling and optimization through an iterative process. In this study, we employ an adaptive framework to understand primarily the effects of initial site characterization and frequency of the model update (calibration) and optimization calculations for controlling extraction rates based on the monitoring data on the accuracy and the success of the management without violating pressure buildup constraints in the subsurface reservoir system. We will present results of applying the adaptive framework to test appropriateness of different management strategies for a realistic field injection project.

Geo-material microfluidics at reservoir conditions for subsurface energy resource applications

DOE PAGES

Porter, Mark L.; Jiménez-Martínez, Joaquín; Martinez, Ricardo Martin; ...

2015-08-20

Microfluidic investigations of flow and transport in porous and fractured media have the potential to play a significant role in the development of future subsurface energy resource technologies. However, the majority of experimental systems to date are limited in applicability due to operating conditions and/or the use of engineered material micromodels. In this paper, we have developed a high pressure and temperature microfluidic experimental system that allows for direct observations of flow and transport within geo-material micromodels (e.g. rock, cement) at reservoir conditions. In this manuscript, we describe the experimental system, including our novel micromodel fabrication method that works inmore » both geo- and engineered materials and utilizes 3-D tomography images of real fractures as micromodel templates to better represent the pore space and fracture geometries expected in subsurface formations. We present experimental results that highlight the advantages of using real-rock micromodels and discuss potential areas of research that could benefit from geo-material microfluidic investigations. Finally, the experiments include fracture–matrix interaction in which water imbibes into the shale rock matrix from etched fractures, supercritical CO 2 (scCO 2) displacing brine in idealized and realistic fracture patterns, and three-phase flow involving scCO 2–brine–oil.« less

Human utilization of subsurface extraterrestrial environments.

PubMed

Boston, P J; Frederick, R D; Welch, S M; Werker, J; Meyer, T R; Sprungman, B; Hildreth-Werker, V; Thompson, S L; Murphy, D L

2003-06-01

Caves have been used in the ancient past as shelter or habitat by many organisms (including humans). Since antiquity, humans have explored caves for the minerals they contain and sometimes for ceremonial purposes. Over the past century, caves have become the target of increasing exploration, scientific research, and recreation. The use of caves on extraterrestrial bodies for human habitation has been suggested by several investigators. Lunar lava tube bases received early attention because lava tubes were clearly visible in lunar images from the Apollo Era. More recently, Mars Observer Camera data has shown us clear evidence of large tubes visible in a number of volcanic regions on Mars. The budding field of cave geomicrobiology has direct application to questions about subsurface life on other planets. Caves contain many unusual organisms making their living from unlikely materials like manganese, iron, and sulfur. This makes caves and other subsurface habitats prime targets for astrobiological missions to Mars and possibly other bodies. We present the results of a completed Phase I and on-going Phase II NASA Institute for Advanced Concepts (NIAC) study that intensively examines the possibilities of using extraterrestrial caves as both a resource for human explorers and as a highly promising scientific target for both robotic and future human missions to Mars and beyond.

Biofilm formation and potential for iron cycling in serpentinization-influenced groundwater of the Zambales and Coast Range ophiolites.

PubMed

Meyer-Dombard, D'Arcy R; Casar, Caitlin P; Simon, Alexander G; Cardace, Dawn; Schrenk, Matthew O; Arcilla, Carlo A

2018-05-01

Terrestrial serpentinizing systems harbor microbial subsurface life. Passive or active microbially mediated iron transformations at alkaline conditions in deep biosphere serpentinizing ecosystems are understudied. We explore these processes in the Zambales (Philippines) and Coast Range (CA, USA) ophiolites, and associated surface ecosystems by probing the relevance of samples acquired at the surface to in situ, subsurface ecosystems, and the nature of microbe-mineral associations in the subsurface. In this pilot study, we use microcosm experiments and batch culturing directed at iron redox transformations to confirm thermodynamically based predictions that iron transformations may be important in subsurface serpentinizing ecosystems. Biofilms formed on rock cores from the Zambales ophiolite on surface and in-pit associations, confirming that organisms from serpentinizing systems can form biofilms in subsurface environments. Analysis by XPS and FTIR confirmed that enrichment culturing utilizing ferric iron growth substrates produced reduced, magnetic solids containing siderite, spinels, and FeO minerals. Microcosms and enrichment cultures supported organisms whose near relatives participate in iron redox transformations. Further, a potential 'principal' microbial community common to solid samples in serpentinizing systems was identified. These results indicate collectively that iron redox transformations should be more thoroughly and universally considered when assessing the function of terrestrial subsurface ecosystems driven by serpentinization.

Leachate plume delineation and lithologic profiling using surface resistivity in an open municipal solid waste dumpsite, Sri Lanka.

PubMed

Wijesekara, Hasintha Rangana; De Silva, Sunethra Nalin; Wijesundara, Dharani Thanuja De Silva; Basnayake, Bendict Francis Antony; Vithanage, Meththika Suharshini

2015-01-01

This study presents the use of direct current resistivity techniques (DCRT) for investigation and characterization of leachate-contaminated subsurface environment of an open solid waste dumpsite at Kandy, Sri Lanka. The particular dumpsite has no liner and hence the leachate flows directly to the nearby river via subsurface and surface channels. For the identification of possible subsurface flow paths and the direction of the leachate, DCRT (two-dimensional, three-dimensional and vertical electrical sounding) have been applied. In addition, the physico-chemical parameters such as pH, electrical conductivity (EC), alkalinity, hardness, chloride, chemical oxygen demand (COD) and total organic carbon (TOC) of leachate collected from different points of the solid waste dumping area and leachate drainage channel were analysed. Resistivity data confirmed that the leachate flow is confined to the near surface and no separate plume is observed in the downstream area, which may be due to the contamination distribution in the shallow overburden thickness. The stratigraphy with leachate pockets and leachate plume movements was well demarcated inside the dumpsite via low resistivity zones (1-3 Ωm). The recorded EC, alkalinity, hardness and chloride contents in leachate were averaged as 14.13 mS cm⁻¹, 3236, 2241 and 320 mg L⁻¹, respectively, which confirmed the possible causes for low resistivity values. This study confirms that DCRT can be effectively utilized to assess the subsurface characteristics of the open dumpsites to decide on corridor placement and depth of permeable reactive barriers to reduce the groundwater contamination.

Fungal Survival in a Chemosynthetic Ecosystem

NASA Astrophysics Data System (ADS)

Kiel Reese, B.; Sobol, M. S.; Hoshino, T.; Inagaki, F.; Eder, E.; Nicora, C. D.; Heyman, H. M.; Kyle, J. E.; Hoyt, D. W.; Tfaily, M. M.; Metz, T. O.

2018-05-01

Fungi possess metabolic pathways capable of utilizing previously considered non-bioavailable energy reserves. Metabolically active fungi occupy a unique niche within the subsurface, providing an organic carbon source for heterotrophic prokaryotes.

Detecting a subsurface cylinder by a Time Reversal MUSIC like method

NASA Astrophysics Data System (ADS)

Solimene, Raffaele; Dell'Aversano, Angela; Leone, Giovanni

2014-05-01

In this contribution the problem of imaging a buried homogeneous circular cylinder is dealt with for a two-dimensional scalar geometry. Though the addressed geometry is extremely simple as compared to real world scenarios, it can be considered of interest for a classical GPR civil engineering applicative context: that is the subsurface prospecting of urban area in order to detect and locate buried utilities. A large body of methods for subsurface imaging have been presented in literature [1], ranging from migration algorithms to non-linear inverse scattering approaches. More recently, also spectral estimation methods, which benefit from sub-array data arrangement, have been proposed and compared in [2].Here a Time Reversal MUSIC (TRM) like method is employed. TRM has been initially conceived to detect point-like scatterers and then generalized to the case of extended scatterers [3]. In the latter case, no a priori information about the scatterers is exploited. However, utilities often can be schematized as circular cylinders. Here, we develop a TRM variant which use this information to properly tailor the steering vector while implementing TRM. Accordingly, instead of a spatial map [3], the imaging procedure returns the scatterer's parameters such as its center position, radius and dielectric permittivity. The study is developed by numerical simulations. First the free-space case is considered in order to more easily introduce the idea and the problem mathematical structure. Then the analysis is extended to the half-space case. In both situations a FDTD forward solver is used to generate the synthetic data. As usual in TRM, a multi-view/multi-static single-frequency configuration is considered and emphasis is put on the role played by the number of available sensors. Acknowledgement This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar." [1] A. Randazzo and R. Solimene, 'Development Of New Methods For The Solution Of Inverse Electromagnetic Scattering Problems By Buried Structures: State of the Art and Open Issues ,'in COST ACTION TU1208: CIVIL ENGINEERING APPLICATIONS OF GROUND PENETRATING RADAR, Proceedings of first Action's General Meeting, 2013. ISBN: 978-88-548-6191-6. [2] S. Meschino, L. Pajewski, M. Pastorino, A. Randazzo, G. Schettini, "Detection of subsurface metallic utilities by means of a SAP technique: Comparing MUSIC- and SVM-based approaches, Journal of Applied Geophysics, vol. 97, pp. 60-68, 2013. [3] E. A. Marengo, F. K. Gruber, F. Simonetti, 'Time-reversal MUSIC imaging of extended targets,' IEEE Trans Image Process. vol. 16, pp. 1967-84, 2007

Mars penetrator: Subsurface science mission

NASA Technical Reports Server (NTRS)

Lumpkin, C. K.

1974-01-01

A penetrator system to emplace subsurface science on the planet Mars is described. The need for subsurface science is discussed, and the technologies for achieving successful atmospheric entry, Mars penetration, and data retrieval are presented.

Habitat Inspection Scanner, Bio-Structure Scanner, and In Situ Sub-Surface Composition Sensor

NASA Technical Reports Server (NTRS)

VanSteenberg, Michael

2004-01-01

The extension of dielectric and inductive spectroscopy into in situ observations represents a significant exploration-enabling tool. This technology can be widely applied from microscopic to macroscopic. Dielectrometry and inductometry can measure sub-surface composition and its distribution. The primary environment that we cannot easily explored is the sub-surface of solid bodies. Weather as part of our equipment that we bring with us, or the locations we are exploring. These fundamental questions lie at the core of the exploration Initiative. To answer them we must use a whole host of complimentary tools including those that allow us to practically examine the sub-surface environment. A nondestructive approach offers significant advantages for both the initial identification of likely samples but also the monitoring of ecosystems and crew health. These include materials characterization, nondestructive inspection, and process quality control, damage monitoring, and hidden object detection and identification. The identification of natural resources such as water on the Moon or Mars is of great importance to the utilization of local resource in the support of human exploration crews. On the macroscopic scale, the understanding of what resources are available and how they are distributed is of primary importance to their productive utilization. Even if initial explorations do not require the use of local resources to succeed, eventual settlement and commercial development will. The routine examination of the structural integrity (micro cracks, leaks) of hi.inafi habitats in harsh envkmments ww!d also be enabled.

Connecting Projects to Complete the In Situ Resource Utilization Paradigm

NASA Technical Reports Server (NTRS)

Linne, Diane L.; Sanders, Gerald B.

2017-01-01

Terrain Identify specifics such as slope, rockiness, traction parameters Identify what part of ISRU needs each Physical Geotechnical Hardness, density, cohesion, etc. Identify what part of ISRU needs each (e.g., excavation needs to know hardness, density; soil processing needs to know density, cohesion; etc.)Mineral Identify specifics Identify what part of ISRU needs each Volatile Identify specifics Identify what part of ISRU needs each Atmosphere Identify specifics Identify what part of ISRU needs each Environment Identify specifics Identify what part of ISRU needs each Resource Characterization What: Develop an instrument suite to locate and evaluate the physical, mineral, and volatile resources at the lunar poles Neutron Spectrometer Near Infrared (IR) to locate subsurface hydrogen surface water Near IR for mineral identification Auger drill for sample removal down to 1 m Oven with Gas Chromatograph Mass Spectrometer to quantify volatiles present ISRU relevance: Water volatile resource characterization and subsurface material access removal Site Evaluation Resource Mapping What: Develop and utilize new data products and tools for evaluating potential exploration sites for selection and overlay mission data to map terrain, environment, and resource information e.g., New techniques applied to generate Digital Elevation Map (DEMs) at native scale of images (1mpxl)ISRU relevance: Resource mapping and estimation with terrain and environment information is needed for extraction planning Mission Planning and Operations What: Develop and utilize tools and procedures for planning mission operations and real time changes Planning tools include detailed engineering models (e.g., power and data) of surface segment systems allows evaluation of designs ISRU relevance: Allows for iterative engineering as a function of environment and hardware performance.

Geophysical characterization of the role of fault and fracture systems for recharging groundwater aquifers from surface water of Lake Nasser

NASA Astrophysics Data System (ADS)

Mansour, Khamis; Omar, Khaled; Ali, Kamal; Abdel Zaher, Mohamed

2018-06-01

The role of the fracture system is important for enhancing the recharge or discharge of fluids in the subsurface reservoir. The Lake Nasser is consider one of the largest artificial lakes all over the world and contains huge bulk of storage water. In this study, the influence of fracture zones on subsurface fluid flow in groundwater reservoirs is investigated using geophysical techniques including seismicity, geoelectric and gravity data. These data have been utilized for exploring structural structure in south west Lake Nasser, and subsurface discontinuities (joints or faults) notwithstanding its related fracture systems. Seismicity investigation gave us the comprehension of the dynamic geological structure sets and proposing the main recharging paths for the Nubian aquifer from Lake Nasser surface water. Processing and modelling of aerogravity data show that the greater thickness of sedimentary cover (700 m) is located eastward and northward while basement outcrops occur at Umm Shaghir and Al Asr areas. Sixty-nine vertical electrical soundings (VES's) were used to delineate the subsurface geoelectric layers along eight profiles that help to realize the subsurface geological structure behind the hydrogeological conditions of the studied area.

Evaluation of positron emission tomography as a method to visualize subsurface microbial processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinsella K.; Schlyer D.; Kinsella, K.

2012-01-18

Positron emission tomography (PET) provides spatiotemporal monitoring in a nondestructive manner and has higher sensitivity and resolution relative to other tomographic methods. Therefore, this technology was evaluated for its application to monitor in situ subsurface bacterial activity. To date, however, it has not been used to monitor or image soil microbial processes. In this study, PET imaging was applied as a 'proof-of-principle' method to assess the feasibility of visualizing a radiotracer labeled subsurface bacterial strain (Rahnella sp. Y9602), previously isolated from uranium contaminated soils and shown to promote uranium phosphate precipitation. Soil columns packed with acid-purified simulated mineral soils weremore » seeded with 2-deoxy-2-[{sup 18}F]fluoro-d-glucose ({sup 18}FDG) labeled Rahnella sp. Y9602. The applicability of [{sup 18}F]fluoride ion as a tracer for measuring hydraulic conductivity and {sup 18}FDG as a tracer to identify subsurface metabolically active bacteria was successful in our soil column studies. Our findings indicate that positron-emitting isotopes can be utilized for studies aimed at elucidating subsurface microbiology and geochemical processes important in contaminant remediation.« less

Investigation of Zerodur material processing

NASA Technical Reports Server (NTRS)

Johnson, R. Barry

1993-01-01

The Final Report of the Center for Applied Optics (CAO), of The University of Alabama (UAH) study entitled 'Investigation of Zerodur Material Processing' is presented. The objectives of the effort were to prepare glass samples by cutting, grinding, etching, and polishing block Zerodur to desired specifications using equipment located in the optical shop located in the Optical System Branch at NASA/MSFC; characterize samples for subsurface damage and surface roughness; utilize Zerodur samples for coating investigations; and perform investigations into enhanced optical fabrication and metrology techniques. The results of this investigation will be used to support the Advanced X Ray Astrophysics Facility (AXAF) program as well as other NASA/MSFC research programs. The results of the technical effort are presented and discussed.

Bacterial carbon utilization in vertical subsurface flow constructed wetlands.

PubMed

Tietz, Alexandra; Langergraber, Günter; Watzinger, Andrea; Haberl, Raimund; Kirschner, Alexander K T

2008-03-01

Subsurface vertical flow constructed wetlands with intermittent loading are considered as state of the art and can comply with stringent effluent requirements. It is usually assumed that microbial activity in the filter body of constructed wetlands, responsible for the removal of carbon and nitrogen, relies mainly on bacterially mediated transformations. However, little quantitative information is available on the distribution of bacterial biomass and production in the "black-box" constructed wetland. The spatial distribution of bacterial carbon utilization, based on bacterial (14)C-leucine incorporation measurements, was investigated for the filter body of planted and unplanted indoor pilot-scale constructed wetlands, as well as for a planted outdoor constructed wetland. A simple mass-balance approach was applied to explain the bacterially catalysed organic matter degradation in this system by comparing estimated bacterial carbon utilization rates with simultaneously measured carbon reduction values. The pilot-scale constructed wetlands proved to be a suitable model system for investigating microbial carbon utilization in constructed wetlands. Under an ideal operating mode, the bulk of bacterial productivity occurred within the first 10cm of the filter body. Plants seemed to have no significant influence on productivity and biomass of bacteria, as well as on wastewater total organic carbon removal.

Microstructure-property relationships and constitutive response of plastically graded case hardened steels

NASA Astrophysics Data System (ADS)

Klecka, Michael A.

Case hardened materials, popularly used in many demanding engineering applications such as bearings, gears, and wear/impact surfaces, have high surface hardness and a gradient in material properties (hardness, yield strength, etc.) as a function of depth; therefore, they behave as plastically graded materials. In the current study, two different commercially available case carburized steels along with two through hardened steels are characterized to obtain relationships among the volume fraction of subsurface carbides, indentation hardness, elastic modulus, and yield strength as a function of depth. A variety of methods including microindentation, nanoindentation, ultrasonic measurements, compression testing, rule of mixtures, and upper and lower bound models are used to determine the relationships for elastic modulus and compare the experimental results with model predictions. In addition, the morphology, composition, and properties of the carbide particles are also determined. The gradient in hardness with depth in graded materials is commonly determined using microindentation on the cross-section of the material which contains the gradation in microstructure or composition. In the current study, a novel method is proposed to predict the hardness gradient profile using solely surface indentations at a range of loads. The method does not require the graded material to be sectioned, and has practical utility in the surface heat-treatment industry. For a material with a decreasing gradient in hardness, higher indent loads result in a lower measured hardness due to the influence of the softer subsurface layers. A power-law model is presented which relates the measured surface indentation hardness under increasing load to the subsurface gradient in hardness. A coordinated experimental and numerical study is presented to extract the constitutive response of graded materials, utilizing relationships between hardness, plastic deformation, and strain hardening response. The average plastic strain induced by an indent is shown to be an effective measure of the representative plastic strain, which is used in order to relate hardness to yield strength in both virgin and plastically deformed materials. It is shown that the two carburized steels contain gradients in yield strength, but constant strain hardening exponent with depth. The resulting model of material behavior is used to characterize the influence of specific gradients in material properties on the surface indentation behavior under increasing indentation loads. It is also shown that the response of the material is not greatly influenced by strain hardening exponent, while a gradient in strain hardening ability only has minimal impact. Gradients in elastic properties are also shown to have negligible influence for a fixed gradient in hardness. The depth of subsurface plastic deformation is shown to increase with sharper gradients in hardness, but is not altered by gradients in elastic properties. The proposed approach is not specific to case hardened materials and can be used to determine the subsurface hardness gradient for any graded material.

The genome of Geobacter bemidjiensis, exemplar for the subsurface clade of Geobacter species that predominate in Fe(III)-reducing subsurface environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aklujkar, Muktak; Young, Nelson D; Holmes, Dawn

2010-01-01

Background. Geobacter species in a phylogenetic cluster known as subsurface clade 1 are often the predominant microorganisms in subsurface environments in which Fe(III) reduction is the primary electron-accepting process. Geobacter bemidjiensis, a member of this clade, was isolated from hydrocarbon-contaminated subsurface sediments in Bemidji, Minnesota, and is closely related to Geobacter species found to be abundant at other subsurface sites. This study examines whether there are significant differences in the metabolism and physiology of G. bemidjiensis compared to non-subsurface Geobacter species. Results. Annotation of the genome sequence of G. bemidjiensis indicates several differences in metabolism compared to previously sequenced non-subsurfacemore » Geobacteraceae, which will be useful for in silico metabolic modeling of subsurface bioremediation processes involving Geobacter species. Pathways can now be predicted for the use of various carbon sources such as propionate by G. bemidjiensis. Additional metabolic capabilities such as carbon dioxide fixation and growth on glucose were predicted from the genome annotation. The presence of different dicarboxylic acid transporters and two oxaloacetate decarboxylases in G. bemidjiensis may explain its ability to grow by disproportionation of fumarate. Although benzoate is the only aromatic compound that G. bemidjiensis is known or predicted to utilize as an electron donor and carbon source, the genome suggests that this species may be able to detoxify other aromatic pollutants without degrading them. Furthermore, G. bemidjiensis is auxotrophic for 4-aminobenzoate, which makes it the first Geobacter species identified as having a vitamin requirement. Several features of the genome indicated that G. bemidjiensis has enhanced abilities to respire, detoxify and avoid oxygen. Conclusion. Overall, the genome sequence of G. bemidjiensis offers surprising insights into the metabolism and physiology of Geobacteraceae in subsurface environments, compared to non-subsurface Geobacter species, such as the ability to disproportionate fumarate, more efficient oxidation of propionate, enhanced responses to oxygen stress, and dependence on the environment for a vitamin requirement. Therefore, an understanding of the activity of Geobacter species in the subsurface is more likely to benefit from studies of subsurface isolates such as G. bemidjiensis than from the non-subsurface model species studied so far.« less

Investigations of potential microbial methanogenic and carbon monoxide utilization pathways in ultra-basic reducing springs associated with present-day continental serpentinization: the Tablelands, NL, CAN

PubMed Central

Morrill, Penny L.; Brazelton, William J.; Kohl, Lukas; Rietze, Amanda; Miles, Sarah M.; Kavanagh, Heidi; Schrenk, Matthew O.; Ziegler, Susan E.; Lang, Susan Q.

2014-01-01

Ultra-basic reducing springs at continental sites of serpentinization act as portals into the biogeochemistry of a subsurface environment with H2 and CH4 present. Very little, however, is known about the carbon substrate utilization, energy sources, and metabolic pathways of the microorganisms that live in this ultra-basic environment. The potential for microbial methanogenesis with bicarbonate, formate, acetate, and propionate precursors and carbon monoxide (CO) utilization pathways were tested in laboratory experiments by adding substrates to water and sediment from the Tablelands, NL, CAD, a site of present-day continental serpentinization. Microbial methanogenesis was not observed after bicarbonate, formate, acetate, or propionate addition. CO was consumed in the live experiments but not in the killed controls and the residual CO in the live experiments became enriched in 13C. The average isotopic enrichment factor resulting from this microbial utilization of CO was estimated to be 11.2 ± 0.2‰. Phospholipid fatty acid concentrations and δ13C values suggest limited incorporation of carbon from CO into microbial lipids. This indicates that in our experiments, CO was used primarily as an energy source, but not for biomass growth. Environmental DNA sequencing of spring fluids collected at the same time as the addition experiments yielded a large proportion of Hydrogenophaga-related sequences, which is consistent with previous metagenomic data indicating the potential for these taxa to utilize CO. PMID:25431571

Investigations of potential microbial methanogenic and carbon monoxide utilization pathways in ultra-basic reducing springs associated with present-day continental serpentinization: the Tablelands, NL, CAN.

PubMed

Morrill, Penny L; Brazelton, William J; Kohl, Lukas; Rietze, Amanda; Miles, Sarah M; Kavanagh, Heidi; Schrenk, Matthew O; Ziegler, Susan E; Lang, Susan Q

2014-01-01

Ultra-basic reducing springs at continental sites of serpentinization act as portals into the biogeochemistry of a subsurface environment with H2 and CH4 present. Very little, however, is known about the carbon substrate utilization, energy sources, and metabolic pathways of the microorganisms that live in this ultra-basic environment. The potential for microbial methanogenesis with bicarbonate, formate, acetate, and propionate precursors and carbon monoxide (CO) utilization pathways were tested in laboratory experiments by adding substrates to water and sediment from the Tablelands, NL, CAD, a site of present-day continental serpentinization. Microbial methanogenesis was not observed after bicarbonate, formate, acetate, or propionate addition. CO was consumed in the live experiments but not in the killed controls and the residual CO in the live experiments became enriched in (13)C. The average isotopic enrichment factor resulting from this microbial utilization of CO was estimated to be 11.2 ± 0.2‰. Phospholipid fatty acid concentrations and δ(13)C values suggest limited incorporation of carbon from CO into microbial lipids. This indicates that in our experiments, CO was used primarily as an energy source, but not for biomass growth. Environmental DNA sequencing of spring fluids collected at the same time as the addition experiments yielded a large proportion of Hydrogenophaga-related sequences, which is consistent with previous metagenomic data indicating the potential for these taxa to utilize CO.

Robust Representation of Integrated Surface-subsurface Hydrology at Watershed Scales

NASA Astrophysics Data System (ADS)

Painter, S. L.; Tang, G.; Collier, N.; Jan, A.; Karra, S.

2015-12-01

A representation of integrated surface-subsurface hydrology is the central component to process-rich watershed models that are emerging as alternatives to traditional reduced complexity models. These physically based systems are important for assessing potential impacts of climate change and human activities on groundwater-dependent ecosystems and water supply and quality. Integrated surface-subsurface models typically couple three-dimensional solutions for variably saturated flow in the subsurface with the kinematic- or diffusion-wave equation for surface flows. The computational scheme for coupling the surface and subsurface systems is key to the robustness, computational performance, and ease-of-implementation of the integrated system. A new, robust approach for coupling the subsurface and surface systems is developed from the assumption that the vertical gradient in head is negligible at the surface. This tight-coupling assumption allows the surface flow system to be incorporated directly into the subsurface system; effects of surface flow and surface water accumulation are represented as modifications to the subsurface flow and accumulation terms but are not triggered until the subsurface pressure reaches a threshold value corresponding to the appearance of water on the surface. The new approach has been implemented in the highly parallel PFLOTRAN (www.pflotran.org) code. Several synthetic examples and three-dimensional examples from the Walker Branch Watershed in Oak Ridge TN demonstrate the utility and robustness of the new approach using unstructured computational meshes. Representation of solute transport in the new approach is also discussed. Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes.

Energy Requirements of Hydrogen-utilizing Microbes: A Boundary Condition for Subsurface Life

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Alperin, Marc J.; Albert, Daniel B.; Martens, Christopher S.

2003-01-01

Microbial ecosystems based on the energy supplied by water-rock chemistry carry particular significance in the context of geo- and astrobiology. With no direct dependence on solar energy, lithotrophic microbes could conceivably penetrate a planetary crust to a depth limited only by temperature or pressure constraints (several kilometers or more). The deep lithospheric habitat is thereby potentially much greater in volume than its surface counterpart, and in addition offers a stable refuge against inhospitable surface conditions related to climatic or atmospheric evolution (e.g., Mars) or even high-energy impacts (e.g., early in Earth's history). The possibilities for a deep microbial biosphere are, however, greatly constrained by life s need to obtain energy at a certain minimum rate (the maintenance energy requirement) and of a certain minimum magnitude (the energy quantum requirement). The mere existence of these requirements implies that a significant fraction of the chemical free energy available in the subsurface environment cannot be exploited by life. Similar limits may also apply to the usefulness of light energy at very low intensities or long wavelengths. Quantification of these minimum energy requirements in terrestrial microbial ecosystems will help to establish a criterion of energetic habitability that can significantly constrain the prospects for life in Earth's subsurface, or on other bodies in the solar system. Our early work has focused on quantifying the biological energy quantum requirement for methanogenic archaea, as representatives of a plausible subsurface metabolism, in anoxic sediments (where energy availability is among the most limiting factors in microbial population growth). In both field and laboratory experiments utilizing these sediments, methanogens retain a remarkably consistent free energy intake, in the face of fluctuating environmental conditions that affect energy availability. The energy yields apparently required by methanogens in these sediment systems for sustained metabolism are about half that previously thought necessary. Lowered energy requirements would imply that a correspondingly greater proportion of the planetary subsurface could represent viable habitat for microorganisms.

Extremely high resolution 3D electrical resistivity tomography to depict archaeological subsurface structures

NASA Astrophysics Data System (ADS)

Al-Saadi, Osamah; Schmidt, Volkmar; Becken, Michael; Fritsch, Thomas

2017-04-01

Electrical resistivity tomography (ERT) methods have been increasingly used in various shallow depth archaeological prospections in the last few decades. These non-invasive techniques are very useful in saving time, costs, and efforts. Both 2D and 3D ERT techniques are used to obtain detailed images of subsurface anomalies. In two surveyed areas near Nonnweiler (Germany), we present the results of the full 3D setup with a roll-along technique and of the quasi-3D setup (parallel and orthogonal profiles in dipole-dipole configuration). In area A, a dipole-dipole array with 96 electrodes in a uniform rectangular survey grid has been used in full 3D to investigate a presumed Roman building. A roll-along technique has been utilized to cover a large part of the archaeological site with an electrode spacing of 1 meter and with 0.5 meter for a more detailed image. Additional dense parallel 2D profiles have been carried out in dipole-dipole array with 0.25 meter electrode spacing and 0.25 meter between adjacent profiles in both direction for higher- resolution subsurface images. We have designed a new field procedure, which used an electrode array fixed in a frame. This facilitates efficient field operation, which comprised 2376 electrode positions. With the quasi 3D imaging, we confirmed the full 3D inversion model but at a much better resolution. In area B, dense parallel 2D profiles were directly used to survey the second target with also 0.25 meter electrode spacing and profiles separation respectively. The same field measurement design has been utilized and comprised 9648 electrode positions in total. The quasi-3D inversion results clearly revealed the main structures of the Roman construction. These ERT inversion results coincided well with the archaeological excavation, which has been done in some parts of this area. The ERT result successfully images parts from the walls and also smaller internal structures of the Roman building.

Inverse geothermal modelling applied to Danish sedimentary basins

NASA Astrophysics Data System (ADS)

Poulsen, Søren E.; Balling, Niels; Bording, Thue S.; Mathiesen, Anders; Nielsen, Søren B.

2017-10-01

This paper presents a numerical procedure for predicting subsurface temperatures and heat-flow distribution in 3-D using inverse calibration methodology. The procedure is based on a modified version of the groundwater code MODFLOW by taking advantage of the mathematical similarity between confined groundwater flow (Darcy's law) and heat conduction (Fourier's law). Thermal conductivity, heat production and exponential porosity-depth relations are specified separately for the individual geological units of the model domain. The steady-state temperature model includes a model-based transient correction for the long-term palaeoclimatic thermal disturbance of the subsurface temperature regime. Variable model parameters are estimated by inversion of measured borehole temperatures with uncertainties reflecting their quality. The procedure facilitates uncertainty estimation for temperature predictions. The modelling procedure is applied to Danish onshore areas containing deep sedimentary basins. A 3-D voxel-based model, with 14 lithological units from surface to 5000 m depth, was built from digital geological maps derived from combined analyses of reflection seismic lines and borehole information. Matrix thermal conductivity of model lithologies was estimated by inversion of all available deep borehole temperature data and applied together with prescribed background heat flow to derive the 3-D subsurface temperature distribution. Modelled temperatures are found to agree very well with observations. The numerical model was utilized for predicting and contouring temperatures at 2000 and 3000 m depths and for two main geothermal reservoir units, the Gassum (Lower Jurassic-Upper Triassic) and Bunter/Skagerrak (Triassic) reservoirs, both currently utilized for geothermal energy production. Temperature gradients to depths of 2000-3000 m are generally around 25-30 °C km-1, locally up to about 35 °C km-1. Large regions have geothermal reservoirs with characteristic temperatures ranging from ca. 40-50 °C, at 1000-1500 m depth, to ca. 80-110 °C, at 2500-3500 m, however, at the deeper parts, most likely, with too low permeability for non-stimulated production.

Integrating surrogate models into subsurface simulation framework allows computation of complex reactive transport scenarios

NASA Astrophysics Data System (ADS)

De Lucia, Marco; Kempka, Thomas; Jatnieks, Janis; Kühn, Michael

2017-04-01

Reactive transport simulations - where geochemical reactions are coupled with hydrodynamic transport of reactants - are extremely time consuming and suffer from significant numerical issues. Given the high uncertainties inherently associated with the geochemical models, which also constitute the major computational bottleneck, such requirements may seem inappropriate and probably constitute the main limitation for their wide application. A promising way to ease and speed-up such coupled simulations is achievable employing statistical surrogates instead of "full-physics" geochemical models [1]. Data-driven surrogates are reduced models obtained on a set of pre-calculated "full physics" simulations, capturing their principal features while being extremely fast to compute. Model reduction of course comes at price of a precision loss; however, this appears justified in presence of large uncertainties regarding the parametrization of geochemical processes. This contribution illustrates the integration of surrogates into the flexible simulation framework currently being developed by the authors' research group [2]. The high level language of choice for obtaining and dealing with surrogate models is R, which profits from state-of-the-art methods for statistical analysis of large simulations ensembles. A stand-alone advective mass transport module was furthermore developed in order to add such capability to any multiphase finite volume hydrodynamic simulator within the simulation framework. We present 2D and 3D case studies benchmarking the performance of surrogates and "full physics" chemistry in scenarios pertaining the assessment of geological subsurface utilization. [1] Jatnieks, J., De Lucia, M., Dransch, D., Sips, M.: "Data-driven surrogate model approach for improving the performance of reactive transport simulations.", Energy Procedia 97, 2016, p. 447-453. [2] Kempka, T., Nakaten, B., De Lucia, M., Nakaten, N., Otto, C., Pohl, M., Chabab [Tillner], E., Kühn, M.: "Flexible Simulation Framework to Couple Processes in Complex 3D Models for Subsurface Utilization Assessment.", Energy Procedia, 97, 2016 p. 494-501.

RESOLVE Mission Architecture for Lunar Resource Prospecting and Utilization

NASA Technical Reports Server (NTRS)

George, J. A.; Mattes, G. W.; Rogers, K. N.; Magruder, D. F.; Paz, A. J.; Vaccaro, H. M.; Baird, R. S.; Sanders, G. B.; Smith, J. T.; Quinn, J. W.;

Evidence of remediation-induced alteration of subsurface poly- and perfluoroalkyl substance distribution at a former firefighter training area.

PubMed

McGuire, Meghan E; Schaefer, Charles; Richards, Trenton; Backe, Will J; Field, Jennifer A; Houtz, Erika; Sedlak, David L; Guelfo, Jennifer L; Wunsch, Assaf; Higgins, Christopher P

2014-06-17

Poly- and perfluoroalkyl substances (PFASs) are a class of fluorinated chemicals that are utilized in firefighting and have been reported in groundwater and soil at several firefighter training areas. In this study, soil and groundwater samples were collected from across a former firefighter training area to examine the extent to which remedial activities have altered the composition and spatial distribution of PFASs in the subsurface. Log Koc values for perfluoroalkyl acids (PFAAs), estimated from analysis of paired samples of groundwater and aquifer solids, indicated that solid/water partitioning was not entirely consistent with predictions based on laboratory studies. Differential PFAA transport was not strongly evident in the subsurface, likely due to remediation-induced conditions. When compared to the surface soil spatial distributions, the relative concentrations of perfluorooctanesulfonate (PFOS) and PFAA precursors in groundwater strongly suggest that remedial activities altered the subsurface PFAS distribution, presumably through significant pumping of groundwater and transformation of precursors to PFAAs. Additional evidence for transformation of PFAA precursors during remediation included elevated ratios of perfluorohexanesulfonate (PFHxS) to PFOS in groundwater near oxygen sparging wells.

Advances in interpretation of subsurface processes with time-lapse electrical imaging

USGS Publications Warehouse

Singha, Kaminit; Day-Lewis, Frederick D.; Johnson, Tim B.; Slater, Lee D.

2015-01-01

Electrical geophysical methods, including electrical resistivity, time-domain induced polarization, and complex resistivity, have become commonly used to image the near subsurface. Here, we outline their utility for time-lapse imaging of hydrological, geochemical, and biogeochemical processes, focusing on new instrumentation, processing, and analysis techniques specific to monitoring. We review data collection procedures, parameters measured, and petrophysical relationships and then outline the state of the science with respect to inversion methodologies, including coupled inversion. We conclude by highlighting recent research focused on innovative applications of time-lapse imaging in hydrology, biology, ecology, and geochemistry, among other areas of interest.

Advances in interpretation of subsurface processes with time-lapse electrical imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singha, Kamini; Day-Lewis, Frederick D.; Johnson, Timothy C.

2015-03-15

Electrical geophysical methods, including electrical resistivity, time-domain induced polarization, and complex resistivity, have become commonly used to image the near subsurface. Here, we outline their utility for time-lapse imaging of hydrological, geochemical, and biogeochemical processes, focusing on new instrumentation, processing, and analysis techniques specific to monitoring. We review data collection procedures, parameters measured, and petrophysical relationships and then outline the state of the science with respect to inversion methodologies, including coupled inversion. We conclude by highlighting recent research focused on innovative applications of time-lapse imaging in hydrology, biology, ecology, and geochemistry, among other areas of interest.

Evaluation of consolidation characteristics of cohesive soils from piezocone penetration tests.

DOT National Transportation Integrated Search

2004-01-01

The piezocone penetration test (PCPT) has gained wide popularity and acknowledgement as a preferred in-situ device for subsurface investigation and soil characterization. The PCPT measurements can be utilized for soil identification and the evaluatio...

Effect of gold subsurface layer on the surface activity and segregation in Pt/Au/Pt3M (where M = 3d transition metals) alloy catalyst from first-principles.

PubMed

Kim, Chang-Eun; Lim, Dong-Hee; Jang, Jong Hyun; Kim, Hyoung Juhn; Yoon, Sung Pil; Han, Jonghee; Nam, Suk Woo; Hong, Seong-Ahn; Soon, Aloysius; Ham, Hyung Chul

2015-01-21

The effect of a subsurface hetero layer (thin gold) on the activity and stability of Pt skin surface in Pt3M system (M = 3d transition metals) is investigated using the spin-polarized density functional theory calculation. First, we find that the heterometallic interaction between the Pt skin surface and the gold subsurface in Pt/Au/Pt3M system can significantly modify the electronic structure of the Pt skin surface. In particular, the local density of states projected onto the d states of Pt skin surface near the Fermi level is drastically decreased compared to the Pt/Pt/Pt3M case, leading to the reduction of the oxygen binding strength of the Pt skin surface. This modification is related to the increase of surface charge polarization of outmost Pt skin atoms by the electron transfer from the gold subsurface atoms. Furthermore, a subsurface gold layer is found to cast the energetic barrier to the segregation loss of metal atoms from the bulk (inside) region, which can enhance the durability of Pt3M based catalytic system in oxygen reduction condition at fuel cell devices. This study highlights that a gold subsurface hetero layer can provide an additional mean to tune the surface activity toward oxygen species and in turn the oxygen reduction reaction, where the utilization of geometric strain already reaches its practical limit.

Identification and Removal of Contaminant Sequences From Ribosomal Gene Databases: Lessons From the Census of Deep Life

PubMed Central

Sheik, Cody S.; Reese, Brandi Kiel; Twing, Katrina I.; Sylvan, Jason B.; Grim, Sharon L.; Schrenk, Matthew O.; Sogin, Mitchell L.; Colwell, Frederick S.

2018-01-01

Earth’s subsurface environment is one of the largest, yet least studied, biomes on Earth, and many questions remain regarding what microorganisms are indigenous to the subsurface. Through the activity of the Census of Deep Life (CoDL) and the Deep Carbon Observatory, an open access 16S ribosomal RNA gene sequence database from diverse subsurface environments has been compiled. However, due to low quantities of biomass in the deep subsurface, the potential for incorporation of contaminants from reagents used during sample collection, processing, and/or sequencing is high. Thus, to understand the ecology of subsurface microorganisms (i.e., the distribution, richness, or survival), it is necessary to minimize, identify, and remove contaminant sequences that will skew the relative abundances of all taxa in the sample. In this meta-analysis, we identify putative contaminants associated with the CoDL dataset, recommend best practices for removing contaminants from samples, and propose a series of best practices for subsurface microbiology sampling. The most abundant putative contaminant genera observed, independent of evenness across samples, were Propionibacterium, Aquabacterium, Ralstonia, and Acinetobacter. While the top five most frequently observed genera were Pseudomonas, Propionibacterium, Acinetobacter, Ralstonia, and Sphingomonas. The majority of the most frequently observed genera (high evenness) were associated with reagent or potential human contamination. Additionally, in DNA extraction blanks, we observed potential archaeal contaminants, including methanogens, which have not been discussed in previous contamination studies. Such contaminants would directly affect the interpretation of subsurface molecular studies, as methanogenesis is an important subsurface biogeochemical process. Utilizing previously identified contaminant genera, we found that ∼27% of the total dataset were identified as contaminant sequences that likely originate from DNA extraction and DNA cleanup methods. Thus, controls must be taken at every step of the collection and processing procedure when working with low biomass environments such as, but not limited to, portions of Earth’s deep subsurface. Taken together, we stress that the CoDL dataset is an incredible resource for the broader research community interested in subsurface life, and steps to remove contamination derived sequences must be taken prior to using this dataset. PMID:29780369

Identification and Removal of Contaminant Sequences From Ribosomal Gene Databases: Lessons From the Census of Deep Life.

PubMed

Sheik, Cody S; Reese, Brandi Kiel; Twing, Katrina I; Sylvan, Jason B; Grim, Sharon L; Schrenk, Matthew O; Sogin, Mitchell L; Colwell, Frederick S

2018-01-01

Earth's subsurface environment is one of the largest, yet least studied, biomes on Earth, and many questions remain regarding what microorganisms are indigenous to the subsurface. Through the activity of the Census of Deep Life (CoDL) and the Deep Carbon Observatory, an open access 16S ribosomal RNA gene sequence database from diverse subsurface environments has been compiled. However, due to low quantities of biomass in the deep subsurface, the potential for incorporation of contaminants from reagents used during sample collection, processing, and/or sequencing is high. Thus, to understand the ecology of subsurface microorganisms (i.e., the distribution, richness, or survival), it is necessary to minimize, identify, and remove contaminant sequences that will skew the relative abundances of all taxa in the sample. In this meta-analysis, we identify putative contaminants associated with the CoDL dataset, recommend best practices for removing contaminants from samples, and propose a series of best practices for subsurface microbiology sampling. The most abundant putative contaminant genera observed, independent of evenness across samples, were Propionibacterium , Aquabacterium , Ralstonia , and Acinetobacter . While the top five most frequently observed genera were Pseudomonas , Propionibacterium , Acinetobacter , Ralstonia , and Sphingomonas . The majority of the most frequently observed genera (high evenness) were associated with reagent or potential human contamination. Additionally, in DNA extraction blanks, we observed potential archaeal contaminants, including methanogens, which have not been discussed in previous contamination studies. Such contaminants would directly affect the interpretation of subsurface molecular studies, as methanogenesis is an important subsurface biogeochemical process. Utilizing previously identified contaminant genera, we found that ∼27% of the total dataset were identified as contaminant sequences that likely originate from DNA extraction and DNA cleanup methods. Thus, controls must be taken at every step of the collection and processing procedure when working with low biomass environments such as, but not limited to, portions of Earth's deep subsurface. Taken together, we stress that the CoDL dataset is an incredible resource for the broader research community interested in subsurface life, and steps to remove contamination derived sequences must be taken prior to using this dataset.

Identification and characterization of natural pipe systems in forested tropical soils

NASA Astrophysics Data System (ADS)

Bovi, Renata Cristina; Moreira, Cesar Augusto; Stucchi Boschi, Raquel; Cooper, Miguel

2017-04-01

Erosive processes on soil surface have been well studied and comprehended by several researchers, however little is known about subsurface erosive processes (piping). Piping is a type of subsurface erosion caused by water flowing in the subsurface and is still considered one of the most difficult erosive processes to be studied. Several processes have been considered as resposible for subsurface erosion and their interaction is complex and difficult to be studied separately. Surface investigations on their own may underestimate the erosion processes, due to the possible occurrence of subsurface processes that are not yet exposed on the surface. The network of subsurface processes should also be understood to better control erosion. Conservation practices that focus on water runoff control may be inefficient if the subsurface flow is not considered. In this study, we aimed to identify and characterize subsurface cavities in the field, as well as understand the network of these cavities, by using geophysical methods (electrical tomography). The study area is situated at the Experimental Station of Tupi, state of São Paulo, Brazil. The soil of the area was classified as Hapludults. The area presents several erosive features, ranging from laminar to permanent gullies and subsurface erosions. The geophysical equipment used was the Terrameter LS resistivity meter, manufactured by ABEM Instruments. The method of electrical tomography was efficient to detect collapsed and non-collapsed pipes. The results presented valuable information to detect areas of risk.

A combined joint diagonalization-MUSIC algorithm for subsurface targets localization

NASA Astrophysics Data System (ADS)

Wang, Yinlin; Sigman, John B.; Barrowes, Benjamin E.; O'Neill, Kevin; Shubitidze, Fridon

2014-06-01

This paper presents a combined joint diagonalization (JD) and multiple signal classification (MUSIC) algorithm for estimating subsurface objects locations from electromagnetic induction (EMI) sensor data, without solving ill-posed inverse-scattering problems. JD is a numerical technique that finds the common eigenvectors that diagonalize a set of multistatic response (MSR) matrices measured by a time-domain EMI sensor. Eigenvalues from targets of interest (TOI) can be then distinguished automatically from noise-related eigenvalues. Filtering is also carried out in JD to improve the signal-to-noise ratio (SNR) of the data. The MUSIC algorithm utilizes the orthogonality between the signal and noise subspaces in the MSR matrix, which can be separated with information provided by JD. An array of theoreticallycalculated Green's functions are then projected onto the noise subspace, and the location of the target is estimated by the minimum of the projection owing to the orthogonality. This combined method is applied to data from the Time-Domain Electromagnetic Multisensor Towed Array Detection System (TEMTADS). Examples of TEMTADS test stand data and field data collected at Spencer Range, Tennessee are analyzed and presented. Results indicate that due to its noniterative mechanism, the method can be executed fast enough to provide real-time estimation of objects' locations in the field.

Factors Effecting the Fate and Transport of CL-20 in the Vadose Zone and Groundwater: Final Report 2002 - 2004 SERDP Project CP-1255

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szecsody, James E.; Riley, Robert G.; Devary, Brooks J.

2005-06-01

This SERDP-funded project was initiated to investigate the fate of CL-20 in the subsurface environment, with a focus on identification and quantification of geochemical and microbial reactions of CL-20. CL-20 can be released to the surface and subsurface terrestrial environment by: a) manufacturing processes, b) munition storage, and c) use with low order detonation or unexploded ordnance. The risk of far-field subsurface migration was assessed through labora-tory experiments with a variety of sediments and subsurface materials to quantify processes that control CL-20 sorption-limited migration and degradation. Results of this study show that CL-20 will exhibit differing behavior in the subsurfacemore » terrestrial environment: 1. CL-20 on the sediment surface will photodegrade and interact with plants/animals (described in other SERDP projects CU 1254, 1256). CL-20 will exhibit greater sorption in humid sediments to organic matter. Transport will be solubility limited (i.e., low CL-20 aqueous solubility). 2. CL-20 infiltration into soils (<2 m) from spills will be subject to sorption to soil organic matter (if present), and low to high biodegradation rates (weeks to years) depending on the microbial population (greater in humid environment). 3. CL-20 in the vadose zone (>2 m) will be, in most cases, subject to low sorption and low degradation rates, so would persist in the subsurface environment and be at risk for deep migration. Low water content in arid regions will result in a decrease in both sorption and the degradation rate. Measured degradation rates in unsaturated sediments of years would result in significant subsurface migration distances. 4. CL-20 in groundwater will be subject to some sorption but likely very slow degradation rates. CL-20 sorption will be greater than RDX. Most CL-20 degradation will be abiotic (ferrous iron and other transition metals), because most deep subsurface systems have extremely low natural microbial populations. Degradation rates will range from weeks (iron reducing systems) to years. Although CL-20 will move rapidly through most sediments in the terrestrial environment, subsurface remediation can be utilized for cleanup. Transformation of CL-20 to intermediates can be rapidly accomplished under: a) reducing conditions (CL-20 4.1 min. half-life, RDX 18 min. half-life), b) alkaline (pH >10) conditions, and c) bioremediation with added nutrients. CL-20 degradation to intermediates may be insufficient to mitigate environmental impact, as the toxicity of many of these compounds is unknown. Biostimulation in oxic to reducing systems by carbon and nutrient addition can mineralize CL-20, with the most rapid rates occurring under reducing conditions.« less

Tidal Response of Europa's Subsurface Ocean

NASA Astrophysics Data System (ADS)

Karatekin, O.; Comblen, R.; Deleersnijder, E.; Dehant, V. M.

2010-12-01

Time-variable tides in the subsurface oceans of icy satellites cause large periodic surface displacements and tidal dissipation can become a major energy source that can affect long-term orbital and internal evolution. In the present study, we investigate the response of the subsurface ocean of Europa to a time-varibale tidal potential. Two-dimensional nonlinear shallow water equations are solved on a sphere by means of a finite element code. The resulting ocean tidal flow velocities,dissipation and surface displacements will be presented.

Workshop on Radar Investigations of Planetary and Terrestrial Environments

NASA Technical Reports Server (NTRS)

2005-01-01

Contents include the following: Salt Kinematics and InSAR. SAR Interferometry as a Tool for Monitoring Coastal Changes in the Nile River Delta of Egypt. Modem Radar Techniques for Geophysical Applications: Two Examples. WISDOM Experiment on the EXOMARS ESA Mission. An Ice Thickness Study Utilizing Ground Penetrating Radar on the Lower Jamapa. Probing the Martian Subsurface with Synthetic Aperture Radar. Planetary Surface Properties from Radar Polarimetric Observations. Imaging the Sub-surface Reflectors : Results From the RANETA/NETLANDER Field Test on the Antarctic Ice Shelf. Strategy for Selection of Mars Geophysical Analogue Sites. Observations of Low Frequency Low Altitude Plasma Oscillations at Mars and Implications for Electromagnetic Sounding of the Subsurface. Ionospheric Transmission Losses Associated with Mars-orbiting Radar. A Polarimetric Scattering Model for the 2-Layer Problem. Radars for Imaging and Sounding of Polar Ice Sheets. Strata: Ground Penetrating Radar for Mars Rovers. Scattering Limits to Depth of Radar Investigation: Lessons from the Bishop Tuff.

Experimental utilization of tire shreds to enhance highway drainage.

DOT National Transportation Integrated Search

2001-03-01

This project investigates the practical benefits of using shredded tires as a free draining material : in a subsurface French drain to enhance drainage along a section of highway. French drains are : below-grade structures designed to re-direct groun...

SPATIAL AND TEMPORAL GRADIENTS IN AQUIFER OXIDATION- REDUCTION CONDITIONS

EPA Science Inventory

The study was undertaken to identify principal oxidizing and reducing chemical species in groundwater with the goal of determining the utility of platinum electrode (Eh) measurements to characterize subsurface redox conditions. Serial measurements of Eh and groundwater analyses w...

Peeking Beneath the Caldera: Communicating Subsurface Knowledge of Newberry Volcano

NASA Astrophysics Data System (ADS)

Mark-Moser, M.; Rose, K.; Schultz, J.; Cameron, E.

2016-12-01

"Imaging the Subsurface: Enhanced Geothermal Systems and Exploring Beneath Newberry Volcano" is an interactive website that presents a three-dimensional subsurface model of Newberry Volcano developed at National Energy Technology Laboratory (NETL). Created using the Story Maps application by ArcGIS Online, this format's dynamic capabilities provide the user the opportunity for multimedia engagement with the datasets and information used to build the subsurface model. This website allows for an interactive experience that the user dictates, including interactive maps, instructive videos and video capture of the subsurface model, and linked information throughout the text. This Story Map offers a general background on the technology of enhanced geothermal systems and the geologic and development history of Newberry Volcano before presenting NETL's modeling efforts that support the installation of enhanced geothermal systems. The model is driven by multiple geologic and geophysical datasets to compare and contrast results which allow for the targeting of potential EGS sites and the reduction of subsurface uncertainty. This Story Map aims to communicate to a broad audience, and provides a platform to effectively introduce the model to researchers and stakeholders.

Planetary science and exploration in the deep subsurface: results from the MINAR Program, Boulby Mine, UK

NASA Astrophysics Data System (ADS)

Payler, Samuel J.; Biddle, Jennifer F.; Coates, Andrew J.; Cousins, Claire R.; Cross, Rachel E.; Cullen, David C.; Downs, Michael T.; Direito, Susana O. L.; Edwards, Thomas; Gray, Amber L.; Genis, Jac; Gunn, Matthew; Hansford, Graeme M.; Harkness, Patrick; Holt, John; Josset, Jean-Luc; Li, Xuan; Lees, David S.; Lim, Darlene S. S.; McHugh, Melissa; McLuckie, David; Meehan, Emma; Paling, Sean M.; Souchon, Audrey; Yeoman, Louise; Cockell, Charles S.

2017-04-01

The subsurface exploration of other planetary bodies can be used to unravel their geological history and assess their habitability. On Mars in particular, present-day habitable conditions may be restricted to the subsurface. Using a deep subsurface mine, we carried out a program of extraterrestrial analog research - MINe Analog Research (MINAR). MINAR aims to carry out the scientific study of the deep subsurface and test instrumentation designed for planetary surface exploration by investigating deep subsurface geology, whilst establishing the potential this technology has to be transferred into the mining industry. An integrated multi-instrument suite was used to investigate samples of representative evaporite minerals from a subsurface Permian evaporite sequence, in particular to assess mineral and elemental variations which provide small-scale regions of enhanced habitability. The instruments used were the Panoramic Camera emulator, Close-Up Imager, Raman spectrometer, Small Planetary Linear Impulse Tool, Ultrasonic drill and handheld X-ray diffraction (XRD). We present science results from the analog research and show that these instruments can be used to investigate in situ the geological context and mineralogical variations of a deep subsurface environment, and thus habitability, from millimetre to metre scales. We also show that these instruments are complementary. For example, the identification of primary evaporite minerals such as NaCl and KCl, which are difficult to detect by portable Raman spectrometers, can be accomplished with XRD. By contrast, Raman is highly effective at locating and detecting mineral inclusions in primary evaporite minerals. MINAR demonstrates the effective use of a deep subsurface environment for planetary instrument development, understanding the habitability of extreme deep subsurface environments on Earth and other planetary bodies, and advancing the use of space technology in economic mining.

Deep subsurface microbiology of 64-71 million year old inactive seamounts along the Louisville Seamount Chain

NASA Astrophysics Data System (ADS)

Sylvan, J. B.; Morono, Y.; Grim, S.; Inagaki, F.; Edwards, K. J.

2013-12-01

One of the objectives of IODP Expedition 330, Louisville Seamount Trail, was to sample and learn about the subsurface biosphere in the Louisville Seamount Chain (LSC). Seamounts are volcanic constructs that are ubiquitous along the seafloor - models suggest there are >100,000 seamounts of >1 km in height globally (Wessel et al., 2010). Therefore, knowledge about microbiology in the LSC subsurface can broadly be interpreted as representative of much the seafloor. In addition, despite the fact that the vast majority of the sea floor is comprised of crust >10 Ma, the majority of work to date has focused on young sites with active hydrology. Our presentation summarizes work focusing on subsurface microbiology from two different LSC seamounts: holes U1374A (65-71 Ma) and U1376A (64 Ma). We here present data for microbial biomass in the LSC subsurface using a method we developed to quantify microbial biomass in subseafloor ocean crust. We also present results from pyrotag analysis of 15 samples from holes U1374A and holes U1376A, representing several different lithologies from 40-491 meters below seafloor (mbsf) in hole U1374A and from 29-174 mbsf in hole U1376A. Finally, we present preliminary analysis of metagenomic sequencing from three of the samples from Hole U1376A. Biomass was low in the subsurface of both seamounts, ranging from below detection to ~104 cells cm-3. Bacteria comprised >99% of the prokaryotic community in LSC subsurface samples, therefore, bacterial diversity was assessed through 454 pyrosequencing of the V4V6 region of the 16S rRNA gene. Rarefaction analysis indicates that bacterial communities from the LSC subsurface are low diversity, on the order of a few hundred operational taxonomic units per sample. The phyla Actinobacteria, Bacteroidetes, Firmicutes and the classes α-, β- and γ-Proteobacteria are most abundant in the LSC subsurface. Within these, the orders Actinomycetales, Sphingobacteriales, Bacillales and Burkholderiales are the most common. Samples from different lithologies in hole U1374A grouped together, indicating more similarity to each other than to samples from hole U1376A. However, samples from different lithologies in hole U1376A were not similar to other samples from the same site, indicating some differences in the microbial communities between the two seamounts. Preliminary analysis of the metagenomic data will provide further assessment of community structure and reveal likely metabolisms present in the LSC subsurface. Altogether, the biomass data, pyrotag analysis and metagenomic sequencing provide a well-balanced analysis of subsurface microbiology in an old oceanic crustal environment. Wessel, P., Sandwell, D. T. & Kim, S. S. (2010). The Global Seamount Census. Oceanography 23, 24-33.

Structural analysis of lunar subsurface with Chang'E-3 lunar penetrating radar

NASA Astrophysics Data System (ADS)

Lai, Jialong; Xu, Yi; Zhang, Xiaoping; Tang, Zesheng

2016-01-01

Geological structure of the subsurface of the Moon provides valuable information on lunar evolution. Recently, Chang'E-3 has utilized lunar penetrating radar (LPR), which is equipped on the lunar rover named as Yutu, to detect the lunar geological structure in Northern Imbrium (44.1260N, 19.5014W) for the first time. As an in situ detector, Chang'E-3 LPR has relative higher horizontal and vertical resolution and less clutter impact compared to spaceborne radars and earth-based radars. In this work, we analyze the LPR data at 500 MHz transmission frequency to obtain the shallow subsurface structure of the landing area of Chang'E-3 in Mare Imbrium. Filter method and amplitude recovery algorithms are utilized to alleviate the adverse effects of environment and system noises and compensate the amplitude losses during signal propagation. Based on the processed radar image, we observe numerous diffraction hyperbolae, which may be caused by discrete reflectors beneath the lunar surface. Hyperbolae fitting method is utilized to reverse the average dielectric constant to certain depth (ε bar). Overall, the estimated ε bar increases with the depth and ε bar could be classified into three categories. Average ε bar of each category is 2.47, 3.40 and 6.16, respectively. Because of the large gap between the values of ε bar of neighboring categories, we speculate a three-layered structure of the shallow surface of LPR exploration region. One possible geological picture of the speculated three-layered structure is presented as follows. The top layer is weathered layer of ejecta blanket with its average thickness and bound on error is 0.95±0.02 m. The second layer is the ejecta blanket of the nearby impact crater, and the corresponding average thickness is about 2.30±0.07 m, which is in good agreement with the two primary models of ejecta blanket thickness as a function of distance from the crater center. The third layer is regarded as a mixture of stones and soil. The echoes below the third layer are in the same magnitude as the noises, which may indicate that the fourth layer, if it exists, is uniform (no clear reflector) and its thickness is beyond the detection limit of LPR. Hence, we infer the fourth layer is a basalt layer.

A composite numerical model for assessing subsurface transport of oily wastes and chemical constituents

NASA Astrophysics Data System (ADS)

Panday, S.; Wu, Y. S.; Huyakorn, P. S.; Wade, S. C.; Saleem, Z. A.

1997-02-01

Subsurface fate and transport models are utilized to predict concentrations of chemicals leaching from wastes into downgradient receptor wells. The contaminant concentrations in groundwater provide a measure of the risk to human health and the environment. The level of potential risk is currently used by the U.S. Environmental Protection Agency to determine whether management of the wastes should conform to hazardous waste management standards. It is important that the transport and fate of contaminants is simulated realistically. Most models in common use are inappropriate for simulating the migration of wastes containing significant fractions of nonaqueous-phase liquids (NAPLs). The migration of NAPL and its dissolved constituents may not be reliably predicted using conventional aqueous-phase transport simulations. To overcome this deficiency, an efficient and robust regulatory assessment model incorporating multiphase flow and transport in the unsaturated and saturated zones of the subsurface environment has been developed. The proposed composite model takes into account all of the major transport processes including infiltration and ambient flow of NAPL, entrapment of residual NAPL, adsorption, volatilization, degradation, dissolution of chemical constituents, and transport by advection and hydrodynamic dispersion. Conceptually, the subsurface is treated as a composite unsaturated zone-saturated zone system. The composite simulator consists of three major interconnected computational modules representing the following components of the migration pathway: (1) vertical multiphase flow and transport in the unsaturated zone; (2) areal movement of the free-product lens in the saturated zone with vertical equilibrium; and (3) three-dimensional aqueous-phase transport of dissolved chemicals in ambient groundwater. Such a composite model configuration promotes computational efficiency and robustness (desirable for regulatory assessment applications). Two examples are presented to demonstrate the model verification and a site application. Simulation results obtained using the composite modeling approach are compared with a rigorous numerical solution and field observations of crude oil saturations and plume concentrations of total dissolved organic carbon at a spill site in Minnesota, U.S.A. These comparisons demonstrate the ability of the present model to provide realistic depiction of field-scale situations.

Using Analog Field Tests To Link and Prepare Science and In-Situ Resource Utilization for Future Space Missions

NASA Technical Reports Server (NTRS)

Sanders, Gerald B.

2010-01-01

A major goal of NASA s human exploration program is to learn how to use the resources of space, known as In-Situ Resource Utilization (ISRU), to lower the cost and risk of human space exploration. Successful implementation of ISRU requires detailed knowledge of surface and subsurface materials, minerals, and volatiles that may be present. This same information is required to better understand the physical and geologic composition, structure, origin, and evolution of the Moon, Mars, and other extraterrestrial bodies of interest. It is also important to recognize that while ISRU and science objectives may be similar, the desired method or hardware to achieve the information desired may be drastically different. One method to promote understanding, coordination, and joint development of instruments and operations between Science and ISRU is the use of analog field demonstrations.

Cultivating the Deep Subsurface Microbiome

NASA Astrophysics Data System (ADS)

Casar, C. P.; Osburn, M. R.; Flynn, T. M.; Masterson, A.; Kruger, B.

2017-12-01

Subterranean ecosystems are poorly understood because many microbes detected in metagenomic surveys are only distantly related to characterized isolates. Cultivating microorganisms from the deep subsurface is challenging due to its inaccessibility and potential for contamination. The Deep Mine Microbial Observatory (DeMMO) in Lead, SD however, offers access to deep microbial life via pristine fracture fluids in bedrock to a depth of 1478 m. The metabolic landscape of DeMMO was previously characterized via thermodynamic modeling coupled with genomic data, illustrating the potential for microbial inhabitants of DeMMO to utilize mineral substrates as energy sources. Here, we employ field and lab based cultivation approaches with pure minerals to link phylogeny to metabolism at DeMMO. Fracture fluids were directed through reactors filled with Fe3O4, Fe2O3, FeS2, MnO2, and FeCO3 at two sites (610 m and 1478 m) for 2 months prior to harvesting for subsequent analyses. We examined mineralogical, geochemical, and microbiological composition of the reactors via DNA sequencing, microscopy, lipid biomarker characterization, and bulk C and N isotope ratios to determine the influence of mineralogy on biofilm community development. Pre-characterized mineral chips were imaged via SEM to assay microbial growth; preliminary results suggest MnO2, Fe3O4, and Fe2O3 were most conducive to colonization. Solid materials from reactors were used as inoculum for batch cultivation experiments. Media designed to mimic fracture fluid chemistry was supplemented with mineral substrates targeting metal reducers. DNA sequences and microscopy of iron oxide-rich biofilms and fracture fluids suggest iron oxidation is a major energy source at redox transition zones where anaerobic fluids meet more oxidizing conditions. We utilized these biofilms and fluids as inoculum in gradient cultivation experiments targeting microaerophilic iron oxidizers. Cultivation of microbes endemic to DeMMO, a system locally dominated by unclassified and candidate phyla, has the potential to yield novel subsurface organisms with unique physiologies. We intend to further utilize subsurface isolates to probe the effects of geochemical perturbations on biosignatures in future studies, thus broadening our understanding of subterranean ecosystems.

Search for life on Mars.

PubMed

Brack, A; Clancy, P; Fitton, B; Hoffmann, B; Horneck, G; Kurat, G; Maxwell, J; Ori, G; Pillinger, C; Raulin, F; Thomas, N; Westall, F

1998-06-01

A multi-user integrated suite of instruments designed to optimize the search for evidence of life on Mars is described. The package includes: -Surface inspection and surface environment analysis to identify the potential Mars landing sites, to inspect the surface geology and mineralogy, to search for visible surficial microbial macrofossils, to study the surface radiation budget and surface oxidation processes, to search for niches for extant life. -Subsurface sample acquisition by core drilling -Analysis of surface and subsurface minerals and organics to characterize the surface mineralogy, to analyse the surface and subsurface oxidants, to analyse the mineralogy of subsurface aliquots, to analyse the organics present in the subsurface aliquots (elemental and molecular composition, isotopes, chirality). -Macroscopic and microscopic inspection of subsurface aliquots to search for life's indicators (paleontological, biological, mineralogical) and to characterize the mineralogy of the subsurface aliquots. The study is led by ESA Manned Spaceflight and Microgravity Directorate.

Surface and subsurface geologic risk factors to ground water affecting brownfield redevelopment potential.

PubMed

Kaufman, Martin M; Murray, Kent S; Rogers, Daniel T

2003-01-01

A model is created for assessing the redevelopment potential of brownfields. The model is derived from a space and time conceptual framework that identifies and measures the surface and subsurface risk factors present at brownfield sites. The model then combines these factors with a contamination extent multiplier at each site to create an index of redevelopment potential. Results from the application of the model within an urbanized watershed demonstrate clear differences between the redevelopment potential present within five different near-surface geologic units, with those units containing clay being less vulnerable to subsurface contamination. With and without the extent multiplier, the total risk present at the brownfield sites within all the geologic units is also strongly correlated to the actual costs of remediation. Thus, computing the total surface and subsurface risk within a watershed can help guide the remediation efforts at broad geographic scales, and prioritize the locations for redevelopment.

Method and Apparatus for Computed Imaging Backscatter Radiography

NASA Technical Reports Server (NTRS)

Shedlock, Daniel (Inventor); Sabri, Nissia (Inventor); Dugan, Edward T. (Inventor); Jacobs, Alan M. (Inventor); Meng, Christopher (Inventor)

2013-01-01

Systems and methods of x-ray backscatter radiography are provided. A single-sided, non-destructive imaging technique utilizing x-ray radiation to image subsurface features is disclosed, capable of scanning a region using a fan beam aperture and gathering data using rotational motion.

MINERALOGICAL PRESERVATION OF SOLID SAMPLES COLLECTED FROM ANOXIC SUBSURFACE ENVIRONMENTS

EPA Science Inventory

Remedial technologies utilized at hazardous waste sites for the treatment of metal and metalloid contaminants often take advantage of reduction-oxidation (redox) processes to reach ground water clean up goals. This is because redox reactions, in many cases, govern the biogeochem...

Terahertz imaging for subsurface investigation of art paintings

NASA Astrophysics Data System (ADS)

Locquet, A.; Dong, J.; Melis, M.; Citrin, D. S.

2017-08-01

Terahertz (THz) reflective imaging is applied to the stratigraphic and subsurface investigation of oil paintings, with a focus on the mid-20th century Italian painting, `After Fishing', by Ausonio Tanda. THz frequency-wavelet domain deconvolution, which is an enhanced deconvolution technique combining frequency-domain filtering and stationary wavelet shrinkage, is utilized to resolve the optically thin paint layers or brush strokes. Based on the deconvolved terahertz data, the stratigraphy of the painting including the paint layers is reconstructed and subsurface features are clearly revealed. Specifically, THz C-scans and B-scans are analyzed based on different types of deconvolved signals to investigate the subsurface features of the painting, including the identification of regions with more than one paint layer, the refractive-index difference between paint layers, and the distribution of the paint-layer thickness. In addition, THz images are compared with X-ray images. The THz image of the thickness distribution of the paint exhibits a high degree of correlation with the X-ray transmission image, but THz images also reveal defects in the paperboard that cannot be identified in the X-ray image. Therefore, our results demonstrate that THz imaging can be considered as an effective tool for the stratigraphic and subsurface investigation of art paintings. They also open up the way for the use of non-ionizing THz imaging as a potential substitute for ionizing X-ray analysis in nondestructive evaluation of art paintings.

Uranium Biomineralization by Natural Microbial Phosphatase Activities in the Subsurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sobecky, Patricia A.

2015-04-06

In this project, inter-disciplinary research activities were conducted in collaboration among investigators at The University of Alabama (UA), Georgia Institute of Technology (GT), Lawrence Berkeley National Laboratory (LBNL), Brookhaven National Laboratory (BNL), the DOE Joint Genome Institute (JGI), and the Stanford Synchrotron Radiation Light source (SSRL) to: (i) confirm that phosphatase activities of subsurface bacteria in Area 2 and 3 from the Oak Ridge Field Research Center result in solid U-phosphate precipitation in aerobic and anaerobic conditions; (ii) investigate the eventual competition between uranium biomineralization via U-phosphate precipitation and uranium bioreduction; (iii) determine subsurface microbial community structure changes of Areamore » 2 soils following organophosphate amendments; (iv) obtain the complete genome sequences of the Rahnella sp. Y9-602 and the type-strain Rahnella aquatilis ATCC 33071 isolated from these soils; (v) determine if polyphosphate accumulation and phytate hydrolysis can be used to promote U(VI) biomineralization in subsurface sediments; (vi) characterize the effect of uranium on phytate hydrolysis by a new microorganism isolated from uranium-contaminated sediments; (vii) utilize positron-emission tomography to label and track metabolically-active bacteria in soil columns, and (viii) study the stability of the uranium phosphate mineral product. Microarray analyses and mineral precipitation characterizations were conducted in collaboration with DOE SBR-funded investigators at LBNL. Thus, microbial phosphorus metabolism has been shown to have a contributing role to uranium immobilization in the subsurface.« less

The Mojave Subsurface Bio-Geochemistry Explorer (MOSBE)

NASA Technical Reports Server (NTRS)

Guerrero, J.; Beegle, L.; Abbey, W.; Bhartia, R.; Kounaves, S.; Russell, M.; Towles, D.

2012-01-01

The MOSBE Team has developed a terrestrial field campaign to explore two subsurface biological habitats under the Mojave Desert. This field campaign will not only help us understand terrestrial desert biology, but also will develop methodologies and strategies for potential future Mars missions that would seek to explore the Martian subsurface. We have proposed to the ASTEP program to integrate a suite of field demonstrated instruments with a 20 m subsurface drill as a coherent unit, the Mojave Subsurface Bio-geochemistry Explorer. The ATK Space Modular Planetary Drill System (MPDS) requires no drilling fluid, which allows aseptic sampling, can penetrate lithic ground up to 20 meters of depth, and utilizes less than 100 Watts throughout the entire depth. The drill has been developed and demonstrated in field testing to a depth of 10 meters in Arizona, December 2002. In addition to caching a continuous core throughout the drilling depth, it also generates and caches cuttings and fines that are strata-graphically correlated with the core. As a core segment is brought to the surface, it will be analyzed for texture and structure by a color microscopic imager and for relevant chemistry and mineralogy with a UV fluorescence/Raman spectrometer. Organic and soluble ionic species will be identified through two instruments -- a microcapillary electrophoresis, and an ion trap mass spectrometer that have been developed under PIDDP, ASTID and MIDP funding.

Prairie Pothole Region wetlands and subsurface drainage systems: Key factors for determining drainage setback distances

USGS Publications Warehouse

Tangen, Brian; Wiltermuth, Mark T.

2018-01-01

Use of agricultural subsurface drainage systems in the Prairie Pothole Region of North America continues to increase, prompting concerns over potential negative effects to the Region's vital wetlands. The U.S. Fish and Wildlife Service protects a large number of wetlands through conservation easements that often utilize standard lateral setback distances to provide buffers between wetlands and drainage systems. Because of a lack of information pertaining to the efficacy of these setback distances for protecting wetlands, information is required to support the decision making for placement of subsurface drainage systems adjacent to wetlands. We used qualitative graphical analyses and data comparisons to identify characteristics of subsurface drainage systems and wetland catchments that could be considered when assessing setback distances. We also compared setback distances with catchment slope lengths to determine if they typically exclude drainage systems from the catchment. We demonstrated that depth of a subsurface drainage system is a key factor for determining drainage setback distances. Drainage systems located closer to the surface (shallow) typically could be associated with shorter lateral setback distances compared with deeper systems. Subsurface drainage systems would be allowed within a wetland's catchment for 44–59% of catchments associated with wetland conservation easements in North Dakota. More specifically, results suggest that drainage setback distances generally would exclude drainage systems from catchments of the smaller wetlands that typically have shorter slopes in the adjacent upland contributing area. For larger wetlands, however, considerable areas of the catchment would be vulnerable to drainage that may affect wetland hydrology. U.S. Fish and Wildlife Service easements are associated with > 2,000 km2 of wetlands in North Dakota, demonstrating great potential to protect these systems from drainage depending on policies for installing subsurface drainage systems on these lands. The length of slope of individual catchments and depth of subsurface drainage systems could be considered when prescribing drainage setback distances and assessing potential effects to wetland hydrology. Moreover, because of uncertainties associated with the efficacy of standard drainage setback distances, exclusion of subsurface drainage systems from wetland catchments would be ideal when the goal is to protect wetlands.

Enhanced groundwater recharge rates and altered recharge sensitivity to climate variability through subsurface heterogeneity

PubMed Central

Hartmann, Andreas; Gleeson, Tom; Wagener, Thorsten

2017-01-01

Our environment is heterogeneous. In hydrological sciences, the heterogeneity of subsurface properties, such as hydraulic conductivities or porosities, exerts an important control on water balance. This notably includes groundwater recharge, which is an important variable for efficient and sustainable groundwater resources management. Current large-scale hydrological models do not adequately consider this subsurface heterogeneity. Here we show that regions with strong subsurface heterogeneity have enhanced present and future recharge rates due to a different sensitivity of recharge to climate variability compared with regions with homogeneous subsurface properties. Our study domain comprises the carbonate rock regions of Europe, Northern Africa, and the Middle East, which cover ∼25% of the total land area. We compare the simulations of two large-scale hydrological models, one of them accounting for subsurface heterogeneity. Carbonate rock regions strongly exhibit “karstification,” which is known to produce particularly strong subsurface heterogeneity. Aquifers from these regions contribute up to half of the drinking water supply for some European countries. Our results suggest that water management for these regions cannot rely on most of the presently available projections of groundwater recharge because spatially variable storages and spatial concentration of recharge result in actual recharge rates that are up to four times larger for present conditions and changes up to five times larger for potential future conditions than previously estimated. These differences in recharge rates for strongly heterogeneous regions suggest a need for groundwater management strategies that are adapted to the fast transit of water from the surface to the aquifers. PMID:28242703

Enhanced Groundwater Recharge Rates and Altered Recharge Sensitivity to Climate Variability Through Subsurface Heterogeneity

NASA Technical Reports Server (NTRS)

Hartmann, Andreas; Gleeson, Tom; Wada, Yoshihide; Wagener, Thorsten

2017-01-01

Our environment is heterogeneous. In hydrological sciences, the heterogeneity of subsurface properties, such as hydraulic conductivities or porosities, exerts an important control on water balance. This notably includes groundwater recharge, which is an important variable for efficient and sustainable groundwater resources management. Current large-scale hydrological models do not adequately consider this subsurface heterogeneity. Here we show that regions with strong subsurface heterogeneity have enhanced present and future recharge rates due to a different sensitivity of recharge to climate variability compared with regions with homogeneous subsurface properties. Our study domain comprises the carbonate rock regions of Europe, Northern Africa, and the Middle East, which cover 25 of the total land area. We compare the simulations of two large-scale hydrological models, one of them accounting for subsurface heterogeneity. Carbonate rock regions strongly exhibit karstification, which is known to produce particularly strong subsurface heterogeneity. Aquifers from these regions contribute up to half of the drinking water supply for some European countries. Our results suggest that water management for these regions cannot rely on most of the presently available projections of groundwater recharge because spatially variable storages and spatial concentration of recharge result in actual recharge rates that are up to four times larger for present conditions and changes up to five times larger for potential future conditions than previously estimated. These differences in recharge rates for strongly heterogeneous regions suggest a need for groundwater management strategies that are adapted to the fast transit of water from the surface to the aquifers.

Ecology, physiology, and phylogeny of deep subsurface Sphingomonas sp.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fredrickson, Jim K.; Balkwill, David L.; Romine, Margaret F.

Several new species of the genus Sphingomonas including S. aromaticivorans, S. stygia, and S. subterranea that have the capacity for degrading a broad range of aromatic compounds including toluene, naphthalene, xylenes, p-cresol, fluorene, biphenyl, and dibenzothiophene, were isolated from deeply-buried (>200 m) sediments of the US Atlantic coastal plain (ACP). In S. aromaticivorans F199, many of the genes involved in the catabolism of these aromatic compounds are encoded on a 184-kb conjugative plasmid; some of the genes involved in aromatic catabolism are plasmid-encoded in the other strains as well. Members of the genus Sphingomonas were common among aerobic heterotrophic bacteriamore » cultured from ACP sediments and have been detected in deep subsurface environments elsewhere. The major source of organic carbon for heterotrophic metabolism in ACP deep aquifers is lignite that originated from plant material buried with the sediments. We speculate that the ability of the subsurface Sphingomonas strains to degrade a wide array of aromatic compounds represents an adaptation for utilization of sedimentary lignite. These and related subsurface Sphingomonas spp may play an important role in the transformation of sedimentary organic carbon in the aerobic and microaerobic regions of the deep aquifers of the ACP.« less

Ecology, physiology, and phylogeny of deep subsurface Sphingomonas sp.

PubMed

Fredrickson, J K; Balkwill, D L; Romine, M F; Shi, T

1999-10-01

Several new species of the genus Sphingomonas including S. aromaticivorans, S. stygia, and S. subterranea that have the capacity for degrading a broad range of aromatic compounds including toluene, naphthalene, xylenes, p-cresol, fluorene, biphenyl, and dibenzothiophene, were isolated from deeply-buried (>200 m) sediments of the US Atlantic coastal plain (ACP). In S. aromaticivorans F199, many of the genes involved in the catabolism of these aromatic compounds are encoded on a 184-kb conjugative plasmid; some of the genes involved in aromatic catabolism are plasmid-encoded in the other strains as well. Members of the genus Sphingomonas were common among aerobic heterotrophic bacteria cultured from ACP sediments and have been detected in deep subsurface environments elsewhere. The major source of organic carbon for heterotrophic metabolism in ACP deep aquifers is lignite that originated from plant material buried with the sediments. We speculate that the ability of the subsurface Sphingomonas strains to degrade a wide array of aromatic compounds represents an adaptation for utilization of sedimentary lignite. These and related subsurface Sphingomonas spp may play an important role in the transformation of sedimentary organic carbon in the aerobic and microaerobic regions of the deep aquifers of the ACP.

Methods and system for subsurface stabilization using jet grouting

DOEpatents

Loomis, Guy G.; Weidner, Jerry R.; Farnsworth, Richard K.; Gardner, Bradley M.; Jessmore, James J.

1999-01-01

Methods and systems are provided for stabilizing a subsurface area such as a buried waste pit for either long term storage, or interim storage and retrieval. A plurality of holes are drilled into the subsurface area with a high pressure drilling system provided with a drill stem having jet grouting nozzles. A grouting material is injected at high pressure through the jet grouting nozzles into a formed hole while the drill stem is withdrawn from the hole at a predetermined rate of rotation and translation. A grout-filled column is thereby formed with minimal grout returns, which when overlapped with other adjacent grout-filled columns encapsulates and binds the entire waste pit area to form a subsurface agglomeration or monolith of grout, soil, and waste. The formed monolith stabilizes the buried waste site against subsidence while simultaneously providing a barrier against contaminate migration. The stabilized monolith can be left permanently in place or can be retrieved if desired by using appropriate excavation equipment. The jet grouting technique can also be utilized in a pretreatment approach prior to in situ vitrification of a buried waste site. The waste encapsulation methods and systems are applicable to buried waste materials such as mixed waste, hazardous waste, or radioactive waste.

Dynamics of the Genetic Diversity of Subsurface Microbial Communities and Their Applications to Contaminated Site Cleanups

EPA Science Inventory

When compared to traditional approaches, the utilization of molecular and genomic techniques to soil and groundwater cleanup investigations can reduce inherent parameter variability when conducting bench and pilot-scale investigations or carrying out full-scale field applications...

A Review of distribution and quantity of lingering subsurface oil from the Exxon Valdez Oil Spill

NASA Astrophysics Data System (ADS)

Nixon, Zachary; Michel, Jacqueline

2018-01-01

Remaining lingering subsurface oil residues from the Exxon Valdez oil spill (EVOS) are, at present, patchily distributed across the geologically complex and spatially extensive shorelines of Prince William Sound and the Gulf of Alaska. We review and synthesize previous literature describing the causal geomorphic and physical mechanisms for persistence of oil in the intertidal subsurface sediments of these areas. We also summarize previous sampling and modeling efforts, and refine previously presented models with additional data to characterize the present-day linear and areal spatial extent, and quantity of lingering subsurface oil. In the weeks after the spill in March of 1989, approximately 17,750 t of oil were stranded along impacted shorelines, and by October of 1992, only 2% of the mass of spilled oil was estimated to remain in intertidal areas. We estimate that lingering subsurface residues, generally between 5 and 20 cm thick and sequestered below 10-20 cm of clean sediment, are present over 30 ha of intertidal area, along 11.4 km of shoreline, and represent approximately 227 t or 0.6% of the total mass of spilled oil. These residues are typically located in finer-grained sand and gravel sediments, often under an armor of cobble- or boulder-sized clasts, in areas with limited groundwater flow and porosity. Persistence of these residues is correlated with heavy initial oil loading together with localized sheltering from physical disturbance such as wave energy within the beach face. While no longer generally bioavailable and increasingly chemically weathered, present removal rates for these remaining subsurface oil residues have slowed to nearly zero. The only remaining plausible removal mechanisms will operate over time scales of decades.

Subsurface defects of fused silica optics and laser induced damage at 351 nm.

PubMed

Hongjie, Liu; Jin, Huang; Fengrui, Wang; Xinda, Zhou; Xin, Ye; Xiaoyan, Zhou; Laixi, Sun; Xiaodong, Jiang; Zhan, Sui; Wanguo, Zheng

2013-05-20

Many kinds of subsurface defects are always present together in the subsurface of fused silica optics. It is imperfect that only one kind of defects is isolated to investigate its impact on laser damage. Therefore it is necessary to investigate the impact of subsurface defects on laser induced damage of fused silica optics with a comprehensive vision. In this work, we choose the fused silica samples manufactured by different vendors to characterize subsurface defects and measure laser induced damage. Contamination defects, subsurface damage (SSD), optical-thermal absorption and hardness of fused silica surface are characterized with time-of-flight secondary ion mass spectrometry (TOF-SIMS), fluorescence microscopy, photo-thermal common-path interferometer and fully automatic micro-hardness tester respectively. Laser induced damage threshold and damage density are measured by 351 nm nanosecond pulse laser. The correlations existing between defects and laser induced damage are analyzed. The results show that Cerium element and SSD both have a good correlation with laser-induced damage thresholds and damage density. Research results evaluate process technology of fused silica optics in China at present. Furthermore, the results can provide technique support for improving laser induced damage performance of fused silica.

Appendix to theory of radio-frequency interferometry in geophysical subsurface probing, numerical results

NASA Technical Reports Server (NTRS)

Kong, J. A.; Tsang, L.

1974-01-01

A series of interference and radiation patterns are presented for radio interferometry in subsurface probing. The interference patterns are due both to a vertical magnetic dipole and to a horizontal electric dipole. Mode solutions are also presented for layer thickness equal to 1 wavelength, as well as for thin layers.

[Correlation of substrate structure and hydraulic characteristics in subsurface flow constructed wetlands].

PubMed

Bai, Shao-Yuan; Song, Zhi-Xin; Ding, Yan-Li; You, Shao-Hong; He, Shan

2014-02-01

The correlation of substrate structure and hydraulic characteristics was studied by numerical simulation combined with experimental method. The numerical simulation results showed that the permeability coefficient of matrix had a great influence on hydraulic efficiency in subsurface flow constructed wetlands. The filler with a high permeability coefficient had a worse flow field distribution in the constructed wetland with single layer structure. The layered substrate structure with the filler permeability coefficient increased from surface to bottom could avoid the short-circuited flow and dead-zones, and thus, increased the hydraulic efficiency. Two parallel pilot-scale constructed wetlands were built according to the numerical simulation results, and tracer experiments were conducted to validate the simulation results. The tracer experiment result showed that hydraulic characteristics in the layered constructed wetland were obviously better than that in the single layer system, and the substrate effective utilization rates were 0.87 and 0.49, respectively. It was appeared that numerical simulation would be favorable for substrate structure optimization in subsurface flow constructed wetlands.

Characterization on White Etching Layer Formed During Ceramic Milling of Inconel 718

NASA Astrophysics Data System (ADS)

Kruk, A.; Wusatowska-Sarnek, A. M.; Ziętara, M.; Jemielniak, K.; Siemiątkowski, Z.; Czyrska-Filemonowicz, A.

2018-03-01

A comprehensive characterization of the near surface formed during the interrupted high-speed dry ceramic milling of IN718 was performed using light imaging, SEM/EDX, TEM and nano-hardness methods. It was found out that even an initial cut by a fresh tool creates a sub-surface alteration roughly 20 µm deep. The depth of altered sub-surface progressively changed to a roughly 40 µm when the tool reached an approximately half of its life, and almost 60 µm at the tool's end of the life. In the last two cases, the visible WEL (utilizing a light microscope) of the thickness roughly 6 and 15 µm was created, respectively. The outermost layer of the deformed subsurface was found to be for all three cases approximately 1.5 µm thick and composed of dynamically recrystallized γ phase grains with the average diameter of approximately 150 nm. This layer was free of δ phase and γ' or γ″ precipitates. It was followed by a plastically deformed zone.

Novel determination of radon-222 velocity in deep subsurface rocks and the feasibility to using radon as an earthquake precursor

NASA Astrophysics Data System (ADS)

Zafrir, Hovav; Ben Horin, Yochai; Malik, Uri; Chemo, Chaim; Zalevsky, Zeev

2016-09-01

A novel technique utilizing simultaneous radon monitoring by gamma and alpha detectors to differentiate between the radon climatic driving forces and others has been improved and used for deep subsurface investigation. Detailed long-term monitoring served as a proxy for studying radon movement within the shallow and deep subsurface, as well as for analyzing the effect of various parameters of the radon transport pattern. The main achievements of the investigation are (a) determination, for the first time, of the radon movement velocity within rock layers at depths of several tens of meters, namely, 25 m/h on average; (b) distinguishing between the diurnal periodical effect of the ambient temperature and the semidiurnal effect of the ambient pressure on the radon temporal spectrum; and (c) identification of a radon random preseismic anomaly preceding the Nuweiba, M 5.5 earthquake of 27 June 2015 that occurred within Dead Sea Fault Zone.

Method and apparatus for subsurface exploration

NASA Technical Reports Server (NTRS)

Wilcox, Brian (Inventor)

2002-01-01

A subsurface explorer (SSX) for exploring beneath the terrestrial surface of planetary bodies such as the Earth, Mars, or comets. This exploration activity utilizes appropriate sensors and instrument to evaluate the composition, structure, mineralogy and possibly biology of the subsurface medium, as well as perhaps the ability to return samples of that medium back to the surface. The vehicle comprises an elongated skin or body having a front end and a rear end, with a nose piece at the front end for imparting force to composition material of the planetary body. Force is provided by a hammer mechanism to the back side of a nose piece from within the body of the vehicle. In the preferred embodiment, a motor spins an intermediate shaft having two non-uniform threads along with a hammer which engages these threads with two conical rollers. A brake assembly halts the rotation of the intermediate shaft, causing the conical roller to spin down the non-uniform thread to rapidly and efficiently convert the rotational kinetic energy of the hammer into translational energy.

A reference data set of hillslope rainfall-runoff response, Panola Mountain Research Watershed, United States

USGS Publications Warehouse

Tromp-van, Meerveld; James, A.L.; McDonnell, Jeffery J.; Peters, N.E.

2008-01-01

Although many hillslope hydrologic investigations have been conducted in different climate, topographic, and geologic settings, subsurface stormflow remains a poorly characterized runoff process. Few, if any, of the existing data sets from these hillslope investigations are available for use by the scientific community for model development and validation or conceptualization of subsurface stormflow. We present a high-resolution spatial and temporal rainfall-runoff data set generated from the Panola Mountain Research Watershed trenched experimental hillslope. The data set includes surface and subsurface (bedrock surface) topographic information and time series of lateral subsurface flow at the trench, rainfall, and subsurface moisture content (distributed soil moisture content and groundwater levels) from January to June 2002. Copyright 2008 by the American Geophysical Union.

Active microbial biofilms in deep poor porous continental subsurface rocks.

PubMed

Escudero, Cristina; Vera, Mario; Oggerin, Monike; Amils, Ricardo

2018-01-24

Deep continental subsurface is defined as oligotrophic environments where microorganisms present a very low metabolic rate. To date, due to the energetic cost of production and maintenance of biofilms, their existence has not been considered in poor porous subsurface rocks. We applied fluorescence in situ hybridization techniques and confocal laser scanning microscopy in samples from a continental deep drilling project to analyze the prokaryotic diversity and distribution and the possible existence of biofilms. Our results show the existence of natural microbial biofilms at all checked depths of the Iberian Pyrite Belt (IPB) subsurface and the co-occurrence of bacteria and archaea in this environment. This observation suggests that multi-species biofilms may be a common and widespread lifestyle in subsurface environments.

Analysis

NASA Astrophysics Data System (ADS)

Abdelazeem, Maha; El-Sawy, El-Sawy K.; Gobashy, Mohamed M.

2013-06-01

Ar Rika fault zone constitutes one of the two major parts of the NW-SE Najd fault system (NFS), which is one of the most prominent structural features located in the east of the center of the Arabian Shield, Saudi Arabia. By using Enhancement Thematic Mapper data (ETM+) and Principle Component Analysis (PCA), surface geological characteristics, distribution of rock types, and the different trends of linear features and faults are determined in the study area. First and second order magnetic gradients of the geomagnetic field at the North East of Wadi Ar Rika have been calculated in the frequency domain to map both surface and subsurface lineaments and faults. Lineaments as deduced from previous studies, suggest an extension of the NFS beneath the cover rocks in the study area. In the present study, integration of magnetic gradients and remote sensing analysis that resulted in different valuable derivative maps confirm the subsurface extension of some of the surface features. The 3D Euler deconvolution, the total gradient, and the tilt angle maps have been utilized to determine accurately the distribution of shear zones, the tectonic implications, and the internal structures of the terranes in the Ar Rika quadrangle in three dimensions.

Integrating real-time subsurface hydrologic monitoring with empirical rainfall thresholds to improve landslide early warning

USGS Publications Warehouse

Mirus, Benjamin B.; Becker, Rachel E.; Baum, Rex L.; Smith, Joel B.

2018-01-01

Early warning for rainfall-induced shallow landsliding can help reduce fatalities and economic losses. Although these commonly occurring landslides are typically triggered by subsurface hydrological processes, most early warning criteria rely exclusively on empirical rainfall thresholds and other indirect proxies for subsurface wetness. We explore the utility of explicitly accounting for antecedent wetness by integrating real-time subsurface hydrologic measurements into landslide early warning criteria. Our efforts build on previous progress with rainfall thresholds, monitoring, and numerical modeling along the landslide-prone railway corridor between Everett and Seattle, Washington, USA. We propose a modification to a previously established recent versus antecedent (RA) cumulative rainfall thresholds by replacing the antecedent 15-day rainfall component with an average saturation observed over the same timeframe. We calculate this antecedent saturation with real-time telemetered measurements from five volumetric water content probes installed in the shallow subsurface within a steep vegetated hillslope. Our hybrid rainfall versus saturation (RS) threshold still relies on the same recent 3-day rainfall component as the existing RA thresholds, to facilitate ready integration with quantitative precipitation forecasts. During the 2015–2017 monitoring period, this RS hybrid approach has an increase of true positives and a decrease of false positives and false negatives relative to the previous RA rainfall-only thresholds. We also demonstrate that alternative hybrid threshold formats could be even more accurate, which suggests that further development and testing during future landslide seasons is needed. The positive results confirm that accounting for antecedent wetness conditions with direct subsurface hydrologic measurements can improve thresholds for alert systems and early warning of rainfall-induced shallow landsliding.

Subsurface earthworm casts can be important soil microsites specifically influencing the growth of grassland plants.

PubMed

Zaller, Johann G; Wechselberger, Katharina F; Gorfer, Markus; Hann, Patrick; Frank, Thomas; Wanek, Wolfgang; Drapela, Thomas

Earthworms (Annelida: Oligochaeta) deposit several tons per hectare of casts enriched in nutrients and/or arbuscular mycorrhizal fungi (AMF) and create a spatial and temporal soil heterogeneity that can play a role in structuring plant communities. However, while we begin to understand the role of surface casts, it is still unclear to what extent plants utilize subsurface casts. We conducted a greenhouse experiment using large mesocosms (volume 45 l) to test whether (1) soil microsites consisting of earthworm casts with or without AMF (four Glomus taxa) affect the biomass production of 11 grassland plant species comprising the three functional groups grasses, forbs, and legumes, (2) different ecological groups of earthworms (soil dwellers- Aporrectodea caliginosa vs. vertical burrowers- Lumbricus terrestris ) alter potential influences of soil microsites (i.e., four earthworms × two subsurface microsites × two AMF treatments). Soil microsites were artificially inserted in a 25-cm depth, and afterwards, plant species were sown in a regular pattern; the experiment ran for 6 months. Our results show that minute amounts of subsurface casts (0.89 g kg -1 soil) decreased the shoot and root production of forbs and legumes, but not that of grasses. The presence of earthworms reduced root biomass of grasses only. Our data also suggest that subsurface casts provide microsites from which root AMF colonization can start. Ecological groups of earthworms did not differ in their effects on plant production or AMF distribution. Taken together, these findings suggest that subsurface earthworm casts might play a role in structuring plant communities by specifically affecting the growth of certain functional groups of plants.

Export of nutrients and major ionic solutes from a rain forest catchment in the Central Amazon Basin

NASA Astrophysics Data System (ADS)

Lesack, Lance F. W.

1993-03-01

The relative roles of base flow runoff versus storm flow runoff versus subsurface outflow in controlling total export of solutes from a 23.4-ha catchment of undisturbed rain forest in the central Amazon Basin were evaluated from water and solute flux measurements performed over a 1 year period. Solutes exported via 173 storms during the study were estimated from stream water samples collected during base flow conditions and during eight storms, and by utilizing a hydrograph separation technique in combination with a mixing model to partition storm flow from base flow fluxes. Solutes exported by subsurface outflow were estimated from groundwater samples from three nests of piezometers installed into the streambed, and concurrent measurements of hydraulic conductivity and hydraulic head gradients. Base flow discharge represented 92% of water outflow from the basin and was the dominant pathway of solute export. Although storm flow discharge represented only 5% of total water outflow, storm flow solute fluxes represented up to 25% of the total annual export flux, though for many solutes the portion was less. Subsurface outflow represented only 2.5% of total water outflow, and subsurface solute fluxes never represented more than 5% of the total annual export flux. Measurement errors were relatively high for storm flow and subsurface outflow fluxes, but cumulative measurement errors associated with the total solute fluxes exported from the catchment, in most cases, ranged from only ±7% to 14% because base flow fluxes were measured relatively well. The export fluxes of most solutes are substantially less than previously reported for comparable small catchments in the Amazon basin, and these differences cannot be reconciled by the fact that storm flow and subsurface outflows were not appropriately measured in previous studies.

Using noble gases to investigate mountain-front recharge

USGS Publications Warehouse

Manning, A.H.; Solomon, D.K.

2003-01-01

Mountain-front recharge is a major component of recharge to inter-mountain basin-fill aquifers. The two components of mountain-front recharge are (1) subsurface inflow from the mountain block (subsurface inflow), and (2) infiltration from perennial and ephemeral streams near the mountain front (stream seepage). The magnitude of subsurface inflow is of central importance in source protection planning for basin-fill aquifers and in some water rights disputes, yet existing estimates carry large uncertainties. Stable isotope ratios can indicate the magnitude of mountain-front recharge relative to other components, but are generally incapable of distinguishing subsurface inflow from stream seepage. Noble gases provide an effective tool for determining the relative significance of subsurface inflow, specifically. Dissolved noble gas concentrations allow for the determination of recharge temperature, which is correlated with recharge elevation. The nature of this correlation cannot be assumed, however, and must be derived for the study area. The method is applied to the Salt Lake Valley Principal Aquifer in northern Utah to demonstrate its utility. Samples from 16 springs and mine tunnels in the adjacent Wasatch Mountains indicate that recharge temperature decreases with elevation at about the same rate as the mean annual air temperature, but is on average about 2??C cooler. Samples from 27 valley production wells yield recharge elevations ranging from the valley elevation (about 1500 m) to mid-mountain elevation (about 2500 m). Only six of the wells have recharge elevations less than 1800 m. Recharge elevations consistently greater than 2000 m in the southeastern part of the basin indicate that subsurface inflow constitutes most of the total recharge in this area. ?? 2003 Published by Elsevier Science B.V.

Translucent Radiosity: Efficiently Combining Diffuse Inter-Reflection and Subsurface Scattering.

PubMed

Sheng, Yu; Shi, Yulong; Wang, Lili; Narasimhan, Srinivasa G

2014-07-01

It is hard to efficiently model the light transport in scenes with translucent objects for interactive applications. The inter-reflection between objects and their environments and the subsurface scattering through the materials intertwine to produce visual effects like color bleeding, light glows, and soft shading. Monte-Carlo based approaches have demonstrated impressive results but are computationally expensive, and faster approaches model either only inter-reflection or only subsurface scattering. In this paper, we present a simple analytic model that combines diffuse inter-reflection and isotropic subsurface scattering. Our approach extends the classical work in radiosity by including a subsurface scattering matrix that operates in conjunction with the traditional form factor matrix. This subsurface scattering matrix can be constructed using analytic, measurement-based or simulation-based models and can capture both homogeneous and heterogeneous translucencies. Using a fast iterative solution to radiosity, we demonstrate scene relighting and dynamically varying object translucencies at near interactive rates.

Ocean (de)oxygenation from the Last Glacial Maximum to the twenty-first century: insights from Earth System models.

PubMed

Bopp, L; Resplandy, L; Untersee, A; Le Mezo, P; Kageyama, M

2017-09-13

All Earth System models project a consistent decrease in the oxygen content of oceans for the coming decades because of ocean warming, reduced ventilation and increased stratification. But large uncertainties for these future projections of ocean deoxygenation remain for the subsurface tropical oceans where the major oxygen minimum zones are located. Here, we combine global warming projections, model-based estimates of natural short-term variability, as well as data and model estimates of the Last Glacial Maximum (LGM) ocean oxygenation to gain some insights into the major mechanisms of oxygenation changes across these different time scales. We show that the primary uncertainty on future ocean deoxygenation in the subsurface tropical oceans is in fact controlled by a robust compensation between decreasing oxygen saturation (O 2sat ) due to warming and decreasing apparent oxygen utilization (AOU) due to increased ventilation of the corresponding water masses. Modelled short-term natural variability in subsurface oxygen levels also reveals a compensation between O 2sat and AOU, controlled by the latter. Finally, using a model simulation of the LGM, reproducing data-based reconstructions of past ocean (de)oxygenation, we show that the deoxygenation trend of the subsurface ocean during deglaciation was controlled by a combination of warming-induced decreasing O 2sat and increasing AOU driven by a reduced ventilation of tropical subsurface waters.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'. © 2017 The Author(s).

Ocean (de)oxygenation from the Last Glacial Maximum to the twenty-first century: insights from Earth System models

NASA Astrophysics Data System (ADS)

Bopp, L.; Resplandy, L.; Untersee, A.; Le Mezo, P.; Kageyama, M.

2017-08-01

All Earth System models project a consistent decrease in the oxygen content of oceans for the coming decades because of ocean warming, reduced ventilation and increased stratification. But large uncertainties for these future projections of ocean deoxygenation remain for the subsurface tropical oceans where the major oxygen minimum zones are located. Here, we combine global warming projections, model-based estimates of natural short-term variability, as well as data and model estimates of the Last Glacial Maximum (LGM) ocean oxygenation to gain some insights into the major mechanisms of oxygenation changes across these different time scales. We show that the primary uncertainty on future ocean deoxygenation in the subsurface tropical oceans is in fact controlled by a robust compensation between decreasing oxygen saturation (O2sat) due to warming and decreasing apparent oxygen utilization (AOU) due to increased ventilation of the corresponding water masses. Modelled short-term natural variability in subsurface oxygen levels also reveals a compensation between O2sat and AOU, controlled by the latter. Finally, using a model simulation of the LGM, reproducing data-based reconstructions of past ocean (de)oxygenation, we show that the deoxygenation trend of the subsurface ocean during deglaciation was controlled by a combination of warming-induced decreasing O2sat and increasing AOU driven by a reduced ventilation of tropical subsurface waters. This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'.

Modeling the spatiotemporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape

DOE PAGES

Kumar, Jitendra; Collier, Nathan; Bisht, Gautam; ...

2016-09-27

Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to the atmosphere under warming climate scenarios. Ice-wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. This microtopography plays a critical role in regulating the fine-scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behavior under the current as well as changing climate. Here, we present an end-to-end effort for high-resolution numerical modeling of thermal hydrology at real-world fieldmore » sites, utilizing the best available data to characterize and parameterize the models. We also develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites near Barrow, Alaska, spanning across low to transitional to high-centered polygons, representing a broad polygonal tundra landscape. A multiphase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using a high-resolution lidar digital elevation model (DEM), microtopographic features of the landscape were characterized and represented in the high-resolution model mesh. The best available soil data from field observations and literature were utilized to represent the complex heterogeneous subsurface in the numerical model. Simulation results demonstrate the ability of the developed modeling approach to capture – without recourse to model calibration – several aspects of the complex thermal regimes across the sites, and provide insights into the critical role of polygonal tundra microtopography in regulating the thermal dynamics of the carbon-rich permafrost soils. Moreover, areas of significant disagreement between model results and observations highlight the importance of field-based observations of soil thermal and hydraulic properties for modeling-based studies of permafrost thermal dynamics, and provide motivation and guidance for future observations that will help address model and data gaps affecting our current understanding of the system.« less

STATE WATER RESOURCES RESEARCH INSTITUTE PROGRAM: GROUND WATER RESEARCH.

USGS Publications Warehouse

Burton, James S.; ,

1985-01-01

This paper updates a review of the accomplishments of the State Water Resources Research Program in ground water contamination research. The aim is to assess the progress made towards understanding the mechanisms of ground water contamination and based on this understanding, to suggest procedures for the prevention and control of ground water contamination. The following research areas are covered: (1) mechanisms of organic contaminant transport in the subsurface environment; (2) bacterial and viral contamination of ground water from landfills and septic tank systems; (3) fate and persistence of pesticides in the subsurface; (4) leachability and transport of ground water pollutants from coal production and utilization; and (5) pollution of ground water from mineral mining activities.

STUDY OF WATER QUALITY IMPROVEMENTS DURING RIVERBANK FILTRATION AT THREE MIDWESTERN UNITED STATES DRINKING WATER UTILITIES

EPA Science Inventory

Riverbank filtration (RBF) is a process during which surface water is subjected to subsurface flow prior to extraction from wells. During infiltration and soil passage, surface water is subjected to a combination of physical, chemical, and biological processes such as filtration...

Evaluation of Subsurface Engineered Barriers at Waste Sites

DTIC Science & Technology

1998-08-01

28 3-4 MATRIX FOR EVALUATING BARRIER CQA/CQC AGAINST ACCEPTABLE INDSUTRY PRACTICES...STANDARDS................................................................. 66 4-2 MATRIX FOR EVALUATING CAP AGAINST ACCEPTABLE INDSUTRY PRACTICES...stated previously, the most widely used technique for containment is the soil-bentonite slurry wall. It is typically the most economical , utilizes low

Geophysical Surveys for Locating Buried Utilities, Lake Pontchartrain Levees, New Orleans

DTIC Science & Technology

2014-06-01

4 Figure 3. GPR concepts...this study. Electromagnetic (EM) induction, magnetic, and ground penetrating radar ( GPR ) geophysical methods were evaluated to determine which...surveys GPR is a ground-based geophysical instrument that transmits high- frequency EM pulses into the subsurface. The GPR system consists of a

Process for guidance, containment, treatment, and imaging in a subsurface environment utilizing ferro-fluids

DOEpatents

Moridis, George J.; Oldenburg, Curtis M.

2001-01-01

Disclosed are processes for monitoring and control of underground contamination, which involve the application of ferrofluids. Two broad uses of ferrofluids are described: (1) to control liquid movement by the application of strong external magnetic fields; and (2) to image liquids by standard geophysical methods.

Two year measurement of nitrous oxide emission from high frequency surface and subsurface drip irrigations in pomegranate orchard

USDA-ARS?s Scientific Manuscript database

Building resiliency in California agriculture means utilizing adaptive farming practices that will produce better yields while overcoming the State’s current challenges, such as diminishing water supply and deteriorating water quality. In addition, California agriculture also needs to take proactive...

SUMMARY OF TECHNIQUES AND UNIQUE USES FOR DIRECT PUSH METHODS IN SITE CHARACTERIZATION ON CONTAMINATED FIELD SITES

EPA Science Inventory

Site characterization of subsurface contaminant transport is often hampered by a lack of knowledge of site heterogeneity and temporal variations in hydrogeochemistry. Two case studies are reviewed to illustrate the utility of macro-scale mapping information along with spatially-...

The Large Scale Distribution of Water Ice in the Polar Regions of the Moon

NASA Astrophysics Data System (ADS)

Jordan, A.; Wilson, J. K.; Schwadron, N.; Spence, H. E.

2017-12-01

For in situ resource utilization, one must know where water ice is on the Moon. Many datasets have revealed both surface deposits of water ice and subsurface deposits of hydrogen near the lunar poles, but it has proved difficult to resolve the differences among the locations of these deposits. Despite these datasets disagreeing on how deposits are distributed on small scales, we show that most of these datasets do agree on the large scale distribution of water ice. We present data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO), LRO's Lunar Exploration Neutron Detector (LEND), the Neutron Spectrometer on Lunar Prospector (LPNS), LRO's Lyman Alpha Mapping Project (LAMP), LRO's Lunar Orbiter Laser Altimeter (LOLA), and Chandrayaan-1's Moon Mineralogy Mapper (M3). All, including those that show clear evidence for water ice, reveal surprisingly similar trends with latitude, suggesting that both surface and subsurface datasets are measuring ice. All show that water ice increases towards the poles, and most demonstrate that its signature appears at about ±70° latitude and increases poleward. This is consistent with simulations of how surface and subsurface cold traps are distributed with latitude. This large scale agreement constrains the origin of the ice, suggesting that an ancient cometary impact (or impacts) created a large scale deposit that has been rendered locally heterogeneous by subsequent impacts. Furthermore, it also shows that water ice may be available down to ±70°—latitudes that are more accessible than the poles for landing.

Recent Advances in Microbial Single Cell Genomics Technology and Applications

NASA Astrophysics Data System (ADS)

Stepanauskas, R.

2016-02-01

Single cell genomics is increasingly utilized as a powerful tool to decipher the metabolic potential, evolutionary histories and in situ interactions of environmental microorganisms. This transformative technology recovers extensive information from cultivation-unbiased samples of individual, unicellular organisms. Thus, it does not require data binning into arbitrary phylogenetic or functional groups and therefore is highly compatible with agent-based modeling approaches. I will present several technological advances in this field, which significantly improve genomic data recovery from individual cells and provide direct linkages between cell's genomic and phenotypic properties. I will also demonstrate how these new technical capabilities help understanding the metabolic potential and viral infections of the "microbial dark matter" inhabiting aquatic and subsurface environments.

Reflection Acoustic Microscopy for Micro-NDE.

DTIC Science & Technology

1983-02-01

WORDS (Coni, wu rere side. 14 It noeeeey And Idenify1 by block esife) Nondestructive Evaluation Acoustic Microscopy I Subsurface Imaging Pulsecio Cmrsin... subsurface imaging is presented and it is shown that with such lenses it is possible to obtain good focussing performance over a wide depth range...typically few millimeters at 50 MHz. A major problem in subsurface imaging derives from the large reflection obtained frnm the surface, and the small amount

Subsurface condition evaluation for asphalt pavement preservation treatments.

DOT National Transportation Integrated Search

2013-04-01

This report presents a case study on the SR70 section with microsurface for understanding its performance; a development of a : methodology for evaluating the asphalt pavement subsurface condition for applying pavement preservation treatments; and...

Detection of Subsurface Material Separation in Shuttle Orbiter Slip-Side Joggle Region of the Wing Leading Edge using Infrared Imaging Data from Arc Jet Tests

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran; Walker, Sandra P.

2009-01-01

The objective of the present study was to determine whether infrared imaging (IR) surface temperature data obtained during arc-jet tests of Space Shuttle Orbiter s reinforced carbon-carbon (RCC) wing leading edge panel slip-side joggle region could be used to detect presence of subsurface material separation, and if so, to determine when separation occurs during the simulated entry profile. Recent thermostructural studies have indicated thermally induced interlaminar normal stress concentrations at the substrate/coating interface in the curved joggle region can result in local subsurface material separation, with the separation predicted to occur during approach to peak heating during reentry. The present study was an attempt to determine experimentally when subsurface material separations occur. A simplified thermal model of a flat RCC panel with subsurface material separation was developed and used to infer general surface temperature trends due to the presence of subsurface material separation. IR data from previously conducted arc-jet tests on three test specimens were analyzed: one without subsurface material separation either pre or post test, one with pre test separation, and one with separation developing during test. The simplified thermal model trend predictions along with comparison of experimental IR data of the three test specimens were used to successfully infer material separation from the arc-jet test data. Furthermore, for the test specimen that had developed subsurface material separation during the arc-jet tests, the initiation of separation appeared to occur during the ramp up to the peak heating condition, where test specimen temperature went from 2500 to 2800 F.

Investigation of Coastal Hydrogeology Utilizing Geophysical and Geochemical Tools along the Broward County Coast, Florida

USGS Publications Warehouse

Reich, Christopher D.; Swarzenski, Peter W.; Greenwood, W. Jason; Wiese, Dana S.

2008-01-01

Geophysical (CHIRP, boomer, and continuous direct-current resistivity) and geochemical tracer studies (continuous and time-series 222Radon) were conducted along the Broward County coast from Port Everglades to Hillsboro Inlet, Florida. Simultaneous seismic, direct-current resistivity, and radon surveys in the coastal waters provided information to characterize the geologic framework and identify potential groundwater-discharge sites. Time-series radon at the Nova Southeastern University National Coral Reef Institute (NSU/NCRI) seawall indicated a very strong tidally modulated discharge of ground water with 222Rn activities ranging from 4 to 10 disintegrations per minute per liter depending on tidal stage. CHIRP seismic data provided very detailed bottom profiles (i.e., bathymetry); however, acoustic penetration was poor and resulted in no observed subsurface geologic structure. Boomer data, on the other hand, showed features that are indicative of karst, antecedent topography (buried reefs), and sand-filled troughs. Continuous resistivity profiling (CRP) data showed slight variability in the subsurface along the coast. Subtle changes in subsurface resistivity between nearshore (higher values) and offshore (lower values) profiles may indicate either a freshening of subsurface water nearshore or a change in sediment porosity or lithology. Further lithologic and hydrologic controls from sediment or rock cores or well data are needed to constrain the variability in CRP data.

Isolation and Characterization of Surface and Subsurface Bacteria in Seawater of Mantanani Island, Kota Belud, Sabah by Direct and Enrichment Techniques

NASA Astrophysics Data System (ADS)

Benard, L. D.; Tuah, P. M.; Suadin, E. G.; Jamian, N.

2015-04-01

The distribution of hydrocarbon-utilizing bacterial may vary between surface and subsurface of the seawater. One of the identified contributors is the Total Petroleum Hydrocarbon. The isolation and characterization of bacteria using Direct and Enrichment techniques helps in identifying dominant bacterial populations in seawater of Mantanani Island, Kota Belud, Sabah, potential of further investigation as hydrocarbon degrader. Crude oil (5% v/v) was added as the carbon source for bacteria in Enrichment technique. For surface seawater, the highest population of bacteria identified for both Direct and Enrichment technique were 2.60 × 107 CFU/mL and 3.84 × 106 CFU/mL respectively. Meanwhile, for subsurface seawater, the highest population of bacteria identified for both Direct and Enrichment technique were 5.21 × 106 CFU/mL and 8.99 × 107 CFU/mL respectively. Dominant species in surface seawater were characterized as Marinobacter hydrocarbonoclasticus-RMSF-C1 and RMSF-C2 and Alcanivorax borkumensis-RMSF-C3, RMSF-C4 and RMSF-C5. As for subsurface seawater, dominant species were characterized as Pseudomonas luteola-SSBR-W1, Burkholderia cepacia-SSBR-C1, Rhizobium radiobacter- SSBR-C3 and Leuconostoc-cremois -SSBR-C4.

Modeling of Composite Scenes Using Wires, Plates and Dielectric Parallelized (WIPL-DP)

DTIC Science & Technology

2006-06-01

formation and solves the data communications problem. The ability to perform subsurface imaging to depths of 200’ have already been demonstrated by...perform subsurface imaging to depths of 200’ have already been demonstrated by Brown in [3] and presented in Figure 3 above. Furthermore, reference [3...transmitter platform for use in image formation and solves the data communications problem. The ability to perform subsurface imaging to depths of 200

Relating sub-surface ice features to physiological stress in a climate sensitive mammal, the American pika (Ochotona princeps).

PubMed

Wilkening, Jennifer L; Ray, Chris; Varner, Johanna

2015-01-01

The American pika (Ochotona princeps) is considered a sentinel species for detecting ecological effects of climate change. Pikas are declining within a large portion of their range, and ongoing research suggests loss of sub-surface ice as a mechanism. However, no studies have demonstrated physiological responses of pikas to sub-surface ice features. Here we present the first analysis of physiological stress in pikas living in and adjacent to habitats underlain by ice. Fresh fecal samples were collected non-invasively from two adjacent sites in the Rocky Mountains (one with sub-surface ice and one without) and analyzed for glucocorticoid metabolites (GCM). We also measured sub-surface microclimates in each habitat. Results indicate lower GCM concentration in sites with sub-surface ice, suggesting that pikas are less stressed in favorable microclimates resulting from sub-surface ice features. GCM response was well predicted by habitat characteristics associated with sub-surface ice features, such as lower mean summer temperatures. These results suggest that pikas inhabiting areas without sub-surface ice features are experiencing higher levels of physiological stress and may be more susceptible to changing climates. Although post-deposition environmental effects can confound analyses based on fecal GCM, we found no evidence for such effects in this study. Sub-surface ice features are key to water cycling and storage and will likely represent an increasingly important component of water resources in a warming climate. Fecal samples collected from additional watersheds as part of current pika monitoring programs could be used to further characterize relationships between pika stress and sub-surface ice features.

An Autonomous Cryobot Synthetic Aperture Radar for Subsurface Exploration of Europa

NASA Astrophysics Data System (ADS)

Pradhan, O.; Gasiewski, A. J.

2015-12-01

We present the design and field testing of a forward-looking end-fire synthetic aperture radar (SAR) for the 'Very deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice Explorer' (VALKYRIE) ice-penetrating cryobot. This design demonstrates critical technologies that will support an eventual landing and ice penetrating mission to Jupiter's icy moon, Europa. Results proving the feasibility of an end-fire SAR system for vehicle guidance and obstacle avoidance in a sub-surface ice environment will be presented. Data collected by the SAR will also be used for constructing sub-surface images of the glacier which can be used for: (i) mapping of englacial features such as crevasses, moulins, and embedded liquid water and (ii) ice-depth and glacier bed analysis to construct digital elevation models (DEM) that can help in the selection of crybot trajectories and future drill sites for extracting long-term climate records. The project consists of three parts, (i) design of an array of four conformal cavity-backed log-periodic folded slot dipole array (LPFSA) antennas that form agile radiating elements, (ii) design of a radar system that includes RF signal generation, 4x4 transmit-receive antenna switching and isolation and digital SAR data processing and (iii) field testing of the SAR in melt holes. The antennas have been designed, fabricated, and lab tested at the Center for Environmental Technology (CET) at CU-Boulder. The radar system was also designed and integrated at CET utilizing rugged RF components and FPGA based digital processing. Field testing was performed in conjunction with VALKYRIE tests by Stone Aerospace in June, 2015 on Matanuska Glacier, Alaska. The antennas are designed to operate inside ice while being immersed in a thin layer of surrounding low-conductivity melt water. Small holes in the corners of the cavities allow flooding of these cavities with the same melt-water thus allowing for quarter-wavelength cavity-backed reflection. Testing of the antenna array was first carried out by characterizing their operation inside a large ice block at the Stone Aerospace facility in Austin, TX. The complete radar system was then tested on the Matanuska glacier in Alaska, which is an effective Earth analog to Europan sub-surface exploration.

Power systems utilizing the heat of produced formation fluid

DOEpatents

Lambirth, Gene Richard [Houston, TX

2011-01-11

Systems, methods, and heaters for treating a subsurface formation are described herein. At least one method includes treating a hydrocarbon containing formation. The method may include providing heat to the formation; producing heated fluid from the formation; and generating electricity from at least a portion of the heated fluid using a Kalina cycle.

Characterization of two subsurface H2-utilizing bacteria, Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov., and their ecological roles.

PubMed

Krumholz, L R; Harris, S H; Tay, S T; Suflita, J M

1999-06-01

We examined the relative roles of acetogenic and sulfate-reducing bacteria in H2 consumption in a previously characterized subsurface sandstone ecosystem. Enrichment cultures originally inoculated with ground sandstone material obtained from a Cretaceous formation in central New Mexico were grown with hydrogen in a mineral medium supplemented with 0.02% yeast extract. Sulfate reduction and acetogenesis occurred in these cultures, and the two most abundant organisms carrying out the reactions were isolated. Based on 16S rRNA analysis data and on substrate utilization patterns, these organisms were named Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov. The steady-state H2 concentrations measured in sandstone-sediment slurries (threshold concentration, 5 nM), in pure cultures of sulfate reducers (threshold concentration, 2 nM), and in pure cultures of acetogens (threshold concentrations 195 to 414 nM) suggest that sulfate reduction is the dominant terminal electron-accepting process in the ecosystem examined. In an experiment in which direct competition for H2 between D. hypogeium and A. psammolithicum was examined, sulfate reduction was the dominant process.

An approach to quantum-computational hydrologic inverse analysis

DOE PAGES

O'Malley, Daniel

2018-05-02

Making predictions about flow and transport in an aquifer requires knowledge of the heterogeneous properties of the aquifer such as permeability. Computational methods for inverse analysis are commonly used to infer these properties from quantities that are more readily observable such as hydraulic head. We present a method for computational inverse analysis that utilizes a type of quantum computer called a quantum annealer. While quantum computing is in an early stage compared to classical computing, we demonstrate that it is sufficiently developed that it can be used to solve certain subsurface flow problems. We utilize a D-Wave 2X quantum annealermore » to solve 1D and 2D hydrologic inverse problems that, while small by modern standards, are similar in size and sometimes larger than hydrologic inverse problems that were solved with early classical computers. Our results and the rapid progress being made with quantum computing hardware indicate that the era of quantum-computational hydrology may not be too far in the future.« less

An approach to quantum-computational hydrologic inverse analysis.

PubMed

O'Malley, Daniel

2018-05-02

Making predictions about flow and transport in an aquifer requires knowledge of the heterogeneous properties of the aquifer such as permeability. Computational methods for inverse analysis are commonly used to infer these properties from quantities that are more readily observable such as hydraulic head. We present a method for computational inverse analysis that utilizes a type of quantum computer called a quantum annealer. While quantum computing is in an early stage compared to classical computing, we demonstrate that it is sufficiently developed that it can be used to solve certain subsurface flow problems. We utilize a D-Wave 2X quantum annealer to solve 1D and 2D hydrologic inverse problems that, while small by modern standards, are similar in size and sometimes larger than hydrologic inverse problems that were solved with early classical computers. Our results and the rapid progress being made with quantum computing hardware indicate that the era of quantum-computational hydrology may not be too far in the future.

An approach to quantum-computational hydrologic inverse analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Malley, Daniel

Making predictions about flow and transport in an aquifer requires knowledge of the heterogeneous properties of the aquifer such as permeability. Computational methods for inverse analysis are commonly used to infer these properties from quantities that are more readily observable such as hydraulic head. We present a method for computational inverse analysis that utilizes a type of quantum computer called a quantum annealer. While quantum computing is in an early stage compared to classical computing, we demonstrate that it is sufficiently developed that it can be used to solve certain subsurface flow problems. We utilize a D-Wave 2X quantum annealermore » to solve 1D and 2D hydrologic inverse problems that, while small by modern standards, are similar in size and sometimes larger than hydrologic inverse problems that were solved with early classical computers. Our results and the rapid progress being made with quantum computing hardware indicate that the era of quantum-computational hydrology may not be too far in the future.« less

Clays and Carbonates in a Groundwater-Fed 3.8 Ga Martian Lake: Insights to Subsurface Habitability on Mars

NASA Technical Reports Server (NTRS)

Michalski, Joseph; Niles, Paul

2015-01-01

On Earth, the deep biosphere remains a largely unexplored, but clearly important carbon reservoir. Results from some uplifted central peaks in craters on Mars indicate that substantial carbon was also present at depth and might have helped sustain a deep biosphere. In fact, many factors relevant to deep biosphere habitability are more favorable on Mars than on Earth (e.g. porosity of the crust, geothermal gradient). Future exploration of Mars should include landing sites where materials have been exhumed from depth by meteor impact or basins where subsurface fluids have emerged, carrying clues to subsurface habitability. One of the most astrobiologically interesting sites on Mars McLaughlin Crater, a 93 km-diameter impact crater that formed approximately 4 b.y. ago. On the floor of the crater is a stratigraphic section of subhorizontal, layered sedimentary rocks with strong spectroscopic evidence for Fe-rich clay minerals and Mg-rich carbonates, which we interpret as ancient lacustrine deposits. The fluids that formed these materials likely originated in the subsurface, based on the paucity of channels leading into the crater basin and the fact that this is one of the deepest basins on Mars - a good candidate to have experienced upwelling of subsurface fluids. Therefore, the deposits within McLaughlin crater provide insight into subsurface processes on Mars. In this presentation, we will discuss the habitability of the martian subsurface as well as the geology of McLaughlin Crater and the possibility to detect biomarkers at that site with a future landed mission.

Field Evaluation of Advanced Methods of Subsurface Exploration for Transit Tunneling

DOT National Transportation Integrated Search

1980-06-01

This report presents the results of a field evaluation of advanced methods of subsurface exploration on an ongoing urban rapid transit tunneling project. The objective of this study is to evaluate, through a field demonstration project, the feasibili...

Bacterial communities associated with subsurface geochemical processes in continental serpentinite springs.

PubMed

Brazelton, William J; Morrill, Penny L; Szponar, Natalie; Schrenk, Matthew O

2013-07-01

Reactions associated with the geochemical process of serpentinization can generate copious quantities of hydrogen and low-molecular-weight organic carbon compounds, which may provide energy and nutrients to sustain subsurface microbial communities independently of the photosynthetically supported surface biosphere. Previous microbial ecology studies have tested this hypothesis in deep sea hydrothermal vents, such as the Lost City hydrothermal field. This study applied similar methods, including molecular fingerprinting and tag sequencing of the 16S rRNA gene, to ultrabasic continental springs emanating from serpentinizing ultramafic rocks. These molecular surveys were linked with geochemical measurements of the fluids in an interdisciplinary approach designed to distinguish potential subsurface organisms from those derived from surface habitats. The betaproteobacterial genus Hydrogenophaga was identified as a likely inhabitant of transition zones where hydrogen-enriched subsurface fluids mix with oxygenated surface water. The Firmicutes genus Erysipelothrix was most strongly correlated with geochemical factors indicative of subsurface fluids and was identified as the most likely inhabitant of a serpentinization-powered subsurface biosphere. Both of these taxa have been identified in multiple hydrogen-enriched subsurface habitats worldwide, and the results of this study contribute to an emerging biogeographic pattern in which Betaproteobacteria occur in near-surface mixing zones and Firmicutes are present in deeper, anoxic subsurface habitats.

Bacterial Communities Associated with Subsurface Geochemical Processes in Continental Serpentinite Springs

PubMed Central

Morrill, Penny L.; Szponar, Natalie; Schrenk, Matthew O.

2013-01-01

Reactions associated with the geochemical process of serpentinization can generate copious quantities of hydrogen and low-molecular-weight organic carbon compounds, which may provide energy and nutrients to sustain subsurface microbial communities independently of the photosynthetically supported surface biosphere. Previous microbial ecology studies have tested this hypothesis in deep sea hydrothermal vents, such as the Lost City hydrothermal field. This study applied similar methods, including molecular fingerprinting and tag sequencing of the 16S rRNA gene, to ultrabasic continental springs emanating from serpentinizing ultramafic rocks. These molecular surveys were linked with geochemical measurements of the fluids in an interdisciplinary approach designed to distinguish potential subsurface organisms from those derived from surface habitats. The betaproteobacterial genus Hydrogenophaga was identified as a likely inhabitant of transition zones where hydrogen-enriched subsurface fluids mix with oxygenated surface water. The Firmicutes genus Erysipelothrix was most strongly correlated with geochemical factors indicative of subsurface fluids and was identified as the most likely inhabitant of a serpentinization-powered subsurface biosphere. Both of these taxa have been identified in multiple hydrogen-enriched subsurface habitats worldwide, and the results of this study contribute to an emerging biogeographic pattern in which Betaproteobacteria occur in near-surface mixing zones and Firmicutes are present in deeper, anoxic subsurface habitats. PMID:23584766

The Role of Subsurface Properties on Transport of Water and Trace Gases: 1D Simulations at Selected Mars Landing Sites.

NASA Astrophysics Data System (ADS)

Karatekin, O.; Gloesener, E.; Dehant, V. M. A.

2017-12-01

In this work, water ice stability and water vapour transport through porous martian subsurface are studied using a 1D diffusive model. The role of adsorption on water transfer in martian conditions is investigated as well as the range of parameters that have the largest effect on gas transport. In addition, adsorption kinetics is considered to examine its influence on the water vapor exchange between the subsurface and the atmosphere. As methane has been detected in the martian atmosphere, the subsurface model is then used to study methane diffusion in the CH4/CO2/H2O system from variable depths under the surface. The results of subsurface gas transport at selected locations/landing sites are shown and implications for present/future observations are discussed.

An analysis of the lithology to resistivity relationships using airborne EM and boreholes

NASA Astrophysics Data System (ADS)

Barfod, Adrian A. S.; Christiansen, Anders V.; Møller, Ingelise

2014-05-01

We present a study of the relationship between dense airborne SkyTEM resistivity data and sparse lithological borehole data. Understanding the geological structures of the subsurface is of great importance to hydrogeological surveys. Large scale geological information can be gathered directly from boreholes or indirectly from large geophysical surveys. Borehole data provides detailed lithological information only at the position of the borehole and, due to the sparse nature of boreholes, they rarely provide sufficient information needed for high-accuracy groundwater models. Airborne geophysical data, on the other hand, provide dense spatial coverage, but are only indirectly bearing information on lithology through the resistivity models. Hitherherto, the integration of the geophysical data into geological and hydrogeological models has been often subjective, largely un-documented and painstakingly manual. This project presents a detailed study of the relationships between resistivity data and lithological borehole data. The purpose is to objectively describe the relationships between lithology and geophysical parameters and to document these relationships. This project has focused on utilizing preexisting datasets from the Danish national borehole database (JUPITER) and national geophysical database (GERDA). The study presented here is from the Norsminde catchment area (208 sq. km), situated in the municipality of Odder, Denmark. The Norsminde area contains a total of 758 boreholes and 106,770 SkyTEM soundings. The large amounts of data make the Norsminde area ideal for studying the relationship between geophysical data and lithological data. The subsurface is discretized into 20 cm horizontal sampling intervals from the highest elevation point to the depth of the deepest borehole. For each of these intervals a resistivity value is calculated at the position of the boreholes using a kriging formulation. The lithology data from the boreholes are then used to categorize the interpolated resistivity values according to lithology. The end result of this comparison is resistivity distributions for different lithology categories. The distributions provide detailed objective information of the resistivity properties of the subsurface and are a documentation of the resistivity imaging of the geological lithologies. We show that different lithologies are mapped at distinctively different resistivities but also that the geophysical inversion strategies influences the resulting distributions significantly.

Immunological techniques as tools to characterize the subsurface microbial community at a trichloroethylene contaminated site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fliermans, C.B.; Dougherty, J.M.; Franck, M.M.

Effective in situ bioremediation strategies require an understanding of the effects pollutants and remediation techniques have on subsurface microbial communities. Therefore, detailed characterization of a site`s microbial communities is important. Subsurface sediment borings and water samples were collected from a trichloroethylene (TCE) contaminated site, before and after horizontal well in situ air stripping and bioventing, as well as during methane injection for stimulation of methane-utilizing microorganisms. Subsamples were processed for heterotrophic plate counts, acridine orange direct counts (AODC), community diversity, direct fluorescent antibodies (DFA) enumeration for several nitrogen-transforming bacteria, and Biolog {reg_sign} evaluation of enzyme activity in collected water samples.more » Plate counts were higher in near-surface depths than in the vadose zone sediment samples. During the in situ air stripping and bioventing, counts increased at or near the saturated zone, remained elevated throughout the aquifer, but did not change significantly after the air stripping. Sporadic increases in plate counts at different depths as well as increased diversity appeared to be linked to differing lithologies. AODCs were orders of magnitude higher than plate counts and remained relatively constant with depth except for slight increases near the surface depths and the capillary fringe. Nitrogen-transforming bacteria, as measured by serospecific DFA, were greatly affected both by the in situ air stripping and the methane injection. Biolog{reg_sign} activity appeared to increase with subsurface stimulation both by air and methane. The complexity of subsurface systems makes the use of selective monitoring tools imperative.« less

Solving subsurface structural problems using a computer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witte, D.M.

1987-02-01

Until recently, the solution of subsurface structural problems has required a combination of graphical construction, trigonometry, time, and patience. Recent advances in software available for both mainframe and microcomputers now reduce the time and potential error of these calculations by an order of magnitude. Software for analysis of deviated wells, three point problems, apparent dip, apparent thickness, and the intersection of two planes, as well as the plotting and interpretation of these data can be used to allow timely and accurate exploration or operational decisions. The available computer software provides a set of utilities, or tools, rather than a comprehensive,more » intelligent system. The burden for selection of appropriate techniques, computation methods, and interpretations still lies with the explorationist user.« less

Deep subsurface life in Bengal Fan sediments (IODP Exp. 354)

NASA Astrophysics Data System (ADS)

Adhikari, R. R.; Heuer, V. B.; Elvert, M.; Kallmeyer, J.; Kitte, J. A.; Wörmer, L.; Hinrichs, K. U.

2017-12-01

We collected Bengal Fan sediment samples along a 8°N transect during International Ocean Discovery Program Expedition 354 (February - March 2015, Singapore - Colombo, Sri Lanka) to study subseafloor life in this, as yet unstudied, area. Among other biogeochemical parameters, we quantified microbial biomass by analyzing prokaryotic cells using epifluorescence microscopy after detaching cells from the sediment, and bacterial endospores by analyzing the diagnostic biomarker dipicolinic acid (DPA) by detection of fluorescence of the terbium-DPA complex. To gain understanding of total microbial activity, we quantified hydrogen utilization potential of hydrogenase enzymes, which are ubiquitous in subsurface microorganisms, by using a tritium assay. We measured highest cell concentrations of ca. 108 cells g-1 in shallow sediments close to the seafloor. These concentrations are one to two orders of magnitude lower than in most marine continental margin settings [1]. Similar to the global trend [1], cell concentrations decreased with depth according to a power-law function. Endospore concentrations scattered between ca. 105 and 107 cells g-1 sediment at all sites and depths. We could not observe a clear relationship of endospore concentration and sediment depth; instead, it appears to be linked to lithology and total organic carbon content. Bulk Hydrogenase enzyme activity ranged from nmolar to μmolar range of H2 g-1d-1. Similar to previous observations [2], per-cell hydrogen utilization depends on vertical biogeochemical zones, which could be due to the differences in hydrogen utilization requirements/efficiency of the respective metabolic processes such as sulfate reduction, methanogenesis, fermentation etc. Bengal fan is highly dynamic due to channel and levee systems and the sediments are dominated by turbidites, thick sand layers and hemipelagic deposits, which may control biogeochemical zonation. Based on our microbial biomass and activity data, we suggest that the nature, quality and origin of sedimentary material influence the deep subsurface life. [1] Kallmeyer et al., (2012) PNAS 109(40), 16213-16216 [2] Adhikari et al., (2016) Frontiers in Microbiology 7:8

Relating Sub-Surface Ice Features to Physiological Stress in a Climate Sensitive Mammal, the American Pika (Ochotona princeps)

PubMed Central

Wilkening, Jennifer L.; Ray, Chris; Varner, Johanna

2015-01-01

The American pika (Ochotona princeps) is considered a sentinel species for detecting ecological effects of climate change. Pikas are declining within a large portion of their range, and ongoing research suggests loss of sub-surface ice as a mechanism. However, no studies have demonstrated physiological responses of pikas to sub-surface ice features. Here we present the first analysis of physiological stress in pikas living in and adjacent to habitats underlain by ice. Fresh fecal samples were collected non-invasively from two adjacent sites in the Rocky Mountains (one with sub-surface ice and one without) and analyzed for glucocorticoid metabolites (GCM). We also measured sub-surface microclimates in each habitat. Results indicate lower GCM concentration in sites with sub-surface ice, suggesting that pikas are less stressed in favorable microclimates resulting from sub-surface ice features. GCM response was well predicted by habitat characteristics associated with sub-surface ice features, such as lower mean summer temperatures. These results suggest that pikas inhabiting areas without sub-surface ice features are experiencing higher levels of physiological stress and may be more susceptible to changing climates. Although post-deposition environmental effects can confound analyses based on fecal GCM, we found no evidence for such effects in this study. Sub-surface ice features are key to water cycling and storage and will likely represent an increasingly important component of water resources in a warming climate. Fecal samples collected from additional watersheds as part of current pika monitoring programs could be used to further characterize relationships between pika stress and sub-surface ice features. PMID:25803587

ENGINEERING ISSUE: IN SITU BIOREMEDIATION OF CONTAMINATED UNSATURATED SUBSURFACE SOILS

EPA Science Inventory

An emerging technology for the remediation of unsaturated subsurface soils involves the use of microorganisms to degrade contaminants which are present in such soils. Understanding the processes which drive in situ bioremediation, as well as the effectiveness and efficiency of th...

VIRUS TRANSPORT IN PHYSICALLY AND GEOCHEMICALLY HETEROGENEOUS SUBSURFACE POROUS MEDIA. (R826179)

EPA Science Inventory

A two-dimensional model for virus transport in physically and geochemically heterogeneous subsurface porous media is presented. The model involves solution of the advection–dispersion equation, which additionally considers virus inactivation in the solution, as well as ...

Remote sensing of land-based voids using computer enhanced infrared thermography

NASA Astrophysics Data System (ADS)

Weil, Gary J.

1989-10-01

Experiments are described in which computer-enhanced infrared thermography techniques are used to detect and describe subsurface land-based voids, such as voids surrounding buried utility pipes, voids in concrete structures such as airport taxiways, abandoned buried utility storage tanks, and caves and underground shelters. Infrared thermography also helps to evaluate bridge deck systems, highway pavements, and garage concrete. The IR thermography techniques make it possible to survey large areas quickly and efficiently. The paper also surveys the advantages and limitations of thermographic testing in comparison with other forms of NDT.

Enhanced recharge rates and altered recharge sensitivity to climate variability through subsurface heterogeneity

NASA Astrophysics Data System (ADS)

Hartmann, Andreas; Gleeson, Tom; Wada, Yoshihide; Wagener, Thorsten

2017-04-01

Karst aquifers in Europe are an important source of fresh water contributing up to half of the total drinking water supply in some countries. Karstic groundwater recharge is one of the most important components of the water balance of karst systems as it feeds the karst aquifers. Presently available large-scale hydrological models do not consider karst heterogeneity adequately. Projections of current and potential future groundwater recharge of Europe's karst aquifers are therefore unclear. In this study we compare simulations of present (1991-2010) and future (2080-2099) recharge using two different models to simulate groundwater recharge processes. One model includes karst processes (subsurface heterogeneity, lateral flow and concentrated recharge), while the other is based on the conceptual understanding of common hydrological systems (homogeneous subsurface, saturation excess overland flow). Both models are driven by the bias-corrected 5 GCMs of the ISI-MIP project (RCP8.5). To further assess sensitivity of groundwater recharge to climate variability, we calculate the elasticity of recharge rates to annual precipitation, temperature and average intensity of rainfall events, which is the median change of recharge that corresponds to the median change of these climate variables within the present and future time period, respectively. Our model comparison shows that karst regions over Europe have enhanced recharge rates with greater inter-annual variability compared to those with more homogenous subsurface properties. Furthermore, the heterogeneous representation shows stronger elasticity concerning climate variability than the homogeneous subsurface representation. This difference tends to increase towards the future. Our results suggest that water management in regions with heterogeneous subsurface can expect a higher water availability than estimated by most of the current large-scale simulations, while measures should be taken to prepare for increasingly variable groundwater recharge rates.

Subsurface Stress Fields in FCC Single Crystal Anisotropic Contacts

NASA Technical Reports Server (NTRS)

Arakere, Nagaraj K.; Knudsen, Erik; Swanson, Gregory R.; Duke, Gregory; Ham-Battista, Gilda

2004-01-01

Single crystal superalloy turbine blades used in high pressure turbomachinery are subject to conditions of high temperature, triaxial steady and alternating stresses, fretting stresses in the blade attachment and damper contact locations, and exposure to high-pressure hydrogen. The blades are also subjected to extreme variations in temperature during start-up and shutdown transients. The most prevalent high cycle fatigue (HCF) failure modes observed in these blades during operation include crystallographic crack initiation/propagation on octahedral planes, and non-crystallographic initiation with crystallographic growth. Numerous cases of crack initiation and crack propagation at the blade leading edge tip, blade attachment regions, and damper contact locations have been documented. Understanding crack initiation/propagation under mixed-mode loading conditions is critical for establishing a systematic procedure for evaluating HCF life of single crystal turbine blades. This paper presents analytical and numerical techniques for evaluating two and three dimensional subsurface stress fields in anisotropic contacts. The subsurface stress results are required for evaluating contact fatigue life at damper contacts and dovetail attachment regions in single crystal nickel-base superalloy turbine blades. An analytical procedure is presented for evaluating the subsurface stresses in the elastic half-space, based on the adaptation of a stress function method outlined by Lekhnitskii. Numerical results are presented for cylindrical and spherical anisotropic contacts, using finite element analysis (FEA). Effects of crystal orientation on stress response and fatigue life are examined. Obtaining accurate subsurface stress results for anisotropic single crystal contact problems require extremely refined three-dimensional (3-D) finite element grids, especially in the edge of contact region. Obtaining resolved shear stresses (RSS) on the principal slip planes also involves considerable post-processing work. For these reasons it is very advantageous to develop analytical solution schemes for subsurface stresses, whenever possible.

3-D imaging of large scale buried structure by 1-D inversion of very early time electromagnetic (VETEM) data

USGS Publications Warehouse

Aydmer, A.A.; Chew, W.C.; Cui, T.J.; Wright, D.L.; Smith, D.V.; Abraham, J.D.

2001-01-01

A simple and efficient method for large scale three-dimensional (3-D) subsurface imaging of inhomogeneous background is presented. One-dimensional (1-D) multifrequency distorted Born iterative method (DBIM) is employed in the inversion. Simulation results utilizing synthetic scattering data are given. Calibration of the very early time electromagnetic (VETEM) experimental waveforms is detailed along with major problems encountered in practice and their solutions. This discussion is followed by the results of a large scale application of the method to the experimental data provided by the VETEM system of the U.S. Geological Survey. The method is shown to have a computational complexity that is promising for on-site inversion.

Ground-penetrating radar: use and misuse

NASA Astrophysics Data System (ADS)

Olhoeft, Gary R.

1999-10-01

Ground penetrating radar (GPR) has been used to explore the subsurface of the earth since 1929. Over the past 70 years, it has been widely used, misused and abused. Use includes agriculture, archaeology, environmental and geotechnical site characterization, minerals, groundwater and permafrost exploration, tunnel, utility, and unexploded ordnance location, dam inspection, and much more. Misuse includes mistaking above ground reflections for subsurface events or mapping things from off to the side as if they were directly below, synthetic aperture processing of dispersive data, minimum phase deconvolution, locating objects smaller than resolution limits of the wavelength in the ground, ignoring Fresnel zone limitations in mapping subsurface structure, processing radar data through seismic software packages without allowing for the differences, mapping the bottom of metal pipes from the top, claiming to see through thousands of feet of sediments, and more. GPR is also being abused as the regulatory environment changes and the radiofrequency spectrum is becoming more crowded by cellular phones, pagers, garage door openers, wireless computer networks, and the like. It is often thought to be a source of interference (though it never is) and it is increasingly interfered with by other radiofrequency transmitters.

Mapping the Upper Subsurface of MARS Using Radar Polarimetry

NASA Technical Reports Server (NTRS)

Carter, L. M.; Rincon, R.; Berkoski, L.

2012-01-01

Future human exploration of Mars will require detailed knowledge of the surface and upper several meters of the subsurface in potential landing sites. Likewise, many of the Planetary Science Decadal Survey science goals, such as understanding the history of Mars climate change, determining how the surface was altered through processes like volcanism and fluvial activity, and locating regions that may have been hospitable to life in the past, would be significantly advanced through mapping of the upper meters of the surface. Synthetic aperture radar (SAR) is the only remote sensing technique capable of penetrating through meters of material and imaging buried surfaces at high (meters to tens-of-meters) spatial resolution. SAR is capable of mapping the boundaries of buried units and radar polarimetry can provide quantitative information about the roughness of surface and subsurface units, depth of burial of stratigraphic units, and density of materials. Orbital SAR systems can obtain broad coverage at a spatial scale relevant to human and robotic surface operations. A polarimetric SAR system would greatly increase the safety and utility of future landed systems including sample caching.

Wells for In Situ Extraction of Volatiles from Regolith (WIEVR)

NASA Technical Reports Server (NTRS)

Walton, Otis R.

2013-01-01

A document discusses WIEVRs, a means to extract water ice more efficiently than previous approaches. This water may exist in subsurface deposits on the Moon, in many NEOs (Near- Earth Objects), and on Mars. The WIEVR approach utilizes heat from the Sun to vaporize subsurface ice; the water (or other volatile) vapor is transported to a surface collection vessel where it is condensed (and collected). The method does not involve mining and extracting regolith before removing the frozen volatiles, so it uses less energy and is less costly than approaches that require mining of regolith. The only drilling required for establishing the WIEVR collection/recovery system is a well-bore drill hole. In its simplest form, the WIEVRs will function without pumps, compressors, or other gas-moving equipment, relying instead on diffusive transport and thermally induced convection of the vaporized volatiles for transport to the collection location(s). These volatile extraction wells could represent a significant advance in extraction efficiency for recovery of frozen volatiles in subsurface deposits on the Moon, Mars, or other extraterrestrial bodies.

Biodegradability of pentachlorophenol in the environment: A literature review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakles, D.

1993-04-01

Pentachlorophenol has been widely used as a wood preserving agent for over 50 years to treat millions of electrical utility poles and crossarms. Treatment of poles with pentachlorophenol has in some cases resulted in contamination of soils, groundwater, and surface water. Environmental releases are a concern because of the potential toxicity of pentachlorophenol and its stringent regulation. Microbiological degradation of pentachlorophenol in environmental media has been demonstrated in numerous cases. The potential for pentachlorophenol to be biologically degraded is of interest to the electrical utility industry for two reasons. First, it is a factor in understanding the probable fate ofmore » pentachlorophenol where it has been released into the environment, and second, its biodegradability can potentially result in effective and economical treatment strategies for soils, water, and subsurface environments. The objective of this literature review is to collect a baseline of information on the biodegradability of pentachlorophenol in soils, surface water, and groundwater for the electric utility industry. The focus of the electric utility industry's interest in the environmental management and control of pentachlorophenol is primarily in the management of environmental media, particularly soils, that may have become incidentally contaminated with pentachlorophenol in association with the treatment, storage, or use of utility poles and crossarms. The review of the literature has found that [open quotes]unassisted[close quotes] biodegradation of pentachlorophenol in aquatic, soil, and subsurface environments may occur, presumably if there is an acclimated microbial population of sufficient density. Aerobic conditions appear to be most conducive to biodegradation in these cases. Several studies have shown that with an acclimated, mixed culture and conventional wastewater treatment approaches, pentachlorophenol can be effectively treated in water.« less

Biodegradability of pentachlorophenol in the environment: A literature review. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakles, D.

1993-04-01

Pentachlorophenol has been widely used as a wood preserving agent for over 50 years to treat millions of electrical utility poles and crossarms. Treatment of poles with pentachlorophenol has in some cases resulted in contamination of soils, groundwater, and surface water. Environmental releases are a concern because of the potential toxicity of pentachlorophenol and its stringent regulation. Microbiological degradation of pentachlorophenol in environmental media has been demonstrated in numerous cases. The potential for pentachlorophenol to be biologically degraded is of interest to the electrical utility industry for two reasons. First, it is a factor in understanding the probable fate ofmore » pentachlorophenol where it has been released into the environment, and second, its biodegradability can potentially result in effective and economical treatment strategies for soils, water, and subsurface environments. The objective of this literature review is to collect a baseline of information on the biodegradability of pentachlorophenol in soils, surface water, and groundwater for the electric utility industry. The focus of the electric utility industry`s interest in the environmental management and control of pentachlorophenol is primarily in the management of environmental media, particularly soils, that may have become incidentally contaminated with pentachlorophenol in association with the treatment, storage, or use of utility poles and crossarms. The review of the literature has found that {open_quotes}unassisted{close_quotes} biodegradation of pentachlorophenol in aquatic, soil, and subsurface environments may occur, presumably if there is an acclimated microbial population of sufficient density. Aerobic conditions appear to be most conducive to biodegradation in these cases. Several studies have shown that with an acclimated, mixed culture and conventional wastewater treatment approaches, pentachlorophenol can be effectively treated in water.« less

Ecohydrological dynamics of peatlands and adjacent upland forests in the Rocky Mountains

NASA Astrophysics Data System (ADS)

Millar, D.; Parsekian, A.; Mercer, J.; Ewers, B. E.; Mackay, D. S.; Williams, D. G.; Cooper, D. J.; Ronayne, M. J.

2017-12-01

Mountain peatlands are susceptible to a changing climate via changes in the water cycle. Understanding the impacts of such changes requires knowledge of the hydrological processes within these peatlands and in the upland forests that supply them with water. We investigated hydrological processes in peatland catchments in the Rocky Mountains by developing empirical models of groundwater dynamics, and are working to improve subsurface water dynamics in a ecohydrological process model, the Terrestrial Regional Ecosystem Exchange Simulator (TREES). Results from empirical models showed major differences in water budget components between two peatlands with differing climate, vegetation, and hydrogeological settings. Several-fold higher rates of evapotranspiration from the saturated zone, and groundwater inflow were observed for a sloping fen in southern Wyoming than that of a basin fen in southwestern Colorado, where rainfall was two-fold higher due to stronger influence of the North American monsoon. We also present ongoing work coupling stable water isotope and borehole nuclear magnetic resonance analyses to test which soil water pools (bound or mobile) are used by dominant upland and peatland vegetation in two catchments in southern Wyoming. These data are being used to test whether the root hydraulic mechanisms in TREES can simulate water uptake from these two soil water pools, and sap flux measurements are being used to evaluate simulated transpiration. Preliminary results from this work suggest that upland vegetation utilize tightly-bound soil water pools, as these pools comprise the largest amount of subsurface water (> 80%) in the vadose zone long after snow melt. Conversely, it appears that herbaceous peatland hydrophytes may preferentially utilize mobile soil water pools, since their roots extend below the water table. The results of this work are expected to increase predictive understanding of hydrological processes in these important ecosystems.

Optical coherence tomography (OCT) guided smart laser knife for cancer surgery (Conference Presentation)

NASA Astrophysics Data System (ADS)

Katta, Nitesh; Mcelroy, Austin; Estrada, Arnold; Milner, Thomas E.

2017-02-01

Neurological cancer surgeries require specialized tools that enhance imaging for precise cutting and removal of tissue without damaging adjacent neurological structures. The novel combination of high-resolution fast optical coherence tomography (OCT) alongside short pulsed nanosecond thulium (Tm) lasers offers stark advantages utilizing the superior beam quality, high volumetric tissue removal rates of thulium lasers with minimal residual thermal footprint in the tissue and avoiding damage to delicate sub-surface structures (e.g., nerves and microvessels); which has not been showcased before. A bench-top system is constructed, using a 15W 1940nm nanosecond pulsed Tm fiber laser (500uJ pulse energy, 100ns pulse duration, 30kHz repetition rate) for removing tissue and a swept source laser (1310±70nm, 100kHz sweep rate) is utilized for OCT imaging, forming a combined Tm/OCT system - a smart laser knife. The OCT image-guidance informs the Tm laser for cutting/removal of targeted tissue structures. Tissue phantoms were constructed to demonstrate surgical incision with blood vessel avoidance on the surface where 2mm wide 600um deep cuts are executed around the vessel using OCT to guide the procedure. Cutting up to delicate subsurface blood vessels (2mm deep) is demonstrated while avoiding damage to their walls. A tissue removal rate of 5mm^3/sec is obtained from the bench-top system. We constructed a blow-off model to characterize Tm cut depths taking into account the absorption coefficients and beam delivery systems to compute Arrhenius damage integrals. The model is used to compare predicted tissue removal rate and residual thermal injury with experimental values in response to Tm laser-tissue modification.

Non-enzymatic U(VI) interactions with biogenic mackinawite

NASA Astrophysics Data System (ADS)

Veeramani, H.; Qafoku, N. P.; Kukkadapu, R. K.; Murayama, M.; Hochella, M. F.

2011-12-01

Reductive immobilization of hexavalent uranium [U(VI)] by stimulation of dissimilatory metal and/or sulfate reducing bacteria (DMRB or DSRB) has been extensively researched as a remediation strategy for subsurface U(VI) contamination. These bacteria derive energy by reducing oxidized metals as terminal electron acceptors, often utilizing organic substrates as electron donors. Thus, when evaluating the potential for in-situ uranium remediation in heterogeneous subsurface media, it is important to understand how the presence of alternative electron acceptors such as Fe(III) and sulfate affect U(VI) remediation and the long term behavior and reactivity of reduced uranium. Iron, an abundant subsurface element, represents a substantial sink for electrons from DMRB, and the reduction of Fe(III) leads to the formation of dissolved Fe(II) or to reactive biogenic Fe(II)- and mixed Fe(II)/Fe(III)- mineral phases. Consequently, abiotic U(VI) reduction by reactive forms of biogenic Fe(II) minerals could be a potentially important process for uranium immobilization. In our study, the DMRB Shewanella putrefaciens CN32 was used to synthesize a biogenic Fe(II)-bearing sulfide mineral: mackinawite, that has been characterized by XRD, SEM, HRTEM and Mössbauer spectroscopy. Batch experiments involving treated biogenic mackinawite and uranium (50:1 molar ratio) were carried out at room temperature under strict anoxic conditions. Following complete removal of uranium from solution, the biogenic mackinawite was analyzed by a suite of analytical techniques including XAS, HRTEM and Mössbauer spectroscopy to determine the speciation of uranium and investigate concomitant Fe(II)-phase transformation. Determining the speciation of uranium is critical to success of a remediation strategy. The present work elucidates non-enzymatic/abiotic molecular scale redox interactions between biogenic mackinawite and uranium.

Imaging the Subsurface with Upgoing Muons

NASA Astrophysics Data System (ADS)

Bonal, N.; Preston, L. A.; Schwellenbach, D.; Dreesen, W.; Green, A.

2014-12-01

We assess the feasibility of imaging the subsurface using upgoing muons. Traditional muon imaging focuses on more-prevalent downgoing muons. Muons are subatomic particles capable of penetrating the earth's crust several kilometers. Downgoing muons have been used to image the Pyramid of Khafre of Giza, various volcanoes, and smaller targets like cargo. Unfortunately, utilizing downgoing muons requires below-target detectors. For aboveground objects like a volcano, the detector is placed at the volcano's base and the top portion of the volcano is imaged. For underground targets like tunnels, the detector would have to be placed below the tunnel in a deeper tunnel or adjacent borehole, which can be costly and impractical for some locations. Additionally, detecting and characterizing subsurface features like voids from tunnels can be difficult. Typical characterization methods like sonar, seismic, and ground penetrating radar have shown mixed success. Voids have a marked density contrast with surrounding materials, so using methods sensitive to density variations would be ideal. High-energy cosmic ray muons are more sensitive to density variation than other phenomena, including gravity. Their absorption rate depends on the density of the materials through which they pass. Measurements of muon flux rate at differing directions provide density variations of the materials between the muon source (cosmic rays and neutrino interactions) and detector, much like a CAT scan. Currently, tomography using downgoing muons can resolve features to the sub-meter scale. We present results of exploratory work, which demonstrates that upgoing muon fluxes appear sufficient to achieve target detection within a few months. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Heat as a groundwater tracer in shallow and deep heterogeneous media: Analytical solution, spreadsheet tool, and field applications

USGS Publications Warehouse

Kurylyk, Barret L.; Irvine, Dylan J.; Carey, Sean K.; Briggs, Martin A.; Werkema, Dale D.; Bonham, Mariah

2017-01-01

Groundwater flow advects heat, and thus, the deviation of subsurface temperatures from an expected conduction‐dominated regime can be analysed to estimate vertical water fluxes. A number of analytical approaches have been proposed for using heat as a groundwater tracer, and these have typically assumed a homogeneous medium. However, heterogeneous thermal properties are ubiquitous in subsurface environments, both at the scale of geologic strata and at finer scales in streambeds. Herein, we apply the analytical solution of Shan and Bodvarsson (2004), developed for estimating vertical water fluxes in layered systems, in 2 new environments distinct from previous vadose zone applications. The utility of the solution for studying groundwater‐surface water exchange is demonstrated using temperature data collected from an upwelling streambed with sediment layers, and a simple sensitivity analysis using these data indicates the solution is relatively robust. Also, a deeper temperature profile recorded in a borehole in South Australia is analysed to estimate deeper water fluxes. The analytical solution is able to match observed thermal gradients, including the change in slope at sediment interfaces. Results indicate that not accounting for layering can yield errors in the magnitude and even direction of the inferred Darcy fluxes. A simple automated spreadsheet tool (Flux‐LM) is presented to allow users to input temperature and layer data and solve the inverse problem to estimate groundwater flux rates from shallow (e.g., <1 m) or deep (e.g., up to 100 m) profiles. The solution is not transient, and thus, it should be cautiously applied where diel signals propagate or in deeper zones where multi‐decadal surface signals have disturbed subsurface thermal regimes.

Shallow Subsurface Velocity Structure using the Ambient Noise for the Garhwal and Kumaon Himalaya.

NASA Astrophysics Data System (ADS)

LAL, S.; Joshi, A.; S.; P.

2017-12-01

Abstract: In this paper effort has been made to obtain one dimensional subsurface velocity structure using H/V spectral ratio method Nakamura (1989). The complete study shows that ambient noises are reflective of structural properties of underlying strata. Data has been obtained at stations from foothills of Himalaya up to higher Himalaya along road using strong motion accelerograph in the Garhwal and Kumaon Himalaya along the two transects lines. Noise data has been processed using the seismosignal software. The ratio between the Fourier amplitude spectra of the horizontal components to the vertical component of the ambient noise had been used to consider the site effects of the concerned site. The relation given by Lermo and Chavez-Garcia (1993) between the thickness of layer and average S- wave velocity of the sedimentary layer has been utilized to obtain sub surface velocity model. To fit the synthetic H/V curve with the observed H/V curve, technique given by Castellaro and Mulargia (2009) is used in the present study. This model is improved via forward modelling to give final one dimensional velocity structure at a particular station. Velocity structures obtained at all stations are used to obtain continuous velocity models for concerned area using Kringing interpolation, which is correlated with the geology and tectonic of region. Keywords: Ambient noise, H/V spectral ratio, Site characterization, Accelerograph, Velocity ReferencesNakamura Y (1989). A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. QR RTRI 30(1):25-30. Castellaro S, Mulargia F (2009). The effect of velocity inversions on H/V. PAGEOPH 166:567-592. Lermo, J., & Chavez-Garcia, F. J. (1993). Site effect evaluation using spectral ratios with only one station Bulletin Seismological Society of America, 83, 1574-1594.

Contamination assessment in microbiological sampling of the Eyreville core, Chesapeake Bay impact structure

USGS Publications Warehouse

Gronstal, A.L.; Voytek, M.A.; Kirshtein, J.D.; Von der, Heyde; Lowit, M.D.; Cockell, C.S.

2009-01-01

Knowledge of the deep subsurface biosphere is limited due to difficulties in recovering materials. Deep drilling projects provide access to the subsurface; however, contamination introduced during drilling poses a major obstacle in obtaining clean samples. To monitor contamination during the 2005 International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) deep drilling of the Chesapeake Bay impact structure, four methods were utilized. Fluorescent microspheres were used to mimic the ability of contaminant cells to enter samples through fractures in the core material during retrieval. Drilling mud was infused with a chemical tracer (Halon 1211) in order to monitor penetration of mud into cores. Pore water from samples was examined using excitation-emission matrix (EEM) fl uorescence spectroscopy to characterize dissolved organic carbon (DOC) present at various depths. DOC signatures at depth were compared to signatures from drilling mud in order to identify potential contamination. Finally, microbial contaminants present in drilling mud were identified through 16S ribosomal deoxyribonucleic acid (rDNA) clone libraries and compared to species cultured from core samples. Together, these methods allowed us to categorize the recovered core samples according to the likelihood of contamination. Twenty-two of the 47 subcores that were retrieved were free of contamination by all the methods used and were subsequently used for microbiological culture and culture-independent analysis. Our approach provides a comprehensive assessment of both particulate and dissolved contaminants that could be applied to any environment with low biomass. ?? 2009 The Geological Society of America.

One-carbon (bio ?) Geochemistry in Subsurface Waters of the Serpentinizing Coast Range Ophiolite

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Mccollom, Tom; Schrenk, Matt; Cardace, Dawn

2011-01-01

Serpentinization - the aqueous alteration of ultramafic rocks - typically imparts a highly reducing and alkaline character to the reacting fluids. In turn, these can influence the speciation and potential for metabolism of one-carbon compounds in the system. We examined the aqueous geochemistry and assessed the biological potential of one-carbon compounds in the subsurface of the McLaughlin Natural Reserve (Coast Range Ophiolite, California, USA). Fluids from wells sunk at depths of 25-90 meters have pH values ranging from 9.7 to 11.5 and dissolved inorganic carbon (DIC concentrations) generally below 60 micromolar. Methane is present at concentrations up to 1.3 millimolar (approximately one-atmosphere saturation), and hydrogen concentrations are below 15 nanomolar, suggesting active consumption of H2 and production of CH4. However, methane production from CO2 is thermodynamically unfavorable under these conditions. Additionally, the speciation of DIC predominantly into carbonate at these high pH values creates a problem of carbon availability for any organisms that require CO2 (or bicarbonate) for catabolism or anabolism. A potential alternative is carbon monoxide, which is present in these waters at concentrations 2000-fold higher than equilibrium with atmospheric CO. CO is utilized in a variety of metabolisms, including methanogenesis, and bioavailability is not adversely affected by pH-dependent speciation (as for DIC). Methanogenesis from CO under in situ conditions is thermodynamically favorable and would satisfy biological energy requirements with respect to both Gibbs Energy yield and power.

Effects of 6 months of aging in water on hardness and surface roughness of two microhybrid dental composites.

PubMed

de Moraes, Rafael Ratto; Marimon, José Laurindo Machado; Schneider, Luis Felipe; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço; Bueno, Márcia

2008-06-01

This study assessed the effect of 6 months of aging in water on surface roughness and surface/subsurface hardness of two microhybrid resin composites. Filtek Z250 and Charisma were tested. Cylindrical specimens were obtained and stored in distilled water for 24 hours or 6 months, at 37 degrees C. For Knoop hardness evaluation, the specimens were transversely wet-flattened, and indentations were made on surface and subsurface layers. Data were submitted to three-way ANOVA and Tukey's test (alpha < or = 0.05). Surface roughness baseline measurements were made at 24 hours and repeated after 6 months of storage. Data were submitted to repeated measures ANOVA and Tukey's test (alpha < or = 0.05). Surface hardness (KHN, kg/mm(2)) means (+/- standard deviation) ranged from 55 +/- 1 to 49 +/- 4 for Z250 and from 50 +/- 2 to 41 +/- 3 for Charisma, at 24 hours and 6 months, respectively. Subsurface means ranged from 58 +/- 2 to 61 +/- 3 for Z250 and from 50 +/- 1 to 54 +/- 2 for Charisma, at 24 hours and 6 months. For both composites, the aged specimens presented significantly softer surfaces (p < 0.01). For the subsurface hardness, alteration after storage was detected only for Charisma, which presented a significant rise in hardness (p < 0.01). Z250 presented significantly harder surface and subsurface layers in comparison with Charisma. Surface roughness (Ra, mum) means ranged from 0.07 +/- 0.00 to 0.07 +/- 0.01 for Z250 and from 0.06 +/- 0.01 to 0.07 +/- 0.01 for Charisma, at 24 hours and 6 months, respectively. For both composites, no significant roughness alteration was detected during the study (p= 0.386). The 6-month period of storage in water presented a significant softening effect on the surfaces of the composites, although no significant deleterious alteration was detected for the subsurface hardness. In addition, the storage period had no significant effect on the surface roughness of the materials.

A Low-Cost, In Situ Resistivity and Temperature Monitoring System

EPA Science Inventory

We present a low-cost, reliable method for long-term in situ autonomous monitoring of subsurface resistivity and temperature in a shallow, moderately heterogeneous subsurface. Probes, to be left in situ, were constructed at relatively low cost with close electrode spacing. Once i...

A hydrogen-based subsurface microbial community dominated by methanogens

USGS Publications Warehouse

Chapelle, F.H.; O'Neil, Kyle; Bradley, P.M.; Methe, B.A.; Ciufo, S.A.; Knobel, L.L.; Lovley, D.R.

2002-01-01

The search for extraterrestrial life may be facilitated if ecosystems can be found on Earth that exist under conditions analogous to those present on other planets or moons. It has been proposed, on the basis of geochemical and thermodynamic considerations, that geologically derived hydrogen might support subsurface microbial communities on Mars and Europa in which methanogens form the base of the ecosystem1-5. Here we describe a unique subsurface microbial community in which hydrogen-consuming, methane-producing Archaea far outnumber the Bacteria. More than 90% of the 16s ribosomal DNA sequences recovered from hydrothermal waters circulating through deeply buried igneous rocks in Idaho are related to hydrogen-using methanogenic microorganisms. Geochemical characterization indicates that geothermal hydrogen, not organic carbon, is the primary energy source for this methanogen-dominated microbial community. These results demonstrate that hydrogen-based methanogenic communities do occur in Earth's subsurface, providing an analogue for possible subsurface microbial ecosystems on other planets.

Investigation of the sensitivity of a cross-polarized light visualization system to detect subclinical erythema and dryness in women with vulvovaginitis.

PubMed

Farage, Miranda A; Singh, Mukul; Ledger, William J

2009-07-01

An enhanced visualization technique using polarized light (Syris v600 enhanced visualization system; Syris Scientific LLC, Gray, ME) detects surface and subsurface ( approximately 1 mm depth) inflammation. We sought to compare the Syris v600 system with unaided visual inspection and colposcopy of the female genitalia. Erythema and dryness of the vulva, introitus, vagina, and cervix were visualized and scored by each method in patients with and without vulvitis. Subsurface visualization was more sensitive in detecting genital erythema and dryness at all sites whether or not symptoms were present. Subsurface inflammation of the introitus, vagina, and cervix only was detected uniquely in women with vulvar vestibulitis syndrome (VVS). A subset of women presenting with VVS exhibited subclinical inflammation of the vulva vestibule and vagina (designated VVS/lichen sclerosus subgroup). Enhanced visualization of the genital epithelial subsurface with cross-polarized light may assist in diagnosing subclinical inflammation in vulvar conditions heretofore characterized as sensory syndromes.

Reorientation of Sputnik Planitia implies a subsurface ocean on Pluto.

PubMed

Nimmo, F; Hamilton, D P; McKinnon, W B; Schenk, P M; Binzel, R P; Bierson, C J; Beyer, R A; Moore, J M; Stern, S A; Weaver, H A; Olkin, C B; Young, L A; Smith, K E

2016-12-01

The deep nitrogen-covered basin on Pluto, informally named Sputnik Planitia, is located very close to the longitude of Pluto's tidal axis and may be an impact feature, by analogy with other large basins in the Solar System. Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basin's present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography. Here we argue that if Sputnik Planitia did indeed form as a result of an impact and if Pluto possesses a subsurface ocean, the required positive gravity anomaly would naturally result because of shell thinning and ocean uplift, followed by later modest nitrogen deposition. Without a subsurface ocean, a positive gravity anomaly requires an implausibly thick nitrogen layer (exceeding 40 kilometres). To prolong the lifetime of such a subsurface ocean to the present day and to maintain ocean uplift, a rigid, conductive water-ice shell is required. Because nitrogen deposition is latitude-dependent, nitrogen loading and reorientation may have exhibited complex feedbacks.

Reorientation of Sputnik Planitia implies a subsurface ocean on Pluto

NASA Astrophysics Data System (ADS)

Nimmo, F.; Hamilton, D. P.; McKinnon, W. B.; Schenk, P. M.; Binzel, R. P.; Bierson, C. J.; Beyer, R. A.; Moore, J. M.; Stern, S. A.; Weaver, H. A.; Olkin, C. B.; Young, L. A.; Smith, K. E.; Moore, J. M.; McKinnon, W. B.; Spencer, J. R.; Beyer, R.; Binzel, R. P.; Buie, M.; Buratti, B.; Cheng, A.; Cruikshank, D.; Ore, C. Dalle; Earle, A.; Gladstone, R.; Grundy, W.; Howard, A. D.; Lauer, T.; Linscott, I.; Nimmo, F.; Parker, J.; Porter, S.; Reitsema, H.; Reuter, D.; Roberts, J. H.; Robbins, S.; Schenk, P. M.; Showalter, M.; Singer, K.; Strobel, D.; Summers, M.; Tyler, L.; White, O. L.; Umurhan, O. M.; Banks, M.; Barnouin, O.; Bray, V.; Carcich, B.; Chaikin, A.; Chavez, C.; Conrad, C.; Hamilton, D. P.; Howett, C.; Hofgartner, J.; Kammer, J.; Lisse, C.; Marcotte, A.; Parker, A.; Retherford, K.; Saina, M.; Runyon, K.; Schindhelm, E.; Stansberry, J.; Steffl, A.; Stryk, T.; Throop, H.; Tsang, C.; Verbiscer, A.; Winters, H.; Zangari, A.; Stern, S. A.; Weaver, H. A.; Olkin, C. B.; Young, L. A.; Smith, K. E.

2016-12-01

The deep nitrogen-covered basin on Pluto, informally named Sputnik Planitia, is located very close to the longitude of Pluto’s tidal axis and may be an impact feature, by analogy with other large basins in the Solar System. Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basin’s present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography. Here we argue that if Sputnik Planitia did indeed form as a result of an impact and if Pluto possesses a subsurface ocean, the required positive gravity anomaly would naturally result because of shell thinning and ocean uplift, followed by later modest nitrogen deposition. Without a subsurface ocean, a positive gravity anomaly requires an implausibly thick nitrogen layer (exceeding 40 kilometres). To prolong the lifetime of such a subsurface ocean to the present day and to maintain ocean uplift, a rigid, conductive water-ice shell is required. Because nitrogen deposition is latitude-dependent, nitrogen loading and reorientation may have exhibited complex feedbacks.

Identification of subsurface structures using electromagnetic data and shape priors

NASA Astrophysics Data System (ADS)

Tveit, Svenn; Bakr, Shaaban A.; Lien, Martha; Mannseth, Trond

2015-03-01

We consider the inverse problem of identifying large-scale subsurface structures using the controlled source electromagnetic method. To identify structures in the subsurface where the contrast in electric conductivity can be small, regularization is needed to bias the solution towards preserving structural information. We propose to combine two approaches for regularization of the inverse problem. In the first approach we utilize a model-based, reduced, composite representation of the electric conductivity that is highly flexible, even for a moderate number of degrees of freedom. With a low number of parameters, the inverse problem is efficiently solved using a standard, second-order gradient-based optimization algorithm. Further regularization is obtained using structural prior information, available, e.g., from interpreted seismic data. The reduced conductivity representation is suitable for incorporation of structural prior information. Such prior information cannot, however, be accurately modeled with a gaussian distribution. To alleviate this, we incorporate the structural information using shape priors. The shape prior technique requires the choice of kernel function, which is application dependent. We argue for using the conditionally positive definite kernel which is shown to have computational advantages over the commonly applied gaussian kernel for our problem. Numerical experiments on various test cases show that the methodology is able to identify fairly complex subsurface electric conductivity distributions while preserving structural prior information during the inversion.

An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints

PubMed Central

Willis, Matthew P.; Stevenson, Shawn M.; Pearl, Thomas P.; Mantooth, Brent A.

2014-01-01

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in understanding contaminant mass transport and the ability to decontaminate materials. If a material is contaminated, over time, the transport of highly toxic chemicals (such as chemical warfare agent species) out of the material can result in vapor exposure or transfer to the skin, which can result in percutaneous exposure to personnel who interact with the material. Due to the high toxicity of chemical warfare agents, the release of trace chemical quantities is of significant concern. Mapping subsurface concentration distribution and transport characteristics of absorbed agents enables exposure hazards to be assessed in untested conditions. Furthermore, these tools can be used to characterize subsurface reaction dynamics to ultimately design improved decontaminants or decontamination procedures. To achieve this goal, an inverse analysis mass transport modeling approach was developed that utilizes time-resolved mass spectroscopy measurements of vapor emission from contaminated paint coatings as the input parameter for calculation of subsurface concentration profiles. Details are provided on sample preparation, including contaminant and material handling, the application of mass spectrometry for the measurement of emitted contaminant vapor, and the implementation of inverse analysis using a physics-based diffusion model to determine transport properties of live chemical warfare agents including distilled mustard (HD) and the nerve agent VX. PMID:25226346

Enhanced truncated-correlation photothermal coherence tomography with application to deep subsurface defect imaging and 3-dimensional reconstructions

NASA Astrophysics Data System (ADS)

Tavakolian, Pantea; Sivagurunathan, Koneswaran; Mandelis, Andreas

2017-07-01

Photothermal diffusion-wave imaging is a promising technique for non-destructive evaluation and medical applications. Several diffusion-wave techniques have been developed to produce depth-resolved planar images of solids and to overcome imaging depth and image blurring limitations imposed by the physics of parabolic diffusion waves. Truncated-Correlation Photothermal Coherence Tomography (TC-PCT) is the most successful class of these methodologies to-date providing 3-D subsurface visualization with maximum depth penetration and high axial and lateral resolution. To extend the depth range and axial and lateral resolution, an in-depth analysis of TC-PCT, a novel imaging system with improved instrumentation, and an optimized reconstruction algorithm over the original TC-PCT technique is developed. Thermal waves produced by a laser chirped pulsed heat source in a finite thickness solid and the image reconstruction algorithm are investigated from the theoretical point of view. 3-D visualization of subsurface defects utilizing the new TC-PCT system is reported. The results demonstrate that this method is able to detect subsurface defects at the depth range of ˜4 mm in a steel sample, which exhibits dynamic range improvement by a factor of 2.6 compared to the original TC-PCT. This depth does not represent the upper limit of the enhanced TC-PCT. Lateral resolution in the steel sample was measured to be ˜31 μm.

TREATMENT OF HEXAVALENT CHROMIUM IN CHROMITE ORE PROCESSING SOLID WASTE USING A MIXED REDUCTANT SOLUTION OF FERROUS SULFATE AND SODIUM DITHIONITE

EPA Science Inventory

We developed a method for disseminating ferrous iron in the subsurface to enhance chemical reduction of hexavalent chromium (Cr(VI)) in a chromite ore processing solid waste derived from the production of ferrochrome alloy. The method utilizes ferrous sulfate (FeSO4) in combinati...

In situ sensors, weighing lysimeters and COSMOS under vegetated and bare conditions with subsurface drip irrigation

USDA-ARS?s Scientific Manuscript database

Long term weighing lysimeter records may have utility for assessment of climate changes occurring during the period of record. They typically enclose a depth of soil that exceeds the root zone of vegetation normally grown on them and have drainagy systems so that more or less natural hydrologic flux...

Grid vs Mesh: The case of Hyper-resolution Modeling in Urban Landscapes

NASA Astrophysics Data System (ADS)

Grimley, L. E.; Tijerina, D.; Khanam, M.; Tiernan, E. D.; Frazier, N.; Ogden, F. L.; Steinke, R. C.; Maxwell, R. M.; Cohen, S.

2017-12-01

In this study, the relative performance of ADHydro and GSSHA was analyzed for a small and large rainfall event in an urban watershed called Dead Run near Baltimore, Maryland. ADHydro is a physics-based, distributed, hydrologic model that uses an unstructured mesh and operates in a high performance computing environment. The Gridded Surface/Subsurface Hydrological Analysis (GSSHA) model, which is maintained by the US Army Corps of Engineers, is a physics-based, distributed, hydrologic model that incorporates subsurface utilities and uses a structured mesh. A large portion of the work served as alpha-testing of ADHydro, which is under development by the CI-WATER modeling team at the University of Wyoming. Triangular meshes at variable resolutions were created to assess the sensitivity of ADHydro to changes in resolution and test the model's ability to handle a complicated urban routing network with structures present. ADHydro was compared with GSSHA which does not have the flexibility of an unstructured grid but does incorporate the storm drainage network. The modelled runoff hydrographs were compared to observed United States Geological Survey (USGS) stream gage data. The objective of this study was to analyze the effects of mesh type and resolution using ADHydro and GSSHA in simulations of an urban watershed.

Optimal Environmental Conditions and Anomalous Ecosystem Responses: Constraining Bottom-up Controls of Phytoplankton Biomass in the California Current System

PubMed Central

Jacox, Michael G.; Hazen, Elliott L.; Bograd, Steven J.

2016-01-01

In Eastern Boundary Current systems, wind-driven upwelling drives nutrient-rich water to the ocean surface, making these regions among the most productive on Earth. Regulation of productivity by changing wind and/or nutrient conditions can dramatically impact ecosystem functioning, though the mechanisms are not well understood beyond broad-scale relationships. Here, we explore bottom-up controls during the California Current System (CCS) upwelling season by quantifying the dependence of phytoplankton biomass (as indicated by satellite chlorophyll estimates) on two key environmental parameters: subsurface nitrate concentration and surface wind stress. In general, moderate winds and high nitrate concentrations yield maximal biomass near shore, while offshore biomass is positively correlated with subsurface nitrate concentration. However, due to nonlinear interactions between the influences of wind and nitrate, bottom-up control of phytoplankton cannot be described by either one alone, nor by a combined metric such as nitrate flux. We quantify optimal environmental conditions for phytoplankton, defined as the wind/nitrate space that maximizes chlorophyll concentration, and present a framework for evaluating ecosystem change relative to environmental drivers. The utility of this framework is demonstrated by (i) elucidating anomalous CCS responses in 1998–1999, 2002, and 2005, and (ii) providing a basis for assessing potential biological impacts of projected climate change. PMID:27278260

A Miniaturized Spectrometer for Optimized Selection of Subsurface Samples for Future MSR Missions

NASA Astrophysics Data System (ADS)

De Sanctis, M. C.; Altieri, F.; De Angelis, S.; Ferrari, M.; Frigeri, A.; Biondi, D.; Novi, S.; Antonacci, F.; Gabrieli, R.; Paolinetti, R.; Villa, F.; Ammannito, A.; Mugnuolo, R.; Pirrotta, S.

2018-04-01

We present the concept of a miniaturized spectrometer based on the ExoMars2020/Ma_MISS experiment. Coupled with a drill tool, it will allow an assessment of subsurface composition and optimize the selection of martian samples with a high astrobiological potential.

KINETIC CONTROL OF OXIDATION STATE AT THERMODYNAMICALLY BUFFERED POTENTIALS IN SUBSURFACE WATERS

EPA Science Inventory

Dissolved oxygen (DO) and organic carbon (Corg) are among the highest- and lowest-potential reactants, respectively, of redox couples in natural waters. When DO and Corg are present in subsurface settings, other couples are drawn toward potentials imposed by them, generating a b...

Mechanical properties and molecular structure analysis of subsurface dentin after Er:YAG laser irradiation.

PubMed

He, Zhengdi; Chen, Lingling; Hu, Xuejuan; Shimada, Yasushi; Otsuki, Masayuki; Tagami, Junji; Ruan, Shuangchen

2017-10-01

The purpose of this study was to evaluate the chemical and mechanical modifications in subsurface dentin layer after Er: YAG (Erbium-Yttrium Aluminium Garnet) laser irradiation, as the guidance of new dental restorative materials specific for laser irradiated dentin. Dentin disks obtained from extracted human molars were prepared and exposed to a single pulse Er:YAG laser irradiation at 80mJ/pulse. After laser irradiation the mechanical and chemical characteristics of intertubular dentin in subsurface layer were studied using nanoindentation tester and micro-Raman spectromy (μ-RS). The dentin 5-50µm depth beneath the lased surface was determined as testing area. Two-way analysis of variance (ANOVA) were used to compare the mechanical values between lased and untreated subsurface dentin (P = 0.05). A laser affected subsurface dentin layer after Er:YAG laser treatment is present. The laser irradiation is considered to decrease the mechanical properties in the superficial subsurface layer (<15µm deep). There was no significant difference in nanohardness and Young's modulus between lased subsurface dentin and untreated dentin (p > 0.05) under the depth of 15µm. However, the dentin at 5µm and 10µm depth beneath the lased surface exhibited significantly lower (~ 47.8% and ~ 33.6% respectively) hardness (p < 0.05). Er:YAG laser irradiation affected both mineral and organic components in subsurface dentin layer, a higher degree of crystallinity and reduced organic compounds occurred in the lased subsurface dentin. Under the tested laser parameters, Er:YAG laser irradiation causes lower mechanical values and reduction of organic components in subsurface dentin, which has deleterious effects on resin adhesion to this area. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Feeding a subsurface biosphere: radiolysis and abiogenic energy sources

NASA Astrophysics Data System (ADS)

Onstott, T.

Noble gas analyses of ground water collected from the deep, fractured, basaltic andesite and quartzite Archean strata in South Africa suggest subsurface residence times ranging from tens to hundreds of millions of years. Hydraulically isolated compartments of highly saline water contain hundreds of μM concentrations of gas comprised primarily of C1-4 hydrocarbons, H2 and He, with minor Ar and N .2 Carbon and hydrogen isotopic analyses of the hydrocarbons suggest an abiogenic origin com atible with surface catalysed reductive assimilation (i.e. Fischer-Tropschp synthesis). H2 and He data suggest that the H2 is generated by subsurface radiolysis of water. One sample of a saline, isolated water/gas pocket agrees exactly with that predicted by radioactive decay of U, Th, K in the host rock and indicates a subsurface H2 production rate of 0.1 to 1 nM/yr. Other samples yielded less H2 than predicted and require a sink for this H2 . Possible sinks include microbial H2 oxidation and abiotic formation of hydrocarbons at rates slightly less than the H2 production rate. Highly diffusive H2 is essential for life in deep subsurface environments where only trace amounts of organic carbon exist. Lithoautotrophic microbes can acquire energy from the redox reactions involving H2 with other electron acceptors (Fe3 +, SO4 2 - or CO2 ), to synthesis organic carbon and can be fully independent of solar-driven photosynthesis. The microbial abundance in many of these ground water samples, however, is below our detection limit (<5000 cells/ml). This contrasts with shallow sedimentary aquifers where H2 levels of tens of nM are regulated by the coexistence of autotrophs/lithotrophs and heterotrophs for maximum efficiency of H2 utilization. The excessive H2 found in deep crustal environments implies that these microbial ecosystems are electron-acceptor and or substrate limited. The oxidants generated by water radiolysis interact with the reduced solid phases in the rock matrix, e.g. pyrite, producing potential electron acceptors, e.g. Fe3 +, that may be readily available for consumption by microbial communities than H . Nitrogen doesn't appear to be2 limited, because ammonia concentrations range upwards to tens of μM, but its origin remains a mystery. The unused H2 , CH4 and He continue to migrate upward to shallow aquifers. Microbial H2 oxidation may dominate over Fischer-Tropsch reactions in crustal environments where formation temperatures are <120o C; and vice versa for deeper crustal environments. This H2 cycle should be present on extraterrestrial bodies, producing potential chemical energy and crustal scale diffusive fluxes from the interaction subsurface ice/water and radiogenic decay.

Reconstructing a hydrogen-driven microbial metabolic network in Opalinus Clay rock

DOE PAGES

Bagnoud, Alexandre; Chourey, Karuna; Hettich, Robert L.; ...

2016-10-14

A significant fraction (~ 20%) of microbial life is found in the terrestrial deep subsurface, yet the metabolic processes extant in those environments are poorly understood. Here we show that H 2, injected into the Opalinus Clay formation in a borehole located 300 meters below the surface, fuels a community of microorganisms with interconnected metabolisms. Metagenomic binning and metaproteomic analysis reveal a complete carbon cycle, driven by autotrophic hydrogen oxidizers. Dead biomass from these organisms is a substrate for a fermenting bacterium that produces acetate as a product. In turn, complete oxidizer heterotrophic sulfate- reducing bacteria utilize acetate and oxidizemore » it to CO 2, closing the cycle. This metabolic reconstruction sheds light onto a hydrogen-driven carbon cycle, and a sunlight-independent ecosystem in the deep subsurface.« less

Evolving hydrologic connectivity in discontinuous permafrost lowlands: what it means for lake systems

NASA Astrophysics Data System (ADS)

Walvoord, M. A.; Jepsen, S. M.; Rover, J.; Voss, C. I.; Briggs, M. A.

2015-12-01

Permafrost influence on the hydrologic connectivity of surface water bodies in high-latitude lowlands is complicated by subsurface heterogeneity and the propensity of the system to change over time. In general, permafrost limits the subsurface exchange of water, solute, and nutrients between lakes and rivers. It follows that permafrost thaw could enhance subsurface hydrologic connectivity among surface water bodies, but the impact of this process on lake distribution is not well known. Changes in the extent of lakes in interior Alaska have important ecological and societal impacts since lakes provide (1) critical habitat for migratory arctic shorebirds and waterfowl, fish, and wildlife, and (2) provisional, recreational, and cultural resources for local communities. We utilize electromagnetic imaging of the shallow subsurface and remote sensing of lake level dynamics in the Yukon Flats of interior Alaska, USA, together with water balance modeling, to gain insight into the influence of discontinuous permafrost on lowland lake systems. In the study region with relatively low precipitation, observations suggest that lakes that are hydrologically isolated during normal conditions are sustained by periodic river flooding events, including ice-jam floods that occur during river ice break-up. Climatically-influenced alterations in flooding frequency and intensity, as well as depth to permafrost, are quantitatively assessed in the context of lake maintenance. Scenario modeling is used to evaluate lake level evolution under plausible changing conditions. Model results demonstrate how permafrost degradation can reduce the dependence of typical lowland lakes on flooding events. Study results also suggest that river flooding may recharge a more spatially widespread zone of lakes and wetlands under future scenarios of permafrost table deepening and enhanced subsurface hydrologic connectivity.

Imaging Preferential Flow Pathways of Contaminants from Passive Acid Mine Drainage Mitigation Sites Using Electrical Resistivity

NASA Astrophysics Data System (ADS)

Kelley, N.; Mount, G.; Terry, N.; Herndon, E.; Singer, D. M.

2017-12-01

The Critical Zone represents the surficial and shallow layer of rock, air, water, and soil where most interactions between living organisms and the Earth occur. Acid mine drainage (AMD) resulting from coal extraction can influence both biological and geochemical processes across this zone. Conservative estimates suggest that more than 300 million gallons of AMD are released daily, making this acidic solution of water and contaminants a common issue in areas with legacy or current coal extraction. Electrical resistivity imaging (ERI) provides a rapid and minimally invasive method to identify and monitor contaminant pathways from AMD remediation systems in the subsurface of the Critical Zone. The technique yields spatially continuous data of subsurface resistivity that can be inverted to determine electrical conductivity as a function of depth. Since elevated concentrations of heavy metals can directly influence soil conductivity, ERI data can be used to trace the flow pathways or perhaps unknown mine conduits and transport of heavy metals through the subsurface near acid mine drainage sources. This study aims to examine preferential contaminant migration from those sources through substrate pores, fractures, and shallow mine workings in the near subsurface surrounding AMD sites in eastern Ohio and western Pennsylvania. We utilize time lapse ERI measures during different hydrologic conditions to better understand the variability of preferential flow pathways in relation to changes in stage and discharge within the remediation systems. To confirm ERI findings, and provide constraint to geochemical reactions occurring in the shallow subsurface, we conducted Inductively Coupled Plasma (ICP) spectrometry analysis of groundwater samples from boreholes along the survey transects. Through these combined methods, we can provide insight into the ability of engineered systems to contain and isolate metals in passive acid mine drainage treatment systems.

SUBSURFACE PROPERTY RIGHTS: IMPLICATIONS FOR GEOLOGIC CO2 SEQUESTRATION (PRESENTATION)

EPA Science Inventory

The paper discusses subsurface property rights as they apply to geologic sequestration (GS) of carbon dioxide (CO2). GS projects inject captured CO2 into deep (greater than ~1 km) geologic formations for the explicit purpose of avoiding atmospheric emission of CO2. Because of the...

3DHYDROGEOCHEM: A 3-DIMENSIONAL MODEL OF DENSITY-DEPENDENT SUBSURFACE FLOW AND THERMAL MULTISPECIES-MULTICOMPONENT HYDROGEOCHEMICAL TRANSPORT

EPA Science Inventory

This report presents a three-dimensional finite-element numerical model designed to simulate chemical transport in subsurface systems with temperature effect taken into account. The three-dimensional model is developed to provide (1) a tool of application, with which one is able...

ADAPTATION OF SUBSURFACE MICROBIAL BIOFILM COMMUNITIES IN RESPONSE TO CHEMICAL STRESSORS

EPA Science Inventory

The impact of this work will help improve our understanding of how subsurface biofilm communities respond to chemical stressors that are likely to be present at hazardous waste sites. Ultimately, these results can be used to determine more effective ways to insure proper envir...

40 CFR 264.221 - Design and operating requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... subsurface soil or ground water or surface water at any time during the active life (including the closure... into the liner (but not into the adjacent subsurface soil or ground water or surface water) during the... the attenuative capacity and thickness of the liners and soils present between the impoundment and...

40 CFR 264.221 - Design and operating requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... subsurface soil or ground water or surface water at any time during the active life (including the closure... into the liner (but not into the adjacent subsurface soil or ground water or surface water) during the... the attenuative capacity and thickness of the liners and soils present between the impoundment and...

40 CFR 264.221 - Design and operating requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... subsurface soil or ground water or surface water at any time during the active life (including the closure... into the liner (but not into the adjacent subsurface soil or ground water or surface water) during the... the attenuative capacity and thickness of the liners and soils present between the impoundment and...

The WISDOM Radar: Unveiling the Subsurface Beneath the ExoMars Rover and Identifying the Best Locations for Drilling

NASA Astrophysics Data System (ADS)

Ciarletti, Valérie; Clifford, Stephen; Plettemeier, Dirk; Le Gall, Alice; Hervé, Yann; Dorizon, Sophie; Quantin-Nataf, Cathy; Benedix, Wolf-Stefan; Schwenzer, Susanne; Pettinelli, Elena; Heggy, Essam; Herique, Alain; Berthelier, Jean-Jacques; Kofman, Wlodek; Vago, Jorge L.; Hamran, Svein-Erik; WISDOM Team

2017-07-01

The search for evidence of past or present life on Mars is the principal objective of the 2020 ESA-Roscosmos ExoMars Rover mission. If such evidence is to be found anywhere, it will most likely be in the subsurface, where organic molecules are shielded from the destructive effects of ionizing radiation and atmospheric oxidants. For this reason, the ExoMars Rover mission has been optimized to investigate the subsurface to identify, understand, and sample those locations where conditions for the preservation of evidence of past life are most likely to be found. The Water Ice Subsurface Deposit Observation on Mars (WISDOM) ground-penetrating radar has been designed to provide information about the nature of the shallow subsurface over depth ranging from 3 to 10 m (with a vertical resolution of up to 3 cm), depending on the dielectric properties of the regolith. This depth range is critical to understanding the geologic evolution stratigraphy and distribution and state of subsurface H2O, which provide important clues in the search for life and the identification of optimal drilling sites for investigation and sampling by the Rover's 2-m drill. WISDOM will help ensure the safety and success of drilling operations by identification of potential hazards that might interfere with retrieval of subsurface samples.

Holographic Subsurface Radar Technique for Nondestructive Testing of Dielectric Structures

NASA Astrophysics Data System (ADS)

Ivashov, S. I.; Bugaev, A. S.; Zhuravlev, A. V.; Razevig, V. V.; Chizh, M. A.; Ivashov, A. I.

2018-02-01

Holographic subsurface radar method is compared with the conventional technology of impulse radars. Basic relationships needed for the reconstruction of complex microwave holograms are presented. Possible applications of the proposed technology are discussed. Diagnostics of polyurethane foam coatings of spacecrafts is used as an example of the efficiency of holographic subsurface radars. Results of reconstruction of complex and amplitude microwave holograms are compared. It is demonstrated that the image quality that results from reconstruction of complex microwave holograms is higher than the image quality obtained with the aid of amplitude holograms.

Large-scale assessment of present day and future groundwater recharge and its sensitivity to climate variability in Europe's karst regions

NASA Astrophysics Data System (ADS)

Hartmann, A. J.; Gleeson, T. P.; Wagener, T.; Wada, Y.

2016-12-01

Karst aquifers in Europe are an important source of fresh water contributing up to half of the total drinking water supply in some countries. Karstic groundwater recharge is one of the most important components of the water balance of karst systems as it feeds the karst aquifers. Presently available large-scale hydrological models do not consider karst heterogeneity adequately. Projections of current and potential future groundwater recharge of Europe's karst aquifers are therefore unclear. In this study we compare simulations of present (1991-2010) and future (2080-2099) recharge using two different models to simulate groundwater recharge processes. One model includes karst processes (subsurface heterogeneity, lateral flow and concentrated recharge), while the other is based on the conceptual understanding of common hydrological systems (homogeneous subsurface, saturation excess overland flow). Both models are driven by the bias-corrected 5 GCMs of the ISI-MIP project (RCP8.5). To further assess sensitivity of groundwater recharge to climate variability, we calculate the elasticity of recharge rates to annual precipitation, temperature and average intensity of rainfall events, which is the median change of recharge that corresponds to the median change of these climate variables within the present and future time period, respectively. Our model comparison shows that karst regions over Europe have enhanced recharge rates with greater inter-annual variability compared to those with more homogenous subsurface properties. Furthermore, the heterogeneous representation shows stronger elasticity concerning climate variability than the homogeneous subsurface representation. This difference tends to increase towards the future. Our results suggest that water management in regions with heterogeneous subsurface can expect a higher water availability than estimated by most of the current large-scale simulations, while measures should be taken to prepare for increasingly variable groundwater recharge rates.

SUBSURFACE RESIDENCE TIMES AS AN ALGORITHM FOR AQUIFER SENSITIVITY MAPPING: TESTING THE CONCEPT WITH ANALYTIC ELEMENT GROUND WATER MODELS IN THE CONTENTNEA CREEK BASIN, NORTH CAROLINA, USA

EPA Science Inventory

The objective of this research is to test the utility of simple functions of spatially integrated and temporally averaged ground water residence times in shallow "groundwatersheds" with field observations and more detailed computer simulations. The residence time of water in the...

Effects of Sediment Microfabric on Benthic Optical Properties

DTIC Science & Technology

2003-09-30

wavelengths. Pigment A is phycoerythrin, B is phycocyanin , and C is chlorophyll a. The large decrease in irradiance at ~750 nm is likely an...Deconvolution methods were utilized to identify a variety of pigments (chlorophyll b and c, phycoerythrin, phycocyanin , fucoxanthin, peridinin, and...for subsurface mapping of phytobenthic communities. Efforts were also focused on preparation of manuscripts for publication. 4 IMPACT/ APPLICATION

Respiratory interactions of soil bacteria with (semi)conductive iron-oxide minerals.

PubMed

Kato, Souichiro; Nakamura, Ryuhei; Kai, Fumiyoshi; Watanabe, Kazuya; Hashimoto, Kazuhito

2010-12-01

Pure-culture studies have shown that dissimilatory metal-reducing bacteria are able to utilize iron-oxide nanoparticles as electron conduits for reducing distant terminal acceptors; however, the ecological relevance of such energy metabolism is poorly understood. Here, soil microbial communities were grown in electrochemical cells with acetate as the electron donor and electrodes (poised at 0.2 V versus Ag/AgCl) as the electron acceptors in the presence and absence of iron-oxide nanoparticles, and respiratory current generation and community structures were analysed. Irrespective of the iron-oxide species (hematite, magnetite or ferrihydrite), the supplementation with iron-oxide minerals resulted in large increases (over 30-fold) in current, while only a moderate increase (∼10-fold) was observed in the presence of soluble ferric/ferrous irons. During the current generation, insulative ferrihydrite was transformed into semiconductive goethite. Clone-library analyses of 16S rRNA gene fragments PCR-amplified from the soil microbial communities revealed that iron-oxide supplementation facilitated the occurrence of Geobacter species affiliated with subsurface clades 1 and 2. We suggest that subsurface-clade Geobacter species preferentially thrive in soil by utilizing (semi)conductive iron oxides for their respiration. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

Characterization of Two Subsurface H2-Utilizing Bacteria, Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov., and Their Ecological Roles

PubMed Central

Krumholz, Lee R.; Harris, Steve H.; Tay, Stephen T.; Suflita, Joseph M.

1999-01-01

We examined the relative roles of acetogenic and sulfate-reducing bacteria in H2 consumption in a previously characterized subsurface sandstone ecosystem. Enrichment cultures originally inoculated with ground sandstone material obtained from a Cretaceous formation in central New Mexico were grown with hydrogen in a mineral medium supplemented with 0.02% yeast extract. Sulfate reduction and acetogenesis occurred in these cultures, and the two most abundant organisms carrying out the reactions were isolated. Based on 16S rRNA analysis data and on substrate utilization patterns, these organisms were named Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov. The steady-state H2 concentrations measured in sandstone-sediment slurries (threshold concentration, 5 nM), in pure cultures of sulfate reducers (threshold concentration, 2 nM), and in pure cultures of acetogens (threshold concentrations 195 to 414 nM) suggest that sulfate reduction is the dominant terminal electron-accepting process in the ecosystem examined. In an experiment in which direct competition for H2 between D. hypogeium and A. psammolithicum was examined, sulfate reduction was the dominant process. PMID:10347005

Modeling subsurface stormflow initiation in low-relief landscapes

NASA Astrophysics Data System (ADS)

Hopp, Luisa; Vaché, Kellie B.; Rhett Jackson, C.; McDonnell, Jeffrey J.

2015-04-01

Shallow lateral subsurface flow as a runoff generating mechanism at the hillslope scale has mostly been studied in steeper terrain with typical hillside angles of 10 - 45 degrees. These studies have shown that subsurface stormflow is often initiated at the interface between a permeable upper soil layer and a lower conductivity impeding layer, e.g. a B horizon or bedrock. Many studies have identified thresholds of event size and soil moisture states that need to be exceeded before subsurface stormflow is initiated. However, subsurface stormflow generation on low-relief hillslopes has been much less studied. Here we present a modeling study that investigates the initiation of subsurface stormflow on low-relief hillslopes in the Upper Coastal Plain of South Carolina, USA. Hillslopes in this region typically have slope angles of 2-5 degrees. Topsoils are sandy, underlain by a low-conductivity sandy clay loam Bt horizon. Subsurface stormflow has only been intercepted occasionally in a 120 m long trench, and often subsurface flow was not well correlated with stream signals, suggesting a disconnect between subsurface flow on the hillslopes and stream flow. We therefore used a hydrologic model to better understand which conditions promote the initiation of subsurface flow in this landscape, addressing following questions: Is there a threshold event size and soil moisture state for producing lateral subsurface flow? What role does the spatial pattern of depth to the impeding clay layer play for subsurface stormflow dynamics? We reproduced a section of a hillslope, for which high-resolution topographic data and depth to clay measurements were available, in the hydrologic model HYDRUS-3D. Soil hydraulic parameters were based on experimentally-derived data. The threshold analysis was first performed using hourly climate data records for 2009-2010 from the study site to drive the simulation. For this period also trench measurements of subsurface flow were available. In addition, we also ran a longer-term simulation, using daily climate data for a nine year period to include more variable climate conditions in the threshold analysis. The model captured the observed subsurface flow instances very well. The threshold analysis indicated that the occurrence of subsurface stormflow uncommon, with a large proportion of the water perching above the clay layer percolating vertically into the clay layer. Event sizes of approximately 70-80 mm were required for initiating subsurface stormflow. The hourly data from 2009-2010 was subsequently used to test if the actual spatial distribution of depth to clay is a major control for the occurrence and magnitude of lateral subsurface flow. Results suggest that in this low-relief landscape also a spatially uniform mean depth to clay reproduces well the hydrologic behavior.

Electrode Cultivation and Interfacial Electron Transport in Subsurface Microorganisms

NASA Astrophysics Data System (ADS)

Karbelkar, A. A.; Jangir, Y.; Reese, B. K.; Wanger, G.; Anderson, C.; El-Naggar, M.; Amend, J.

2016-12-01

Continental subsurface environments can present significant energetic challenges to the resident microorganisms. While these environments are geologically diverse, potentially allowing energy harvesting by microorganisms that catalyze redox reactions, many of the abundant electron donors and acceptors are insoluble and therefore not directly bioavailable. Microbes can use extracellular electron transfer (EET) as a metabolic strategy to interact with redox active surfaces. This process can be mimicked on electrode surfaces and hence can lead to enrichment and quantification of subsurface microorganisms A primary bioelectrochemical enrichment with different oxidizing and reducing potentials set up in a single bioreactor was applied in situ to subsurface microorganisms residing in iron oxide rich deposits in the Sanford Underground Research Facility. Secondary enrichment revealed a plethora of classified and unclassified subsurface microbiota on both oxidizing and reducing potentials. From this enrichment, we have isolated a Gram-positive Bacillus along with Gram-negative Cupriavidus and Anaerospora strains (as electrode reducers) and Comamonas (as an electrode oxidizer). The Bacillus and Comamonas isolates were subjected to a detailed electrochemical characterization in half-reactors at anodic and cathodic potentials, respectively. An increase in cathodic current upon inoculation and cyclic voltammetry measurements confirm the hypothesis that Comamonas is capable of electron uptake from electrodes. In addition, measurements of Bacillus on anodes hint towards novel mechanisms that allow EET from Gram-positive bacteria. This study suggests that electrochemical approaches are well positioned to dissect such extracellular interactions that may be prevalent in the subsurface, while using physical electrodes to emulate the microhabitats, redox and geochemical gradients, and the spatially dependent interspecies interactions encountered in the subsurface. Electrochemical characterization of isolated strains can help us establish the possible mechanisms of EET, and hence provide an insight on survival strategies of subsurface microbiota in extreme environments. Continental subsurface environments can present significant energetic challenges to the resident microorganisms. While these environments are geologically diverse, potentially allowing energy harvesting by microorganisms that catalyze redox reactions, many of the abundant electron donors and acceptors are insoluble and therefore not directly bioavailable. Microbes can use extracellular electron transfer (EET) as a metabolic strategy to interact with redox active surfaces. This process can be mimicked on electrode surfaces and hence can lead to enrichment and quantification of subsurface microorganisms A primary bioelectrochemical enrichment with different oxidizing and reducing potentials set up in a single bioreactor was applied in situ to subsurface microorganisms residing in iron oxide rich deposits in the Sanford Underground Research Facility. Secondary enrichment revealed a plethora of classified and unclassified subsurface microbiota on both oxidizing and reducing potentials. From this enrichment, we have isolated a Gram-positive Bacillus along with Gram-negative Cupriavidus and Anaerospora strains (as electrode reducers) and Comamonas (as an electrode oxidizer). The Bacillus and Comamonas isolates were subjected to a detailed electrochemical characterization in half-reactors at anodic and cathodic potentials, respectively. An increase in cathodic current upon inoculation and cyclic voltammetry measurements confirm the hypothesis that Comamonas is capable of electron uptake from electrodes. In addition, measurements of Bacillus on anodes hint towards novel mechanisms that allow EET from Gram-positive bacteria. This study suggests that electrochemical approaches are well positioned to dissect such extracellular interactions that may be prevalent in the subsurface, while using physical electrodes to emulate the microhabitats, redox and geochemical gradients, and the spatially dependent interspecies interactions encountered in the subsurface. Electrochemical characterization of isolated strains can help us establish the possible mechanisms of EET, and hence provide an insight on survival strategies of subsurface microbiota in extreme environments.

Microbial Community Shifts due to Hydrofracking: Observations from Field-Scale Observations and Laboratory-Scale Incubations

NASA Astrophysics Data System (ADS)

Mouser, P. J.; Ansari, M.; Hartsock, A.; Lui, S.; Lenhart, J.

2012-12-01

The use of fluids containing chemicals and variable water sources during the hydrofracking of unconventional shale is the source of considerable controversy due to perceived risks from altered subsurface biogeochemistry and the potential for contaminating potable water supplies. Rapid shifts in subsurface biogeochemistry are often driven by available macronutrients combined with the abundance and metabolic condition of the subsurface microbiota. While the depth that fracturing occurs in the Marcellus formation is reasonably deep to pose little risk to groundwater supplies, no published studies have systematically characterized the indigenous microbial population and how this community is altered through variable fluid management practices (e.g., chemical composition, source water makeup). In addition, limited information is available on how shallower microbial communities and geochemical conditions might be affected through the accidental release of these fluids to groundwater aquifers. Our measurements indicate field-applied and laboratory-generated fracking fluids contain levels of organic carbon greater than 300 mg/l and nitrogen concentrations greater than 80 mg/l that may differentially stimulate microbial growth in subsurface formations. In contrast to certain inorganic constituents (e.g., chloride) which increase in concentration through the flowback period; dissolved organic carbon levels decrease with time after the fracturing process through multiple attenuation processes (dilution, sorption, microbial utilization). Pyrosequencing data of the 16S rRNA gene indicate a shift from a more diverse source water microbial community to a less diverse community typical of a brine formation as time after fracturing increases. The introduction of varying percentages of a laboratory-generated fracking fluid to microcosm bottles containing groundwater and aquifer media stimulated biogeochemical changes similar to the introduction of landfill leachate, another wastewater containing elevated carbon, nitrogen, and complex organic constituents (e.g., decreased redox conditions, stepwise utilization of available terminal electron acceptors, enriched Fe(II) and sulfide concentrations). These research findings are important for understanding how fluids used during shale energy development may alter in situ microbial communities and provide insight into processes that attenuate the migration of these fluids in shallow aquifers and deep shale formations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sentis, Manuel Lorenzo; Gable, Carl W.

Furthermore, there are many applications in science and engineering modeling where an accurate representation of a complex model geometry in the form of a mesh is important. In applications of flow and transport in subsurface porous media, this is manifest in models that must capture complex geologic stratigraphy, structure (faults, folds, erosion, deposition) and infrastructure (tunnels, boreholes, excavations). Model setup, defined as the activities of geometry definition, mesh generation (creation, optimization, modification, refine, de-refine, smooth), assigning material properties, initial conditions and boundary conditions requires specialized software tools to automate and streamline the process. In addition, some model setup tools willmore » provide more utility if they are designed to interface with and meet the needs of a particular flow and transport software suite. A control volume discretization that uses a two point flux approximation is for example most accurate when the underlying control volumes are 2D or 3D Voronoi tessellations. In this paper we will present the coupling of LaGriT, a mesh generation and model setup software suite and TOUGH2 to model subsurface flow problems and we show an example of how LaGriT can be used as a model setup tool for the generation of a Voronoi mesh for the simulation program TOUGH2. To generate the MESH file for TOUGH2 from the LaGriT output a standalone module Lagrit2Tough2 was developed, which is presented here and will be included in a future release of LaGriT. Here in this paper an alternative method to generate a Voronoi mesh for TOUGH2 with LaGriT is presented and thanks to the modular and command based structure of LaGriT this method is well suited to generating a mesh for complex models.« less

Interpretation of Ground Temperature Anomalies in Hydrothermal Discharge Areas

NASA Astrophysics Data System (ADS)

Price, A. N.; Lindsey, C.; Fairley, J. P., Jr.

2017-12-01

Researchers have long noted the potential for shallow hydrothermal fluids to perturb near-surface temperatures. Several investigators have made qualitative or semi-quantitative use of elevated surface temperatures; for example, in snowfall calorimetry, or for tracing subsurface flow paths. However, little effort has been expended to develop a quantitative framework connecting surface temperature observations with conditions in the subsurface. Here, we examine an area of shallow subsurface flow at Burgdorf Hot Springs, in the Payette National Forest, north of McCall, Idaho USA. We present a simple analytical model that uses easily-measured surface data to infer the temperatures of laterally-migrating shallow hydrothermal fluids. The model is calibrated using shallow ground temperature measurements and overburden thickness estimates from seismic refraction studies. The model predicts conditions in the shallow subsurface, and suggests that the Biot number may place a more important control on the expression of near-surface thermal perturbations than previously thought. In addition, our model may have application in inferring difficult-to-measure parameters, such as shallow subsurface discharge from hydrothermal springs.

Fibre optic confocal imaging (FOCI) for subsurface microscopy of the colon in vivo.

PubMed Central

Delaney, P M; King, R G; Lambert, J R; Harris, M R

1994-01-01

Fibre optic confocal imaging (FOCI) is a new type of microscopy which has been recently developed (Delaney et al. 1993). In contrast to conventional light microscopy, FOCI and other confocal techniques allow clear imaging of subsurface structures within translucent objects. However, unlike conventional confocal microscopes which are bulky (because of a need for accurate alignment of large components) FOCI allows the imaging end to be miniaturised and relatively mobile. FOCI is thus particularly suited for clear subsurface imaging of structures within living animals or subjects. The aim of the present study was to assess the suitability of using FOCI for imaging of subsurface structures within the colon, both in vitro (human and rat biopsies) and in vivo (in rats). Images were obtained in fluorescence mode (excitation 488 nm, detection above 515 nm) following topical application of fluorescein. By this technique the glandular structure of the colon was imaged. FOCI is thus suitable for subsurface imaging of the colon in vivo. Images Fig. 2 Fig. 3 PMID:8157487

Reactive transport codes for subsurface environmental simulation

DOE PAGES

Steefel, C. I.; Appelo, C. A. J.; Arora, B.; ...

2014-09-26

A general description of the mathematical and numerical formulations used in modern numerical reactive transport codes relevant for subsurface environmental simulations is presented. The formulations are followed by short descriptions of commonly used and available subsurface simulators that consider continuum representations of flow, transport, and reactions in porous media. These formulations are applicable to most of the subsurface environmental benchmark problems included in this special issue. The list of codes described briefly here includes PHREEQC, HPx, PHT3D, OpenGeoSys (OGS), HYTEC, ORCHESTRA, TOUGHREACT, eSTOMP, HYDROGEOCHEM, CrunchFlow, MIN3P, and PFLOTRAN. The descriptions include a high-level list of capabilities for each of themore » codes, along with a selective list of applications that highlight their capabilities and historical development.« less

Surface and subsurface inspection of food safety and quality using a line-scan Raman system

USDA-ARS?s Scientific Manuscript database

This paper presents a line-scan Raman platform for food safety and quality research, which can be configured for Raman chemical imaging (RCI) mode for surface inspection and spatially offset Raman spectroscopy (SORS) mode for subsurface inspection. In the RCI mode, macro-scale imaging was achieved u...

40 CFR 264.251 - Design and operating requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... any migration of wastes out of the pile into the adjacent subsurface soil or ground water or surface... adjacent subsurface soil or ground water or surface water) during the active life of the facility. The... attenuative capacity and thickness of the liners and soils present between the pile and ground water or...

40 CFR 264.251 - Design and operating requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... any migration of wastes out of the pile into the adjacent subsurface soil or ground water or surface... adjacent subsurface soil or ground water or surface water) during the active life of the facility. The... attenuative capacity and thickness of the liners and soils present between the pile and ground water or...

40 CFR 264.251 - Design and operating requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... any migration of wastes out of the pile into the adjacent subsurface soil or ground water or surface... adjacent subsurface soil or ground water or surface water) during the active life of the facility. The... attenuative capacity and thickness of the liners and soils present between the pile and ground water or...

Line-scan Raman imaging and spectroscopy platform for surface and subsurface evaluation of food safety and quality

USDA-ARS?s Scientific Manuscript database

Both surface and subsurface food inspection is important since interesting safety and quality attributes can be at different sample locations. This paper presents a multipurpose line-scan Raman platform for food safety and quality research, which can be configured for Raman chemical imaging (RCI) mo...

Nuclear subsurface explosion modeling and hydrodynamic fragmentation simulation of hazardous asteroids

NASA Astrophysics Data System (ADS)

Premaratne, Pavithra Dhanuka

Disruption and fragmentation of an asteroid using nuclear explosive devices (NEDs) is a highly complex yet a practical solution to mitigating the impact threat of asteroids with short warning time. A Hypervelocity Asteroid Intercept Vehicle (HAIV) concept, developed at the Asteroid Deflection Research Center (ADRC), consists of a primary vehicle that acts as kinetic impactor and a secondary vehicle that houses NEDs. The kinetic impactor (lead vehicle) strikes the asteroid creating a crater. The secondary vehicle will immediately enter the crater and detonate its nuclear payload creating a blast wave powerful enough to fragment the asteroid. The nuclear subsurface explosion modeling and hydrodynamic simulation has been a challenging research goal that paves the way an array of mission critical information. A mesh-free hydrodynamic simulation method, Smoothed Particle Hydrodynamics (SPH) was utilized to obtain both qualitative and quantitative solutions for explosion efficiency. Commercial fluid dynamics packages such as AUTODYN along with the in-house GPU accelerated SPH algorithms were used to validate and optimize high-energy explosion dynamics for a variety of test cases. Energy coupling from the NED to the target body was also examined to determine the effectiveness of nuclear subsurface explosions. Success of a disruption mission also depends on the survivability of the nuclear payload when the secondary vehicle approaches the newly formed crater at a velocity of 10 km/s or higher. The vehicle may come into contact with debris ejecting the crater which required the conceptual development of a Whipple shield. As the vehicle closes on the crater, its skin may also experience extreme temperatures due to heat radiated from the crater bottom. In order to address this thermal problem, a simple metallic thermal shield design was implemented utilizing a radiative heat transfer algorithm and nodal solutions obtained from hydrodynamic simulations.

Real rock-microfluidic flow cell: A test bed for real-time in situ analysis of flow, transport, and reaction in a subsurface reactive transport environment.

PubMed

Singh, Rajveer; Sivaguru, Mayandi; Fried, Glenn A; Fouke, Bruce W; Sanford, Robert A; Carrera, Martin; Werth, Charles J

2017-09-01

Physical, chemical, and biological interactions between groundwater and sedimentary rock directly control the fundamental subsurface properties such as porosity, permeability, and flow. This is true for a variety of subsurface scenarios, ranging from shallow groundwater aquifers to deeply buried hydrocarbon reservoirs. Microfluidic flow cells are now commonly being used to study these processes at the pore scale in simplified pore structures meant to mimic subsurface reservoirs. However, these micromodels are typically fabricated from glass, silicon, or polydimethylsiloxane (PDMS), and are therefore incapable of replicating the geochemical reactivity and complex three-dimensional pore networks present in subsurface lithologies. To address these limitations, we developed a new microfluidic experimental test bed, herein called the Real Rock-Microfluidic Flow Cell (RR-MFC). A porous 500μm-thick real rock sample of the Clair Group sandstone from a subsurface hydrocarbon reservoir of the North Sea was prepared and mounted inside a PDMS microfluidic channel, creating a dynamic flow-through experimental platform for real-time tracking of subsurface reactive transport. Transmitted and reflected microscopy, cathodoluminescence microscopy, Raman spectroscopy, and confocal laser microscopy techniques were used to (1) determine the mineralogy, geochemistry, and pore networks within the sandstone inserted in the RR-MFC, (2) analyze non-reactive tracer breakthrough in two- and (depth-limited) three-dimensions, and (3) characterize multiphase flow. The RR-MFC is the first microfluidic experimental platform that allows direct visualization of flow and transport in the pore space of a real subsurface reservoir rock sample, and holds potential to advance our understandings of reactive transport and other subsurface processes relevant to pollutant transport and cleanup in groundwater, as well as energy recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of Enabling Scientific Tools to Characterize the Geologic Subsurface at Hanford

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenna, Timothy C.; Herron, Michael M.

2014-07-08

This final report to the Department of Energy provides a summary of activities conducted under our exploratory grant, funded through U.S. DOE Subsurface Biogeochemical Research Program in the category of enabling scientific tools, which covers the period from July 15, 2010 to July 14, 2013. The main goal of this exploratory project is to determine the parameters necessary to translate existing borehole log data into reservoir properties following scientifically sound petrophysical relationships. For this study, we focused on samples and Ge-based spectral gamma logging system (SGLS) data collected from wells located in the Hanford 300 Area. The main activities consistedmore » of 1) the analysis of available core samples for a variety of mineralogical, chemical and physical; 2) evaluation of selected spectral gamma logs, environmental corrections, and calibration; 3) development of algorithms and a proposed workflow that permits translation of log responses into useful reservoir properties such as lithology, matrix density, porosity, and permeability. These techniques have been successfully employed in the petroleum industry; however, the approach is relatively new when applied to subsurface remediation. This exploratory project has been successful in meeting its stated objectives. We have demonstrated that our approach can lead to an improved interpretation of existing well log data. The algorithms we developed can utilize available log data, in particular gamma, and spectral gamma logs, and continued optimization will improve their application to ERSP goals of understanding subsurface properties.« less

Investigation of the influence of groundwater advection on energy extraction rates for sustainable borehole heat exchanger operation

NASA Astrophysics Data System (ADS)

Schelenz, Sophie; Dietrich, Peter; Vienken, Thomas

2016-04-01

A sustainable thermal exploitation of the shallow subsurface requires a precise understanding of all relevant heat transport processes. Currently, planning practice of shallow geothermal systems (especially for systems < 30 kW) focuses on conductive heat transport as the main energy source while the impact of groundwater flow as the driver for advective heat transport is neglected or strongly simplified. The presented study proves that those simplifications of complex geological and hydrogeological subsurface characteristics are insufficient for a precise evaluation of site-specific energy extraction rates. Based on synthetic model scenarios with varying subsurface conditions (groundwater flow velocity and aquifer thickness) the impact of advection on induced long term temperature changes in 5 and 10 m distance of the borehole heat exchanger is presented. Extending known investigations, this study enhances the evaluation of shallow geothermal energy extraction rates by considering conductive and advective heat transport under varying aquifer thicknesses. Further, it evaluates the impact of advection on installation lengths of the borehole heat exchanger to optimize the initial financial investment. Finally, an evaluation approach is presented that classifies relevant heat transport processes according to their Péclet number to enable a first quantitative assessment of the subsurface energy regime and recommend further investigation and planning procedures.

Radio Sounding Science at High Powers

NASA Technical Reports Server (NTRS)

Green, J. L.; Reinisch, B. W.; Song, P.; Fung, S. F.; Benson, R. F.; Taylor, W. W. L.; Cooper, J. F.; Garcia, L.; Markus, T.; Gallagher, D. L.

2004-01-01

Future space missions like the Jupiter Icy Moons Orbiter (JIMO) planned to orbit Callisto, Ganymede, and Europa can fully utilize a variable power radio sounder instrument. Radio sounding at 1 kHz to 10 MHz at medium power levels (10 W to kW) will provide long-range magnetospheric sounding (several Jovian radii) like those first pioneered by the radio plasma imager instrument on IMAGE at low power (less than l0 W) and much shorter distances (less than 5 R(sub E)). A radio sounder orbiting a Jovian icy moon would be able to globally measure time-variable electron densities in the moon ionosphere and the local magnetospheric environment. Near-spacecraft resonance and guided echoes respectively allow measurements of local field magnitude and local field line geometry, perturbed both by direct magnetospheric interactions and by induced components from subsurface oceans. JIMO would allow radio sounding transmissions at much higher powers (approx. 10 kW) making subsurface sounding of the Jovian icy moons possible at frequencies above the ionosphere peak plasma frequency. Subsurface variations in dielectric properties, can be probed for detection of dense and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts.

Methylmercury Mass Budgets and Distribution Characteristics in the Western Pacific Ocean.

PubMed

Kim, Hyunji; Soerensen, Anne L; Hur, Jin; Heimbürger, Lars-Eric; Hahm, Doshik; Rhee, Tae Siek; Noh, Seam; Han, Seunghee

2017-02-07

Methylmercury (MeHg) accumulation in marine organisms poses serious ecosystem and human health risk, yet the sources of MeHg in the surface and subsurface ocean remain uncertain. Here, we report the first MeHg mass budgets for the Western Pacific Ocean estimated based on cruise observations. We found the major net source of MeHg in surface water to be vertical diffusion from the subsurface layer (1.8-12 nmol m -2  yr -1 ). A higher upward diffusion in the North Pacific (12 nmol m -2  yr -1 ) than in the Equatorial Pacific (1.8-5.7 nmol m -2  yr -1 ) caused elevated surface MeHg concentrations observed in the North Pacific. We furthermore found that the slope of the linear regression line for MeHg versus apparent oxygen utilization in the Equatorial Pacific was about 2-fold higher than that in the North Pacific. We suggest this could be explained by redistribution of surface water in the tropical convergence-divergence zone, supporting active organic carbon decomposition in the Equatorial Pacific Ocean. On the basis of this study, we predict oceanic regions with high organic carbon remineralization to have enhanced MeHg concentrations in both surface and subsurface waters.

Monitoring subsurface coal fires in Jharia coalfield using observations of land subsidence from differential interferometric synthetic aperture radar (DInSAR)

NASA Astrophysics Data System (ADS)

Gupta, Nishant; Syed, Tajdarul H.; Athiphro, Ashiihrii

2013-10-01

Coal fires in the Jharia coalfield pose a serious threat to India's vital resource of primary coking coal and the regional environment. In order to undertake effective preventative measures, it is critical to detect the occurrence of subsurface coal fires and to monitor the extent of the existing ones. In this study, Differential Interferometric Synthetic Aperature Radar (DInSAR) technique has been utilized to monitor subsurface coal fires in the Jharia coalfield. Results showed that majority of the coal fire-related subsidence were concentrated on the eastern and western boundaries of the coalfield. The magnitude of subsidence observed was classified into high (10-27.8 mm), low (0-10 mm) and upliftment (-10-0 mm). The results were strongly supported by in situ observations and satellite-based thermal imagery analysis. Major subsidence was observed in the areas with repeated sightings of coal fire. Further, the study highlighted on the capability of the methodology for predicting potential coal fire zones on the basis of land surface subsidence only. The results from this study have major implications for demarcating the hazardous coal fire areas as well as effective implementation of public safety measures.

Utilization of the Deep Space Atomic Clock for Europa Gravitational Tide Recovery

NASA Technical Reports Server (NTRS)

Seubert, Jill; Ely, Todd

2015-01-01

Estimation of Europa's gravitational tide can provide strong evidence of the existence of a subsurface liquid ocean. Due to limited close approach tracking data, a Europa flyby mission suffers strong coupling between the gravity solution quality and tracking data quantity and quality. This work explores utilizing Low Gain Antennas with the Deep Space Atomic Clock (DSAC) to provide abundant high accuracy uplink-only radiometric tracking data. DSAC's performance, expected to exhibit an Allan Deviation of less than 3e-15 at one day, provides long-term stability and accuracy on par with the Deep Space Network ground clocks, enabling one-way radiometric tracking data with accuracy equivalent to that of its two-way counterpart. The feasibility of uplink-only Doppler tracking via the coupling of LGAs and DSAC and the expected Doppler data quality are presented. Violations of the Kalman filter's linearization assumptions when state perturbations are included in the flyby analysis results in poor determination of the Europa gravitational tide parameters. B-plane targeting constraints are statistically determined, and a solution to the linearization issues via pre-flyby approach orbit determination is proposed and demonstrated.

Integrated surface/subsurface permafrost thermal hydrology: Model formulation and proof-of-concept simulations

DOE PAGES

Painter, Scott L.; Coon, Ethan T.; Atchley, Adam L.; ...

2016-08-11

The need to understand potential climate impacts and feedbacks in Arctic regions has prompted recent interest in modeling of permafrost dynamics in a warming climate. A new fine-scale integrated surface/subsurface thermal hydrology modeling capability is described and demonstrated in proof-of-concept simulations. The new modeling capability combines a surface energy balance model with recently developed three-dimensional subsurface thermal hydrology models and new models for nonisothermal surface water flows and snow distribution in the microtopography. Surface water flows are modeled using the diffusion wave equation extended to include energy transport and phase change of ponded water. Variation of snow depth in themore » microtopography, physically the result of wind scour, is also modeled heuristically with a diffusion wave equation. The multiple surface and subsurface processes are implemented by leveraging highly parallel community software. Fully integrated thermal hydrology simulations on the tilted open book catchment, an important test case for integrated surface/subsurface flow modeling, are presented. Fine-scale 100-year projections of the integrated permafrost thermal hydrological system on an ice wedge polygon at Barrow Alaska in a warming climate are also presented. Finally, these simulations demonstrate the feasibility of microtopography-resolving, process-rich simulations as a tool to help understand possible future evolution of the carbon-rich Arctic tundra in a warming climate.« less

Growth of methanogens on a Mars soil simulant.

PubMed

Kral, Timothy A; Bekkum, Curtis R; McKay, Christopher P

2004-12-01

Currently, the surface of Mars is probably too cold, too dry, and too oxidizing for life, as we know it, to exist. But the subsurface is another matter. Life forms that might exist below the surface could not obtain their energy from photosynthesis, but rather they would have to utilize chemical energy. Methanogens are one type of microorganism that might be able to survive below the surface of Mars. A potential habitat for existence of methanogens on Mars might be a geothermal source of hydrogen, possibly due to volcanic or hydrothermal activity, or the reaction of basalt and anaerobic water, carbon dioxide, which is abundant in the martian atmosphere, and of course, subsurface liquid water. We report here that certain methanogens can grow on a Mars soil simulant when supplied with carbon dioxide, molecular hydrogen, and varying amounts of water.

Biogenic Carbon on Mars: A Subsurface Chauvinistic Viewpoint

NASA Astrophysics Data System (ADS)

Onstott, T. C.; Lau, C. Y. M.; Magnabosco, C.; Harris, R.; Chen, Y.; Slater, G.; Sherwood Lollar, B.; Kieft, T. L.; van Heerden, E.; Borgonie, G.; Dong, H.

2015-12-01

A review of 150 publications on the subsurface microbiology of the continental subsurface provides ~1,400 measurements of cellular abundances down to 4,800 meter depth. These data suggest that the continental subsurface biomass is comprised of ~1016-17 grams of carbon, which is higher than the most recent estimates of ~1015 grams of carbon (1 Gt) for the marine deep biosphere. If life developed early in Martian history and Mars sustained an active hydrological cycle during its first 500 million years, then is it possible that Mars could have developed a subsurface biomass of comparable size to that of Earth? Such a biomass would comprise a much larger fraction of the total known Martian carbon budget than does the subsurface biomass on Earth. More importantly could a remnant of this subsurface biosphere survive to the present day? To determine how sustainable subsurface life could be in isolation from the surface we have been studying subsurface fracture fluids from the Precambrian Shields in South Africa and Canada. In these environments the energetically efficient and deeply rooted acetyl-CoA pathway for carbon fixation plays a central role for chemolithoautotrophic primary producers that form the base of the biomass pyramid. These primary producers appear to be sustained indefinitely by H2 generated through serpentinization and radiolytic reactions. Carbon isotope data suggest that in some subsurface locations a much larger population of secondary consumers are sustained by the primary production of biogenic CH4 from a much smaller population of methanogens. These inverted biomass and energy pyramids sustained by the cycling of CH4 could have been and could still be active on Mars. The C and H isotopic signatures of Martian CH4 remain key tools in identifying potential signatures of an extant Martian biosphere. Based upon our results to date cavity ring-down spectroscopic technologies provide an option for making these measurements on future rover missions.

Neutron density profile in the lunar subsurface produced by galactic cosmic rays

NASA Astrophysics Data System (ADS)

Ota, Shuya; Sihver, Lembit; Kobayashi, Shingo; Hasebe, Nobuyuki

Neutron production by galactic cosmic rays (GCR) in the lunar subsurface is very important when performing lunar and planetary nuclear spectroscopy and space dosimetry. Further im-provements to estimate the production with increased accuracy is therefore required. GCR, which is a main contributor to the neutron production in the lunar subsurface, consists of not only protons but also of heavy components such as He, C, N, O, and Fe. Because of that, it is important to precisely estimate the neutron production from such components for the lunar spectroscopy and space dosimetry. Therefore, the neutron production from GCR particles in-cluding heavy components in the lunar subsurface was simulated with the Particle and Heavy ion Transport code System (PHITS), using several heavy ion interaction models. This work presents PHITS simulations of the neutron density as a function of depth (neutron density profile) in the lunar subsurface and the results are compared with experimental data obtained by Apollo 17 Lunar Neutron Probe Experiment (LNPE). From our previous study, it has been found that the accuracy of the proton-induced neutron production models is the most influen-tial factor when performing precise calculations of neutron production in the lunar subsurface. Therefore, a benchmarking of proton-induced neutron production models against experimental data was performed to estimate and improve the precision of the calculations. It was found that the calculated neutron production using the best model of Cugnon Old (E < 3 GeV) and JAM (E > 3 GeV) gave up to 30% higher values than experimental results. Therefore, a high energy nuclear data file (JENDL-HE) was used instead of the Cugnon Old model at the energies below 3 GeV. Then, the calculated neutron density profile successfully reproduced the experimental data from LNPE within experimental errors of 15% (measurement) + 30% (systematic). In this presentation, we summarize and discuss our calculated results of neutron production in the lunar subsurface.

Utilization of subsurface microbial electrochemical systems to elucidate the mechanisms of competition between methanogenesis and microbial iron(III)/humic acid reduction in Arctic peat soils

NASA Astrophysics Data System (ADS)

Friedman, E. S.; Miller, K.; Lipson, D.; Angenent, L. T.

2012-12-01

High-latitude peat soils are a major carbon reservoir, and there is growing concern that previously dormant carbon from this reservoir could be released to the atmosphere as a result of continued climate change. Microbial processes, such as methanogenesis and carbon dioxide production via iron(III) or humic acid reduction, are at the heart of the carbon cycle in Arctic peat soils [1]. A deeper understanding of the factors governing microbial dominance in these soils is crucial for predicting the effects of continued climate change. In previous years, we have demonstrated the viability of a potentiostatically-controlled subsurface microbial electrochemical system-based biosensor that measures microbial respiration via exocellular electron transfer [2]. This system utilizes a graphite working electrode poised at 0.1 V NHE to mimic ferric iron and humic acid compounds. Microbes that would normally utilize these compounds as electron acceptors donate electrons to the electrode instead. The resulting current is a measure of microbial respiration with the electrode and is recorded with respect to time. Here, we examine the mechanistic relationship between methanogenesis and iron(III)- or humic acid-reduction by using these same microbial-three electrode systems to provide an inexhaustible source of alternate electron acceptor to microbes in these soils. Chamber-based carbon dioxide and methane fluxes were measured from soil collars with and without microbial three-electrode systems over a period of four weeks. In addition, in some collars we simulated increased fermentation by applying acetate treatments to understand possible effects of continued climate change on microbial processes in these carbon-rich soils. The results from this work aim to increase our fundamental understanding of competition between electron acceptors, and will provide valuable data for climate modeling scenarios. 1. Lipson, D.A., et al., Reduction of iron (III) and humic substances plays a major role in anaerobic respiration in an Arctic peat soil. Journal of Geophysical Research-Biogeosciences, 2010. 115. 2. Friedman, E.S., et al., A cost-effective and field-ready potentiostat that poises subsurface electrodes to monitor bacterial respiration. Biosensors and Bioelectronics, 2012. 32(1): p. 309-313.

Line-scan spatially offset Raman spectroscopy for inspecting subsurface food safety and quality

USDA-ARS?s Scientific Manuscript database

This paper presented a method for subsurface food inspection using a newly developed line-scan spatially offset Raman spectroscopy (SORS) technique. A 785 nm laser was used as a Raman excitation source. The line-shape SORS data was collected in a wavenumber range of 0–2815 cm-1 using a detection mod...

3DHYDROGEOCHEM: A 3-DIMENSIONAL MODEL OF DENSITY-DEPENDENT SUBSURFACE FLOW AND THERMAL MULTISPECIES-MULTICOMPONENT HYDROGEOCHEMICAL TRANSPORT (EPA/600/SR-98/159)

EPA Science Inventory

This report presents a three-dimensional finite-element numerical model designed to simulate chemical transport in subsurface systems with temperature effect taken into account. The three-dimensional model is developed to provide (1) a tool of application, with which one is able ...

Presentations - Herriott, T.M. and others, 2015 | Alaska Division of

Science.gov Websites

fieldwork and subsurface data in a region of known oil and gas accumulations (poster): Geological Society of data in a region of known oil and gas accumulations (poster): Geological Society of America Slope, Alaska - Integration of fieldwork and subsurface data in a region of known oil and gas

Magnetic perturbation inspection of inner bearing races

NASA Technical Reports Server (NTRS)

Barton, J. R.; Lankford, J.

1972-01-01

Approximately 100 inner race bearings were inspected nondestructively prior to endurance testing. Two of the bearings which failed during testing spalled at the sites of subsurface inclusions previously detected by using magnetic field perturbation. At other sites initially judged to be suspect, subsurface inclusion-nucleated cracking was observed. Inspection records and metallurgical sectioning results are presented and discussed.

A passive low frequency instrument for radio wave sounding the subsurface oceans of the Jovian icy moons: An instrument concept

NASA Astrophysics Data System (ADS)

Hartogh, P.; Ilyushin, Ya. A.

2016-10-01

Exploration of subsurface oceans on Jovian icy moons is a key issue of the icy moons' geology. Electromagnetic wave propagation is the only way to probe their icy mantles from the orbit. In the present paper, a principal concept of a passive interferometric instrument for deep sounding of the icy moons' crust is proposed. Its working principle is measuring and correlating Jupiter's radio wave emissions with reflections from the deep sub-surface of the icy moons. A number of the functional aspects of the proposed experiment are studied, in particular, impact of the wave scattering on the surface terrain on the instrument performance and digital sampling of the noisy signal. Results of the test of the laboratory prototype of the instrument are also presented in the paper.

Subsurface Hydrology: Data Integration for Properties and Processes

NASA Astrophysics Data System (ADS)

Hyndman, David W.; Day-Lewis, Frederick D.; Singha, Kamini

Groundwater is a critical resource and the PrinciPal source of drinking water for over 1.5 billion people. In 2001, the National Research Council cited as a "grand challenge" our need to understand the processes that control water movement in the subsurface. This volume faces that challenge in terms of data integration between complex, multi-scale hydrologie processes, and their links to other physical, chemical, and biological processes at multiple scales. Subsurface Hydrology: Data Integration for Properties and Processes presents the current state of the science in four aspects: • Approaches to hydrologie data integration • Data integration for characterization of hydrologie properties • Data integration for understanding hydrologie processes • Meta-analysis of current interpretations Scientists and researchers in the field, the laboratory, and the classroom will find this work an important resource in advancing our understanding of subsurface water movement.

Impact of unseen assumptions on communication of atmospheric carbon mitigation options

NASA Astrophysics Data System (ADS)

Elliot, T. R.; Celia, M. A.; Court, B.

2010-12-01

With the rapid access and dissemination of information made available through online and digital pathways, there is need for a concurrent openness and transparency in communication of scientific investigation. Even with open communication it is essential that the scientific community continue to provide impartial result-driven information. An unknown factor in climate literacy is the influence of an impartial presentation of scientific investigation that has utilized biased base-assumptions. A formal publication appendix, and additional digital material, provides active investigators a suitable framework and ancillary material to make informed statements weighted by assumptions made in a study. However, informal media and rapid communiqués rarely make such investigatory attempts, often citing headline or key phrasing within a written work. This presentation is focused on Geologic Carbon Sequestration (GCS) as a proxy for the wider field of climate science communication, wherein we primarily investigate recent publications in GCS literature that produce scenario outcomes using apparently biased pro- or con- assumptions. A general review of scenario economics, capture process efficacy and specific examination of sequestration site assumptions and processes, reveals an apparent misrepresentation of what we consider to be a base-case GCS system. The authors demonstrate the influence of the apparent bias in primary assumptions on results from commonly referenced subsurface hydrology models. By use of moderate semi-analytical model simplification and Monte Carlo analysis of outcomes, we can establish the likely reality of any GCS scenario within a pragmatic middle ground. Secondarily, we review the development of publically available web-based computational tools and recent workshops where we presented interactive educational opportunities for public and institutional participants, with the goal of base-assumption awareness playing a central role. Through a series of interactive ‘what if’ scenarios, workshop participants were able to customize the models, which continue to be available from the Princeton University Subsurface Hydrology Research Group, and develop a better comprehension of subsurface factors contributing to GCS. Considering that the models are customizable, a simplified mock-up of regional GCS scenarios can be developed, which provides a possible pathway for informal, industrial, scientific or government communication of GCS concepts and likely scenarios. We believe continued availability, customizable scenarios, and simplifying assumptions are an exemplary means to communicate the possible outcome of CO2 sequestration projects; the associated risk; and, of no small importance, the consequences of base assumptions on predicted outcome.

Distribution-based fuzzy clustering of electrical resistivity tomography images for interface detection

NASA Astrophysics Data System (ADS)

Ward, W. O. C.; Wilkinson, P. B.; Chambers, J. E.; Oxby, L. S.; Bai, L.

2014-04-01

A novel method for the effective identification of bedrock subsurface elevation from electrical resistivity tomography images is described. Identifying subsurface boundaries in the topographic data can be difficult due to smoothness constraints used in inversion, so a statistical population-based approach is used that extends previous work in calculating isoresistivity surfaces. The analysis framework involves a procedure for guiding a clustering approach based on the fuzzy c-means algorithm. An approximation of resistivity distributions, found using kernel density estimation, was utilized as a means of guiding the cluster centroids used to classify data. A fuzzy method was chosen over hard clustering due to uncertainty in hard edges in the topography data, and a measure of clustering uncertainty was identified based on the reciprocal of cluster membership. The algorithm was validated using a direct comparison of known observed bedrock depths at two 3-D survey sites, using real-time GPS information of exposed bedrock by quarrying on one site, and borehole logs at the other. Results show similarly accurate detection as a leading isosurface estimation method, and the proposed algorithm requires significantly less user input and prior site knowledge. Furthermore, the method is effectively dimension-independent and will scale to data of increased spatial dimensions without a significant effect on the runtime. A discussion on the results by automated versus supervised analysis is also presented.

Arsenic Detoxification by Geobacter Species.

PubMed

Dang, Yan; Walker, David J F; Vautour, Kaitlin E; Dixon, Steven; Holmes, Dawn E

2017-02-15

Insight into the mechanisms for arsenic detoxification by Geobacter species is expected to improve the understanding of global cycling of arsenic in iron-rich subsurface sedimentary environments. Analysis of 14 different Geobacter genomes showed that all of these species have genes coding for an arsenic detoxification system (ars operon), and several have genes required for arsenic respiration (arr operon) and methylation (arsM). Genes encoding four arsenic repressor-like proteins were detected in the genome of G. sulfurreducens; however, only one (ArsR1) regulated transcription of the ars operon. Elimination of arsR1 from the G. sulfurreducens chromosome resulted in enhanced transcription of genes coding for the arsenic efflux pump (Acr3) and arsenate reductase (ArsC). When the gene coding for Acr3 was deleted, cells were not able to grow in the presence of either the oxidized or reduced form of arsenic, while arsC deletion mutants could grow in the presence of arsenite but not arsenate. These studies shed light on how Geobacter influences arsenic mobility in anoxic sediments and may help us develop methods to remediate arsenic contamination in the subsurface. This study examines arsenic transformation mechanisms utilized by Geobacter, a genus of iron-reducing bacteria that are predominant in many anoxic iron-rich subsurface environments. Geobacter species play a major role in microbially mediated arsenic release from metal hydroxides in the subsurface. This release raises arsenic concentrations in drinking water to levels that are high enough to cause major health problems. Therefore, information obtained from studies of Geobacter should shed light on arsenic cycling in iron-rich subsurface sedimentary environments, which may help reduce arsenic-associated illnesses. These studies should also help in the development of biosensors that can be used to detect arsenic contaminants in anoxic subsurface environments. We examined 14 different Geobacter genomes and found that all of these species possess genes coding for an arsenic detoxification system (ars operon), and some also have genes required for arsenic respiration (arr operon) and arsenic methylation (arsM). Copyright © 2017 American Society for Microbiology.

Arsenic Detoxification by Geobacter Species

PubMed Central

Walker, David J. F.; Vautour, Kaitlin E.; Dixon, Steven

2016-01-01

ABSTRACT Insight into the mechanisms for arsenic detoxification by Geobacter species is expected to improve the understanding of global cycling of arsenic in iron-rich subsurface sedimentary environments. Analysis of 14 different Geobacter genomes showed that all of these species have genes coding for an arsenic detoxification system (ars operon), and several have genes required for arsenic respiration (arr operon) and methylation (arsM). Genes encoding four arsenic repressor-like proteins were detected in the genome of G. sulfurreducens; however, only one (ArsR1) regulated transcription of the ars operon. Elimination of arsR1 from the G. sulfurreducens chromosome resulted in enhanced transcription of genes coding for the arsenic efflux pump (Acr3) and arsenate reductase (ArsC). When the gene coding for Acr3 was deleted, cells were not able to grow in the presence of either the oxidized or reduced form of arsenic, while arsC deletion mutants could grow in the presence of arsenite but not arsenate. These studies shed light on how Geobacter influences arsenic mobility in anoxic sediments and may help us develop methods to remediate arsenic contamination in the subsurface. IMPORTANCE This study examines arsenic transformation mechanisms utilized by Geobacter, a genus of iron-reducing bacteria that are predominant in many anoxic iron-rich subsurface environments. Geobacter species play a major role in microbially mediated arsenic release from metal hydroxides in the subsurface. This release raises arsenic concentrations in drinking water to levels that are high enough to cause major health problems. Therefore, information obtained from studies of Geobacter should shed light on arsenic cycling in iron-rich subsurface sedimentary environments, which may help reduce arsenic-associated illnesses. These studies should also help in the development of biosensors that can be used to detect arsenic contaminants in anoxic subsurface environments. We examined 14 different Geobacter genomes and found that all of these species possess genes coding for an arsenic detoxification system (ars operon), and some also have genes required for arsenic respiration (arr operon) and arsenic methylation (arsM). PMID:27940542

Efficacy of spray –Dried Pseudomonas fluorescens, strain CL145A (Zequanox®), for controlling Zebra Mussels (Dreissena polymorpha) within Lake Minnetonka, MN enclosures

USGS Publications Warehouse

Luoma, James A.; Severson, Todd J.

2016-01-01

The efficacy of whole water column and subsurface applications of the biopesticide Zequanox®, a commercially prepared spray-dried powder formulation of Pseudomonas fluorescens (strain CL145A), were evaluated for controlling zebra mussels (Dreissena polymorpha) within 27-m2 enclosures in Lake Minnetonka (Deephaven, Minnesota). Five treatments consisting of (1) two whole water column Zequanox applications, (2) two subsurface Zequanox applications, and (3) an untreated control were completed on each of three independent treatment days during September 2014. The two types of samplers used in the study were (1) type 1 samplers, which were custom built multi-plate samplers (wood, perforated aluminum, and tile substrates) that were placed into Robinson’s Bay in June of 2013 to allow for natural colonization by zebra mussels, and (2) type 2 samplers, which consisted of zebra mussels adhering to perforated aluminum trays that were placed into mesh containment bags. One day prior to treatment, three individual samplers of each type were distributed to test enclosures and exposed to a randomly assigned treatment. Sampling to determine the zebra mussel biomass adhering to type 1 samplers and the survival assessments for zebra mussels contained in type 2 samplers were completed ~40 days after exposure. The zebra mussel biomass adhering to type 1 samplers and the survival of zebra mussels contained in type 2 samplers were significantly less in groups treated with the highest Zequanox concentrations and in groups that received whole water column applications than comparable groups treated with lower Zequanox concentrations and subsurface applications. However, standardization of biomass and survival results to the amount of Zequanox applied showed that the lower concentrations and subsurface applications were more cost efficient, with respect to product used, at reducing zebra mussel biomass and for inducing zebra mussel mortality. Although the subsurface application methods and lower treatment concentrations were more cost efficient, biological significance and management goals should be evaluated prior to selecting the application method. Development and refinement of additional application techniques may improve the utility of the subsurface Zequanox applications.

Mini-RF and LROC observations of mare crater layering relationships

NASA Astrophysics Data System (ADS)

Stickle, A. M.; Patterson, G. W.; Cahill, J. T. S.; Bussey, D. B. J.

2016-07-01

The lunar maria cover approximately 17% of the Moon's surface. Discerning discrete subsurface layers in the mare provides some constraints on thickness and volume estimates of mare volcanism. Multiple types of data and measurement techniques allow probing the subsurface and provide insights into these layers, including detailed examination of impact craters, mare pits and sinuous rilles, and radar sounders. Unfortunately, radar sounding includes many uncertainties about the material properties of the lunar surface that may influence estimates of layer depth and thickness. Because they distribute material from depth onto the surface, detailed examination of impact ejecta blankets provides a reliable way to examine deeper material using orbital instruments such as cameras, spectrometers, or imaging radars. Here, we utilize Miniature Radio Frequency (Mini-RF) data to investigate the scattering characteristics of ejecta blankets of young lunar craters. We use Circular Polarization Ratio (CPR) information from twenty-two young, fresh lunar craters to examine how the scattering behavior changes as a function of radius from the crater rim. Observations across a range of crater size and relative ages exhibit significant diversity within mare regions. Five of the examined craters exhibit profiles with no shelf of constant CPR near the crater rim. Comparing these CPR profiles with LROC imagery shows that the magnitude of the CPR may be an indication of crater degradation state; this may manifest differently at radar compared to optical wavelengths. Comparisons of radar and optical data also suggest relationships between subsurface stratigraphy and structure in the mare and the block size of the material found within the ejecta blanket. Of the examined craters, twelve have shelves of approximately constant CPR as well as discrete layers outcropping in the subsurface, and nine fall along a trend line when comparing shelf-width with thickness of subsurface layers. These observations suggest that surface CPR measurements may be used to identify near-surface layering. Here, we use ejected material to probe the subsurface, allowing observations of near-surface stratigraphy that may be otherwise hidden by layers higher from remote observations.

Design Evolution Study - Aging Options

DOE Office of Scientific and Technical Information (OSTI.GOV)

P. McDaniel

The purpose of this study is to identify options and issues for aging commercial spent nuclear fuel received for disposal at the Yucca Mountain Mined Geologic Repository. Some early shipments of commercial spent nuclear fuel to the repository may be received with high-heat-output (younger) fuel assemblies that will need to be managed to meet thermal goals for emplacement. The capability to age as much as 40,000 metric tons of heavy metal of commercial spent nuclear he1 would provide more flexibility in the design to manage this younger fuel and to decouple waste receipt and waste emplacement. The following potential agingmore » location options are evaluated: (1) Surface aging at four locations near the North Portal; (2) Subsurface aging in the permanent emplacement drifts; and (3) Subsurface aging in a new subsurface area. The following aging container options are evaluated: (1) Complete Waste Package; (2) Stainless Steel inner liner of the waste package; (3) Dual Purpose Canisters; (4) Multi-Purpose Canisters; and (5) New disposable canister for uncanistered commercial spent nuclear fuel. Each option is compared to a ''Base Case,'' which is the expected normal waste packaging process without aging. A Value Engineering approach is used to score each option against nine technical criteria and rank the options. Open issues with each of the options and suggested future actions are also presented. Costs for aging containers and aging locations are evaluated separately. Capital costs are developed for direct costs and distributable field costs. To the extent practical, unit costs are presented. Indirect costs, operating costs, and total system life cycle costs will be evaluated outside of this study. Three recommendations for aging commercial spent nuclear fuel--subsurface, surface, and combined surface and subsurface are presented for further review in the overall design re-evaluation effort. Options that were evaluated but not recommended are: subsurface aging in a new subsurface area (high cost); surface aging in the complete waste package (risk to the waste package and impact on the Waste Handling Facility); and aging in the stainless steel liner (impact on the waste package design and new high risk operations added to the waste packaging process). The selection of a design basis for aging will be made in conjunction with the other design re-evaluation studies.« less

Forensic Assessment on Ground Instability Using Electrical Resistivity Imaging (ERI)

NASA Astrophysics Data System (ADS)

Hazreek, Z. A. M.; Azhar, A. T. S.; Aziman, M.; Fauzan, S. M. S. A.; Ikhwan, J. M.; Aishah, M. A. N.

2017-02-01

Electrical resistivity imaging (ERI) was used to evaluate the ground settlement in local scale at housing areas. ERI and Borehole results were used to interpret the condition of the problematic subsurface profile due to its differential stiffness. Electrical resistivity of the subsurface profile was measured using ABEM SAS4000 equipment set. ERI results using electrical resistivity anomaly on subsurface materials resistivity shows the subsurface profile exhibited low (1 - 100 Ωm) and medium (> 100 Ωm) value (ERV) representing weak to firm materials. The occurrences of soft to medium cohesive material (SPT N value = 2 - 7) and stiff cohesive material (SPT N ≥ 8) in local scale has created inconsistency of the ground stability condition. Moreover, it was found that a layer of organic decayed wood (ERV = 43 ˜ 29 Ωm & SPT N = 15 ˜ 9) has been buried within the subsurface profile thus weaken the ground structure and finally promoting to the ground settlement. The heterogeneous of the subsurface material presented using integrated analysis of ERI and borehole data enabled ground settlement in this area to be evaluated. This is the major factor evaluating ground instability in the local scale. The result was applicable to assist in planning a strategy for sustainable ground improvement of local scale in fast, low cost, and large data coverage.

Site Classification using Multichannel Channel Analysis of Surface Wave (MASW) method on Soft and Hard Ground

NASA Astrophysics Data System (ADS)

Ashraf, M. A. M.; Kumar, N. S.; Yusoh, R.; Hazreek, Z. A. M.; Aziman, M.

2018-04-01

Site classification utilizing average shear wave velocity (Vs(30) up to 30 meters depth is a typical parameter. Numerous geophysical methods have been proposed for estimation of shear wave velocity by utilizing assortment of testing configuration, processing method, and inversion algorithm. Multichannel Analysis of Surface Wave (MASW) method is been rehearsed by numerous specialist and professional to geotechnical engineering for local site characterization and classification. This study aims to determine the site classification on soft and hard ground using MASW method. The subsurface classification was made utilizing National Earthquake Hazards Reduction Program (NERHP) and international Building Code (IBC) classification. Two sites are chosen to acquire the shear wave velocity which is in the state of Pulau Pinang for soft soil and Perlis for hard rock. Results recommend that MASW technique can be utilized to spatially calculate the distribution of shear wave velocity (Vs(30)) in soil and rock to characterize areas.

SUBSURFACE RESIDENCE TIMES AS AN ALGORITHM FOR AQUIFER SENSITIVITY MAPPING: TESTING THE CONCEPT WITH GROUND WATER MODELS IN THE CONTENTNEA CREEK BASIN, NORTH CAROLINA, USA

EPA Science Inventory

This poster will present a modeling and mapping assessment of landscape sensitivity to non-point source pollution as applied to a hierarchy of catchment drainages in the Coastal Plain of the state of North Carolina. Analysis of the subsurface residence time of water in shallow a...

The WISDOM Radar: Unveiling the Subsurface Beneath the ExoMars Rover and Identifying the Best Locations for Drilling

PubMed Central

Clifford, Stephen; Plettemeier, Dirk; Le Gall, Alice; Hervé, Yann; Dorizon, Sophie; Quantin-Nataf, Cathy; Benedix, Wolf-Stefan; Schwenzer, Susanne; Pettinelli, Elena; Heggy, Essam; Herique, Alain; Berthelier, Jean-Jacques; Kofman, Wlodek; Vago, Jorge L.; Hamran, Svein-Erik

2017-01-01

Abstract The search for evidence of past or present life on Mars is the principal objective of the 2020 ESA-Roscosmos ExoMars Rover mission. If such evidence is to be found anywhere, it will most likely be in the subsurface, where organic molecules are shielded from the destructive effects of ionizing radiation and atmospheric oxidants. For this reason, the ExoMars Rover mission has been optimized to investigate the subsurface to identify, understand, and sample those locations where conditions for the preservation of evidence of past life are most likely to be found. The Water Ice Subsurface Deposit Observation on Mars (WISDOM) ground-penetrating radar has been designed to provide information about the nature of the shallow subsurface over depth ranging from 3 to 10 m (with a vertical resolution of up to 3 cm), depending on the dielectric properties of the regolith. This depth range is critical to understanding the geologic evolution stratigraphy and distribution and state of subsurface H2O, which provide important clues in the search for life and the identification of optimal drilling sites for investigation and sampling by the Rover's 2-m drill. WISDOM will help ensure the safety and success of drilling operations by identification of potential hazards that might interfere with retrieval of subsurface samples. Key Words: Ground penetrating radar—Martian shallow subsurface—ExoMars. Astrobiology 17, 565–584.

Manipulation of subsurface carbon nanoparticles in Bi 2 Sr 2 CaCu 2 O 8 + δ using a scanning tunneling microscope

DOE PAGES

Stollenwerk, A. J.; Hurley, N.; Beck, B.; ...

2015-03-19

In this study, we present evidence that subsurface carbon nanoparticles in Bi₂Sr₂CaCu₂O 8+δ can be manipulated with nanometer precision using a scanning tunneling microscope. High resolution images indicate that most of the carbon particles remain subsurface after transport observable as a local increase in height as the particle pushes up on the surface. Tunneling spectra in the vicinity of these protrusions exhibit semiconducting characteristics with a band gap of approximately 1.8 eV, indicating that the incorporation of carbon locally alters the electronic properties near the surface.

3D subsurface geological modeling using GIS, remote sensing, and boreholes data

NASA Astrophysics Data System (ADS)

Kavoura, Katerina; Konstantopoulou, Maria; Kyriou, Aggeliki; Nikolakopoulos, Konstantinos G.; Sabatakakis, Nikolaos; Depountis, Nikolaos

2016-08-01

The current paper presents the combined use of geological-geotechnical insitu data, remote sensing data and GIS techniques for the evaluation of a subsurface geological model. High accuracy Digital Surface Model (DSM), airphotos mosaic and satellite data, with a spatial resolution of 0.5m were used for an othophoto base map compilation of the study area. Geological - geotechnical data obtained from exploratory boreholes and the 1:5000 engineering geological maps were digitized and implemented in a GIS platform for a three - dimensional subsurface model evaluation. The study is located at the North part of Peloponnese along the new national road.

Modelling of EISS GPR's electrical and magnetic antennas for ExoMars mission

NASA Astrophysics Data System (ADS)

Biancheri-Astier, M.; Ciarletti, V.; Reineix, A.; Corbel, C.; Dolon, F.; Simon, Y.; Caudoux, C.; Lapauw, L.; Berthelier, Jj.; Ney, R.

2009-04-01

Despite several past and present missions to Mars, very little information is available on its subsurface. One of the scientific objectives of the European ExoMars mission (ESA) is to characterize the water / geochemical environment as a function of depth and investigate the planet subsurface to better understand the evolution and habitability of the planet. The electromagnetic survey of subsurface will provide a nondestructive way to probe the subsurface and look for potential deep liquid water reservoirs. The LATMOS (ex CETP) is currently developing a ground penetrating radar (GPR) called EISS "Electromagnetic Investigation of the Sub Surface", which is a enhanced version of the TAPIR "Terrestrial and Planetary Imaging Radar", developed in the frame of the Netlander mission cancelled in 2004. The GPR main objective is to perform sounding of the sub-surface down to kilometric depth. EISS is an impulse GPR operating, from the Martian surface, at HF frequencies (~ 2-4MHz) with a wide bandwidth (100kHz-5MHz). EISS can operate in four modes: impedance measurement, mono and bi-static survey, passive mode. The EISS innovative concept is based on the use of the fixed station (Lander) and mobile rover to conduct subsurface surveys of the area visited by the Rover. The work at HF frequencies, EISS uses a half-wave resistively loaded dipole electrical antenna i.e. two monopoles 35 meters long each to transmit (and also receive in mono-static mode) the signal. The resistive profile of the antenna follows a Wu-King profile which is optimized to transmit the pulse without noticeable distortion and avoid ringing. The two monopoles will be deployed in roughly opposite directions on the surface of Mars. The exact value of the direction of deployment for each monopole will be chosen in order to minimize the contact with the Lander structure, avoid obstacles and the solar panels still ensuring a good coverage of the whole area. In bi-static mode, the signal is received with a small magnetic sensor accommodated on the Rover. As a consequence, since the direction that the rover will follow after its egress will not be know until the Lander is on Mars, it is essential to chose a configuration that will result in a radiation pattern compatible with bi-static measurements whatever the direction of the rover is (within a distance of 1 kilometer). Studies based on electromagnetic simulations have been performed to check the impact of the angle between the two monopoles on the radiation pattern. Study of EISS performances is ongoing using numerical modeling and experimental verifications. We use numerical simulation (FDTD code), analytical models and data processing algorithms to determine the performances of each operating mode and to prepare data interpretation. The subsurface survey requires knowledge of the permittivity of the studied sub-surface layers to convert the measured propagation delay into distance. Access to electrical characteristics of ground without return samples and in situ analysis is unusual in space missions and aroused great interest. Results will be presented about different ways EISS can provide estimation of the electrical properties of the shallow subsurface. Simulations that highlight the impact of the chosen resistive profile and of the angle between the two deployed monopoles will be shown. The presentation will mainly be focused on the bi-static mode that greatly improves the 3D representation of subsurface structure and on the associated instrumental requirements such as the perfect synchronization of the two part of the instrument. A method to retrieve the direction of arrival for each detected echo will be presented that allows a more accurate sub-surface mapping. Only the three magnetic field components are required to implement it, which makes the EISS configuration particularly interesting. This method is based on the orthogonality between the propagation vector and the polarization plane.

Organic and Inorganic Carbon in the Rio Tinto (Spain) Deep Subsurface System: a Possible Model for Subsurface Carbon and Lithoautotrophs on Mars.

NASA Astrophysics Data System (ADS)

Bonaccorsi, R.; Stoker, C. R.; MARTE Science Team

2007-12-01

The subsurface is the key environment for searching for life on planets lacking surface life. Subsurface ecosystems are of great relevance to astrobiology including the search for past/present life on Mars. Conditions on the Martian surface do not support biological activity but the subsurface might preserve organics and host subsurface life [1]. A key requirement for the analysis of subsurface samples on Mars is the ability to characterize organic vs. inorganic carbon pools. This information is needed to determine if the sample contains organic material of biological origin and/ or to establish if pools of inorganic carbon can support subsurface biospheres. The Mars Analog Rio Tinto Experiment (MARTE) performed deep drilling of cores i.e., down to 165-m depth, in a volcanically-hosted-massive-sulfide deposit at Rio Tinto, Spain, which is considered an important analog of the Sinus Meridiani site on Mars. Results from MARTE suggest the existence of a relatively complex subsurface life including aerobic and anaerobic chemoautotrophs, and strict anaerobic methanogens sustained by Fe and S minerals in anoxic conditions, which is an ideal model analog for a deep subsurface Martian environment. We report here on the distribution of organic (C-org: 0.01-0.3Wt% and inorganic carbon (IC = 0.01-7.0 Wt%) in a subsurface rock system including weathered/oxidized i.e., gossan, and unaltered pyrite stockwork. Cores were analyzed from 3 boreholes (BH-4, BH-7, and BH-8) that penetrated down to a depth of ~165 m into massive sulfide. Nearsurface phyllosilicate rich-pockets contain the highest amounts of organics (0.3Wt%) [2], while the deeper rocks contain the highest amount of carbonates. Assessing the amount of C pools available throughout the RT subsurface brings key insight on the type of trophic system sustaining its microbial ecosystem (i.e., heterotrophs vs. autotrophs) and the biogeochemical relationships that characterize a new type of subsurface biosphere at RT. This potentially novel biosphere on Earth could be used as a model to test for extant and extinct life on Mars. Furthermore, having found carbonates in an hyperacidic system (pH ~2.3) brings new insights on the possible occurrence of deep carbonates deposits under low-pH condition on Mars. [1] Boston, P.J., et al., 1992. Icarus 95,300-308; Bonaccorsi, Stoker and Sutter, 2007 Accepted with review in Astrobiology.

4-D Model of CO2 Deposition at North and South of Mars from HEND/Odyssey and MOLA/MGS

NASA Technical Reports Server (NTRS)

Litvak, M. L.; Mitrofanov, I. G.; Kozyrev, A. S.; Sanin, A. B.; Tretyakov, V.; Smith, D. E.; Zuber, M. T.; Boynton, W. V.; Hamara, D. K.; Shinohara, C.

2003-01-01

The first 1.5 year of neutron mapping measurements onboard Mars Odyssey spacecraft are presented based on High Energy Neutron Detector (HEND) observations. HEND instrument is a part of GRS suite responsible for registration of epithermal and fast neutrons originating in Mars subsurface layer. The scattering of fast neutrons in Mars surface caused by primary cosmic rays is strongly sensitive to presence of hydrogen atoms. Even several percents of subsurface water significantly depress epithermal and fast neutron flux. It turns orbit neutron spectroscopy into one of most efficient methods for finding distribution of subsurface water. The Mars Odyssey observations revealed huge water- ice regions above 60N and 60S latitudes. It was founded that distribution of subsurface water has layered structure at these regions. It is thought that more than 50% wt water ice covered by relatively dry layer with different thickness.

Kinematics of reflections in subsurface offset and angle-domain image gathers

NASA Astrophysics Data System (ADS)

Dafni, Raanan; Symes, William W.

2018-05-01

Seismic migration in the angle-domain generates multiple images of the earth's interior in which reflection takes place at different scattering-angles. Mechanically, the angle-dependent reflection is restricted to happen instantaneously and at a fixed point in space: Incident wave hits a discontinuity in the subsurface media and instantly generates a scattered wave at the same common point of interaction. Alternatively, the angle-domain image may be associated with space-shift (regarded as subsurface offset) extended migration that artificially splits the reflection geometry. Meaning that, incident and scattered waves interact at some offset distance. The geometric differences between the two approaches amount to a contradictory angle-domain behaviour, and unlike kinematic description. We present a phase space depiction of migration methods extended by the peculiar subsurface offset split and stress its profound dissimilarity. In spite of being in radical contradiction with the general physics, the subsurface offset reveals a link to some valuable angle-domain quantities, via post-migration transformations. The angle quantities are indicated by the direction normal to the subsurface offset extended image. They specifically define the local dip and scattering angles if the velocity at the split reflection coordinates is the same for incident and scattered wave pairs. Otherwise, the reflector normal is not a bisector of the opening angle, but of the corresponding slowness vectors. This evidence, together with the distinguished geometry configuration, fundamentally differentiates the angle-domain decomposition based on the subsurface offset split from the conventional decomposition at a common reflection point. An asymptotic simulation of angle-domain moveout curves in layered media exposes the notion of split versus common reflection point geometry. Traveltime inversion methods that involve the subsurface offset extended migration must accommodate the split geometry in the inversion scheme for a robust and successful convergence at the optimal velocity model.

In-Situ Contained And Of Volatile Soil Contaminants

DOEpatents

Varvel, Mark Darrell

2005-12-27

The invention relates to a novel approach to containing and removing toxic waste from a subsurface environment. More specifically the present invention relates to a system for containing and removing volatile toxic chemicals from a subsurface environment using differences in surface and subsurface pressures. The present embodiment generally comprises a deep well, a horizontal tube, at least one injection well, at least one extraction well and a means for containing the waste within the waste zone (in-situ barrier). During operation the deep well air at the bottom of well (which is at a high pressure relative to the land surface as well as relative to the air in the contaminated soil) flows upward through the deep well (or deep well tube). This stream of deep well air is directed into the horizontal tube, down through the injection tube(s) (injection well(s)) and into the contaminate plume where it enhances volatization and/or removal of the contaminants.

In-Situ Containment and Extraction of Volatile Soil Contaminants

DOEpatents

Varvel, Mark Darrell

2005-12-27

The invention relates to a novel approach to containing and removing toxic waste from a subsurface environment. More specifically the present invention relates to a system for containing and removing volatile toxic chemicals from a subsurface environment using differences in surface and subsurface pressures. The present embodiment generally comprises a deep well, a horizontal tube, at least one injection well, at least one extraction well and a means for containing the waste within the waste zone (in-situ barrier). During operation the deep well air at the bottom of well (which is at a high pressure relative to the land surface as well as relative to the air in the contaminated soil) flows upward through the deep well (or deep well tube). This stream of deep well air is directed into the horizontal tube, down through the injection tube(s) (injection well(s)) and into the contaminate plume where it enhances volatization and/or removal of the contaminants.

Utilizing Gravity Methods for Regional Studies in Basin Delineation: Case Study at Jornada del Muerto basin, New Mexico

NASA Astrophysics Data System (ADS)

Villalobos, J. I.

2005-12-01

The modeling of basin structures is an important step in the development of plans and policies for ground water management. To facilitate in the analysis of large scale regional structures, gravity data is implemented to examine the overall structural trend of the region. The gravitational attraction of structures in the upper mantle and crust provide vital information about the possible structure and composition of a region. Improved availability of gravity data via internet has promoted extensive construction and interpretation of gravity maps in the analysis of sub-surface structural anomalies. The utilization of gravity data appears to be particularly worthwhile because it is a non-invasive and inexpensive means of addressing the subsurface tectonic framework of large scale regions. In this paper, the author intends to illustrate 1) acquisition of gravity data and its processing; 2) interpretation of gravity data; and 3) sources of uncertainty and errors by using a case study of the Jornada del Muerto basin in South-Central New Mexico where integrated gravity data inferred several faults, sub-basins and thickness variations within the basins structure. The author also explores the integration of gravity method with other geophysical methods to further refine the delineation of basins.

Pilot-Scale Demonstration of In-Situ Chemical Oxidation ...

EPA Pesticide Factsheets

A pilot-scale in situ chemical oxidation (ISCO) demonstration, involving subsurface injections of sodium permanganate (NaMnO4), was performed at the US Marine Corp Recruit Depot (MCRD), site 45 (Parris Island (PI), SC). The ground water was originally contaminated with perchloroethylene (PCE) (also known as tetrachloroethylene), a chlorinated solvent used in dry cleaner operations. High resolution site characterization involved multiple iterations of soil core sampling and analysis. Nested micro-wells and conventional wells were also used to sample and analyze ground water for PCE and decomposition products (i.e., trichloroethyelene (TCE), dichloroethylene (c-DCE, t-DCE), and vinyl chloride (VC)), collectively referred to as chlorinated volatile organic compounds (CVOC). This characterization methodology was used to develop and refine the conceptual site model and the ISCO design, not only by identifying CVOC contamination but also by eliminating uncontaminated portions of the aquifer from further ISCO consideration. Direct-push injection was selected as the main method of NaMnO4 delivery due to its flexibility and low initial capital cost. Site impediments to ISCO activities in the source area involved subsurface utilities, including a high pressure water main, a high voltage power line, a communication line, and sanitary and stormwater sewer lines. Utility markings were used in conjunction with careful planning and judicious selection of injection locations. A

Active CO2 Reservoir Management for Carbon Capture, Utilization, and Sequestration: Impact on Permitting, Monitoring, and Public Acceptance

NASA Astrophysics Data System (ADS)

Buscheck, T. A.; Chen, M.; Sun, Y.; Hao, Y.; Court, B.; Celia, M. A.; Wolery, T.; Aines, R. D.

2011-12-01

CO2 capture and sequestration (CCS) integrated with geothermal energy production in deep geological formations can play an important role in reducing CO2 emissions to the atmosphere and thereby mitigate global climate change. For industrial-scale CO2 injection in saline formations, pressure buildup can limit storage capacity and security. Active CO2 Reservoir Management (ACRM) combines brine production with CO2 injection to relieve pressure buildup, increase injectivity, manipulate CO2 migration, constrain brine leakage, and enable beneficial utilization of produced brine. Therefore, ACRM can be an enabler of carbon capture, utilization, and sequestration (CCUS). Useful products may include freshwater, cooling water, make-up water for pressure support in oil, gas, and geothermal reservoir operations, and geothermal energy production. Implementation barriers to industrial-scale CCS include concerns about (1) CO2 sequestration security and assurance, (2) pore-space competition with neighboring subsurface activities, (3) CO2 capture costs, and (4) water-use demands imposed by CCS operations, which is particularly important where water resources are already scarce. CCUS, enabled by ACRM, has the potential of addressing these barriers. Pressure relief from brine production can substantially reduce the driving force for potential CO2 and brine migration, as well as minimize interference with neighboring subsurface activities. Electricity generated from geothermal energy can offset a portion of the parasitic energy and financial costs of CCS. Produced brine can be used to generate freshwater by desalination technologies, such as RO, provide a source for saltwater cooling systems or be used as make-up water for oil, gas, or geothermal reservoir operations, reducing the consumption of valuable freshwater resources. We examine the impact of brine production on reducing CO2 and brine leakage. A volumetric balance between injected and produced fluids minimizes the spatial extent of the pressure perturbation, substantially reducing both the Area of Review (AoR) and interactions with neighboring subsurface activities. This will reduce pore-space competition between neighboring subsurface activities, allowing for independent planning, assessment, and permitting. Because post-injection pressure buildup is virtually eliminated, this could have a major impact on post-injection monitoring requirements. Reducing the volume of rock over which brine can migrate may significantly affect site characterization requirements, as well as the impact of parametric and conceptual model uncertainties, such as those related to abandoned wells. ACRM-CCUS has the potential of playing a beneficial role in site-characterization, permitting, and monitoring activities, and in gaining public acceptance. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Characterizing near-surface elemental layering on Mars using gamma-ray spectroscopy: A proof-of-principle experiment

NASA Astrophysics Data System (ADS)

Peplowski, Patrick N.; Wilson, Jack T.; Beck, Andrew W.; Burks, Morgan; Goldsten, John O.; Lawrence, David J.

2018-01-01

Gamma-ray spectroscopy investigations characterize the chemical composition of planetary surfaces by measuring element-characteristic gamma rays with energies of ∼100 keV to ∼9 MeV. Over this energy range, the mean free path of a gamma ray varies from about 1 to 25 cm, therefore gamma-ray measurements sample subsurface composition. Many elements emit gamma rays at multiple, often widely spaced energies, so gamma-ray measurements can in principle also be used to identify depth-dependent variations in subsurface composition. We report results from laboratory measurements and radiation transport modeling designed to demonstrate this capability. The laboratory measurements verified the presence of depth-dependent gamma-ray signatures, and were then used to benchmark radiation transport simulations that were used to model realistic Mars-like scenarios. The models indicate that compositionally distinct subsurface deposits, buried to depths of ∼80 cm (125 g/cm2), can be identified using gamma-ray measurements. Going beyond identification to characterization (burial depth, relative composition of the layers) of the deposits requires knowledge of the vertical and horizontal variability in the water content of the near-surface surface materials, the local Galactic Cosmic Ray environment (magnitude and energy distribution), the depth-dependent neutron flux, gamma-ray production cross sections, and knowledge of the composition and column density of the atmosphere. The results of our experiments and models provided a basis for examining the utility of using orbiter- and lander-based gamma-ray measurements to identify subsurface deposits on Mars.

High Resolution ground penetrating radar (GPR) measurements at the laboratory scale to model porosity and permeability in the Miami Limestone in South Florida.

NASA Astrophysics Data System (ADS)

Mount, G. J.; Comas, X.

2015-12-01

Subsurface water flow within the Biscayne aquifer is controlled by the heterogeneous distribution of porosity and permeability in the karst Miami Limestone and the presence of numerous dissolution and mega-porous features. The dissolution features and other high porosity areas can create preferential flow paths and direct recharge to the aquifer, which may not be accurately conceptualized in groundwater flow models. As hydrologic conditions are undergoing restoration in the Everglades, understanding the distribution of these high porosity areas within the subsurface would create a better understanding of subsurface flow. This research utilizes ground penetrating radar to estimate the spatial variability of porosity and dielectric permittivity of the Miami Limestone at centimeter scale resolution at the laboratory scale. High frequency GPR antennas were used to measure changes in electromagnetic wave velocity through limestone samples under varying volumetric water contents. The Complex Refractive Index Model (CRIM) was then applied in order to estimate porosity and dielectric permittivity of the solid phase of the limestone. Porosity estimates ranged from 45.2-66.0% from the CRIM model and correspond well with estimates of porosity from analytical and digital image techniques. Dielectric permittivity values of the limestone solid phase ranged from 7.0 and 13.0, which are similar to values in the literature. This research demonstrates the ability of GPR to identify the cm scale spatial variability of aquifer properties that influence subsurface water flow which could have implications for groundwater flow models in the Biscayne and potentially other shallow karst aquifers.

Assessing conceptual models for subsurface reactive transport of inorganic contaminants

USGS Publications Warehouse

Davis, James A.; Yabusaki, Steven B.; Steefel, Carl; Zachara, John M.; Curtis, Gary P.; Redden, George D.; Criscenti, Louise J.; Honeyman, Bruce D.

2004-01-01

In many subsurface situations where human health and environmental quality are at risk (e.g., contaminant hydrogeology petroleum extraction, carbon sequestration, etc.),scientists and engineers are being asked by federal agency decision-makers to predict the fate of chemical species under conditions where both reactions and transport are processes of first-order importance.In 2002, a working group (WG) was formed by representatives of the U.S. Geological Survey, Environmental Protection Agency, Department of Energy Nuclear Regulatory Commission, Department of Agriculture, and Army Engineer Research and Development Center to assess the role of reactive transport modeling (RTM) in addressing these situations. Specifically the goals of the WG are to (1) evaluate the state of the art in conceptual model development and parameterization for RTM, as applied to soil,vadose zone, and groundwater systems, and (2) prioritize research directions that would enhance the practical utility of RTM.

Prediction of halite, gypsum, and anhydrite solubility in natural brines under subsurface conditions

NASA Astrophysics Data System (ADS)

He, Shiliang; Morse, John W.

1993-01-01

Prediction of the solubility of the evaporite minerals halite, gypsum, and anhydrite in brines has numerous scientific and practical applications. This paper presents a Pitzer equation-based model for predicting the solubility of these minerals in Na +-K +-H +-Ca 2+-Mg 2+-Cl --OH --SO 42--H 2O solutions of varying composition as a function of temperature and pressure. Model predictions compare well with experimental observations. As an example of the utility of this program, the volume of CaSO 4 precipitated as a brine flows up a pipe from 6000 m depth is predicted. This is done as a function of flow distance for different cooling rates of the brine. Results indicate that if the brine can be cooled to near the geothermal gradient no precipitation will take place.

Integrating experimental and numerical methods for a scenario-based quantitative assessment of subsurface energy storage options

NASA Astrophysics Data System (ADS)

Kabuth, Alina; Dahmke, Andreas; Hagrey, Said Attia al; Berta, Márton; Dörr, Cordula; Koproch, Nicolas; Köber, Ralf; Köhn, Daniel; Nolde, Michael; Tilmann Pfeiffer, Wolf; Popp, Steffi; Schwanebeck, Malte; Bauer, Sebastian

2016-04-01

Within the framework of the transition to renewable energy sources ("Energiewende"), the German government defined the target of producing 60 % of the final energy consumption from renewable energy sources by the year 2050. However, renewable energies are subject to natural fluctuations. Energy storage can help to buffer the resulting time shifts between production and demand. Subsurface geological structures provide large potential capacities for energy stored in the form of heat or gas on daily to seasonal time scales. In order to explore this potential sustainably, the possible induced effects of energy storage operations have to be quantified for both specified normal operation and events of failure. The ANGUS+ project therefore integrates experimental laboratory studies with numerical approaches to assess subsurface energy storage scenarios and monitoring methods. Subsurface storage options for gas, i.e. hydrogen, synthetic methane and compressed air in salt caverns or porous structures, as well as subsurface heat storage are investigated with respect to site prerequisites, storage dimensions, induced effects, monitoring methods and integration into spatial planning schemes. The conceptual interdisciplinary approach of the ANGUS+ project towards the integration of subsurface energy storage into a sustainable subsurface planning scheme is presented here, and this approach is then demonstrated using the examples of two selected energy storage options: Firstly, the option of seasonal heat storage in a shallow aquifer is presented. Coupled thermal and hydraulic processes induced by periodic heat injection and extraction were simulated in the open-source numerical modelling package OpenGeoSys. Situations of specified normal operation as well as cases of failure in operational storage with leaking heat transfer fluid are considered. Bench-scale experiments provided parameterisations of temperature dependent changes in shallow groundwater hydrogeochemistry. As a second example, the option of seasonal hydrogen storage in a deep saline aquifer is considered. The induced thermal and hydraulic multiphase flow processes were simulated. Also, an integrative approach towards geophysical monitoring of gas presence was evaluated by synthetically applying these monitoring methods to the synthetic, however realistically defined numerical storage scenarios. Laboratory experiments provided parameterisations of geochemical effects caused by storage gas leakage into shallow aquifers in cases of sealing failure. Ultimately, the analysis of realistically defined scenarios of subsurface energy storage within the ANGUS+ project allows a quantification of the subsurface space claimed by a storage operation and its induced effects. Acknowledgments: This work is part of the ANGUS+ project (www.angusplus.de) and funded by the German Federal Ministry of Education and Research (BMBF) as part of the energy storage initiative "Energiespeicher".

Preliminary Pseudo 3-D Imagery of the State Line Fault, Stewart Valley, Nevada Using Seismic Reflection Data

NASA Astrophysics Data System (ADS)

Saldaña, S. C.; Snelson, C. M.; Taylor, W. J.; Beachly, M.; Cox, C. M.; Davis, R.; Stropky, M.; Phillips, R.; Robins, C.; Cothrun, C.

2007-12-01

The Pahrump Fault system is located in the central Basin and Range region and consists of three main fault zones: the Nopah range front fault zone, the State Line fault zone and the Spring Mountains range fault zone. The State Line fault zone is made up north-west trending dextral strike-slip faults that run parallel to the Nevada- California border. Previous geologic and geophysical studies conducted in and around Stewart Valley, located ~90 km from Las Vegas, Nevada, have constrained the location of the State Line fault zone to within a few kilometers. The goals of this project were to use seismic methods to definitively locate the northwestern most trace of the State Line fault and produce pseudo 3-D seismic cross-sections that can then be used to characterize the subsurface geometry and determine the slip of the State Line fault. During July 2007, four seismic lines were acquired in Stewart Valley: two normal and two parallel to the mapped traces of the State Line fault. Presented here are preliminary results from the two seismic lines acquired normal to the fault. These lines were acquired utilizing a 144-channel geode system with each of the 4.5 Hz vertical geophones set out at 5 m intervals to produce a 595 m long profile to the north and a 715 m long profile to the south. The vibroseis was programmed to produce an 8 s linear sweep from 20-160 Hz. These data returned excellent signal to noise and reveal subsurface lithology that will subsequently be used to resolve the subsurface geometry of the State Line fault. This knowledge will then enhance our understanding of the evolution of the State Line fault. Knowing how the State Line fault has evolved gives insight into the stick-slip fault evolution for the region and may improve understanding of how stress has been partitioned from larger strike-slip systems such as the San Andreas fault.

Microbial Ecosystems from the Deepest Regions of the Terrestrial Deep Biosphere

NASA Astrophysics Data System (ADS)

Moser, D. P.

2011-12-01

Although recent discoveries from four continents support the existence of microbial ecosystems across vast regions of our planet's inner space, very little is known about the abundance, distribution, diversity, or ultimate depth limit of subsurface microbial life. These deep lithospheric inhabitants must contend with a variety of potential challenges including high temperature, pressure and salinity, extreme isolation, and low energy flux. Interestingly, although deep microbial ecosystems are assumed to be energy and nutrient limited, it is often difficult to identify any one limiting substrate and the energy for deep life is often present in relative abundance (e.g. as geologically-produced hydrogen or other reduced gases). Recently, the concept of radiation-supported deep microbial ecosystems has gained traction in the literature. In particular, one bacterium, a Firmicute denoted Candidatus Desulforudis audaxviator, has been shown to be prominent, and in cases dominate, in deep fracture fluids from across the Witwatersrand basin of South Africa, where it appears to persist by utilizing H2 and SO42- derived from radiochemical reactions in U-rich host rock. Until recently, these mines were thought to define the geographic limit of this genus and species; however, our recent North American detection of D. audaxviator in radioactive subsurface water resulting from underground nuclear tests both supports earlier assertions concerning the radiochemical lifestyle of D. audaxviator and greatly expands its range. Results such as these suggest that novel modes of life operating without inputs from the photosphere are possible, and thus may have implications for the likelihood of detecting life off the Earth (e.g. in the Martian subsurface). In addition to underground nuclear detonation cavities, this talk will consider insights gained from ongoing microbial ecology assessments from several to date unexplored deep ecosystems accessed via deep mines in the Black Hills (USA) and Canadian Shield (Canada) and exploratory boreholes in the Southern Great Basin (USA). The tantalizing possibility that several of these new potential habitats have exceeded some limit for life will be also be explored.

Reactivation of Deep Subsurface Microbial Community in Response to Methane or Methanol Amendment

PubMed Central

Rajala, Pauliina; Bomberg, Malin

2017-01-01

Microbial communities in deep subsurface environments comprise a large portion of Earth’s biomass, but the microbial activity in these habitats is largely unknown. Here, we studied how microorganisms from two isolated groundwater fractures at 180 and 500 m depths of the Outokumpu Deep Drillhole (Finland) responded to methane or methanol amendment, in the presence or absence of sulfate as an additional electron acceptor. Methane is a plausible intermediate in the deep subsurface carbon cycle, and electron acceptors such as sulfate are critical components for oxidation processes. In fact, the majority of the available carbon in the Outokumpu deep biosphere is present as methane. Methanol is an intermediate of methane oxidation, but may also be produced through degradation of organic matter. The fracture fluid samples were incubated in vitro with methane or methanol in the presence or absence of sulfate as electron acceptor. The metabolic response of microbial communities was measured by staining the microbial cells with fluorescent redox sensitive dye combined with flow cytometry, and DNA or cDNA-derived amplicon sequencing. The microbial community of the fracture zone at the 180 m depth was originally considerably more respiratory active and 10-fold more numerous (105 cells ml-1 at 180 m depth and 104 cells ml-1 at 500 m depth) than the community of the fracture zone at the 500 m. However, the dormant microbial community at the 500 m depth rapidly reactivated their transcription and respiration systems in the presence of methane or methanol, whereas in the shallower fracture zone only a small sub-population was able to utilize the newly available carbon source. In addition, the composition of substrate activated microbial communities differed at both depths from original microbial communities. The results demonstrate that OTUs representing minor groups of the total microbial communities play an important role when microbial communities face changes in environmental conditions. PMID:28367144

Novel Degenerate PCR Method for Whole-Genome Amplification Applied to Peru Margin (ODP Leg 201) Subsurface Samples

PubMed Central

Martino, Amanda J.; Rhodes, Matthew E.; Biddle, Jennifer F.; Brandt, Leah D.; Tomsho, Lynn P.; House, Christopher H.

2011-01-01

A degenerate polymerase chain reaction (PCR)-based method of whole-genome amplification, designed to work fluidly with 454 sequencing technology, was developed and tested for use on deep marine subsurface DNA samples. While optimized here for use with Roche 454 technology, the general framework presented may be applicable to other next generation sequencing systems as well (e.g., Illumina, Ion Torrent). The method, which we have called random amplification metagenomic PCR (RAMP), involves the use of specific primers from Roche 454 amplicon sequencing, modified by the addition of a degenerate region at the 3′ end. It utilizes a PCR reaction, which resulted in no amplification from blanks, even after 50 cycles of PCR. After efforts to optimize experimental conditions, the method was tested with DNA extracted from cultured E. coli cells, and genome coverage was estimated after sequencing on three different occasions. Coverage did not vary greatly with the different experimental conditions tested, and was around 62% with a sequencing effort equivalent to a theoretical genome coverage of 14.10×. The GC content of the sequenced amplification product was within 2% of the predicted values for this strain of E. coli. The method was also applied to DNA extracted from marine subsurface samples from ODP Leg 201 site 1229 (Peru Margin), and results of a taxonomic analysis revealed microbial communities dominated by Proteobacteria, Chloroflexi, Firmicutes, Euryarchaeota, and Crenarchaeota, among others. These results were similar to those obtained previously for those samples; however, variations in the proportions of taxa identified illustrates well the generally accepted view that community analysis is sensitive to both the amplification technique used and the method of assigning sequences to taxonomic groups. Overall, we find that RAMP represents a valid methodology for amplifying metagenomes from low-biomass samples. PMID:22319519

Kerogen extraction from subterranean oil shale resources

DOEpatents

Looney, Mark Dean; Lestz, Robert Steven; Hollis, Kirk; Taylor, Craig; Kinkead, Scott; Wigand, Marcus

2010-09-07

The present invention is directed to methods for extracting a kerogen-based product from subsurface (oil) shale formations, wherein such methods rely on fracturing and/or rubblizing portions of said formations so as to enhance their fluid permeability, and wherein such methods further rely on chemically modifying the shale-bound kerogen so as to render it mobile. The present invention is also directed at systems for implementing at least some of the foregoing methods. Additionally, the present invention is also directed to methods of fracturing and/or rubblizing subsurface shale formations and to methods of chemically modifying kerogen in situ so as to render it mobile.

Kerogen extraction from subterranean oil shale resources

DOEpatents

Looney, Mark Dean [Houston, TX; Lestz, Robert Steven [Missouri City, TX; Hollis, Kirk [Los Alamos, NM; Taylor, Craig [Los Alamos, NM; Kinkead, Scott [Los Alamos, NM; Wigand, Marcus [Los Alamos, NM

2009-03-10

The present invention is directed to methods for extracting a kerogen-based product from subsurface (oil) shale formations, wherein such methods rely on fracturing and/or rubblizing portions of said formations so as to enhance their fluid permeability, and wherein such methods further rely on chemically modifying the shale-bound kerogen so as to render it mobile. The present invention is also directed at systems for implementing at least some of the foregoing methods. Additionally, the present invention is also directed to methods of fracturing and/or rubblizing subsurface shale formations and to methods of chemically modifying kerogen in situ so as to render it mobile.

Groundwater Salinity Simulation of a Subsurface Reservoir in Taiwan

NASA Astrophysics Data System (ADS)

Fang, H. T.

2015-12-01

The subsurface reservoir is located in Chi-Ken Basin, Pescadores (a group islands located at western part of Taiwan). There is no river in these remote islands and thus the freshwater supply is relied on the subsurface reservoir. The basin area of the subsurface reservoir is 2.14 km2 , discharge of groundwater is 1.27×106m3 , annual planning water supplies is 7.9×105m3 , which include for domestic agricultural usage. The annual average temperature is 23.3oC, average moisture is 80~85%, annual average rainfall is 913 mm, but ET rate is 1975mm. As there is no single river in the basin; the major recharge of groundwater is by infiltration. Chi-Ken reservoir is the first subsurface reservoir in Taiwan. Originally, the water quality of the reservoir is good. The reservoir has had the salinity problem since 1991 and it became more and more serious from 1992 until 1994. Possible reason of the salinity problem was the shortage of rainfall or the leakage of the subsurface barrier which caused the seawater intrusion. The present study aimed to determine the leakage position of subsurface barrier that caused the salinity problem. In order to perform the simulation for different possible leakage position of the subsurface reservoir, a Groundwater Modeling System (GMS) is used to define soils layer data, hydro-geological parameters, initial conditions, boundary conditions and the generation of three dimension meshes. A three dimension FEMWATER(Yeh , 1996) numerical model was adopted to find the possible leakage position of the subsurface barrier and location of seawater intrusion by comparing the simulation of different possible leakage with the observations. 1.By assuming the leakage position in the bottom of barrier, the simulated numerical result matched the observation better than the other assumed leakage positions. It showed that the most possible leakage position was at the bottom of the barrier. 2.The research applied three dimension FEMWATER and GMS as an interface to input parameter. The simulation of water level and chloride concentration already showed the real situation, and the result can be applied to the future study of the Chi-Ken subsurface reservoir salinity problems.

Entropy-Based Classification of Subsurface Scatterers: A Valuable Tool for the Analysis of Data Obtained by the Fully Polarimetric WISDOM Radar

NASA Astrophysics Data System (ADS)

Plettemeier, D.; Statz, C.; Hahnel, R.; Benedix, W. S.; Hamran, S. E.; Ciarletti, V.

2016-12-01

The "Water Ice Subsurface Deposition on Mars" Experiment (WISDOM) is a Ground Penetrating Radar (GPR) and part of the 2020 ExoMars Rover payload. It will be the first GPR operating on a planetary rover and the first fully polarimetric radar tasked at probing the subsurface of Mars. WISDOM operates at frequencies between 500 MHz and 3 GHz yielding a centimetric resolution and a penetration depth of about 3 meters in Martian soil. Its prime scientific objective is the detailed characterization of the material distribution within the first few meters of the Martian subsurface as a contribution to the search for evidence of past life. For the first time, WISDOM will give access to the geological structure, electromagnetic nature, and hydrological state of the shallow subsurface by retrieving the layering and properties of the buried reflectors at an unprecedented resolution and, due to the fully polarimetric measurements, amount of information. Furthermore, a "real time" subsurface analysis will support the drill operations by identifying locations of high scientific interest and low risk. Key element in the WISDOM data analysis is the fast and reliable classification and correct localization of subsurface scatterers and layers. The fully polarimetric nature of the WISDOM measurements allows the use of the entropy-alpha decomposition (H-alpha). This method enables the classification of reconstructed images of the subsurface (obtained by inverse imaging algorithms, e.g. f-k migration) with regard to the main scattering mechanisms of geological features present in the image of the subsurface. It is, for example, possible to differentiate smooth surfaces, rough surfaces, isolated spherical scatterers, double- and bounce scattering, anisotropic scatterers, clouds of small scatterers of similar shape as well as layers of oblate spheroids. Preliminary tests under laboratory conditions suggest the feasibility and value of the approach for the classification of geological features in the Martian subsurface in the context of WISDOM data processing and operations. It is a fast and reliable tool leveraging the whole amount of information provided by the fully polarimetric WISDOM Radar.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Jitendra; Collier, Nathan; Bisht, Gautam

Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to the atmosphere under warming climate scenarios. Ice-wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. This microtopography plays a critical role in regulating the fine-scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behavior under the current as well as changing climate. Here, we present an end-to-end effort for high-resolution numerical modeling of thermal hydrology at real-world fieldmore » sites, utilizing the best available data to characterize and parameterize the models. We also develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites near Barrow, Alaska, spanning across low to transitional to high-centered polygons, representing a broad polygonal tundra landscape. A multiphase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using a high-resolution lidar digital elevation model (DEM), microtopographic features of the landscape were characterized and represented in the high-resolution model mesh. The best available soil data from field observations and literature were utilized to represent the complex heterogeneous subsurface in the numerical model. Simulation results demonstrate the ability of the developed modeling approach to capture – without recourse to model calibration – several aspects of the complex thermal regimes across the sites, and provide insights into the critical role of polygonal tundra microtopography in regulating the thermal dynamics of the carbon-rich permafrost soils. Moreover, areas of significant disagreement between model results and observations highlight the importance of field-based observations of soil thermal and hydraulic properties for modeling-based studies of permafrost thermal dynamics, and provide motivation and guidance for future observations that will help address model and data gaps affecting our current understanding of the system.« less

Using Distributed Fiber Optic Sensing to Monitor Large Scale Permafrost Transitions: Preliminary Results from a Controlled Thaw Experiment

NASA Astrophysics Data System (ADS)

Ajo Franklin, J. B.; Wagner, A. M.; Lindsey, N.; Dou, S.; Bjella, K.; Daley, T. M.; Freifeld, B. M.; Ulrich, C.; Gelvin, A.; Morales, A.; James, S. R.; Saari, S.; Ekblaw, I.; Wood, T.; Robertson, M.; Martin, E. R.

2016-12-01

In a warming world, permafrost landscapes are being rapidly transformed by thaw, yielding surface subsidence and groundwater flow alteration. The same transformations pose a threat to arctic infrastructure and can induce catastrophic failure of the roads, runways, and pipelines on which human habitation depends. Scalable solutions to monitoring permafrost thaw dynamics are required to both quantitatively understand biogeochemical feedbacks as well as to protect built infrastructure from damage. Unfortunately, permafrost alteration happens over the time scale of climate change, years to decades, a decided challenge for testing new sensing technologies in a limited context. One solution is to engineer systems capable of rapidly thawing large permafrost units to allow short duration experiments targeting next-generation sensing approaches. We present preliminary results from a large-scale controlled permafrost thaw experiment designed to evaluate the utility of different geophysical approaches for tracking the cause, precursors, and early phases of thaw subsidence. We focus on the use of distributed fiber optic sensing for this challenge and deployed distributed temperature (DTS), strain (DSS), and acoustic (DAS) sensing systems in a 2D array to detect thaw signatures. A 10 x 15 x 1 m section of subsurface permafrost was heated using an array of 120 downhole heaters (60 w) at an experimental site near Fairbanks, AK. Ambient noise analysis of DAS datasets collected at the plot, coupled to shear wave inversion, was utilized to evaluate changes in shear wave velocity associated with heating and thaw. These measurements were confirmed by seismic surveys collected using a semi-permanent orbital seismic source activated on a daily basis. Fiber optic measurements were complemented by subsurface thermistor and thermocouple arrays, timelapse total station surveys, LIDAR, secondary seismic measurements (geophone and broadband recordings), timelapse ERT, borehole NMR, soil moisture measurements, hydrologic measurements, and multi-angle photogrammetry. This unusually dense combination of measurement techniques provides an excellent opportunity to characterize the geophysical signatures of permafrost thaw in a controlled environment.

Impact and intrusion of the foot of a lizard running rapidly on sand

NASA Astrophysics Data System (ADS)

Li, Chen; Hsieh, Tonia; Umbanhowar, Paul; Goldman, Daniel

2012-11-01

The desert-dwelling zebra-tailed lizard (Callisaurus draconoides, 10 cm, 10 g) runs rapidly (~10 BL/s) on granular media (GM) like sand and gravel. On loosely packed GM, its large hind feet penetrate into the substrate during each step. Based on above-ground observation, a previous study (Li et al., JEB 2012) hypothesized that the hind foot rotated in the vertical plane subsurface to generate lift. To explain the observed center-of-mass dynamics, the model assumed that ground reaction force was dominated by speed-independent frictional drag. Here we use x-ray high speed video to obtain subsurface foot kinematics of the lizard running on GM, which confirms the hypothesized subsurface foot rotation following rapid foot impact at touchdown. However, using impact force measurements, a resistive force model, and the observed foot kinematics, we find that impact force during initial foot touchdown and speed-independent frictional drag during rotation only account for part of the required lift to support locomotion. This suggests that the rapid foot rotation further allows the lizard to utilize inertial forces from the local acceleration of the substrate (particles), similar to small robots running on GM (Qian et al., RSS 2012) and the basilisk (Jesus) lizard running on water.

Bacterial community structure and dissolved organic matter in repeatedly flooded subsurface karst water pools.

PubMed

Shabarova, Tanja; Villiger, Jörg; Morenkov, Oleg; Niggemann, Jutta; Dittmar, Thorsten; Pernthaler, Jakob

2014-07-01

Bacterial diversity, community assembly, and the composition of the dissolved organic matter (DOM) were studied in three temporary subsurface karst pools with different flooding regimes. We tested the hypothesis that microorganisms introduced to the pools during floods faced environmental filtering toward a 'typical' karst water community, and we investigated whether DOM composition was related to floodings and the residence time of water in stagnant pools. As predicted, longer water residence consistently led to a decline of bacterial diversity. The microbial assemblages in the influx water harbored more 'exotic' lineages with large distances to known genotypes, yet these initial communities already appeared to be shaped by selective processes. β-Proteobacterial operational taxonomic units (OTUs) closely related to microbes from subsurface or surface aquatic environments were mainly responsible for the clustering of samples according to water residence time in the pools. By contrast, several Cytophagaceae and Flavobacteriaceae OTUs were related to different floodings, which were also the main determinants of DOM composition. A subset of compounds distinguishable by molecular mass and O/C content were characteristic for individual floods. Moreover, there was a transformation of DOM in stagnant pools toward smaller and more aromatic compounds, potentially also reflecting microbial utilization. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Photoacoustic microscopy of human teeth

NASA Astrophysics Data System (ADS)

Rao, Bin; Cai, Xin; Favazza, Christopher; Yao, Junjie; Li, Li; Duong, Steven; Liaw, Lih-Huei; Holtzman, Jennifer; Wilder-Smith, Petra; Wang, Lihong V.

2011-03-01

Photoacoustic microscopy (PAM) utilizes short laser pulses to deposit energy into light absorbers and sensitively detects the ultrasonic waves the absorbers generate in response. PAM directly renders a three-dimensional spatial distribution of sub-surface optical absorbers. Unlike other optical imaging technologies, PAM features label-free optical absorption contrast and excellent imaging depths. Standard dental imaging instruments are limited to X-ray and CCD cameras. Subsurface optical dental imaging is difficult due to the highly-scattering enamel and dentin tissue. Thus, very few imaging methods can detect dental decay or diagnose dental pulp, which is the innermost part of the tooth, containing the nerves, blood vessels, and other cells. Here, we conducted a feasibility study on imaging dental decay and dental pulp with PAM. Our results showed that PAM is sensitive to the color change associated with dental decay. Although the relative PA signal distribution may be affected by surface contours and subsurface reflections from deeper dental tissue, monitoring changes in the PA signals (at the same site) over time is necessary to identify the progress of dental decay. Our results also showed that deep-imaging, near-infrared (NIR) PAM can sensitively image blood in the dental pulp of an in vitro tooth. In conclusion, PAM is a promising tool for imaging both dental decay and dental pulp.

The Prediction-Focused Approach: An opportunity for hydrogeophysical data integration and interpretation

NASA Astrophysics Data System (ADS)

Hermans, Thomas; Nguyen, Frédéric; Klepikova, Maria; Dassargues, Alain; Caers, Jef

2017-04-01

Hydrogeophysics is an interdisciplinary field of sciences aiming at a better understanding of subsurface hydrological processes. If geophysical surveys have been successfully used to qualitatively characterize the subsurface, two important challenges remain for a better quantification of hydrological processes: (1) the inversion of geophysical data and (2) their integration in hydrological subsurface models. The classical inversion approach using regularization suffers from spatially and temporally varying resolution and yields geologically unrealistic solutions without uncertainty quantification, making their utilization for hydrogeological calibration less consistent. More advanced techniques such as coupled inversion allow for a direct use of geophysical data for conditioning groundwater and solute transport model calibration. However, the technique is difficult to apply in complex cases and remains computationally demanding to estimate uncertainty. In a recent study, we investigate a prediction-focused approach (PFA) to directly estimate subsurface physical properties from geophysical data, circumventing the need for classic inversions. In PFA, we seek a direct relationship between the data and the subsurface variables we want to predict (the forecast). This relationship is obtained through a prior set of subsurface models for which both data and forecast are computed. A direct relationship can often be derived through dimension reduction techniques. PFA offers a framework for both hydrogeophysical "inversion" and hydrogeophysical data integration. For hydrogeophysical "inversion", the considered forecast variable is the subsurface variable, such as the salinity. An ensemble of possible solutions is generated, allowing uncertainty quantification. For hydrogeophysical data integration, the forecast variable becomes the prediction we want to make with our subsurface models, such as the concentration of contaminant in a drinking water production well. Geophysical and hydrological data are combined to derive a direct relationship between data and forecast. We illustrate the process for the design of an aquifer thermal energy storage (ATES) system. An ATES system can theoretically recover in winter the heat stored in the aquifer during summer. In practice, the energy efficiency is often lower than expected due to spatial heterogeneity of hydraulic properties combined to a non-favorable hydrogeological gradient. A proper design of ATES systems should consider the uncertainty of the prediction related to those parameters. With a global sensitivity analysis, we identify sensitive parameters for heat storage prediction and validate the use of a short term heat tracing experiment monitored with geophysics to generate informative data. First, we illustrate how PFA can be used to successfully derive the distribution of temperature in the aquifer from ERT during the heat tracing experiment. Then, we successfully integrate the geophysical data to predict medium-term heat storage in the aquifer using PFA. The result is a full quantification of the posterior distribution of the prediction conditioned to observed data in a relatively limited time budget.

Association between mean and interannual equatorial Indian Ocean subsurface temperature bias in a coupled model

NASA Astrophysics Data System (ADS)

Srinivas, G.; Chowdary, Jasti S.; Gnanaseelan, C.; Prasad, K. V. S. R.; Karmakar, Ananya; Parekh, Anant

2018-03-01

In the present study the association between mean and interannual subsurface temperature bias over the equatorial Indian Ocean (EIO) is investigated during boreal summer (June through September; JJAS) in the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFSv2) hindcast. Anomalously high subsurface warm bias (greater than 3 °C) over the eastern EIO (EEIO) region is noted in CFSv2 during summer, which is higher compared to other parts of the tropical Indian Ocean. Prominent eastward current bias in the upper 100 m over the EIO region induced by anomalous westerly winds is primarily responsible for subsurface temperature bias. The eastward currents transport warm water to the EEIO and is pushed down to subsurface due to downwelling. Thus biases in both horizontal and vertical currents over the EIO region support subsurface warm bias. The evolution of systematic subsurface warm bias in the model shows strong interannual variability. These maximum subsurface warming episodes over the EEIO are mainly associated with La Niña like forcing. Strong convergence of low level winds over the EEIO and Maritime continent enhanced the westerly wind bias over the EIO during maximum warming years. This low level convergence of wind is induced by the bias in the gradient in the mean sea level pressure with positive bias over western EIO and negative bias over EEIO and parts of western Pacific. Consequently, changes in the atmospheric circulation associated with La Niña like conditions affected the ocean dynamics by modulating the current bias thereby enhancing the subsurface warm bias over the EEIO. It is identified that EEIO subsurface warming is stronger when La Niña co-occurred with negative Indian Ocean Dipole events as compared to La Niña only years in the model. Ocean general circulation model (OGCM) experiments forced with CFSv2 winds clearly support our hypothesis that ocean dynamics influenced by westerly winds bias is primarily responsible for the strong subsurface warm bias over the EEIO. This study advocates the importance of understanding the ability of the models in representing the large scale air-sea interactions over the tropics and their impact on ocean biases for better monsoon forecast.

Subsurface Monitoring of CO2 Sequestration - A Review and Look Forward

NASA Astrophysics Data System (ADS)

Daley, T. M.

2012-12-01

The injection of CO2 into subsurface formations is at least 50 years old with large-scale utilization of CO2 for enhanced oil recovery (CO2-EOR) beginning in the 1970s. Early monitoring efforts had limited measurements in available boreholes. With growing interest in CO2 sequestration beginning in the 1990's, along with growth in geophysical reservoir monitoring, small to mid-size sequestration monitoring projects began to appear. The overall goals of a subsurface monitoring plan are to provide measurement of CO2 induced changes in subsurface properties at a range of spatial and temporal scales. The range of spatial scales allows tracking of the location and saturation of the plume with varying detail, while finer temporal sampling (up to continuous) allows better understanding of dynamic processes (e.g. multi-phase flow) and constraining of reservoir models. Early monitoring of small scale pilots associated with CO2-EOR (e.g., the McElroy field and the Lost Hills field), developed many of the methodologies including tomographic imaging and multi-physics measurements. Large (reservoir) scale sequestration monitoring began with the Sleipner and Weyburn projects. Typically, large scale monitoring, such as 4D surface seismic, has limited temporal sampling due to costs. Smaller scale pilots can allow more frequent measurements as either individual time-lapse 'snapshots' or as continuous monitoring. Pilot monitoring examples include the Frio, Nagaoka and Otway pilots using repeated well logging, crosswell imaging, vertical seismic profiles and CASSM (continuous active-source seismic monitoring). For saline reservoir sequestration projects, there is typically integration of characterization and monitoring, since the sites are not pre-characterized resource developments (oil or gas), which reinforces the need for multi-scale measurements. As we move beyond pilot sites, we need to quantify CO2 plume and reservoir properties (e.g. pressure) over large scales, while still obtaining high resolution. Typically the high-resolution (spatial and temporal) tools are deployed in permanent or semi-permanent borehole installations, where special well design may be necessary, such as non-conductive casing for electrical surveys. Effective utilization of monitoring wells requires an approach of modular borehole monitoring (MBM) were multiple measurements can be made. An example is recent work at the Citronelle pilot injection site where an MBM package with seismic, fluid sampling and distributed fiber sensing was deployed. For future large scale sequestration monitoring, an adaptive borehole-monitoring program is proposed.

Depth Distribution and Assembly of Sulfate-Reducing Microbial Communities in Marine Sediments of Aarhus Bay

PubMed Central

Jochum, Lara M.; Chen, Xihan; Lever, Mark A.; Loy, Alexander; Jørgensen, Bo Barker; Schramm, Andreas

2017-01-01

ABSTRACT Most sulfate-reducing microorganisms (SRMs) present in subsurface marine sediments belong to uncultured groups only distantly related to known SRMs, and it remains unclear how changing geochemical zones and sediment depth influence their community structure. We mapped the community composition and abundance of SRMs by amplicon sequencing and quantifying the dsrB gene, which encodes dissimilatory sulfite reductase subunit beta, in sediment samples covering different vertical geochemical zones ranging from the surface sediment to the deep sulfate-depleted subsurface at four locations in Aarhus Bay, Denmark. SRMs were present in all geochemical zones, including sulfate-depleted methanogenic sediment. The biggest shift in SRM community composition and abundance occurred across the transition from bioturbated surface sediments to nonbioturbated sediments below, where redox fluctuations and the input of fresh organic matter due to macrofaunal activity are absent. SRM abundance correlated with sulfate reduction rates determined for the same sediments. Sulfate availability showed a weaker correlation with SRM abundances and no significant correlation with the composition of the SRM community. The overall SRM species diversity decreased with depth, yet we identified a subset of highly abundant community members that persists across all vertical geochemical zones of all stations. We conclude that subsurface SRM communities assemble by the persistence of members of the surface community and that the transition from the bioturbated surface sediment to the unmixed sediment below is a main site of assembly of the subsurface SRM community. IMPORTANCE Sulfate-reducing microorganisms (SRMs) are key players in the marine carbon and sulfur cycles, especially in coastal sediments, yet little is understood about the environmental factors controlling their depth distribution. Our results suggest that macrofaunal activity is a key driver of SRM abundance and community structure in marine sediments and that a small subset of SRM species of high relative abundance in the subsurface SRM community persists from the sulfate-rich surface sediment to sulfate-depleted methanogenic subsurface sediment. More generally, we conclude that SRM communities inhabiting the subsurface seabed assemble by the selective survival of members of the surface community. PMID:28939599

Near Real-Time Prospecting for Lunar Volatiles: Demonstrating RESOLVE Science in the Field

NASA Astrophysics Data System (ADS)

Elphic, R. C.; Colaprete, A.; Heldmann, J. L.; Mattes, G.; Ennico, K.; Sanders, G. B.; Quinn, J.; Fritzler, E.; Marinova, M.; Roush, T. L.; Stoker, C.; Larson, W.; Picard, M.; McMurray, R.; Morse, S.

2012-12-01

The Regolith and Environment Science and Oxygen & Lunar Volatile Extraction (RESOLVE) project aims to demonstrate the utility of "in situ resource utilization". In situ resource utilization (ISRU) is a way to rebalance the economics of spaceflight by reducing or eliminating materials that must be brought up from Earth and placed on the surface of the Moon for human use. RESOLVE is developing a rover-borne payload that (1) can locate near subsurface volatiles, (2) excavate and analyze samples of the volatile-bearing regolith, and (3) demonstrate the form, extractability and usefulness of the materials. Such investigations are important not only for ISRU but are also critically important for understanding the scientific nature of these intriguing lunar polar volatile deposits. Temperature models and orbital data suggest near surface volatile concentrations may exist at briefly lit lunar polar locations outside persistently shadowed regions. A lunar rover could be remotely operated at some of these locations for the 4-7 days of expected sunlight at relatively low cost. In July 2012 the RESOLVE project conducted a full-scale field demonstration. In particular, the ability to perform the real-time measurement analysis necessary to search for volatiles and the ability to combine the various measurement techniques to meet the mission measurement and science goals. With help from the Pacific International Space Center for Exploration Systems (PISCES), a lunar rover prototype (provided by the Canadian Space Agency) was equipped with prospecting instruments (neutron spectrometer and near-infrared spectrometer), subsurface access and sampling tools, including both an auger and coring drill (provided by CSA) and subsurface sample analysis instrumentation, including a sample oven system, the Oxygen and Volatile Extraction Node (OVEN), and Gas Chromatograph / Mass Spectrometer system, the Lunar Advanced Volatile Analysis (LAVA) system. Given the relatively short time period this lunar mission is being designed to, prospecting needs to occur in near real-time. The two prospecting instruments are the neutron and NIR spectrometers. In the field demo a small radioactive source was provided the neutron flux. The NIR spectrometer, which includes its own light source, looks at surface reflectance for signatures of bound H2O/OH and general mineralogy. Once a "hot spot" was found by the prospecting instruments, the drill could either auger or core. The auger drill worked to a depth of 50 cm and is monitored with a drill camera and the NIR spectrometer. As cuttings are brought up the NIR spectra is monitored. If a particular location is considered of high-interest then the decision to core could be made. The coring drill (a push-tube) allowed a 1-meter sample to be acquired processed by the OVEN/LAVA sys-tem. This presentation will provide details as how these instruments worked together and how and if the planned measurements and science was obtained.

Near Real Time Prospecting for Lunar Volatiles: Demonstrating RESOLVE Science in the Field

NASA Technical Reports Server (NTRS)

Elphic, Richard; Colaprete, Anthony; Heldmann, Jennifer; Mattes, Gregory W.; Ennico, Kimberly; Sanders, Gerald; Quinn, Jacqueline; Tegnerud, Erin Leigh; Marinova, Margarita; Larson, William E.;

Structural adjustment for accurate conditioning in large-scale subsurface systems

NASA Astrophysics Data System (ADS)

Tahmasebi, Pejman

2017-03-01

Most of the current subsurface simulation approaches consider a priority list for honoring the well and any other auxiliary data, and eventually adopt a middle ground between the quality of the model and conditioning it to hard data. However, as the number of datasets increases, such methods often produce undesirable features in the subsurface model. Due to their high flexibility, subsurface modeling based on training images (TIs) is becoming popular. Providing comprehensive TIs remains, however, an outstanding problem. In addition, identifying a pattern similar to those in the TI that honors the well and other conditioning data is often difficult. Moreover, the current subsurface modeling approaches do not account for small perturbations that may occur in a subsurface system. Such perturbations are active in most of the depositional systems. In this paper, a new methodology is presented that is based on an irregular gridding scheme that accounts for incomplete TIs and minor offsets. Use of the methodology enables one to use a small or incomplete TI and adaptively change the patterns in the simulation grid in order to simultaneously honor the well data and take into account the effect of the local offsets. Furthermore, the proposed method was used on various complex process-based models and their structures are deformed for matching with the conditioning point data. The accuracy and robustness of the proposed algorithm are successfully demonstrated by applying it to models of several complex examples.

Idaho National Laboratory Vadose Zone Research Park Geohydrological Monitoring Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristine Baker

2006-01-01

Vadose zone lithology, hydrological characterization of interbed sediments, and hydrological data from subsurface monitoring of Idaho Nuclear Technology and Engineering Center wastewater infiltration are presented. Three-dimensional subsurface lithology of the vadose zone beneath the Vadose Zone Research Park is represented in a 2 dimensional (2 D) diagram showing interpolated lithology between monitoring wells. Laboratory-measured values for saturated hydraulic conductivity and porosity are given for three major interbeds, denoted as the B BC interbed (20 to 35 m bls), the C D interbed (40 to 45 m bls), and the DE 1 2 interbed (55 to 65 m bls), along withmore » an overall physical description of the sediments and geologic depositional environments. Pre-operational pore water pressure conditions are presented to show the presence and location of perched water zones before pond discharge at the New Percolation Ponds. Subsurface infiltration conditions during initial high-volume discharge are presented to show water arrival times and arrival sequences. Steady-state conditions are then presented to show formation and locations of perched water zones and recharge sources after several months of discharge to the New Percolation Ponds.« less

The Dual Role of Vegetation as a Constraint on Mass and Energy Flux into the Critical Zone and as an Emergent Property of Geophysical Critical Zone Structure

NASA Astrophysics Data System (ADS)

Brooks, P. D.; Swetnam, T. L.; Barnard, H. R.; Singha, K.; Harpold, A.; Litvak, M. E.

2017-12-01

Spatial patterns in vegetation long have been used to scale both landsurface-atmosphere exchanges of water and carbon as well as to infer subsurface structure. These pursuits typical proceed in isolation and rarely do inferences gained from one community propagate to related efforts in another. Perhaps more importantly, vegetation often is treated as an emergent property of landscape-climate interactions rather than an active modifier of both critical zone structure and energy fluxes. We posit that vegetation structure and activity are under utilized as a tool towards understanding landscape evolution and present examples that begin to disentangle the role of vegetation as both an emergent property and an active control on critical zone structure and function. As climate change, population growth, and land use changes threaten water resources worldwide, the need for the new insights vegetation can provide becomes not just a basic science priority, but a pressing applied science question with clear societal importance. This presentation will provide an overview of recent efforts to address the dual role of vegetation in both modifying and reflecting critical zone structure in the western North American forests. For example, interactions between topography and stand scale vegetation structure influence both solar radiation and turbulence altering landscape scale partitioning of evaporation vs transpiration with major impacts of surface water supply. Similarly, interactions between topographic shading, lateral redistribution of plant available water, and subsurface storage create a mosaic of drought resistance and resilience across complex terrain. These complex interactions between geophysical and vegetation components of critical zone structure result in predictable patterns in catchment scale hydrologic partitioning within individual watersheds while simultaneously suggesting testable hypotheses for why catchments under similar climate regimes respond so differently to drought stress.

Development of a direct push based in-situ thermal conductivity measurement system

NASA Astrophysics Data System (ADS)

Chirla, Marian Andrei; Vienken, Thomas; Dietrich, Peter; Bumberger, Jan

2016-04-01

Heat pump systems are commonly utilized in Europe, for the exploitation of the shallow geothermal potential. To guarantee a sustainable use of the geothermal heat pump systems by saving resources and minimizing potential negative impacts induced by temperature changes within soil and groundwater, new geothermal exploration methods and tools are required. The knowledge of the underground thermal properties is a necessity for a correct and optimum design of borehole heat exchangers. The most important parameter that indicates the performance of the systems is thermal conductivity of the ground. Mapping the spatial variability of thermal conductivity, with high resolution in the shallow subsurface for geothermal purposes, requires a high degree of technical effort to procure adequate samples for thermal analysis. A collection of such samples from the soil can disturb sample structure, so great care must be taken during collection to avoid this. Factors such as transportation and sample storage can also influence measurement results. The use of technologies like Thermal Response Test (TRT) require complex mechanical and electrical systems for convective heat transport in the subsurface and longer monitoring times, often three days. Finally, by using thermal response tests, often only one integral value is obtained for the entire coupled subsurface with the borehole heat exchanger. The common thermal conductivity measurement systems (thermal analyzers) can perform vertical thermal conductivity logs only with the aid of sample procurement, or by integration into a drilling system. However, thermal conductivity measurements using direct push with this type of probes are not possible, due to physical and mechanical limitations. Applying vertical forces using direct push technology, in order to penetrate the shallow subsurface, can damage the probe and the sensors systems. The aim of this study is to develop a new, robust thermal conductivity measurement probe, for direct push based approaches, called Thermal Conductivity Profiler (TCP), that operates based on the principles of a hollow cylindrical geometry heat source. To determinate thermal conductivity in situ, the transient temperature at the middle of the probe and electrical power dissipation is measured. At the same time, this work presents laboratory results obtained when this novel hollow cylindrical probe system was tested on different materials for calibration. By using the hollow cylindrical probe, the thermal conductivity results have an error of less than 2.5% error for solid samples (Teflon, Agar jelly, and Nylatron). These findings are useful to achieve a proper thermal energy balance in the shallow subsurface by using direct push technology and TCP. By providing information of layers with high thermal conductivity, suitable for thermal storage capability, can be used determine borehole heat exchanger design and, therefore, determine geothermal heat pump architecture.

Measuring Subsurface Water Fluxes Using a Heat Pulse Sensor

NASA Astrophysics Data System (ADS)

Ochsner, T. E.; Wang, Q.; Horton, R.

2001-12-01

Subsurface water flux is an important parameter in studies of runoff, infiltration, groundwater recharge, and subsurface chemical transport. Heat pulse sensors have been proposed as promising tools for measuring subsurface water fluxes. Our heat pulse probe consists of three 4-cm stainless-steel needles embedded in a waterproof epoxy body. The needles contain resistance heaters and thermocouples. The probes are connected to an external datalogger and power supply and then installed in soil. To measure the water flux, a 15-s heat pulse is generated at the middle needle using the power supply and the resistance heater, and the temperature increases at the needles 6-mm upstream and downstream from the heater are recorded using the thermocouples and datalogger. To date, heat pulse methods have required cumbersome mathematical analysis to calculate soil water flux from this measured data. We present a new mathematical analysis showing that a simple relationship exists between water flux and the ratio of the temperature increase downstream from the line heat source to the temperature increase upstream from the line heat source. The simplicity of this relationship makes heat pulse sensors a more attractive option for measuring subsurface water fluxes.

A multi-scale experimental and simulation approach for fractured subsurface systems

NASA Astrophysics Data System (ADS)

Viswanathan, H. S.; Carey, J. W.; Frash, L.; Karra, S.; Hyman, J.; Kang, Q.; Rougier, E.; Srinivasan, G.

2017-12-01

Fractured systems play an important role in numerous subsurface applications including hydraulic fracturing, carbon sequestration, geothermal energy and underground nuclear test detection. Fractures that range in scale from microns to meters and their structure control the behavior of these systems which provide over 85% of our energy and 50% of US drinking water. Determining the key mechanisms in subsurface fractured systems has been impeded due to the lack of sophisticated experimental methods to measure fracture aperture and connectivity, multiphase permeability, and chemical exchange capacities at the high temperature, pressure, and stresses present in the subsurface. In this study, we developed and use microfluidic and triaxial core flood experiments required to reveal the fundamental dynamics of fracture-fluid interactions. In addition we have developed high fidelity fracture propagation and discrete fracture network flow models to simulate these fractured systems. We also have developed reduced order models of these fracture simulators in order to conduct uncertainty quantification for these systems. We demonstrate an integrated experimental/modeling approach that allows for a comprehensive characterization of fractured systems and develop models that can be used to optimize the reservoir operating conditions over a range of subsurface conditions.

Microbial community assembly and evolution in subseafloor sediment.

PubMed

Starnawski, Piotr; Bataillon, Thomas; Ettema, Thijs J G; Jochum, Lara M; Schreiber, Lars; Chen, Xihan; Lever, Mark A; Polz, Martin F; Jørgensen, Bo B; Schramm, Andreas; Kjeldsen, Kasper U

2017-03-14

Bacterial and archaeal communities inhabiting the subsurface seabed live under strong energy limitation and have growth rates that are orders of magnitude slower than laboratory-grown cultures. It is not understood how subsurface microbial communities are assembled and whether populations undergo adaptive evolution or accumulate mutations as a result of impaired DNA repair under such energy-limited conditions. Here we use amplicon sequencing to explore changes of microbial communities during burial and isolation from the surface to the >5,000-y-old subsurface of marine sediment and identify a small core set of mostly uncultured bacteria and archaea that is present throughout the sediment column. These persisting populations constitute a small fraction of the entire community at the surface but become predominant in the subsurface. We followed patterns of genome diversity with depth in four dominant lineages of the persisting populations by mapping metagenomic sequence reads onto single-cell genomes. Nucleotide sequence diversity was uniformly low and did not change with age and depth of the sediment. Likewise, there was no detectable change in mutation rates and efficacy of selection. Our results indicate that subsurface microbial communities predominantly assemble by selective survival of taxa able to persist under extreme energy limitation.

Results from Field Testing the RIMFAX GPR on Svalbard.

NASA Astrophysics Data System (ADS)

Hamran, S. E.; Amundsen, H. E. F.; Berger, T.; Carter, L. M.; Dypvik, H.; Ghent, R. R.; Kohler, J.; Mellon, M. T.; Nunes, D. C.; Paige, D. A.; Plettemeier, D.; Russell, P.

2017-12-01

The Radar Imager for Mars' Subsurface Experiment - RIMFAX is a Ground Penetrating Radar being developed for NASÁs MARS 2020 rover mission. The principal goals of the RIMFAX investigation are to image subsurface structures, provide context for sample sites, derive information regarding subsurface composition, and search for ice or brines. In meeting these goals, RIMFAX will provide a view of the stratigraphic section and a window into the geological and environmental history of Mars. To verify the design an Engineering Model (EM) of the radar was tested in the field in the spring 2017. Different sounding modes on the EM were tested in different types of subsurface geology on Svalbard. Deep soundings were performed on polythermal glaciers down to a couple of hundred meters. Shallow soundings were used to map a ground water table in the firn area of a glacier. A combination of deep and shallow soundings was used to image buried ice under a sedimentary layer of a couple of meters. Subsurface sedimentary layers were imaged down to more than 20 meters in sand stone permafrost. This presentation will give an overview of the RIMFAX investigation, describe the development of the radar system, and show results from field tests of the radar.

Concentrations of inorganic arsenic in groundwater, agricultural soils and subsurface sediments from the middle Gangetic plain of Bihar, India.

PubMed

Kumar, Manoj; Ramanathan, A L; Rahman, Mohammad Mahmudur; Naidu, Ravi

2016-12-15

Concentrations of inorganic forms [arsenite, As(III) and arsenate, As(V) of arsenic (As) present in groundwater, agricultural soils and subsurface sediments located in the middle Gangetic plain of Bihar, India were determined. Approximately 73% of the groundwater samples (n=19) show As(III) as the dominant species while 27% reveals As(V) was the dominant species. The concentration of As(III) in agricultural soil samples varies from not detectable to 40μg/kg and As(V) was observed as the major species (ranging from 1050 to 6835μg/kg) while the total As concentration varied from 3528 to 14,690μg/kg. Total extracted concentration of As was higher in the subsurface sediments (range 9119-20,056μg/kg in Methrapur and 4788-19,681μg/kg in Harail Chapar) than the agricultural soil, indicating the subsurface sediment as a source of As. Results of X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) revealed the presence of hematite and goethite throughout the vertical section below while magnetite was observed only in the upper oxidized layer at Methrapur and Harail Chapar. Alteration of Fe-oxides and presence of fibrous goethite indicating presence of diagenetic sediment. Siderite plays a crucial role as sinks to the As in subsurface sediments. The study also concluded that decomposition of organic matter present in dark and grey sections promote the redox conditions and trigger mobilization of As into groundwater. Copyright © 2016 Elsevier B.V. All rights reserved.

Implications of Polishing Techniques in Quantitative X-Ray Microanalysis

PubMed Central

Rémond, Guy; Nockolds, Clive; Phillips, Matthew; Roques-Carmes, Claude

2002-01-01

Specimen preparation using abrasives results in surface and subsurface mechanical (stresses, strains), geometrical (roughness), chemical (contaminants, reaction products) and physical modifications (structure, texture, lattice defects). The mechanisms involved in polishing with abrasives are presented to illustrate the effects of surface topography, surface and subsurface composition and induced lattice defects on the accuracy of quantitative x-ray microanalysis of mineral materials with the electron probe microanalyzer (EPMA). PMID:27446758

Differential depth distribution of microbial function and putative symbionts through sediment-hosted aquifers in the deep terrestrial subsurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Probst, Alexander J.; Ladd, Bethany; Jarett, Jessica K.

An enormous diversity of previously unknown bacteria and archaea has been discovered recently, yet their functional capacities and distributions in the terrestrial subsurface remain uncertain. Here, we continually sampled a CO 2-driven geyser (Colorado Plateau, Utah, USA) over its 5-day eruption cycle to test the hypothesis that stratified, sandstone-hosted aquifers sampled over three phases of the eruption cycle have microbial communities that differ both in membership and function. Genome-resolved metagenomics, single-cell genomics and geochemical analyses confirmed this hypothesis and linked microorganisms to groundwater compositions from different depths. Autotrophic Candidatus “Altiarchaeum sp.” and phylogenetically deep-branching nanoarchaea dominate the deepest groundwater. Amore » nanoarchaeon with limited metabolic capacity is inferred to be a potential symbiont of the Ca. “Altiarchaeum”. Candidate Phyla Radiation bacteria are also present in the deepest groundwater and they are relatively abundant in water from intermediate depths. During the recovery phase of the geyser, microaerophilic Fe- and S-oxidizers have high in situ genome replication rates. Autotrophic Sulfurimonas sustained by aerobic sulfide oxidation and with the capacity for N 2 fixation dominate the shallow aquifer. Overall, 104 different phylum-level lineages are present in water from these subsurface environments, with uncultivated archaea and bacteria partitioned to the deeper subsurface.« less

Active Region Formation and Subsurface Structure

NASA Astrophysics Data System (ADS)

Stein, F.; Nordlund, Robert A.

2016-10-01

We present results from emerging magnetic flux simulations showing how several different active regions form and their very different subsurface structures. The simulations assumed an infinite sheet of uniform, untwisted, horizontal field advected into the computational domain by inflows at a depth of 20 Mm. Results from two different horizontal field strengths, 1 and 5 kG, will be presented. Convective up and down flows buckle the horizontal field into Omega and U loops. Upflows and magnetic buoyancy carry the field toward the surface, while fast downflows pin down the field. Small (granular) convective motions, near the surface, shred the emerging field into fine filaments that emerge as the observed "pepper and salt" pattern. The large (supergranular) motions, at depth, keep the overall loop structure intact, so that as the overall omega-loop emerges through the surface the opposite polarity fields counter-stream into large unipolar flux concentrations producing first pores which then coalesce into spots. These tend to be located over the supergranular downflow lanes near the bottom of the domain. The pores and spots exhibit a great variety of subsurface field structures - from monolithic but twisted bundles to intertwined separate spaghetti sturctures. We will show movies of the surface evolution of the field and emergent continuum intensity and of the subsurface evolution of the magnetic field lines.

Differential depth distribution of microbial function and putative symbionts through sediment-hosted aquifers in the deep terrestrial subsurface

DOE PAGES

Probst, Alexander J.; Ladd, Bethany; Jarett, Jessica K.; ...

2018-01-29

An enormous diversity of previously unknown bacteria and archaea has been discovered recently, yet their functional capacities and distributions in the terrestrial subsurface remain uncertain. Here, we continually sampled a CO 2-driven geyser (Colorado Plateau, Utah, USA) over its 5-day eruption cycle to test the hypothesis that stratified, sandstone-hosted aquifers sampled over three phases of the eruption cycle have microbial communities that differ both in membership and function. Genome-resolved metagenomics, single-cell genomics and geochemical analyses confirmed this hypothesis and linked microorganisms to groundwater compositions from different depths. Autotrophic Candidatus “Altiarchaeum sp.” and phylogenetically deep-branching nanoarchaea dominate the deepest groundwater. Amore » nanoarchaeon with limited metabolic capacity is inferred to be a potential symbiont of the Ca. “Altiarchaeum”. Candidate Phyla Radiation bacteria are also present in the deepest groundwater and they are relatively abundant in water from intermediate depths. During the recovery phase of the geyser, microaerophilic Fe- and S-oxidizers have high in situ genome replication rates. Autotrophic Sulfurimonas sustained by aerobic sulfide oxidation and with the capacity for N 2 fixation dominate the shallow aquifer. Overall, 104 different phylum-level lineages are present in water from these subsurface environments, with uncultivated archaea and bacteria partitioned to the deeper subsurface.« less

Subsurface flow and vegetation patterns in tidal environments

NASA Astrophysics Data System (ADS)

Ursino, Nadia; Silvestri, Sonia; Marani, Marco

2004-05-01

Tidal environments are characterized by a complex interplay of hydrological, geomorphic, and biological processes, and their understanding and modeling thus require the explicit description of both their biotic and abiotic components. In particular, the presence and spatial distribution of salt marsh vegetation (a key factor in the stabilization of the surface soil) have been suggested to be related to topographic factors and to soil moisture patterns, but a general, process-based comprehension of this relationship has not yet been achieved. The present paper describes a finite element model of saturated-unsaturated subsurface flow in a schematic salt marsh, driven by tidal fluctuations and evapotranspiration. The conditions leading to the establishment of preferentially aerated subsurface zones are studied, and inferences regarding the development and spatial distribution of salt marsh vegetation are drawn, with important implications for the overall ecogeomorphological dynamics of tidal environments. Our results show that subsurface water flow in the marsh induces complex water table dynamics, even when the tidal forcing has a simple sinusoidal form. The definition of a space-dependent aeration time is then proposed to characterize root aeration. The model shows that salt marsh subsurface flow depends on the distance from the nearest creek or channel and that the subsurface water movement near tidal creeks is both vertical and horizontal, while farther from creeks, it is primarily vertical. Moreover, the study shows that if the soil saturated conductivity is relatively low (10-6 m s-1, values quite common in salt marsh areas), a persistently unsaturated zone is present below the soil surface even after the tide has flooded the marsh; this provides evidence of the presence of an aerated layer allowing a prolonged presence of oxygen for aerobic root respiration. The results further show that plant transpiration increases the extent and persistence of the aerated layer, thereby introducing a strong positive feedback: Pioneer plants on marsh edges have the effect of increasing soil oxygen availability, thus creating the conditions for the further development of other plant communities.

Cometary activity and nucleus modelling: a new approach

NASA Astrophysics Data System (ADS)

Möhlmann, D.

1996-06-01

The phenomena of comet splittings with an average frequency of about one splitting per 100 years and comet (Chen and Jewitt, Icarus108, 265-271, 1994), and the restriction of cometary activity to well-defined small areas at the almost passive and mantle covered surface (Keller et al., ESA SP-250, Vol. II, pp. 363-364, 1986) are at present driving challenges to models of structure and evolution of comet nuclei. Extending the presently discussed models by incorporating lateral subsurface transport of sublimed volatiles, there appears the possibility that the places of sublimation are different from those of activity (the so-called active areas). Then, there is no necessity to distinguish between different surface properties at active and passive areas, assuming, e.g. an uncovered icy surface at active areas. Active areas are simply the very local "source sites" where the accumulated subsurface flows from distant regions reach the surface. The pressure driven subsurface flows of volatiles may not only leave the comet at its surface, they may penetrate via cracks, etc. also deeply into the nucleus. There they can cause a further growth of cracks and also new cracks. This can be a cause for the observed regular splittings. Furthermore, actual models (Kührt and Keller, Icarus109, 121-132, 1994; Skorov and Rickman, Planet. Space Sci.43, 1587-1594, 1995) of the gas transport through porous comet surface crusts can be interpreted as to give first indications for thermodynamical parameters in heat conducting and porous cometary crusts which are appropriate for 1 AU conditions to permit the temporary existence of a layer with fluid subsurface water within these crusts. This exciting result of the possible temporary existence of subsurface warm water in comets which approach the Sun within about 1 AU makes a cometary subsurface chemistry much more efficient than expected hitherto.

Shallow characterization of the subsurface for the 2018 Mission to Mars

NASA Astrophysics Data System (ADS)

Ciarletti, V.; plettemeier, D.; Vieau, A. J.; Hassen-Khodja, R.; Lustrement, B.; Cais, P.; Clifford, S.

2012-04-01

The highest priority scientific objectives of the revised 2018 mission to Mars are (1) to search for evidence of past or present life, (2) to identify the samples that are most likely to preserve potential evidence of life and the nature of the early Martian environment that might have given rise to it and (3) to cache them for later retrieval back to Earth for more detailed analyses than can be performed by the rover's onboard analytical laboratory. WISDOM is a ground penetrating radar that has been designed to investigate the near subsurface of Mars down to a depth of ~2-3 m, with a vertical resolution of several centimeters - commensurate with the sampling capabilities of the ExoMars onboard drill. The ability of WISDOM to investigate the geology of the landing site in 3-dimensions will permit direct correlations between subsurface layers and horizons with those exposed in nearby outcrops and the interior of impact craters. By combining periodic soundings conducted during a Rover traverse with targeted, high density grid-type soundings of areas of potential scientific interest, it will be possible to construct a 3-dimensional map of the local radar stratigraphy. Of all of the Pasteur Payload instruments, only WISDOM has the ability to investigate and characterize the nature of the subsurface remotely. Moreover, the geoelectrical properties of H2O make WISDOM a powerful tool to understand the local distribution and state of subsurface H2O, including the potential presence of segregated ground ice and the persistent or transient occurrence of liquid water/brine. A WISDOM prototype, representative of the final flight model is now being tested. A series of calibrations and verifications have been initiated. The real performance of the instrument is currently assessed for various test environments. Results about the resolution and sensitivity achieved are presented as well as 3D representations of detected subsurface structures. Preliminary estimates of permittivity values are also shown.

Integrated Coupling of Surface and Subsurface Flow with HYDRUS-2D

NASA Astrophysics Data System (ADS)

Hartmann, Anne; Šimůnek, Jirka; Wöhling, Thomas; Schütze, Niels

2016-04-01

Describing interactions between surface and subsurface flow processes is important to adequately define water flow in natural systems. Since overland flow generation is highly influenced by rainfall and infiltration, both highly spatially heterogeneous processes, overland flow is unsteady and varies spatially. The prediction of overland flow needs to include an appropriate description of the interactions between the surface and subsurface flow. Coupling surface and subsurface water flow is a challenging task. Different approaches have been developed during the last few years, each having its own advantages and disadvantages. A new approach by Weill et al. (2009) to couple overland flow and subsurface flow based on a generalized Richards equation was implemented into the well-known subsurface flow model HYDRUS-2D (Šimůnek et al., 2011). This approach utilizes the one-dimensional diffusion wave equation to model overland flow. The diffusion wave model is integrated in HYDRUS-2D by replacing the terms of the Richards equation in a pre-defined runoff layer by terms defining the diffusion wave equation. Using this approach, pressure and flux continuity along the interface between both flow domains is provided. This direct coupling approach provides a strong coupling of both systems based on the definition of a single global system matrix to numerically solve the coupled flow problem. The advantage of the direct coupling approach, compared to the loosely coupled approach, is supposed to be a higher robustness, when many convergence problems can be avoided (Takizawa et al., 2014). The HYDRUS-2D implementation was verified using a) different test cases, including a direct comparison with the results of Weill et al. (2009), b) an analytical solution of the kinematic wave equation, and c) the results of a benchmark test of Maxwell et al. (2014), that included several known coupled surface subsurface flow models. Additionally, a sensitivity analysis evaluating the effects of various model parameters on simulated overland flow (while considering or neglecting the effects of subsurface flow) was carried out to verify the applicability of the model to different problems. The model produced reasonable results in describing the diffusion wave approximation and its interactions with subsurface flow processes. The model could handle coupled surface-subsurface processes for conditions involving runoff generated by infiltration excess, saturation excess, or run-on, as well as a combination of these runoff generating processes. Several standard features of the HYDRUS 2D model, such as root water uptake and evaporation from the soil surface, as well as evaporation from runoff layer, can still be considered by the new model. The code required relatively small time steps when overland flow was active, resulting in long simulation times, and sometimes produced poor mass balance. The model nevertheless showed potential to be a useful tool for addressing various issues related to irrigation research and to natural generation of overland flow at the hillslope scale. Maxwell, R., Putti, M., Meyerhoff, S., Delf, J., Ferguson, I., Ivanov, V., Kim, J., Kolditz, O., Kollet, S., Kumar, M., Lopez, S., Niu, J., Paniconi, C., Park, Y.-J., Phanikumar, M., Shen, C., Sudicky, E., and Sulis, M. (2014). Surface-subsurface model intercomparison: A first set of benchmark results to diagnose integrated hydrology and feedbacks. Water Resourc. Res., 50:1531-1549. Šimůnek, J., van Genuchten, M. T., and Šejna, M. (2011). The HYDRUS Software Package for Simulating Two- and Three-Dimensional Movement of Water, Heat, and Multiple Solutes in Variably-Saturated Media. Technical Manual, Version 2.0, PC Progress, Prague, Czech Republic. Takizawa, K., Bazilevs Y., Tezduyar, T. E., Long, C.C., Marsden, A. L. and Schjodt.K., Patient-Specific Cardiovascular Fluid Mechanics Analysis with the ST and ALE-VMS Method in Idelsohn, S. R. (2014). Numerical Simulations of Coupled Problems in Engineering. Springer. Weill, S., Mouche, E., and Patin, J. (2009). A generalized Richards equation for surface/subsurface flow modelling. Journal of Hydrology, 366:9-20.

Characterization of arsenite-oxidizing bacteria to decipher their role in arsenic bioremediation.

PubMed

Biswas, Rimi; Sarkar, Angana

2018-06-11

High arsenic groundwater contamination causes serious health risks in many developing countries, particularly in India and Bangladesh. The arsenic fluxes in aquifers are primarily controlled by bacterial populations through biogeochemical cycle. In this present study, two gram-positive rod-shaped bacteria were isolated from shallow aquifers of Bhojpur district in Bihar during the early winter season, able to withstand arsenite (As 3+ ) concentration upto 70 mM and 1000 mM of arsenate (As 5+ ) concentration. They showed high resistance to heavy metals up to 30 mM and utilized some complex sugars along with different carbon sources. Growth at wide range of temperature, pH and salinity were observed. Both these isolates showed high efficiency in converting As 3+ into less toxic concentrations of As 5+ respectively from arsenic enriched culture media. Along with superior arsenic transformation and arsenic resistance abilities, the isolates showed a wide variety of metabolic capacity in terms of utilizing a variety of carbon sources under aerobic conditions, respectively. This study reports the potential As 3+ -oxidizing bacteria that can play an important role in subsurface arsenic transformation that will aid in designing future bioremediation strategy for the arsenic affected areas.

Field demonstration of polymer-amended in situ chemical oxidation (PA-ISCO)

NASA Astrophysics Data System (ADS)

Silva, Jeff A. K.; Crimi, Michelle; Palaia, Thomas; Ko, Saebom; Davenport, Sean

2017-04-01

The methods and results of the first field-scale demonstration of polymer-amended in situ chemical oxidation (PA-ISCO) are presented. The demonstration took place at MCB CAMLEJ (Marine Corps Base, Camp Lejeune) Operable Unit (OU) 15, Site 88, in Camp Lejeune, North Carolina between October and December 2010. PA-ISCO was developed as an alternative treatment approach that utilizes viscosity-modified fluids to improve the in situ delivery and distribution (i.e. sweep-efficiency) of chemical oxidants within texturally heterogeneous contaminated aquifers. The enhanced viscosity of the fluid mitigates the effects of preferential flows, improving sweep-efficiency and enhancing the subsurface contact between the injected oxidant and the target contamination within the treatment zone. The PA-ISCO fluid formulation used in this demonstration included sodium permanganate as oxidant, xanthan gum biopolymer as a shear-thinning viscosifier, and sodium hexametaphosphate (SHMP) as an anti-coagulant. It was the goal of this demonstration to validate the utility of PA-ISCO within a heterogeneous aquifer. An approximate 100% improvement in sweep-efficiency was achieved for the PA-ISCO fluid, as compared to a permanganate-only injection within an adjacent control plot.

Fortuitous encounters between seagliders and adult female northern fur seals (Callorhinus ursinus) off the Washington (USA) coast: upper ocean variability and links to top predator behavior.

PubMed

Pelland, Noel A; Sterling, Jeremy T; Lea, Mary-Anne; Bond, Nicholas A; Ream, Rolf R; Lee, Craig M; Eriksen, Charles C

2014-01-01

Behavioral responses by top marine predators to oceanographic features such as eddies, river plumes, storms, and coastal topography suggest that biophysical interactions in these zones affect predators' prey, foraging behaviors, and potentially fitness. However, examining these pathways is challenged by the obstacles inherent in obtaining simultaneous observations of surface and subsurface environmental fields and predator behavior. In this study, migratory movements and, in some cases, diving behavior of 40 adult female northern fur seals (NFS; Callorhinus ursinus) were quantified across their range and compared to remotely-sensed environmental data in the Gulf of Alaska and California Current ecosystems, with a particular focus off the coast of Washington State (USA)--a known foraging ground for adult female NFS and where autonomous glider sampling allowed opportunistic comparison of seal behavior to subsurface biophysical measurements. The results show that in these ecosystems, adult female habitat utilization was concentrated near prominent coastal topographic, riverine, or inlet features and within 200 km of the continental shelf break. Seal dive depths, in most ecosystems, were moderated by surface light level (solar or lunar), mirroring known behaviors of diel vertically-migrating prey. However, seal dives differed in the California Current ecosystem due to a shift to more daytime diving concentrated at or below the surface mixed layer base. Seal movement models indicate behavioral responses to season, ecosystem, and surface wind speeds; individuals also responded to mesoscale eddies, jets, and the Columbia River plume. Foraging within small scale surface features is consistent with utilization of the inner coastal transition zone and habitats near coastal capes, which are known eddy and filament generation sites. These results contribute to our knowledge of NFS migratory patterns by demonstrating surface and subsurface behavioral responses to a spatially and temporally dynamic ocean environment, thus reflecting its influence on associated NFS prey species.

Fortuitous Encounters between Seagliders and Adult Female Northern Fur Seals (Callorhinus ursinus) off the Washington (USA) Coast: Upper Ocean Variability and Links to Top Predator Behavior

PubMed Central

Pelland, Noel A.; Sterling, Jeremy T.; Lea, Mary-Anne; Bond, Nicholas A.; Ream, Rolf R.; Lee, Craig M.; Eriksen, Charles C.

2014-01-01

Behavioral responses by top marine predators to oceanographic features such as eddies, river plumes, storms, and coastal topography suggest that biophysical interactions in these zones affect predators' prey, foraging behaviors, and potentially fitness. However, examining these pathways is challenged by the obstacles inherent in obtaining simultaneous observations of surface and subsurface environmental fields and predator behavior. In this study, migratory movements and, in some cases, diving behavior of 40 adult female northern fur seals (NFS; Callorhinus ursinus) were quantified across their range and compared to remotely-sensed environmental data in the Gulf of Alaska and California Current ecosystems, with a particular focus off the coast of Washington State (USA) – a known foraging ground for adult female NFS and where autonomous glider sampling allowed opportunistic comparison of seal behavior to subsurface biophysical measurements. The results show that in these ecosystems, adult female habitat utilization was concentrated near prominent coastal topographic, riverine, or inlet features and within 200 km of the continental shelf break. Seal dive depths, in most ecosystems, were moderated by surface light level (solar or lunar), mirroring known behaviors of diel vertically-migrating prey. However, seal dives differed in the California Current ecosystem due to a shift to more daytime diving concentrated at or below the surface mixed layer base. Seal movement models indicate behavioral responses to season, ecosystem, and surface wind speeds; individuals also responded to mesoscale eddies, jets, and the Columbia River plume. Foraging within small scale surface features is consistent with utilization of the inner coastal transition zone and habitats near coastal capes, which are known eddy and filament generation sites. These results contribute to our knowledge of NFS migratory patterns by demonstrating surface and subsurface behavioral responses to a spatially and temporally dynamic ocean environment, thus reflecting its influence on associated NFS prey species. PMID:25153524

Fe-oxide grain coatings support bacterial Fe-reducing metabolisms in 1.7−2.0 km-deep subsurface quartz arenite sandstone reservoirs of the Illinois Basin (USA)

PubMed Central

Dong, Yiran; Sanford, Robert A.; Locke, Randall A.; Cann, Isaac K.; Mackie, Roderick I.; Fouke, Bruce W.

2014-01-01

The Cambrian-age Mt. Simon Sandstone, deeply buried within the Illinois Basin of the midcontinent of North America, contains quartz sand grains ubiquitously encrusted with iron-oxide cements and dissolved ferrous iron in pore-water. Although microbial iron reduction has previously been documented in the deep terrestrial subsurface, the potential for diagenetic mineral cementation to drive microbial activity has not been well studied. In this study, two subsurface formation water samples were collected at 1.72 and 2.02 km, respectively, from the Mt. Simon Sandstone in Decatur, Illinois. Low-diversity microbial communities were detected from both horizons and were dominated by Halanaerobiales of Phylum Firmicutes. Iron-reducing enrichment cultures fed with ferric citrate were successfully established using the formation water. Phylogenetic classification identified the enriched species to be related to Vulcanibacillus from the 1.72 km depth sample, while Orenia dominated the communities at 2.02 km of burial depth. Species-specific quantitative analyses of the enriched organisms in the microbial communities suggest that they are indigenous to the Mt. Simon Sandstone. Optimal iron reduction by the 1.72 km enrichment culture occurred at a temperature of 40°C (range 20–60°C) and a salinity of 25 parts per thousand (range 25–75 ppt). This culture also mediated fermentation and nitrate reduction. In contrast, the 2.02 km enrichment culture exclusively utilized hydrogen and pyruvate as the electron donors for iron reduction, tolerated a wider range of salinities (25–200 ppt), and exhibited only minimal nitrate- and sulfate-reduction. In addition, the 2.02 km depth community actively reduces the more crystalline ferric iron minerals goethite and hematite. The results suggest evolutionary adaptation of the autochthonous microbial communities to the Mt. Simon Sandstone and carries potentially important implications for future utilization of this reservoir for CO2 injection. PMID:25324834

GIS based 3D visualization of subsurface and surface lineaments / faults and their geological significance, northern tamil nadu, India

NASA Astrophysics Data System (ADS)

Saravanavel, J.; Ramasamy, S. M.

2014-11-01

The study area falls in the southern part of the Indian Peninsular comprising hard crystalline rocks of Archaeozoic and Proterozoic Era. In the present study, the GIS based 3D visualizations of gravity, magnetic, resistivity and topographic datasets were made and therefrom the basement lineaments, shallow subsurface lineaments and surface lineaments/faults were interpreted. These lineaments were classified as category-1 i.e. exclusively surface lineaments, category-2 i.e. surface lineaments having connectivity with shallow subsurface lineaments and category-3 i.e. surface lineaments having connectivity with shallow subsurface lineaments and basement lineaments. These three classified lineaments were analyzed in conjunction with known mineral occurrences and historical seismicity of the study area in GIS environment. The study revealed that the category-3 NNE-SSW to NE-SW lineaments have greater control over the mineral occurrences and the N-S, NNE-SSW and NE-SW, faults/lineaments control the seismicities in the study area.

Theoretical analysis of optical properties of dielectric coatings dependence on substrate subsurface defects

NASA Astrophysics Data System (ADS)

Shen, Jian; Liu, Shouhua; Shen, Zicai; Shao, Jianda; Fan, Zhengxiu

2006-03-01

A model for refractive index of stratified dielectric substrate was put forward according to theories of inhomogeneous coatings. The substrate was divided into surface layer, subsurface layer and bulk layer along the normal direction of its surface. Both the surface layer (separated into N1 sublayers of uniform thickness) and subsurface layer (separated into N2 sublayers of uniform thickness), whose refractive indices have different statistical distributions, are equivalent to inhomogeneous coatings, respectively. And theoretical deduction was carried out by employing characteristic matrix method of optical coatings. An example of mathematical calculation for optical properties of dielectric coatings had been presented. The computing results indicate that substrate subsurface defects can bring about additional bulk scattering and change propagation characteristic in thin film and substrate. Therefore, reflectance, reflective phase shift and phase difference of an assembly of coatings and substrate deviate from ideal conditions. The model will provide some beneficial theory directions for improving optical properties of dielectric coatings via substrate surface modification.

[Characterizing composition and transformation of dissolved organic matter in subsurface wastewater infiltration system].

PubMed

Wang, Li-Jun; Liu, Yu-Zhong; Zhang, Lie-Yu; Xi, Bei-Dou; Xia, Xun-Feng; Liu, Ya-Ru

2013-08-01

In the present study, the soil column with radius of 30 cm and height of 200 cm was used to simulate a subsurface wastewater infiltration system. Under the hydraulic loading of 4 cm x d(-1), composition and transformation of dissolved organic matter (DOM) from different depths were analyzed in a subsurface wastewater infiltration system for treatment of septic tank effluent using three-dimensional excitation emission matrix fluorescence spectroscopy (3D-EEM) with regional integration analysis (FRI). The results indicate that: (1) from different depth, the composition of DOM was also different; influent with the depth of 0.5 m was mainly composed of protein-like substances, and that at other depths was mainly composed of humic- and fulvic-like substances. (2) DOM stability gradually increased and part of the nonbiodegradable organic matter can be removed during organic pollutants degradation process. (3) Not only the organic pollutants concentration was reduced effectively, but also the stability of the DOM improved in subsurface wastewater infiltration system.

Simulating pathways of subsurface oil in the Faroe-Shetland Channel using an ocean general circulation model.

PubMed

Main, C E; Yool, A; Holliday, N P; Popova, E E; Jones, D O B; Ruhl, H A

2017-01-15

Little is known about the fate of subsurface hydrocarbon plumes from deep-sea oil well blowouts and their effects on processes and communities. As deepwater drilling expands in the Faroe-Shetland Channel (FSC), oil well blowouts are a possibility, and the unusual ocean circulation of this region presents challenges to understanding possible subsurface oil pathways in the event of a spill. Here, an ocean general circulation model was used with a particle tracking algorithm to assess temporal variability of the oil-plume distribution from a deep-sea oil well blowout in the FSC. The drift of particles was first tracked for one year following release. Then, ambient model temperatures were used to simulate temperature-mediated biodegradation, truncating the trajectories of particles accordingly. Release depth of the modeled subsurface plumes affected both their direction of transport and distance travelled from their release location, and there was considerable interannual variability in transport. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Line-scan spatially offset Raman spectroscopy for inspecting subsurface food safety and quality

NASA Astrophysics Data System (ADS)

Qin, Jianwei; Chao, Kuanglin; Kim, Moon S.

2016-05-01

This paper presented a method for subsurface food inspection using a newly developed line-scan spatially offset Raman spectroscopy (SORS) technique. A 785 nm laser was used as a Raman excitation source. The line-shape SORS data was collected in a wavenumber range of 0-2815 cm-1 using a detection module consisting of an imaging spectrograph and a CCD camera. A layered sample, which was created by placing a plastic sheet cut from the original container on top of cane sugar, was used to test the capability for subsurface food inspection. A whole set of SORS data was acquired in an offset range of 0-36 mm (two sides of the laser) with a spatial interval of 0.07 mm. Raman spectrum from the cane sugar under the plastic sheet was resolved using self-modeling mixture analysis algorithms, demonstrating the potential of the technique for authenticating foods and ingredients through packaging. The line-scan SORS measurement technique provides a new method for subsurface inspection of food safety and quality.

The Mojave vadose zone: a subsurface biosphere analogue for Mars.

PubMed

Abbey, William; Salas, Everett; Bhartia, Rohit; Beegle, Luther W

2013-07-01

If life ever evolved on the surface of Mars, it is unlikely that it would still survive there today, but as Mars evolved from a wet planet to an arid one, the subsurface environment may have presented a refuge from increasingly hostile surface conditions. Since the last glacial maximum, the Mojave Desert has experienced a similar shift from a wet to a dry environment, giving us the opportunity to study here on Earth how subsurface ecosystems in an arid environment adapt to increasingly barren surface conditions. In this paper, we advocate studying the vadose zone ecosystem of the Mojave Desert as an analogue for possible subsurface biospheres on Mars. We also describe several examples of Mars-like terrain found in the Mojave region and discuss ecological insights that might be gained by a thorough examination of the vadose zone in these specific terrains. Examples described include distributary fans (deltas, alluvial fans, etc.), paleosols overlain by basaltic lava flows, and evaporite deposits.

Let's Go Off the Grid: Subsurface Flow Modeling With Analytic Elements

NASA Astrophysics Data System (ADS)

Bakker, M.

2017-12-01

Subsurface flow modeling with analytic elements has the major advantage that no grid or time stepping are needed. Analytic element formulations exist for steady state and transient flow in layered aquifers and unsaturated flow in the vadose zone. Analytic element models are vector-based and consist of points, lines and curves that represent specific features in the subsurface. Recent advances allow for the simulation of partially penetrating wells and multi-aquifer wells, including skin effect and wellbore storage, horizontal wells of poly-line shape including skin effect, sharp changes in subsurface properties, and surface water features with leaky beds. Input files for analytic element models are simple, short and readable, and can easily be generated from, for example, GIS databases. Future plans include the incorporation of analytic element in parts of grid-based models where additional detail is needed. This presentation will give an overview of advanced flow features that can be modeled, many of which are implemented in free and open-source software.

Habitability of the Shallow Subsurface on Mars: Clues from the Meteorites

NASA Technical Reports Server (NTRS)

McKay, David S.; Wentworth, Susan J.; Thomas-Keprta, Kathie L.; Clemett, Simon; Gibson, Everett K.

2004-01-01

The properties that define habitability are commonly understood to include the following: Presence of water. Temperature range allowing some or all of the water to be liquid. A suitable physical volume or space permitting metabolism and growth. Presence of organic compounds or the building blocks to make them. Presence of an energy source suitable for utilization by living organisms. Interpretations of Mars Viking, Surveyor, and Odyssey orbital images have built a strong case that Mars had surface water during its past geological history. Neutron spectrometer data from Mars Odyssey show that poleward of about 60 degrees North and 60 degrees south, significant hydrogen, likely as ice or permafrost, is present in at least the upper meter or so of the martian regolith and crust and that similar high hydrogen areas exist, even near the equator. Here we present a summary of independent data from the Mars meteorites showing that liquid water was present for at least some of the time in the upper few meters or tens of meters as early as 3.9 billion years (Ga), and was present at intervals and at various locations throughout most of Mars history.

North Pacific deglacial hypoxic events linked to abrupt ocean warming

USGS Publications Warehouse

Praetorius, Summer K; Mix, Alan C.; Davies, Maureen H.; Wolhowe, Matthew D; Addison, Jason A.; Prahl, Frederick G

2015-01-01

Marine sediments from the North Pacific document two episodes of expansion and strengthening of the subsurface oxygen minimum zone (OMZ) accompanied by seafloor hypoxia during the last deglacial transition1, 2, 3, 4. The mechanisms driving this hypoxia remain under debate1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11. We present a new high-resolution alkenone palaeotemperature reconstruction from the Gulf of Alaska that reveals two abrupt warming events of 4–5 degrees Celsius at the onset of the Bølling and Holocene intervals that coincide with sudden shifts to hypoxia at intermediate depths. The presence of diatomaceous laminations and hypoxia-tolerant benthic foraminiferal species, peaks in redox-sensitive trace metals12, 13, and enhanced 15N/14N ratio of organic matter13, collectively suggest association with high export production. A decrease in 18O/16O values of benthic foraminifera accompanying the most severe deoxygenation event indicates subsurface warming of up to about 2 degrees Celsius. We infer that abrupt warming triggered expansion of the North Pacific OMZ through reduced oxygen solubility and increased marine productivity via physiological effects; following initiation of hypoxia, remobilization of iron from hypoxic sediments could have provided a positive feedback on ocean deoxygenation through increased nutrient utilization and carbon export. Such a biogeochemical amplification process implies high sensitivity of OMZ expansion to warming.

MURMoT. Design and Application of Microbial Uranium Reduction Monitoring Tools

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loeffler, Frank E.

2014-12-31

Uranium (U) contamination in the subsurface is a major remediation challenge at many DOE sites. Traditional site remedies present enormous costs to DOE; hence, enhanced bioremediation technologies (i.e., biostimulation and bioaugmentation) combined with monitoring efforts are being considered as cost-effective corrective actions to address subsurface contamination. This research effort improved understanding of the microbial U reduction process and developed new tools for monitoring microbial activities. Application of these tools will promote science-based site management decisions that achieve contaminant detoxification, plume control, and long-term stewardship in the most efficient manner. The overarching hypothesis was that the design, validation and application ofmore » a suite of new molecular and biogeochemical tools advance process understanding, and improve environmental monitoring regimes to assess and predict in situ U immobilization. Accomplishments: This project (i) advanced nucleic acid-based approaches to elucidate the presence, abundance, dynamics, spatial distribution, and activity of metal- and radionuclide-detoxifying bacteria; (ii) developed proteomics workflows for detection of metal reduction biomarker proteins in laboratory cultures and contaminated site groundwater; (iii) developed and demonstrated the utility of U isotopic fractionation using high precision mass spectrometry to quantify U(VI) reduction for a range of reduction mechanisms and environmental conditions; and (iv) validated the new tools using field samples from U-contaminated IFRC sites, and demonstrated their prognostic and diagnostic capabilities in guiding decision making for environmental remediation and long-term site stewardship.« less

Lateral, vertical, and longitudinal connectivity of runoff source areas drive stream hydro-biogeochemical signals across a low relief drainage network

NASA Astrophysics Data System (ADS)

Zimmer, M. A.; McGlynn, B. L.

2017-12-01

Our understanding of the balance between longitudinal, lateral, and vertical expansion and contraction of reactive flowpaths and source areas in headwater catchments is limited. To address this, we utilized an ephemeral-to-perennial stream network in the Piedmont region of North Carolina, USA to gain new understanding about critical zone mechanisms that drive runoff generation and biogeochemical signals in both groundwater and stream water. Here, we used chemical and hydrometric data collected from zero through second order catchments to characterize spatial and temporal runoff and overland, shallow soil, and deep subsurface flow across characteristic landscape positions. Our results showed that the active stream network was driven by two superimposed runoff generation regimes that produced distinct hydro-biogeochemical signals at the catchment outlet. The baseflow runoff generation regime expanded and contracted the stream network seasonally through the rise and fall of the seasonal water table. Superimposed on this, event-activated source area contributions were driven by surficial and shallow subsurface flowpaths. The subsurface critical zone stratigraphy in this landscape coupled with the precipitation regime activated these shallow flowpaths frequently. This drove an increase in dissolved organic carbon (DOC) concentrations with increases in runoff across catchment scales. DOC-runoff relationship variability and spread was driven by the balance between runoff regimes as well as a seasonal depletion of DOC from shallow subsurface flowpath activation and annual replenishment from litterfall. From this, we suggest that the hydro-biogeochemical signals at larger catchment outlets can be driven by a balance of longitudinal, lateral, and vertical source area contributions, critical zone structure, and complex hydrological processes.

Cave speleothems as repositories of microbial biosignatures

NASA Astrophysics Data System (ADS)

Miller, Ana Z.; Jurado, Valme; Pereira, Manuel F. C.; Fernández, Octavio; Calaforra, José M.; Dionísio, Amélia; Saiz-Jimenez, Cesareo

2015-04-01

The need to better understand the biodiversity, origins of life on Earth and on other planets, and the wide applications of the microbe-mineral interactions have led to a rapid expansion of interest in subsurface environments. Recently reported results indicated signs of an early wet Mars and rather recent volcanic activity which suggest that Mars's subsurface can house organic molecules or traces of microbial life, making the search for microbial life on Earth's subsurface even more compelling. Caves on Earth are windows into the subsurface that harbor a wide variety of mineral-utilizing microorganisms, which may contribute to the formation of biominerals and unusual microstructures recognized as biosignatures. These environments contain a wide variety of redox interfaces and stable physicochemical conditions, which enhance secondary mineral precipitation and microbial growth under limited organic nutrient inputs. Enigmatic microorganisms and unusual mineral features have been found associated with secondary mineral deposits or speleothems in limestone caves and lava tubes. In this study, Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray spectroscopy (EDS) analyses were conducted on cave speleothem samples to assess microbe-mineral interactions, evaluate biogenicity, as well as to describe unusual mineral formations and microbial features. Microbial mats, extracellular polymeric substances, tubular empty sheaths, mineralized cells, filamentous fabrics, as well as "cell-sized" etch pits or microborings produced by bacterial cells were observed on minerals. These features evidence microbe-mineral interactions and may represent mineralogical signatures of life. We can thus consider that caves on Earth are plausible repositories of terrestrial biosignatures where we can look for microbial signatures. Acknowledgments: AZM acknowledges the support from the Marie Curie Intra-European Fellowship within the 7th European Community Framework Programme (PIEF-GA-2012-328689- DECAVE). The authors acknowledge the Spanish Ministry of Economy and Competitiveness (project CGL2013-41674-P) for financial support.

High-Resolution Seismic Reflection Profiling Across the Black Hills Fault, Clark County, Nevada: Preliminary Results

NASA Astrophysics Data System (ADS)

Zaragoza, S. A.; Snelson, C. M.; Jernsletten, J. A.; Saldana, S. C.; Hirsch, A.; McEwan, D.

2005-12-01

The Black Hills fault (BHF) is located in the central Basin and Range Province of western North America, a region that has undergone significant Cenozoic extension. The BHF is an east-dipping normal fault that forms the northwestern structural boundary of the Eldorado basin and lies ~20 km southeast of Las Vegas, Nevada. A recent trench study indicated that the fault offsets Holocene strata, and is capable of producing Mw 6.4-6.8 earthquakes. These estimates indicate a subsurface rupture length at least 10 km greater than the length of the scarp. This poses a significant hazard to structures such as the nearby Hoover Dam Bypass Bridge, which is being built to withstand a Mw 6.2-7.0 earthquake on local faults. If the BHF does continue in the subsurface, this structure, as well as nearby communities (Las Vegas, Boulder City, and Henderson), may not be as safe as previously expected. Previous attempts to image the fault with shallow seismics (hammer source) were inconclusive. However, gravity studies imply that the fault continues south of the scarp. Therefore, a new experiment utilizing high-resolution seismic reflection was performed to image subsurface geologic structures south of the scarp. At each shot point, a stack of four 30-160 Hz vibroseis sweeps of 15 s duration was recorded on a 60-channel system with 40 Hz geophones. This produced two 300 m reflection profiles, with a maximum depth of 500-600 m. A preliminary look at these data indicates the existence of two faults, potentially confirming that the BHF continues in the subsurface south of the scarp.

Prediction of future subsurface temperatures in Korea

NASA Astrophysics Data System (ADS)

Lee, Y.; Kim, S. K.; Jeong, J.; SHIN, E.

2017-12-01

The importance of climate change has been increasingly recognized because it has had the huge amount of impact on social, economic, and environmental aspect. For the reason, paleoclimate change has been studied intensively using different geological tools including borehole temperatures and future surface air temperatures (SATs) have been predicted for the local areas and the globe. Future subsurface temperatures can have also enormous impact on various areas and be predicted by an analytical method or a numerical simulation using measured and predicted SATs, and thermal diffusivity data of rocks. SATs have been measured at 73 meteorological observatories since 1907 in Korea and predicted at same locations up to the year of 2100. Measured SATs at the Seoul meteorological observatory increased by about 3.0 K from the year of 1907 to the present. Predicted SATs have 4 different scenarios depending on mainly CO2 concentration and national action plan on climate change in the future. The hottest scenario shows that SATs in Korea will increase by about 5.0 K from the present to the year of 2100. In addition, thermal diffusivity values have been measured on 2,903 rock samples collected from entire Korea. Data pretreatment based on autocorrelation analysis was conducted to control high frequency noise in thermal diffusivity data. Finally, future subsurface temperatures in Korea were predicted up to the year of 2100 by a FEM simulation code (COMSOL Multiphysics) using measured and predicted SATs, and thermal diffusivity data in Korea. At Seoul, the results of predictions show that subsurface temperatures will increase by about 5.4 K, 3.0 K, 1.5 K, and 0.2 K from the present to 2050 and then by about 7.9 K, 4.8 K, 2.5 K, and 0.5 K to 2100 at the depths of 10 m, 50 m, 100 m, and 200 m, respectively. We are now proceeding numerical simulations for subsurface temperature predictions for 73 locations in Korea.

Astrobiology Exploration Strategies for the Mars Polar Regions Using Balloon Platforms

NASA Technical Reports Server (NTRS)

Mahaffy, P. R.; Atreya, S. A.; Fairbrother, D. A.; Farrell, W. M.; Gorevan, S.; Jones, J.; Mitrofanov, I.; Scott, J.

2003-01-01

Montgolfiere balloons can provide a unique near-surface platform for an extended traverse over the polar regions of Mars. During the polar summer, such solar powered balloons would remain in the constant sun of the polar summer and could remain airborne for many weeks or even months as the atmospheric circulation would drive the balloons around the polar region many times before the balloon would cross the terminator. Such a platform for scientific measurements could provide in situ sampling of the atmosphere for trace disequilibrium species that might be indicators of present geological or biological activity in this region. It could furthermore provide high resolution imaging, deep electromagnetic (EM) sounding for subsurface stratigraphy and liquid water, and high spatial resolution neutron measurements of subsurface ice. Technologies for robust balloon deployment on entry and controlled encounters with the surface and near subsurface for sample acquisition in otherwise inaccessible regions are presently being studied and developed with support from NASA.

Astrobiology Exploration Strategies for the Mars Polar Regions Using Balloon Platforms

NASA Technical Reports Server (NTRS)

Mahaffy, P. R.; Atreya, S. A.; Fairbrother, D. A.; Farrell, W. M.; Gorevan, S.; Jones, J.; Mitrofanov, I.; Scott, J.

2003-01-01

Montgolfiere balloons can provide a unique near-surface platform for an extended traverse over the polar regions of Mars. During the polar summer, such solar powered balloons would remain in the constant sun of the polar summer and could remain airborne for many weeks or even months as the atmospheric circulation would drive the balloons around the polar region many times before the balloon would cross the terminator. Such a platform for scientific measurements could provide in situ sampling of the atmosphere for trace disequilibrium species that might be indicators of present geological or biological activity in this regon. It could furthermore provide high resolution imaging, deep electromagnetic (EM) sounding for subsurface stratigraphy and liquid water, and high spatial resolution neutron measurements of subsurface ice. Technologies for robust balloon deployment on entry and controlled encounters with the surface and near subsurface for sample acquisition in otherwise inaccessible regions are presently being studied and developed with support from NASA.

Explosive hazard detection using MIMO forward-looking ground penetrating radar

NASA Astrophysics Data System (ADS)

Shaw, Darren; Ho, K. C.; Stone, Kevin; Keller, James M.; Popescu, Mihail; Anderson, Derek T.; Luke, Robert H.; Burns, Brian

2015-05-01

This paper proposes a machine learning algorithm for subsurface object detection on multiple-input-multiple-output (MIMO) forward-looking ground-penetrating radar (FLGPR). By detecting hazards using FLGPR, standoff distances of up to tens of meters can be acquired, but this is at the degradation of performance due to high false alarm rates. The proposed system utilizes an anomaly detection prescreener to identify potential object locations. Alarm locations have multiple one-dimensional (ML) spectral features, two-dimensional (2D) spectral features, and log-Gabor statistic features extracted. The ability of these features to reduce the number of false alarms and increase the probability of detection is evaluated for both co-polarizations present in the Akela MIMO array. Classification is performed by a Support Vector Machine (SVM) with lane-based cross-validation for training and testing. Class imbalance and optimized SVM kernel parameters are considered during classifier training.

Searching for organics on the dwarf planet Ceres

NASA Astrophysics Data System (ADS)

Nayak, Michael

The Herschel Space Observatory recently detected the presence of water vapor in observations of Ceres, bringing it into the crosshairs of the search for the building blocks of life in the solar system. I present a mission concept designed in collaboration with the NASA Ames Research Center for a two-probe mission to the dwarf planet Ceres, utilizing a pair of small low-cost spacecraft. The primary spacecraft will carry both a mass and an infrared spectrometer to characterize the detected vapor. Shortly after its arrival a second and largely similar spacecraft will impact Ceres to create an impact ejecta "plume" timed to enable a rendezvous and sampling by the primary spacecraft. This enables additional subsurface chemistry, volatile content and material characterization, and new science complementary to the Dawn spacecraft, the first to arrive at Ceres. Science requirements, candidate instruments, rendezvous trajectories, spacecraft design and comparison with Dawn science are detailed.

The Search for Sustainable Subsurface Habitats on Mars, and the Sampling of Impact Ejecta

NASA Astrophysics Data System (ADS)

Ivarsson, Magnus; Lindgren, Paula

2010-07-01

On Earth, the deep subsurface biosphere of both the oceanic and the continental crust is well known for surviving harsh conditions and environments characterized by high temperatures, high pressures, extreme pHs, and the absence of sunlight. The microorganisms of the terrestrial deep biosphere have an excellent capacity for adapting to changing geochemistry, as the alteration of the crust proceeds and the conditions of their habitats slowly change. Despite an almost complete isolation from surface conditions and the surface biosphere, the deep biosphere of the crustal rocks has endured over geologic time. This indicates that the deep biosphere is a self-sufficient system, independent of the global events that occur at the surface, such as impacts, glaciations, sea level fluctuations, and climate changes. With our sustainable terrestrial subsurface biosphere in mind, the subsurface on Mars has often been suggested as the most plausible place to search for fossil Martian life, or even present Martian life. Since the Martian surface is more or less sterile, subsurface settings are the only place on Mars where life could have been sustained over geologic time. To detect a deep biosphere in the Martian basement, drilling is a requirement. However, near future Mars sample return missions are limited by the mission's payload, which excludes heavy drilling equipment and restrict the missions to only dig the topmost meter of the Martian soil. Therefore, the sampling and analysis of Martian impact ejecta has been suggested as a way of accessing the deeper Martian subsurface without using heavy drilling equipment. Impact cratering is a natural geological process capable of excavating and exposing large amounts of rock material from great depths up to the surface. Several studies of terrestrial impact deposits show the preservation of pre-impact biosignatures, such as fossilized organisms and chemical biological markers. Therefore, if the Martian subsurface contains a record of life, it is reasonable to assume that biosignatures derived from the Martian subsurface could also be preserved in the Martian impact ejecta.

Subsurface warming across the Veluwe area (Netherlands) driven by climate change, urbanisation, groundwater abstraction and aquifer energy storage

NASA Astrophysics Data System (ADS)

Bense, Victor; de Kleijn, Christian; van Daal, Jonathan

2017-04-01

Atmospheric warming, urbanisation, land-use changes, groundwater abstraction and aquifer thermal energy storage can induce significant changes in the subsurface thermal regime. These need to better understood and monitored in order for humanity to make efficient use of the subsurface as a thermal reservoir, but also to understand how this space acts as a heat sink during the current warming of the climate. This work aims to improve our understanding of the relative importance, spatiotemporal characteristics and mechanisms of how various environmental processes and anthropogenic activities control changes in subsurface thermal regimes. Such changes are poignantly illustrated by temperature-depth profiles recently obtained in 30 boreholes upto several hundreds of meters deep that are present in the unconsolidated sedimentary aquifer system of the Veluwe area, Netherlands. A comparison to similar data collected in 1978-1980 shows that since then across the entire study area subsurface warming has occurred to depths upto 250 m. The availability of historic land-use maps, hydrogeological and meteorological data for this area allow for a detailed analysis of the observed subsurface warming patterns, which is aided by numerical models of coupled groundwater and heat flow. On a regional scale and across the entire first 100-150 m into the subsurface, the classic thermal signatures of variations in land-use, groundwater recharge and discharge fluxes, are increasingly overprinted by those of regional atmospheric warming and urbanisation. In the topographically higher, forested groundwater recharge areas groundwater is significantly cooler (upto 6 K) than in the open agricultural lands where groundwater is discharging. The presence of a thick (upto 30-40 m) unsaturated zone in the recharge area probably enhances this striking contrast in groundwater temperature in addition to the effects of groundwater recharge and the presence of forest. Locally and at larger depths, however, aquifer thermal storage activities and groundwater abstraction have a strong and probably more immediate role in altering the subsurface thermal regime.

Aseptically Sampled Organics in Subsurface Rocks From the Mars Analog Rio Tinto Experiment: An Analog For The Search for Deep Subsurface Life on Mars.}

NASA Astrophysics Data System (ADS)

Bonaccorsi, R.; Stoker, C. R.

2005-12-01

The subsurface is the key environment for searching for life on planets lacking surface life. Subsurface ecosystems are of great relevance to astrobiology including the search for past/present life on Mars. The surface of Mars has conditions preventing current life but the subsurface might preserve organics and even host some life [1]. The Mars-Analog-Rio-Tinto-Experiment (MARTE) is performing a simulation of a Mars drilling experiment. This comprises conventional and robotic drilling of cores in a volcanically-hosted-massive-pyrite deposit [2] from the Iberian Pyritic Belt (IBP) and life detection experiments applying anti-contamination protocols (e.g., ATP Luminometry assay). The RT is considered an important analog of the Sinus Meridiani site on Mars and an ideal model analog for a deep subsurface Martian environment. Former results from MARTE suggest the existence of a relatively complex subsurface life including aerobic and anaerobic chemoautotrophs and strict anaerobic methanogens sustained by Fe and S minerals in anoxic conditions. A key requirement for the analysis of a subsurface sample on Mars is a set of simple tests that can help determine if the sample contains organic material of biological origin, and its potential for retaining definitive biosignatures. We report here on the presence of bulk organic matter Corg (0.03-0.05 Wt%), and Ntot (0.01-0.04 Wt%) and amount of measured ATP (Lightning MVP, Biocontrol) in weathered rocks (tuffs, gossan, pyrite stockwork from Borehole #8; >166m). This provides key insight on the type of trophic system sustaining the subsurface biosphere (i.e., heterotrophs vs. autotrophs) at RT. ATP data (Relative-Luminosity-Units, RLU) provide information on possible contamination and distribution of viable biomass with core depth (BH#8, and BH#7, ~3m). Avg. 153 RLU, i.e., surface vs. center of core, suggest that cleaness/sterility can be maintained when using a simple sterile protocol under field conditions. Results from this research will support future drilling mission planned on Mars. [1] Boston, P.J., et al., 1992. Icarus 95,300-308; [2] Leistel et al., 1998.

Residues of endosulfan in surface and subsurface agricultural soil and its bioremediation.

PubMed

Odukkathil, Greeshma; Vasudevan, Namasivayam

2016-01-01

The persistence of many hydrophobic pesticides has been reported by various workers in various soil environments and its bioremediation is a major concern due to less bioavailability. In the present study, the pesticide residues in the surface and subsurface soil in an area of intense agricultural activity in Pakkam Village of Thiruvallur District, Tamilnadu, India, and its bioremediation using a novel bacterial consortium was investigated. Surface (0-15 cm) and subsurface soils (15-30 cm and 30-40 cm) were sampled, and pesticides in different layers of the soil were analyzed. Alpha endosulfan and beta endosulfan concentrations ranged from 1.42 to 3.4 mg/g and 1.28-3.1 mg/g in the surface soil, 0.6-1.4 mg/g and 0.3-0.6 mg/g in the subsurface soil (15-30 cm), and 0.9-1.5 mg/g and 0.34-1.3 mg/g in the subsurface soil (30-40 cm) respectively. Residues of other persistent pesticides were also detected in minor concentrations. These soil layers were subjected to bioremediation using a novel bacterial consortium under a simulated soil profile condition in a soil reactor. The complete removal of alpha and beta endosulfan was observed over 25 days. Residues of endosulfate were also detected during bioremediation, which was subsequently degraded on the 30th day. This study revealed the existence of endosulfan in the surface and subsurface soils and also proved that the removal of such a ubiquitous pesticide in the surface and subsurface environment can be achieved in the field by bioaugumenting a biosurfactant-producing bacterial consortium that degrades pesticides. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antarctic Mirabilite Mounds as Mars Analogs: The Lewis Cliffs Ice Tongue Revisited

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Sun, Tao; Niles, Paul B.; Harvey, Ralph P.; Bish, David L.; Tonui, Eric

2012-01-01

It has been proposed, based on geomorphic and geochemical arguments, that subsurface water has played an important role in the history of water on the planet Mars [1]. Subsurface water, if present, could provide a protected and long lived environment for potential life. Discovery of gullies [2] and recurring slopes [3] on Mars suggest the potential for subsurface liquid water or brines. Recent attention has also focused on small (< approx. 1km dia.) mound-like geomorphic features discovered within the mid to high latitudes on the surface of Mars which may be caused by eruptions of subsurface fluids [4, 5]. We have identified massive but highly localized Na-sulfate deposits (mirabilite mounds, Na2SO4 .10H2O) that may be derived from subsurface fluids and may provide insight into the processes associated with subsurface fluids on Mars. The mounds are found on the end moraine of the Lewis Cliffs Ice Tongue (LCIT) [6] in the Transantarctic Mountains, Antarctica, and are potential terrestrial analogs for mounds observed on the martian surface. The following characteristics distinguish LCIT evaporite mounds from other evaporite mounds found in Antarctic coastal environments and/or the McMurdo Dry Valleys: (1) much greater distance from the open ocean (approx.500 km); (2) higher elevation (approx.2200 meters); and (3) colder average annual temperature (average annual temperature = -30 C for LCIT [7] vs. 20 C at sea level in the McMurdo region [8]. Furthermore, the recent detection of subsurface water ice (inferred as debris-covered glacial ice) by the Mars Reconnaissance Orbiter [9] supports the use of an Antarctic glacial environment, particularly with respect to the mirabilite deposits described in this work, as an ideal terrestrial analog for understanding the geochemistry associated with near-surface martian processes. S and O isotopic compositions.

Understanding Subsurface Geoelectrical and Structural Constrains for Low Frequency Radar Sounding of Jovian Satellites

NASA Astrophysics Data System (ADS)

Heggy, Essam; Bruzzone, Lorenzo; Beck, Pierre; Doute, Sylvain; Gim, Youngyu; Herique, Alain; Kofman, Wlodek; Orosei, Roberto; Plaut, Jeffery; Rosen, Paul; Seu, Roberto

2010-05-01

Thermally stable Ice sheets on earth are known to be among the most favorable geophysical contexts for deep subsurface sounding radars. Penetrations ranging from few to several hundreds of meters have been observed at 10 to 60 MHz when sounding homogenous and pure ice sheets in Antarctica and in Alaskan glaciers. Unlike the terrestrial case, ice sheets on Jovian satellites are older formations with a more complex matrix of mineral inclusions with an even three dimensional distribution on the surface and subsurface that is yet to be understood in order to quantify its effect on the dielectric attenuation at the experiment sounding frequencies. Moreover, ridges, tectonic and shock features, may results in a complex and heterogeneous subsurface structure that can induce scattering attenuation with different amplitudes depending on the subsurface heterogeneity levels. Such attenuation phenomena's has to be accounted in the instrument design and future data analysis in order to optimize the science return, reduce mission risk and define proper operation modes. In order to address those challenges in the current performance studies and instrument design of the proposed radar sounding experiments, we present an attempt to quantify both the dielectric and scattering losses on both icy satellites, Ganymede and Europa, based on experimental dielectric characterization of relevant icy-dust mixtures samples, field work from analog environment and radar propagation simulations in parametric subsurface geophysical models representing potential geological scenarios of the two Jovian satellites. Our preliminary results suggest that the use of a dual band radar enable to overcome several of these constrains and reduces ambiguities associated subsurface interface mapping. Acknowledgement. This research is carried out by the Jet Propulsion Laboratory/Caltech, under a grant from the National Aeronautics and Space Administration.

Combined Geothermal Potential of Subsurface Urban Heat Islands

NASA Astrophysics Data System (ADS)

Benz, Susanne; Bayer, Peter; Menberg, Kathrin; Blum, Philipp

2016-04-01

The subsurface urban heat island (SUHI) can be seen as a geothermal potential in form of elevated groundwater temperatures caused by anthropogenic heat fluxes into the subsurface. In this study, these fluxes are quantified for an annual timeframe in two German cities, Karlsruhe and Cologne. Our two-dimensional (2D) statistical analytical model determines the renewable and sustainable geothermal potential caused by six vertical anthropogenic heat fluxes into the subsurface: from (1) elevated ground surface temperatures, (2) basements, (3) sewage systems, (4) sewage leakage, (5) subway tunnels, and (6) district heating networks. The results show that at present 2.15 ± 1.42 PJ and 0.99 ± 0.32 PJ of heat are annually transported into the shallow groundwater of Karlsruhe and Cologne, respectively, due to anthropogenic heat fluxes into the subsurface. This is sufficient to sustainably cover 32% and 9% of the annual residential space heating demand of Karlsruhe and Cologne, respectively. However, most of the discussed anthropogenic fluxes into the subsurface are conductive heat fluxes and therefore dependent on the groundwater temperature itself. Accordingly, a decrease in groundwater temperature back to its natural (rural) state, achieved through the use of geothermal heat pumps, will increase these fluxes and with them the sustainable potential. Hence, we propose the introduction of a combined geothermal potential that maximizes the sustainability of urban shallow geothermal energy use and the efficiency of shallow geothermal systems by balancing groundwater temperature with anthropogenic heat fluxes into the subsurface. This will be a key element in the development of a demand-oriented, cost-efficient geothermal management tool with an additional focus on the sustainability of the urban heat sources.

Object detection with a multistatic array using singular value decomposition

DOEpatents

Hallquist, Aaron T.; Chambers, David H.

2014-07-01

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across a surface and that travels down the surface. The detection system converts the return signals from a time domain to a frequency domain, resulting in frequency return signals. The detection system then performs a singular value decomposition for each frequency to identify singular values for each frequency. The detection system then detects the presence of a subsurface object based on a comparison of the identified singular values to expected singular values when no subsurface object is present.

Coupling LaGrit unstructured mesh generation and model setup with TOUGH2 flow and transport: A case study

DOE PAGES

Sentis, Manuel Lorenzo; Gable, Carl W.

2017-06-15

Furthermore, there are many applications in science and engineering modeling where an accurate representation of a complex model geometry in the form of a mesh is important. In applications of flow and transport in subsurface porous media, this is manifest in models that must capture complex geologic stratigraphy, structure (faults, folds, erosion, deposition) and infrastructure (tunnels, boreholes, excavations). Model setup, defined as the activities of geometry definition, mesh generation (creation, optimization, modification, refine, de-refine, smooth), assigning material properties, initial conditions and boundary conditions requires specialized software tools to automate and streamline the process. In addition, some model setup tools willmore » provide more utility if they are designed to interface with and meet the needs of a particular flow and transport software suite. A control volume discretization that uses a two point flux approximation is for example most accurate when the underlying control volumes are 2D or 3D Voronoi tessellations. In this paper we will present the coupling of LaGriT, a mesh generation and model setup software suite and TOUGH2 to model subsurface flow problems and we show an example of how LaGriT can be used as a model setup tool for the generation of a Voronoi mesh for the simulation program TOUGH2. To generate the MESH file for TOUGH2 from the LaGriT output a standalone module Lagrit2Tough2 was developed, which is presented here and will be included in a future release of LaGriT. Here in this paper an alternative method to generate a Voronoi mesh for TOUGH2 with LaGriT is presented and thanks to the modular and command based structure of LaGriT this method is well suited to generating a mesh for complex models.« less

Coupling LaGrit unstructured mesh generation and model setup with TOUGH2 flow and transport: A case study

NASA Astrophysics Data System (ADS)

Sentís, Manuel Lorenzo; Gable, Carl W.

2017-11-01

There are many applications in science and engineering modeling where an accurate representation of a complex model geometry in the form of a mesh is important. In applications of flow and transport in subsurface porous media, this is manifest in models that must capture complex geologic stratigraphy, structure (faults, folds, erosion, deposition) and infrastructure (tunnels, boreholes, excavations). Model setup, defined as the activities of geometry definition, mesh generation (creation, optimization, modification, refine, de-refine, smooth), assigning material properties, initial conditions and boundary conditions requires specialized software tools to automate and streamline the process. In addition, some model setup tools will provide more utility if they are designed to interface with and meet the needs of a particular flow and transport software suite. A control volume discretization that uses a two point flux approximation is for example most accurate when the underlying control volumes are 2D or 3D Voronoi tessellations. In this paper we will present the coupling of LaGriT, a mesh generation and model setup software suite and TOUGH2 (Pruess et al., 1999) to model subsurface flow problems and we show an example of how LaGriT can be used as a model setup tool for the generation of a Voronoi mesh for the simulation program TOUGH2. To generate the MESH file for TOUGH2 from the LaGriT output a standalone module Lagrit2Tough2 was developed, which is presented here and will be included in a future release of LaGriT. In this paper an alternative method to generate a Voronoi mesh for TOUGH2 with LaGriT is presented and thanks to the modular and command based structure of LaGriT this method is well suited to generating a mesh for complex models.

High CO2 subsurface environment enriches for novel microbial lineages capable of autotrophic carbon fixation

NASA Astrophysics Data System (ADS)

Probst, A. J.; Jerett, J.; Castelle, C. J.; Thomas, B. C.; Sharon, I.; Brown, C. T.; Anantharaman, K.; Emerson, J. B.; Hernsdorf, A. W.; Amano, Y.; Suzuki, Y.; Tringe, S. G.; Woyke, T.; Banfield, J. F.

2015-12-01

Subsurface environments span the planet but remain little understood from the perspective of the capacity of the resident organisms to fix CO2. Here we investigated the autotrophic capacity of microbial communities in range of a high-CO2 subsurface environments via analysis of 250 near-complete microbial genomes (151 of them from distinct species) that represent the most abundant organisms over a subsurface depth transect. More than one third of the genomes belonged to the so-called candidate phyla radiation (CPR), which have limited metabolic capabilities. Approximately 30% of the community members are autotrophs that comprise 70% of the microbiome with metabolism likely supported by sulfur and nitrogen respiration. Of the carbon fixation pathways, the Calvin Benson Basham Cycle was most common, but the Wood-Ljungdhal pathway was present in the greatest phylogenetic diversity of organisms. Unexpectedly, one organism from a novel phylum sibling to the CPR is predicted to fix carbon by the reverse TCA cycle. The genome of the most abundant organism, an archaeon designated "Candidatus Altiarchaeum hamiconexum", was also found in subsurface samples from other continents including Europe and Asia. The archaeon was proven to be a carbon fixer using a novel reductive acetyl-CoA pathway. These results provide evidence that carbon dioxide is the major carbon source in these environments and suggest that autotrophy in the subsurface represents a substantial carbon dioxide sink affecting the global carbon cycle.

Resource Prospector: Evaluating the ISRU Potential of the Lunar Poles

NASA Technical Reports Server (NTRS)

Colaprete, A.; Elphic, R.; Andrews, D.; Trimble, J.; Bluethmann, B.; Quinn, J.; Chavers, G.

2017-01-01

Resource Prospector (RP) is a lunar volatiles prospecting mission being developed for potential flight in CY2021-2022. The mission includes a rover-borne payload that (1) can locate surface and near-subsurface volatiles, (2) excavate and analyze samples of the volatile-bearing regolith, and (3) demonstrate the form, extractability and usefulness of the materials. The primary mission goal for RP is to evaluate the In-Situ Resource Utilization (ISRU) potential of the lunar poles.

The Search for Carbonates on Mars

NASA Technical Reports Server (NTRS)

Farmer, Jack D.; DesMarais, David J.; Morrison, David (Technical Monitor)

1994-01-01

Liquid water is presently unstable at the Martian surface, where the mean atmospheric pressure is 6 mbar (due to CO2) and the winter diurnal temperature ranges from 150 K at the pole to 220 K at the equator. Liquid water is widely regarded as a basic requirement for living systems, suggesting that life as we know it is not possible in present surface environments on Mars. However, life may survive within "oases" where liquid water is present. Potential oases on Mars include subsurface hydrothermal systems or deeply buried aquifers where chemoautolithotrophic microorganisms may exist. Potential metabolic strategies for primary production in such environments on Mars (and for the microbial mediation of geologic processes!) encompass the full range presently known for subsurface environments on the Earth (e.g. sulphate reduction, methanogenesis, acetogenesis, etc).

Induced seismicity constraints on subsurface geological structure, Paradox Valley, Colorado

NASA Astrophysics Data System (ADS)

Block, Lisa V.; Wood, Christopher K.; Yeck, William L.; King, Vanessa M.

2015-02-01

Precise relative hypocentres of seismic events induced by long-term fluid injection at the Paradox Valley Unit (PVU) brine disposal well provide constraints on the subsurface geological structure and compliment information available from deep seismic reflection and well data. We use the 3-D spatial distribution of the hypocentres to refine the locations, strikes, and throws of subsurface faults interpre­ted previously from geophysical surveys and to infer the existence of previously unidentified subsurface faults. From distinct epicentre lineations and focal mechanism trends, we identify a set of conjugate fracture orientations consistent with shear-slip reactivation of late-Palaeozoic fractures over a widespread area, as well as an additional fracture orientation present only near the injection well. We propose simple Mohr-Coulomb fracture models to explain these observations. The observation that induced seismicity preferentially occurs along one of the identified conjugate fracture orientations can be explained by a rotation in the direction of the regional maximum compressive stress from the time when the fractures were formed to the present. Shear slip along the third fracture orientation observed near the injection well is inconsistent with the current regional stress field and suggests a local rotation of the horizontal stresses. The detailed subsurface model produced by this analysis provides important insights for anticipating spatial patterns of future induced seismicity and for evaluation of possible additional injection well sites that are likely to be seismically and hydrologically isolated from the current well. In addition, the interpreted fault patterns provide constraints for estimating the maximum magnitude earthquake that may be induced, and for building geomechanical models to simulate pore pressure diffusion, stress changes and earthquake triggering.

Capabilities of seismic and georadar 2D/3D imaging of shallow subsurface of transport route using the Seismobile system

NASA Astrophysics Data System (ADS)

Pilecki, Zenon; Isakow, Zbigniew; Czarny, Rafał; Pilecka, Elżbieta; Harba, Paulina; Barnaś, Maciej

2017-08-01

In this work, the capabilities of the Seismobile system for shallow subsurface imaging of transport routes, such as roads, railways, and airport runways, in different geological conditions were presented. The Seismobile system combines the advantages of seismic profiling using landstreamer and georadar (GPR) profiling. It consists of up to four seismic measuring lines and carriage with a suspended GPR antenna. Shallow subsurface recognition may be achieved to a maximum width of 10.5 m for a distance of 3.5 m between the measurement lines. GPR measurement is performed in the axis of the construction. Seismobile allows the measurement time, labour and costs to be reduced due to easy technique of its installation, remote data transmission from geophones to accompanying measuring modules, automated location of the system based on GPS and a highly automated method of seismic wave excitation. In this paper, the results of field tests carried out in different geological conditions were presented. The methodologies of acquisition, processing and interpretation of seismic and GPR measurements were broadly described. Seismograms and its spectrum registered by Seismobile system were compared to the ones registered by Geode seismograph of Geometrix. Seismic data processing and interpretation software allows for the obtaining of 2D/3D models of P- and S-wave velocities. Combined seismic and GPR results achieved sufficient imaging of shallow subsurface to a depth of over a dozen metres. The obtained geophysical information correlated with geological information from the boreholes with good quality. The results of performed tests proved the efficiency of the Seismobile system in seismic and GPR imaging of a shallow subsurface of transport routes under compound conditions.

Tropical North Atlantic subsurface warming events as a fingerprint for AMOC variability during Marine Isotope Stage 3

NASA Astrophysics Data System (ADS)

Parker, Andrew O.; Schmidt, Matthew W.; Chang, Ping

2015-11-01

The role of Atlantic Meridional Overturning Circulation (AMOC) as the driver of Dansgaard-Oeschger (DO) variability that characterized Marine Isotope Stage 3 (MIS 3) has long been hypothesized. Although there is ample proxy evidence suggesting that DO events were robust features of glacial climate, there is little data supporting a link with AMOC. Recently, modeling studies and subsurface temperature reconstructions have suggested that subsurface warming across the tropical North Atlantic can be used to fingerprint a weakened AMOC during the deglacial because a reduction in the strength of the western boundary current allows warm salinity maximum water of the subtropical gyre to enter the deep tropics. To determine if AMOC variability played a role during the DO cycles of MIS 3, we present new, high-resolution Mg/Ca and δ18O records spanning 24-52 kyr from the near-surface dwelling planktonic foraminifera Globigerinoides ruber and the lower thermocline dwelling planktonic foraminifera Globorotalia truncatulinoides in Southern Caribbean core VM12-107 (11.33°N, 66.63°W, 1079 m depth). Our subsurface Mg/Ca record reveals abrupt increases in Mg/Ca ratios (the largest equal to a 4°C warming) during the interstadial-stadial transition of most DO events during this period. This change is consistent with reconstructions of subsurface warming events associated with cold events across the deglacial using the same core. Additionally, our data support the conclusion reached by a recently published study from the Florida Straits that AMOC did not undergo significant reductions during Heinrich events 2 and 3. This record presents some of the first high-resolution marine sediment derived evidence for variable AMOC during MIS 3.

Predictability of Subsurface Temperature and the AMOC

NASA Astrophysics Data System (ADS)

Chang, Y.; Schubert, S. D.

2013-12-01

GEOS 5 coupled model is extensively used for experimental decadal climate prediction. Understanding the limits of decadal ocean predictability is critical for making progress in these efforts. Using this model, we study the subsurface temperature initial value predictability, the variability of the Atlantic meridional overturning circulation (AMOC) and its impacts on the global climate. Our approach is to utilize the idealized data assimilation technology developed at the GMAO. The technique 'replay' allows us to assess, for example, the impact of the surface wind stresses and/or precipitation on the ocean in a very well controlled environment. By running the coupled model in replay mode we can in fact constrain the model using any existing reanalysis data set. We replay the model constraining (nudging) it to the MERRA reanalysis in various fields from 1948-2012. The fields, u,v,T,q,ps, are adjusted towards the 6-hourly analyzed fields in atmosphere. The simulated AMOC variability is studied with a 400-year-long segment of replay integration. The 84 cases of 10-year hindcasts are initialized from 4 different replay cycles. Here, the variability and predictability are examined further by a measure to quantify how much the subsurface temperature and AMOC variability has been influenced by atmospheric forcing and by ocean internal variability. The simulated impact of the AMOC on the multi-decadal variability of the SST, sea surface height (SSH) and sea ice extent is also studied.

A seismic search for the paleoshorelines of Lake Otero beneath White Sands Dune Field, New Mexico

NASA Astrophysics Data System (ADS)

Wagner, P. F.; Reece, R.; Ewing, R. C.

2014-12-01

The Tularosa Basin, which now houses White Sands Dune Field, was once occupied by Pleistocene Lake Otero. Several paleoshorelines of Lake Otero have been identified throughout the basin by field surveys and remote sensing using digital elevation models. Up to four shorelines may be buried beneath White Sands Dune Field and it has been posited that the current upwind margin of White Sands coincides with a one of these shorelines. Here we employ a novel geophysical instrument and method to image the subsurface: the seismic land streamer. The land streamer utilizes weighted base plates and one-component vertical geophones in a towed array. With a seisgun acoustic source, we imaged in the Alkali Flats area near the upwind margin, one potential location of paleoshorelines, as well as the Film Lot closer to the center of the dune field. Surfaces in both locations are indurated gypsum playa, which made seismic imaging possible and successful. We collected one SW-NE trending seismic line at each location, which matches the dominant wind and dune migration directions. Based on initial data analysis we find some subsurface structure that may coincide with the paleo lake bed of Lake Otero. The successful demonstration of this new method provides the foundation for an expanded regional subsurface study to image the strata and structure of the Tularosa Basin.

Lunar regolith stratigraphy analysis based on the simulation of lunar penetrating radar signals

NASA Astrophysics Data System (ADS)

Lai, Jialong; Xu, Yi; Zhang, Xiaoping; Tang, Zesheng

2017-11-01

The thickness of lunar regolith is an important index of evaluating the quantity of lunar resources such as 3He and relative geologic ages. Lunar penetrating radar (LPR) experiment of Chang'E-3 mission provided an opportunity of in situ lunar subsurface structure measurement in the northern mare imbrium area. However, prior work on analyzing LPR data obtained quite different conclusions of lunar regolith structure mainly because of the missing of clear interface reflectors in radar image. In this paper, we utilized finite-difference time-domain (FDTD) method and three models of regolith structures with different rock density, number of layers, shapes of interfaces, and etc. to simulate the LPR signals for the interpretation of radar image. The simulation results demonstrate that the scattering signals caused by numerous buried rocks in the regolith can mask the horizontal reflectors, and the die-out of radar echo does not indicate the bottom of lunar regolith layer and data processing such as migration method could recover some of the subsurface information but also result in fake signals. Based on analysis of simulation results, we conclude that LPR results uncover the subsurface layered structure containing the rework zone with multiple ejecta blankets of small crater, the ejecta blanket of Chang'E-3 crater, and the transition zone and estimate the thickness of the detected layer is about 3.25 m.

DAS Microseismic and Strain Monitoring During Hydraulic Fracturing

NASA Astrophysics Data System (ADS)

Kahn, D.; Karrenbach, M. H.; Cole, S.; Boone, K.; Ridge, A.; Rich, J.; Langton, D.; Silver, K.

2017-12-01

Hydraulic fracturing operations in unconventional subsurface reservoirs are typically monitored using geophones located either at the surface or in adjacent wellbores. A novel approach to record hydraulic stimulations utilizes fiber-optic Distributed Acoustic Sensing (DAS). A fiber-optic cable was installed in a treatment well in a subsurface reservoir (Meramec formation). DAS data were recorded during fluid injection of same fibered well and also during injection into a nearby treatment well at a distance of 350m. For both scenarios the DAS sensing array consisted of approximately 1000 channels at a fine spatial and temporal sampling and with a large sensing aperture. Thus, the full strain wave field is measured along the borehole over its entire length. A variety of physical effects, such as temperature, low-frequency strain and microseismicity were measured and correlated with the treatment program during hydraulic fracturing of the wells. These physical effects occur at various frequency scales and produce complementary measurements. Microseismic events in the magnitude range of -0.5 and -2.0 at a maximum distance of 500m were observed and analyzed for recordings from the fiber-equipped treatment well and also neighboring treatment well. The analysis of this DAS data set demonstrates that current fiber-optic sensing technology can provide enough sensitivity to detect a significant number of microseismic events and that these events can be integrated with temperature and strain measurements for an improved subsurface reservoir description.

Detection of Subsurface Defects in Levees in Correlation to Weather Conditions Utilizing Ground Penetrating Radar

NASA Astrophysics Data System (ADS)

Martinez, I. A.; Eisenmann, D.

2012-12-01

Ground Penetrating Radar (GPR) has been used for many years in successful subsurface detection of conductive and non-conductive objects in all types of material including different soils and concrete. Typical defect detection is based on subjective examination of processed scans using data collection and analysis software to acquire and analyze the data, often requiring a developed expertise or an awareness of how a GPR works while collecting data. Processing programs, such as GSSI's RADAN analysis software are then used to validate the collected information. Iowa State University's Center for Nondestructive Evaluation (CNDE) has built a test site, resembling a typical levee used near rivers, which contains known sub-surface targets of varying size, depth, and conductivity. Scientist at CNDE have developed software with the enhanced capabilities, to decipher a hyperbola's magnitude and amplitude for GPR signal processing. With this enhanced capability, the signal processing and defect detection capabilities for GPR have the potential to be greatly enhanced. This study will examine the effects of test parameters, antenna frequency (400MHz), data manipulation methods (which include data filters and restricting the range of depth in which the chosen antenna's signal can reach), and real-world conditions using this test site (such as varying weather conditions) , with the goal of improving GPR tests sensitivity for differing soil conditions.

Transmission mode acoustic time-reversal imaging for nondestructive evaluation

NASA Astrophysics Data System (ADS)

Lehman, Sean K.; Devaney, Anthony J.

2002-11-01

In previous ASA meetings and JASA papers, the extended and formalized theory of transmission mode time reversal in which the transceivers are noncoincident was presented. When combined with the subspace concepts of a generalized MUltiple SIgnal Classification (MUSIC) algorithm, this theory is used to form super-resolution images of scatterers buried in a medium. These techniques are now applied to ultrasonic nondestructive evaluation (NDE) of parts, and shallow subsurface seismic imaging. Results are presented of NDE experiments on metal and epoxy blocks using data collected from an adaptive ultrasonic array, that is, a ''time-reversal machine,'' at Lawrence Livermore National Laboratory. Also presented are the results of seismo-acoustic subsurface probing of buried hazardous waste pits at the Idaho National Engineering and Environmental Laboratory. [Work performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.] [Work supported in part by CenSSIS, the Center for Subsurface Sensing and Imaging Systems, under the Engineering Research Centers Program of the NSF (award number EEC-9986821) as well as from Air Force Contracts No. F41624-99-D6002 and No. F49620-99-C0013.

Three-dimensional vapor intrusion modeling approach that combines wind and stack effects on indoor, atmospheric, and subsurface domains.

PubMed

Shirazi, Elham; Pennell, Kelly G

2017-12-13

Vapor intrusion (IV) exposure risks are difficult to characterize due to the role of atmospheric, building and subsurface processes. This study presents a three-dimensional VI model that extends the common subsurface fate and transport equations to incorporate wind and stack effects on indoor air pressure, building air exchange rate (AER) and indoor contaminant concentration to improve VI exposure risk estimates. The model incorporates three modeling programs: (1) COMSOL Multiphysics to model subsurface fate and transport processes, (2) CFD0 to model atmospheric air flow around the building, and (3) CONTAM to model indoor air quality. The combined VI model predicts AER values, zonal indoor air pressures and zonal indoor air contaminant concentrations as a function of wind speed, wind direction and outdoor and indoor temperature. Steady state modeling results for a single-story building with a basement demonstrate that wind speed, wind direction and opening locations in a building play important roles in changing the AER, indoor air pressure, and indoor air contaminant concentration. Calculated indoor air pressures ranged from approximately -10 Pa to +4 Pa depending on weather conditions and building characteristics. AER values, mass entry rates and indoor air concentrations vary depending on weather conditions and building characteristics. The presented modeling approach can be used to investigate the relationship between building features, AER, building pressures, soil gas concentrations, indoor air concentrations and VI exposure risks.

Ultrahigh-Resolution 3-Dimensional Seismic Imaging of Seeps from the Continental Slope of the Northern Gulf of Mexico: Subsurface, Seafloor and Into the Water Column

NASA Astrophysics Data System (ADS)

Brookshire, B. N., Jr.; Mattox, B. A.; Parish, A. E.; Burks, A. G.

2016-02-01

Utilizing recently advanced ultrahigh-resolution 3-dimensional (UHR3D) seismic tools we have imaged the seafloor geomorphology and associated subsurface aspects of seep related expulsion features along the continental slope of the northern Gulf of Mexico with unprecedented clarity and continuity. Over an area of approximately 400 km2, over 50 discrete features were identified and three general seafloor geomorphologies indicative of seep activity including mounds, depressions and bathymetrically complex features were quantitatively characterized. Moreover, areas of high seafloor reflectivity indicative of mineralization and areas of coherent seismic amplitude anomalies in the near-seafloor water column indicative of active gas expulsion were identified. In association with these features, shallow source gas accumulations and migration pathways based on salt related stratigraphic uplift and faulting were imaged. Shallow, bottom simulating reflectors (BSRs) interpreted to be free gas trapped under near seafloor gas hydrate accumulations were very clearly imaged.

Compatibility of Surfactants and Thermally Activated Persulfate for Enhanced Subsurface Remediation.

PubMed

Wang, Li; Peng, Libin; Xie, Liling; Deng, Peiyan; Deng, Dayi

2017-06-20

Limited aqueous availability of hydrophobic organic contaminants and nonaqueous phase liquids in subsurface environment may seriously impair the effectiveness of traditional in situ chemical oxidation (ISCO). To tackle the issue, a combination of surfactants and thermally activated persulfate was proposed to enhance the aqueous availability and consequent oxidation of organic contaminants. The compatibility of eight representative nonionic, monovalent anionic, and divalent anionic surfactants with persulfate at various temperatures was first studied, to identify suitable surfactants that have high aqueous stability and low oxidant demands to couple with thermally activated persulfate. C 12 -MADS (sodium dodecyl diphenyl ether disulfonate, a representative divalent anionic surfactant) stands out as the most compatible surfactant. Batch treatability study with coal tar, an example of challenging scenarios for traditional ISCO, was then conducted. The results show that C 12 -MADS can significantly enhance not only the oxidation of polyaromatic hydrocarbons contained in coal tar but also oxidant utilization efficiency, indicating the potential of the proposed coupling process for the treatment of organic contaminants with low aqueous availability.

An intelligent subsurface buoy design for measuring ocean ambient noise

NASA Astrophysics Data System (ADS)

Li, Bing; Wang, Lei

2012-11-01

A type of ultra-low power subsurface buoy system is designed to measure and record ocean ambient noise data. The buoy utilizes a vector hydrophone (pass band 20Hz-1.2kHz) and a 6-element vertical hydrophone array (pass band 20Hz-2kHz) to measure ocean ambient noise. The acoustic signals are passed through an automatically modified gain, a band pass filter, and an analog-to-digital (A/D) conversion module. They are then stored in high-capacity flash memory. In order to identify the direction of noise source, the vector sensor measuring system has integrated an electric-magnetic compass. The system provides a low-rate underwater acoustic communication system which is used to report the buoy state information and a high-speed USB interface which is used to retrieve the recorded data on deck. The whole system weighs about 125kg and can operate autonomously for more than 72 hours. The system's main architecture and the sea-trial test results are provided in this paper.

Automated benthic counting of living and non-living components in Ngedarrak Reef, Palau via subsurface underwater video.

PubMed

Marcos, Ma Shiela Angeli; David, Laura; Peñaflor, Eileen; Ticzon, Victor; Soriano, Maricor

2008-10-01

We introduce an automated benthic counting system in application for rapid reef assessment that utilizes computer vision on subsurface underwater reef video. Video acquisition was executed by lowering a submersible bullet-type camera from a motor boat while moving across the reef area. A GPS and echo sounder were linked to the video recorder to record bathymetry and location points. Analysis of living and non-living components was implemented through image color and texture feature extraction from the reef video frames and classification via Linear Discriminant Analysis. Compared to common rapid reef assessment protocols, our system can perform fine scale data acquisition and processing in one day. Reef video was acquired in Ngedarrak Reef, Koror, Republic of Palau. Overall success performance ranges from 60% to 77% for depths of 1 to 3 m. The development of an automated rapid reef classification system is most promising for reef studies that need fast and frequent data acquisition of percent cover of living and nonliving components.

The deep-subsurface sulfate reducer Desulfotomaculum kuznetsovii employs two methanol-degrading pathways.

PubMed

Sousa, Diana Z; Visser, Michael; van Gelder, Antonie H; Boeren, Sjef; Pieterse, Mervin M; Pinkse, Martijn W H; Verhaert, Peter D E M; Vogt, Carsten; Franke, Steffi; Kümmel, Steffen; Stams, Alfons J M

2018-01-16

Methanol is generally metabolized through a pathway initiated by a cobalamine-containing methanol methyltransferase by anaerobic methylotrophs (such as methanogens and acetogens), or through oxidation to formaldehyde using a methanol dehydrogenase by aerobes. Methanol is an important substrate in deep-subsurface environments, where thermophilic sulfate-reducing bacteria of the genus Desulfotomaculum have key roles. Here, we study the methanol metabolism of Desulfotomaculum kuznetsovii strain 17 T , isolated from a 3000-m deep geothermal water reservoir. We use proteomics to analyze cells grown with methanol and sulfate in the presence and absence of cobalt and vitamin B12. The results indicate the presence of two methanol-degrading pathways in D. kuznetsovii, a cobalt-dependent methanol methyltransferase and a cobalt-independent methanol dehydrogenase, which is further confirmed by stable isotope fractionation. This is the first report of a microorganism utilizing two distinct methanol conversion pathways. We hypothesize that this gives D. kuznetsovii a competitive advantage in its natural environment.

The Western Noachis Terra Chloride Deposits: An Improved Characterization of the Proposed Human Exploration Zone

NASA Astrophysics Data System (ADS)

Hill, J. R.; Plaut, J. J.; Christensen, P. R.

2016-12-01

At the First Landing Site and Exploration Zone Workshop for Human Missions to the Surface of Mars (Oct 27-30, 2015, Houston, TX), planetary scientists, students and members of the public proposed forty-seven sites that meet the engineering requirements for a human mission and would also allow astronauts to investigate important scientific questions while on the surface. The chloride deposits in western Noachis Terra at -37.2°N, 350.5°E were proposed as a potential exploration zone due to their proximity to craters containing glacier-like forms and imperfectly-formed concentric crater fill. The high astrobiological preservation potential of the chloride deposits exposed on the surface would allow astronauts to investigate the past habitability of a well-preserved Noachian fluvial system, while the subsurface ice features suggest astronauts would have relatively easy access to enough water to meet the requirements of NASA's current baseline mission architecture. Since the workshop, the proposed exploration zone has been further characterized using additional datasets, as well as new data collected by the Mars Reconnaissance Orbiter as part of the exploration zone data acquisition effort organized by NASA's Human Landing Sites Study (HLS2) team. First, SHARAD radar data were used to constrain the subsurface structure of the imperfectly-formed concentric crater fill within the two large craters, which makes a more accurate assessment of the potential subsurface water ice resources possible. Second, newly acquired HiRISE images were used to better assess the traversability of the terrain between the habitation zone and the primary resource and science regions-of-interest (ROIs). And third, the exploration zone was shifted in order to place the central landing site closer to potential subsurface water ice resources. Although this would require crews to travel further to investigate the chloride deposits, it reduces the distance between the subsurface water ice locations and the central habitation zone, where the excavated water would be processed and utilized. The analysis of this additional data has further demonstrated that the western Noachis Terra chloride deposits are an ideal location for astronauts to safely and effectively conduct astrobiological investigations on the Martian surface.

Subsurface water and clay mineral formation during the early history of Mars.

PubMed

Ehlmann, Bethany L; Mustard, John F; Murchie, Scott L; Bibring, Jean-Pierre; Meunier, Alain; Fraeman, Abigail A; Langevin, Yves

2011-11-02

Clay minerals, recently discovered to be widespread in Mars's Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago. Analysis of how they formed should indicate what environmental conditions prevailed on early Mars. If clays formed near the surface by weathering, as is common on Earth, their presence would indicate past surface conditions warmer and wetter than at present. However, available data instead indicate substantial Martian clay formation by hydrothermal groundwater circulation and a Noachian rock record dominated by evidence of subsurface waters. Cold, arid conditions with only transient surface water may have characterized Mars's surface for over 4 billion years, since the early-Noachian period, and the longest-duration aqueous, potentially habitable environments may have been in the subsurface.

Sorting Out the Ocean Crust Deep Biosphere with Single Cell Omics Approaches

NASA Astrophysics Data System (ADS)

Orcutt, B.; D'Angelo, T.; Goordial, J.; Jones, R. M.; Carr, S. A.

2017-12-01

Although oceanic crust comprises a large habitat for subsurface life, the structure, function, and dynamics of microbial communities living on rocks in the subsurface are poorly understood. Single cell level approaches can overcome limitations of low biomass in subsurface systems. Coupled with incubation experiments with amino acid orthologs, single cell level sorting can reveal high resolution information about identity, functional potential, and growth. Leveraging collaboration with the Single Cell Genomics Center and the Facility for Aquatic Cytometry at Bigelow Laboratory, we present recent results from single cell level sorting and -omics sequencing from several crustal environments, including the Atlantis Massif and the Juan de Fuca Ridge flank. We will also highlight new experiments conducted with samples recovered from the flank of the Mid-Atlantic Ridge.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qafoku, Nikolla; Sahajpal, Rahul

Chromium-contaminated subsurface sites are common throughout the globe. In this chapter the discussion will be focused on one Cr-contaminated, i.e., Hanford site, WA, USA. The chapter summarizes the work conducted at this site to study contaminant Cr6+ fate and behavior under conditions imposed by different waste chemistries ranging from acidic to hyperalkaline. The objectives of this chapter are to present an overview of different aspects of Cr interaction with minerals; present evidence of similar and contrasting Cr6+ reactions, processes and attenuation mechanisms operating in subsurface environments under different conditions imposed by acidic, neutral and alkaline waste liquids; provide inputs tomore » conceptual Cr geochemical models (either site specific or general and suitable for many contaminated sites); present ideas on potential remedial measures. The insights presented and discussed in this chapter should be useful for other Cr contaminated sites across the world.« less

Ocean Nitrogen Isotopic Change in the Early Eocene

NASA Astrophysics Data System (ADS)

Kast, E.; Stolper, D. A.; Higgins, J. A.; Ren, H. A.; Wang, X. T.; Sigman, D. M.

2017-12-01

The long term variability of the marine nitrogen (N) cycle is an open question. The Cenozoic provides a well-studied framework for investigating the marine N cycle over long time scales and across large climate transitions. However, only sparse bulk Cenozoic sediment δ15N data exist, the utility of which for reconstructing environmental conditions is unclear. We present a record of foraminifera-bound organic matter δ15N from the Paleocene to late Eocene. At three distant sites, foraminifera-bound δ15N decreases dramatically between 56 Ma and 50 Ma: from 14‰ to 2‰ in the northwest Pacific (ODP site 1209), from 12‰ to 4‰ in the southeast Atlantic (ODP site 1263), and from 9‰ to 4‰ in the northwest Atlantic (IODP site U1409). This foraminifera-bound δ15N change is on par, if not greater, than the largest changes that have been observed in bulk sediment δ15N over the last 600 million years. The shared change among the sites implies a change in mean δ15N of oceanic fixed N, which is thought to be sensitive to the ratio of water column to sedimentary denitrification, with a higher δ15N reflecting a greater proportion of denitrification occurring in the water column. Today, water column denitrification occurs in the shallow subsurface, in regions where these waters are suboxic. Thus, the δ15N decrease may reflect a slowing of water column denitrification, which can be generated by a decline in shallow subsurface suboxia. A key factor in the extent of shallow subsurface suboxia is the amount of "preformed oxygen," the initial concentration of dissolved O2 in the water that flows from the surface into the shallow subsurface: a decline in suboxia would require a rise in preformed oxygen from 56 to 50 Ma. The δ15N decline occurs before the onset of cooling in the Eocene, eliminating global temperature change as the driver of increased preformed oxygen. Instead we favor explanations that involve tectonically driven changes in continental configuration and shallow and mid-depth ocean bathymetry. Indeed, the δ15N decline appears coincident with the initiation of bathymetric effects from the collision of India with Asia. This category of explanation is consistent with the overlap of the δ15N decline with the previously identified increase in marine barite δ34S at 51 Ma.

Geophysical Investigations at Hidden Dam, Raymond, California: Summary of Fieldwork and Data Analysis

USGS Publications Warehouse

Minsley, Burke J.; Burton, Bethany L.; Ikard, Scott; Powers, Michael H.

2010-01-01

Geophysical field investigations have been carried out at the Hidden Dam in Raymond, California for the purpose of better understanding the hydrogeology and seepage-related conditions at the site. Known seepage areas on the northwest right abutment area of the downstream side of the dam are documented by Cedergren. Subsequent to the 1980 seepage study, a drainage blanket with a subdrain system was installed to mitigate downstream seepage. Flow net analysis provided by Cedergren suggests that the primary seepage mechanism involves flow through the dam foundation due to normal reservoir pool elevations, which results in upflow that intersects the ground surface in several areas on the downstream side of the dam. In addition to the reservoir pool elevations and downstream surface topography, flow is also controlled by the existing foundation geology as well as the presence or absence of a horizontal drain within the downstream portion of the dam. The purpose of the current geophysical work is to (1) identify present-day seepage areas that may not be evident due to the effectiveness of the drainage blanket in redirecting seepage water, and (2) provide information about subsurface geologic structures that may control subsurface flow and seepage. These tasks are accomplished through the use of two complementary electrical geophysical methods, self-potentials (SP) and direct-current (DC) electrical resistivity, which have been commonly utilized in dam-seepage studies. SP is a passive method that is primarily sensitive to active subsurface groundwater flow and seepage, whereas DC resistivity is an active-source method that is sensitive to changes in subsurface lithology and groundwater saturation. The focus of this field campaign was on the downstream area on the right abutment, or northwest side of the dam, as this is the main area of interest regarding seepage. Two exploratory self-potential lines were also collected on the downstream left abutment of the dam to identify potential seepage in that area. This report is primarily a summary of the field geophysical data acquisition, with some preliminary results and interpretation. Further work will involve a more rigorous analysis of the geophysical datasets and an examination of a large dataset of historical observations of water levels in a number of observation wells and piezometers compared with reservoir elevation. In addition, a partially saturated flow model will be developed to better understand seepage patterns given the available information about dam construction, geophysical results, and data from installed observation wells and piezometers.

The Effect of Projectile Density and Disruption on the Crater Excavation Flow-Field

NASA Technical Reports Server (NTRS)

Anderson, Jennifer L. B.; Schultz, P. H.

2005-01-01

The ejection parameters of material excavated by a growing crater directly relate to the subsurface excavation flow-field. The ejection angles and speeds define the end of subsurface material streamlines at the target surface. Differences in the subsurface flow-fields can be inferred by comparing observed ejection parameters of various impacts obtained using three-dimensional particle image velocimetry (3D PIV). The work presented here investigates the observed ejection speeds and angles of material ejected during vertical (90 impact angle) experimental impacts for a range of different projectile types. The subsurface flow-fields produced during vertical impacts are simple when compared with that of oblique impacts, affected primarily by the depth of the energy and momentum deposition of the projectile. This depth is highly controlled by the projectile/target density ratio and the disruption of the projectile (brittle vs. ductile deformation). Previous studies indicated that cratering efficiency and the crater diameter/depth ratio were affected by projectile disruption, velocity, and the projectile/target density ratio. The effect of these projectile properties on the excavation flow-field are examined by comparing different projectile materials.

Influences of bicarbonate on processes of enamel subsurface remineralization and demineralization: assessment using micro-Raman spectroscopy and transverse microradiography.

PubMed

Kuramochi, Erika; Iizuka, Junko; Mukai, Yoshiharu

2016-12-01

In the present study, we investigated, using micro-Raman spectroscopy (Raman) and transverse microradiography, the influence of bicarbonate [sodium hydrogen carbonate (NaHCO 3 )] on the effects of carbonate ions in the mineral phase during demineralization (acid resistance test) of subsurface lesions. Baseline lesions were created by demineralizing bovine enamel, and specimens were then exposed to remineralization solutions containing 0, 5, or 50 mM bicarbonate. Acid resistance tests were performed on remineralized and sound enamel specimens. Raman spectra showed that carbonate and phosphate were incorporated into both surface layers and lesion bodies during remineralization in the presence of bicarbonate. Moreover, the presence of bicarbonate did not affect the rates of remineralization, although the average mineral profiles of remineralized enamel differed from those of sound enamel after acid resistance tests. Raman analyses enabled close evaluation of site-specific characteristics of carbonate and phosphate in subsurface lesions. In conclusion, incorporation of carbonate and phosphate ions into enamel subsurface lesions during remineralization does not affect the magnitude of remineralization or acid resistance. © 2016 Eur J Oral Sci.

Conceptual Model Evaluation using Advanced Parameter Estimation Techniques with Heat as a Tracer

NASA Astrophysics Data System (ADS)

Naranjo, R. C.; Morway, E. D.; Healy, R. W.

2016-12-01

Temperature measurements made at multiple depths beneath the sediment-water interface has proven useful for estimating seepage rates from surface-water channels and corresponding subsurface flow direction. Commonly, parsimonious zonal representations of the subsurface structure are defined a priori by interpretation of temperature envelopes, slug tests or analysis of soil cores. However, combining multiple observations into a single zone may limit the inverse model solution and does not take full advantage of the information content within the measured data. Further, simulating the correct thermal gradient, flow paths, and transient behavior of solutes may be biased by inadequacies in the spatial description of subsurface hydraulic properties. The use of pilot points in PEST offers a more sophisticated approach to estimate the structure of subsurface heterogeneity. This presentation evaluates seepage estimation in a cross-sectional model of a trapezoidal canal with intermittent flow representing four typical sedimentary environments. The recent improvements in heat as a tracer measurement techniques (i.e. multi-depth temperature probe) along with use of modern calibration techniques (i.e., pilot points) provides opportunities for improved calibration of flow models, and, subsequently, improved model predictions.

Subsurface Ocean Tides in Enceladus and Other Icy Moons

NASA Astrophysics Data System (ADS)

Beuthe, M.

2016-12-01

Could tidal dissipation within Enceladus' subsurface ocean account for the observed heat flow? Earthlike models of dynamical tides give no definitive answer because they neglect the influence of the crust. I propose here the first model of dissipative tides in a subsurface ocean, by combining the Laplace Tidal Equations with the membrane approach. For the first time, it is possible to compute tidal dissipation rates within the crust, ocean, and mantle in one go. I show that oceanic dissipation is strongly reduced by the crustal constraint, and thus contributes little to Enceladus' present heat budget. Tidal resonances could have played a role in a forming or freezing ocean less than 100 meters deep. The model is general: it applies to all icy satellites with a thin crust and a shallow or stratified ocean. Scaling rules relate the resonances and dissipation rate of a subsurface ocean to the ones of a surface ocean. If the ocean has low viscosity, the westward obliquity tide does not move the crust. Therefore, crustal dissipation due to dynamical obliquity tides can differ from the static prediction by up to a factor of two.

Crystal Orientation Effect on the Subsurface Deformation of Monocrystalline Germanium in Nanometric Cutting.

PubMed

Lai, Min; Zhang, Xiaodong; Fang, Fengzhou

2017-12-01

Molecular dynamics simulations of nanometric cutting on monocrystalline germanium are conducted to investigate the subsurface deformation during and after nanometric cutting. The continuous random network model of amorphous germanium is established by molecular dynamics simulation, and its characteristic parameters are extracted to compare with those of the machined deformed layer. The coordination number distribution and radial distribution function (RDF) show that the machined surface presents the similar amorphous state. The anisotropic subsurface deformation is studied by nanometric cutting on the (010), (101), and (111) crystal planes of germanium, respectively. The deformed structures are prone to extend along the 110 slip system, which leads to the difference in the shape and thickness of the deformed layer on various directions and crystal planes. On machined surface, the greater thickness of subsurface deformed layer induces the greater surface recovery height. In order to get the critical thickness limit of deformed layer on machined surface of germanium, the optimized cutting direction on each crystal plane is suggested according to the relevance of the nanometric cutting to the nanoindentation.

Accelerated aging studies of UHMWPE. II. Virgin UHMWPE is not immune to oxidative degradation.

PubMed

Edidin, A A; Villarraga, M L; Herr, M P; Muth, J; Yau, S S; Kurtz, S M

2002-08-01

In Part I of this series, we showed that aging at elevated oxygen pressure is more successful at increasing the depth to which degradation occurs although it, too, generally causes greater degradation at the surface than at the subsurface. Therefore we hypothesized that thermal degradation alone, in the absence of free radicals, could be sufficient to artificially age UHMWPE in a manner analogous to natural aging. In the present study, virgin and air-irradiated UHMWPE (extruded GUR 1050 and compression-molded 1900) were aged up to 4 weeks at elevated oxygen pressure, and the mechanical behavior at the surface and subsurface was examined. All the materials were substantially degraded following 4 weeks of aging, but the spatial variations in the nonirradiated materials more closely mimicked the previously observed subsurface peak of degradation seen in naturally aged UHMWPE following irradiation in air. This aged material could provide a more realistic model for subsurface mechanical degradation, making it suitable for further mechanical testing in venues such as wear simulation. Copyright 2002 Wiley Periodicals, Inc.

Linking Chaotic Advection with Subsurface Biogeochemical Processes

NASA Astrophysics Data System (ADS)

Mays, D. C.; Freedman, V. L.; White, S. K.; Fang, Y.; Neupauer, R.

2017-12-01

This work investigates the extent to which groundwater flow kinematics drive subsurface biogeochemical processes. In terms of groundwater flow kinematics, we consider chaotic advection, whose essential ingredient is stretching and folding of plumes. Chaotic advection is appealing within the context of groundwater remediation because it has been shown to optimize plume spreading in the laminar flows characteristic of aquifers. In terms of subsurface biogeochemical processes, we consider an existing model for microbially-mediated reduction of relatively mobile uranium(VI) to relatively immobile uranium(IV) following injection of acetate into a floodplain aquifer beneath a former uranium mill in Rifle, Colorado. This model has been implemented in the reactive transport code eSTOMP, the massively parallel version of STOMP (Subsurface Transport Over Multiple Phases). This presentation will report preliminary numerical simulations in which the hydraulic boundary conditions in the eSTOMP model are manipulated to simulate chaotic advection resulting from engineered injection and extraction of water through a manifold of wells surrounding the plume of injected acetate. This approach provides an avenue to simulate the impact of chaotic advection within the existing framework of the eSTOMP code.

A comprehensive inventory of radiological and nonradiological contaminants in waste buried or projected to be buried in the subsurface disposal area of the INEL RWMC during the years 1984-2003, Volume 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-05-01

This is the third volume of this comprehensive report of the inventory of radiological and nonradiological contaminants in waste buried or projected to be buried in the subsurface disposal area of the Idaho National Engineering Laboratory. Appendix B contains a complete printout of contaminant inventory and other information from the CIDRA Database and is presented in volumes 2 and 3 of the report.

A Cloud Based Framework For Monitoring And Predicting Subsurface System Behaviour

NASA Astrophysics Data System (ADS)

Versteeg, R. J.; Rodzianko, A.; Johnson, D. V.; Soltanian, M. R.; Dwivedi, D.; Dafflon, B.; Tran, A. P.; Versteeg, O. J.

2015-12-01

Subsurface system behavior is driven and controlled by the interplay of physical, chemical, and biological processes which occur at multiple temporal and spatial scales. Capabilities to monitor, understand and predict this behavior in an effective and timely manner are needed for both scientific purposes and for effective subsurface system management. Such capabilities require three elements: Models, Data and an enabling cyberinfrastructure, which allow users to use these models and data in an effective manner. Under a DOE Office of Science funded STTR award Subsurface Insights and LBNL have designed and implemented a cloud based predictive assimilation framework (PAF) which automatically ingests, controls quality and stores heterogeneous physical and chemical subsurface data and processes these data using different inversion and modeling codes to provide information on the current state and evolution of subsurface systems. PAF is implemented as a modular cloud based software application with five components: (1) data acquisition, (2) data management, (3) data assimilation and processing, (4) visualization and result delivery and (5) orchestration. Serverside PAF uses ZF2 (a PHP web application framework) and Python and both open source (ODM2) and in house developed data models. Clientside PAF uses CSS and JS to allow for interactive data visualization and analysis. Client side modularity (which allows for a responsive interface) of the system is achieved by implementing each core capability of PAF (such as data visualization, user configuration and control, electrical geophysical monitoring and email/SMS alerts on data streams) as a SPA (Single Page Application). One of the recent enhancements is the full integration of a number of flow and mass transport and parameter estimation codes (e.g., MODFLOW, MT3DMS, PHT3D, TOUGH, PFLOTRAN) in this framework. This integration allows for autonomous and user controlled modeling of hydrological and geochemical processes. In our presentation we will discuss our software architecture and present the results of using these codes and the overall developed performance of our framework using hydrological, geochemical and geophysical data from the LBNL SFA2 Rifle field site.

The nature and function of microbial enzymes in subsurface marine sediments

NASA Astrophysics Data System (ADS)

Steen, A. D.; Schmidt, J.

2016-02-01

Isotopic and genomic evidence indicates that marine sediments contain populations of active heterotrophic microorganisms which appear to metabolize old, detrital, apparently recalcitrant organic matter. In surface communities, heterotrophs use extracellular enzymes to access complex organic matter. In subsurface sediments, in which microbial doubling times can be on the order of hundreds or thousands of years, it is not clear whether extracellular enzymes could remain stable and active long enough to constitute a 'profitable' stragtegy for accessing complex organic carbon. Here we present evidence that a wide range of extracellular enzyme are active in subsurface sediments from two different environments: the White Oak River, NC, and deep (up to 80 m) sediments of the Baltic Sea Basin recovered from IODP Expedition 347. In the White Oak River, enzymes from deeper sediments appear to be better-adapted to highly-degraded organic matter than enzymes from surface sediments. In the Baltic Sea, preliminary data suggest that enzymes related to nitrogen acquisition are preferentially expressed. By characterizing the extracellular enzymes present in marine sediments, we hope to achieve a better understanding of the mechanisms that control sedimentary organic matter remineralization and preservation.

Cu-rGO subsurface layer creation on copper substrate and its resistance to oxidation

NASA Astrophysics Data System (ADS)

Pietrzak, Katarzyna; Strojny-Nędza, Agata; Olesińska, Wiesława; Bańkowska, Anna; Gładki, Andrzej

2017-11-01

On the basis of a specially designed experiment, this paper presents a model, which is an attempt to explain the mechanism of formatting and creating oxidation resistance of Cu-rGO subsurface layers. Practically zero chemical affinity of copper to carbon is a fundamental difficulty in creating composite structures of Cu-C, properties which are theoretically possible to estimate. In order to bind the thermally reduced graphene oxide with copper surface, the effect of structural rebuilding of the copper oxide, in the process of annealing in a nitrogen atmosphere, have been used. On intentionally oxidized and anoxic copper substrates the dispersed graphene oxide (GO) and thermally reduced graphene oxide (rGO) were loaded. Annealing processes after the binding effects of both graphene oxide forms to Cu substrates were tested. The methods for high-resolution electron microscopy were found subsurface rGO-Cu layer having a substantially greater resistance to oxidation than pure copper. The mechanism for the effective resistance to oxidation of the Cu-rGO has been presented in a hypothetical form.

Evaluation of nutrient removal efficiency and microbial enzyme activity in a baffled subsurface-flow constructed wetland system

Treesearch

Lihua Cui; Ying Ouyang; Wenjie Gu; Weozhi Yang; Qiaoling Xu

2013-01-01

In this study, the enzyme activities and their relationships to domestic wastewater purification are investigated in four different types of subsurface-flow constructed wetlands (CWs), namely the traditional horizontal subsurface-flow, horizontal baffled subsurface-flow, vertical baffled subsurface-flow, and composite baffled subsurface-flow CWs. Results showed that...

HYDROGEOLOGIC CASE STUDIES (DENVER PRESENTATION)

EPA Science Inventory

Hydrogeology is the foundation of subsurface site characterization for evaluations of monitored natural attenuation (MNA). Three case studies are presented. Examples of the potentially detrimental effects of drilling additives on ground-water samples from monitoring wells are d...

Subsurface And Surface Water Flow Interactions

EPA Science Inventory

In this chapter we present basic concepts and principles underlying the phenomena of groundwater and surface water interactions. Fundamental equations and analytical and numerical solutions describing stream-aquifer interactions are presented in hillslope and riparian aquifer en...

Geologic logs of geotechnical cores from the subsurface Sacramento-San Joaquin Delta, California

USGS Publications Warehouse

Maier, Katherine L.; Ponti, Daniel J.; Tinsley, John C.; Gatti, Emma; Pagenkopp, Mark

2014-01-01

This report presents and summarizes descriptive geologic logs of geotechnical cores collected from 2009–12 in the Sacramento–San Joaquin Delta, California, by the California Department of Water Resources. Graphic logs are presented for 1,785.7 ft of retained cores from 56 borehole sites throughout the Sacramento-San Joaquin Delta. Most core sections are from a depth of ~100–200 feet. Cores primarily contain mud, silt, and sand lithologies. Tephra (volcanic ash and pumice), paleosols, and gravels are also documented in some core sections. Geologic observations contained in the core logs in this report provide stratigraphic context for subsequent sampling and data for future chronostratigraphic subsurface correlations.

Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures

PubMed Central

Schmidt, Matthew W.; Chang, Ping; Hertzberg, Jennifer E.; Them, Theodore R.; Ji, Link; Otto-Bliesner, Bette L.

2012-01-01

Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and subthermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. Our results show significant changes in the vertical thermal gradient of the upper water column, with the warmest subsurface temperatures of the last deglacial transition corresponding to the onset of the Younger Dryas. Furthermore, we present new analyses of a climate model simulation forced with freshwater discharge into the North Atlantic under Last Glacial Maximum forcings and boundary conditions that reveal a maximum subsurface warming in the vicinity of the core site and a vertical thermal gradient change at the onset of AMOC weakening, consistent with the reconstructed record. Together, our proxy reconstructions and modeling results provide convincing evidence for a subsurface oceanic teleconnection linking high-latitude North Atlantic climate to the tropical Atlantic during periods of reduced AMOC across the last deglacial transition. PMID:22908256

Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures.

PubMed

Schmidt, Matthew W; Chang, Ping; Hertzberg, Jennifer E; Them, Theodore R; Ji, Link; J, Link; Otto-Bliesner, Bette L

2012-09-04

Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and subthermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. Our results show significant changes in the vertical thermal gradient of the upper water column, with the warmest subsurface temperatures of the last deglacial transition corresponding to the onset of the Younger Dryas. Furthermore, we present new analyses of a climate model simulation forced with freshwater discharge into the North Atlantic under Last Glacial Maximum forcings and boundary conditions that reveal a maximum subsurface warming in the vicinity of the core site and a vertical thermal gradient change at the onset of AMOC weakening, consistent with the reconstructed record. Together, our proxy reconstructions and modeling results provide convincing evidence for a subsurface oceanic teleconnection linking high-latitude North Atlantic climate to the tropical Atlantic during periods of reduced AMOC across the last deglacial transition.

Seasonal dynamics in colored dissolved organic matter in the Mediterranean Sea: Patterns and drivers

NASA Astrophysics Data System (ADS)

Xing, Xiaogang; Claustre, Hervé; Wang, Haili; Poteau, Antoine; D`Ortenzio, Fabrizio

2014-01-01

Two autonomous profiling “Bio-Argo” floats were deployed in the northwestern and eastern sub-basins of the Mediterranean Sea in 2008. They recorded at high vertical (1 m) and temporal (5 day) resolution, the vertical distribution and seasonal variation of colored dissolved organic matter (CDOM), as well as of chlorophyll-a concentration and hydrological variables. The CDOM standing stock presented a clear seasonal dynamics with the progressive summer formation and winter destruction of subsurface CDOM maxima (YSM, for Yellow Substance Maximum). It was argued that subsurface CDOM is a by-product of phytoplankton, based on two main characteristics, (1) the YSM was located at the same depth than the deep chlorophyll maximum (DCM) and (2) the CDOM increased in summer parallels the decline in chlorophyll-a. These observations suggested an indirect but tight coupling between subsurface CDOM and phytoplankton via microbial activity or planktonic foodweb interactions. Moreover, the surface CDOM variations observed both by floats and MODIS displayed different seasonal dynamics from what recorded at subsurface one. This implies that CDOM standing stock can be hardly detected by satellite. It is worthnoting that surface CDOM was found to be more related to the sea surface temperature (SST) than chlorophyll-a concentration, suggesting its physical origin, in contrast to the biological origin of YSM and subsurface standing stocks.

Studying Phobos subsurface structure elementary composition by neutron and gamma-rays spectrometers "NS HEND" from "Phobos-Grunt" mission.

NASA Astrophysics Data System (ADS)

Kozyrev, S. Alexander; Litvak, Maxim; Malakhov, Alexey; Mokrousov, Maxim; Mitrofanov, Igor; Sanin, Anton; Schulz, Rita; Shvetsov, Valery; Rogozhin, Alexander; Timoshenko, Genagy; Tretyakov, Vladislav; Vostrukhin, Andrey

The Neutron Spectrometer HEND (NS HEND) has been proposed for studying elemental com-position of Phobos (the Mars's moon) regolith by "Phobos-Grunt" mission. NS HEND have been selected by the Federal Space Agency of Russia for the Lander of the "Phobos-Grunt" mission scheduled for launch in 2011. The shallow subsurface of Phobos might be studied by observations of induced nuclear gamma-ray lines and neutron emission. Secondary gamma-rays and neutrons are produced by energetic Galactic Cosmic Rays within 1-2 meter layer of subsur-face. The knowledge of the spectral density of neutrons in addition to measurements of nuclear gamma lines allows to deconvolve concentrations of soil-constituting elements. That is why nuclear instruments include both the segment for detection of gamma ray lines and segment of neutron spectrometer for the measurement of the neutron leakage spectra. Moreover, mea-surements of neutrons at 2.2 MeV line will also allow to study the content of hydrogen within subsurface layer about 1 meter deep. This instrument, will be able to provide observational data for composition of Phobos regolith and content of natural radioactive elements K, U and Th, and also for content of hydrogen or water ice in the Phobos subsurface. At present, the flight units of NS HEND instrument is manufactured, tested and current go through physical calibration.

Direct thermal effects of the Hadean bombardment did not limit early subsurface habitability

NASA Astrophysics Data System (ADS)

Grimm, R. E.; Marchi, S.

2018-03-01

Intense bombardment is considered characteristic of the Hadean and early Archean eons, yet some detrital zircons indicate that near-surface water was present and thus at least intervals of clement conditions may have existed. We investigate the habitability of the top few kilometers of the subsurface by updating a prior approach to thermal evolution of the crust due to impact heating, using a revised bombardment history, a more accurate thermal model, and treatment of melt sheets from large projectiles (>100 km diameter). We find that subsurface habitable volume grows nearly continuously throughout the Hadean and early Archean (4.5-3.5 Ga) because impact heat is dissipated rapidly compared to the total duration and waning strength of the bombardment. Global sterilization was only achieved using an order of magnitude more projectiles in 1/10 the time. Melt sheets from large projectiles can completely resurface the Earth several times prior to ∼4.2 Ga but at most once since then. Even in the Hadean, melt sheets have little effect on habitability because cooling times are short compared to resurfacing intervals, allowing subsurface biospheres to be locally re-established by groundwater infiltration between major impacts. Therefore the subsurface is always habitable somewhere, and production of global steam or silicate-vapor atmospheres are the only remaining avenues to early surface sterilization by bombardment.

In-situ GPR test for three-dimensional mapping of the dielectric constant in a rock mass

NASA Astrophysics Data System (ADS)

Elkarmoty, Mohamed; Colla, Camilla; Gabrielli, Elena; Papeschi, Paolo; Bonduà, Stefano; Bruno, Roberto

2017-11-01

The Ground Penetrating Radar (GPR) is used to detect subsurface anomalies in several applications. The more the velocity of propagation or the dielectric constant is estimated accurately, the more the detection of anomalies at true subsurface depth can be accurately obtained. Since many GPR applications are performed in rock mass with non-homogeneous discontinuous nature, errors in estimating a bulk velocity of propagation or dielectric constant are possible. This paper presents a new in-situ GPR test for mapping the dielectric constant variability in a rock mass. The main aim is to investigate to what extent the dielectric constant is variable in the micro and macro scale of a typical rock mass and to give attention to GPR users in rock mass mediums. The methodology of this research is based on the insertion of steel rods in a rock mass, thus acting as reflectors. The velocity of propagation can be then modeled, from hyperbolic reflections, in the form of velocity pathways from antenna positions to a buried rod. Each pathway is characterized by discrete points which are assumed in three dimensions as centers of micro cubic rock mass. This allows converting the velocity of propagation into a dielectric constant for mapping and modeling the dielectric constant in a volumetric rock mass using a volumetric data visualization software program (Voxler). In a case study, 6 steel drilling rods were diagonally inserted in a vertical face of a bench in a sandstone quarry. Five equally spaced parallel lines, almost perpendicular to the orientations of the rods, were surveyed by a dual frequency GPR antenna of 200 and 600 MHz. The results show that the dielectric constant is randomly varied within the micro and macro scale either in single radargrams or in the volumetric rock mass. The proposed method can be useful if considered in signal processing software programs, particularly in presence of subsurface utilities with known geometry and dimension, allowing converting double travel time, through portions of a radargram, into more reliable depths using discrete dielectric constant values instead of one value for a whole radargram.

Modeling of Ureolytic Calcite Precipitation for the Remediation of Sr-90 Using a Variable Velocity Streamtube Ensemble

NASA Astrophysics Data System (ADS)

Weathers, T. S.; Ginn, T. R.; Spycher, N.; Barkouki, T. H.; Fujita, Y.; Smith, R. W.

2009-12-01

Subsurface contamination is often mitigated with an injection/extraction well system. An understanding of heterogeneities within this radial flowfield is critical for modeling, prediction, and remediation of the subsurface. We address this using a Lagrangian approach: instead of depicting spatial extents of solutes in the subsurface we focus on their arrival distribution at the control well(s). A well-to-well treatment system that incorporates in situ microbially-mediated ureolysis to induce calcite precipitation for the immobilization of strontium-90 has been explored at the Vadose Zone Research Park (VZRP) near Idaho Falls, Idaho. PHREEQC2 is utilized to model the kinetically-controlled ureolysis and consequent calcite precipitation. PHREEQC2 provides a one-dimensional advective-dispersive transport option that can be and has been used in streamtube ensemble models. Traditionally, each streamtube maintains uniform velocity; however in radial flow in homogeneous media, the velocity within any given streamtube is variable in space, being highest at the input and output wells and approaching a minimum at the midpoint between the wells. This idealized velocity variability is of significance if kinetic reactions are present with multiple components, if kinetic reaction rates vary in space, if the reactions involve multiple phases (e.g. heterogeneous reactions), and/or if they impact physical characteristics (porosity/permeability), as does ureolytically driven calcite precipitation. Streamtube velocity patterns for any particular configuration of injection and withdrawal wells are available as explicit calculations from potential theory, and also from particle tracking programs. To approximate the actual spatial distribution of velocity along streamtubes, we assume idealized non-uniform velocity associated with homogeneous media. This is implemented in PHREEQC2 via a non-uniform spatial discretization within each streamtube that honors both the streamtube’s travel time and the idealized “fast-slow-fast” nonuniform velocity along the streamline. Breakthrough curves produced by each simulation are weighted by the path-respective flux fractions (obtained by deconvolution of tracer tests conducted at the VZRP) to obtain the flux-average of flow contributions to the observation well. Breakthrough data from urea injection experiments performed at the VZRP are compared to the model results from the PHREEQC2 variable velocity ensemble.

A comparison between modeled and measured permafrost temperatures at Ritigraben borehole, Switzerland

NASA Astrophysics Data System (ADS)

Mitterer-Hoinkes, Susanna; Lehning, Michael; Phillips, Marcia; Sailer, Rudolf

2013-04-01

The area-wide distribution of permafrost is sparsely known in mountainous terrain (e.g. Alps). Permafrost monitoring can only be based on point or small scale measurements such as boreholes, active rock glaciers, BTS measurements or geophysical measurements. To get a better understanding of permafrost distribution, it is necessary to focus on modeling permafrost temperatures and permafrost distribution patterns. A lot of effort on these topics has been already expended using different kinds of models. In this study, the evolution of subsurface temperatures over successive years has been modeled at the location Ritigraben borehole (Mattertal, Switzerland) by using the one-dimensional snow cover model SNOWPACK. The model needs meteorological input and in our case information on subsurface properties. We used meteorological input variables of the automatic weather station Ritigraben (2630 m) in combination with the automatic weather station Saas Seetal (2480 m). Meteorological data between 2006 and 2011 on an hourly basis were used to drive the model. As former studies showed, the snow amount and the snow cover duration have a great influence on the thermal regime. Low snow heights allow for deeper penetration of low winter temperatures into the ground, strong winters with a high amount of snow attenuate this effect. In addition, variations in subsurface conditions highly influence the temperature regime. Therefore, we conducted sensitivity runs by defining a series of different subsurface properties. The modeled subsurface temperature profiles of Ritigraben were then compared to the measured temperatures in the Ritigraben borehole. This allows a validation of the influence of subsurface properties on the temperature regime. As expected, the influence of the snow cover is stronger than the influence of sub-surface material properties, which are significant, however. The validation presented here serves to prepare a larger spatial simulation with the complex hydro-meteorological 3-dimensional model Alpine 3D, which is based on a distributed application of SNOWPACK.

Concentration and characterization of dissolved organic matter in the surface microlayer and subsurface water of the Bohai Sea, China

NASA Astrophysics Data System (ADS)

Chen, Yan; Yang, Gui-Peng; Wu, Guan-Wei; Gao, Xian-Chi; Xia, Qing-Yan

2013-01-01

A total of 19 sea-surface microlayer and corresponding subsurface samples collected from the Bohai Sea, China in April 2010 were analyzed for chlorophyll a, dissolved organic carbon (DOC) and its major compound classes including total dissolved carbohydrates (TDCHO, including monosaccharides, MCHO, and polysaccharides, PCHO) and total hydrolysable amino acids (THAA, including dissolved free, DFAA, and combined fraction, DCAA). The concentrations of DOC in the subsurface water ranged from 130.2 to 407.7 μM C, with an average of 225.9±75.4 μM C, while those in the surface microlayer varied between 140.1 and 330.9 μM C, with an average of 217.8±56.8 μM C. The concentrations of chlorophyll a, DOC, TDCHO and THAA in the microlayer were, respectively correlated with their subsurface water concentrations, implying that there was a strong exchange effect between the microlayer and subsurface water. The concentrations of DOC and TDCHO were negatively correlated with salinity, respectively, indicating that water mixing might play an important role in controlling the distribution of DOC and TDCHO in the water column. Major constituents of DCAA and DFAA present in the study area were glycine, alanine, glutamic acid, serine and histidine. Principal component analysis (PCA) was applied to examine the complex compositional differences that existed among the sampling sites. Our results showed that DFAA had higher mole percentages of glycine, valine and serine in the microlayer than in the subsurface water, while DCAA tended to have higher mole percentages of glutamic acid, aspartic acid, threonine, arginine, alanine, tyrosine, phenylalanine and leucine in the microlayer. The yields of TDCHO and THAA exhibited similar trends between the microlayer and subsurface water. Carbohydrate species displayed significant enrichment in the microlayer, whereas the DFAA and DCAA exhibited non-uniform enrichment in the microlayer.

Subsurface Implications of Spatially Variable Seafloor Character on the Atlantis Massif

NASA Astrophysics Data System (ADS)

Greene, J. A.; Tominaga, M.; Blackman, D. K.

2014-12-01

We documented and mapped the characteristics of the seafloor on the Atlantis Massif, an ocean core complex located at 30°N on the Mid-Atlantic Ridge. Our goal is to investigate the implications of these surficial features, particularly whether their spatial variations might reflect subsurface lithology and geological processes. We utilized data collected during the MARVEL 2000 cruise AT3-60, specifically Alvin videos and rock samples, Argo II digital still photos, and TOBI/DSL-120 side-scan sonar mosaic. The Alvin dives studied occurred over the Central Dome and Eastern Block, which is interpreted as the hanging wall to the detachment that unroofed the dome. We also studied two Argo II dives located over the Central Dome, one over the Eastern Block, and one over the Western Shoulder of the southern dome. The TOBI/DSL-120 side-scan sonar followed a widespread, looped track providing near total coverage of the massif. We classified the character of the seafloor based on imagery, the acoustic reflectivity, and the basic composition of rock samples. To aid in our classification, we merged Argo II still images to produce photo-mosaics displaying tens of meters long transects. We then classified the seafloor as unconsolidated sediment, lithified sediment (a carbonate crust or cap), exposed bedrock, or rubble. To obtain a broader understanding of the Atlantis Massif, we analyzed the distribution of these classes of seafloor. Over the Central Dome and Western Shoulder, we found most seafloor classes present in notable amounts, with many individual areas dominated by a particular type.

Hydrogeophysical investigations at Hidden Dam, Raymond, California

USGS Publications Warehouse

Minsley, Burke J.; Burton, Bethany L.; Ikard, Scott; Powers, Michael H.

2011-01-01

Self-potential and direct current resistivity surveys are carried out at the Hidden Dam site in Raymond, California to assess present-day seepage patterns and better understand the hydrogeologic mechanisms that likely influence seepage. Numerical modeling is utilized in conjunction with the geophysical measurements to predict variably-saturated flow through typical two-dimensional dam cross-sections as a function of reservoir elevation. Several different flow scenarios are investigated based on the known hydrogeology, as well as information about typical subsurface structures gained from the resistivity survey. The flow models are also used to simulate the bulk electrical resistivity in the subsurface under varying saturation conditions, as well as the self-potential response using petrophysical relationships and electrokinetic coupling equations.The self-potential survey consists of 512 measurements on the downstream area of the dam, and corroborates known seepage areas on the northwest side of the dam. Two direct-current resistivity profiles, each approximately 2,500 ft (762 m) long, indicate a broad sediment channel under the northwest side of the dam, which may be a significant seepage pathway through the foundation. A focusing of seepage in low-topography areas downstream of the dam is confirmed from the numerical flow simulations, which is also consistent with past observations. Little evidence of seepage is identified from the self-potential data on the southeast side of the dam, also consistent with historical records, though one possible area of focused seepage is identified near the outlet works. Integration of the geophysical surveys, numerical modeling, and observation well data provides a framework for better understanding seepage at the site through a combined hydrogeophysical approach.

Revealing the unexplored fungal communities in deep groundwater of crystalline bedrock fracture zones in Olkiluoto, Finland.

PubMed

Sohlberg, Elina; Bomberg, Malin; Miettinen, Hanna; Nyyssönen, Mari; Salavirta, Heikki; Vikman, Minna; Itävaara, Merja

2015-01-01

The diversity and functional role of fungi, one of the ecologically most important groups of eukaryotic microorganisms, remains largely unknown in deep biosphere environments. In this study we investigated fungal communities in packer-isolated bedrock fractures in Olkiluoto, Finland at depths ranging from 296 to 798 m below surface level. DNA- and cDNA-based high-throughput amplicon sequencing analysis of the fungal internal transcribed spacer (ITS) gene markers was used to examine the total fungal diversity and to identify the active members in deep fracture zones at different depths. Results showed that fungi were present in fracture zones at all depths and fungal diversity was higher than expected. Most of the observed fungal sequences belonged to the phylum Ascomycota. Phyla Basidiomycota and Chytridiomycota were only represented as a minor part of the fungal community. Dominating fungal classes in the deep bedrock aquifers were Sordariomycetes, Eurotiomycetes, and Dothideomycetes from the Ascomycota phylum and classes Microbotryomycetes and Tremellomycetes from the Basidiomycota phylum, which are the most frequently detected fungal taxa reported also from deep sea environments. In addition some fungal sequences represented potentially novel fungal species. Active fungi were detected in most of the fracture zones, which proves that fungi are able to maintain cellular activity in these oligotrophic conditions. Possible roles of fungi and their origin in deep bedrock groundwater can only be speculated in the light of current knowledge but some species may be specifically adapted to deep subsurface environment and may play important roles in the utilization and recycling of nutrients and thus sustaining the deep subsurface microbial community.

Image-guided ex-vivo targeting accuracy using a laparoscopic tissue localization system

NASA Astrophysics Data System (ADS)

Bieszczad, Jerry; Friets, Eric; Knaus, Darin; Rauth, Thomas; Herline, Alan; Miga, Michael; Galloway, Robert; Kynor, David

2007-03-01

In image-guided surgery, discrete fiducials are used to determine a spatial registration between the location of surgical tools in the operating theater and the location of targeted subsurface lesions and critical anatomic features depicted in preoperative tomographic image data. However, the lack of readily localized anatomic landmarks has greatly hindered the use of image-guided surgery in minimally invasive abdominal procedures. To address these needs, we have previously described a laser-based system for localization of internal surface anatomy using conventional laparoscopes. During a procedure, this system generates a digitized, three-dimensional representation of visible anatomic surfaces in the abdominal cavity. This paper presents the results of an experiment utilizing an ex-vivo bovine liver to assess subsurface targeting accuracy achieved using our system. During the experiment, several radiopaque targets were inserted into the liver parenchyma. The location of each target was recorded using an optically-tracked insertion probe. The liver surface was digitized using our system, and registered with the liver surface extracted from post-procedure CT images. This surface-based registration was then used to transform the position of the inserted targets into the CT image volume. The target registration error (TRE) achieved using our surface-based registration (given a suitable registration algorithm initialization) was 2.4 mm +/- 1.0 mm. A comparable TRE (2.6 mm +/- 1.7 mm) was obtained using a registration based on traditional fiducial markers placed on the surface of the same liver. These results indicate the potential of fiducial-free, surface-to-surface registration for image-guided lesion targeting in minimally invasive abdominal surgery.

Development of concepts for the management of thermal resources in urban areas - Assessment of transferability from the Basel (Switzerland) and Zaragoza (Spain) case studies

NASA Astrophysics Data System (ADS)

Epting, Jannis; García-Gil, Alejandro; Huggenberger, Peter; Vázquez-Suñe, Enric; Mueller, Matthias H.

2017-05-01

The shallow subsurface in urban areas is increasingly used by shallow geothermal energy systems as a renewable energy resource and as a cheap cooling medium, e.g. for building air conditioning. In combination with further anthropogenic activities, this results in altered thermal regimes in the subsurface and the so-called subsurface urban heat island effect. Successful thermal management of urban groundwater resources requires understanding the relative contributions of the different thermal parameters and boundary conditions that result in the "present thermal state" of individual urban groundwater bodies. To evaluate the "present thermal state" of urban groundwater bodies, good quality data are required to characterize the hydraulic and thermal aquifer parameters. This process also involved adequate monitoring systems which provide consistent subsurface temperature measurements and are the basis for parameterizing numerical heat-transport models. This study is based on previous work already published for two urban groundwater bodies in Basel (CH) and Zaragoza (ES), where comprehensive monitoring networks (hydraulics and temperature) as well as calibrated high-resolution numerical flow- and heat-transport models have been analyzed. The "present thermal state" and how it developed according to the different hydraulic and thermal boundary conditions is compared to a "potential natural state" in order to assess the anthropogenic thermal changes that have already occurred in the urban groundwater bodies we investigated. This comparison allows us to describe the various processes concerning groundwater flow and thermal regimes for the different urban settings. Furthermore, the results facilitate defining goals for specific aquifer regions, including future aquifer use and urbanization, as well as evaluating the thermal use potential for these regions. As one example for a more sustainable thermal use of subsurface water resources, we introduce the thermal management concept of the "relaxation factor", which is a first approach to overcome the present policy of "first come, first served". Remediation measures to regenerate overheated urban aquifers are also introduced. The transferability of the applied methods to other urban areas is discussed. It is shown that an appropriate selection of locations for monitoring hydraulic and thermal boundary conditions make it possible to implement representative interpretations of groundwater flow and thermal regimes as well as to set up high-resolution numerical flow- and heat-transport models. Those models are the basis for the sustainable management of thermal resources.

Subsurface agricultural irrigation drainage: the need for regulation.

PubMed

Lemly, A D

1993-04-01

Subsurface drainage resulting from irrigated agriculture is a toxic threat to fish and wildlife resources throughout the western United States. Studies by the U.S. Department of the Interior show that migratory waterfowl have been poisoned by drainwater contaminants on at least six national wildlife refuges. Allowing this poisoning to continue is a violation of the Migratory Bird Treaty Act under U.S. Federal law. Critical wetlands and waterfowl populations are threatened in both the Pacific and Central flyways. The public is also at risk and health warnings have been issued in some locations. Subsurface irrigation drainage is a complex effluent containing toxic concentrations of trace elements, salts, and nitrogenous compounds. Some of the contaminants are classified by the U.S. Environmental Protection Agency (EPA) as priority pollutants and they can be present in concentrations that exceed EPA's criteria for toxic waste. The on-farm drainage systems used to collect and transport this wastewater provide point-source identification as well as a mechanism for toxics control through the National Pollutant Discharge Elimination System (NPDES) permit process. A four-step approach is presented for dealing with irrigation drainage in an environmentally sound manner. This regulatory strategy is very similar to those commonly used for industrial discharges and includes site evaluation, contaminant reduction through NPDES, and compliance monitoring. The EPA must recognize subsurface irrigation drainage as a specific class of pollution subject to regulation under the NPDES process. Active involvement by EPA is necessary to ensure that adequate controls on this wastewater are implemented.

Single-cell genomics reveal metabolic strategies for microbial growth and survival in an oligotrophic aquifer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilkins, Michael J.; Kennedy, David W.; Castelle, Cindy

Bacteria from the genus Pedobacter are a major component of microbial assemblages at Hanford Site and have been shown to significantly change in abundance in response to the subsurface intrusion of Columbia River water. Here we employed single cell genomics techniques to shed light on the physiological niche of these microorganisms. Analysis of four Pedobacter single amplified genomes (SAGs) from Hanford Site sediments revealed a chemoheterotrophic lifestyle, with the potential to exist under both aerobic and microaerophilic conditions via expression of both aa 3­-type and cbb 3-type cytochrome c oxidases. These SAGs encoded a wide-range of both intra-and extra­-cellular carbohydrate-activemore » enzymes, potentially enabling the degradation of recalcitrant substrates such as xylan and chitin, and the utilization of more labile sugars such as mannose and fucose. Coupled to these enzymes, a diversity of transporters and sugar-binding molecules were involved in the uptake of carbon from the extracellular local environment. The SAGs were enriched in TonB-dependent receptors (TBDRs), which play a key role in uptake of substrates resulting from degradation of recalcitrant carbon. CRISPR-Cas mechanisms for resisting viral infections were identified in all SAGs. These data demonstrate the potential mechanisms utilized for persistence by heterotrophic microorganisms in a carbon-limited aquifer, and hint at potential linkages between observed Pedobacter abundance shifts within the 300 Area subsurface and biogeochemical shifts associated with Columbia River water intrusion.« less

HPC enabled real-time remote processing of laparoscopic surgery

NASA Astrophysics Data System (ADS)

Ronaghi, Zahra; Sapra, Karan; Izard, Ryan; Duffy, Edward; Smith, Melissa C.; Wang, Kuang-Ching; Kwartowitz, David M.

2016-03-01

Laparoscopic surgery is a minimally invasive surgical technique. The benefit of small incisions has a disadvantage of limited visualization of subsurface tissues. Image-guided surgery (IGS) uses pre-operative and intra-operative images to map subsurface structures. One particular laparoscopic system is the daVinci-si robotic surgical system. The video streams generate approximately 360 megabytes of data per second. Real-time processing this large stream of data on a bedside PC, single or dual node setup, has become challenging and a high-performance computing (HPC) environment may not always be available at the point of care. To process this data on remote HPC clusters at the typical 30 frames per second rate, it is required that each 11.9 MB video frame be processed by a server and returned within 1/30th of a second. We have implement and compared performance of compression, segmentation and registration algorithms on Clemson's Palmetto supercomputer using dual NVIDIA K40 GPUs per node. Our computing framework will also enable reliability using replication of computation. We will securely transfer the files to remote HPC clusters utilizing an OpenFlow-based network service, Steroid OpenFlow Service (SOS) that can increase performance of large data transfers over long-distance and high bandwidth networks. As a result, utilizing high-speed OpenFlow- based network to access computing clusters with GPUs will improve surgical procedures by providing real-time medical image processing and laparoscopic data.

Dual passivation of intrinsic defects at the compound semiconductor/oxide interface using an oxidant and a reductant.

PubMed

Kent, Tyler; Chagarov, Evgeniy; Edmonds, Mary; Droopad, Ravi; Kummel, Andrew C

2015-05-26

Studies have shown that metal oxide semiconductor field-effect transistors fabricated utilizing compound semiconductors as the channel are limited in their electrical performance. This is attributed to imperfections at the semiconductor/oxide interface which cause electronic trap states, resulting in inefficient modulation of the Fermi level. The physical origin of these states is still debated mainly because of the difficulty in assigning a particular electronic state to a specific physical defect. To gain insight into the exact source of the electronic trap states, density functional theory was employed to model the intrinsic physical defects on the InGaAs (2 × 4) surface and to model the effective passivation of these defects by utilizing both an oxidant and a reductant to eliminate metallic bonds and dangling-bond-induced strain at the interface. Scanning tunneling microscopy and spectroscopy were employed to experimentally determine the physical and electronic defects and to verify the effectiveness of dual passivation with an oxidant and a reductant. While subsurface chemisorption of oxidants on compound semiconductor substrates can be detrimental, it has been shown theoretically and experimentally that oxidants are critical to removing metallic defects at oxide/compound semiconductor interfaces present in nanoscale channels, oxides, and other nanostructures.

CHARACTERIZING SITE HYDROLOGY (WORKSHOP MSA PRESENTATION)

EPA Science Inventory

Hydrogeology is the foundation of subsurface site characterization for evaluations of monitored natural attenuation (MNA). Three case studies are presented. Examples of the potentially detrimental effects of drilling additives on ground-water samples from monitoring wells are d...

HYDROGEOLOGIC CASE STUDIE(PRESENTATION FOR MNA WORKSHOP)

EPA Science Inventory

Hydrogeology is the foundation of subsurface site characterization for evaluations of monitored natural attenuation (MNA). Three case studies are presented. Examples of the potentially detrimental effects of drilling additives on ground-water samples from monitoring wells are d...

A Study for Anisotropic Wavefield Analysis with Elastic Layered Models

NASA Astrophysics Data System (ADS)

Yoneki, R.; Mikada, H.; Takekawa, J.

2015-12-01

Subsurface materials are generally anisotropic due to complicated geological conditions, for example, sedimentary materials, fractures reflecting various stress conditions in the past and present in the subsurface. There are many studies on seismic wave propagation in TI (transversely isotropic) and orthorhombic media (e.g., Thomsen, 1986; Alkhalifah, 2000; Bansal and Sen, 2008). In most of those studies, the magnitude of anisotropy is assumed to be weak. Therefore, it may be not appropriate to apply their theories directly to strongly anisotropic subsurface media in seismic exploration. It is necessary to understand the effects of the anisotropy on the behavior of seismic wave propagation in strongly anisotropic media in the seismic exploration. In this study, we investigate the influence of strong anisotropy on received seismic waveforms using three-dimensional numerical models, and verified capability of detecting subsurface anisotropy. Our numerical models contain an isotropic and an anisotropic (VTI, transversely isotropic media with vertical symmetry axis) layer, respectively, in the isotropic background subsurface. Since the difference between the two models is only the anisotropy in the vertical propagation velocity, we could look at the influence of anisotropy in the residual wavefield that is the difference in the observed wavefields of two models. We analyzed the orbital motions of the residual wavefield to see what kind of wave motions the waveforms show. We found that the residual waveforms generated by the anisotropic layer include the orbital motions of shear waves right after the first arrival, i.e., mode conversion from the compressional waves due to the anisotropy. The residual waveforms could be exploited to estimate both the order of anisotropy and the thickness of anisotropic layer in subsurface.

Image-based overlay measurement using subsurface ultrasonic resonance force microscopy

NASA Astrophysics Data System (ADS)

Tamer, M. S.; van der Lans, M. J.; Sadeghian, H.

2018-03-01

Image Based Overlay (IBO) measurement is one of the most common techniques used in Integrated Circuit (IC) manufacturing to extract the overlay error values. The overlay error is measured using dedicated overlay targets which are optimized to increase the accuracy and the resolution, but these features are much larger than the IC feature size. IBO measurements are realized on the dedicated targets instead of product features, because the current overlay metrology solutions, mainly based on optics, cannot provide sufficient resolution on product features. However, considering the fact that the overlay error tolerance is approaching 2 nm, the overlay error measurement on product features becomes a need for the industry. For sub-nanometer resolution metrology, Scanning Probe Microscopy (SPM) is widely used, though at the cost of very low throughput. The semiconductor industry is interested in non-destructive imaging of buried structures under one or more layers for the application of overlay and wafer alignment, specifically through optically opaque media. Recently an SPM technique has been developed for imaging subsurface features which can be potentially considered as a solution for overlay metrology. In this paper we present the use of Subsurface Ultrasonic Resonance Force Microscopy (SSURFM) used for IBO measurement. We used SSURFM for imaging the most commonly used overlay targets on a silicon substrate and photoresist. As a proof of concept we have imaged surface and subsurface structures simultaneously. The surface and subsurface features of the overlay targets are fabricated with programmed overlay errors of +/-40 nm, +/-20 nm, and 0 nm. The top layer thickness changes between 30 nm and 80 nm. Using SSURFM the surface and subsurface features were successfully imaged and the overlay errors were extracted, via a rudimentary image processing algorithm. The measurement results are in agreement with the nominal values of the programmed overlay errors.

Bridging the Gap Between Understanding and Doing in Structural Geology - Coring the Subsurface with Scratch-Art

NASA Astrophysics Data System (ADS)

Bilsley, N. A.; Cook, H. M.

2016-12-01

Although most geology students feel the joy of interpreting geologic cross sections, few experience the challenges career geologists face in order to create these visual representations. Without a hefty budget and a drill rig, students generally miss out on the challenge of extrapolating subsurficial features from limited datasets, and jump to narrating geologic time through beautifully pre-drawn cross sections. Although this method allows students to practice relative dating techniques, they miss the practical step of learning how we have come to understand what the subsurface looks like in the first place. This activity was designed to close that gap, while giving students the opportunity to engage in peer learning by strategizing in groups, critiquing each other's work, and evaluating their own work. Broken into groups, students are instructed to create a geologic cross section that must include specific structural features. The cross sections are traded with another group, who reviews and provides feedback on the drawing before returning it back to the original group. The feedback is reviewed and incorporated, before the cross sections are colored and covered with black coated, clear scratch-art paper. The hidden cross sections are traded with a new group, who must decide where and how deep to scratch, or "core", on their cross section. Utilizing the data obtained from the cores, the students interpret and draw a new cross section. Finally, the scratch-art paper is removed, and the original cross section revealed. The differences between the original and interpreted subsurface as well as evaluation of sampling methods (e.g. location and depth of cores) are discussed within the groups and with the class. This activity bridges the gap between developing the intuition needed to create cross sections with realistic geoscientific techniques and utilizing cross sections to understand geologic time. In addition, not only does the activity require few supplies and minimal time of the instructor, but its peer-based learning approach stimulates creativity, allows students to effectively generate and communicate constructive feedback, and encourages students to evaluate and critique their methods and assumptions.

Application of near-surface geophysics as part of a hydrologic study of a subsurface drip irrigation system along the Powder River floodplain near Arvada, Wyoming

USGS Publications Warehouse

Sams, James I.; Veloski, Garret; Smith, Bruce D.; Minsley, Burke J.; Engle, Mark A.; Lipinski, Brian A.; Hammack, Richard W.; Zupancic, John W.

2014-01-01

Rapid development of coalbed natural gas (CBNG) production in the Powder River Basin (PRB) of Wyoming has occurred since 1997. National attention related to CBNG development has focused on produced water management, which is the single largest cost for on-shore domestic producers. Low-cost treatment technologies allow operators to reduce their disposal costs, provide treated water for beneficial use, and stimulate oil and gas production by small operators. Subsurface drip irrigation (SDI) systems are one potential treatment option that allows for increased CBNG production by providing a beneficial use for the produced water in farmland irrigation.Water management practices in the development of CBNG in Wyoming have been aided by integrated geophysical, geochemical, and hydrologic studies of both the disposal and utilization of water. The U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) and the U.S. Geological Survey (USGS) have utilized multi-frequency airborne, ground, and borehole electromagnetic (EM) and ground resistivity methods to characterize the near-surface hydrogeology in areas of produced water disposal. These surveys provide near-surface EM data that can be compared with results of previous surveys to monitor changes in soils and local hydrology over time as the produced water is discharged through SDI.The focus of this investigation is the Headgate Draw SDI site, situated adjacent to the Powder River near the confluence of a major tributary, Crazy Woman Creek, in Johnson County, Wyoming. The SDI system was installed during the summer of 2008 and began operation in October of 2008. Ground, borehole, and helicopter electromagnetic (HEM) conductivity surveys were conducted at the site prior to the installation of the SDI system. After the installation of the subsurface drip irrigation system, ground EM surveys have been performed quarterly (weather permitting). The geophysical surveys map the heterogeneity of the near-surface geology and hydrology of the study area. The geophysical data are consistent between surveys using different techniques and between surveys carried out at different times from 2007 through 2011. This paper summarizes geophysical results from the 4-year monitoring study of the SDI system.

Thaumarchaeal ammonium oxidation and evidence for a nitrogen cycle in a subsurface radioactive thermal spring in the Austrian Central Alps.

PubMed

Gerbl, Friedrich W; Weidler, Gerhard W; Wanek, Wolfgang; Erhardt, Angelika; Stan-Lotter, Helga

2014-01-01

Previous studies had suggested the presence of ammonium oxidizing Thaumarchaeota as well as nitrite oxidizing Bacteria in the subsurface spring called Franz Josef Quelle (FJQ), a slightly radioactive thermal mineral spring with a temperature of 43.6-47°C near the alpine village of Bad Gastein, Austria. The microbiological consortium of the FJQ was investigated for its utilization of nitrogen compounds and the putative presence of a subsurface nitrogen cycle. Microcosm experiments made with samples from the spring water, containing planktonic microorganisms, or from biofilms, were used in this study. Three slightly different media, enriched with vitamins and trace elements, and two incubation temperatures (30 and 40°C, respectively) were employed. Under aerobic conditions, high rates of conversion of ammonium to nitrite, as well as nitrite to nitrate were measured. Under oxygen-limited conditions nitrate was converted to gaseous compounds. Stable isotope probing with (15)NH4Cl or ((15)NH4)2SO4as sole energy sources revealed incorporation of (15)N into community DNA. Genomic DNA as well as RNA were extracted from all microcosms. The following genes or fragments of genes were successfully amplified, cloned and sequenced by standard PCR from DNA extracts: Ammonia monooxygenase subunit A (amoA), nitrite oxidoreductase subunits A and B (nxrA and nxrB), nitrate reductase (narG), nitrite reductase (nirS), nitric oxide reductases (cnorB and qnorB), nitrous oxide reductase (nosZ). Reverse transcription of extracted total RNA and real-time PCR suggested the expression of each of those genes. Nitrogen fixation (as probed with nifH and nifD) was not detected. However, a geological origin of NH(+) 4 in the water of the FJQ cannot be excluded, considering the silicate, granite and gneiss containing environment. The data suggested the operation of a nitrogen cycle in the subsurface environment of the FJQ.

Thaumarchaeal ammonium oxidation and evidence for a nitrogen cycle in a subsurface radioactive thermal spring in the Austrian Central Alps

PubMed Central

Gerbl, Friedrich W.; Weidler, Gerhard W.; Wanek, Wolfgang; Erhardt, Angelika; Stan-Lotter, Helga

2014-01-01

Previous studies had suggested the presence of ammonium oxidizing Thaumarchaeota as well as nitrite oxidizing Bacteria in the subsurface spring called Franz Josef Quelle (FJQ), a slightly radioactive thermal mineral spring with a temperature of 43.6–47°C near the alpine village of Bad Gastein, Austria. The microbiological consortium of the FJQ was investigated for its utilization of nitrogen compounds and the putative presence of a subsurface nitrogen cycle. Microcosm experiments made with samples from the spring water, containing planktonic microorganisms, or from biofilms, were used in this study. Three slightly different media, enriched with vitamins and trace elements, and two incubation temperatures (30 and 40°C, respectively) were employed. Under aerobic conditions, high rates of conversion of ammonium to nitrite, as well as nitrite to nitrate were measured. Under oxygen-limited conditions nitrate was converted to gaseous compounds. Stable isotope probing with 15NH4Cl or (15NH4)2SO4as sole energy sources revealed incorporation of 15N into community DNA. Genomic DNA as well as RNA were extracted from all microcosms. The following genes or fragments of genes were successfully amplified, cloned and sequenced by standard PCR from DNA extracts: Ammonia monooxygenase subunit A (amoA), nitrite oxidoreductase subunits A and B (nxrA and nxrB), nitrate reductase (narG), nitrite reductase (nirS), nitric oxide reductases (cnorB and qnorB), nitrous oxide reductase (nosZ). Reverse transcription of extracted total RNA and real-time PCR suggested the expression of each of those genes. Nitrogen fixation (as probed with nifH and nifD) was not detected. However, a geological origin of NH+4 in the water of the FJQ cannot be excluded, considering the silicate, granite and gneiss containing environment. The data suggested the operation of a nitrogen cycle in the subsurface environment of the FJQ. PMID:24904540

The Correlation between Radon Emission Concentration and Subsurface Geological Condition

NASA Astrophysics Data System (ADS)

Kuntoro, Yudi; Setiawan, Herru L.; Wijayanti, Teni; Haerudin, Nandi

2018-03-01

Exploration activities with standard methods have already encountered many obstacles in the field. Geological survey is often difficult to find outcrop because they are covered by vegetation, alluvial layer or as a result of urban development and housing. Seismic method requires a large expense and licensing in the use of dynamite is complicated. Method of gravity requires the operator to go back (looping) to the starting point. Given some of these constraints, therefore it needs a solution in the form of new method that can work more efficiently with less cost. Several studies in various countries have shown a correlation between the presence of hydrocarbons and Radon gas concentration in the earth surface. By utilizing the properties of Radon that can migrate to the surface, the value of Radon concentration in the surface is suggested to provide information about the subsurface structure condition. Radon is the only radioactive substance that gas-phased at atmospheric temperature. It is very abundant in the earth mantle. The vast differences of temperatures and pressures between the mantle and the earth crust cause the convection flow toward earth surface. Radon in gas phase will be carried by convection flow to the surface. The quantity of convection currents depend on the porosity and permeability of rocks where Radon travels within, so that Radon concentration in the earth surface delineates the porosity and permeability of subsurface rock layers. Some measurements were carried out at several locations with various subsurface geological conditions, including proven oil fields, proven geothermal field, and frontier area as a comparison. These measurements show that the average and the background concentration threshold in the proven oil field (11,200 Bq/m3) and proven geothermal field (7,820 Bq/m3) is much higher than the quantity in frontier area (329 and 1,620 Bq/m3). Radon concentration in the earth surface is correlated with the presence of geological faults. Peak concentrations of Radon takes place along the fault.

The significance of "geothermal microzonation" for the correct planning of low-grade source geothermal systems

NASA Astrophysics Data System (ADS)

Viccaro, Marco; Pezzino, Antonino; Belfiore, Giuseppe Maria; Campisano, Carlo

2016-04-01

Despite the environmental-friendly energy systems are solar thermal technologies, photovoltaic and wind power, other advantageous technologies exist, although they have not found wide development in countries such as Italy. Given the almost absent environmental impact and the rather favorable cost/benefit ratio, low-enthalpy geothermal systems are, however, likely to be of strategic importance also in Italy during the next years. The importance of geology for a sustainable exploitation of the ground through geothermal systems from low-grade sources is becoming paramount. Specifically, understanding of the lithological characteristics of the subsurface along with structures and textures of rocks is essential for a correct planning of the probe/geo-exchanger field and their associated ground source heat pumps. The complex geology of Eastern Sicily (Southern Italy), which includes volcanic, sedimentary and metamorphic units over limited extension, poses the question of how thermal conductivity of rocks is variable at the scale of restricted areas (even within the same municipality). This is the innovative concept of geothermal microzonation, i.e., how variable is the geothermal potential as a function of geology at the microscale. Some pilot areas have been therefore chosen to test how the geological features of the subsurface can influence the low-enthalpy geothermal potential of an area. Our geologically based evaluation and micro-zonation of the low-grade source geothermal potential of the selected areas have been verified to be fundamental for optimization of all the main components of a low-enthalpy geothermal system. Saving realization costs and limiting the energy consumption through correct sizing of the system are main ambitions to have sustainable development of this technology with intensive utilization of the subsurface. The variegated territory of countries such as Italy implies that these goals can be only reached if, primarily, the geological features of the shallow subsurface (i.e., chemical-physical characteristics of rocks and fluids of the first 100 m below the ground) are appropriately constrained.

Micrometeorological and Soil Data for Calculating Evapotranspiration for Rainier Mesa, Nevada Test Site, Nevada, 2002-05

USGS Publications Warehouse

DeMeo, Guy A.; Flint, Alan L.; Laczniak, Randell J.; Nylund, Walter E.

2006-01-01

Micrometeorological and soil-moisture data were collected at two instrumented sites on Rainier Mesa at the Nevada Test Site, January 1, 2002 - August 23, 2005. Data collected at each site include net radiation, air temperature, and relative humidity at two heights; wind speed and direction; subsurface soil heat flux; subsurface soil temperature; volumetric soil water; and matric water potential. These data were used to estimate 20-minute average and daily average evapotranspiration values. The data presented in this report are collected and calculated evapotranspiration rates.

Modeling Aspect Controlled Formation of Seasonally Frozen Ground on Montane Hillslopes: a Case Study from Gordon Gulch, Colorado

NASA Astrophysics Data System (ADS)

Rush, M.; Rajaram, H.; Anderson, R. S.; Anderson, S. P.

2017-12-01

The Intergovernmental Panel on Climate Change (2013) warns that high-elevation ecosystems are extremely vulnerable to climate change due to short growing seasons, thin soils, sparse vegetation, melting glaciers, and thawing permafrost. Many permafrost-free regions experience seasonally frozen ground. The spatial distribution of frozen soil exerts a strong control on subsurface flow and transport processes by reducing soil permeability and impeding infiltration. Accordingly, evolution of the extent and duration of frozen ground may alter streamflow seasonality, groundwater flow paths, and subsurface storage, presenting a need for coupled thermal-hydrologic models to project hydrologic responses to climate warming in high-elevation regions. To be useful as predictive tools, such models should incorporate the heterogeneity of solar insolation, vegetation, and snowpack dynamics. We present a coupled thermal-hydrologic modeling study against the backdrop of field observations from Gordon Gulch, a seasonally snow-covered montane catchment in the Colorado Front Range in the Boulder Creek Critical Zone Observatory. The field site features two instrumented hillslopes with opposing aspects: the snowpack on the north-facing slope persists throughout much of the winter season, while the snowpack on the south-facing slope is highly ephemeral. We implemented a surface energy balance and snowpack accumulation and ablation model that is coupled to the subsurface flow and transport code PFLOTRAN-ICE to predict the hydrologic consequences of aspect-controlled frozen soil formation during water years 2013-2016. Preliminary model results demonstrate the occurrence of seasonally-frozen ground on the north-facing slope that directs snowmelt to the stream by way of shallow subsurface flow paths. The absence of persistently frozen ground on the south-facing slope allows deeper infiltration of snowmelt recharge. The differences in subsurface flow paths also suggest strong aspect-controlled heterogeneities in nitrate export and differences in geomorphic processes such as frost creep.

Geoelectrical monitoring of simulated subsurface leakage to support high-hazard nuclear decommissioning at the Sellafield Site, UK.

PubMed

Kuras, Oliver; Wilkinson, Paul B; Meldrum, Philip I; Oxby, Lucy S; Uhlemann, Sebastian; Chambers, Jonathan E; Binley, Andrew; Graham, James; Smith, Nicholas T; Atherton, Nick

2016-10-01

A full-scale field experiment applying 4D (3D time-lapse) cross-borehole Electrical Resistivity Tomography (ERT) to the monitoring of simulated subsurface leakage was undertaken at a legacy nuclear waste silo at the Sellafield Site, UK. The experiment constituted the first application of geoelectrical monitoring in support of decommissioning work at a UK nuclear licensed site. Images of resistivity changes occurring since a baseline date prior to the simulated leaks revealed likely preferential pathways of silo liquor simulant flow in the vadose zone and upper groundwater system. Geophysical evidence was found to be compatible with historic contamination detected in permeable facies in sediment cores retrieved from the ERT boreholes. Results indicate that laterally discontinuous till units forming localized hydraulic barriers substantially affect flow patterns and contaminant transport in the shallow subsurface at Sellafield. We conclude that only geophysical imaging of the kind presented here has the potential to provide the detailed spatial and temporal information at the (sub-)meter scale needed to reduce the uncertainty in models of subsurface processes at nuclear sites. Copyright © 2016 British Geological Survey, NERC. Published by Elsevier B.V. All rights reserved.

Integration of the subsurface and the surface sectors for a more holistic approach for sustainable redevelopment of urban brownfields.

PubMed

Norrman, Jenny; Volchko, Yevheniya; Hooimeijer, Fransje; Maring, Linda; Kain, Jaan-Henrik; Bardos, Paul; Broekx, Steven; Beames, Alistair; Rosén, Lars

2016-09-01

This paper presents a holistic approach to sustainable urban brownfield redevelopment where specific focus is put on the integration of a multitude of subsurface qualities in the early phases of the urban redevelopment process, i.e. in the initiative and plan phases. Achieving sustainability in brownfield redevelopment projects may be constrained by a failure of engagement between two key expert constituencies: urban planners/designers and subsurface engineers, leading to missed opportunities and unintended outcomes in the plan realisation phase. A more integrated approach delivers greater benefits. Three case studies in the Netherlands, Belgium and Sweden were used to test different sustainability assessment instruments in terms of the possibility for knowledge exchange between the subsurface and the surface sectors and in terms of cooperative learning among experts and stakeholders. Based on the lessons learned from the case studies, a generic decision process framework is suggested that supports holistic decision making. The suggested framework focuses on stakeholder involvement, communication, knowledge exchange and learning and provides an inventory of instruments that can support these processes. Copyright © 2016 Elsevier B.V. All rights reserved.

Design of combination biofilter and subsurface constructed wetland-multilayer filtration with vertical flow type using Vetiveria zizanioides (akar wangi)

NASA Astrophysics Data System (ADS)

Astuti, A. D.; Lindu, M.; Yanidar, R.; Faruq, M.

2018-01-01

As environmental regulation has become stricter in recent years, there is an increasing concern about the issue of wastewater treatment in urban areas. Senior High School as center of student activity has a potential source to generated domestic wastewater from toilet, bathroom and canteen. Canteen wastewater contains high-organic content that to be treated before discharged. Based on previous research the subsurface constructed wetland-multilayer filtration with vertical flow is an attractive alternative to provide efficient treatment of canteen wastewater. The effluent concentration complied with regulation according to [9]. Due to limited land, addition of preliminary treatment such as the presence of biofilter was found to improve the performance. The aim of this study was to design combination biofilter and subsurface constructed wetland-multilayer filtration with vertical flow type using vetiveria zizanioides (akar wangi) treating canteen wastewater. Vetiveria zizanioides (akar wangi) is used because from previous research, subsurface constructed wetland-multilayer filtration (SCW-MLF) with vertical flow type using vetiveria zizanioides (akar wangi) can be an alternative canteen wastewater treatment that is uncomplicated in technology, low cost in operational and have a beautiful landscape view, besides no odors or insects were presented during the operation.

Investigation of North Pond crustal fluids by poised potential methods

NASA Astrophysics Data System (ADS)

Jones, R. M.; Orcutt, B.

2017-12-01

Microbes are present in the deep subsurface but their rates of activity, potential metabolisms and roles in the environment are still largely unknown. The marine deep crustal subsurface accounts for approximately 2.3x1018 m2 of the earth's volume, making this environment potentially significant to earth processes despite low productivity inherent in resource limited conditions. This has implications for geochemical cycling and exploring limits of life, linking to the `follow the energy' approach for defining habitability on earth and further afield. Most resources for life in the marine deep crust originate from rock. One subset of lithotrophic interactions involves direct transfer between electron acceptors and donors embedded in minerals and microbes. In this investigation, poised potential methods such as chronoamperometry were used to investigate mineral-microbe electron transfer interactions in the context of North Pond, a Mid-Atlantic ridge site representative of cool, sediment-covered basalts that make up the majority of the deep marine subsurface. Electrodes were poised at potentials corresponding approximately to particular lithotrophic oxidation reactions to enrich for sub-sections of North Pond deep subsurface fluid communities that were associated with direct electron transfer at these potentials.

A new solar cycle model including meridional circulation

NASA Technical Reports Server (NTRS)

Wang, Y.-M.; Sheeley, N. R., Jr.; Nash, A. G.

1991-01-01

A kinematic model is presented for the solar cycle which includes not only the transport of magnetic flux by supergranular diffusion and a poleward bulk flow at the sun's surface, but also the effects of turbulent diffusion and an equatorward 'return flow' beneath the surface. As in the earlier models of Babcock and Leighton, the rotational shearing of a subsurface poloidal field generates toroidal flux that erupts at the surface in the form of bipolar magnetic regions. However, such eruptions do not result in any net loss of toroidal flux from the sun (as assumed by Babcock and Leighton); instead, the large-scale toroidal field is destroyed both by 'unwinding' as the local poloidal field reverses its polarity, and by diffusion as the toroidal flux is transported equatorward by the subsurface flow and merged with its opposite hemisphere counterpart. The inclusion of meridional circulation allows stable oscillations of the magnetic field, accompanied by the equatorward progression of flux eruptions, to be achieved even in the absence of a radial gradient in the angular velocity. An illustrative case in which a subsurface flow speed of order 1 m/s and subsurface diffusion rate of order 10 sq km/s yield 22-yr oscillations in qualitative agreement with observations.

Sub-surface structure of La Soufrière of Guadeloupe lava dome deduced from a ground-based magnetic survey

NASA Astrophysics Data System (ADS)

Bouligand, Claire; Coutant, Olivier; Glen, Jonathan M. G.

2016-07-01

In this study, we present the analysis and interpretation of a new ground magnetic survey acquired at the Soufrière volcano on Guadeloupe Island. Observed short-wavelength magnetic anomalies are compared to those predicted assuming a constant magnetization within the sub-surface. The good correlation between modeled and observed data over the summit of the dome indicates that the shallow sub-surface displays relatively constant and high magnetization intensity. In contrast, the poor correlation at the base of the dome suggests that the underlying material is non- to weakly-magnetic, consistent with what is expected for a talus comprised of randomly oriented and highly altered and weathered boulders. The new survey also reveals a dipole anomaly that is not accounted for by a constant magnetization in the sub-surface and suggests the existence of material with decreased magnetization beneath the Soufrière lava dome. We construct simple models to constrain its dimensions and propose that this body corresponds to hydrothermally altered material within and below the dome. The very large inferred volume for such material may have implications on the stability of the dome.

Methane clathrate stability zone variations and gas transport in the Martian subsurface

NASA Astrophysics Data System (ADS)

Karatekin, O.; Gloesener, E.; Dehant, V. M. A.; Temel, O.

2016-12-01

During the last years, several detections of methane in the atmosphere of Mars were reported from Earth-based and Mars orbit instruments with abundances ranging to tens of parts-per-billion by volume (ppbv). Recently, the Curiosity rover detected methane with background levels of 0.7 ppbv and episodic releases of 7 ppbv. Although the methane sources are still unknown, this gas may have been stored in reservoirs of clathrate hydrate in the Martian subsurface where thermodynamics conditions are favourable to their presence. Clathrate hydrates are crystalline compounds constituted by cages formed by hydrogen-bonded water molecules inside of which guest gas molecules are trapped. In this study, methane clathrate stability in the Martian subsurface are investigated and their temporal and spatial variations are studied. Present-day maps of methane clathrate stability zone are produced by coupling the stability conditions of methane clathrate with a subsurface model using the available observations such as the the thermal inertia derived from TES MGS data. Then, a gas transport model has been used to study the methane flux at the surface due to the diffusion of different plausible methane volumes released by clathrate hydrates at variable depths under the Martian surface.

Platforms for hyperspectral imaging, in-situ optical and acoustical imaging in urbanized regions

NASA Astrophysics Data System (ADS)

Bostater, Charles R.; Oney, Taylor

2016-10-01

Hyperspectral measurements of the water surface of urban coastal waters are presented. Oblique bidirectional reflectance factor imagery was acquired made in a turbid coastal sub estuary of the Indian River Lagoon, Florida and along coastal surf zone waters of the nearby Atlantic Ocean. Imagery was also collected using a pushbroom hyperspectral imager mounted on a fixed platform with a calibrated circular mechatronic rotation stage. Oblique imagery of the shoreline and subsurface features clearly shows subsurface bottom features and rip current features within the surf zone water column. In-situ hyperspectral optical signatures were acquired from a vessel as a function of depth to determine the attenuation spectrum in Palm Bay. A unique stationary platform methodology to acquire subsurface acoustic images showing the presence of moving bottom boundary nephelometric layers passing through the acoustic fan beam. The acoustic fan beam imagery indicated the presence of oscillatory subsurface waves in the urbanized coastal estuary. Hyperspectral imaging using the fixed platform techniques are being used to collect hyperspectral bidirectional reflectance factor (BRF) measurements from locations at buildings and bridges in order to provide new opportunities to advance our scientific understanding of aquatic environments in urbanized regions.

Sequential geophysical and flow inversion to characterize fracture networks in subsurface systems

DOE PAGES

Mudunuru, Maruti Kumar; Karra, Satish; Makedonska, Nataliia; ...

2017-09-05

Subsurface applications, including geothermal, geological carbon sequestration, and oil and gas, typically involve maximizing either the extraction of energy or the storage of fluids. Fractures form the main pathways for flow in these systems, and locating these fractures is critical for predicting flow. However, fracture characterization is a highly uncertain process, and data from multiple sources, such as flow and geophysical are needed to reduce this uncertainty. We present a nonintrusive, sequential inversion framework for integrating data from geophysical and flow sources to constrain fracture networks in the subsurface. In this framework, we first estimate bounds on the statistics formore » the fracture orientations using microseismic data. These bounds are estimated through a combination of a focal mechanism (physics-based approach) and clustering analysis (statistical approach) of seismic data. Then, the fracture lengths are constrained using flow data. In conclusion, the efficacy of this inversion is demonstrated through a representative example.« less

Contamination and restoration of groundwater aquifers.

PubMed Central

Piver, W T

1993-01-01

Humans are exposed to chemicals in contaminated groundwaters that are used as sources of drinking water. Chemicals contaminate groundwater resources as a result of waste disposal methods for toxic chemicals, overuse of agricultural chemicals, and leakage of chemicals into the subsurface from buried tanks used to hold fluid chemicals and fuels. In the process, both the solid portions of the subsurface and the groundwaters that flow through these porous structures have become contaminated. Restoring these aquifers and minimizing human exposure to the parent chemicals and their degradation products will require the identification of suitable biomarkers of human exposure; better understandings of how exposure can be related to disease outcome; better understandings of mechanisms of transport of pollutants in the heterogeneous structures of the subsurface; and field testing and evaluation of methods proposed to restore and cleanup contaminated aquifers. In this review, progress in these many different but related activities is presented. PMID:8354172

Sequential geophysical and flow inversion to characterize fracture networks in subsurface systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mudunuru, Maruti Kumar; Karra, Satish; Makedonska, Nataliia

Subsurface applications, including geothermal, geological carbon sequestration, and oil and gas, typically involve maximizing either the extraction of energy or the storage of fluids. Fractures form the main pathways for flow in these systems, and locating these fractures is critical for predicting flow. However, fracture characterization is a highly uncertain process, and data from multiple sources, such as flow and geophysical are needed to reduce this uncertainty. We present a nonintrusive, sequential inversion framework for integrating data from geophysical and flow sources to constrain fracture networks in the subsurface. In this framework, we first estimate bounds on the statistics formore » the fracture orientations using microseismic data. These bounds are estimated through a combination of a focal mechanism (physics-based approach) and clustering analysis (statistical approach) of seismic data. Then, the fracture lengths are constrained using flow data. In conclusion, the efficacy of this inversion is demonstrated through a representative example.« less

The InSight Mars Lander and Its Effect on the Subsurface Thermal Environment

NASA Astrophysics Data System (ADS)

Siegler, Matthew A.; Smrekar, Suzanne E.; Grott, Matthias; Piqueux, Sylvain; Mueller, Nils; Williams, Jean-Pierre; Plesa, Ana-Catalina; Spohn, Tilman

2017-10-01

The 2018 InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) Mission has the mission goal of providing insitu data for the first measurement of the geothermal heat flow of Mars. The Heat Flow and Physical Properties Package (HP3) will take thermal conductivity and thermal gradient measurements to approximately 5 m depth. By necessity, this measurement will be made within a few meters of the lander. This means that thermal perturbations from the lander will modify local surface and subsurface temperature measurements. For HP3's sensitive thermal gradient measurements, this spacecraft influence will be important to model and parameterize. Here we present a basic 3D model of thermal effects of the lander on its surroundings. Though lander perturbations significantly alter subsurface temperatures, a successful thermal gradient measurement will be possible in all thermal conditions by proper (>3 m depth) placement of the heat flow probe.

Statistical Analysis of Small-Scale Magnetic Flux Emergence Patterns: A Useful Subsurface Diagnostic?

NASA Astrophysics Data System (ADS)

Lamb, Derek A.

2016-10-01

While sunspots follow a well-defined pattern of emergence in space and time, small-scale flux emergence is assumed to occur randomly at all times in the quiet Sun. HMI's full-disk coverage, high cadence, spatial resolution, and duty cycle allow us to probe that basic assumption. Some case studies of emergence suggest that temporal clustering on spatial scales of 50-150 Mm may occur. If clustering is present, it could serve as a diagnostic of large-scale subsurface magnetic field structures. We present the results of a manual survey of small-scale flux emergence events over a short time period, and a statistical analysis addressing the question of whether these events show spatio-temporal behavior that is anything other than random.

Femtosecond laser micro-inscription of optical coherence tomography resolution test artifacts.

PubMed

Tomlins, Peter H; Smith, Graham N; Woolliams, Peter D; Rasakanthan, Janarthanan; Sugden, Kate

2011-04-25

Optical coherence tomography (OCT) systems are becoming more commonly used in biomedical imaging and, to enable continued uptake, a reliable method of characterizing their performance and validating their operation is required. This paper outlines the use of femtosecond laser subsurface micro-inscription techniques to fabricate an OCT test artifact for validating the resolution performance of a commercial OCT system. The key advantage of this approach is that by utilizing the nonlinear absorption a three dimensional grid of highly localized point and line defects can be written in clear fused silica substrates.

Miniature near-infrared dual-axes confocal microscope utilizing a two-dimensional microelectromechanical systems scanner

PubMed Central

Liu, Jonathan T. C.; Mandella, Michael J.; Ra, Hyejun; Wong, Larry K.; Solgaard, Olav; Kino, Gordon S.; Piyawattanametha, Wibool; Contag, Christopher H.; Wang, Thomas D.

2007-01-01

The first, to our knowledge, miniature dual-axes confocal microscope has been developed, with an outer diameter of 10 mm, for subsurface imaging of biological tissues with 5–7 μm resolution. Depth-resolved en face images are obtained at 30 frames per second, with a field of view of 800 × 100 μm, by employing a two-dimensional scanning microelectromechanical systems mirror. Reflectance and fluorescence images are obtained with a laser source at 785 nm, demonstrating the ability to perform real-time optical biopsy. PMID:17215937

The subsurface geology of Río Tinto: material examined during a simulated Mars drilling mission for the Mars Astrobiology Research and Technology Experiment (MARTE).

PubMed

Prieto-Ballesteros, Olga; Martínez-Frías, Jesús; Schutt, John; Sutter, Brad; Heldmann, Jennifer L; Bell, Mary Sue; Battler, Melissa; Cannon, Howard; Gómez-Elvira, Javier; Stoker, Carol R

2008-10-01

The 2005 Mars Astrobiology Research and Technology Experiment (MARTE) project conducted a simulated 1-month Mars drilling mission in the Río Tinto district, Spain. Dry robotic drilling, core sampling, and biological and geological analytical technologies were collectively tested for the first time for potential use on Mars. Drilling and subsurface sampling and analytical technologies are being explored for Mars because the subsurface is the most likely place to find life on Mars. The objectives of this work are to describe drilling, sampling, and analytical procedures; present the geological analysis of core and borehole material; and examine lessons learned from the drilling simulation. Drilling occurred at an undisclosed location, causing the science team to rely only on mission data for geological and biological interpretations. Core and borehole imaging was used for micromorphological analysis of rock, targeting rock for biological analysis, and making decisions regarding the next day's drilling operations. Drilling reached 606 cm depth into poorly consolidated gossan that allowed only 35% of core recovery and contributed to borehole wall failure during drilling. Core material containing any indication of biology was sampled and analyzed in more detail for its confirmation. Despite the poorly consolidated nature of the subsurface gossan, dry drilling was able to retrieve useful core material for geological and biological analysis. Lessons learned from this drilling simulation can guide the development of dry drilling and subsurface geological and biological analytical technologies for future Mars drilling missions.

The Subsurface Geology of Río Tinto: Material Examined During a Simulated Mars Drilling Mission for the Mars Astrobiology Research and Technology Experiment (MARTE)

NASA Astrophysics Data System (ADS)

Prieto-Ballesteros, Olga; Martínez-Frías, Jesús; Schutt, John; Sutter, Brad; Heldmann, Jennifer L.; Bell Johnson, Mary Sue; Battler, Melissa; Cannon, Howard; Gómez-Elvira, Javier; Stoker, Carol R.

2008-10-01

The 2005 Mars Astrobiology Research and Technology Experiment (MARTE) project conducted a simulated 1-month Mars drilling mission in the Río Tinto district, Spain. Dry robotic drilling, core sampling, and biological and geological analytical technologies were collectively tested for the first time for potential use on Mars. Drilling and subsurface sampling and analytical technologies are being explored for Mars because the subsurface is the most likely place to find life on Mars. The objectives of this work are to describe drilling, sampling, and analytical procedures; present the geological analysis of core and borehole material; and examine lessons learned from the drilling simulation. Drilling occurred at an undis closed location, causing the science team to rely only on mission data for geological and biological interpretations. Core and borehole imaging was used for micromorphological analysis of rock, targeting rock for biological analysis, and making decisions regarding the next day's drilling operations. Drilling reached 606 cm depth into poorly consolidated gossan that allowed only 35% of core recovery and contributed to borehole wall failure during drilling. Core material containing any indication of biology was sampled and analyzed in more detail for its confirmation. Despite the poorly consolidated nature of the subsurface gossan, dry drilling was able to retrieve useful core material for geological and biological analysis. Lessons learned from this drilling simulation can guide the development of dry drilling and subsurface geological and biological analytical technologies for future Mars drilling missions.

Survival in the hot subsurface: Hydrogen stress on hyperthermophilic heterotrophs and methanogens

NASA Astrophysics Data System (ADS)

Topcuoglu, B. D.; Holden, J. F.

2017-12-01

Marine hyperthermophilic heterotrophs and methanogens belonging to the Thermococcales and Methanococcales are often found in hot subsurface environments such as hydrothermal vents, marine sediments, and oil reservoirs. This project aims to make fundamental advances in our understanding of interspecies microbe-microbe interactions in hot subsurface environments by integrating metabolic network modeling, transcriptomic analyses and continuous cultivation of hyperthermophiles and describe how heterotrophs and methanogens eliminate H2 stress. Some subsurface environments may lack alternative electron acceptors (e.g., S°) for the heterotroph and sufficient environmental flux rates to draw in fresh energy sources or remove excess metabolic products. We observed a decrease in growth rates for the H2-producer Thermococcus paralvinellae when grown with an aqueous H2 background of 65 µM relative to no added H2. Metabolite analysis showed increased formate production during H2 inhibition. Differential gene expression analyses coupled with metabolic network modeling showed that T. paralvinellae oxidized H2 and made formate by a formate hydrogenlyase to survive H2 inhibition. Low H2 concentrations (20 µM) also caused a decrease in growth and CH4 production rates for the H2-consuming methanogen Methanocaldococcus jannaschii. H2 stress in both organisms was ameliorated when the organisms were grown together syntrophically. CH4 was produced without any added H2 during syntrophic growth, and there was no formate produced by T. paralvinellae. These organisms may impact the biogeochemistry, especially natural gas production, in saline, organic-rich subsurface environments when both are present.

The Limits of Life in the Deep Subsurface - Implications for the Origin of Life

NASA Astrophysics Data System (ADS)

Baross, John

2013-06-01

There are very few environments on Earth where life is absent. Microbial life has proliferated into habitats that span nearly every imaginable physico-chemical variable. Only the availability of liquid water and temperature are known to prevent the growth of organisms. The other extreme physical and chemical variables, such as pH, pressure, high concentrations of solutes, damaging radiation, and toxic metals, are life-prohibiting factors for most organisms but not for all. The deep subsurface environments span all of the extreme conditions encountered by life including habitat conditions not yet explored, such as those that combine high temperature, high and low pH and extreme pressures. Some of the ``extremophile'' microorganisms inhabiting the deep subsurface environments have been shown to be among the most ``ancient'' of extant life. Their genomes and physiologies have led to a broader understanding of the geological settings of early life, the most ancient energy pathways, and the importance of water/rock interactions and tectonics in the origin and early evolution of life. The case can now be made that deep subsurface environments contributed to life's origin and provided the habitat(s) for the earliest microbial communities. However, there is much more to be done to further our understanding on the role of moderate to high pressures and temperatures on the chemical and biochemical ``steps'' leading to life, and on the evolution and physiology of both ancient and present-day subsurface microbial communities.

Large temporal scale and capacity subsurface bulk energy storage with CO2

NASA Astrophysics Data System (ADS)

Saar, M. O.; Fleming, M. R.; Adams, B. M.; Ogland-Hand, J.; Nelson, E. S.; Randolph, J.; Sioshansi, R.; Kuehn, T. H.; Buscheck, T. A.; Bielicki, J. M.

2017-12-01

Decarbonizing energy systems by increasing the penetration of variable renewable energy (VRE) technologies requires efficient and short- to long-term energy storage. Very large amounts of energy can be stored in the subsurface as heat and/or pressure energy in order to provide both short- and long-term (seasonal) storage, depending on the implementation. This energy storage approach can be quite efficient, especially where geothermal energy is naturally added to the system. Here, we present subsurface heat and/or pressure energy storage with supercritical carbon dioxide (CO2) and discuss the system's efficiency, deployment options, as well as its advantages and disadvantages, compared to several other energy storage options. CO2-based subsurface bulk energy storage has the potential to be particularly efficient and large-scale, both temporally (i.e., seasonal) and spatially. The latter refers to the amount of energy that can be stored underground, using CO2, at a geologically conducive location, potentially enabling storing excess power from a substantial portion of the power grid. The implication is that it would be possible to employ centralized energy storage for (a substantial part of) the power grid, where the geology enables CO2-based bulk subsurface energy storage, whereas the VRE technologies (solar, wind) are located on that same power grid, where (solar, wind) conditions are ideal. However, this may require reinforcing the power grid's transmission lines in certain parts of the grid to enable high-load power transmission from/to a few locations.

Geomicrobiology and Metagenomics of Terrestrial Deep Subsurface Microbiomes.

PubMed

Itävaara, M; Salavirta, H; Marjamaa, K; Ruskeeniemi, T

2016-01-01

Fractures in the deep subsurface of Earth's crust are inhabited by diverse microbial communities that participate in biogeochemical cycles of the Earth. Life on Earth, which arose c. 3.5-4.0 billion years ago, reaches down at least 5 km in the crust. Deep mines, caves, and boreholes have provided scientists with opportunities to sample deep subsurface microbiomes and to obtain information on the species diversity and functions. A wide variety of bacteria, archaea, eukaryotes, and viruses are now known to reside in the crust, but their functions are still largely unknown. The crust at different depths has varying geological composition and hosts endemic microbiomes accordingly. The diversity is driven by geological formations and gases evolving from deeper depths. Cooperation among different species is still mostly unexplored, but viruses are known to restrict density of bacterial and archaeal populations. Due to the complex growth requirements of the deep subsurface microbiomes, the new knowledge about their diversity and functions is mostly obtained by molecular methods, eg, meta'omics'. Geomicrobiology is a multidisciplinary research area combining disciplines from geology, mineralogy, geochemistry, and microbiology. Geomicrobiology is concerned with the interaction of microorganisms and geological processes. At the surface of mineralogical or rock surfaces, geomicrobial processes occur mainly under aerobic conditions. In the deep subsurface, however, the environmental conditions are reducing and anaerobic. The present chapter describes the world of microbiomes in deep terrestrial geological environments as well as metagenomic and metatranscriptomic methods suitable for studies of these enigmatic communities. Copyright © 2016 Elsevier Inc. All rights reserved.

Actinobacterial diversity across a marine transgression in the deep subsurface off Shimokita Peninsula, Japan

NASA Astrophysics Data System (ADS)

Harrison, B. K.; Bailey, J. V.

2013-12-01

Sediment horizons represent a significant - but not permanent - barrier to microbial transport. Cells commonly attach to mineral surfaces in unconsolidated sediments. However, by taxis, growth, or passive migration under advecting fluids, some portion of the microbial community may transgress sedimentary boundaries. Few studies have attempted to constrain such transport of community signatures in the marine subsurface and its potential impact on biogeography. Integrated Ocean Drilling Program (IODP) Expedition 337 off the Shimokita Peninsula recovered sediments over a greater than 1km interval representing a gradual decrease of terrestrial influence, from tidal to continental shelf depositional settings. This sequence represents a key opportunity to link subsurface microbial communities to lithological variability and investigate the permanence of community signatures characteristic of distinct depositional regimes. The phylogenetic connectivity between marine and terrestrially-influenced deposits may demonstrate to what degree sediments offer a substantial barrier to cell transport in the subsurface. Previous work has demonstrated that the Actinobacterial phylum is broadly distributed in marine sediments (Maldonado et al., 2005), present and active in the deep subsurface (Orsi et al., 2013), and that marine and terrestrial lineages may potentially be distinguished by 16S rRNA gene sequencing (e.g. Prieto-Davó et al., 2013). We report on Actinobacteria-specific 16S rRNA gene diversity recovered between 1370 and 2642 mbsf with high-throughput sequencing using the Illumina MiSeq platform, as well as selective assembly and analysis of environmental clone libraries.

Microstructure and Tribological Properties of Mo–40Ni–13Si Multiphase Intermetallic Alloy

PubMed Central

Song, Chunyan; Wang, Shuhuan; Gui, Yongliang; Cheng, Zihao; Ni, Guolong

2016-01-01

Intermetallic compounds are increasingly being expected to be utilized in tribological environments, but to date their implementation is hindered by insufficient ductility at low and medium temperatures. This paper presents a novel multiphase intermetallic alloy with the chemical composition of Mo–40Ni–13Si (at %). Microstructure characterization reveals that a certain amount of ductile Mo phases formed during the solidification process of a ternary Mo–Ni–Si molten alloy, which is beneficial to the improvement of ductility of intermetallic alloys. Tribological properties of the designed alloy—including wear resistance, friction coefficient, and metallic tribological compatibility—were evaluated under dry sliding wear test conditions at room temperature. Results suggest that the multiphase alloy possesses an excellent tribological property, which is attributed to unique microstructural features and thereby a good combination in hardness and ductility. The corresponding wear mechanism is explained by observing the worn surface, subsurface, and wear debris of the alloy, which was found to be soft abrasive wear. PMID:28774106

Gravimetric determination of the Thickness of Taku Glacier: Impact of Glacier Thickness on Subglacial Hydrology and Potential Erosion

NASA Astrophysics Data System (ADS)

Hamm, T. G.; Borthwick, L.; Jarrin, D.; Miller, M.; Wall, R.; Beem, L.; Riverman, K. L.

2016-12-01

High resolution measurements of spatial ice thickness variability on the Juneau Icefield are critical to an understanding of current glacial dynamics in the Coast Mountains of Southeast Alaska. In particular, such data are lacking on the Taku Glacier, a tidewater glacier in the Juneau region whose unique advance has slowed in recent years. Significantly, such information is necessary to develop an accurate description of ice dynamics as well as sub-surface hydrology and bedrock erosion. Utilizing relative gravimetry, we sought to modify existing parameterized models of ice thickness with field measurements taken along the centerline of the Taku. Here we present a three-dimensional representation of ice thickness for the Taku, based on in situ observations from July 2016. As the glacier approaches a potential period of rapid terminal retreat, this data gives refined physical information prior to this potential juncture in the tidewater cycle-an observation that may yield insight into marine ice sheet instabilities more broadly.

The chemical biology of methanogenesis

NASA Astrophysics Data System (ADS)

Ferry, James G.

2010-12-01

Two distinct pathways account for most of the CH 4 produced in the majority of the diverse and vast anaerobic environments of Earth's biosphere by microbes that are classified in the Archaea domain of life: conversion of the methyl group of acetate to CH 4 in the aceticlastic pathway and reduction of CO 2 with electrons derived from H 2, formate or CO in the CO 2 reduction pathway. Minor, albeit ecologically important, amounts of CH 4 are produced by conversion of methylotrophic substrates methanol, methylamines and methyl sulfides. Although all pathways have terminal steps in common, they deviate in the initial steps leading to CH 4 and mechanisms for synthesizing ATP for growth. Hydrogen gas is the major reductant for CO 2-reducing methanogens in the deep subsurface, although H 2 is also utilized by CO 2-reducing microbes from the Bacteria domain that produce acetate for the aceticlastic methanogens. This review presents fundamentals of the two major CH 4-producing pathways with a focus on understanding the potential for biologically-produced CH 4 on Mars.

An integrated environmental tracer approach to characterizing groundwater circulation in a mountain block

USGS Publications Warehouse

Manning, Andrew H.; Solomon, D. Kip

2005-01-01

The subsurface transfer of water from a mountain block to an adjacent basin (mountain block recharge (MBR)) is a commonly invoked mechanism of recharge to intermountain basins. However, MBR estimates are highly uncertain. We present an approach to characterize bulk fluid circulation in a mountain block and thus MBR that utilizes environmental tracers from the basin aquifer. Noble gas recharge temperatures, groundwater ages, and temperature data combined with heat and fluid flow modeling are used to identify clearly improbable flow regimes in the southeastern Salt Lake Valley, Utah, and adjacent Wasatch Mountains. The range of possible MBR rates is reduced by 70%. Derived MBR rates (5.5–12.6 × 104 m3 d−1) are on the same order of magnitude as previous large estimates, indicating that significant MBR to intermountain basins is plausible. However, derived rates are 50–100% of the lowest previous estimate, meaning total recharge is probably less than previously thought.

Microstructure and Tribological Properties of Mo-40Ni-13Si Multiphase Intermetallic Alloy.

PubMed

Song, Chunyan; Wang, Shuhuan; Gui, Yongliang; Cheng, Zihao; Ni, Guolong

2016-12-06

Intermetallic compounds are increasingly being expected to be utilized in tribological environments, but to date their implementation is hindered by insufficient ductility at low and medium temperatures. This paper presents a novel multiphase intermetallic alloy with the chemical composition of Mo-40Ni-13Si (at %). Microstructure characterization reveals that a certain amount of ductile Mo phases formed during the solidification process of a ternary Mo-Ni-Si molten alloy, which is beneficial to the improvement of ductility of intermetallic alloys. Tribological properties of the designed alloy-including wear resistance, friction coefficient, and metallic tribological compatibility-were evaluated under dry sliding wear test conditions at room temperature. Results suggest that the multiphase alloy possesses an excellent tribological property, which is attributed to unique microstructural features and thereby a good combination in hardness and ductility. The corresponding wear mechanism is explained by observing the worn surface, subsurface, and wear debris of the alloy, which was found to be soft abrasive wear.

Fundamental phenomena on fuel decomposition and boundary-layer combustion processes with applications to hybrid rocket motors

NASA Technical Reports Server (NTRS)

Kuo, Kenneth K.; Lu, Yeu-Cherng; Chiaverini, Martin J.; Harting, George C.; Johnson, David K.; Serin, Nadir

1995-01-01

The experimental study on the fundamental processes involved in fuel decomposition and boundary-layer combustion in hybrid rocket motors is continuously being conducted at the High Pressure Combustion Laboratory of The Pennsylvania State University. This research will provide a useful engineering technology base in the development of hybrid rocket motors as well as a fundamental understanding of the complex processes involved in hybrid propulsion. A high-pressure, 2-D slab motor has been designed, manufactured, and utilized for conducting seven test firings using HTPB fuel processed at PSU. A total of 20 fuel slabs have been received from the Mcdonnell Douglas Aerospace Corporation. Ten of these fuel slabs contain an array of fine-wire thermocouples for measuring solid fuel surface and subsurface temperatures. Diagnostic instrumentation used in the test include high-frequency pressure transducers for measuring static and dynamic motor pressures and fine-wire thermocouples for measuring solid fuel surface and subsurface temperatures. The ultrasonic pulse-echo technique as well as a real-time x-ray radiography system have been used to obtain independent measurements of instantaneous solid fuel regression rates.

dfnWorks: A discrete fracture network framework for modeling subsurface flow and transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia

DFNWORKS is a parallelized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using DFNGEN, which combines FRAM (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs with the LaGriT meshing toolbox to create a high-quality computational mesh representation. The representation produces a conforming Delaunay triangulation suitable for high performance computing finite volume solvers in anmore » intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code PFLOTRAN. A Lagrangian approach to simulating transport through the DFN is adopted within DFNTRANS to determine pathlines and solute transport through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO 2 sequestration are also included.« less

Nondestructive evaluation of structural ceramics by photoacoustic microscopy

NASA Technical Reports Server (NTRS)

Khandelwal, Pramod K.

1987-01-01

A photoacoustic microscopy (PAM) digital imaging system was developed and utilized to characterize silicon nitride material at the various stages of the ceramic fabrication process. Correlation studies revealed that photoacoustic microscopy detected failure initiating defects in substantially more specimens than microradiography and ultrasonic techniques. Photoacoustic microscopy detected 10 to 100 micron size surface and subsurface pores and inclusions, respectively, up to 80 microns below the interrogating surface in machined sintered silicon nitride. Microradiography detected 50 micron diameter fracture controlling pores and inclusions. Subsurface holes were detected up to a depth of 570 microns and 1.00 mm in sintered silicon nitride and silicon carbide, respectively. Seeded voids of 20 to 30 micron diameters at the surface and 50 microns below the interrogating surface were detected by photoacoustic microscopy and microradiography with 1 percent X-ray thickness sensitivity. Tight surface cracks of 96 micron length x 48 micron depth were detected by photoacoustic microscopy. PAM volatilized and removed material in the green state which resulted in linear shallow microcracks after sintering. This significantly limits the use of PAM as an in-process NDE technique.

Fundamental phenomena on fuel decomposition and boundary-layer combustion processes with applications to hybrid rocket motors

NASA Astrophysics Data System (ADS)

Kuo, Kenneth K.; Lu, Yeu-Cherng; Chiaverini, Martin J.; Harting, George C.; Johnson, David K.; Serin, Nadir

The experimental study on the fundamental processes involved in fuel decomposition and boundary-layer combustion in hybrid rocket motors is continuously being conducted at the High Pressure Combustion Laboratory of The Pennsylvania State University. This research will provide a useful engineering technology base in the development of hybrid rocket motors as well as a fundamental understanding of the complex processes involved in hybrid propulsion. A high-pressure, 2-D slab motor has been designed, manufactured, and utilized for conducting seven test firings using HTPB fuel processed at PSU. A total of 20 fuel slabs have been received from the Mcdonnell Douglas Aerospace Corporation. Ten of these fuel slabs contain an array of fine-wire thermocouples for measuring solid fuel surface and subsurface temperatures. Diagnostic instrumentation used in the test include high-frequency pressure transducers for measuring static and dynamic motor pressures and fine-wire thermocouples for measuring solid fuel surface and subsurface temperatures. The ultrasonic pulse-echo technique as well as a real-time x-ray radiography system have been used to obtain independent measurements of instantaneous solid fuel regression rates.

dfnWorks: A discrete fracture network framework for modeling subsurface flow and transport

DOE PAGES

Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; ...

2015-11-01

DFNWORKS is a parallelized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using DFNGEN, which combines FRAM (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs with the LaGriT meshing toolbox to create a high-quality computational mesh representation. The representation produces a conforming Delaunay triangulation suitable for high performance computing finite volume solvers in anmore » intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code PFLOTRAN. A Lagrangian approach to simulating transport through the DFN is adopted within DFNTRANS to determine pathlines and solute transport through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO 2 sequestration are also included.« less

Analytical solutions for efficient interpretation of single-well push-pull tracer tests

NASA Astrophysics Data System (ADS)

Huang, Junqi; Christ, John A.; Goltz, Mark N.

2010-08-01

Single-well push-pull tracer tests have been used to characterize the extent, fate, and transport of subsurface contamination. Analytical solutions provide one alternative for interpreting test results. In this work, an exact analytical solution to two-dimensional equations describing the governing processes acting on a dissolved compound during a modified push-pull test (advection, longitudinal and transverse dispersion, first-order decay, and rate-limited sorption/partitioning in steady, divergent, and convergent flow fields) is developed. The coupling of this solution with inverse modeling to estimate aquifer parameters provides an efficient methodology for subsurface characterization. Synthetic data for single-well push-pull tests are employed to demonstrate the utility of the solution for determining (1) estimates of aquifer longitudinal and transverse dispersivities, (2) sorption distribution coefficients and rate constants, and (3) non-aqueous phase liquid (NAPL) saturations. Employment of the solution to estimate NAPL saturations based on partitioning and non-partitioning tracers is designed to overcome limitations of previous efforts by including rate-limited mass transfer. This solution provides a new tool for use by practitioners when interpreting single-well push-pull test results.

A reactive transport model for Marcellus shale weathering

NASA Astrophysics Data System (ADS)

Heidari, Peyman; Li, Li; Jin, Lixin; Williams, Jennifer Z.; Brantley, Susan L.

2017-11-01

Shale formations account for 25% of the land surface globally and contribute a large proportion of the natural gas used in the United States. One of the most productive shale-gas formations is the Marcellus, a black shale that is rich in organic matter and pyrite. As a first step toward understanding how Marcellus shale interacts with water in the surface or deep subsurface, we developed a reactive transport model to simulate shale weathering under ambient temperature and pressure conditions, constrained by soil and water chemistry data. The simulation was carried out for 10,000 years since deglaciation, assuming bedrock weathering and soil genesis began after the last glacial maximum. Results indicate weathering was initiated by pyrite dissolution for the first 1000 years, leading to low pH and enhanced dissolution of chlorite and precipitation of iron hydroxides. After pyrite depletion, chlorite dissolved slowly, primarily facilitated by the presence of CO2 and organic acids, forming vermiculite as a secondary mineral. A sensitivity analysis indicated that the most important controls on weathering include the presence of reactive gases (CO2 and O2), specific surface area, and flow velocity of infiltrating meteoric water. The soil chemistry and mineralogy data could not be reproduced without including the reactive gases. For example, pyrite remained in the soil even after 10,000 years if O2 was not continuously present in the soil column; likewise, chlorite remained abundant and porosity remained small if CO2 was not present in the soil gas. The field observations were only simulated successfully when the modeled specific surface areas of the reactive minerals were 1-3 orders of magnitude smaller than surface area values measured for powdered minerals. Small surface areas could be consistent with the lack of accessibility of some fluids to mineral surfaces due to surface coatings. In addition, some mineral surface is likely interacting only with equilibrated pore fluids. An increase in the water infiltration rate enhanced weathering by removing dissolution products and maintaining far-from-equilibrium conditions. We conclude from these observations that availability of reactive surface area and transport of H2O and gases are the most important factors affecting rates of Marcellus shale weathering of the in the shallow subsurface. This weathering study documents the utility of reactive transport modeling for complex subsurface processes. Such modelling could be extended to understand interactions between injected fluids and Marcellus shale gas reservoirs at higher temperature, pressure, and salinity conditions.

Waves of the Future (for Mars): In-Situ Mid-infrared, Near-infrared, and Visible Spectroscopic Analysis of Antarctic Cryptoendolithic Communities.

NASA Astrophysics Data System (ADS)

Hand, K. P.; Calrson, R.; Sun, H.; Anderson, M.; Wynn, W.; Levy, R.

2005-12-01

We have analyzed both the surface expression and depth profile of cryptoendolithic microbial communities at Battleship Promontory, in the Dry Valleys of Antarctica. Data was collected on site with an active mid-infrared Fourier transform microspectrometer (2.6 - 15 um), a near-infrared spectrometer (0.9-1.8 um), and a visible spectrometer (0.4-1 um). The trio of instruments are connected to microscopes that yield ~1 mm2 spatial resolution on the sample and they are mounted on two perpendicular motorized stages that allow for spatial scanning over an area of ~2cm2. Here we present results on the surface expression of the subsurface microbes in these three spectral regions and we present results on the analysis of a colonized sample examined in cross section. The former case has direct application to the remote, robotic detection of life within the rocks of Mars and the later case provides fundamental insights into the geological and biological interactions that make the Antarctic cryptoendolithic ecosystems possible. Non-invasive surface detection of cyanobacterial dominated communities was possible through the observation of several distinct bands: the carbon-hydrogen stretching modes (symmetric and asymmetric) for CH, CH2, and CH3 in the regions of 3.3-3.6 um and 3.6-3.7 um; the NH2 scissoring and C=O stretch near 6.0 um; the amide I of beta-pleated structures at ~6.1 um; and the 6.4 um - 6.6 um bands of N-H in plane bend of the amide II functional group. In combination, these bands make a strong case for carbohydrates and proteins associated with life. Not surprisingly, as the integrity of the amorphous silica surface varnish improved, our ability to detected the subsurface biosignature decreased. We note, however, that by utilizing the JPL rock crusher in Antarctica, a device designed to fly on the Mars Science Laboratory mission, the mid-infrared biosignature was easily detected. In the cross-section analysis the mid-infrared data provide a depth profile tracking the presence of hydrocarbons, amide bonds, and the mineralogical transition from amorphous quartz to crystalline sandstone. Mapped onto this are the changes in the oxidation states of iron, as recorded by the visible and near-infrared spectrometers. Together, this data set allows us to track the role of biologically produced compounds, such as oxalic acid, in the chelation and leaching of iron compounds from the surface through the rock and into the deposition zone below the colonized subsurface region.

Survivability and growth kinetics of methanogenic archaea at various pHs and pressures: Implications for deep subsurface life on Mars

NASA Astrophysics Data System (ADS)

Sinha, Navita; Nepal, Sudip; Kral, Timothy; Kumar, Pradeep

2017-02-01

Life as we know it requires liquid water and sufficient liquid water is highly unlikely on the surface of present-day Mars. However, according to thermal models there is a possibility of liquid water in the deep subsurface of Mars. Thus, the martian subsurface, where the pressure and temperature is higher, could potentially provide a hospitable environment for a biosphere. Also, methane has been detected in the Mars' atmosphere. Analogous to Earth's atmospheric methane, martian methane could also be biological in origin. The carbon and energy sources for methanogenesis in the subsurface of Mars could be available by downwelling of atmospheric CO2 into the regolith and water-rock reactions such as serpentinization, respectively. Corresponding analogs of the martian subsurface on Earth might be the active sites of serpentinization at depths where methanogenic thermophilic archaea are the dominant species. Methanogens residing in Earth's hydrothermal environments are usually exposed to a variety of physiological stresses including a wide range of pressures, temperatures, and pHs. Martian geochemical models imply that the pH of probable groundwater varies from 4.96 to 9.13. In this work, we used the thermophilic methanogen, Methanothermobacter wolfeii, which grows optimally at 55oC. Therefore, a temperature of 55oC was chosen for these experiments, possibly simulating Mars' subsurface temperature. A martian geophysical model suggests depth and pressure corresponding to a temperature of 55 °C would be between 1-30 km and 100-3,000 atm respectively. Here, we have simulated Mars deep subsurface pH, pressure, and temperature conditions and have investigated the survivability, growth rate, and morphology of M. wolfeii after exposure to a wide range of pH 5-9) and pressure (1-1200 atm) at a temperature of 55 °C. Interestingly, in this study we have found that M. wolfeii was able to survive at all the pressures and pHs tested at 55 °C. In order to understand the effect of different pHs and pressures on the metabolic activities of M. wolfeii, we also calculated their growth rate by measuring methane concentration in the headspace gas samples at regular intervals. In acidic conditions, the growth rate (γ) of M. wolfeii increased with the increase in pressure. In neutral and alkaline conditions, the growth rate (γ) of M. wolfeii initially increased with pressure, but decreased upon further increase of pressure. To investigate the effect of combined pH, pressure, and temperature on the morphology of M. wolfeii, we took phase contrast images of the cells. We did not find any obvious significant alteration in the morphology of M. wolfeii cells. Methanogens, chemolithoautotrophic anaerobic microorganisms, are considered as ideal model microorganisms for Mars. In light of research presented here, we suggest that at least one methanogen, M. wolfeii, could survive in the deep subsurface environment of Mars.

Reconstruction of paleoenvironmental changes based on the planktonic foraminiferal assemblages off Shimokita (Japan) in the northwestern North Pacific

NASA Astrophysics Data System (ADS)

Kuroyanagi, Azumi; Kawahata, Hodaka; Narita, Hisashi; Ohkushi, Ken'ichi; Aramaki, Takafumi

2006-08-01

Planktonic foraminifera live in the upper ocean, and their assemblages can record the surrounding environment. To reconstruct changes in water masses and the timing of flow of the Oyashio and Tsugaru currents through the Tsugaru Strait after the Last Glacial Maximum, when the Japan Sea had been almost isolated from the surrounding seas, we investigated at high resolution the planktonic foraminiferal fauna in seafloor sediments off the Shimokita (core MD01-2409: 41°33.9'N, 141°52.1'E), in the northwestern North Pacific, over the last 26,900 years. Factor analysis of the foraminiferal assemblage suggests that the water mass changed significantly as a result of the deglacial sea-level rise and opening of the straits into the Japan Sea. Mass accumulation rates of some selected foraminiferal species that inhabit characteristic environments (e.g., warm stratified water, Oyashio Current, Tsushima Current) corroborate these changes in water mass and water column structure. We also used the ratio of the dextral form to total Neogloboquadrina pachyderma as an indicator of subsurface (below the pycnocline) water temperature. We recognized five distinct periods of oceanographic change at the study site, which is just east of the Tsugaru Strait: (1) Oyashio Current affecting both surface and subsurface waters (26.9-15.7 thousand calendar years before present (cal. kyr BP)); (2) vertical mixing and subsurface warming as the Oyashio Current began to flow into the Japan Sea through the Tsugaru Strait (15.7-10.6 cal. kyr BP); (3) outflow of the Tsugaru Current from the Japan Sea into the Pacific, leading to baroclinic conditions, with the surface layer under the influence of the Tsugaru and the subsurface layers of the Oyashio Current (10.6-9.0 cal. kyr BP); (4) stratification of the water column developed as the flow of the Tsugaru Current increased (9.0-6.2 cal. kyr BP); and (5) warming of the subsurface layer, disruption of the stratification, and dominance of the Tsugaru Current in both surface and subsurface layers, similar to the present situation (6.2-1.5 cal. kyr BP). The timing of flow of the Oyashio and Tsugaru currents through the strait at the study site off Shimokita is generally compatible with the results of studies in the Japan Sea. The flow of the Tsugaru Current led to progressive warming of the waters, from the surface to the subsurface layers and from the Japan Sea side to the Pacific side of the Tsugaru Strait, beginning in 8.3-6.8 cal. kyr BP on the western side, and in 6.2 cal. kyr BP on the eastern side of the strait. By 4.8 cal. kyr BP on the western side, and by ˜ 3.4 cal. kyr BP on the eastern side of the strait, warm water prevailed in both surface and subsurface layers.

Subsurface Feature Mapping of Mars using a High Resolution Ground Penetrating Radar System

NASA Astrophysics Data System (ADS)

Wu, T. S.; Persaud, D. M.; Preudhomme, M. A.; Jurg, M.; Smith, M. K.; Buckley, H.; Tarnas, J.; Chalumeau, C.; Lombard-Poirot, N.; Mann, B.

2015-12-01

As the closest Earth-like, potentially life-sustaining planet in the solar system, Mars' future of human exploration is more a question of timing than possibility. The Martian surface remains hostile, but its subsurface geology holds promise for present or ancient astrobiology and future habitation, specifically lava tube (pyroduct) systems, whose presence has been confirmed by HiRISE imagery.The location and characterization of these systems could provide a basis for understanding the evolution of the red planet and long-term shelters for future manned missions on Mars. To detect and analyze the subsurface geology of terrestrial bodies from orbit, a novel compact (smallsat-scale) and cost-effective approach called the High-resolution Orbiter for Mapping gEology by Radar (HOMER) has been proposed. Adapting interferometry techniques with synthetic aperture radar (SAR) to a ground penetrating radar system, a small satellite constellation is able to achieve a theoretical resolution of 50m from low-Mars orbit (LMO). Alongside this initial prototype design of HOMER, proposed data processing methodology and software and a Mars mission design are presented. This project was developed as part of the 2015 NASA Ames Academy for Space Exploration.

Sorption of Pseudomonas putida onto differently structured kaolinite minerals

NASA Astrophysics Data System (ADS)

Vasiliadou, I. A.; Papoulis, D.; Chrysikopoulos, C.; Panagiotaras, D.; Karakosta, E.; Fardis, M.; Papavassiliou, G.

2010-12-01

The presence of bio-colloids (e.g. bacteria and viruses) in the subsurface could be attributed to the release of particles from septic tanks, broken sewer lines or from artificial recharge with treated municipal wastewater. Bio-colloid transport in the subsurface is significantly affected by sorption onto the solid matrix. Bio-colloid attachment onto mobile or suspended in the aqueous phase soil particles (e.g. clay or other minerals) also may influence their fate and transport in the subsurface. The present study focuses on the investigation of Pseudomonas (Ps.) putida sorption onto well (KGa-1) and poorly (KGa-2) crystallized kaolinite minerals. Batch experiments were carried out to determine the sorption isotherms of Ps. putida onto both types of kaolinite particles. The sorption process of Ps. putida onto KGa-1 and KGa-2 is adequately described by a Langmuir isotherm. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy as well as Nuclear Magnetic Resonance were employed to study the sorption mechanisms of Ps. putida. Experimental results indicated that KGa-2 presented higher affinity and sorption capacity than KGa-1. It was shown that electrostatic interactions and structural disorders can influence the sorption capacity of clay particles.

Predictive assimilation framework to support contaminated site understanding and remediation

NASA Astrophysics Data System (ADS)

Versteeg, R. J.; Bianchi, M.; Hubbard, S. S.

2014-12-01

Subsurface system behavior at contaminated sites is driven and controlled by the interplay of physical, chemical, and biological processes occurring at multiple temporal and spatial scales. Effective remediation and monitoring planning requires an understanding of this complexity that is current, predictive (with some level of confidence) and actionable. We present and demonstrate a predictive assimilation framework (PAF). This framework automatically ingests, quality controls and stores near real-time environmental data and processes these data using different inversion and modeling codes to provide information on the current state and evolution of the subsurface system. PAF is implemented as a cloud based software application which has five components: (1) data acquisition, (2) data management, (3) data assimilation and processing, (4) visualization and result deliver and (5) orchestration. Access to and interaction with PAF is done through a standard browser. PAF is designed to be modular so that it can ingest and process different data streams dependent on the site. We will present an implementation of PAF which uses data from a highly instrumented site (the DOE Rifle Subsurface Biogeochemistry Field Observatory in Rifle, Colorado) for which PAF automatically ingests hydrological data and forward models groundwater flow in the saturated zone.

Characterizing the deformation of reservoirs using interferometry, gravity, and seismic analyses

NASA Astrophysics Data System (ADS)

Schiek, Cara Gina

In this dissertation, I characterize how reservoirs deform using surface and subsurface techniques. The surface technique I employ is radar interferometry, also known as InSAR (Interferometric Synthetic Aperture Radar). The subsurface analyses I explore include gravity modeling and seismic techniques consisting of determining earthquake locations from a small-temporary seismic network of six seismometers. These techniques were used in two different projects to determine how reservoirs deform in the subsurface and how this deformation relates to its remotely sensed surface deformation. The first project uses InSAR to determine land subsidence in the Mimbres basin near Deming, NM. The land subsidence measurements are visually compared to gravity models in order to determine the influence of near surface faults on the subsidence and the physical properties of the aquifers in these basins. Elastic storage coefficients were calculated for the Mimbres basin to aid in determining the stress regime of the aquifers. In the Mimbres basin, I determine that it is experiencing elastic deformation at differing compaction rates. The west side of the Mimbres basin is deforming faster, 17 mm/yr, while the east side of the basin is compacting at a rate of 11 mm/yr. The second project focuses on San Miguel volcano, El Salvador. Here, I integrate InSAR with earthquake locations using surface deformation forward modeling to investigate the explosive volcanism in this region. This investigation determined the areas around the volcano that are undergoing deformation, and that could lead to volcanic hazards such as slope failure from a fractured volcano interior. I use the earthquake epicenters with field data to define the subsurface geometry of the deformation source, which I forward model to produce synthetic interferograms. Residuals between the synthetic and observed interferograms demonstrate that the observed deformation is a direct result of the seismic activity along the San Miguel Fracture Zone. Based on the large number of earthquakes concentrated in this region and the fracturing suggested by the earthquake location results, I conclude that the southwestern slope of San Miguel is the most susceptible to volcanic hazards such as landsliding and flank lava flows. Together these projects explore the dynamics of reservoir systems, both hydrologic and magmatic. They show the utility of geodetic remote sensing to constrain the relative importance of various, complex, subsurface processes, including faulting, fluid migration, and compaction.

A porewater - based stable isotope approach for the investigation of subsurface hydrological processes

NASA Astrophysics Data System (ADS)

Garvelmann, J.; Külls, C.; Weiler, M.

2011-10-01

Predicting and understanding subsurface flowpaths is still a crucial issue in hydrological research. We present an experimental approach to reveal present and past subsurface flowpaths of water in the unsaturated and saturated zone. Two hillslopes in a humid moutainous catchment have been investigated. The H2O(liquid) - H2O(vapor) equilibration laser spectroscopy method was used to obtain high resolution δ2H vertical depth profiles of porewater at various points along a fall line of a pasture hillslope in the southern Black Forest, Germany. The Porewater Stable Isotope Profile (PSIP) approach was developed to use the integrated information of several vertical depth profiles of deuterium along two transects at the hillslopes. Different shapes of depth profiles were observed in relation to hillslope position. The statistical variability (inter-quartile range and standard deviation) of each profile was used to characterize different types of depth profiles. The profiles upslope or with a weak affinity for saturation as indicated by a low topographic wetness index preserve the isotopic input signal by precipitation with a distinct seasonal variability. These observations indicate mainly vertical movement of soil water in the upper part of the hillslope before sampling. The profiles downslope or at locations with a strong affinity for saturation do not show a similar seasonal isotopic signal. The input signal is erased in the foothills and a large proportion of pore water samples are close to the isotopic values of δ2H in stream water during base flow. Near the stream indications for efficient mixing of water from lateral subsurface flow paths with vertical percolation are found.

Experimental validation of a sub-surface model of solar power for distributed marine sensor systems

NASA Astrophysics Data System (ADS)

Hahn, Gregory G.; Cantin, Heather P.; Shafer, Michael W.

2016-04-01

The capabilities of distributed sensor systems such as marine wildlife telemetry tags could be significantly enhanced through the integration of photovoltaic modules. Photovoltaic cells could be used to supplement the primary batteries for wildlife telemetry tags to allow for extended tag deployments, wherein larger amounts of data could be collected and transmitted in near real time. In this article, we present experimental results used to validate and improve key aspects of our original model for sub-surface solar power. We discuss the test methods and results, comparing analytic predictions to experimental results. In a previous work, we introduced a model for sub-surface solar power that used analytic models and empirical data to predict the solar irradiance available for harvest at any depth under the ocean's surface over the course of a year. This model presented underwater photovoltaic transduction as a viable means of supplementing energy for marine wildlife telemetry tags. The additional data provided by improvements in daily energy budgets would enhance the temporal and spatial comprehension of the host's activities and/or environments. Photovoltaic transduction is one method that has not been widely deployed in the sub-surface marine environments despite widespread use on terrestrial and avian species wildlife tag systems. Until now, the use of photovoltaic cells for underwater energy harvesting has generally been disregarded as a viable energy source in this arena. In addition to marine telemetry systems, photovoltaic energy harvesting systems could also serve as a means of energy supply for autonomous underwater vehicles (AUVs), as well as submersible buoys for oceanographic data collection.

Trace Element and Cu Isotopic Tracers of Subsurface Flow and Transport in Wastewater Irrigated Soils

NASA Astrophysics Data System (ADS)

Carte, J.; Fantle, M. S.

2017-12-01

An understanding of subsurface flow paths is critical for quantifying the fate of contaminants in wastewater irrigation systems. This study investigates the subsurface flow of wastewater by quantifying the distribution of trace contaminants in wastewater irrigated soils. Soil samples were collected from the upper 1m of two wetlands at Penn State University's wastewater irrigation site, at which all effluent from the University's wastewater treatment plant has been sprayed since 1983. Major and trace element and Cu isotopic composition were determined for these samples, in addition to wastewater effluent and bedrock samples. The upper 20 cm of each wetland shows an enrichment of Bi, Cd, Cr, Cu, Mo, Ni, Pb, and Zn concentrations relative to deep (>1m) soils at the site by a factor of 1.7-3.5. Each wetland also has a subsurface clay rich horizon with Bi, Cu, Li, Ni, Pb, and Zn concentrations enriched by a factor of 1.4 to 5 relative to deep soils. These subsurface horizons directly underlie intervals that could facilitate preferential effluent flow: a gravel layer in one wetland, and a silty loam with visible mottling, an indication of dynamic water saturation, in the other. Trace metal concentrations in other horizons from both wetlands fall in the range of the deep soils. Significant variability in Cu isotopic composition is present in soils from both wetlands, with δ65Cu values ranging from 0.74‰ to 5.09‰. Soil δ65Cu correlates well with Cu concentrations, with lighter δ65Cu associated with higher concentrations. The Cu isotopic composition of the zones of metal enrichment are comparable to the ostensible average wastewater effluent δ65Cu value (0.61‰), while other horizons have considerably heavier δ65Cu values. We hypothesize that wastewater is the source of the metal enrichments, as each of the enriched elements are present as contaminants in wastewater, and the enrichments are located in clay-rich horizons conducive to trace metal immobilization due to adsorption. This hypothesis will be further tested by modeling with the reactive transport code CrunchTope. This study provides evidence that trace element and isotopic composition of soils can be useful tracers of subsurface hydrologic pathways and elemental fate and transport.

Extending RTM Imaging With a Focus on Head Waves

NASA Astrophysics Data System (ADS)

Holicki, Max; Drijkoningen, Guy

2016-04-01

Conventional industry seismic imaging predominantly focuses on pre-critical reflections, muting post-critical arrivals in the process. This standard approach neglects a lot of information present in the recorded wave field. This negligence has been partially remedied with the inclusion of head waves in more advanced imaging techniques, like Full Waveform Inversion (FWI). We would like to see post-critical information leave the realm of labour-intensive travel-time picking and tomographic inversion towards full migration to improve subsurface imaging and parameter estimation. We present a novel seismic imaging approach aimed at exploiting post-critical information, using the constant travel path for head-waves between shots. To this end, we propose to generalize conventional Reverse Time Migration (RTM) to scenarios where the sources for the forward and backward propagated wave-fields are not coinciding. RTM functions on the principle that backward propagated receiver data, due to a source at some locations, must overlap with the forward propagated source wave field, from the same source location, at subsurface scatterers. Where the wave-fields overlap in the subsurface there is a peak at the zero-lag cross-correlation, and this peak is used for the imaging. For the inclusion of head waves, we propose to relax the condition of coincident sources. This means that wave-fields, from non-coincident-sources, will not overlap properly in the subsurface anymore. We can make the wave-fields overlap in the subsurface again, by time shifting either the forward or backward propagated wave-fields until the wave-fields overlap. This is the same as imaging at non-zero cross-correlation lags, where the lag is the travel time difference between the two wave-fields for a given event. This allows us to steer which arrivals we would like to use for imaging. In the simplest case we could use Eikonal travel-times to generate our migration image, or we exclusively image the subsurface with the head wave from the nth-layer. To illustrate the method we apply it to a layered Earth model with five layers and compare it to conventional RTM. We will show that conventional RTM highlights interfaces, while our head-wave based images highlight layers, producing fundamentally different images. We also demonstrate that our proposed imaging scheme is more sensitive to the velocity model than conventional RTM, which is important for improved velocity model building in the future.

The Development of 3d Sub-Surface Mapping Scheme and its Application to Martian Lobate Debris Aprons

NASA Astrophysics Data System (ADS)

Baik, H.; Kim, J.

2017-07-01

The Shallow Subsurface Radar (SHARAD), a sounding radar equipped on the Mars Reconnaissance Orbiter (MRO), has produced highly valuable information about the Martian subsurface. In particular, the complicated substructures of Mars such as polar deposit, pedestal crater and the other geomorphic features involving possible subsurface ice body has been successfully investigated by SHARAD. In this study, we established a 3D subsurface mapping strategy employing the multiple SHARAD profiles. A number of interpretation components of SHARAD signals were integrated into a subsurface mapping scheme using radargram information and topographic data, then applied over a few mid latitude Lobate Debris Aprons (LDAs). From the identified subsurface layers of LDA, and the GIS data base incorporating the other interpretation outcomes, we are expecting to trace the origin of LDAs. Also, the subsurface mapping scheme developed in this study will be further applied to other interesting Martian geological features such as inter crater structures, aeolian deposits and fluvial sediments. To achieve higher precision sub-surface mapping, the clutter simulation employing the high resolution topographic data and the upgraded clustering algorithms assuming multiple sub-surface layers will be also developed.

Nature of a cone-shaped subsurface feature below a large seafloor depression on the Chatham Rise, New Zealand

NASA Astrophysics Data System (ADS)

Waghorn, K. A.; Pecher, I. A.; Strachan, L. J.; Crutchley, G.; Coffin, R. B.; Rose, P. S.; Bialas, J.; Davy, B. W.; Kroeger, K.

2013-12-01

An area of extensive seafloor depressions occurs on the Southern Chatham Rise, New Zealand. The 2013 R/V Sonne SO-226 voyage aimed to investigate the formation and occurrences of these features and their possible relation to release of gas during glacial-interglacial cycles. The seafloor depressions occur in water depths of 500-1100m. This presentation focuses on a depression with a diameter of approximately 1km in a water depth of ~1000m. We present initial results from a high-resolution subsurface 3D seismic data cube collected across the seafloor depression. The data were collected using the P-Cable system, which has been developed specifically for imaging the shallow subsurface. The data shows an enigmatic conical-shaped feature underlying the seafloor depression with an area surrounding which has been initially interpreted as a giant gas chimney flow-zone. While geochemical results indicate no present day methane flux, the geophysical data shows a presence of blanking which may be associated with gas or gas hydrate close to the seafloor. We show first interpretations of the nature of this feature and its emplacement. Our preferred causes are either a volcanic cone or a mud diapir. We speculate that emplacement of this feature has been instrumental in forming the overlying seafloor depressions but are still evaluating the potential linkages.

Design Of Bioremediation Systems For Groundwater (Aerobic and Anaerobic Plus Representative Case Studies)

EPA Science Inventory

The attached presentation discusses the fundamentals of bioremediation in the subsurface. The basics of aerobic, cometabolic, and anaerobic bioremediation are presented. Case studies from the Delaware Sand & Gravel Superfund Site, Dover Cometabolic Research Project and the SABR...

Shocking Path of Least Resistance Shines Light on Subsurface by Revealing the Paths of Water and the Presence of Faults: Stacked EM Case Studies over Barite Hills Superfund Site in South Carolina

NASA Astrophysics Data System (ADS)

Haggar, K. S.; Nelson, H. R., Jr.; Berent, L. J.

2017-12-01

The Barite Hills/Nevada Gold Fields mines are in Late Proterozoic and early Paleozoic rocks of the gold and iron sulfides rich Carolina slate belt. The mines were active from 1989 to1995. EPA and USGS site investigations in 2003 resulted in the declaration of the waste pit areas as a superfund site. The USGS and private consulting firms have evaluated subsurface water flow paths, faults & other groundwater-related features at this superfund site utilizing 2-D conductivity & 3-D electromagnetic (EM) surveys. The USGS employed conductivity to generate instantaneous 2-D profiles to evaluate shallow groundwater patterns. Porous regolith sediments, contaminated water & mine debris have high conductivity whereas bedrock is identified by its characteristic low conductivity readings. Consulting contractors integrated EM technology, magnetic & shallow well data to generate 3-D images of groundwater flow paths at given depths across the superfund site. In so doing several previously undetected faults were identified. Lighting strike data was integrated with the previously evaluated electrical and EM data to determine whether this form of natural-sourced EM data could complement and supplement the more traditional geophysical data described above. Several lightning attributes derived from 3-D lightning volumes were found to correlate to various features identified in the previous geophysical studies. Specifically, the attributes Apparent Resistivity, Apparent Permittivity, Peak Current & Tidal Gravity provided the deepest structural geological framework & provided insights into rock properties & earth tides. Most significantly, Peak Current showed remarkable coincidence with the preferred groundwater flow map identified by one of the contractors utilizing EM technology. This study demonstrates the utility of robust integrated EM technology applications for projects focused on hydrology, geohazards to dams, levees, and structures, as well as mineral and hydrocarbon exploration.

Comparative Single-Cell Genomics of Chloroflexi from the Okinawa Trough Deep-Subsurface Biosphere.

PubMed

Fullerton, Heather; Moyer, Craig L

2016-05-15

Chloroflexi small-subunit (SSU) rRNA gene sequences are frequently recovered from subseafloor environments, but the metabolic potential of the phylum is poorly understood. The phylum Chloroflexi is represented by isolates with diverse metabolic strategies, including anoxic phototrophy, fermentation, and reductive dehalogenation; therefore, function cannot be attributed to these organisms based solely on phylogeny. Single-cell genomics can provide metabolic insights into uncultured organisms, like the deep-subsurface Chloroflexi Nine SSU rRNA gene sequences were identified from single-cell sorts of whole-round core material collected from the Okinawa Trough at Iheya North hydrothermal field as part of Integrated Ocean Drilling Program (IODP) expedition 331 (Deep Hot Biosphere). Previous studies of subsurface Chloroflexi single amplified genomes (SAGs) suggested heterotrophic or lithotrophic metabolisms and provided no evidence for growth by reductive dehalogenation. Our nine Chloroflexi SAGs (seven of which are from the order Anaerolineales) indicate that, in addition to genes for the Wood-Ljungdahl pathway, exogenous carbon sources can be actively transported into cells. At least one subunit for pyruvate ferredoxin oxidoreductase was found in four of the Chloroflexi SAGs. This protein can provide a link between the Wood-Ljungdahl pathway and other carbon anabolic pathways. Finally, one of the seven Anaerolineales SAGs contains a distinct reductive dehalogenase homologous (rdhA) gene. Through the use of single amplified genomes (SAGs), we have extended the metabolic potential of an understudied group of subsurface microbes, the Chloroflexi These microbes are frequently detected in the subsurface biosphere, though their metabolic capabilities have remained elusive. In contrast to previously examined Chloroflexi SAGs, our genomes (several are from the order Anaerolineales) were recovered from a hydrothermally driven system and therefore provide a unique window into the metabolic potential of this type of habitat. In addition, a reductive dehalogenase gene (rdhA) has been directly linked to marine subsurface Chloroflexi, suggesting that reductive dehalogenation is not limited to the class Dehalococcoidia This discovery expands the nutrient-cycling and metabolic potential present within the deep subsurface and provides functional gene information relating to this enigmatic group. Copyright © 2016 Fullerton and Moyer.

Depositionally controlled recycling of iron and sulfur in marine sediments and its isotopic consequences

NASA Astrophysics Data System (ADS)

Riedinger, N.; Formolo, M.; Arnold, G. L.; Vossmeyer, A.; Henkel, S.; Sawicka, J.; Kasten, S.; Lyons, T. W.

2011-12-01

The continental margin off Uruguay and Argentina is characterized by highly dynamic depositional conditions. This variable depositional regime significantly impacts the biogeochemical cycles of iron and sulfur. Mass deposit related redeposition of reduced minerals can lead to the reoxidation of these phases and thus to an overprint of their geochemical primary signatures. Due to rapid burial these oxidized phases are still present in deeper subsurface sediments. To study the effects of sediment relocation on the sulfur and iron inventory we collected shallow and deep subsurface sediment samples via multicorer and gravity cores, respectively, in the western Argentine Basin during the RV Meteor Expedition M78/3 in May-July 2009. The samples were retrieved from shelf, slope and deep basin sites. The concentration and sulfur isotope composition of acid volatile sulfur (AVS), chromium reducible sulfur (CRS), elemental sulfur and total organic sulfur were determined. Furthermore, sequential iron extraction techniques were applied assess the distribution of iron oxide phases within the sediment. The investigated sediments are dominated by terrigenous inputs, with high amounts of reactive ferric iron minerals and only low concentrations of calcium carbonate. Total organic carbon concentrations show strong variation in the shallow subsurface sediments ranging between approximately 0.7 and 6.4 wt% for different sites. These concentrations do not correlate with water depths. Pore water accumulations of hydrogen sulfide are restricted to an interval at the sulfate-methane transition (SMT) zone a few meters below the sediment surface. In these deeper subsurface sediments pyrite is precipitated in this zone of hydrogen sulfide excess, whereas the accumulation of authigenic AVS and elemental sulfur (up to 2000 ppm) occurs at the upper and lower boundary of the sulfidic zone due the reaction of iron oxides with limited amounts of sulfide. Furthermore, our preliminary results indicate that there is a link between modern deposition in the shallow subsurface sediments and the long-term signals being buried and preserved in the deep subsurface layers. The data show that the burial of elemental sulfur into deep subsurface sediments can fuel the deep biosphere and has consequences for isotopic overprints tied, for example, to oxidation and disproportionation processes in the deeper sediments.

Change in ocean subsurface environment to suppress tropical cyclone intensification under global warming.

PubMed

Huang, Ping; Lin, I-I; Chou, Chia; Huang, Rong-Hui

2015-05-18

Tropical cyclones (TCs) are hazardous natural disasters. Because TC intensification is significantly controlled by atmosphere and ocean environments, changes in these environments may cause changes in TC intensity. Changes in surface and subsurface ocean conditions can both influence a TC's intensification. Regarding global warming, minimal exploration of the subsurface ocean has been undertaken. Here we investigate future subsurface ocean environment changes projected by 22 state-of-the-art climate models and suggest a suppressive effect of subsurface oceans on the intensification of future TCs. Under global warming, the subsurface vertical temperature profile can be sharpened in important TC regions, which may contribute to a stronger ocean coupling (cooling) effect during the intensification of future TCs. Regarding a TC, future subsurface ocean environments may be more suppressive than the existing subsurface ocean environments. This suppressive effect is not spatially uniform and may be weak in certain local areas.

Change in ocean subsurface environment to suppress tropical cyclone intensification under global warming

PubMed Central

Huang, Ping; Lin, I. -I; Chou, Chia; Huang, Rong-Hui

2015-01-01

Tropical cyclones (TCs) are hazardous natural disasters. Because TC intensification is significantly controlled by atmosphere and ocean environments, changes in these environments may cause changes in TC intensity. Changes in surface and subsurface ocean conditions can both influence a TC's intensification. Regarding global warming, minimal exploration of the subsurface ocean has been undertaken. Here we investigate future subsurface ocean environment changes projected by 22 state-of-the-art climate models and suggest a suppressive effect of subsurface oceans on the intensification of future TCs. Under global warming, the subsurface vertical temperature profile can be sharpened in important TC regions, which may contribute to a stronger ocean coupling (cooling) effect during the intensification of future TCs. Regarding a TC, future subsurface ocean environments may be more suppressive than the existing subsurface ocean environments. This suppressive effect is not spatially uniform and may be weak in certain local areas. PMID:25982028

Study of the Martian Subsurface with a Fiber Optics Spectrometer: the Ma_Miss Experiment

NASA Astrophysics Data System (ADS)

Coradini, A.; de Sanctis, M. C.; Ammannito, E.; Boccaccini, A.; Battistelli, E.; Capanni, A.

2009-04-01

In this presentation is described the investigation that we intend to do with a small imaging spectrometer that will be inserted in the drill of the Exomars- Pasteur rover. This spectrometer is named Ma_miss (Mars Multispectral Imager for Subsurface Studies ). The Ma_Miss experiment is located in the drill ,that will be able to make a hole in the Mars soil and rock up to 2 m. Ma_Miss includes the optical head of the spectrometer, a lamp to illuminate the borehole walls, and the optical fiber that brings the signal to the spectrometer. The multispectral images are acquired by means of a sapphire window placed on the lateral wall of the drill tool, as close as possible to the drill head. The images are gathered by means of an optical fibre system and analyzed using the spectrometer. The Ma_Miss gathered light containing the scientific information is transferred to the array detector and electronics of the instrument by means of an optical rotary joint implemented in the roto-translation group of the drill, as shown in the next pictures In the figure is schematically represented the Ma_Miss- Dibs architecture. This experiment will be extremely valuable since it will allow, for the first time, to have an idea of the mineralogical composition of the Martian subsurface and to study freshly cut rocks. The study of surface and subsurface mineralogy of Martian soil and rocks is the key for understanding the chemico-physical processes that led to the formation and evolution of the Red Planet. The history of the water and other volatiles, as well as the signatures of weathering processes are important to understand present and past environmental conditions associated with the possibility of life. Surface samples are highly influenced by exogenous processes (weathering, erosion, sedimentation, impact) that alter their original properties. So, the analyses of uncontaminated samples by means of instrumented drills and in situ analytic stations are the key for unambiguous interpretation of the original environment that leading to the formation of rocks. Analysis of subsurface layers is the only approach that warranties measurements on samples close to their original composition. The upper few meters of the surface materials on Mars play a crucial role in its history, providing important constraints geologic, hydrologic, and climatic to the history of the planet. Drilling into the near-surface crust will provide an opportunity to assess variations in composition, texture, stratification, unconformities, etc. that will help define its lithology and structure, and provide important clues regarding its origin and subsequent evolution. The subsurface material can give information on the evolution of surface sediments (erosion, transport, deposition), on the relation between sediments and bedrock, on the relation between environmental conditions and surface processes permitting to "investigate planetary processes that influence habitability." Investigation of mineralogical composition of near-surface geological materials is needed to fully characterize the geology of the regions that will be visited by the Rover at all appropriate spatial scales, and to interpret the processes that have formed and modified rocks and regolith. Subsurface access, sampling material below the oxidized layer, can be the key to "assess the biological potential of the target environment (past or present)". To date, we have direct observations relative only to the Martian surface. Little is known about the characteristics of the first subsurface layers. The possibility to sample subsurface materials to be delivered to other instruments, and to record the context of the sampled soil doing in situ borehole mineralogical analysis, is fundamental to search for traces of past or present life on Mars. The spectrometer observes a single point target, having 0.1 mm diameter, on the borehole wall surface. Depending on the surface features we are interested in, the observation window can scan the borehole's surface by means of drill tip rotation or translation. When the drill is translated, a "Column Image" is acquired. This translation step can be equal to the observation spot (0.1 mm). The "Ring Image" can be obtained by rotation of the drill tip; a rotation step of about 0.5˚ (corresponding to 720 acquisitions in the ring) is sufficient to assure the full coverage of the ring.

Visible-Near Infrared Point Spectrometry of Drill Core Samples from Río Tinto, Spain: Results from the 2005 Mars Astrobiology Research and Technology Experiment (MARTE) Drilling Exercise

NASA Astrophysics Data System (ADS)

Sutter, Brad; Brown, Adrian J.; Stoker, Carol R.

2008-10-01

Sampling of subsurface rock may be required to detect evidence of past biological activity on Mars. The Mars Astrobiology Research and Technology Experiment (MARTE) utilized the Río Tinto region, Spain, as a Mars analog site to test dry drilling technologies specific to Mars that retrieve subsurface rock for biological analysis. This work examines the usefulness of visible-near infrared (VNIR) (450-1000 nm) point spectrometry to characterize ferric iron minerals in core material retrieved during a simulated Mars drilling mission. VNIR spectrometry can indicate the presence of aqueously precipitated ferric iron minerals and, thus, determine whether biological analysis of retrieved rock is warranted. Core spectra obtained during the mission with T1 (893-897 nm) and T2 (644-652 nm) features indicate goethite-dominated samples, while relatively lower wavelength T1 (832-880 nm) features indicate hematite. Hematite/goethite molar ratios varied from 0 to 1.4, and within the 880-898 nm range, T1 features were used to estimate hematite/goethite molar ratios. Post-mission X-ray analysis detected phyllosilicates, which indicates that examining beyond the VNIR (e.g., shortwave infrared, 1000-2500 nm) will enhance the detection of other minerals formed by aqueous processes. Despite the limited spectral range of VNIR point spectrometry utilized in the MARTE Mars drilling simulation project, ferric iron minerals could be identified in retrieved core material, and their distribution served to direct core subsampling for biological analysis.

Visible-near infrared point spectrometry of drill core samples from Río Tinto, Spain: results from the 2005 Mars Astrobiology Research and Technology Experiment (MARTE) drilling exercise.

PubMed

Sutter, Brad; Brown, Adrian J; Stoker, Carol R

2008-10-01

Sampling of subsurface rock may be required to detect evidence of past biological activity on Mars. The Mars Astrobiology Research and Technology Experiment (MARTE) utilized the Río Tinto region, Spain, as a Mars analog site to test dry drilling technologies specific to Mars that retrieve subsurface rock for biological analysis. This work examines the usefulness of visible-near infrared (VNIR) (450-1000 nm) point spectrometry to characterize ferric iron minerals in core material retrieved during a simulated Mars drilling mission. VNIR spectrometry can indicate the presence of aqueously precipitated ferric iron minerals and, thus, determine whether biological analysis of retrieved rock is warranted. Core spectra obtained during the mission with T1 (893-897 nm) and T2 (644-652 nm) features indicate goethite-dominated samples, while relatively lower wavelength T1 (832-880 nm) features indicate hematite. Hematite/goethite molar ratios varied from 0 to 1.4, and within the 880-898 nm range, T1 features were used to estimate hematite/goethite molar ratios. Post-mission X-ray analysis detected phyllosilicates, which indicates that examining beyond the VNIR (e.g., shortwave infrared, 1000-2500 nm) will enhance the detection of other minerals formed by aqueous processes. Despite the limited spectral range of VNIR point spectrometry utilized in the MARTE Mars drilling simulation project, ferric iron minerals could be identified in retrieved core material, and their distribution served to direct core subsampling for biological analysis.

Exploring the utility of real-time hydrologic data for landslide early warning

NASA Astrophysics Data System (ADS)

Mirus, B. B.; Smith, J. B.; Becker, R.; Baum, R. L.; Koss, E.

2017-12-01

Early warning systems can provide critical information for operations managers, emergency planners, and the public to help reduce fatalities, injuries, and economic losses due to landsliding. For shallow, rainfall-triggered landslides early warning systems typically use empirical rainfall thresholds, whereas the actual triggering mechanism involves the non-linear hydrological processes of infiltration, evapotranspiration, and hillslope drainage that are more difficult to quantify. Because hydrologic monitoring has demonstrated that shallow landslides are often preceded by a rise in soil moisture and pore-water pressures, some researchers have developed early warning criteria that attempt to account for these antecedent wetness conditions through relatively simplistic storage metrics or soil-water balance modeling. Here we explore the potential for directly incorporating antecedent wetness into landslide early warning criteria using recent landslide inventories and in-situ hydrologic monitoring near Seattle, WA, and Portland, OR. We use continuous, near-real-time telemetered soil moisture and pore-water pressure data measured within a few landslide-prone hillslopes in combination with measured and forecasted rainfall totals to inform easy-to-interpret landslide initiation thresholds. Objective evaluation using somewhat limited landslide inventories suggests that our new thresholds based on subsurface hydrologic monitoring and rainfall data compare favorably to the capabilities of existing rainfall-only thresholds for the Seattle area, whereas there are no established rainfall thresholds for the Portland area. This preliminary investigation provides a proof-of-concept for the utility of developing landslide early warning criteria in two different geologic settings using real-time subsurface hydrologic measurements from in-situ instrumentation.

An innovative computationally efficient hydromechanical coupling approach for fault reactivation in geological subsurface utilization

NASA Astrophysics Data System (ADS)

Adams, M.; Kempka, T.; Chabab, E.; Ziegler, M.

2018-02-01

Estimating the efficiency and sustainability of geological subsurface utilization, i.e., Carbon Capture and Storage (CCS) requires an integrated risk assessment approach, considering the occurring coupled processes, beside others, the potential reactivation of existing faults. In this context, hydraulic and mechanical parameter uncertainties as well as different injection rates have to be considered and quantified to elaborate reliable environmental impact assessments. Consequently, the required sensitivity analyses consume significant computational time due to the high number of realizations that have to be carried out. Due to the high computational costs of two-way coupled simulations in large-scale 3D multiphase fluid flow systems, these are not applicable for the purpose of uncertainty and risk assessments. Hence, an innovative semi-analytical hydromechanical coupling approach for hydraulic fault reactivation will be introduced. This approach determines the void ratio evolution in representative fault elements using one preliminary base simulation, considering one model geometry and one set of hydromechanical parameters. The void ratio development is then approximated and related to one reference pressure at the base of the fault. The parametrization of the resulting functions is then directly implemented into a multiphase fluid flow simulator to carry out the semi-analytical coupling for the simulation of hydromechanical processes. Hereby, the iterative parameter exchange between the multiphase and mechanical simulators is omitted, since the update of porosity and permeability is controlled by one reference pore pressure at the fault base. The suggested procedure is capable to reduce the computational time required by coupled hydromechanical simulations of a multitude of injection rates by a factor of up to 15.

Subsurface characterization by the ground penetrating radar WISDOM/ExoMars 2020

NASA Astrophysics Data System (ADS)

Hervé, Y.; Ciarletti, V.; Le Gall, A. A.; Oudart, N.; Loizeau, D.; Guiffaut, C.; Dorizon, S.

2017-12-01

The main objective of the ExoMars 2020 mission is to search for signs of past and/or present life on Mars. Toward this goal, a rover was designed to investigate the shallow subsurface which is the most likely place where signs of life may be preserved, beneath the hostile surface of Mars. The rover of the ExoMars 2020 mission has on board a polarimetric ground penetrating radar called WISDOM (Water Ice Subsurface Deposits Observation on Mars). Thanks to its large frequency bandwidth of 2.5 GHz, WISDOM is able to probe down to a depth of approximately 3 m on sedimentary rock with a vertical resolution of a few centimeters.The main scientific objectives of WISDOM are to characterize the shallow subsurface of Mars, to help understand the local geological context and to identify the most promising location for drilling. The WISDOM team is currently working on the preparation of the scientific return of the ExoMars 2020 mission. In particular, tools are developed to interpret WISDOM experimental data and, more specifically, to extract information from the radar signatures of expected buried reflectors. Insights into the composition of the ground (through the retrieval of its permittivity) and the geological context of the site can be inferred from the radar signature of buried rocks since the shape and the density of rocks in the subsurface is related to the geological processes that have shaped and placed them there (impact, fluvial processes, volcanism). This paper presents results obtained by automatic detection of structures of interest on a radargram, especially radar signature of buried rocks. The algorithm we developed uses a neural network to identify the position of buried rocks/blocs and then a Hough transform to characterize each signature and to estimate the local permittivity of the medium. Firstly, we will test the performances of the algorithm on simulated data constructed with a 3D FDTD code. This code allows us to simulate radar operation in realistic environments. Secondly, we will test our algorithm on experimental data acquired in a semi-controlled environment. Lastly, we will present experimental data acquired during a recent field campaign (July 2017) in the south of France and we will validate our method and illustrate the ability of WISDOM to provide clues about the geological context of a site.

Ocean Drilling Program Contributions to the Understanding of the Deep Subsurface Biosphere

NASA Astrophysics Data System (ADS)

Fisk, M. R.

2003-12-01

Tantalizing evidence for microbes in oceanic basalts has been reported for a few decades, but it was from rocks cored on Ocean Drilling Program (ODP) Leg 148 in 1993 that the first clear-cut evidence of microbial invasion of ocean basalts was obtained. (Work on ODP legs, starting with Leg 112 in 1986, had already revealed the presence of significant microbial biomass in sediments.) In 1997 ODP created the Deep Biosphere Program Planning Group to promote the investigation of the microbiology of the ocean crust. In 1999 ODP built a microbiology lab on the JOIDES Resolution, and used the lab that year (Legs 185 and 187) to test the amount of microbial contamination introduced into rocks during drilling and to establish cultures from cored basalts. These experiments have been repeated on several legs since then. The development of CORKs has permitted long-term sampling of subseafloor fluids, and microorganisms have been recovered from CORKed holes. Thus, ODP made it possible for the scientific community to address major questions about the biology of the igneous crust, such as, (1) What microbes are present? (2) How abundant are they? (3) How are they distributed? DNA from basalts and subseafloor fluids reveal what types of organisms are present. Cell abundance and biomass have been estimated based on cell counts and on organic content of basalts. Surveys of basalts in DSDP/ODP repositories indicate that microorganisms are ubiquitous in the igneous crust. Microorganisms are found in rocks that are close to 100° C. They are found as deep as 1500 m below the sea floor, and in rocks as young as a few years and as old as 170 million years. Because of the vast size of the habitat, microorganism, even if present in small numbers, could be a significant fraction of the Earth's biomass. In a short time ODP contributed to advances in our understanding of the oceanic subsurface biosphere. Answers to other significant questions such as: (1) How do the microorganisms live?, (2) What impact do subsurface microorganisms have on the surface biosphere? (3) And, what roles do the subsurface biosphere play in element cycling? will be answered by future drilling. The International Ocean Drilling Program (IODP) is in the enviable position of providing support to address these key questions about the Earth's subsurface biosphere.

A comparison of high-resolution specific conductance-based end-member mixing analysis and a graphical method for baseflow separation of four streams in hydrologically challenging agricultural watersheds

USGS Publications Warehouse

Kronholm, Scott C.; Capel, Paul D.

2015-01-01

Quantifying the relative contributions of different sources of water to a stream hydrograph is important for understanding the hydrology and water quality dynamics of a given watershed. To compare the performance of two methods of hydrograph separation, a graphical program [baseflow index (BFI)] and an end-member mixing analysis that used high-resolution specific conductance measurements (SC-EMMA) were used to estimate daily and average long-term slowflow additions of water to four small, primarily agricultural streams with different dominant sources of water (natural groundwater, overland flow, subsurface drain outflow, and groundwater from irrigation). Because the result of hydrograph separation by SC-EMMA is strongly related to the choice of slowflow and fastflow end-member values, a sensitivity analysis was conducted based on the various approaches reported in the literature to inform the selection of end-members. There were substantial discrepancies among the BFI and SC-EMMA, and neither method produced reasonable results for all four streams. Streams that had a small difference in the SC of slowflow compared with fastflow or did not have a monotonic relationship between streamflow and stream SC posed a challenge to the SC-EMMA method. The utility of the graphical BFI program was limited in the stream that had only gradual changes in streamflow. The results of this comparison suggest that the two methods may be quantifying different sources of water. Even though both methods are easy to apply, they should be applied with consideration of the streamflow and/or SC characteristics of a stream, especially where anthropogenic water sources (irrigation and subsurface drainage) are present.

Hydrogeologic controls on episodic H2 release from precambrian fractured rocks--energy for deep subsurface life on earth and mars.

PubMed

Sherwood Lollar, B; Voglesonger, K; Lin, L-H; Lacrampe-Couloume, G; Telling, J; Abrajano, T A; Onstott, T C; Pratt, L M

2007-12-01

Dissolved H(2) concentrations up to the mM range and H(2) levels up to 9-58% by volume in the free gas phase are reported for groundwaters at sites in the Precambrian shields of Canada and Finland. Along with previously reported dissolved H(2) concentrations up to 7.4 mM for groundwaters from the Witwatersrand Basin, South Africa, these findings indicate that deep Precambrian Shield fracture waters contain some of the highest levels of dissolved H(2) ever reported and represent a potentially important energy-rich environment for subsurface microbial life. The delta (2)H isotope signatures of H(2) gas from Canada, Finland, and South Africa are consistent with a range of H(2)-producing water-rock reactions, depending on the geologic setting, which include both serpentinization and radiolysis. In Canada and Finland, several of the sites are in Archean greenstone belts characterized by ultramafic rocks that have under-gone serpentinization and may be ancient analogues for serpentinite-hosted gases recently reported at the Lost City Hydrothermal Field and other hydrothermal seafloor deposits. The hydrogeologically isolated nature of these fracture-controlled groundwater systems provides a mechanism whereby the products of water-rock interaction accumulate over geologic timescales, which produces correlations between high H(2) levels, abiogenic hydrocarbon signatures, and the high salinities and highly altered delta (18)O and delta (2)H values of these groundwaters. A conceptual model is presented that demonstrates how periodic opening of fractures and resultant mixing control the distribution and supply of H(2) and support a microbial community of H(2)-utilizing sulfate reducers and methanogens.

Microstructural investigation of vintage pipeline steels highly susceptible to stress corrosion cracking

NASA Astrophysics Data System (ADS)

Torres, Monica

The use of pipelines for the transmission of gas offers not only efficiency, but a number of economic advantages. Nevertheless, pipelines are subject to aggressive operating conditions and environments which can lead to in-service degradation [1] and thus to failures. These failures can have catastrophic consequences, such as environmental damage and loss of life [2]. One of the most dangerous threats to pipeline integrity is stress corrosion cracking (SCC). Despite the substantial progress that has been achieved in the field, due to the complex nature of this phenomenon there is still not a complete understanding of this form of external corrosion. This makes its detection and prevention a challenge and therefore a risk to pipeline integrity, and most importantly, to the safety of the population. SCC cracks are the result of the interaction between a corrosive environment, applied stresses, and a susceptible microstructure. To date, what defines a susceptible microstructure remains ambiguous, as SCC has been observed in a range of steel grades, microstructures, chemical composition, and grain sizes. Therefore, in order to be able to accurately predict and prevent this hazardous form of corrosion, it is imperative to advance our knowledge on the subject and gain a better understanding on the microstructural features of highly susceptible pipeline materials, especially in the subsurface zone where crack nucleation must take place. Therefore, a microstructural characterization of the region near the surface layer was carried-out utilizing TEM. TEM analysis revealed the dislocation character, ferrite morphology, and apparent carbide precipitation in some grain boundaries. Furthermore, light microscopy, SEM, and hardness testing were performed to expand our knowledge on the microscopical features of highly SCC susceptible service components. This investigation presents a new approach to SCC characterization, which exposed the sub-surface region microscopical characteristics of service components with confirmed SCC.

The hydrodynamics of plant spacing distance: Optimizing consumptive and non-consumptive water use in water-limited environments

NASA Astrophysics Data System (ADS)

Trautz, A.; Illangasekare, T. H.; Rodriguez-Iturbe, I.; Howington, S. E.

2017-12-01

The availability of soil moisture in water-stressed environments is one of the primary factors controlling plant performance and overall plant community productivity and structure. The minimization of non-consumptive water loss, or water not utilized by plants (i.e. consumptive use), to bare soil evaporation is a key plant survival strategy and important agricultural consideration. Competitive (negative) and facilitative (positive) interactions between individual plants play a pivotal role in controlling the local coupled soil-plant-atmosphere hydrodynamics that affect both consumptive and non-consumptive water use. The strength of these two types of interactions vary with spacing distance between individuals. In a recent PNAS publication, we hypothesized that there exists a quantifiable spacing distance between plants that optimizes the balance between competition and facilitation, and hence maximizes water conservation. This study expands upon on our previous work, for which only a subset of the data generated was used, through the development and testing of a numerical model that can test a conceptual model we presented. The model simulates soil-plant-atmosphere continuum heat and mass transfer hydrodynamics, taking into account the complex feedbacks that exist between the near-surface atmosphere, subsurface, and plants. This model has been developed to explore the combined effects of subsurface competition and micro-climatic amelioration (i.e., facilitation) on local soil moisture redistribution and fluxes in the context of water-stressed environments that experienced sustained winds. We believe the results have the potential to provide new insights into climatological, ecohydrological, and hydrological problems pertaining to: the extensively used and much debated stress-gradient hypothesis, plant community population self-organization, agricultural best practices (e.g., water management), and spatial heterogeneity of land-atmosphere fluxes.

Insights into plant water uptake from xylem-water isotope measurements in two tropical catchments with contrasting moisture conditions

USGS Publications Warehouse

Evaristo, Jaivime; McDonnell, Jeffrey J.; Scholl, Martha A.; Bruijnzeel, L. Adrian; Chun, Kwok P.

2016-01-01

Water transpired by trees has long been assumed to be sourced from the same subsurface water stocks that contribute to groundwater recharge and streamflow. However, recent investigations using dual water stable isotopes have shown an apparent ecohydrological separation between tree-transpired water and stream water. Here we present evidence for such ecohydrological separation in two tropical environments in Puerto Rico where precipitation seasonality is relatively low and where precipitation is positively correlated with primary productivity. We determined the stable isotope signature of xylem water of 30 mahogany (Swietenia spp.) trees sampled during two periods with contrasting moisture status. Our results suggest that the separation between transpiration water and groundwater recharge/streamflow water might be related less to the temporal phasing of hydrologic inputs and primary productivity, and more to the fundamental processes that drive evaporative isotopic enrichment of residual soil water within the soil matrix. The lack of an evaporative signature of both groundwater and streams in the study area suggests that these water balance components have a water source that is transported quickly to deeper subsurface storage compared to waters that trees use. A Bayesian mixing model used to partition source water proportions of xylem water showed that groundwater contribution was greater for valley-bottom, riparian trees than for ridge-top trees. Groundwater contribution was also greater at the xeric site than at the mesic–hydric site. These model results (1) underline the utility of a simple linear mixing model, implemented in a Bayesian inference framework, in quantifying source water contributions at sites with contrasting physiographic characteristics, and (2) highlight the informed judgement that should be made in interpreting mixing model results, of import particularly in surveying groundwater use patterns by vegetation from regional to global scales. 

Microfluidic Experiments Studying Pore Scale Interactions of Microbes and Geochemistry

NASA Astrophysics Data System (ADS)

Chen, M.; Kocar, B. D.

2016-12-01

Understanding how physical phenomena, chemical reactions, and microbial behavior interact at the pore-scale is crucial to understanding larger scale trends in groundwater chemistry. Recent studies illustrate the utility of microfluidic devices for illuminating pore-scale physical-biogeochemical processes and their control(s) on the cycling of iron, uranium, and other important elements 1-3. These experimental systems are ideal for examining geochemical reactions mediated by microbes, which include processes governed by complex biological phenomenon (e.g. biofilm formation, etc.)4. We present results of microfluidic experiments using a model metal reducing bacteria and varying pore geometries, exploring the limitations of the microorganisms' ability to access tight pore spaces, and examining coupled biogeochemical-physical controls on the cycling of redox sensitive metals. Experimental results will provide an enhanced understanding of coupled physical-biogeochemical processes transpiring at the pore-scale, and will constrain and compliment continuum models used to predict and describe the subsurface cycling of redox-sensitive elements5. 1. Vrionis, H. A. et al. Microbiological and geochemical heterogeneity in an in situ uranium bioremediation field site. Appl. Environ. Microbiol. 71, 6308-6318 (2005). 2. Pearce, C. I. et al. Pore-scale characterization of biogeochemical controls on iron and uranium speciation under flow conditions. Environ. Sci. Technol. 46, 7992-8000 (2012). 3. Zhang, C., Liu, C. & Shi, Z. Micromodel investigation of transport effect on the kinetics of reductive dissolution of hematite. Environ. Sci. Technol. 47, 4131-4139 (2013). 4. Ginn, T. R. et al. Processes in microbial transport in the natural subsurface. Adv. Water Resour. 25, 1017-1042 (2002). 5. Scheibe, T. D. et al. Coupling a genome-scale metabolic model with a reactive transport model to describe in situ uranium bioremediation. Microb. Biotechnol. 2, 274-286 (2009).

Microbial Diversity Associated With Geochemical Changes in a Deep Subsurface Aquifer

NASA Astrophysics Data System (ADS)

Davidson, M. M.; Onstott, T. C.; Pratt, L. M.; Boice, E.; Southam, G.; Wanger, G.; Sherwood-Lollar, B.; Lippmann, J.; Seymoor, W.

2003-12-01

The microbial diversity of a 1.83km deep, thermophilic, fluid-filled subterranean fracture was monitored over a three and a half month period and correlated to observed changes in the geochemistry of the system. Three water samples were analyzed using 16S rDNA molecular techniques for microbial diversity, isotopic and geochemical composition. Gibbs' free energy of microbial redox reactions predicted that at in situ conditions sulfate reduction, methanogenesis and acetogenesis should be dominant metabolic pathways utilized by microbes, whereas Fe(III)-reduction should only have been favorable in the last sample. Noble gas isotopic data yielded a subsurface residence time of ˜10-100 Myr. and the non-meteoric δ D vs. δ 18O values were indicative of water-rock alteration at <100° C. δ 34S of sulfide and sulfate differed by 15‰ , consistent with fractionation by sulfate reducing bacteria. H2 concentrations declined with time, which in conjunction with the δ 34S data, suggested that hydrogenotrophic sulfate reducing bacteria dominate the community. This was compatible with 16S rDNA analysis, which yielded clones similar to Desulfotomaculum and Desulfofustis species appearing in the three 16S libraries. δ 13C and δ D values of CH4 and light hydrocarbons indicated methanogenic CH4 was mixing with abiogenically formed CH4. This is consistent with the presence of Archaeal 16S sequences similar to Methanosaeta and Methanosarcina species. The temporal increase in acetate concentration could be attributed to clone types similar to known acetogenic bacteria such as Moorella glycerini, which were present in the last sample. Clones similar to known Fe(III)-reducing bacteria such as Geovibrio species were observed in the first and last samples.

Time-lapse 3-D seismic imaging of shallow subsurface contaminant flow.

PubMed

McKenna, J; Sherlock, D; Evans, B

2001-12-01

This paper presents a physical modelling study outlining a technique whereby buoyant contaminant flow within water-saturated unconsolidated sand was remotely monitored utilizing the time-lapse 3-D (TL3-D) seismic response. The controlled temperature and pressure conditions, along with the high level of acquisition repeatability attainable using sandbox physical models, allow the TL3-D seismic response to pore fluid movement to be distinguished from all other effects. TL3-D seismic techniques are currently being developed to monitor hydrocarbon reserves within producing reservoirs in an endeavour to improve overall recovery. However, in many ways, sandbox models under atmospheric conditions more accurately simulate the shallow subsurface than petroleum reservoirs. For this reason, perhaps the greatest application for analogue sandbox modelling is to improve our understanding of shallow groundwater and environmental flow mechanisms. Two fluid flow simulations were conducted whereby air and kerosene were injected into separate water-saturated unconsolidated sand models. In both experiments, a base 3-D seismic volume was recorded and compared with six later monitor surveys recorded while the injection program was conducted. Normal incidence amplitude and P-wave velocity information were extracted from the TL3-D seismic data to provide visualization of contaminant migration. Reflection amplitudes displayed qualitative areal distribution of fluids when a suitable impedance contrast existed between pore fluids. TL3-D seismic reflection tomography can potentially monitor the change in areal distribution of fluid contaminants over time, indicating flow patterns. However, other research and this current work have not established a quantifiable relationship between either normal reflection amplitudes and attenuation and fluid saturation. Generally, different pore fluids will have unique seismic velocities due to differences in compressibility and density. The predictable relationships that exist between P-wave velocity and fluid saturation can allow a quantitative assessment of contaminant migration.

Mars Exploration Rovers as Virtual Instruments for Determination of Terrain Roughness and Physical Properties

NASA Technical Reports Server (NTRS)

Arvidson, R. E.; Lindemann, R.; Matijevic, J.; Richter, L.; Sullivan, R.; Haldemann, A.; Anderson, R.; Snider, N.

2003-01-01

The two 2003 Mars Exploration Rovers (MERs), in combination with the Athena Payload, will be used as virtual instrument systems to infer terrain properties during traverses, in addition to using the rover wheels to excavate trenches, exposing subsurface materials for remote and in-situ observations. The MERs are being modeled using finite element-based rover system transfer functions that utilize the distribution of masses associated with the vehicle, together with suspension and wheel dynamics, to infer surface roughness and mechanical properties from traverse time series data containing vehicle yaw, pitch, roll, encoder counts, and motor currents. These analyses will be supplemented with imaging and other Athena Payload measurements. The approach is being validated using Sojourner data, the FIDO rover, and experiments with MER testbed vehicles. In addition to conducting traverse science and associated analyses, trenches will be excavated by the MERs to depths of approximately 10-20 cm by locking all but one of the front wheels and rotating that wheel backwards so that the excavated material is piled up on the side of the trench away from the vehicle. Soil cohesion and angle of internal friction will be determined from the trench telemetry data. Emission spectroscopy and in-situ observations will be made using the Athena payload before and after imaging. Trenching and observational protocols have been developed using Sojourner results; data from the FIDO rover, including trenches dug into sand, mud cracks, and weakly indurated bedrock; and experiments with MER testbed rovers. Particular attention will be focused on Mini-TES measurements designed to determine the abundance and state of subsurface water (e.g. hydrated, in zeolites, residual pore ice?) predicted to be present from Odyssey GRS/NS/HEND data.

Subsurface structure of the East Bay Plain ground-water basin: San Francisco Bay to the Hayward fault, Alameda County, California

USGS Publications Warehouse

Catchings, R.D.; Borchers, J.W.; Goldman, M.R.; Gandhok, G.; Ponce, D.A.; Steedman, C.E.

2006-01-01

The area of California between the San Francisco Bay, San Pablo Bay, Santa Clara Valley, and the Diablo Ranges (East Bay Hills), commonly referred to as the 'East Bay', contains the East Bay Plain and Niles Cone ground-water basins. The area has a population of 1.46 million (2003 US Census), largely distributed among several cities, including Alameda, Berkeley, Fremont, Hayward, Newark, Oakland, San Leandro, San Lorenzo, and Union City. Major known tectonic structures in the East Bay area include the Hayward Fault and the Diablo Range to the east and a relatively deep sedimentary basin known as the San Leandro Basin beneath the eastern part of the bay. Known active faults, such as the Hayward, Calaveras, and San Andreas pose significant earthquake hazards to the region, and these and related faults also affect ground-water flow in the San Francisco Bay area. Because most of the valley comprising the San Francisco Bay area is covered by Holocene alluvium or water at the surface, our knowledge of the existence and locations of such faults, their potential hazards, and their effects on ground-water flow within the alluvial basins is incomplete. To better understand the subsurface stratigraphy and structures and their effects on ground-water and earthquake hazards, the U.S. Geological Survey (USGS), in cooperation with the East Bay Municipal Utility District (EBMUD), acquired a series of high-resolution seismic reflection and refraction profiles across the East Bay Plain near San Leandro in June 2002. In this report, we present results of the seismic imaging investigations, with emphasis on ground water.

Molecular Phylogenetic Analysis of Archaeal Intron-Containing Genes Coding for rRNA Obtained from a Deep-Subsurface Geothermal Water Pool

PubMed Central

Takai, Ken; Horikoshi, Koki

1999-01-01

Molecular phylogenetic analysis of a naturally occurring microbial community in a deep-subsurface geothermal environment indicated that the phylogenetic diversity of the microbial population in the environment was extremely limited and that only hyperthermophilic archaeal members closely related to Pyrobaculum were present. All archaeal ribosomal DNA sequences contained intron-like sequences, some of which had open reading frames with repeated homing-endonuclease motifs. The sequence similarity analysis and the phylogenetic analysis of these homing endonucleases suggested the possible phylogenetic relationship among archaeal rRNA-encoded homing endonucleases. PMID:10584021

Nonlinear scattering of acoustic waves by natural and artificially generated subsurface bubble layers in sea.

PubMed

Ostrovsky, Lev A; Sutin, Alexander M; Soustova, Irina A; Matveyev, Alexander L; Potapov, Andrey I; Kluzek, Zigmund

2003-02-01

The paper describes nonlinear effects due to a biharmonic acoustic signal scattering from air bubbles in the sea. The results of field experiments in a shallow sea are presented. Two waves radiated at frequencies 30 and 31-37 kHz generated backscattered signals at sum and difference frequencies in a bubble layer. A motorboat propeller was used to generate bubbles with different concentrations at different times, up to the return to the natural subsurface layer. Theoretical consideration is given for these effects. The experimental data are in a reasonably good agreement with theoretical predictions.

Novel Real-Time Facial Wound Recovery Synthesis Using Subsurface Scattering

PubMed Central

Chin, Seongah

2014-01-01

We propose a wound recovery synthesis model that illustrates the appearance of a wound healing on a 3-dimensional (3D) face. The H3 model is used to determine the size of the recovering wound. Furthermore, we present our subsurface scattering model that is designed to take the multilayered skin structure of the wound into consideration to represent its color transformation. We also propose a novel real-time rendering method based on the results of an analysis of the characteristics of translucent materials. Finally, we validate the proposed methods with 3D wound-simulation experiments using shading models. PMID:25197721

WISDOM measurements in a cold artificial and controlled environment

NASA Astrophysics Data System (ADS)

Dechambre, M.; Saintenoy, A.; Ciarletti, V.; Biancheri-Astier, M.; Costard, F.; Hassen-Khodja, R.

2011-10-01

The WISDOM (500MHz - 3GHz) GPR is one of the instruments that have been selected as part of the Pasteur payload of ESA's 2018 ExoMars Rover mission. One of the main scientific objectives of the mission is to characterize the nature of the shallow sub-surface on Mars and WISDOM has been designed to explore the first ~ 3 meters of the subsurface with a vertical resolution of a few centimetres. Full polarimetric measurements in cold artificial and controlled conditions have been performed by the prototype to illustrate and quantify the instrument performance. Preliminary results are presented.

The microwave spectrum and nature of the subsurface of Mars.

NASA Technical Reports Server (NTRS)

Cuzzi, J. N.; Muhleman, D. O.

1972-01-01

Expected microwave spectra of Mars are computed using an improved thermal model and accurate aspect geometry. It is found that when seasonal polar cap effects are included in the calculations, the observable spectrum of Mars is flat from 0.1-21 cm to within the accuracy of present data. The spectra obtained from this model are consistent with all the data and are obtainable from a relatively simple model (homogeneous, dry, smooth dielectric sphere). This result differs from that predicted by the analytical theory in common use which is in apparent conflict with the observed spectra. A range of electrical loss tangents, covering the extreme limits for likely dry particulate geological materials, is employed. The case of a lunar-like subsurface is completely consistent with all present data.

Status of the ExoMars Project

NASA Astrophysics Data System (ADS)

Kminek, Gerhard; Vago, Jorge; Gianfiglio, Giacinto; Haldemann, Albert; Elfving, Anders; Pinel, Jacques; McCoy, Don

The ExoMars mission will deploy two science elements on the Martian surface: a rover and a small, fixed package. The fixed Humboldt science package, will measure planetary geophysics parameters important for understanding Mars's evolution and habitability, identify possible surface hazards to future human missions, and study the environment. The Rover Pasteur science package will search for signs of past and present life on Mars, and characterise the water and geochemical environment with depth by collecting and analysing subsurface samples down to 2 meters. The very powerful combination of surface mobility and subsurface access to locations where organic molecules may be well-preserved is unique to this mission. ExoMars is currently in Phase B prior to PDR. This presentation will provide an update on the project status, including instrument and technology developments.

Method for Implementing Subsurface Solid Derived Concentration Guideline Levels (DCGL) - 12331

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lively, J.W.

2012-07-01

The U.S. Nuclear Regulatory Commission (NRC) and other federal agencies currently approve the Multi-Agency Radiation Site Survey and Investigation Manual (MARSSIM) as guidance for licensees who are conducting final radiological status surveys in support of decommissioning. MARSSIM provides a method to demonstrate compliance with the applicable regulation by comparing residual radioactivity in surface soils with derived concentration guideline levels (DCGLs), but specifically discounts its applicability to subsurface soils. Many sites and facilities undergoing decommissioning contain subsurface soils that are potentially impacted by radiological constituents. In the absence of specific guidance designed to address the derivation of subsurface soil DCGLs andmore » compliance demonstration, decommissioning facilities have attempted to apply DCGLs and final status survey techniques designed specifically for surface soils to subsurface soils. The decision to apply surface soil limits and surface soil compliance metrics to subsurface soils typically results in significant over-excavation with associated cost escalation. MACTEC, Inc. has developed the overarching concepts and principles found in recent NRC decommissioning guidance in NUREG 1757 to establish a functional method to derive dose-based subsurface soil DCGLs. The subsurface soil method developed by MACTEC also establishes a rigorous set of criterion-based data evaluation metrics (with analogs to the MARSSIM methodology) that can be used to demonstrate compliance with the developed subsurface soil DCGLs. The method establishes a continuum of volume factors that relate the size and depth of a volume of subsurface soil having elevated concentrations of residual radioactivity with its ability to produce dose. The method integrates the subsurface soil sampling regime with the derivation of the subsurface soil DCGL such that a self-regulating optimization is naturally sought by both the responsible party and regulator. This paper describes the concepts and basis used by MACTEC to develop the dose-based subsurface soil DCGL method. The paper will show how MACTEC's method can be used to demonstrate that higher concentrations of residual radioactivity in subsurface soils (as compared with surface soils) can meet the NRC's dose-based regulations. MACTEC's method has been used successfully to obtain the NRC's radiological release at a site with known radiological impacts to subsurface soils exceeding the surface soil DCGL, saving both time and cost. Having considered the current NRC guidance for consideration of residual radioactivity in subsurface soils during decommissioning, MACTEC has developed a technically based approach to the derivation of and demonstration of compliance with subsurface soil DCGLs for radionuclides. In fact, the process uses the already accepted concepts and metrics approved for surface soils as the foundation for deriving scaling factors used to calculate subsurface soil DCGLs that are at least equally protective of the decommissioning annual dose standard. Each of the elements identified for consideration in the current NRC guidance is addressed in this proposed method. Additionally, there is considerable conservatism built into the assumptions and techniques used to arrive at subsurface soil scaling factors and DCGLs. The degree of conservatism embodied in the approach used is such that risk managers and decision makers approving and using subsurface soil DCGLs derived in accordance with this method can be confident that the future exposures will be well below permissible and safe levels. The technical basis for the method can be applied to a broad variety of sites with residual radioactivity in subsurface soils. Given the costly nature of soil surveys, excavation, and disposal of soils as low-level radioactive waste, MACTEC's method for deriving and demonstrating compliance with subsurface soil DCGLs offers the possibility of significant cost savings over the traditional approach of applying surface soil DCGLs to subsurface soils. Furthermore, while yet untested, MACTEC believes that the concepts and methods embodied in this approach could readily be applied to other types of contamination found in subsurface soils. (author)« less