Improving National Water Modeling: An Intercomparison of two High-Resolution, Continental Scale Models, CONUS-ParFlow and the National Water Model

NASA Astrophysics Data System (ADS)

Tijerina, D.; Gochis, D.; Condon, L. E.; Maxwell, R. M.

2017-12-01

Development of integrated hydrology modeling systems that couple atmospheric, land surface, and subsurface flow is growing trend in hydrologic modeling. Using an integrated modeling framework, subsurface hydrologic processes, such as lateral flow and soil moisture redistribution, are represented in a single cohesive framework with surface processes like overland flow and evapotranspiration. There is a need for these more intricate models in comprehensive hydrologic forecasting and water management over large spatial areas, specifically the Continental US (CONUS). Currently, two high-resolution, coupled hydrologic modeling applications have been developed for this domain: CONUS-ParFlow built using the integrated hydrologic model ParFlow and the National Water Model that uses the NCAR Weather Research and Forecasting hydrological extension package (WRF-Hydro). Both ParFlow and WRF-Hydro include land surface models, overland flow, and take advantage of parallelization and high-performance computing (HPC) capabilities; however, they have different approaches to overland subsurface flow and groundwater-surface water interactions. Accurately representing large domains remains a challenge considering the difficult task of representing complex hydrologic processes, computational expense, and extensive data needs; both models have accomplished this, but have differences in approach and continue to be difficult to validate. A further exploration of effective methodology to accurately represent large-scale hydrology with integrated models is needed to advance this growing field. Here we compare the outputs of CONUS-ParFlow and the National Water Model to each other and with observations to study the performance of hyper-resolution models over large domains. Models were compared over a range of scales for major watersheds within the CONUS with a specific focus on the Mississippi, Ohio, and Colorado River basins. We use a novel set of approaches and analysis for this comparison to better understand differences in process and bias. This intercomparison is a step toward better understanding how much water we have and interactions between surface and subsurface. Our goal is to advance our understanding and simulation of the hydrologic system and ultimately improve hydrologic forecasts.

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.

Ma_Miss Experiment: miniaturized imaging spectrometer for subsurface studies

NASA Astrophysics Data System (ADS)

Coradini, A.; Ammannito, E.; Boccaccini, A.; de Sanctis, M. C.; di Iorio, T.; Battistelli, E.; Capanni, A.

2011-10-01

The study of the Martian subsurface will provide important constraints on the nature, timing and duration of alteration and sedimentation processes on Mars, as well as on the complex interactions between the surface and the atmosphere. A Drilling system, coupled with an in situ analysis package, is installed on the Exomars-Pasteur Rover to perform in situ investigations up to 2m in the Mars soil. Ma_Miss (Mars Multispectral Imager for Subsurface Studies) is a spectrometer devoted to observe the lateral wall of the borehole generated by the Drilling system. The instrument is fully integrated with the Drill and shares its structure and electronics.

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.

Geophysical assessment of karst activity

DOT National Transportation Integrated Search

2008-02-01

MST proposes to acquire electrical resistivity data within a pipeline/roadway ROW. These geophysical data will be processed, analyzed and interpreted with the objective of locating and mapping any subsurface voids that might compromise the integrity ...

Different integrated geophysical approaches to investigate archaeological sites in urban and suburban area.

NASA Astrophysics Data System (ADS)

Piro, Salvatore; Papale, Enrico; Zamuner, Daniela

2016-04-01

Geophysical methods are frequently used in archaeological prospection in order to provide detailed information about the presence of structures in the subsurface as well as their position and their geometrical reconstruction, by measuring variations of some physical properties. Often, due to the limited size and depth of an archaeological structure, it may be rather difficult to single out its position and extent because of the generally low signal-to-noise ratio. This problem can be overcome by improving data acquisition, processing techniques and by integrating different geophysical methods. In this work, two sites of archaeological interest, were investigated employing several methods (Ground Penetrating Radar (GPR), Electrical Resistivity Tomography (ERT), Fluxgate Differential Magnetic) to obtain precise and detailed maps of subsurface bodies. The first site, situated in a suburban area between Itri and Fondi, in the Aurunci Natural Regional Park (Central Italy), is characterized by the presence of remains of past human activity dating from the third century B.C. The second site, is instead situated in an urban area in the city of Rome (Basilica di Santa Balbina), where historical evidence is also present. The methods employed, allowed to determine the position and the geometry of some structures in the subsurface related to this past human activity. To have a better understanding of the subsurface, we then performed a qualitative and quantitative integration of this data, which consists in fusing the data from all the methods used, to have a complete visualization of the investigated area. Qualitative integration consists in graphically overlaying the maps obtained by the single methods; this method yields only images, not new data that may be subsequently analyzed. Quantitative integration is instead performed by mathematical and statistical solutions, which allows to have a more accurate reconstruction of the subsurface and generates new data with high information content.

CONSIDERATIONS FOR INNOVATIVE REMEDIATION TECHNOLOGY EVALUATION SAMPLING PLANS

EPA Science Inventory

Field trials of innovative subsurface cleanup technologies require the use of integrated site characterization approaches to obtain critical design parameters, to evaluate pre-treatment contaminant distributions, and to assess process efficiency. This review focuses on the trans...

Integral Analysis of Seismic Refraction and Ambient Vibration Survey for Subsurface Profile Evaluation

NASA Astrophysics Data System (ADS)

Hazreek, Z. A. M.; Kamarudin, A. F.; Rosli, S.; Fauziah, A.; Akmal, M. A. K.; Aziman, M.; Azhar, A. T. S.; Ashraf, M. I. M.; Shaylinda, M. Z. N.; Rais, Y.; Ishak, M. F.; Alel, M. N. A.

2018-04-01

Geotechnical site investigation as known as subsurface profile evaluation is the process of subsurface layer characteristics determination which finally used for design and construction phase. Traditionally, site investigation was performed using drilling technique thus suffers from several limitation due to cost, time, data coverage and sustainability. In order to overcome those problems, this study adopted surface techniques using seismic refraction and ambient vibration method for subsurface profile depth evaluation. Seismic refraction data acquisition and processing was performed using ABEM Terraloc and OPTIM software respectively. Meanwhile ambient vibration data acquisition and processing was performed using CityShark II, Lennartz and GEOPSY software respectively. It was found that studied area consist of two layers representing overburden and bedrock geomaterials based on p-wave velocity value (vp = 300 – 2500 m/s and vp > 2500 m/s) and natural frequency value (Fo = 3.37 – 3.90 Hz) analyzed. Further analysis found that both methods show some good similarity in term of depth and thickness with percentage accuracy at 60 – 97%. Consequently, this study has demonstrated that the application of seismic refractin and ambient vibration method was applicable in subsurface profile depth and thickness estimation. Moreover, surface technique which consider as non-destructive method adopted in this study was able to compliment conventional drilling method in term of cost, time, data coverage and environmental sustainaibility.

Integration of geological remote-sensing techniques in subsurface analysis

USGS Publications Warehouse

Taranik, James V.; Trautwein, Charles M.

1976-01-01

Geological remote sensing is defined as the study of the Earth utilizing electromagnetic radiation which is either reflected or emitted from its surface in wavelengths ranging from 0.3 micrometre to 3 metres. The natural surface of the Earth is composed of a diversified combination of surface cover types, and geologists must understand the characteristics of surface cover types to successfully evaluate remotely-sensed data. In some areas landscape surface cover changes throughout the year, and analysis of imagery acquired at different times of year can yield additional geological information. Integration of different scales of analysis allows landscape features to be effectively interpreted. Interpretation of the static elements displayed on imagery is referred to as an image interpretation. Image interpretation is dependent upon: (1) the geologist's understanding of the fundamental aspects of image formation, and (2.) his ability to detect, delineate, and classify image radiometric data; recognize radiometric patterns; and identify landscape surface characteristics as expressed on imagery. A geologic interpretation integrates surface characteristics of the landscape with subsurface geologic relationships. Development of a geologic interpretation from imagery is dependent upon: (1) the geologist's ability to interpret geomorphic processes from their static surface expression as landscape characteristics on imagery, (2) his ability to conceptualize the dynamic processes responsible for the evolution 6f interpreted geologic relationships (his ability to develop geologic models). The integration of geologic remote-sensing techniques in subsurface analysis is illustrated by development of an exploration model for ground water in the Tucson area of Arizona, and by the development of an exploration model for mineralization in southwest Idaho.

Using in-situ Glider Data to Improve the Interpretation of Time-Series Data in the San Pedro Channel

NASA Astrophysics Data System (ADS)

Teel, E.; Liu, X.; Seegers, B. N.; Ragan, M. A.; Jones, B. H.; Levine, N. M.

2016-02-01

Oceanic time-series have provided insight into biological, physical, and chemical processes and how these processes change over time. However, time-series data collected near coastal zones have not been used as broadly because of regional features that may prevent extrapolation of local results. Though these sites are inherently more affected by local processes, broadening the application of coastal data is crucial for improved modeling of processes such as total carbon drawdown and the development of oxygen minimum zones. Slocum gliders were deployed off the coast of Los Angeles from February to July of 2013 and 2014 providing high temporal and spatial resolution data of the San Pedro Channel (SPC), which includes the San Pedro Ocean Time Series (SPOT). The data were collapsed onto a standardized grid and primary and secondary characteristics of glider profiles were analyzed by principal component analysis to determine the processes impacting SPC and SPOT. The data fell into four categories: active upwelling, offshore intrusion, subsurface bloom, and surface bloom. Waters across the SPC were most similar to offshore water masses, even during the upwelling season when near-shore blooms are commonly observed. The SPOT site was found to be representative of the SPC 86% of the time, suggesting that the findings from SPOT are applicable for the entire SPC. Subsurface blooms were common in both years with co-located chlorophyll and particle maxima, and results suggested that these subsurface blooms contribute significantly to the local primary production. Satellite estimation of integrated chlorophyll was poor, possibly due to the prevalence of subsurface blooms and shallow optical depths during surface blooms. These results indicate that high resolution in-situ glider deployments can be used to determine the spatial domain of coastal time-series data, allowing for broader application of these datasets and greater integration into modeling efforts.

Assessment of karst activity at Springfield Route 60 study site

DOT National Transportation Integrated Search

2008-02-01

MST proposes to acquire electrical resistivity data within a roadway ROW. These geophysical data will be processed, analyzed and interpreted with the objective of locating and mapping any subsurface voids that might compromise the integrity of the pi...

Using an Integrated Hydrologic Model to Assess the Ecohydrological Impacts of Change on a Mountain Headwaters Critical Zone

NASA Astrophysics Data System (ADS)

Collins, C.; Maxwell, R. M.; Visser, A.

2016-12-01

The critical zone is the region of the Earth's crust where hydrogeology, ecology, and climate interact. As many critical zone processes are fundamental, the significance of studying critical zone processes goes beyond understanding the local ecohydrological setting. Therefore studying critical zone governing processes requires an interdisciplinary approach that integrates simulation and observation. In this study, a high-resolution integrated hydrologic model, ParFlow-CLM, was developed for the Providence Creek watershed. Providence Creek is a highly instrumented critical zone observatory (CZO) located in the southern Sierra Nevada Mountains, a region currently experiencing a range of short-term responses (i.e. tree mortality) to a severe four-year drought. Sources of plant water use, pathways and residence times of water through the subsurface are identified using a suite of isotopic signatures and numerical particle tracking. Implications of using a fully coupled integrated hydrologic model accompanied by tracer analysis include better understanding of water partitioning and water storage in the regolith and vegetation water use during drought time conditions. The importance of subsurface storage, plant available water and lateral flow during the 2012-2015 drought to mitigate vegetation stress are addressed and verified against observed tree mortality. The stream flow response to tree mortality in the aftermath of the drought, analogous to the Colorado Mountain Pine Beetle case, provides insight into the potential effects of proposed forest management practices.

Microbiological, Geochemical and Hydrologic Processes Controlling Uranium Mobility: An Integrated Field-Scale Subsurface Research Challenge Site at Rifle, Colorado, Quality Assurance Project Plan

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

Fix, N. J.

The U.S. Department of Energy (DOE) is cleaning up and/or monitoring large, dilute plumes contaminated by metals, such as uranium and chromium, whose mobility and solubility change with redox status. Field-scale experiments with acetate as the electron donor have stimulated metal-reducing bacteria to effectively remove uranium [U(VI)] from groundwater at the Uranium Mill Tailings Site in Rifle, Colorado. The Pacific Northwest National Laboratory and a multidisciplinary team of national laboratory and academic collaborators has embarked on a research proposed for the Rifle site, the object of which is to gain a comprehensive and mechanistic understanding of the microbial factors andmore » associated geochemistry controlling uranium mobility so that DOE can confidently remediate uranium plumes as well as support stewardship of uranium-contaminated sites. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by the Rifle Integrated Field-Scale Subsurface Research Challenge Project.« less

[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.

SEMINAR PUBLICATION: SITE CHARACTERIZATION FOR SUBSURFACE REMEDIATION

EPA Science Inventory

This seminar publication provides a comprehensive approach to site characterization for subsurface remediation. Chapter 1 describes a methodology for integrating site characterization with subsurface remediation. The rest of the handbook is divided into three parts. Part I covers...

Recent developments and emergent challenges in Ecohydrology: Focus on the belowground frontier

NASA Astrophysics Data System (ADS)

Mackay, D. S.

2017-12-01

The broad spectrum of ecohydrology issues touch on many areas of research in hydrology. But what are the emerging themes and challenges that represent the core of ecohydrology as a maturing discipline? To answer this question the ecohydrology lens was applied to manuscripts published in Water Resources Research over period of 2015 through July 2017. The 235 manuscripts retrieved can be broadly grouped into catchment hydrology, riparian-hyporheic-stream processes, critical zone, land-atmosphere exchange, wetlands, and sustainability. Three dominant crosscutting themes (i.e., coevolution, interfaces, and energy exchange) account for more than half the papers retrieved. In the context of ecohydrology, coevolution refers to the development of physical systems in concert with biological systems and their interactions. In an ecohydrology context, interfaces refer to subsurface, and sometime surface connections that influence transport (e.g., solutes concentration-discharge) influenced by vegetative plumbing, ecophysiology, animal behavior, and microbial processes. Energy exchange in ecohydrology connects vegetative processes to movement of water to the atmosphere through evapotranspiration. Across these themes there is emerging theory and methodology that emphasizes the integrated roles of biology and hydrology in the subsurface. In particular, there is a notable surge of interest in the role of plant roots on subsurface processes. But these are hard to observe and remain challenging to model. By adopting principles of coevolution, in particular, significant advances will be made in modeling plant roots and their depths, corroborated with new geophysical and tracer tools, for improving understanding of critical zone development, subsurface flow processes, and land-atmosphere energy exchange.

iTOUGH2: A multiphysics simulation-optimization framework for analyzing subsurface systems

NASA Astrophysics Data System (ADS)

Finsterle, S.; Commer, M.; Edmiston, J. K.; Jung, Y.; Kowalsky, M. B.; Pau, G. S. H.; Wainwright, H. M.; Zhang, Y.

2017-11-01

iTOUGH2 is a simulation-optimization framework for the TOUGH suite of nonisothermal multiphase flow models and related simulators of geophysical, geochemical, and geomechanical processes. After appropriate parameterization of subsurface structures and their properties, iTOUGH2 runs simulations for multiple parameter sets and analyzes the resulting output for parameter estimation through automatic model calibration, local and global sensitivity analyses, data-worth analyses, and uncertainty propagation analyses. Development of iTOUGH2 is driven by scientific challenges and user needs, with new capabilities continually added to both the forward simulator and the optimization framework. This review article provides a summary description of methods and features implemented in iTOUGH2, and discusses the usefulness and limitations of an integrated simulation-optimization workflow in support of the characterization and analysis of complex multiphysics subsurface systems.

Integrated Experimental and Computational Study of Hydraulic Fracturing and the Use of Alternative Fracking Fluids

NASA Astrophysics Data System (ADS)

Viswanathan, H.; Carey, J. W.; Karra, S.; Porter, M. L.; Rougier, E.; Zhang, D.; Makedonska, N.; Middleton, R. S.; Currier, R.; Gupta, R.; Lei, Z.; Kang, Q.; O'Malley, D.; Hyman, J.

2014-12-01

Shale gas is an unconventional fossil energy resource that is already having a profound impact on US energy independence and is projected to last for at least 100 years. Production of methane and other hydrocarbons from low permeability shale involves hydrofracturing of rock, establishing fracture connectivity, and multiphase fluid-flow and reaction processes all of which are poorly understood. The result is inefficient extraction with many environmental concerns. A science-based capability is required to quantify the governing mesoscale fluid-solid interactions, including microstructural control of fracture patterns and the interaction of engineered fluids with hydrocarbon flow. These interactions depend on coupled thermo-hydro-mechanical-chemical (THMC) processes over scales from microns to tens of meters. Determining the key mechanisms in subsurface THMC 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. This project uses innovative high-pressure microfluidic and triaxial core flood experiments on shale to explore fracture-permeability relations and the extraction of hydrocarbon. These data are integrated with simulations including lattice Boltzmann modeling of pore-scale processes, finite-element/discrete element models of fracture development in the near-well environment, discrete-fracture modeling of the reservoir, and system-scale models to assess the economics of alternative fracturing fluids. The ultimate goal is to make the necessary measurements to develop models that can be used to determine the reservoir operating conditions necessary to gain a degree of control over fracture generation, fluid flow, and interfacial processes over a range of subsurface conditions.

Lights Out Operations of a Space, Ground, Sensorweb

NASA Technical Reports Server (NTRS)

Chien, Steve; Tran, Daniel; Johnston, Mark; Davies, Ashley Gerard; Castano, Rebecca; Rabideau, Gregg; Cichy, Benjamin; Doubleday, Joshua; Pieri, David; Scharenbroich, Lucas;

Integration of Magnetic and Geotechnical methods for Shallow Subsurface Soil Characterization at Sungai Batu, Kedah, Malaysia

NASA Astrophysics Data System (ADS)

Samuel, Y. M.; Saad, R.; Muztaza, N. M.; Saidin, M. M.; Muhammad, S. B.

2018-04-01

Magnetic and geotechnical methods were used for shallow subsurface soil characterization at Sungai Batu, Kedah, (Malaysia). Ground magnetic data were collected along a survey line of length 160 m long at 2 m constant station spacing, while soil drilling using hand auger was conducted at 21 m on the survey line using 0.2 m sampling interval drilled to a depth of 5 m. Result from the processed magnetic profile data shows distribution of magnetic residuals in the range of -4.55 to 1.61 nT, with magnetic low (-4.55 nT to -0.058 nT) and were identified at distances 4 m, 10 to 16 m, 20 to 26 m, 58 m, 82 m, 104 to 106 m, 118 m, and 124 to 140 m. The magnetic lows are attributes of sediments. The result from the soil drilling shows sticky samples with variable sizes, greyish to brownish / reddish in colour, and some of the samples show the presence of shiny and black spots. The characteristics of the samples suggest the soil as a by-product of completely weathered rock; weak with high water content and classified as Grade V soil. The study concludes; integration of geophysical and geotechnical methods aided in characterizing the subsurface soil at Sungai Batu. The result was correlated with previous studies and confirms the importance of integrated approach in minimising ambiguity in interpretation.

Quantifying wetland–aquifer interactions in a humid subtropical climate region: An integrated approach

USGS Publications Warehouse

Mendoza-Sanchez, Itza; Phanikumar, Mantha S.; Niu, Jie; Masoner, Jason R.; Cozzarelli, Isabelle M.; McGuire, Jennifer T.

2013-01-01

Wetlands are widely recognized as sentinels of global climate change. Long-term monitoring data combined with process-based modeling has the potential to shed light on key processes and how they change over time. This paper reports the development and application of a simple water balance model based on long-term climate, soil, vegetation and hydrological dynamics to quantify groundwater–surface water (GW–SW) interactions at the Norman landfill research site in Oklahoma, USA. Our integrated approach involved model evaluation by means of the following independent measurements: (a) groundwater inflow calculation using stable isotopes of oxygen and hydrogen (16O, 18O, 1H, 2H); (b) seepage flux measurements in the wetland hyporheic sediment; and (c) pan evaporation measurements on land and in the wetland. The integrated approach was useful for identifying the dominant hydrological processes at the site, including recharge and subsurface flows. Simulated recharge compared well with estimates obtained using isotope methods from previous studies and allowed us to identify specific annual signatures of this important process during the period of study (1997–2007). Similarly, observations of groundwater inflow and outflow rates to and from the wetland using seepage meters and isotope methods were found to be in good agreement with simulation results. Results indicate that subsurface flow components in the system are seasonal and readily respond to rainfall events. The wetland water balance is dominated by local groundwater inputs and regional groundwater flow contributes little to the overall water balance.

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

PubMed

Bagnoud, Alexandre; Chourey, Karuna; Hettich, Robert L; de Bruijn, Ino; Andersson, Anders F; Leupin, Olivier X; Schwyn, Bernhard; Bernier-Latmani, Rizlan

2016-10-14

The Opalinus Clay formation will host geological nuclear waste repositories in Switzerland. It is expected that gas pressure will build-up due to hydrogen production from steel corrosion, jeopardizing the integrity of the engineered barriers. In an in situ experiment located in the Mont Terri Underground Rock Laboratory, we demonstrate that hydrogen is consumed by microorganisms, fuelling a microbial community. Metagenomic binning and metaproteomic analysis of this deep subsurface community reveals a carbon cycle driven by autotrophic hydrogen oxidizers belonging to novel genera. Necromass is then processed by fermenters, followed by complete oxidation to carbon dioxide by heterotrophic sulfate-reducing bacteria, which closes the cycle. This microbial metabolic web can be integrated in the design of geological repositories to reduce pressure build-up. This study shows that Opalinus Clay harbours the potential for chemolithoautotrophic-based system, and provides a model of microbial carbon cycle in deep subsurface environments where hydrogen and sulfate are present.

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

PubMed Central

Bagnoud, Alexandre; Chourey, Karuna; Hettich, Robert L.; de Bruijn, Ino; Andersson, Anders F.; Leupin, Olivier X.; Schwyn, Bernhard; Bernier-Latmani, Rizlan

2016-01-01

The Opalinus Clay formation will host geological nuclear waste repositories in Switzerland. It is expected that gas pressure will build-up due to hydrogen production from steel corrosion, jeopardizing the integrity of the engineered barriers. In an in situ experiment located in the Mont Terri Underground Rock Laboratory, we demonstrate that hydrogen is consumed by microorganisms, fuelling a microbial community. Metagenomic binning and metaproteomic analysis of this deep subsurface community reveals a carbon cycle driven by autotrophic hydrogen oxidizers belonging to novel genera. Necromass is then processed by fermenters, followed by complete oxidation to carbon dioxide by heterotrophic sulfate-reducing bacteria, which closes the cycle. This microbial metabolic web can be integrated in the design of geological repositories to reduce pressure build-up. This study shows that Opalinus Clay harbours the potential for chemolithoautotrophic-based system, and provides a model of microbial carbon cycle in deep subsurface environments where hydrogen and sulfate are present. PMID:27739431

Some Ecological Mechanisms to Generate Habitability in Planetary Subsurface Areas by Chemolithotrophic Communities: The Ro Tinto Subsurface Ecosystem as a Model System

NASA Astrophysics Data System (ADS)

Fernández-Remolar, David C.; Gómez, Felipe; Prieto-Ballesteros, Olga; Schelble, Rachel T.; Rodríguez, Nuria; Amiols, Ricardo

2008-02-01

Chemolithotrophic communities that colonize subsurface habitats have great relevance for the astrobiological exploration of our Solar System. We hypothesize that the chemical and thermal stabilization of an environment through microbial activity could make a given planetary region habitable. The MARTE project ground-truth drilling campaigns that sampled cryptic subsurface microbial communities in the basement of the Ro Tinto headwaters have shown that acidic surficial habitats are the result of the microbial oxidation of pyritic ores. The oxidation process is exothermic and releases heat under both aerobic and anaerobic conditions. These microbial communities can maintain the subsurface habitat temperature through storage heat if the subsurface temperature does not exceed their maximum growth temperature. In the acidic solutions of the Ro Tinto, ferric iron acts as an effective buffer for controlling water pH. Under anaerobic conditions, ferric iron is the oxidant used by microbes to decompose pyrite through the production of sulfate, ferrous iron, and protons. The integration between the physical and chemical processes mediated by microorganisms with those driven by the local geology and hydrology have led us to hypothesize that thermal and chemical regulation mechanisms exist in this environment and that these homeostatic mechanisms could play an essential role in creating habitable areas for other types of microorganisms. Therefore, searching for the physicochemical expression of extinct and extant homeostatic mechanisms through physical and chemical anomalies in the Mars crust (i.e., local thermal gradient or high concentration of unusual products such as ferric sulfates precipitated out from acidic solutions produced by hypothetical microbial communities) could be a first step in the search for biological traces of a putative extant or extinct Mars biosphere.

Some ecological mechanisms to generate habitability in planetary subsurface areas by chemolithotrophic communities: the Río Tinto subsurface ecosystem as a model system.

PubMed

Fernández-Remolar, David C; Gómez, Felipe; Prieto-Ballesteros, Olga; Schelble, Rachel T; Rodríguez, Nuria; Amils, Ricardo

2008-02-01

Chemolithotrophic communities that colonize subsurface habitats have great relevance for the astrobiological exploration of our Solar System. We hypothesize that the chemical and thermal stabilization of an environment through microbial activity could make a given planetary region habitable. The MARTE project ground-truth drilling campaigns that sampled cryptic subsurface microbial communities in the basement of the Río Tinto headwaters have shown that acidic surficial habitats are the result of the microbial oxidation of pyritic ores. The oxidation process is exothermic and releases heat under both aerobic and anaerobic conditions. These microbial communities can maintain the subsurface habitat temperature through storage heat if the subsurface temperature does not exceed their maximum growth temperature. In the acidic solutions of the Río Tinto, ferric iron acts as an effective buffer for controlling water pH. Under anaerobic conditions, ferric iron is the oxidant used by microbes to decompose pyrite through the production of sulfate, ferrous iron, and protons. The integration between the physical and chemical processes mediated by microorganisms with those driven by the local geology and hydrology have led us to hypothesize that thermal and chemical regulation mechanisms exist in this environment and that these homeostatic mechanisms could play an essential role in creating habitable areas for other types of microorganisms. Therefore, searching for the physicochemical expression of extinct and extant homeostatic mechanisms through physical and chemical anomalies in the Mars crust (i.e., local thermal gradient or high concentration of unusual products such as ferric sulfates precipitated out from acidic solutions produced by hypothetical microbial communities) could be a first step in the search for biological traces of a putative extant or extinct Mars biosphere.

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

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

Complete genome sequence of Anaeromyxobacter sp. Fw109-5, an Anaerobic, Metal-Reducing Bacterium Isolated from a Contaminated Subsurface Environment

DOE PAGES

Hwang, C.; Copeland, A.; Lucas, Susan; ...

2015-01-22

We report the genome sequence of Anaeromyxobacter sp. Fw109-5, isolated from nitrate- and uranium-contaminated subsurface sediment of the Oak Ridge Integrated Field-Scale Subsurface Research Challenge (IFC) site, Oak Ridge Reservation, TN. The bacterium’s genome sequence will elucidate its physiological potential in subsurface sediments undergoing in situ uranium bioremediation and natural attenuation.

Developing a trend prediction model of subsurface damage for fixed-abrasive grinding of optics by cup wheels.

PubMed

Dong, Zhichao; Cheng, Haobo

2016-11-10

Fixed-abrasive grinding by cup wheels plays an important role in the production of precision optics. During cup wheel grinding, we strive for a large removal rate while maintaining fine integrity on the surface and subsurface layers (academically recognized as surface roughness and subsurface damage, respectively). This study develops a theoretical model used to predict the trend of subsurface damage of optics (with respect to various grinding parameters) in fixed-abrasive grinding by cup wheels. It is derived from the maximum undeformed chip thickness model, and it successfully correlates the pivotal parameters of cup wheel grinding with the subsurface damage depth. The efficiency of this model is then demonstrated by a set of experiments performed on a cup wheel grinding machine. In these experiments, the characteristics of subsurface damage are inspected by a wedge-polishing plus microscopic inspection method, revealing that the subsurface damage induced in cup wheel grinding is composed of craterlike morphologies and slender cracks, with depth ranging from ∼6.2 to ∼13.2  μm under the specified grinding parameters. With the help of the proposed model, an optimized grinding strategy is suggested for realizing fine subsurface integrity as well as high removal rate, which can alleviate the workload of subsequent lapping and polishing.

A Mobile Acoustic Subsurface Sensing (MASS) System for Rapid Roadway Assessment

PubMed Central

Lu, Yifeng; Zhang, Yi; Cao, Yinghong; McDaniel, J. Gregory; Wang, Ming L.

2013-01-01

Surface waves are commonly used for vibration-based nondestructive testing for infrastructure. Spectral Analysis of Surface Waves (SASW) has been used to detect subsurface properties for geologic inspections. Recently, efforts were made to scale down these subsurface detection approaches to see how they perform on small-scale structures such as concrete slabs and pavements. Additional efforts have been made to replace the traditional surface-mounted transducers with non-contact acoustic transducers. Though some success has been achieved, most of these new approaches are inefficient because they require point-to-point measurements or off-line signal analysis. This article introduces a Mobile Acoustic Subsurface Sensing system as MASS, which is an improved surface wave based implementation for measuring the subsurface profile of roadways. The compact MASS system is a 3-wheeled cart outfitted with an electromagnetic impact source, distance register, non-contact acoustic sensors and data acquisition/processing equipment. The key advantage of the MASS system is the capability to collect measurements continuously at walking speed in an automatic way. The fast scan and real-time analysis advantages are based upon the non-contact acoustic sensing and fast air-coupled surface wave analysis program. This integration of hardware and software makes the MASS system an efficient mobile prototype for the field test. PMID:23698266

Automated assessment of the remineralization of artificial enamel lesions with polarization-sensitive optical coherence tomography

PubMed Central

Lee, Robert C.; Kang, Hobin; Darling, Cynthia L.; Fried, Daniel

2014-01-01

Accurate measurement of the highly mineralized transparent surface layer that forms on caries lesions is important for diagnosis of the lesion activity because chemical intervention can slow or reverse the caries process via remineralization. Previous in-vitro and in-vivo studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can nondestructively image the subsurface lesion structure and the highly mineralized transparent surface zone of caries lesions. The purpose of this study was to develop an approach to automatically process 3-dimensional PS-OCT images and to accurately assess the remineralization process in simulated enamel lesions. Artificial enamel lesions were prepared on twenty bovine enamel blocks using two models to produce varying degree of demineralization and remineralization. The thickness of the transparent surface layer and the integrated reflectivity of the subsurface lesion were measured using PS-OCT. The automated transparent surface layer detection algorithm was able to successfully detect the transparent surface layers with high sensitivity ( = 0.92) and high specificity ( = 0.97). The estimated thickness of the transparent surface layer showed a strong correlation with polarized light microscopy (PLM) measurements of all regions (R2 = 0.90). The integrated reflectivity, ΔR, and the integrated mineral loss, ΔZ, showed a moderate correlation (R2 = 0.32). This study demonstrates that PS-OCT can automatically measure the changes in artificial enamel lesion structure and severity upon exposure to remineralization solutions. PMID:25401009

Dynamics of nonreactive solute transport in the permafrost environment

NASA Astrophysics Data System (ADS)

Svyatskiy, D.; Coon, E. T.; Moulton, J. D.

2017-12-01

As part of the DOE Office of Science Next Generation Ecosystem Experiment, NGEE-Arctic, researchers are developing process-rich models to understand and predict the evolution of water sources and hydrologic flow pathways resulting from degrading permafrost. The sources and interaction of surface and subsurface water and flow paths are complex in space and time due to strong interplay between heterogeneous subsurface parameters, the seasonal to decadal evolution of the flow domain, climate driven melting and release of permafrost ice as a liquid water source, evolving surface topography and highly variable meteorological data. In this study, we seek to characterize the magnitude of vertical and lateral subsurface flows in a cold, wet tundra, polygonal landscape characteristic of the Barrow Peninsula, AK. To better understand the factors controlling water flux partitioning in these low gradient landscapes, NGEE researchers developed and are applying the Advanced Terrestrial Simulator (ATS), which fully couples surface and subsurface flow and energy processes, snow distribution and atmospheric forcing. Here we demonstrate the integration of a new solute transport model within the ATS, which enables the interpretation of applied and natural tracer experiments and observations aimed at quantifying water sources and flux partitioning. We examine the role of ice wedge polygon structure, freeze-thaw processes and soil properties on the seasonal transport of water within and through polygons features, and compare results to tracer experiments on 2D low-centered and high-centered transects corresponding to artificial as well as realistic topographical data from sites in polygonal tundra. These simulations demonstrate significant difference between flow patterns between permafrost and non-permafrost environments due to active layer freeze-thaw processes.

Degradation of benzotriazole and benzothiazole in treatment wetlands and by artificial sunlight.

PubMed

Felis, Ewa; Sochacki, Adam; Magiera, Sylwia

2016-11-01

Laboratory-scale experiments were performed using unsaturated subsurface-flow treatment wetlands and artificial sunlight (with and without TiO 2 ) to study the efficiency of benzotriazole and benzothiazole removal and possible integration of these treatment methods. Transformation products in the effluent from the treatment wetlands and the artificial sunlight reactor were identified by high performance liquid chromatography coupled with tandem mass spectrometry. The removal of benzothiazole in the vegetated treatment wetlands was 99.7%, whereas the removal of benzotriazole was 82.8%. The vegetation positively affected only the removal of benzothiazole. The major transformation products in the effluents from the treatment wetlands were methylated and hydroxylated derivatives of benzotriazole, and hydroxylated derivatives of benzothiazole. Hydroxylation was found to be the main process governing the transformation pathway for both compounds in the artificial sunlight experiment (with and without TiO 2 ). Benzotriazole was not found to be susceptible to photodegradation in the absence of TiO 2 . The integration of the sunlight-induced processes (with TiO 2 ) with subsurface-flow treatment wetlands caused further elimination of the compounds (42% for benzotriazole and 58% for benzothiazole). This was especially significant for the elimination of benzotriazole, because the removal of this compound was 96% in the coupled processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Upper ocean climate of the Eastern Mediterranean Sea during the Holocene Insolation Maximum - a model study

NASA Astrophysics Data System (ADS)

Adloff, F.; Mikolajewicz, U.; Kučera, M.; Grimm, R.; Maier-Reimer, E.; Schmiedl, G.; Emeis, K.-C.

2011-10-01

Nine thousand years ago (9 ka BP), the Northern Hemisphere experienced enhanced seasonality caused by an orbital configuration close to the minimum of the precession index. To assess the impact of this "Holocene Insolation Maximum" (HIM) on the Mediterranean Sea, we use a regional ocean general circulation model forced by atmospheric input derived from global simulations. A stronger seasonal cycle is simulated by the model, which shows a relatively homogeneous winter cooling and a summer warming with well-defined spatial patterns, in particular, a subsurface warming in the Cretan and western Levantine areas. The comparison between the SST simulated for the HIM and a reconstruction from planktonic foraminifera transfer functions shows a poor agreement, especially for summer, when the vertical temperature gradient is strong. As a novel approach, we propose a reinterpretation of the reconstruction, to consider the conditions throughout the upper water column rather than at a single depth. We claim that such a depth-integrated approach is more adequate for surface temperature comparison purposes in a situation where the upper ocean structure in the past was different from the present-day. In this case, the depth-integrated interpretation of the proxy data strongly improves the agreement between modelled and reconstructed temperature signal with the subsurface summer warming being recorded by both model and proxies, with a small shift to the south in the model results. The mechanisms responsible for the peculiar subsurface pattern are found to be a combination of enhanced downwelling and wind mixing due to strengthened Etesian winds, and enhanced thermal forcing due to the stronger summer insolation in the Northern Hemisphere. Together, these processes induce a stronger heat transfer from the surface to the subsurface during late summer in the western Levantine; this leads to an enhanced heat piracy in this region, a process never identified before, but potentially characteristic of time slices with enhanced insolation.

Corrigendum to "Upper ocean climate of the Eastern Mediterranean Sea during the Holocene Insolation Maximum - a model study" published in Clim. Past, 7, 1103-1122, 2011

NASA Astrophysics Data System (ADS)

Adloff, F.; Mikolajewicz, U.; Kučera, M.; Grimm, R.; Maier-Reimer, E.; Schmiedl, G.; Emeis, K.-C.

2011-11-01

Nine thousand years ago (9 ka BP), the Northern Hemisphere experienced enhanced seasonality caused by an orbital configuration close to the minimum of the precession index. To assess the impact of this "Holocene Insolation Maximum" (HIM) on the Mediterranean Sea, we use a regional ocean general circulation model forced by atmospheric input derived from global simulations. A stronger seasonal cycle is simulated by the model, which shows a relatively homogeneous winter cooling and a summer warming with well-defined spatial patterns, in particular, a subsurface warming in the Cretan and western Levantine areas. The comparison between the SST simulated for the HIM and a reconstruction from planktonic foraminifera transfer functions shows a poor agreement, especially for summer, when the vertical temperature gradient is strong. As a novel approach, we propose a reinterpretation of the reconstruction, to consider the conditions throughout the upper water column rather than at a single depth. We claim that such a depth-integrated approach is more adequate for surface temperature comparison purposes in a situation where the upper ocean structure in the past was different from the present-day. In this case, the depth-integrated interpretation of the proxy data strongly improves the agreement between modelled and reconstructed temperature signal with the subsurface summer warming being recorded by both model and proxies, with a small shift to the south in the model results. The mechanisms responsible for the peculiar subsurface pattern are found to be a combination of enhanced downwelling and wind mixing due to strengthened Etesian winds, and enhanced thermal forcing due to the stronger summer insolation in the Northern Hemisphere. Together, these processes induce a stronger heat transfer from the surface to the subsurface during late summer in the western Levantine; this leads to an enhanced heat piracy in this region, a process never identified before, but potentially characteristic of time slices with enhanced insolation.

Spectral measurements of Terrestrial Mars Analogues: support for the ExoMars - Ma_Miss instrument

NASA Astrophysics Data System (ADS)

De Angelis, S.; De Sanctis, M. C.; Ammannito, E.; Di Iorio, T.; Carli, C.; Frigeri, A.; Capria, M. T.; Federico, C.; Boccaccini, A.; Capaccioni, F.; Giardino, M.; Cerroni, P.; Palomba, E.; Piccioni, G.

2013-09-01

The Ma_Miss (Mars Multispectral Imager for Subsurface Studies) instrument onboard of ExoMars 2018 mission to Mars will investigate the Martian subsoil down to a depth of 2 meters [1]. Ma_Miss is a miniaturized spectrometer, completely integrated within the drilling system of the ExoMars Pasteur rover; it will acquire spectra in the range 0.4-2.2μm, from the excavated borehole wall. The spectroscopic investigation of the subsurface materials will give us precious information about mineralogical, petrologic and geological processes, and will give insights about materials that have not been modified by surface processes such as erosion, weathering or oxidation. Spectroscopic measurements have been performed on Terrestrial Mars Analogues with the Ma_Miss laboratory model (breadboard). Moreover spectroscopic investigation of different sets of Terrestrial Mars Analogues is being carried on with different laboratory setups, as a support for the ExoMars-Ma_Miss instrument.

Influence of cutting parameters on the depth of subsurface deformed layer in nano-cutting process of single crystal copper.

PubMed

Wang, Quanlong; Bai, Qingshun; Chen, Jiaxuan; Su, Hao; Wang, Zhiguo; Xie, Wenkun

2015-12-01

Large-scale molecular dynamics simulation is performed to study the nano-cutting process of single crystal copper realized by single-point diamond cutting tool in this paper. The centro-symmetry parameter is adopted to characterize the subsurface deformed layers and the distribution and evolution of the subsurface defect structures. Three-dimensional visualization and measurement technology are used to measure the depth of the subsurface deformed layers. The influence of cutting speed, cutting depth, cutting direction, and crystallographic orientation on the depth of subsurface deformed layers is systematically investigated. The results show that a lot of defect structures are formed in the subsurface of workpiece during nano-cutting process, for instance, stair-rod dislocations, stacking fault tetrahedron, atomic clusters, vacancy defects, point defects. In the process of nano-cutting, the depth of subsurface deformed layers increases with the cutting distance at the beginning, then decreases at stable cutting process, and basically remains unchanged when the cutting distance reaches up to 24 nm. The depth of subsurface deformed layers decreases with the increase in cutting speed between 50 and 300 m/s. The depth of subsurface deformed layer increases with cutting depth, proportionally, and basically remains unchanged when the cutting depth reaches over 6 nm.

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 stochastic approach for model reduction and memory function design in hydrogeophysical inversion

NASA Astrophysics Data System (ADS)

Hou, Z.; Kellogg, A.; Terry, N.

2009-12-01

Geophysical (e.g., seismic, electromagnetic, radar) techniques and statistical methods are essential for research related to subsurface characterization, including monitoring subsurface flow and transport processes, oil/gas reservoir identification, etc. For deep subsurface characterization such as reservoir petroleum exploration, seismic methods have been widely used. Recently, electromagnetic (EM) methods have drawn great attention in the area of reservoir characterization. However, considering the enormous computational demand corresponding to seismic and EM forward modeling, it is usually a big problem to have too many unknown parameters in the modeling domain. For shallow subsurface applications, the characterization can be very complicated considering the complexity and nonlinearity of flow and transport processes in the unsaturated zone. It is warranted to reduce the dimension of parameter space to a reasonable level. Another common concern is how to make the best use of time-lapse data with spatial-temporal correlations. This is even more critical when we try to monitor subsurface processes using geophysical data collected at different times. The normal practice is to get the inverse images individually. These images are not necessarily continuous or even reasonably related, because of the non-uniqueness of hydrogeophysical inversion. We propose to use a stochastic framework by integrating minimum-relative-entropy concept, quasi Monto Carlo sampling techniques, and statistical tests. The approach allows efficient and sufficient exploration of all possibilities of model parameters and evaluation of their significances to geophysical responses. The analyses enable us to reduce the parameter space significantly. The approach can be combined with Bayesian updating, allowing us to treat the updated ‘posterior’ pdf as a memory function, which stores all the information up to date about the distributions of soil/field attributes/properties, then consider the memory function as a new prior and generate samples from it for further updating when more geophysical data is available. We applied this approach for deep oil reservoir characterization and for shallow subsurface flow monitoring. The model reduction approach reliably helps reduce the joint seismic/EM/radar inversion computational time to reasonable levels. Continuous inversion images are obtained using time-lapse data with the “memory function” applied in the Bayesian inversion.

Surface and subsurface continuous gravimetric monitoring of groundwater recharge processes through the karst vadose zone at Rochefort Cave (Belgium)

NASA Astrophysics Data System (ADS)

Watlet, A.; Van Camp, M. J.; Francis, O.; Poulain, A.; Hallet, V.; Triantafyllou, A.; Delforge, D.; Quinif, Y.; Van Ruymbeke, M.; Kaufmann, O.

2017-12-01

Ground-based gravimetry is a non-invasive and integrated tool to characterize hydrological processes in complex environments such as karsts or volcanoes. A problem in ground-based gravity measurements however concerns the lack of sensitivity in the first meters below the topographical surface, added to limited infiltration below the gravimeter building (umbrella effect). Such limitations disappear when measuring underground. Coupling surface and subsurface gravity measurements therefore allow isolating hydrological signals occurring in the zone between the two gravimeters. We present a coupled surface/subsurface continuous gravimetric monitoring of 2 years at the Rochefort Cave Laboratory (Belgium). The gravity record includes surface measurements of a GWR superconducting gravimeter and subsurface measurements of a Micro-g LaCoste gPhone gravimeter, installed in a cave 35 m below the surface station. The recharge of karstic aquifers is extremely complex to model, mostly because karst hydrological systems are composed of strongly heterogeneous flows. Most of the problem comes from the inadequacy of conventional measuring tools to correctly sample such heterogeneous media, and particularly the existence of a duality of flow types infiltrating the vadose zone: from rapid flows via open conduits to slow seepage through porous matrix. Using the surface/subsurface gravity difference, we were able to identify a significant seasonal groundwater recharge within the karst vadose zone. Seasonal or perennial perched reservoirs have already been proven to exist in several karst areas due to the heterogeneity of the porosity and permeability gradient in karstified carbonated rocks. Our gravimetric experiment allows assessing more precisely the recharge processes of such reservoirs. The gravity variations were also compared with surface and in-cave hydrogeological monitoring (i.e. soil moisture, in-cave percolating water discharges, water levels of the saturated zone). Combined with additional geological information, modeling of the gravity signal based on the vertical component of the gravitational attraction was particularly useful to estimate the seasonal recharge leading to temporary groundwater storage in the vadose zone.

Introduction of the 2nd Phase of the Integrated Hydrologic Model Intercomparison Project

NASA Astrophysics Data System (ADS)

Kollet, Stefan; Maxwell, Reed; Dages, Cecile; Mouche, Emmanuel; Mugler, Claude; Paniconi, Claudio; Park, Young-Jin; Putti, Mario; Shen, Chaopeng; Stisen, Simon; Sudicky, Edward; Sulis, Mauro; Ji, Xinye

2015-04-01

The 2nd Phase of the Integrated Hydrologic Model Intercomparison Project commenced in June 2013 with a workshop at Bonn University funded by the German Science Foundation and US National Science Foundation. Three test cases were defined and compared that are available online at www.hpsc-terrsys.de including a tilted v-catchment case; a case called superslab based on multiple slab-heterogeneities in the hydraulic conductivity along a hillslope; and the Borden site case, based on a published field experiment. The goal of this phase is to further interrogate the coupling of surface-subsurface flow implemented in various integrated hydrologic models; and to understand and quantify the impact of differences in the conceptual and technical implementations on the simulation results, which may constitute an additional source of uncertainty. The focus has been broadened considerably including e.g. saturated and unsaturated subsurface storages, saturated surface area, ponded surface storage in addition to discharge, and pressure/saturation profiles and cross-sections. Here, first results are presented and discussed demonstrating the conceptual and technical challenges in implementing essentially the same governing equations describing highly non-linear moisture redistribution processes and surface-groundwater interactions.

TOUGH2Biot - A simulator for coupled thermal-hydrodynamic-mechanical processes in subsurface flow systems: Application to CO2 geological storage and geothermal development

NASA Astrophysics Data System (ADS)

Lei, Hongwu; Xu, Tianfu; Jin, Guangrong

2015-04-01

Coupled thermal-hydrodynamic-mechanical processes have become increasingly important in studying the issues affecting subsurface flow systems, such as CO2 sequestration in deep saline aquifers and geothermal development. In this study, a mechanical module based on the extended Biot consolidation model was developed and incorporated into the well-established thermal-hydrodynamic simulator TOUGH2, resulting in an integrated numerical THM simulation program TOUGH2Biot. A finite element method was employed to discretize space for rock mechanical calculation and the Mohr-Coulomb failure criterion was used to determine if the rock undergoes shear-slip failure. Mechanics is partly coupled with the thermal-hydrodynamic processes and gives feedback to flow through stress-dependent porosity and permeability. TOUGH2Biot was verified against analytical solutions for the 1D Terzaghi consolidation and cooling-induced subsidence. TOUGH2Biot was applied to evaluate the thermal, hydrodynamic, and mechanical responses of CO2 geological sequestration at the Ordos CCS Demonstration Project, China and geothermal exploitation at the Geysers geothermal field, California. The results demonstrate that TOUGH2Biot is capable of analyzing change in pressure and temperature, displacement, stress, and potential shear-slip failure caused by large scale underground man-made activity in subsurface flow systems. TOUGH2Biot can also be easily extended for complex coupled process problems in fractured media and be conveniently updated to parallel versions on different platforms to take advantage of high-performance computing.

Sub-surface defects detection of by using active thermography and advanced image edge detection

NASA Astrophysics Data System (ADS)

Tse, Peter W.; Wang, Gaochao

2017-05-01

Active or pulsed thermography is a popular non-destructive testing (NDT) tool for inspecting the integrity and anomaly of industrial equipment. One of the recent research trends in using active thermography is to automate the process in detecting hidden defects. As of today, human effort has still been using to adjust the temperature intensity of the thermo camera in order to visually observe the difference in cooling rates caused by a normal target as compared to that by a sub-surface crack exists inside the target. To avoid the tedious human-visual inspection and minimize human induced error, this paper reports the design of an automatic method that is capable of detecting subsurface defects. The method used the technique of active thermography, edge detection in machine vision and smart algorithm. An infrared thermo-camera was used to capture a series of temporal pictures after slightly heating up the inspected target by flash lamps. Then the Canny edge detector was employed to automatically extract the defect related images from the captured pictures. The captured temporal pictures were preprocessed by a packet of Canny edge detector and then a smart algorithm was used to reconstruct the whole sequences of image signals. During the processes, noise and irrelevant backgrounds exist in the pictures were removed. Consequently, the contrast of the edges of defective areas had been highlighted. The designed automatic method was verified by real pipe specimens that contains sub-surface cracks. After applying such smart method, the edges of cracks can be revealed visually without the need of using manual adjustment on the setting of thermo-camera. With the help of this automatic method, the tedious process in manually adjusting the colour contract and the pixel intensity in order to reveal defects can be avoided.

Magnetorheological finishing for removing surface and subsurface defects of fused silica optics

NASA Astrophysics Data System (ADS)

Catrin, Rodolphe; Neauport, Jerome; Taroux, Daniel; Cormont, Philippe; Maunier, Cedric; Lambert, Sebastien

2014-09-01

We investigate the capacity of magnetorheological finishing (MRF) process to remove surface and subsurface defects of fused silica optics. Polished samples with engineered surface and subsurface defects were manufactured and characterized. Uniform material removals were performed with a QED Q22-XE machine using different MRF process parameters in order to remove these defects. We provide evidence that whatever the MRF process parameters are, MRF is able to remove surface and subsurface defects. Moreover, we show that MRF induces a pollution of the glass interface similar to conventional polishing processes.

Modeling alpine grasslands with two integrated hydrologic models: a comparison of the different process representation in CATHY and GEOtop

NASA Astrophysics Data System (ADS)

Camporese, M.; Bertoldi, G.; Bortoli, E.; Wohlfahrt, G.

2017-12-01

Integrated hydrologic surface-subsurface models (IHSSMs) are increasingly used as prediction tools to solve simultaneously states and fluxes in and between multiple terrestrial compartments (e.g., snow cover, surface water, groundwater), in an attempt to tackle environmental problems in a holistic approach. Two such models, CATHY and GEOtop, are used in this study to investigate their capabilities to reproduce hydrological processes in alpine grasslands. The two models differ significantly in the complexity of the representation of the surface energy balance and the solution of Richards equation for water flow in the variably saturated subsurface. The main goal of this research is to show how these differences in process representation can lead to different predictions of hydrologic states and fluxes, in the simulation of an experimental site located in the Venosta Valley (South Tyrol, Italy). Here, a large set of relevant hydrological data (e.g., evapotranspiration, soil moisture) has been collected, with ground and remote sensing observations. The area of interest is part of a Long-Term Ecological Research (LTER) site, a mountain steep, heterogeneous slope, where the predominant land use types are meadow, pasture, and forest. The comparison between data and model predictions, as well as between simulations with the two IHSSMs, contributes to advance our understanding of the tradeoffs between different complexities in modeĺs process representation, model accuracy, and the ability to explain observed hydrological dynamics in alpine environments.

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.

SITE TECHNOLOGY CAPSULE: SUBSURFACE VOLATILIZATION AND VENTILATION SYSTEM (SVVS)

EPA Science Inventory

The Subsurface Volatilization and Ventilation System is an integrated technology used for attacking all phases of volatile organic compound (VOC) contamination in soil and groundwater. The SVVS technology promotes insitu remediation of soil and groundwater contaminated with or-ga...

Compositions produced using an in situ heat treatment process

DOEpatents

Roes, Augustinus Wilhelmus Maria; Nair, Vijay; Munsterman, Erwin Hunh; Van Bergen, Petrus Franciscus; Van Den Berg, Franciscus Gondulfus Antonius

2013-05-28

Methods for treating a subsurface formation and compositions produced therefrom are described herein. At least one method for producing hydrocarbons from a subsurface formation includes providing heat to the subsurface formation using an in situ heat treatment process. One or more formation particles may be formed during heating of the subsurface formation. Fluid that includes hydrocarbons and the formation particles may be produced from the subsurface formation. The formation particles in the produced fluid may include cenospheres and have an average particle size of at least 0.5 micrometers.

Compositions produced using an in situ heat treatment process

DOEpatents

Roes, Augustinus Wilhelmus Maria [Houston, TX; Nair, Vijay [Katy, TX; Munsterman, Erwin Henh [Amsterdam, NL; Van Bergen, Petrus Franciscus [Amsterdam, NL; Van Den Berg, Franciscus Gondulfus Antonius

2009-10-20

Systems, methods, and heaters for treating a subsurface formation are described herein. At least one method for producing hydrocarbons from a subsurface formation includes providing heat to the subsurface formation using an in situ heat treatment process. One or more formation particles may be formed during heating of the subsurface formation. Fluid that includes hydrocarbons and the formation particles may be produced from the subsurface formation. The formation particles in the produced fluid may include cenospheres and have an average particle size of at least 0.5 micrometers.

Long-term electrical resistivity monitoring of recharge-induced contaminant plume behavior.

PubMed

Gasperikova, Erika; Hubbard, Susan S; Watson, David B; Baker, Gregory S; Peterson, John E; Kowalsky, Michael B; Smith, Meagan; Brooks, Scott

2012-11-01

Geophysical measurements, and electrical resistivity tomography (ERT) data in particular, are sensitive to properties that are related (directly or indirectly) to hydrological processes. The challenge is in extracting information from geophysical data at a relevant scale that can be used to gain insight about subsurface behavior and to parameterize or validate flow and transport models. Here, we consider the use of ERT data for examining the impact of recharge on subsurface contamination at the S-3 ponds of the Oak Ridge Integrated Field Research Challenge (IFRC) site in Tennessee. A large dataset of time-lapse cross-well and surface ERT data, collected at the site over a period of 12 months, is used to study time variations in resistivity due to changes in total dissolved solids (primarily nitrate). The electrical resistivity distributions recovered from cross-well and surface ERT data agrees well, and both of these datasets can be used to interpret spatiotemporal variations in subsurface nitrate concentrations due to rainfall, although the sensitivity of the electrical resistivity response to dilution varies with nitrate concentration. Using the time-lapse surface ERT data interpreted in terms of nitrate concentrations, we find that the subsurface nitrate concentration at this site varies as a function of spatial position, episodic heavy rainstorms (versus seasonal and annual fluctuations), and antecedent rainfall history. These results suggest that the surface ERT monitoring approach is potentially useful for examining subsurface plume responses to recharge over field-relevant scales. Published by Elsevier B.V.

Subsurface damage in precision ground ULE(R) and Zerodur(R) surfaces.

PubMed

Tonnellier, X; Morantz, P; Shore, P; Baldwin, A; Evans, R; Walker, D D

2007-09-17

The total process cycle time for large ULE((R)) and Zerodur((R))optics can be improved using a precise and rapid grinding process, with low levels of surface waviness and subsurface damage. In this paper, the amounts of defects beneath ULE((R)) and Zerodur((R) )surfaces ground using a selected grinding mode were compared. The grinding response was characterised by measuring: surface roughness, surface profile and subsurface damage. The observed subsurface damage can be separated into two distinct depth zones, which are: 'process' and 'machine dynamics' related.

Integrated water flow model and modflow-farm process: A comparison of theory, approaches, and features of two integrated hydrologic models

USGS Publications Warehouse

Dogrul, Emin C.; Schmid, Wolfgang; Hanson, Randall T.; Kadir, Tariq; Chung, Francis

2016-01-01

Effective modeling of conjunctive use of surface and subsurface water resources requires simulation of land use-based root zone and surface flow processes as well as groundwater flows, streamflows, and their interactions. Recently, two computer models developed for this purpose, the Integrated Water Flow Model (IWFM) from the California Department of Water Resources and the MODFLOW with Farm Process (MF-FMP) from the US Geological Survey, have been applied to complex basins such as the Central Valley of California. As both IWFM and MFFMP are publicly available for download and can be applied to other basins, there is a need to objectively compare the main approaches and features used in both models. This paper compares the concepts, as well as the method and simulation features of each hydrologic model pertaining to groundwater, surface water, and landscape processes. The comparison is focused on the integrated simulation of water demand and supply, water use, and the flow between coupled hydrologic processes. The differences in the capabilities and features of these two models could affect the outcome and types of water resource problems that can be simulated.

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

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

Keating, Kristina; Slater, Lee; Ntarlagiannis, Dimitris

2015-02-24

This documents contains the final report for the project "Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods" (DE-SC0007049) Executive Summary: Our research aimed to develop borehole measurement techniques capable of monitoring subsurface processes, such as changes in pore geometry and iron/sulfur geochemistry, associated with remediation of heavy metals and radionuclides. Previous work has demonstrated that geophysical method spectral induced polarization (SIP) can be used to assess subsurface contaminant remediation; however, SIP signals can be generated from multiple sources limiting their interpretation value. Integrating multiple geophysical methods, such as nuclear magnetic resonance (NMR)more » and magnetic susceptibility (MS), with SIP, could reduce the ambiguity of interpretation that might result from a single method. Our research efforts entails combining measurements from these methods, each sensitive to different mineral forms and/or mineral-fluid interfaces, providing better constraints on changes in subsurface biogeochemical processes and pore geometries significantly improving our understanding of processes impacting contaminant remediation. The Rifle Integrated Field Research Challenge (IFRC) site was used as a test location for our measurements. The Rifle IFRC site is located at a former uranium ore-processing facility in Rifle, Colorado. Leachate from spent mill tailings has resulted in residual uranium contamination of both groundwater and sediments within the local aquifer. Studies at the site include an ongoing acetate amendment strategy, native microbial populations are stimulated by introduction of carbon intended to alter redox conditions and immobilize uranium. To test the geophysical methods in the field, NMR and MS logging measurements were collected before, during, and after acetate amendment. Next, laboratory NMR, MS, and SIP measurements were collected on columns of Rifle sediments during acetate amendment. The laboratory experiments were designed to simulate the field experiments; changes in geophysical signals were expected to correlate with changes in redox conditions and iron speciation. Field MS logging measurements revealed vertically stratified magnetic mineralization, likely the result of detrital magnetic fraction within the bulk alluvium. Little to no change was observed in the MS data suggesting negligible production of magnetic phases (e.g. magnetite, pyrrhotite) as a result of sulfidogenesis. Borehole NMR measurements contained high levels of noise contamination requiring significant signal processing, and analysis suggests that any changes may be difficult to differentiate from simultaneous changes in water content. Laboratory MS and NMR measurements remained relatively stable throughout the course of the acetate amendment experiment, consistent with field measurements. However, SIP measurements changed during the acetate amendment associated with the formation of iron-sulfide mineral phases; a finding that is consistent with chemical analysis of the solid phase materials in the columns.« less

Geophysical characterisation of the groundwater-surface water interface

NASA Astrophysics Data System (ADS)

McLachlan, P. J.; Chambers, J. E.; Uhlemann, S. S.; Binley, A.

2017-11-01

Interactions between groundwater (GW) and surface water (SW) have important implications for water quantity, water quality, and ecological health. The subsurface region proximal to SW bodies, the GW-SW interface, is crucial as it actively regulates the transfer of nutrients, contaminants, and water between GW systems and SW environments. However, geological, hydrological, and biogeochemical heterogeneity in the GW-SW interface makes it difficult to characterise with direct observations. Over the past two decades geophysics has been increasingly used to characterise spatial and temporal variability throughout the GW-SW interface. Geophysics is a powerful tool in evaluating structural heterogeneity, revealing zones of GW discharge, and monitoring hydrological processes. Geophysics should be used alongside traditional hydrological and biogeochemical methods to provide additional information about the subsurface. Further integration of commonly used geophysical techniques, and adoption of emerging techniques, has the potential to improve understanding of the properties and processes of the GW-SW interface, and ultimately the implications for water quality and environmental health.

Retrieval of Ocean Subsurface Particulate Backscattering Coefficient from Space-Borne CALIOP Lidar Measurement

NASA Technical Reports Server (NTRS)

Lu, Xiaomei; Hu, Yongxiang; Pelon, Jacques; Trepte, Chip; Liu, Katie; Rodier, Sharon; Zeng, Shan; Luckher, Patricia; Verhappen, Ron; Wilson, Jamie;

In situ process monitoring in selective laser sintering using optical coherence tomography

NASA Astrophysics Data System (ADS)

Gardner, Michael R.; Lewis, Adam; Park, Jongwan; McElroy, Austin B.; Estrada, Arnold D.; Fish, Scott; Beaman, Joseph J.; Milner, Thomas E.

2018-04-01

Selective laser sintering (SLS) is an efficient process in additive manufacturing that enables rapid part production from computer-based designs. However, SLS is limited by its notable lack of in situ process monitoring when compared with other manufacturing processes. We report the incorporation of optical coherence tomography (OCT) into an SLS system in detail and demonstrate access to surface and subsurface features. Video frame rate cross-sectional imaging reveals areas of sintering uniformity and areas of excessive heat error with high temporal resolution. We propose a set of image processing techniques for SLS process monitoring with OCT and report the limitations and obstacles for further OCT integration with SLS systems.

A High Resolution, Integrated Approach to Modeling Climate Change Impacts to a Mountain Headwaters Catchment using ParFlow

NASA Astrophysics Data System (ADS)

Pribulick, C. E.; Maxwell, R. M.; Williams, K. H.; Carroll, R. W. H.

2014-12-01

Prediction of environmental response to global climate change is paramount for regions that rely upon snowpack for their dominant water supply. Temperature increases are anticipated to be greater at higher elevations perturbing hydrologic systems that provide water to millions of downstream users. In this study, the relationships between large-scale climatic change and the corresponding small-scale hydrologic processes of mountainous terrain are investigated in the East River headwaters catchment near Gothic, CO. This catchment is emblematic of many others within the upper Colorado River Basin and covers an area of 250 square kilometers, has a topographic relief of 1420 meters, an average elevation of 3266 meters and has varying stream characteristics. This site allows for the examination of the varying effect of climate-induced changes on the hydrologic response of three different characteristic components of the catchment: a steep high-energy mountain system, a medium-grade lower-energy system and a low-grade low-energy meandering floodplain. To capture the surface and subsurface heterogeneity of this headwaters system the basin has been modeled at a 10-meter resolution using ParFlow, a parallel, integrated hydrologic model. Driven by meteorological forcing, ParFlow is able to capture land surface processes and represents surface and subsurface interactions through saturated and variably saturated heterogeneous flow. Data from Digital Elevation Models (DEMs), land cover, permeability, geologic and soil maps, and on-site meteorological stations, were prepared, analyzed and input into ParFlow as layers with a grid size comprised of 1403 by 1685 cells to best represent the small-scale, high resolution model domain. Water table depth, soil moisture, soil temperature, snowpack, runoff and local energy budget values provide useful insight into the catchments response to the Intergovernmental Panel on Climate Change (IPCC) temperature projections. In the near term, coupling this watershed model with one describing a diverse suite of subsurface elemental cycling pathways, including carbon and nitrogen, will provide an improved understanding of the response of the subsurface ecosystems to hydrologic transitions induced as a result of global climate change.

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.

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.

Increasing the production efficiency and reducing the environmental impacts of hydraulic fracturing

NASA Astrophysics Data System (ADS)

Viswanathan, H. S.

2016-12-01

Shale gas is an unconventional fossil energy resource profoundly impacting US energy independence and is projected to last for at least 100 years. Production of methane and other hydrocarbons from low permeability shale involves hydraulic fracturing of rock, establishing fracture connectivity, and multiphase fluid-flow and reaction processes all of which are poorly understood. The result is inefficient extraction with many environmental concerns. A science-based capability is required to quantify the governing mesoscale fluid-solid interactions, including microstructural control of fracture patterns and the interaction of engineered fluids with hydrocarbon flow. These interactions depend on coupled thermo-hydro-mechanical-chemical (THMC) processes over scales from microns to tens of meters. Determining the key mechanisms in subsurface THMC 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 prototyped the microfluidic and triaxial core flood experiments required to reveal the fundamental dynamics of fracture-fluid interactions. The goal is transformation of hydraulic fracturing from present ad hoc approaches to science-based strategies while safely enhancing production. Specifically, we have demonstrated an integrated experimental/modeling approach that allows for a comprehensive characterization of fluid-solid interactions and develop models that can be used to determine the reservoir operating conditions necessary to gain a degree of control over fracture generation, fluid flow, and interfacial processes over a range of subsurface conditions.

Integrated surface and groundwater modelling in the Thames Basin, UK using the Open Modelling Interface

NASA Astrophysics Data System (ADS)

Mackay, Jonathan; Abesser, Corinna; Hughes, Andrew; Jackson, Chris; Kingdon, Andrew; Mansour, Majdi; Pachocka, Magdalena; Wang, Lei; Williams, Ann

2013-04-01

The River Thames catchment is situated in the south-east of England. It covers approximately 16,000 km2 and is the most heavily populated river basin in the UK. It is also one of the driest and has experienced severe drought events in the recent past. With the onset of climate change and human exploitation of our environment, there are now serious concerns over the sustainability of water resources in this basin with 6 million m3 consumed every day for public water supply alone. Groundwater in the Thames basin is extremely important, providing 40% of water for public supply. The principal aquifer is the Chalk, a dual permeability limestone, which has been extensively studied to understand its hydraulic properties. The fractured Jurassic limestone in the upper catchment also forms an important aquifer, supporting baseflow downstream during periods of drought. These aquifers are unconnected other than through the River Thames and its tributaries, which provide two-thirds of London's drinking water. Therefore, to manage these water resources sustainably and to make robust projections into the future, surface and groundwater processes must be considered in combination. This necessitates the simulation of the feedbacks and complex interactions between different parts of the water cycle, and the development of integrated environmental models. The Open Modelling Interface (OpenMI) standard provides a method through which environmental models of varying complexity and structure can be linked, allowing them to run simultaneously and exchange data at each timestep. This architecture has allowed us to represent the surface and subsurface flow processes within the Thames basin at an appropriate level of complexity based on our understanding of particular hydrological processes and features. We have developed a hydrological model in OpenMI which integrates a process-driven, gridded finite difference groundwater model of the Chalk with a more simplistic, semi-distributed conceptual model of the Jurassic limestone. A distributed river routing model of the Thames has also been integrated to connect the surface and subsurface hydrological processes. This application demonstrates the potential benefits and issues associated with implementing this approach.

AMISS - Active and passive MIcrowaves for Security and Subsurface imaging

NASA Astrophysics Data System (ADS)

Soldovieri, Francesco; Slob, Evert; Turk, Ahmet Serdar; Crocco, Lorenzo; Catapano, Ilaria; Di Matteo, Francesca

2013-04-01

The FP7-IRSES project AMISS - Active and passive MIcrowaves for Security and Subsurface imaging is based on a well-combined network among research institutions of EU, Associate and Third Countries (National Research Council of Italy - Italy, Technische Universiteit Delft - The Netherlands, Yildiz Technical University - Turkey, Bauman Moscow State Technical University - Russia, Usikov Institute for Radio-physics and Electronics and State Research Centre of Superconductive Radioelectronics "Iceberg" - Ukraine and University of Sao Paulo - Brazil) with the aims of achieving scientific advances in the framework of microwave and millimeter imaging systems and techniques for security and safety social issues. In particular, the involved partners are leaders in the scientific areas of passive and active imaging and are sharing their complementary knowledge to address two main research lines. The first one regards the design, characterization and performance evaluation of new passive and active microwave devices, sensors and measurement set-ups able to mitigate clutter and increase information content. The second line faces the requirements to make State-of-the-Art processing tools compliant with the instrumentations developed in the first line, suitable to work in electromagnetically complex scenarios and able to exploit the unexplored possibilities offered by new instrumentations. The main goals of the project are: 1) Development/improvement and characterization of new sensors and systems for active and passive microwave imaging; 2) Set up, analysis and validation of state of art/novel data processing approach for GPR in critical infrastructure and subsurface imaging; 3) Integration of state of art and novel imaging hardware and characterization approaches to tackle realistic situations in security, safety and subsurface prospecting applications; 4) Development and feasibility study of bio-radar technology (system and data processing) for vital signs detection and detection/characterization of human beings in complex scenarios. These goals are planned to be reached following a plan of research activities and researchers secondments which cover a period of three years. ACKNOWLEDGMENTS This research has been performed in the framework of the "Active and Passive Microwaves for Security and Subsurface imaging (AMISS)" EU 7th Framework Marie Curie Actions IRSES project (PIRSES-GA-2010-269157).

Subsurface Hydrologic Processes Revealed by Time-lapse GPR in Two Contrasting Soils in the Shale Hills CZO

NASA Astrophysics Data System (ADS)

Guo, L.; Lin, H.; Nyquist, J.; Toran, L.; Mount, G.

2017-12-01

Linking subsurface structures to their functions in determining hydrologic processes, such as soil moisture dynamics, subsurface flow patterns, and discharge behaviours, is a key to understanding and modelling hydrological systems. Geophysical techniques provide a non-invasive approach to investigate this form-function dualism of subsurface hydrology at the field scale, because they are effective in visualizing subsurface structure and monitoring the distribution of water. In this study, we used time-lapse ground-penetrating radar (GPR) to compare the hydrologic responses of two contrasting soils in the Shale Hills Critical Zone Observatory. By integrating time-lapse GPR with artificial water injection, we observed distinct flow patterns in the two soils: 1) in the deep Rushtown soil (over 1.5 m depth to bedrock) located in a concave hillslope, a lateral preferential flow network extending as far as 2 m downslope was identified above a less permeable layer and via a series of connected macropores; whereas 2) in the shallow Weikert soil ( 0.3 m depth to saprock) located in a planar hillslope, vertical infiltration into the permeable fractured shale dominated the flow field, while the development of lateral preferential flow along the hillslope was restrained. At the Weikert soil site, the addition of brilliant blue dye to the water injection followed by in situ excavation supported GPR interpretation that only limited lateral preferential flow formed along the soil-saprock interface. Moreover, seasonally repeated GPR surveys indicated different patterns of profile moisture distribution in the two soils that in comparison with the dry season, a dense layer within the BC horizon in the deep Rushtown soil prevented vertical infiltration in the wet season, leading to the accumulation of soil moisture above this layer; whereas, in the shallow Weikert soil, water infiltrated into saprock in wet seasons, building up water storage within the fractured bedrock (i.e., the rock moisture). Results of this study demonstrated the strong interplay between soil structures and subsurface hydrologic behaviors, and time-lapse GPR is an effective method to establish such a relationship under the field conditions.

Modeling the Hydrologic Response to Changes in Groundcover Conditions Caused by Fire Disturbances

NASA Astrophysics Data System (ADS)

Kikinzon, E.; Atchley, A. L.; Coon, E.; Middleton, R. S.

2016-12-01

Climate change and fire suppression increase wildfire activity, which alters ecosystem functions and can significantly impact hydrological response. Both wildfire and prescribed burns reduce groundcover, affect top layers of subsurface, and change the structure of overland flow pathways. To understand respective effects on surface and subsurface hydrology, it is imperative to accurately represent surface-subsurface interface pre and post-fire, and to model physical processes in groundcover components. We show mechanistic models used to describe physics in two key types of groundcover, litter and duff, in Advanced Terrestrial Simulator (ATS). Litter is considered to be a part of vegetative canopy covering the surface. It has associated water storage capacity, which allows simulating interception and drainage, and its thickness is used to evaluate surface roughness with potential effect of slowing overland flow compared to bare soil. Duff on the other hand is incorporated into the subsurface, thus requiring meshing and discretization capability to support complex geometries including pinchouts, which is necessary both for achieving desired mesh resolution and portraying bare soil patches without adversely affecting the time scale. As part of the subsurface, duff has its own hydrologic and water retention properties used to resolve infiltration and saturation limited runoff generation, run on, and infiltration processes. This enables the use of ATS for fine scale modeling of integrated hydrology with adequate representation of groundcover influence. To isolate the impact of changing groundcover, we consider a simple hill slope and study the hydrological response to varying amount and geometries of groundcover. To cover landscape characteristics produced by a wide variety of fire conditions, from high intensity to low intensity fire impacts, we simulate hydrologic response to precipitation events over a number of typical geometries and with fine control over amounts of two described types of groundcover. We then analyze hydrological sensitivity to presence or absence of particular groundcover types, their respective patchiness, and possible changes in overland flow pathways.

Subsurface flow pathway dynamics in the active layer of coupled permafrost-hydrogeological systems under seasonal and annual temperature variability.

NASA Astrophysics Data System (ADS)

Frampton, Andrew

2017-04-01

There is a need for improved understanding of the mechanisms controlling subsurface solute transport in the active layer in order to better understand permafrost-hydrological-carbon feedbacks, in particular with regards to how dissolved carbon is transported in coupled surface and subsurface terrestrial arctic water systems under climate change. Studying solute transport in arctic systems is also relevant in the context of anthropogenic pollution which may increase due to increased activity in cold region environments. In this contribution subsurface solute transport subject to ground surface warming causing permafrost thaw and active layer change is studied using a physically based model of coupled cryotic and hydrogeological flow processes combined with a particle tracking method. Changes in subsurface water flows and solute transport travel times are analysed for different modelled geological configurations during a 100-year warming period. Results show that for all simulated cases, the minimum and mean travel times increase non-linearly with warming irrespective of geological configuration and heterogeneity structure. The timing of the start of increase in travel time depends on heterogeneity structure, combined with the rate of permafrost degradation that also depends on material thermal and hydrogeological properties. These travel time changes are shown to depend on combined warming effects of increase in pathway length due to deepening of the active layer, reduced transport velocities due to a shift from horizontal saturated groundwater flow near the surface to vertical water percolation deeper into the subsurface, and pathway length increase and temporary immobilization caused by cryosuction-induced seasonal freeze cycles. The impact these change mechanisms have on solute and dissolved substance transport is further analysed by integrating pathway analysis with a Lagrangian approach, incorporating considerations for both dissolved organic and inorganic carbon releases. Further model development challenges are also highlighted and discussed, including coupling between subsurface and surface runoff, soil deformations, as well as site applications and larger system scales.

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

Hammond, Glenn Edward; Bao, J; Huang, M

Hyporheic exchange is a critical mechanism shaping hydrological and biogeochemical processes along a river corridor. Recent studies on quantifying the hyporheic exchange were mostly limited to local scales due to field inaccessibility, computational demand, and complexity of geomorphology and subsurface geology. Surface flow conditions and subsurface physical properties are well known factors on modulating the hyporheic exchange, but quantitative understanding of their impacts on the strength and direction of hyporheic exchanges at reach scales is absent. In this study, a high resolution computational fluid dynamics (CFD) model that couples surface and subsurface flow and transport is employed to simulate hyporheicmore » exchanges in a 7-km long reach along the main-stem of the Columbia River. Assuming that the hyporheic exchange does not affect surface water flow conditions due to its negligible magnitude compared to the volume and velocity of river water, we developed a one-way coupled surface and subsurface water flow model using the commercial CFD software STAR-CCM+. The model integrates the Reynolds-averaged Navier-Stokes (RANS) equation solver with a realizable κ-ε two-layer turbulence model, a two-layer all y + wall treatment, and the volume of fluid (VOF) method, and is used to simulate hyporheic exchanges by tracking the free water-air interface as well as flow in the river and the subsurface porous media. The model is validated against measurements from acoustic Doppler current profiler (ADCP) in the stream water and hyporheic fluxes derived from a set of temperature profilers installed across the riverbed. The validated model is then employed to systematically investigate how hyporheic exchanges are influenced by surface water fluid dynamics strongly regulated by upstream dam operations, as well as subsurface structures (e.g. thickness of riverbed and subsurface formation layers) and hydrogeological properties (e.g. permeability). The results suggest that the thickness of riverbed alluvium layer is the dominant factor for reach-scale hyporheic exchanges, followed by the alluvium permeability, the depth of the underlying impermeable layer, and the assumption of hydrostatic pressure.« less

Surface/subsurface observation and removal mechanisms of ground reaction bonded silicon carbide

NASA Astrophysics Data System (ADS)

Yao, Wang; Zhang, Yu-Min; Han, Jie-cai; Zhang, Yun-long; Zhang, Jian-han; Zhou, Yu-feng; Han, Yuan-yuan

2006-01-01

Reaction Bonded Silicon Carbide (RBSiC) has long been recognized as a promising material for optical applications because of its unique combination of favorable properties and low-cost fabrication. Grinding of silicon carbide is difficult because of its high hardness and brittleness. Grinding often induces surface and subsurface damage, residual stress and other types of damage, which have great influence on the ceramic components for optical application. In this paper, surface integrity, subsurface damage and material removal mechanisms of RBSiC ground using diamond grinding wheel on creep-feed surface grinding machine are investigated. The surface and subsurface are studied with scanning electron microscopy (SEM) and optical microscopy. The effects of grinding conditions on surface and subsurface damage are discussed. This research links the surface roughness, surface and subsurface cracks to grinding parameters and provides valuable insights into the material removal mechanism and the dependence of grind induced damage on grinding conditions.

Study of the effect of wind speed on evaporation from soil through integrated modeling of the atmospheric boundary layer and shallow subsurface.

PubMed

Davarzani, Hossein; Smits, Kathleen; Tolene, Ryan M; Illangasekare, Tissa

2014-01-01

In an effort to develop methods based on integrating the subsurface to the atmospheric boundary layer to estimate evaporation, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model was tested using experimental data to study the effect of wind speed on evaporation. The model consists of the coupled equations of mass conservation for two-phase flow in porous medium with single-phase flow in the free-flow domain under nonisothermal, nonequilibrium phase change conditions. In this model, the evaporation rate and soil surface temperature and relative humidity at the interface come directly from the integrated model output. To experimentally validate numerical results, we developed a unique test system consisting of a wind tunnel interfaced with a soil tank instrumented with a network of sensors to measure soil-water variables. Results demonstrated that, by using this coupling approach, it is possible to predict the different stages of the drying process with good accuracy. Increasing the wind speed increases the first stage evaporation rate and decreases the transition time between two evaporative stages (soil water flow to vapor diffusion controlled) at low velocity values; then, at high wind speeds the evaporation rate becomes less dependent on the wind speed. On the contrary, the impact of wind speed on second stage evaporation (diffusion-dominant stage) is not significant. We found that the thermal and solute dispersion in free-flow systems has a significant influence on drying processes from porous media and should be taken into account.

Study of the effect of wind speed on evaporation from soil through integrated modeling of the atmospheric boundary layer and shallow subsurface

PubMed Central

Davarzani, Hossein; Smits, Kathleen; Tolene, Ryan M; Illangasekare, Tissa

2014-01-01

In an effort to develop methods based on integrating the subsurface to the atmospheric boundary layer to estimate evaporation, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model was tested using experimental data to study the effect of wind speed on evaporation. The model consists of the coupled equations of mass conservation for two-phase flow in porous medium with single-phase flow in the free-flow domain under nonisothermal, nonequilibrium phase change conditions. In this model, the evaporation rate and soil surface temperature and relative humidity at the interface come directly from the integrated model output. To experimentally validate numerical results, we developed a unique test system consisting of a wind tunnel interfaced with a soil tank instrumented with a network of sensors to measure soil-water variables. Results demonstrated that, by using this coupling approach, it is possible to predict the different stages of the drying process with good accuracy. Increasing the wind speed increases the first stage evaporation rate and decreases the transition time between two evaporative stages (soil water flow to vapor diffusion controlled) at low velocity values; then, at high wind speeds the evaporation rate becomes less dependent on the wind speed. On the contrary, the impact of wind speed on second stage evaporation (diffusion-dominant stage) is not significant. We found that the thermal and solute dispersion in free-flow systems has a significant influence on drying processes from porous media and should be taken into account. PMID:25309005

A geological model for the management of subsurface data in the urban environment of Barcelona and surrounding area

NASA Astrophysics Data System (ADS)

Vázquez-Suñé, Enric; Ángel Marazuela, Miguel; Velasco, Violeta; Diviu, Marc; Pérez-Estaún, Andrés; Álvarez-Marrón, Joaquina

2016-09-01

The overdevelopment of cities since the industrial revolution has shown the need to incorporate a sound geological knowledge in the management of required subsurface infrastructures and in the assessment of increasingly needed groundwater resources. Additionally, the scarcity of outcrops and the technical difficulty to conduct underground exploration in urban areas highlights the importance of implementing efficient management plans that deal with the legacy of heterogeneous subsurface information. To deal with these difficulties, a methodology has been proposed to integrate all the available spatio-temporal data into a comprehensive spatial database and a set of tools that facilitates the analysis and processing of the existing and newly added data for the city of Barcelona (NE Spain). Here we present the resulting actual subsurface 3-D geological model that incorporates and articulates all the information stored in the database. The methodology applied to Barcelona benefited from a good collaboration between administrative bodies and researchers that enabled the realization of a comprehensive geological database despite logistic difficulties. Currently, the public administration and also private sectors both benefit from the geological understanding acquired in the city of Barcelona, for example, when preparing the hydrogeological models used in groundwater assessment plans. The methodology further facilitates the continuous incorporation of new data in the implementation and sustainable management of urban groundwater, and also contributes to significantly reducing the costs of new infrastructures.

First-order exchange coefficient coupling for simulating surface water-groundwater interactions: Parameter sensitivity and consistency with a physics-based approach

USGS Publications Warehouse

Ebel, B.A.; Mirus, B.B.; Heppner, C.S.; VanderKwaak, J.E.; Loague, K.

2009-01-01

Distributed hydrologic models capable of simulating fully-coupled surface water and groundwater flow are increasingly used to examine problems in the hydrologic sciences. Several techniques are currently available to couple the surface and subsurface; the two most frequently employed approaches are first-order exchange coefficients (a.k.a., the surface conductance method) and enforced continuity of pressure and flux at the surface-subsurface boundary condition. The effort reported here examines the parameter sensitivity of simulated hydrologic response for the first-order exchange coefficients at a well-characterized field site using the fully coupled Integrated Hydrology Model (InHM). This investigation demonstrates that the first-order exchange coefficients can be selected such that the simulated hydrologic response is insensitive to the parameter choice, while simulation time is considerably reduced. Alternatively, the ability to choose a first-order exchange coefficient that intentionally decouples the surface and subsurface facilitates concept-development simulations to examine real-world situations where the surface-subsurface exchange is impaired. While the parameters comprising the first-order exchange coefficient cannot be directly estimated or measured, the insensitivity of the simulated flow system to these parameters (when chosen appropriately) combined with the ability to mimic actual physical processes suggests that the first-order exchange coefficient approach can be consistent with a physics-based framework. Copyright ?? 2009 John Wiley & Sons, Ltd.

Deep subsurface microbial processes

USGS Publications Warehouse

Lovley, D.R.; Chapelle, F.H.

1995-01-01

Information on the microbiology of the deep subsurface is necessary in order to understand the factors controlling the rate and extent of the microbially catalyzed redox reactions that influence the geophysical properties of these environments. Furthermore, there is an increasing threat that deep aquifers, an important drinking water resource, may be contaminated by man's activities, and there is a need to predict the extent to which microbial activity may remediate such contamination. Metabolically active microorganisms can be recovered from a diversity of deep subsurface environments. The available evidence suggests that these microorganisms are responsible for catalyzing the oxidation of organic matter coupled to a variety of electron acceptors just as microorganisms do in surface sediments, but at much slower rates. The technical difficulties in aseptically sampling deep subsurface sediments and the fact that microbial processes in laboratory incubations of deep subsurface material often do not mimic in situ processes frequently necessitate that microbial activity in the deep subsurface be inferred through nonmicrobiological analyses of ground water. These approaches include measurements of dissolved H2, which can predict the predominant microbially catalyzed redox reactions in aquifers, as well as geochemical and groundwater flow modeling, which can be used to estimate the rates of microbial processes. Microorganisms recovered from the deep subsurface have the potential to affect the fate of toxic organics and inorganic contaminants in groundwater. Microbial activity also greatly influences 1 the chemistry of many pristine groundwaters and contributes to such phenomena as porosity development in carbonate aquifers, accumulation of undesirably high concentrations of dissolved iron, and production of methane and hydrogen sulfide. Although the last decade has seen a dramatic increase in interest in deep subsurface microbiology, in comparison with the study of other habitats, the study of deep subsurface microbiology is still in its infancy.

4D ground penetrating radar measurements as non-invasive means for hydrological process investigation

NASA Astrophysics Data System (ADS)

Jackisch, Conrad; Allroggen, Niklas

2017-04-01

The missing vision into the subsurface appears to be a major limiting factor for our hydrological process understanding and theory development. Today, hydrology-related sciences have collected tremendous evidence for soils acting as drainage network and retention stores simultaneously in structured and self-organising domains. However, our present observation technology relies mainly on point-scale sensors, which integrate over a volume of unknown structures and is blind for their distribution. Although heterogeneity is acknowledged at all scales, it is rarely seen as inherent system property. At small scales (soil moisture probe) and at large scales (neutron probe) our measurements leave quite some ambiguity. Consequently, spatially and temporally continuous measurement of soil water states is essential for advancing our understanding and development of subsurface process theories. We present results from several irrigation experiments accompanied by 2D and 3D time-lapse GPR for the development of a novel technique to visualise and quantify water dynamics in the subsurface. Through the comparison of TDR, tracer and gravimetric measurement of soil moisture it becomes apparent that all sensor-based techniques are capable to record temporal dynamics, but are challenged to precisely quantify the measurements and to extrapolate them in space. At the same time excavative methods are very limited in temporal and spatial resolution. The application of non-invasive 4D GPR measurements complements the existing techniques and reveals structural and temporal dynamics simultaneously. By consequently increasing the density of the GPR data recordings in time and space, we find means to process the data also in the time-dimension. This opens ways to quantitatively analyse soil water dynamics in complex settings.

Radar Imaging of Europa's Subsurface Properties and Processes: The View from Earth

NASA Astrophysics Data System (ADS)

Blankenship, D. D.; Moore, W. B.; Young, D. A.; Peters, M. E.

2007-12-01

A primary objective of future Europa studies will be to characterize the distribution of shallow subsurface water as well as to identify any ice-ocean interface. Another objective will be to understand the formation of surface and subsurface features associated with interchange processes between any ocean and the surface. Achieving these objectives will require either direct or inferred knowledge of the position of any ice/water interfaces as well as any brine or layer pockets. We will review the hypothesized processes that control the thermal, compositional and structural (TCS) properties, and therefore the dielectric character, of the subsurface of Europa's icy shell. Our approach will be to extract the TCS properties for various subsurface processes thought to control the formation of major surface (e.g., ridges/bands, lenticulae, chaos, cratering...) and subsurface (e.g., rigid shell eutectics, diapirs, accretionary lenses ...) features on Europa. We will then assess the spectrum of analog processes and TCS properties represented by Earth's cryosphere including both Arctic and Antarctic ice sheets, ice shelves and valley glaciers. There are few complete analogs over the full TCS space but, because of the wide range of ice thickness, impurities and strain rates for Earth's cryosphere, there are many more analogs than many Earth and planetary researchers might imagine for significant portions of this space (e.g., bottom crevasses, marine ice shelf/subglacial lake accretion, surging polythermal glaciers...).Our ultimate objective is to use these Earth analog studies to define the radar imaging approach for Europa's subsurface that will be most useful for supporting/refuting the hypotheses for the formation of major surface/subsurface features as well as for "pure" exploration of Europa's icy shell and its interface with the underlying ocean.

3D Geological Mapping - uncovering the subsurface to increase environmental understanding

NASA Astrophysics Data System (ADS)

Kessler, H.; Mathers, S.; Peach, D.

2012-12-01

Geological understanding is required for many disciplines studying natural processes from hydrology to landscape evolution. The subsurface structure of rocks and soils and their properties occupies three-dimensional (3D) space and geological processes operate in time. Traditionally geologists have captured their spatial and temporal knowledge in 2 dimensional maps and cross-sections and through narrative, because paper maps and later two dimensional geographical information systems (GIS) were the only tools available to them. Another major constraint on using more explicit and numerical systems to express geological knowledge is the fact that a geologist only ever observes and measures a fraction of the system they study. Only on rare occasions does the geologist have access to enough real data to generate meaningful predictions of the subsurface without the input of conceptual understanding developed from and knowledge of the geological processes responsible for the deposition, emplacement and diagenesis of the rocks. This in turn has led to geology becoming an increasingly marginalised science as other disciplines have embraced the digital world and have increasingly turned to implicit numerical modelling to understand environmental processes and interactions. Recent developments in geoscience methodology and technology have gone some way to overcoming these barriers and geologists across the world are beginning to routinely capture their knowledge and combine it with all available subsurface data (of often highly varying spatial distribution and quality) to create regional and national geological three dimensional geological maps. This is re-defining the way geologists interact with other science disciplines, as their concepts and knowledge are now expressed in an explicit form that can be used downstream to design process models structure. For example, groundwater modellers can refine their understanding of groundwater flow in three dimensions or even directly parameterize their numerical models using outputs from 3D mapping. In some cases model code is being re-designed in order to deal with the increasing geological complexity expressed by Geologists. These 3D maps contain have inherent uncertainty, just as their predecessors, 2D geological maps had, and there remains a significant body of work to quantify and effectively communicate this uncertainty. Here we present examples of regional and national 3D maps from Geological Survey Organisations worldwide and how these are being used to better solve real-life environmental problems. The future challenge for geologists is to make these 3D maps easily available in an accessible and interoperable form so that the environmental science community can truly integrate the hidden subsurface into a common understanding of the whole geosphere.

Microbiological, Geochemical and Hydrologic Processes Controlling Uranium Mobility: An Integrated Field Scale Subsurface Research Challenge Site at Rifle, Colorado, February 2011 to January 2012

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

Long, Philip E.; Banfield, Jill; Chandler, Darrell P.

The Rifle IFRC continued to make excellent progress during the last 12 months. As noted above, a key field experiment (Best Western) was performed during 2011 as a logical follow-on to the Super 8 field experiment preformed in 2010. In the Super 8 experiment, we successfully combined desorption and bioreduction and deployed a number of novel tracer techniques to enhance our ability to interpret the biogeochemistry of the experiment. In the Best Western experiment, we used the same experimental plot (Plot C) as was used for Super 8. The overarching objective of the Best Western field experiment was to comparedmore » the impacts of abiotic vs. biotic increases in alkalinity and to assess the mass of the sorbed pool of U(VI) at Rifle at the field scale. Both of these objectives were met. Preliminary analysis of the data indicate that the underlying biogeochemical data sets were obtained that will support a mechanistic understanding of the underlying processes, including remarkable insight into previously unrecognized microbial processes taking place during acetate amendment of the subsurface for a second time.« less

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.

Opportunities and challenges in studies of deep life (Invited)

NASA Astrophysics Data System (ADS)

Edwards, K. J.

2010-12-01

Over the past two decades, there has been an increasing awareness within the geological, microbiological, and oceanographic communities of the potentially vast microbial biosphere that is harbored beneath the surface of the Earth. With this awareness has come a mounting effort to study this potential biome - to better quantify biomass abundance, activity, and biogeochemical activity. In the Earth system, the largest deep subsurface biome is also the least accessible - the deep ocean subsurface biosphere. The oceanic deep biosphere also has greatest potential for influencing global scale biogeochemical processes -the carbon and energy cycles for example, and other elemental cycles. To address these topics and mount interdisciplinary efforts to study the deep subsurface marine biosphere, we have recently formed a center in support integrative, collaborative investigations. The national science foundation Center for Dark Biosphere Investigations (C-DEBI), has been initiated for the explicit purpose of resolving the extent, function, dynamics and implications of the subseafloor biosphere. This talk will discuss C-DEBI science, with focus on some of the opportunities and challenges in the study of deep life in the ocean, and the role that C-DEBI will play in meeting them

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

Archaea in Organic-Lean and Organic-Rich Marine Subsurface Sediments: An Environmental Gradient Reflected in Distinct Phylogenetic Lineages

PubMed Central

Durbin, Alan M.; Teske, Andreas

2012-01-01

Examining the patterns of archaeal diversity in little-explored organic-lean marine subsurface sediments presents an opportunity to study the association of phylogenetic affiliation and habitat preference in uncultured marine Archaea. Here we have compiled and re-analyzed published archaeal 16S rRNA clone library datasets across a spectrum of sediment trophic states characterized by a wide range of terminal electron-accepting processes. Our results show that organic-lean marine sediments in deep marine basins and oligotrophic open ocean locations are inhabited by distinct lineages of archaea that are not found in the more frequently studied, organic-rich continental margin sediments. We hypothesize that different combinations of electron donor and acceptor concentrations along the organic-rich/organic-lean spectrum result in distinct archaeal communities, and propose an integrated classification of habitat characteristics and archaeal community structure. PMID:22666218

Using Laser Ultrasound to Detect Subsurface Defects in Metal Laser Powder Bed Fusion Components

NASA Astrophysics Data System (ADS)

Everton, Sarah; Dickens, Phill; Tuck, Chris; Dutton, Ben

2018-03-01

Laser powder bed fusion offers many advantages over conventional manufacturing methods, such as the integration of multiple parts that can result in significant weight-savings. The increased design freedom that layer-wise manufacture allows has also been seen to enhance component performance at little or no added cost. For such benefits to be realized, however, the material quality must first be assured. Laser ultrasonic testing is a noncontact inspection technique that has been proposed as suitable for in situ monitoring of metal additive manufacturing processes. This article explores the current capability of this technique to detect manufactured, subsurface defects in Ti-6Al-4V samples, ex situ. The results are compared with x-ray computed tomography reconstructions and focus variation microscopy. Although laser ultrasound has been used to identify material discontinuities, further work is required before this technique could be implemented in situ.

Review of intraoperative optical coherence tomography: technology and applications [Invited

PubMed Central

Carrasco-Zevallos, Oscar M.; Viehland, Christian; Keller, Brenton; Draelos, Mark; Kuo, Anthony N.; Toth, Cynthia A.; Izatt, Joseph A.

2017-01-01

During microsurgery, en face imaging of the surgical field through the operating microscope limits the surgeon’s depth perception and visualization of instruments and sub-surface anatomy. Surgical procedures outside microsurgery, such as breast tumor resections, may also benefit from visualization of the sub-surface tissue structures. The widespread clinical adoption of optical coherence tomography (OCT) in ophthalmology and its growing prominence in other fields, such as cancer imaging, has motivated the development of intraoperative OCT for real-time tomographic visualization of surgical interventions. This article reviews key technological developments in intraoperative OCT and their applications in human surgery. We focus on handheld OCT probes, microscope-integrated OCT systems, and OCT-guided laser treatment platforms designed for intraoperative use. Moreover, we discuss intraoperative OCT adjuncts and processing techniques currently under development to optimize the surgical feedback derivable from OCT data. Lastly, we survey salient clinical studies of intraoperative OCT for human surgery. PMID:28663853

Local control on precipitation in a fully coupled climate-hydrology model.

PubMed

Larsen, Morten A D; Christensen, Jens H; Drews, Martin; Butts, Michael B; Refsgaard, Jens C

2016-03-10

The ability to simulate regional precipitation realistically by climate models is essential to understand and adapt to climate change. Due to the complexity of associated processes, particularly at unresolved temporal and spatial scales this continues to be a major challenge. As a result, climate simulations of precipitation often exhibit substantial biases that affect the reliability of future projections. Here we demonstrate how a regional climate model (RCM) coupled to a distributed hydrological catchment model that fully integrates water and energy fluxes between the subsurface, land surface, plant cover and the atmosphere, enables a realistic representation of local precipitation. Substantial improvements in simulated precipitation dynamics on seasonal and longer time scales is seen for a simulation period of six years and can be attributed to a more complete treatment of hydrological sub-surface processes including groundwater and moisture feedback. A high degree of local influence on the atmosphere suggests that coupled climate-hydrology models have a potential for improving climate projections and the results further indicate a diminished need for bias correction in climate-hydrology impact studies.

Local control on precipitation in a fully coupled climate-hydrology model

PubMed Central

Larsen, Morten A. D.; Christensen, Jens H.; Drews, Martin; Butts, Michael B.; Refsgaard, Jens C.

2016-01-01

The ability to simulate regional precipitation realistically by climate models is essential to understand and adapt to climate change. Due to the complexity of associated processes, particularly at unresolved temporal and spatial scales this continues to be a major challenge. As a result, climate simulations of precipitation often exhibit substantial biases that affect the reliability of future projections. Here we demonstrate how a regional climate model (RCM) coupled to a distributed hydrological catchment model that fully integrates water and energy fluxes between the subsurface, land surface, plant cover and the atmosphere, enables a realistic representation of local precipitation. Substantial improvements in simulated precipitation dynamics on seasonal and longer time scales is seen for a simulation period of six years and can be attributed to a more complete treatment of hydrological sub-surface processes including groundwater and moisture feedback. A high degree of local influence on the atmosphere suggests that coupled climate-hydrology models have a potential for improving climate projections and the results further indicate a diminished need for bias correction in climate-hydrology impact studies. PMID:26960564

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream-aquifer-land interactions (CP v1.0)

NASA Astrophysics Data System (ADS)

Bisht, Gautam; Huang, Maoyi; Zhou, Tian; Chen, Xingyuan; Dai, Heng; Hammond, Glenn E.; Riley, William J.; Downs, Janelle L.; Liu, Ying; Zachara, John M.

2017-12-01

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year period to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater-river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater-river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater-river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

DOE PAGES

Bisht, Gautam; Huang, Maoyi; Zhou, Tian; ...

2017-12-12

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year periodmore » to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.« less

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

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

Bisht, Gautam; Huang, Maoyi; Zhou, Tian

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year period to evaluate themore » impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.« less

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

DOE PAGES

Bisht, Gautam; Huang, Maoyi; Zhou, Tian; ...

2017-01-01

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year period to evaluate themore » impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.« less

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

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

Bisht, Gautam; Huang, Maoyi; Zhou, Tian

A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year periodmore » to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.« less

Generalized effective-mass theory of subsurface scanning tunneling microscopy: Application to cleaved quantum dots

NASA Astrophysics Data System (ADS)

Roy, M.; Maksym, P. A.; Bruls, D.; Offermans, P.; Koenraad, P. M.

2010-11-01

An effective-mass theory of subsurface scanning tunneling microscopy (STM) is developed. Subsurface structures such as quantum dots embedded into a semiconductor slab are considered. States localized around subsurface structures match on to a tail that decays into the vacuum above the surface. It is shown that the lateral variation in this tail may be found from a surface envelope function provided that the effects of the slab surfaces and the subsurface structure decouple approximately. The surface envelope function is given by a weighted integral of a bulk envelope function that satisfies boundary conditions appropriate to the slab. The weight function decays into the slab inversely with distance and this slow decay explains the subsurface sensitivity of STM. These results enable STM images to be computed simply and economically from the bulk envelope function. The method is used to compute wave-function images of cleaved quantum dots and the computed images agree very well with experiment.

The Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFC Focused on Hanford’s 300 Area Uranium Plume Quality Assurance Project Plan

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

Fix, N. J.

The purpose of the project is to conduct research at an Integrated Field-Scale Research Challenge Site in the Hanford Site 300 Area, CERCLA OU 300-FF-5 (Figure 1), to investigate multi-scale mass transfer processes associated with a subsurface uranium plume impacting both the vadose zone and groundwater. The project will investigate a series of science questions posed for research related to the effect of spatial heterogeneities, the importance of scale, coupled interactions between biogeochemical, hydrologic, and mass transfer processes, and measurements/approaches needed to characterize a mass-transfer dominated system. The research will be conducted by evaluating three (3) different hypotheses focused onmore » multi-scale mass transfer processes in the vadose zone and groundwater, their influence on field-scale U(VI) biogeochemistry and transport, and their implications to natural systems and remediation. The project also includes goals to 1) provide relevant materials and field experimental opportunities for other ERSD researchers and 2) generate a lasting, accessible, and high-quality field experimental database that can be used by the scientific community for testing and validation of new conceptual and numerical models of subsurface reactive transport.« less

Critical Zone Co-dynamics: Quantifying Interactions between Subsurface, Land Surface, and Vegetation Properties Using UAV and Geophysical Approaches

NASA Astrophysics Data System (ADS)

Dafflon, B.; Leger, E.; Peterson, J.; Falco, N.; Wainwright, H. M.; Wu, Y.; Tran, A. P.; Brodie, E.; Williams, K. H.; Versteeg, R.; Hubbard, S. S.

2017-12-01

Improving understanding and modelling of terrestrial systems requires advances in measuring and quantifying interactions among subsurface, land surface and vegetation processes over relevant spatiotemporal scales. Such advances are important to quantify natural and managed ecosystem behaviors, as well as to predict how watershed systems respond to increasingly frequent hydrological perturbations, such as droughts, floods and early snowmelt. Our study focuses on the joint use of UAV-based multi-spectral aerial imaging, ground-based geophysical tomographic monitoring (incl., electrical and electromagnetic imaging) and point-scale sensing (soil moisture sensors and soil sampling) to quantify interactions between above and below ground compartments of the East River Watershed in the Upper Colorado River Basin. We evaluate linkages between physical properties (incl. soil composition, soil electrical conductivity, soil water content), metrics extracted from digital surface and terrain elevation models (incl., slope, wetness index) and vegetation properties (incl., greenness, plant type) in a 500 x 500 m hillslope-floodplain subsystem of the watershed. Data integration and analysis is supported by numerical approaches that simulate the control of soil and geomorphic characteristic on hydrological processes. Results provide an unprecedented window into critical zone interactions, revealing significant below- and above-ground co-dynamics. Baseline geophysical datasets provide lithological structure along the hillslope, which includes a surface soil horizon, underlain by a saprolite layer and the fractured Mancos shale. Time-lapse geophysical data show very different moisture dynamics in various compartments and locations during the winter and growing season. Integration with aerial imaging reveals a significant linkage between plant growth and the subsurface wetness, soil characteristics and the topographic gradient. The obtained information about the organization and connectivity of the landscape is being transferred to larger regions using aerial imaging and will be used to constrain multi-scale, multi-physics hydro-biogeochemical simulations of the East River watershed response to hydrological perturbations.

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.

Assessing the Potential Consequences of Subsurface Bioremediation: Fe-oxide Bioreductive Processes and the Propensity for Contaminant-colloid Co-transport and Media Structural Breakdown

DTIC Science & Technology

2017-05-12

were resolved by a technical approach that included three well-integrated experimental tasks follows: Task A: Quantify the impact of time- dependent ...aggregate breakdown and colloid dispersion depending on the extent of Fe(III) reduction and altered the pore structure and chemical reactivity of the porous...have significant effect on the transport of molecular and colloidal tracers (but not on the ionic tracer Br-) and colloid generation depending on

The 300 Area Integrated Field Research Challenge Quality Assurance Project Plan

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

Fix, N. J.

Pacific Northwest National Laboratory and a group of expert collaborators are using the U.S. Department of Energy Hanford Site 300 Area uranium plume within the footprint of the 300-FF-5 groundwater operable unit as a site for an Integrated Field-Scale Subsurface Research Challenge (IFRC). The IFRC is entitled Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on the Hanford Site 300 Area Uranium Plume Project. The theme is investigation of multi-scale mass transfer processes. A series of forefront science questions on mass transfer are posed for research that relate to the effect of spatial heterogeneities; themore » importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements/approaches needed to characterize and model a mass transfer-dominated system. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by the 300 Area IFRC Project. This plan is designed to be used exclusively by project staff.« less

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

Surface integrity and corrosion performance of biomedical magnesium-calcium alloy processed by hybrid dry cutting-finish burnishing.

PubMed

Salahshoor, M; Li, C; Liu, Z Y; Fang, X Y; Guo, Y B

2018-02-01

Biodegradable magnesium-calcium (MgCa) alloy is a very attractive orthopedic biomaterial compared to permanent metallic alloys. However, the critical issue is that MgCa alloy corrodes too fast in the human organism. Compared to dry cutting, the synergistic dry cutting-finish burnishing can significantly improve corrosion performance of MgCa0.8 (wt%) alloy by producing a superior surface integrity including good surface finish, high compressive hook-shaped residual stress profile, extended strain hardening in subsurface, and little change of grain size. A FEA model was developed to understand the plastic deformation of MgCa materials during burnishing process. The measured polarization curves, surface micrographs, and element distributions of the corroded surfaces by burnishing show an increasing and uniform corrosion resistance to simulated body fluid. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hyporheic zone hydrologic science: A historical account of its emergence and a prospectus

NASA Astrophysics Data System (ADS)

Cardenas, M. Bayani

2015-05-01

The hyporheic zone, defined by shallow subsurface pathways through river beds and banks beginning and ending at the river, is an integral and unique component of fluvial systems. It hosts myriad hydrologically controlled processes that are potentially coupled in complex ways. Understanding these processes and the connections between them is critical since these processes are not only important locally but integrate to impact increasingly larger scale biogeochemical functioning of the river corridor up to the river network scale. Thus, the hyporheic zone continues to be a growing research focus for many hydrologists for more than half the history of Water Resources Research. This manuscript partly summarizes the historical development of hyporheic zone hydrologic science as gleaned from papers published in Water Resources Research, from the birth of the concept of the hyporheic zone as a hydrologic black box (sometimes referred to as transient storage zone), to its adolescent years of being torn between occasionally competing research perspectives of interrogating the hyporheic zone from a surface or subsurface view, to its mature emergence as an interdisciplinary research field that employs the wide array of state-of-the-art tools available to the modern hydrologist. The field is vibrant and moving in the right direction of addressing critical fundamental and applied questions with no clear end in sight in its growth. There are exciting opportunities for scientists that are able to tightly link the allied fields of geology, geomorphology, hydrology, geochemistry, and ecology to tackle the many open problems in hyporheic zone science.

An integrated toolbox for processing and analysis of remote sensing data of inland and coastal waters - atmospheric correction

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

Haan, J.F. de; Kokke, J.M.M.; Hoogenboom, H.J.

1997-06-01

Deriving thematic maps of water quality parameters from a remote sensing image requires a number of processing steps, such as calibration, atmospheric correction, air-water interface correction, and application of water quality algorithms. A prototype version of an integrated software environment has recently been developed that enables the user to perform and control these processing steps. Major parts of this environment are: (i) access to the MODTRAN 3 radiative transfer code, (ii) a database of water quality algorithms, and (iii) a spectral library of Dutch coastal and inland waters, containing subsurface irradiance reflectance spectra and associated water quality parameters. The atmosphericmore » correction part of this environment is discussed here. It is shown that this part can be used to accurately retrieve spectral signatures of inland water for wavelengths between 450 and 750 nm, provided in situ measurements are used to determine atmospheric model parameters. Assessment of the usefulness of the completely integrated software system in an operational environment requires a revised version that is presently being developed.« less

The State of Stress Beyond the Borehole

NASA Astrophysics Data System (ADS)

Johnson, P. A.; Coblentz, D. D.; Maceira, M.; Delorey, A. A.; Guyer, R. A.

2015-12-01

The state of stress controls all in-situ reservoir activities and yet we lack the quantitative means to measure it. This problem is important in light of the fact that the subsurface provides more than 80 percent of the energy used in the United States and serves as a reservoir for geological carbon sequestration, used fuel disposition, and nuclear waste storage. Adaptive control of subsurface fractures and fluid flow is a crosscutting challenge being addressed by the new Department of Energy SubTER Initiative that has the potential to transform subsurface energy production and waste storage strategies. Our methodology to address the above mentioned matter is based on a novel Advance Multi-Physics Tomographic (AMT) approach for determining the state of stress, thereby facilitating our ability to monitor and control subsurface geomechanical processes. We developed the AMT algorithm for deriving state-of-stress from integrated density and seismic velocity models and demonstrate the feasibility by applying the AMT approach to synthetic data sets to assess accuracy and resolution of the method as a function of the quality and type of geophysical data. With this method we can produce regional- to basin-scale maps of the background state of stress and identify regions where stresses are changing. Our approach is based on our major advances in the joint inversion of gravity and seismic data to obtain the elastic properties for the subsurface; and coupling afterwards the output from this joint-inversion with theoretical model such that strain (and subsequently) stress can be computed. Ultimately we will obtain the differential state of stress over time to identify and monitor critically stressed faults and evolving regions within the reservoir, and relate them to anthropogenic activities such as fluid/gas injection.

Geosfear? - Overcoming System Boundaries by Open-source Based Monitoring of Spatio-temporal Processes

NASA Astrophysics Data System (ADS)

Brandt, T.; Schima, R.; Goblirsch, T.; Paschen, M.; Francyk, B.; Bumberger, J.; Zacharias, S.; Dietrich, P.; Rubin, Y.; Rinke, K.; Fleckenstein, J. H.; Schmidt, C.; Vieweg, M.

2016-12-01

The impact of global change, intensive agriculture and complex interactions between humans and the environment show different effects on different scales. However, the desire to obtain a better understanding of ecosystems and process dynamics in nature accentuates the need for observing these processes at higher temporal and spatial resolutions. Especially with regard to the process dynamics and heterogeneity of rivers and catchment areas, a comprehensive monitoring of the ongoing processes and effects remains to be a challenging issue. What we need are monitoring systems which can collect most diverse data across different environmental compartments and scales. Today, open-source based electronics and innovative sensors and sensor components are offering a promising approach to investigate new possibilities of mobile data acquisition to improve our understanding of the geosphere. To start with, we have designed and implemented a multi-operable, embedded Linux platform for fast integration of different sensors within a single infrastructure. In addition, a GPS module in combination with a GSM transmitter ensures the synchronization and geo-referencing of all data, no matter how old-fashioned the sensors are. To this end, initial field experiments were conducted at a 3rd order stream in the Central German Lowland. Here, we linked in-stream DOC inputs with subsurface metabolism by coupling miniaturized DOC sensor probes with a modified vertical oxygen profiler in situ. Starting from metrological observations to water quality and subsurface conditions, the overarching goal is the detection of interlinked process dynamics across highly reactive biogeochemical interfaces. Overall, the field experiments demonstrated the feasibility of this emerging technology and its potential towards a cutting-edge strategy based on a holistic and integrated process. Now, we are only a few steps away from realizing adaptive and event-triggered observations close to real-time. Environmental monitoring and data evaluation have never been more exiting.

Controlling Subsurface Fractures and Fluid Flow: A Basic Research Agenda

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

Pyrak-Nolte, Laura J; DePaolo, Donald J.; Pietraß, Tanja

2015-05-22

From beneath the surface of the earth, we currently obtain about 80-percent of the energy our nation consumes each year. In the future we have the potential to generate billions of watts of electrical power from clean, green, geothermal energy sources. Our planet’s subsurface can also serve as a reservoir for storing energy produced from intermittent sources such as wind and solar, and it could provide safe, long-term storage of excess carbon dioxide, energy waste products and other hazardous materials. However, it is impossible to underestimate the complexities of the subsurface world. These complexities challenge our ability to acquire themore » scientific knowledge needed for the efficient and safe exploitation of its resources. To more effectively harness subsurface resources while mitigating the impacts of developing and using these resources, the U.S. Department of Energy established SubTER – the Subsurface Technology and Engineering RD&D Crosscut team. This DOE multi-office team engaged scientists and engineers from the national laboratories to assess and make recommendations for improving energy-related subsurface engineering. The SubTER team produced a plan with the overall objective of “adaptive control of subsurface fractures and fluid flow.”This plan revolved around four core technological pillars—Intelligent Wellbore Systems that sustain the integrity of the wellbore environment; Subsurface Stress and Induced Seismicity programs that guide and optimize sustainable energy strategies while reducing the risks associated with subsurface injections; Permeability Manipulation studies that improve methods of enhancing, impeding and eliminating fluid flow; and New Subsurface Signals that transform our ability to see into and characterize subsurface systems. The SubTER team developed an extensive R&D plan for advancing technologies within these four core pillars and also identified several areas where new technologies would require additional basic research. In response, the Office of Science, through its Office of Basic Energy Science (BES), convened a roundtable consisting of 15 national lab, university and industry geoscience experts to brainstorm basic research areas that underpin the SubTER goals but are currently underrepresented in the BES research portfolio. Held in Germantown, Maryland on May 22, 2015, the round-table participants developed a basic research agenda that is detailed in this report. Highlights include the following: -A grand challenge calling for advanced imaging of stress and geological processes to help understand how stresses and chemical substances are distributed in the subsurface—knowledge that is critical to all aspects of subsurface engineering; -A priority research direction aimed at achieving control of fluid flow through fractured media; -A priority research direction aimed at better understanding how mechanical and geochemical perturbations to subsurface rock systems are coupled through fluid and mineral interactions; -A priority research direction aimed at studying the structure, permeability, reactivity and other properties of nanoporous rocks, like shale, which have become critical energy materials and exhibit important hallmarks of mesoscale materials; -A cross-cutting theme that would accelerate development of advanced computational methods to describe heterogeneous time-dependent geologic systems that could, among other potential benefits, provide new and vastly improved models of hydraulic fracturing and its environmental impacts; -A cross-cutting theme that would lead to the creation of “geo-architected materials” with controlled repeatable heterogeneity and structure that can be tested under a variety of thermal, hydraulic, chemical and mechanical conditions relevant to subsurface systems; -A cross-cutting theme calling for new laboratory studies on both natural and geo-architected subsurface materials that deploy advanced high-resolution 3D imaging and chemical analysis methods to determine the ;rates and mechanisms of fluid-rock processes, and to test predictive models of such phenomena. Many of the key energy challenges of the future demand a greater understanding of the subsurface world in all of its complexity. This greater under- standing will improve the ability to control and manipulate the subsurface world in ways that will benefit both the economy and the environment. This report provides specific basic research pathways to address some of the most fundamental issues of energy-related subsurface engineering.« less

70 nm resolution in subsurface optical imaging of silicon integrated-circuits using pupil-function engineering

NASA Astrophysics Data System (ADS)

Serrels, K. A.; Ramsay, E.; Reid, D. T.

2009-02-01

We present experimental evidence for the resolution-enhancing effect of an annular pupil-plane aperture when performing nonlinear imaging in the vectorial-focusing regime through manipulation of the focal spot geometry. By acquiring two-photon optical beam-induced current images of a silicon integrated-circuit using solid-immersion-lens microscopy at 1550 nm we achieved 70 nm resolution. This result demonstrates a reduction in the minimum effective focal spot diameter of 36%. In addition, the annular-aperture-induced extension of the depth-of-focus causes an observable decrease in the depth contrast of the resulting image and we explain the origins of this using a simulation of the imaging process.

Application of a GIS-/remote sensing-based approach for predicting groundwater potential zones using a multi-criteria data mining methodology.

PubMed

Mogaji, Kehinde Anthony; Lim, Hwee San

2017-07-01

This study integrates the application of Dempster-Shafer-driven evidential belief function (DS-EBF) methodology with remote sensing and geographic information system techniques to analyze surface and subsurface data sets for the spatial prediction of groundwater potential in Perak Province, Malaysia. The study used additional data obtained from the records of the groundwater yield rate of approximately 28 bore well locations. The processed surface and subsurface data produced sets of groundwater potential conditioning factors (GPCFs) from which multiple surface hydrologic and subsurface hydrogeologic parameter thematic maps were generated. The bore well location inventories were partitioned randomly into a ratio of 70% (19 wells) for model training to 30% (9 wells) for model testing. Application results of the DS-EBF relationship model algorithms of the surface- and subsurface-based GPCF thematic maps and the bore well locations produced two groundwater potential prediction (GPP) maps based on surface hydrologic and subsurface hydrogeologic characteristics which established that more than 60% of the study area falling within the moderate-high groundwater potential zones and less than 35% falling within the low potential zones. The estimated uncertainty values within the range of 0 to 17% for the predicted potential zones were quantified using the uncertainty algorithm of the model. The validation results of the GPP maps using relative operating characteristic curve method yielded 80 and 68% success rates and 89 and 53% prediction rates for the subsurface hydrogeologic factor (SUHF)- and surface hydrologic factor (SHF)-based GPP maps, respectively. The study results revealed that the SUHF-based GPP map accurately delineated groundwater potential zones better than the SHF-based GPP map. However, significant information on the low degree of uncertainty of the predicted potential zones established the suitability of the two GPP maps for future development of groundwater resources in the area. The overall results proved the efficacy of the data mining model and the geospatial technology in groundwater potential mapping.

Advancing Knowledge on Fugitive Natural Gas from Energy Resource Development at a Controlled Release Field Observatory

NASA Astrophysics Data System (ADS)

Cahill, A. G.; Chao, J.; Forde, O.; Prystupa, E.; Mayer, K. U.; Black, T. A.; Tannant, D. D.; Crowe, S.; Hallam, S.; Mayer, B.; Lauer, R. M.; van Geloven, C.; Welch, L. A.; Salas, C.; Levson, V.; Risk, D. A.; Beckie, R. D.

2017-12-01

Fugitive gas, comprised primarily of methane, can be unintentionally released from upstream oil and gas development either at surface from leaky infrastructure or in the subsurface through failure of energy well bore integrity. For the latter, defective cement seals around energy well casings may permit buoyant flow of natural gas from the deeper subsurface towards shallow aquifers, the ground surface and potentially into the atmosphere. Concerns associated with fugitive gas release at surface and in the subsurface include contributions to greenhouse gas emissions, subsurface migration leading to accumulation in nearby infrastructure and impacts to groundwater quality. Current knowledge of the extent of fugitive gas leakage including how to best detect and monitor over time, and particularly its migration and fate in the subsurface, is incomplete. We have established an experimental field observatory for evaluating fugitive gas leakage in an area of historic and ongoing hydrocarbon resource development within the Montney Resource Play of the Western Canadian Sedimentary Basin, British Columbia, Canada. Natural gas will be intentionally released at surface and up to 25 m below surface at various rates and durations. Resulting migration patterns and impacts will be evaluated through examination of the geology, hydrogeology, hydro-geochemistry, isotope geochemistry, hydro-geophysics, vadose zone and soil gas processes, microbiology, and atmospheric conditions. The use of unmanned aerial vehicles and remote sensors for monitoring and detection of methane will also be assessed for suitability as environmental monitoring tools. Here we outline the experimental design and describe initial research conducted to develop a detailed site conceptual model of the field observatory. Subsequently, results attained from pilot surface and sub-surface controlled natural gas releases conducted in late summer 2017 will be presented as well as results of numerical modelling conducted to plan methane release experiments in 2018 and onwards. This research will create knowledge which informs strategies to detect and monitor fugitive gas fluxes at the surface and in groundwater; as well as guide associated regulatory and technical policies.

A field evaluation of subsurface and surface runoff. II. Runoff processes

USGS Publications Warehouse

Pilgrim, D.H.; Huff, D.D.; Steele, T.D.

1978-01-01

Combined use of radioisotope tracer, flow rate, specific conductance and suspended-sediment measurements on a large field plot near Stanford, California, has provided more detailed information on surface and subsurface storm runoff processes than would be possible from any single approach used in isolation. Although the plot was surficially uniform, the runoff processes were shown to be grossly nonuniform, both spatially over the plot, and laterally and vertically within the soil. The three types of processes that have been suggested as sources of storm runoff (Horton-type surface runoff, saturated overland flow, and rapid subsurface throughflow) all occurred on the plot. The nonuniformity of the processes supports the partial- and variable-source area concepts. Subsurface storm runoff occurred in a saturated layer above the subsoil horizon, and short travel times resulted from flow through macropores rather than the soil matrix. Consideration of these observations would be necessary for physically realistic modeling of the storm runoff process. ?? 1978.

Seasonal re-emergence of North Atlantic subsurface ocean temperature anomalies and Northern hemisphere climate

NASA Astrophysics Data System (ADS)

Sinha, Bablu; Blaker, Adam; Duchez, Aurelie; Grist, Jeremy; Hewitt, Helene; Hirschi, Joel; Hyder, Patrick; Josey, Simon; Maclachlan, Craig; New, Adrian

2017-04-01

A high-resolution coupled ocean atmosphere model is used to study the effects of seasonal re-emergence of North Atlantic subsurface ocean temperature anomalies on northern hemisphere winter climate. A 50-member control simulation is integrated from September 1 to 28 February and compared with a similar ensemble with perturbed ocean initial conditions. The perturbation consists of a density-compensated subsurface (deeper than 180m) temperature anomaly corresponding to the observed subsurface temperature anomaly for September 2010, which is known to have re-emerged at the ocean surface in subsequent months. The perturbation is confined to the North Atlantic Ocean between the Equator and 65 degrees North. The model has 1/4 degree horizontal resolution in the ocean and the experiment is repeated for two atmosphere horizontal resolutions ( 60km and 25km) in order to determine whether the sensitivity of the atmosphere to re-emerging temperature anomalies is dependent on resolution. The ensembles display a wide range of reemergence behaviour, in some cases re-emergence occurs by November, in others it is delayed or does not occur at all. A wide range of amplitudes of the re-emergent temperature anomalies is observed. In cases where re-emergence occurs, there is a marked effect on both the regional (North Atlantic and Europe) and hemispheric surface pressure and temperature patterns. The results highlight a potentially important process whereby ocean memory of conditions up to a year earlier can significantly enhance seasonal forecast skill.

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.

Using geothermal energy to heat a portion of a formation for an in situ heat treatment process

DOEpatents

Pieterson, Roelof; Boyles, Joseph Michael; Diebold, Peter Ulrich

2010-06-08

Methods of using geothermal energy to treat subsurface formations are described herein. Methods for using geothermal energy to treat a subsurface treatment area containing or proximate to hydrocarbons may include producing geothermally heated fluid from at least one subsurface region. Heat from at least a portion of the geothermally heated fluid may be transferred to the subsurface treatment area to heat the subsurface treatment area. At least some hydrocarbon fluids may be produced from the formation.

A Method for Partitioning Surface and Subsurface Flow Using Rainfall Simulaton and Two-Dimensional Surface Electrical Resistivity Imaging

NASA Astrophysics Data System (ADS)

Carey, A. M.; Paige, G. B.; Miller, S. N.; Carr, B. J.; Holbrook, W. S.

2014-12-01

In semi-arid rangeland environments understanding how surface and subsurface flow processes and their interactions are influenced by watershed and rainfall characteristics is critical. However, it is difficult to resolve the temporal variations between mechanisms controlling these processes and challenging to obtain field measurements that document their interactions. Better insight into how these complex systems respond hydrologically is necessary in order to refine hydrologic models and decision support tools. We are conducting field studies integrating high resolution, two-dimensional surface electrical resistivity imaging (ERI) with variable intensity rainfall simulation, to quantify real-time partitioning of rainfall into surface and subsurface response. These studies are being conducted at the hillslope scale on long-term runoff plots on four different ecological sites in the Upper Crow Creek Watershed in southeastern Wyoming. Variable intensity rainfall rates were applied using the Walnut Gulch Rainfall Simulator in which intensities were increased incrementally from 49 to 180 mm hr-1 and steady-state runoff rates for each intensity were measured. Two 13.5 m electrode arrays at 0.5 m spacing were positioned on the surface perpendicular to each plot and potentials were measured at given time intervals prior to, during and following simulations using a dipole-dipole array configuration. The configuration allows for a 2.47 m depth of investigation in which magnitude and direction of subsurface flux can be determined. We used the calculated steady state infiltration rates to quantify the variability in the partial area runoff response on the ecological sites. Coupling this information with time-lapse difference inversions of ERI data, we are able to track areas of increasing and decreasing resistivity in the subsurface related to localized areas of infiltration during and following rainfall events. We anticipate implementing this method across a variety of ecological sites in the Upper Crow Creek in order to characterize the variable hydrologic response of this complex rangeland watershed. This information is being used to refine current physically based hydrologic models and watershed assessment tools.

Development of monitoring and modelling tools as basis for sustainable thermal management concepts of urban groundwater bodies

NASA Astrophysics Data System (ADS)

Mueller, Matthias H.; Epting, Jannis; Köhler, Mandy; Händel, Falk; Huggenberger, Peter

2015-04-01

Increasing groundwater temperatures observed in many urban areas strongly interfere with the demand of thermal groundwater use. The groundwater temperatures in these urban areas are affected by numerous interacting factors: open and closed-loop geothermal systems for heating and cooling, sealed surfaces, constructions in the subsurface (infrastructure and buildings), artificial groundwater recharge, and interaction with rivers. On the one hand, these increasing groundwater temperatures will negatively affect the potential for its use in the future e.g. for cooling purposes. On the other hand, elevated subsurface temperatures can be considered as an energy source for shallow geothermal heating systems. Integrated thermal management concepts are therefore needed to coordinate the thermal use of groundwater in urban areas. These concepts should be based on knowledge of the driving processes which influence the thermal regime of the aquifer. We are currently investigating the processes influencing the groundwater temperature throughout the urban area of Basel City, Switzerland. This involves a three-dimensional numerical groundwater heat-transport model including geothermal use and interactions with the unsaturated zone such as subsurface constructions reaching into the aquifer. The cantonal groundwater monitoring system is an important part of the data base in our model, which will help to develop sustainable management strategies. However, single temperature measurements in conventional groundwater wells can be biased by vertical thermal convection. Therefore, multilevel observation wells are used in the urban areas of the city to monitor subsurface temperatures reaching from the unsaturated zone to the base of the aquifer. These multilevel wells are distributed in a pilot area in order to monitor the subsurface temperatures in the vicinity of deep buildings and to quantify the influence of the geothermal use of groundwater. Based on time series of the conventional groundwater wells, the multilevel observation wells and the different boundary conditions we characterize the groundwater temperature regimes using a regional groundwater heat-transport model. In the urban area of Basel, mean annual groundwater temperatures are significantly increasing with 0.05 K per year in the period of 1994 to 2014, which is most likely due to anthropogenic influences. Overall, mean annual groundwater temperatures of Basel are 3.0

Multisource data assimilation in a Richards equation-based integrated hydrological model: a real-world application to an experimental hillslope

NASA Astrophysics Data System (ADS)

Camporese, M.; Botto, A.

2017-12-01

Data assimilation is becoming increasingly popular in hydrological and earth system modeling, as it allows for direct integration of multisource observation data in modeling predictions and uncertainty reduction. For this reason, data assimilation has been recently the focus of much attention also for integrated surface-subsurface hydrological models, whereby multiple terrestrial compartments (e.g., snow cover, surface water, groundwater) are solved simultaneously, in an attempt to tackle environmental problems in a holistic approach. Recent examples include the joint assimilation of water table, soil moisture, and river discharge measurements in catchment models of coupled surface-subsurface flow using the ensemble Kalman filter (EnKF). Although the EnKF has been specifically developed to deal with nonlinear models, integrated hydrological models based on the Richards equation still represent a challenge, due to strong nonlinearities that may significantly affect the filter performance. Thus, more studies are needed to investigate the capabilities of EnKF to correct the system state and identify parameters in cases where the unsaturated zone dynamics are dominant. Here, the model CATHY (CATchment HYdrology) is applied to reproduce the hydrological dynamics observed in an experimental hillslope, equipped with tensiometers, water content reflectometer probes, and tipping bucket flow gages to monitor the hillslope response to a series of artificial rainfall events. We assimilate pressure head, soil moisture, and subsurface outflow with EnKF in a number of assimilation scenarios and discuss the challenges, issues, and tradeoffs arising from the assimilation of multisource data in a real-world test case, with particular focus on the capability of DA to update the subsurface parameters.

Subsurface high resolution definition of subsurface heterogeneity for understanding the biodynamics of natural field systems: Advancing the ability for scaling to field conditions. 1998 annual progress report

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

Majer, E.L.; Brockman, F.J.

1998-06-01

'This research is an integrated physical (geophysical and hydrologic) and microbial study using innovative geophysical imaging and microbial characterization methods to identify key scales of physical heterogeneities that affect the biodynamics of natural subsurface environments. Data from controlled laboratory and in-situ experiments at the INEEL Test Area North (TAN) site are being used to determine the dominant physical characteristics (lithologic, structural, and hydrologic) that can be imaged in-situ and correlated with microbial properties. The overall goal of this research is to contribute to the understanding of the interrelationships between transport properties and spatially varying physical, chemical, and microbiological heterogeneity. Themore » outcome will be an improved understanding of the relationship between physical and microbial heterogeneity, thus facilitating the design of bioremediation strategies in similar environments. This report summarizes work as of May 1998, the second year of the project. This work is an extension of basic research on natural heterogeneity first initiated within the DOE/OHER Subsurface Science Program (SSP) and is intended to be one of the building blocks of an integrated and collaborative approach with an INEEL/PNNL effort aimed at understanding the effect of physical heterogeneity on transport properties and biodynamics in natural systems. The work is closely integrated with other EMSP projects at INEEL (Rick Colwell et al.) and PNNL (Fred Brockman and Jim Fredrickson).'« less

Geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin

NASA Astrophysics Data System (ADS)

Vibhava, F.; Graham, W. D.; Maxwell, R. M.

2012-12-01

Streamflow at any given location and time is representative of surface and subsurface contributions from various sources. The ability to fully identify the factors controlling these contributions is key to successfully understanding the transport of contaminants through the system. In this study we developed a fully integrated 3D surface water-groundwater-land surface model, PARFLOW, to evaluate geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin in North Central Florida. In addition to traditional model evaluation criterion, such as comparing field observations to model simulated streamflow and groundwater elevations, we quantitatively evaluated the model's predictions of surface-groundwater interactions over space and time using a suite of binary end-member mixing models that were developed using observed specific conductivity differences among surface and groundwater sources throughout the domain. Analysis of model predictions showed that geologic heterogeneity exerts a strong control on both streamflow generation processes and land atmospheric fluxes in this watershed. In the upper basin, where the karst aquifer is overlain by a thick confining layer, approximately 92% of streamflow is "young" event flow, produced by near stream rainfall. Throughout the upper basin the confining layer produces a persistent high surficial water table which results in high evapotranspiration, low groundwater recharge and thus negligible "inter-event" streamflow. In the lower basin, where the karst aquifer is unconfined, deeper water tables result in less evapotranspiration. Thus, over 80% of the streamflow is "old" subsurface flow produced by diffuse infiltration through the epikarst throughout the lower basin, and all surface contributions to streamflow originate in the upper confined basin. Climatic variability provides a secondary control on surface-subsurface and land-atmosphere fluxes, producing significant seasonal and interannual variability in these processes. Spatial and temporal patterns of evapotranspiration, groundwater recharge and streamflow generation processes reveal potential hot spots and hot moments for surface and groundwater contamination in this basin.

Surface and subsurface cracks characteristics of single crystal SiC wafer in surface machining

NASA Astrophysics Data System (ADS)

Qiusheng, Y.; Senkai, C.; Jisheng, P.

2015-03-01

Different machining processes were used in the single crystal SiC wafer machining. SEM was used to observe the surface morphology and a cross-sectional cleavages microscopy method was used for subsurface cracks detection. Surface and subsurface cracks characteristics of single crystal SiC wafer in abrasive machining were analysed. The results show that the surface and subsurface cracks system of single crystal SiC wafer in abrasive machining including radial crack, lateral crack and the median crack. In lapping process, material removal is dominated by brittle removal. Lots of chipping pits were found on the lapping surface. With the particle size becomes smaller, the surface roughness and subsurface crack depth decreases. When the particle size was changed to 1.5µm, the surface roughness Ra was reduced to 24.0nm and the maximum subsurface crack was 1.2µm. The efficiency of grinding is higher than lapping. Plastic removal can be achieved by changing the process parameters. Material removal was mostly in brittle fracture when grinding with 325# diamond wheel. Plow scratches and chipping pits were found on the ground surface. The surface roughness Ra was 17.7nm and maximum subsurface crack depth was 5.8 µm. When grinding with 8000# diamond wheel, the material removal was in plastic flow. Plastic scratches were found on the surface. A smooth surface of roughness Ra 2.5nm without any subsurface cracks was obtained. Atomic scale removal was possible in cluster magnetorheological finishing with diamond abrasive size of 0.5 µm. A super smooth surface eventually obtained with a roughness of Ra 0.4nm without any subsurface crack.

Effect of synthetic iron colloids on the microbiological NH(4)(+) removal process during groundwater purification.

PubMed

Wolthoorn, Anke; Temminghoff, Erwin J M; van Riemsdijk, Willem H

2004-04-01

Subsurface aeration is used to oxidise Fe in situ in groundwater that is used to make drinking water potable. In a groundwater system with pH>7 subsurface aeration results in non-mobile Fe precipitate and mobile Fe colloids. Since originally the goal of subsurface aeration is to remove iron in situ, the formation of non-mobile iron precipitate, which facilitates the metal's removal, is the desired result. In addition to this intended effect, subsurface aeration may also strongly enhance the microbiological removal of ammonium (NH(4)(+)) in the purification station. Mobile iron colloids could be the link between subsurface aeration and the positive effect on the NH(4)(+) removal process. Therefore, the objective of this study was to assess whether synthetic iron colloids could improve the NH(4)(+) removal process. The effect of synthetic iron colloids on the NH(4)(+) removal process was studied using an artificial purification set-up on a laboratory scale. Columns that purified groundwater with or without added synthetic iron colloids were set up in duplicate. The results showed that the NH(4)(+) removal was significantly ( alpha = 0.05 ) increased in columns treated with the synthetic iron colloids. Cumulative after 4 months about 10% more NH(4)(+) was nitrified in the columns that was treated with the groundwater containing synthetic iron colloids. The results support the hypothesis that mobile iron colloids could be the link between subsurface aeration and the positive effect on the NH(4)(+) removal process.

Microbial Biogeography on the Legacies of Historical Events in the Arctic Subsurface Sediments

NASA Astrophysics Data System (ADS)

Han, Dukki; Nam, Seung-Il; Hur, Hor-Gil

2017-04-01

The Arctic marine environment consists of various microbial habitats. The niche preference of microbial assemblages in the Arctic Ocean has been surveyed with the modern environmental change by oceanographic traits such as sea-ice dynamics, current circulation, and sedimentation. The North Pacific inflow from the shallow and narrow Bering Strait is highly susceptible to sea-level fluctuations, and thus the water mass exchange mediated by the history of sea-ice between the North Pacific and the Chukchi Sea in the Arctic Ocean. Over geological timescale, the climate change may provide putative evidences for ecological niche for the Arctic microbial assemblages as well as geological records in response to the paleoclimate change. In the present study, the multidisciplinary approach, based on microbiology, geology, and geochemistry, was applied to survey the microbial assemblages in the Arctic subsurface sediments and help further integrate the microbial biogeography and biogeochemical patterns in the Arctic subsurface biosphere. Our results describe microbial assemblages with high-resolution paleoceanographic records in the Chukchi Sea sediment core (ARA02B/01A-GC; 5.4 mbsf) to show the processes that drive microbial biogeographic patterns in the Arctic subsurface sediments. We found microbial habitat preferences closely linked to Holocene paleoclimate records as well as geological, geochemical, and microbiological evidence for the inference of the sulphate-methane transition zone (SMTZ) in the Chukchi Sea. Especially, the vertically distributed predominant populations of Gammaproteobacteria and Marine Group II Euryarchaeota in the ARA02B/01A-GC consistent with the patterns of the known global SMTZs and Holocene sedimentary records, suggesting that in-depth microbiological profiles integrated with geological records may be indirectly useful for reconstructing Arctic paleoclimate changes. In the earliest phase of Mid Holocene in the ARA02B/01A-GC with concentrated crenarchaeol (a unique biomarker for Marine Group I Thaumarchaea), the most abundant archaeal population was Marine Group II Euryarchaeota rather than Marine Group I Thaumarchaea, suggesting that the interpretation of archaeal tetraether lipids in subsurface sediments needs careful consideration for paleoceanography. In conclusion, our findings have important implications for the availability of microbial biogeography in the sedimentary record. The present study offers a deeper understanding of the legacies of historical events during the Holocene and implies that the survey of microbial biogeography may be an appropriate tool to monitor potential effects from the climate change in the Arctic Ocean.

Subsurface Characterization To Support Evaluation Of Radionuclide Transport And Attenuation

EPA Science Inventory

Remediation of ground water contaminated with radionuclides may be achieved using attenuation-based technologies. These technologies may rely on engineered processes (e.g., bioremediation) or natural processes (e.g., monitored natural attenuation) within the subsurface. In gene...

CALIBRATION OF SUBSURFACE BATCH AND REACTIVE-TRANSPORT MODELS INVOLVING COMPLEX BIOGEOCHEMICAL PROCESSES

EPA Science Inventory

In this study, the calibration of subsurface batch and reactive-transport models involving complex biogeochemical processes was systematically evaluated. Two hypothetical nitrate biodegradation scenarios were developed and simulated in numerical experiments to evaluate the perfor...

Integrated Modeling and Experiments to Characterize Coupled Thermo-hydro-geomechanical-chemical processes in Hydraulic Fracturing

NASA Astrophysics Data System (ADS)

Viswanathan, H. S.; Carey, J. W.; Karra, S.; Porter, M. L.; Rougier, E.; Kang, Q.; Makedonska, N.; Hyman, J.; Jimenez Martinez, J.; Frash, L.; Chen, L.

2015-12-01

Hydraulic fracturing phenomena involve fluid-solid interactions embedded within coupled thermo-hydro-mechanical-chemical (THMC) processes over scales from microns to tens of meters. Feedbacks between processes result in complex dynamics that must be unraveled if one is to predict and, in the case of unconventional resources, facilitate fracture propagation, fluid flow, and interfacial transport processes. The proposed work is part of a broader class of complex systems involving coupled fluid flow and fractures that are critical to subsurface energy issues, such as shale oil, geothermal, carbon sequestration, and nuclear waste disposal. We use unique LANL microfluidic and triaxial core flood experiments integrated with state-of-the-art numerical simulation to reveal the fundamental dynamics of fracture-fluid interactions to characterize the key coupled processes that impact hydrocarbon production. We are also comparing CO2-based fracturing and aqueous fluids to enhance production, greatly reduce waste water, while simultaneously sequestering CO2. We will show pore, core and reservoir scale simulations/experiments that investigate the contolling mechanisms that control hydrocarbon production.

Effect of subsurface heterogeneity on free-product recovery from unconfined aquifers

NASA Astrophysics Data System (ADS)

Kaluarachchi, Jagath J.

1996-03-01

Free-product record system designs for light-hydrocarbon-contaminated sites were investigated to evaluate the effects of subsurface heterogeneity using a vertically integrated three-phase flow model. The input stochastic variable of the areal flow analysis was the log-intrinsic permeability and it was generated using the Turning Band method. The results of a series of hypothetical field-scale simulations showed that subsurface heterogeneity has a substantial effect on free-product recovery predictions. As the heterogeneity increased, the recoverable oil volume decreased and the residual trapped oil volume increased. As the subsurface anisotropy increased, these effects together with free- and total-oil contaminated areas were further enhanced. The use of multiple-stage water pumping was found to be insignificant compared to steady uniform pumping due to reduced recovery efficiency and increased residual oil volume. This observation was opposite to that produced under homogeneous scenarios. The effect of subsurface heterogeneity was enhanced at relatively low water pumping rates. The difference in results produced by homogeneous and heterogeneous simulations was substantial, indicating greater attention should be paid in modeling free-product recovery systems with appropriate subsurface heterogeneity.

Studies Based on Lunar Global Subsurface Radar Sounding Data Obtained by SELENE (Kaguya)

NASA Astrophysics Data System (ADS)

Kumamoto, A.; Yamaguchi, Y.; Yamaji, A.; Oshigami, S.; Ishiyama, K.; Nakamura, N.; Haruyama, J.; Miyamoto, H.; Nishibori, T.; Tsuchiya, F.; Ohtake, M.

2018-04-01

Several studies based on lunar global subsurface radar sounding data obtained by SELENE/LRS will be reviewed. From the subsurface structures of the buried regolith layers, we can discuss the evolution of tectonic and volcanic processes in the maria.

Subsurface microscopy of interconnect layers of an integrated circuit.

PubMed

Köklü, F Hakan; Unlü, M Selim

2010-01-15

We apply the NA-increasing lens technique to confocal and wide-field backside microscopy of integrated circuits. We demonstrate 325 nm (lambda(0)/4) lateral spatial resolution while imaging metal structures located inside the interconnect layer of an integrated circuit. Vectorial field calculations are presented justifying our findings.

In-situ Subsurface Soil Analyzer

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

Ulmer, Chris

The Department of Energy’s (DOE’s) Terrestrial Ecosystem Science (TES) program is seeking improved sensor systems for monitoring hydro-biogeochemical processes in complex subsurface environments. The TES program is specifically interested in acquiring chemical and structural information regarding the type and nature of the hydration and redox states of subsurface chemical species. The technology should be able to perform on-site and real-time measurements to provide information not available using current sample acquisition and preservation processes. To address the needs of the DOE and the terrestrial science community, Physical Optics Corporation (POC) worked on the development of a new In-Situ Subsurface Soil Analyzermore » (ISSA) based on magnetic resonance technologies. Benchtop testing was performed to assess the feasibility of continuous wave electron pair resonance (CW-EPR) detection of chemical species in subsurface soil systems.« less

Use of an uncertainty analysis for genome-scale models as a prediction tool for microbial growth processes in subsurface environments.

PubMed

Klier, Christine

2012-03-06

The integration of genome-scale, constraint-based models of microbial cell function into simulations of contaminant transport and fate in complex groundwater systems is a promising approach to help characterize the metabolic activities of microorganisms in natural environments. In constraint-based modeling, the specific uptake flux rates of external metabolites are usually determined by Michaelis-Menten kinetic theory. However, extensive data sets based on experimentally measured values are not always available. In this study, a genome-scale model of Pseudomonas putida was used to study the key issue of uncertainty arising from the parametrization of the influx of two growth-limiting substrates: oxygen and toluene. The results showed that simulated growth rates are highly sensitive to substrate affinity constants and that uncertainties in specific substrate uptake rates have a significant influence on the variability of simulated microbial growth. Michaelis-Menten kinetic theory does not, therefore, seem to be appropriate for descriptions of substrate uptake processes in the genome-scale model of P. putida. Microbial growth rates of P. putida in subsurface environments can only be accurately predicted if the processes of complex substrate transport and microbial uptake regulation are sufficiently understood in natural environments and if data-driven uptake flux constraints can be applied.

Subsurface profiling using integrated geophysical methods for 2D site response analysis in Bangalore city, India: a new approach

NASA Astrophysics Data System (ADS)

Chandran, Deepu; Anbazhagan, P.

2017-10-01

Recently, site response analysis has become a mandatory step for the design of important structures. Subsurface investigation is an essential step, from where the input parameters for the site response study like density, shear wave velocity (Vs), thickness and damping characteristics, etc, are obtained. Most site response studies at shallow bedrock sites are one-dimensional (1D) and are usually carried out by using Vs from multi-channel analysis of surface waves (MASW) or a standard penetration test (SPT) for N values with assumptions that soil layers are horizontal, uniform and homogeneous. These assumptions are not completely true in shallow bedrock regions as soil deposits are heterogeneous. The objective of this study is to generate the actual subsurface profiles in two-dimensions at shallow bedrock regions using integrated subsurface investigation testing. The study area selected for this work is Bangalore, India. Three survey lines were selected in Bangalore at two different locations; one at the Indian Institute of Science (IISc) Campus and the other at Whitefield. Geophysical surveys like ground penetrating radar (GPR) and 2D MASW were carried out at these survey lines. Geophysical test results are compared and validated with a conventional geotechnical SPT. At the IISc site, the soil profile is obtained from a trench excavated for a proposed pipeline used to compare the geophysical test results. Test results show that GPR is very useful to delineate subsurface layers, especially for shallow depths at both sites (IISc Campus and Whitefield). MASW survey results show variation of Vs values and layer thickness comparatively at deeper depths for both sites. They also show higher density soil strata with high Vs value obtained at the IISc Campus site, whereas at the Whitefield site weaker soil with low shear velocity is observed. Combining these two geophysical methods helped to generate representative 2D subsurface profiles. These subsurface profiles can be further used to understand the difference between 1D and 2D site response.

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

Qiusheng, Y., E-mail: qsyan@gdut.edu.cn; Senkai, C., E-mail: senkite@sina.com; Jisheng, P., E-mail: panjisheng@gdut.edu.cn

Different machining processes were used in the single crystal SiC wafer machining. SEM was used to observe the surface morphology and a cross-sectional cleavages microscopy method was used for subsurface cracks detection. Surface and subsurface cracks characteristics of single crystal SiC wafer in abrasive machining were analysed. The results show that the surface and subsurface cracks system of single crystal SiC wafer in abrasive machining including radial crack, lateral crack and the median crack. In lapping process, material removal is dominated by brittle removal. Lots of chipping pits were found on the lapping surface. With the particle size becomes smaller,more » the surface roughness and subsurface crack depth decreases. When the particle size was changed to 1.5µm, the surface roughness Ra was reduced to 24.0nm and the maximum subsurface crack was 1.2µm. The efficiency of grinding is higher than lapping. Plastic removal can be achieved by changing the process parameters. Material removal was mostly in brittle fracture when grinding with 325# diamond wheel. Plow scratches and chipping pits were found on the ground surface. The surface roughness Ra was 17.7nm and maximum subsurface crack depth was 5.8 µm. When grinding with 8000# diamond wheel, the material removal was in plastic flow. Plastic scratches were found on the surface. A smooth surface of roughness Ra 2.5nm without any subsurface cracks was obtained. Atomic scale removal was possible in cluster magnetorheological finishing with diamond abrasive size of 0.5 µm. A super smooth surface eventually obtained with a roughness of Ra 0.4nm without any subsurface crack.« less

Integrated hydrologic modeling: Effects of spatial scale, discretization and initialization

NASA Astrophysics Data System (ADS)

Seck, A.; Welty, C.; Maxwell, R. M.

2011-12-01

Groundwater discharge contributes significantly to the annual flows of Chesapeake Bay tributaries and is presumed to contribute to the observed lag time between the implementation of management actions and the environmental response in the Chesapeake Bay. To investigate groundwater fluxes and flow paths and interaction with surface flow, we have developed a fully distributed integrated hydrologic model of the Chesapeake Bay Watershed using ParFlow. Here we present a comparison of model spatial resolution and initialization methods. We have studied the effect of horizontal discretization on overland flow processes at a range of scales. Three nested model domains have been considered: the Monocacy watershed (5600 sq. km), the Potomac watershed (92000 sq. km) and the Chesapeake Bay watershed (400,000 sq. km). Models with homogeneous subsurface and topographically-derived slopes were evaluated at 500-m, 1000-m, 2000-m, and 4000-m grid resolutions. Land surface slopes were derived from resampled DEMs and corrected using stream networks. Simulation results show that the overland flow processes are reasonably well represented with a resolution up to 2000 m. We observe that the effects of horizontal resolution dissipate with larger scale models. Using a homogeneous model that includes subsurface and surface terrain characteristics, we have evaluated various initialization methods for the integrated Monocacy watershed model. This model used several options for water table depths and two rainfall forcing methods including (1) a synthetic rainfall-recession cycle corresponding to the region's average annual rainfall rate, and (2) an initial shut-off of rainfall forcing followed by a rainfall-recession cycling. Results show the dominance of groundwater generated runoff during a first phase of the simulation followed by a convergence towards more balanced runoff generation mechanisms. We observe that the influence of groundwater runoff increases in dissected relief areas characterized by high slope magnitudes. This is due to the increase in initial water table gradients in these regions. As a result, in the domain conditions for this study, an initial shut-off of rainfall forcing proved to be the more efficient initialization method. The initialized model is then coupled with a Land Surface Model (CLM). Ongoing work includes coupling a heterogeneous subsurface field with spatially variable meteorological forcing using the National Land Data Assimilation System (NLDAS) data products. Seasonal trends of groundwater levels for current and pre-development conditions of the basin will be compared.

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

PREDICTING SUBSURFACE CONTAMINANT TRANSPORT AND TRANSFORMATION: CONSIDERATIONS FOR MODEL SELECTION AND FIELD VALIDATION

EPA Science Inventory

Predicting subsurface contaminant transport and transformation requires mathematical models based on a variety of physical, chemical, and biological processes. The mathematical model is an attempt to quantitatively describe observed processes in order to permit systematic forecas...

Nitrogen Stimulates the Growth of Subsurface Basalt-associated Microorganisms at the Western Flank of the Mid-Atlantic Ridge

PubMed Central

Zhang, Xinxu; Fang, Jing; Bach, Wolfgang; Edwards, Katrina J.; Orcutt, Beth N.; Wang, Fengping

2016-01-01

Oceanic crust constitutes the largest aquifer system on Earth, and microbial activity in this environment has been inferred from various geochemical analyses. However, empirical documentation of microbial activity from subsurface basalts is still lacking, particularly in the cool (<25°C) regions of the crust, where are assumed to harbor active iron-oxidizing microbial communities. To test this hypothesis, we report the enrichment and isolation of crust-associated microorganisms from North Pond, a site of relatively young and cold basaltic basement on the western flank of the Mid-Atlantic Ridge that was sampled during Expedition 336 of the Integrated Ocean Drilling Program. Enrichment experiments with different carbon (bicarbonate, acetate, methane) and nitrogen (nitrate and ammonium) sources revealed significant cell growth (one magnitude higher cell abundance), higher intracellular DNA content, and increased Fe3+/ΣFe ratios only when nitrogen substrates were added. Furthermore, a Marinobacter strain with neutrophilic iron-oxidizing capabilities was isolated from the basalt. This work reveals that basalt-associated microorganisms at North Pond had the potential for activity and that microbial growth could be stimulated by in vitro nitrogen addition. Furthermore, iron oxidation is supported as an important process for microbial communities in subsurface basalts from young and cool ridge flank basement. PMID:27199959

Establishment of quantitative hydrological indexes for studies of hydro-biogeochemical interactions at the subsurface.

NASA Astrophysics Data System (ADS)

Alves Meira Neto, A.; Sengupta, A.; Wang, Y.; Volkmann, T.; Chorover, J.; Troch, P. A. A.

2017-12-01

Advances in the understanding of processes in the critical zone (CZ) are dependent on studies coupling the fields of hydrology, microbiology, geochemistry and soil development. At the same time, better insights are needed to integrate hydrologic information into biogeochemical analysis of subsurface environments. This study investigated potential hydrological indexes that help explaining spatiotemporal biogeochemical patterns. The miniLEO is a 2 m3, 10 degree sloping lysimeter located at Biosphere 2 - University of Arizona. The lysimeter was initially filled with pristine basaltic soil and subject to intermittent rainfall applications throughout the period of 18 months followed by its excavation, resulting in a grid-based sample collection at 324 locations. As a result, spatially distributed microbiological and geochemical patterns as well as soil physical properties were obtained. A hydrologic model was then developed in order to simulate the history of the system until the excavation. After being calibrated against sensor data to match its observed input-state-output behavior, the resulting distributed fields of flow velocities and moisture states were retrieved. These results were translated into several hydrological indexes to be used in with distributed microbiological and geochemical signatures. Our study attempts at conciliating sound hydrological modelling with an investigation of the subsurface biological signatures, thus providing a unique opportunity for understanding of fine-scale hydro-biological interactions.

Hillslope characterization: Identifying key controls on local-scale plant communities' distribution using remote sensing and subsurface data fusion.

NASA Astrophysics Data System (ADS)

Falco, N.; Wainwright, H. M.; Dafflon, B.; Leger, E.; Peterson, J.; Steltzer, H.; Wilmer, C.; Williams, K. H.; Hubbard, S. S.

2017-12-01

Mountainous watershed systems are characterized by extreme heterogeneity in hydrological and pedological properties that influence biotic activities, plant communities and their dynamics. To gain predictive understanding of how ecosystem and watershed system evolve under climate change, it is critical to capture such heterogeneity and to quantify the effect of key environmental variables such as topography, and soil properties. In this study, we exploit advanced geophysical and remote sensing techniques - coupled with machine learning - to better characterize and quantify the interactions between plant communities' distribution and subsurface properties. First, we have developed a remote sensing data fusion framework based on the random forest (RF) classification algorithm to estimate the spatial distribution of plant communities. The framework allows the integration of both plant spectral and structural information, which are derived from multispectral satellite images and airborne LiDAR data. We then use the RF method to evaluate the estimated plant community map, exploiting the subsurface properties (such as bedrock depth, soil moisture and other properties) and geomorphological parameters (such as slope, curvature) as predictors. Datasets include high-resolution geophysical data (electrical resistivity tomography) and LiDAR digital elevation maps. We demonstrate our approach on a mountain hillslope and meadow within the East River watershed in Colorado, which is considered to be a representative headwater catchment in the Upper Colorado Basin. The obtained results show the existence of co-evolution between above and below-ground processes; in particular, dominant shrub communities in wet and flat areas. We show that successful integration of remote sensing data with geophysical measurements allows identifying and quantifying the key environmental controls on plant communities' distribution, and provides insights into their potential changes in the future climate conditions.

Linking Surface and Subsurface Processes: Implications for Seismic Hazards in Southern California

NASA Astrophysics Data System (ADS)

Lin, J. C.; Moon, S.; Yong, A.; Meng, L.; Martin, A. J.; Davis, P. M.

2017-12-01

Earth's surface and subsurface processes such as bedrock weathering, soil production, and river incision can influence and be influenced by spatial variations in the mechanical strength of surface material. Mechanically weakened rocks tend to have reduced seismic velocity, which can result in larger ground-motion amplification and greater potential for earthquake-induced damages. However, the influence and extent of surface and subsurface processes on the mechanical strength of surface material and seismic site conditions in southern California remain unclear. In this study, we examine whether physics-based models of surface and subsurface processes can explain the spatial variability and non-linearity of near-surface seismic velocity in southern California. We use geophysical measurements (Yong et al., 2013; Ancheta et al., 2014), consisting of shear-wave velocity (Vs) tomography data, Vs profiles, and the time-averaged Vs in the upper 30 m of the crust (Vs30) to infer lateral and vertical variations of surface material properties. Then, we compare Vs30 values with geologic and topographic attributes such as rock type, slope, elevation, and local relief, as well as metrics for surface processes such as soil production and bedrock weathering from topographic stress, frost cracking, chemical reactions, and vegetation presence. Results from this study will improve our understanding of physical processes that control subsurface material properties and their influences on local variability in seismic site conditions.

Illuminating the Voluminous Subsurface Structures of Old Faithful Geyser, Yellowstone National Park

NASA Astrophysics Data System (ADS)

Hurwitz, Shaul; Shelly, David R.

2017-10-01

Old Faithful geyser in Yellowstone National Park has attracted scientific research for almost a century and a half. Temperature and pressure measurements and video recordings in the geyser's conduit led to proposals of many quantitative eruption models. Nevertheless, information on the processes that initiate the geyser's eruption in the subsurface remained limited. Two new studies, specifically Wu et al. (2017) and Ward and Lin (2017), take advantage of recent developments in seismic data acquisition technology and processing methods to illuminate subsurface structures. Using a dense array of three-component nodal geophones, these studies delineate subsurface structures on a scale larger than previously realized, which exert control on the spectacular eruptions of Old Faithful geyser.

Nitrogen fixation in denitrified marine waters.

PubMed

Fernandez, Camila; Farías, Laura; Ulloa, Osvaldo

2011-01-01

Nitrogen fixation is an essential process that biologically transforms atmospheric dinitrogen gas to ammonia, therefore compensating for nitrogen losses occurring via denitrification and anammox. Currently, inputs and losses of nitrogen to the ocean resulting from these processes are thought to be spatially separated: nitrogen fixation takes place primarily in open ocean environments (mainly through diazotrophic cyanobacteria), whereas nitrogen losses occur in oxygen-depleted intermediate waters and sediments (mostly via denitrifying and anammox bacteria). Here we report on rates of nitrogen fixation obtained during two oceanographic cruises in 2005 and 2007 in the eastern tropical South Pacific (ETSP), a region characterized by the presence of coastal upwelling and a major permanent oxygen minimum zone (OMZ). Our results show significant rates of nitrogen fixation in the water column; however, integrated rates from the surface down to 120 m varied by ∼30 fold between cruises (7.5±4.6 versus 190±82.3 µmol m(-2) d(-1)). Moreover, rates were measured down to 400 m depth in 2007, indicating that the contribution to the integrated rates of the subsurface oxygen-deficient layer was ∼5 times higher (574±294 µmol m(-2) d(-1)) than the oxic euphotic layer (48±68 µmol m(-2) d(-1)). Concurrent molecular measurements detected the dinitrogenase reductase gene nifH in surface and subsurface waters. Phylogenetic analysis of the nifH sequences showed the presence of a diverse diazotrophic community at the time of the highest measured nitrogen fixation rates. Our results thus demonstrate the occurrence of nitrogen fixation in nutrient-rich coastal upwelling systems and, importantly, within the underlying OMZ. They also suggest that nitrogen fixation is a widespread process that can sporadically provide a supplementary source of fixed nitrogen in these regions.

A vision-based weld quality evaluation system

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

Barnett, R.J.; Cook, G.E.; Strauss, A.M.

1996-12-31

Inspection of the appearance of weld beads is an integral part of the overall welding process. Lack of satisfactory appearance in itself may be sufficient grounds for part rejection or the lack of satisfactory appearance may be used as an indirect indicator of more substantive problems such as poor fusion or subsurface cracks. In all cases the inspection process tends to be both time and labor intensive. The present research uses a video system and appropriate image capture and processing to determine the quality of the weld based upon surface appearance. This relative quality rating was compared to similar ratingsmore » performed by human inspectors and was found to give very good correlation. The system was implemented for the Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW) processes.« less

Preliminary Studies of the Structural Characteristics of the Lubao Fault using 2D High Resolution Shallow Seismic Reflection Profile

NASA Astrophysics Data System (ADS)

Bonus, A. A. B.; Lagmay, A. M. A.; Rodolfo, K. S.

2016-12-01

The Lubao fault, located in the province of Pampanga, Philippines, is part of the Bataan Volcanic Arc Complex (BVAC). Active faults within and around the BVAC include the East Zambales and Iba faults; according to the official active faults map of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) there are no other existing active faults in the area. The Lubao Fault distinctly separates wetlands to the northeast and dry alluvial plains to the northwest of Manila Bay. Long term subsidence and high sedimentation rates were observed in the fault and over the past 1.5 thousand years, the northeastern block has dropped 3.5 meters. Along the southwest flank of Mount Natib, tectonic structures were identified using surface mapping and remote sensing. The Persistent Scattering Interferometric Synthetic Aperture Radar (PSInSAR) data results of Eco et al. in 2015 shows uplifts and subsidence in the BVAC area delineating the Lubao Fault. A 480-meter seismic reflection line was laid down perpendicular to the fault with a recording system consisting of 48 channels of Geometrics geophones spaced 10 meters apart. Acquired data were processed using the standard seismic reflection processing sequence by Yilmaz 2001. This preliminary study produced a high resolution subsurface profile of the Lubao fault in the village of San Rafael, Lubao where it is well manifested. The velocity model integrated by stratigraphic data of drilled core shows subsurface lithology. The depth converted profile reveals clear structures and dipping segments which indicates a history of movement along the Lubao fault. Discontinuity of reflectors, either offsets or breaks, are considered structures along the subsurface of the study area. Additional structural mapping and seismic lines along the projected fault are planned in the future to further detail the characteristics of the Lubao Fault. The surface observations made by other researchers coupled with the subsurface seismic profile mapping of this study hopes to clearly delineate and characterize the Lubao Fault.

Continuous monitoring of the lunar or Martian subsurface using on-board pattern recognition and neural processing of Rover geophysical data

NASA Technical Reports Server (NTRS)

Glass, Charles E.; Boyd, Richard V.; Sternberg, Ben K.

1991-01-01

The overall aim is to provide base technology for an automated vision system for on-board interpretation of geophysical data. During the first year's work, it was demonstrated that geophysical data can be treated as patterns and interpreted using single neural networks. Current research is developing an integrated vision system comprising neural networks, algorithmic preprocessing, and expert knowledge. This system is to be tested incrementally using synthetic geophysical patterns, laboratory generated geophysical patterns, and field geophysical patterns.

Subsurface drainage processes and management impacts

Treesearch

Elizabeth T. Keppeler; David Brown

1998-01-01

Storm-induced streamflow in forested upland watersheds is linked to rainfall by transient, variably saturated flow through several different flow paths. In the absence of exposed bedrock, shallow flow-restrictive layers, or compacted soil surfaces, virtually all of the infiltrated rainfall reaches the stream as subsurface flow. Subsurface runoff can occur within...

A Collaborative Extensible User Environment for Simulation and Knowledge Management

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

Freedman, Vicky L.; Lansing, Carina S.; Porter, Ellen A.

2015-06-01

In scientific simulation, scientists use measured data to create numerical models, execute simulations and analyze results from advanced simulators executing on high performance computing platforms. This process usually requires a team of scientists collaborating on data collection, model creation and analysis, and on authorship of publications and data. This paper shows that scientific teams can benefit from a user environment called Akuna that permits subsurface scientists in disparate locations to collaborate on numerical modeling and analysis projects. The Akuna user environment is built on the Velo framework that provides both a rich client environment for conducting and analyzing simulations andmore » a Web environment for data sharing and annotation. Akuna is an extensible toolset that integrates with Velo, and is designed to support any type of simulator. This is achieved through data-driven user interface generation, use of a customizable knowledge management platform, and an extensible framework for simulation execution, monitoring and analysis. This paper describes how the customized Velo content management system and the Akuna toolset are used to integrate and enhance an effective collaborative research and application environment. The extensible architecture of Akuna is also described and demonstrates its usage for creation and execution of a 3D subsurface simulation.« less

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.

Mid-infrared thermal imaging for an effective mapping of surface materials and sub-surface detachments in mural paintings: integration of thermography and thermal quasi-reflectography

NASA Astrophysics Data System (ADS)

Daffara, C.; Parisotto, S.; Mariotti, P. I.

2015-06-01

Cultural Heritage is discovering how precious is thermal analysis as a tool to improve the restoration, thanks to its ability to inspect hidden details. In this work a novel dual mode imaging approach, based on the integration of thermography and thermal quasi-reflectography (TQR) in the mid-IR is demonstrated for an effective mapping of surface materials and of sub-surface detachments in mural painting. The tool was validated through a unique application: the "Monocromo" by Leonardo da Vinci in Italy. The dual mode acquisition provided two spatially aligned dataset: the TQR image and the thermal sequence. Main steps of the workflow included: 1) TQR analysis to map surface features and 2) to estimate the emissivity; 3) projection of the TQR frame on reference orthophoto and TQR mosaicking; 4) thermography analysis to map detachments; 5) use TQR to solve spatial referencing and mosaicking for the thermal-processed frames. Referencing of thermal images in the visible is a difficult aspect of the thermography technique that the dual mode approach allows to solve in effective way. We finally obtained the TQR and the thermal maps spatially referenced to the mural painting, thus providing the restorer a valuable tool for the restoration of the detachments.

Active Marine Subsurface Bacterial Population Composition in Low Organic Carbon Environments from IODP Expedition 320

NASA Astrophysics Data System (ADS)

Shepard, A.; Reese, B. K.; Mills, H. J.; IODP Expedition 320 Shipboard Science Party

2011-12-01

The marine subsurface environment contains abundant and active microorganisms. These microbial populations are considered integral players in the marine subsurface biogeochemical system with significance in global geochemical cycles and reservoirs. However, variations in microbial community structure, activity and function associated with the wide-ranging sedimentary and geochemical environments found globally have not been fully resolved. Integrated Ocean Drilling Program Expedition 320 recovered sediments from site U1332. Two sampling depths were selected for analysis that spanned differing lithological units in the sediment core. Sediments were composed of mostly clay with zeolite minerals at 8 meters below sea floor (mbsf). At 27 mbsf, sediments were composed of alternating clayey radiolarian ooze and nannofossil ooze. The concentration of SO42- had little variability throughout the core and the concentration of Fe2+ remained close to, or below, detection limits (0.4 μM). Total organic carbon content ranged from a low of 0.03 wt% to a high of 0.07 wt% between 6 and 30 mbsf providing an opportunity to evaluate marine subsurface microbial communities under extreme electron donor limiting conditions. The metabolically active fraction of the bacterial population was isolated by the extraction and amplification of 16S ribosomal RNA. Pyrosequencing of 16S rRNA transcripts and subsequent bioinformatic analyses provided a robust data set (15,931 total classified sequences) to characterize the community at a high resolution. As observed in other subsurface environments, the overall diversity of active bacterial populations decreased with depth. The population shifted from a diverse but evenly distributed community at approximately 8 mbsf to a Firmicutes dominated population at 27 mbsf (80% of sequences). A total of 95% of the sequences at 27 mbsf were grouped into three genera: Lactobacillus (phylum Firmicutes) at 80% of the total sequences, Marinobacter (phylum Proteobacteria) at 8%, and Formosa (phylum Bacteroidetes) at 7%. These lineages support a paradigm suggesting the importance of fermentation in the subsurface. However, this study extends the predicted range for fermentation below the shallow subsurface and into organic carbon limited marine sediments. Other previously characterized subsurface active populations from environments with higher organic carbon concentrations do not show similar levels of reduced diversity or predominance of fermentative populations. This study further emphasizes the spatial variability of microbial populations in the deep subsurface and highlights the need for continued exploration.

Preliminary results of real-time in-vitro electronic speckle pattern interferometry (ESPI) measurements in otolaryngology

NASA Astrophysics Data System (ADS)

Conerty, Michelle D.; Castracane, James; Cacace, Anthony T.; Parnes, Steven M.; Gardner, Glendon M.; Miller, Mitchell B.

1995-05-01

Electronic Speckle Pattern Interferometry (ESPI) is a nondestructive optical evaluation technique that is capable of determining surface and subsurface integrity through the quantitative evaluation of static or vibratory motion. By utilizing state of the art developments in the areas of lasers, fiber optics and solid state detector technology, this technique has become applicable in medical research and diagnostics. Based on initial support from NIDCD and continued support from InterScience, Inc., we have been developing a range of instruments for improved diagnostic evaluation in otolaryngological applications based on the technique of ESPI. These compact fiber optic instruments are capable of making real time interferometric measurements of the target tissue. Ongoing development of image post- processing software is currently capable of extracting the desired quantitative results from the acquired interferometric images. The goal of the research is to develop a fully automated system in which the image processing and quantification will be performed in hardware in near real-time. Subsurface details of both the tympanic membrane and vocal cord dynamics could speed the diagnosis of otosclerosis, laryngeal tumors, and aid in the evaluation of surgical procedures.

Wave equation datuming applied to S-wave reflection seismic data

NASA Astrophysics Data System (ADS)

Tinivella, U.; Giustiniani, M.; Nicolich, R.

2018-05-01

S-wave high-resolution reflection seismic data was processed using Wave Equation Datuming technique in order to improve signal/noise ratio, attenuating coherent noise, and seismic resolution and to solve static corrections problems. The application of this algorithm allowed obtaining a good image of the shallow subsurface geological features. Wave Equation Datuming moves shots and receivers from a surface to another datum (the datum plane), removing time shifts originated by elevation variation and/or velocity changes in the shallow subsoil. This algorithm has been developed and currently applied to P wave, but it reveals the capacity to highlight S-waves images when used to resolve thin layers in high-resolution prospecting. A good S-wave image facilitates correlation with well stratigraphies, optimizing cost/benefit ratio of any drilling. The application of Wave Equation Datuming requires a reliable velocity field, so refraction tomography was adopted. The new seismic image highlights the details of the subsoil reflectors and allows an easier integration with borehole information and geological surveys than the seismic section obtained by conventional CMP reflection processing. In conclusion, the analysis of S-wave let to characterize the shallow subsurface recognizing levels with limited thickness once we have clearly attenuated ground roll, wind and environmental noise.

Intensified nitrate and phosphorus removal in an electrolysis -integrated horizontal subsurface-flow constructed wetland.

PubMed

Gao, Y; Xie, Y W; Zhang, Q; Wang, A L; Yu, Y X; Yang, L Y

2017-01-01

A novel electrolysis-integrated horizontal subsurface-flow constructed wetland system (E-HFCWs) was developed for intensified removal of nitrogen and phosphorus contaminated water. The dynamics of nitrogen and phosphorus removal and that of main water qualities of inflow and outflow were also evaluated. The hydraulic retention time (HRT) greatly enhanced nitrate removal when the electrolysis current intensity was stabilized at 0.07 mA/cm 2 . When the HRT ranged from 2 h to 12 h, the removal rate of nitrate increased from 20% to 84%. Phosphorus (P) removal was also greatly enhanced-exceeding 90% when the HRT was longer than 4 h in the electrolysis-integrated HFCWs. This improved P removal is due to the in-situ formation of ferric ions by anodizing of sacrificial iron anodes, causing chemical precipitation, physical adsorption and flocculation of phosphorus. Thus, electrolysis plays an important role in nitrate and phosphorus removal. The diversity and communities of bacteria in the biofilm of substrate was established by the analysis of 16S rDNA gene sequences, and the biofilm was abundant with Comamonadaceae and Xanthomonadaceae bacteria in E-HFCWs. Test results illustrated that the electrolysis integrated with horizontal subsurface-flow constructed wetland is a feasible and effective technology for intensified nitrogen and phosphorus removal. Copyright © 2016. Published by Elsevier Ltd.

Soil Carbon Dioxide Production and Surface Fluxes: Subsurface Physical Controls

NASA Astrophysics Data System (ADS)

Risk, D.; Kellman, L.; Beltrami, H.

Soil respiration is a critical determinant of landscape carbon balance. Variations in soil temperature and moisture patterns are important physical processes controlling soil respiration which need to be better understood. Relationships between soil respi- ration and physical controls are typically addressed using only surface flux data but other methods also exist which permit more rigorous interpretation of soil respira- tion processes. Here we use a combination of subsurface CO_{2} concentrations, surface CO_{2} fluxes and detailed physical monitoring of the subsurface envi- ronment to examine physical controls on soil CO_{2} production at four climate observatories in Eastern Canada. Results indicate that subsurface CO_{2} produc- tion is more strongly correlated to the subsurface thermal environment than the surface CO_{2} flux. Soil moisture was also found to have an important influence on sub- surface CO_{2} production, particularly in relation to the soil moisture - soil profile diffusivity relationship. Non-diffusive profile CO_{2} transport appears to be im- portant at these sites, resulting in a de-coupling of summertime surface fluxes from subsurface processes and violating assumptions that surface CO_{2} emissions are the result solely of diffusion. These results have implications for the study of soil respiration across a broad range of terrestrial environments.

Integrating wireless sensor network for monitoring subsidence phenomena

NASA Astrophysics Data System (ADS)

Marturià, Jordi; Lopez, Ferran; Gigli, Giovanni; Intrieri, Emanuele; Mucchi, Lorenzo; Fornaciai, Alessandro

2016-04-01

An innovative wireless sensor network (WSN) for the 3D superficial monitoring of deformations (such as landslides and subsidence) is being developed in the frame of the Wi-GIM project (Wireless sensor network for Ground Instability Monitoring - LIFE12 ENV/IT/001033). The surface movement is detected acquiring the position (x, y and z) by integrating large bandwidth technology able to detect the 3D coordinates of the sensor with a sub-meter error, with continuous wave radar, which allows decreasing the error down to sub-cm. The Estació neighborhood in Sallent is located over the old potassium mine Enrique. This zone has been affected by a subsidence process over more than twenty years. The implementation of a wide network for ground auscultation has allowed monitoring the process of subsidence since 1997. This network consists of: i) a high-precision topographic leveling network to control the subsidence in surface; ii) a rod extensometers network to monitor subsurface deformation; iii) an automatic Leica TCA Total Station to monitor building movements; iv) an inclinometers network to measure the horizontal displacements on subsurface and v) a piezometer to measure the water level. Those networks were implemented within an alert system for an organized an efficient response of the civil protection authorities in case of an emergency. On 23rd December 2008, an acceleration of subsoil movements (of approx. 12-18 cm/year) provoked the activation of the emergency plan by the Catalan Civil Protection. This implied the preventive and scheduled evacuation of the neighbours (January 2009) located in the area with a higher risk of collapse: around 120 residents of 43 homes. As a consequence, the administration implemented a compensation plan for the evacuation of the whole neighbourhood residents and the demolition of 405 properties. In this work, the adaptation and integration process of Wi-GIM system with those conventional monitoring network are presented for its testing and evaluation. The knowledge gained in the subsidence process, complemented by the huge availability of data from existing networks constitutes a solid foundation for achieving those objectives. New monitoring points have been identified, constructed, prepared to integrate the conventional monitoring system with Wi-GIM system to build a robust system compatible with WI-GIM requirements.

Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants

PubMed Central

Uddin, M S; Hall, Colin; Murphy, Peter

2015-01-01

Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes—conversion and deposition coatings—while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches are required to leverage the benefit of Mg-based alloys. Hybrid treatments combining innovative biomimetic coating and mechanical processing would be regarded as a potentially promising way to tackle the corrosion problem. Synergetic cutting-burnishing integrated with cryogenic cooling may be another encouraging approach in this regard. More studies focusing on rigorous testing, evaluation and characterisation are needed to assess the efficacy of the methods. PMID:27877829

MA_MISS: Mars Multispectral Imager for Subsurface Studies

NASA Astrophysics Data System (ADS)

De Sanctis, M. C.; Coradini, A.; Ammannito, E.; Boccaccini, A.; Di Iorio, T.; Battistelli, E.; Capanni, A.

2012-04-01

A Drilling system, coupled with an in situ analysis package, is installed on the ExoMars Pasteur Rover to perform in situ investigations up to 2m in the Mars soil. Ma_Miss (Mars Multispectral Imager for Subsurface Studies) is a spectrometer devoted to observe the lateral wall of the borehole generated by the Drilling system. The instrument is fully integrated with the Drill and shares its structure and electronics. For the first time in Mars exploration experiments the water/geochemical environment will be investigated as function of depth in the shallow subsurface. Samples from the subsurface of Martian soil are unaltered by weathering process, oxidation and erosion. Subsurface access can be the key to look for signs of present and past environmental conditions, associated to the possibility for life (water, volatiles and weathering process). The analysis of uncontaminated samples by means of instrumented Drill and in situ observations is the solution for unambiguous interpretation of the original environment that leading to the formation of rocks. Ma_Miss experiment is perfectly suited to perform multispectral imaging of the drilled layers. Ma_Miss is a miniaturized near-infrared imaging spectrometer in the range 0.4-2.2 µm with 20nm spectral sampling. The task of illuminating the borehole wall and collecting the diffused light from the illuminated spot on the target requires a transparent window on the Drill tool, which shall prevent the dust contamination of the optical and mechanical elements inside. Hardness of sapphire is the closest to diamond one, thus avoiding the risk of scratches on its surface. The Sapphire window is cylindrical, and bounded such as to realize a continuous auger profile. Ma_Miss Optical Head performs the double task of illuminating the borehole wall with a spot around 1 mm diameter and of collecting the scattered light coming from a 0.1 mm diameter spot of the target. The signal from the Optical Head to the spectrometer is transferred through the different elements of the Drill by means of fiber optics and an optical rotary joint implemented in the roto-translation group of the Drill. Ma_Miss Optical Head has been tested in the breadboard to capture the diffused light from the observed target and transfer the signal to a laboratory spectrometer for analysis. The Optical Head of Ma_Miss has been tested after integration in ExoMars Drill. The drilling experiment has been carried out in realistic media (tuff, red brick). The test shows good performance of Optical Head illumination capability and of the window cleanliness during the drilling. Illumination spot is focused at the nominal distance of 0.2 mm from the sapphire window. During the ExoMars Pasteur Rover mission, the Ma_Miss experiment will allow collecting valuable data of the drilled stratigraphic column, will document "in-situ" the nature of the samples that will be delivered to the Pasteur Laboratory and will be able to identify hydrated minerals, sedimentary materials and different kind of diagnostic materials of Martian subsurface.

Imaging of Subsurface Corrosion Using Gradient-Field Pulsed Eddy Current Probes with Uniform Field Excitation

PubMed Central

Ren, Shuting; Yan, Bei; Zainal Abidin, Ilham Mukriz; Wang, Yi

2017-01-01

A corrosive environment leaves in-service conductive structures prone to subsurface corrosion which poses a severe threat to the structural integrity. It is indispensable to detect and quantitatively evaluate subsurface corrosion via non-destructive evaluation techniques. Although the gradient-field pulsed eddy current technique (GPEC) has been found to be superior in the evaluation of corrosion in conductors, it suffers from a technical drawback resulting from the non-uniform field excited by the conventional pancake coil. In light of this, a new GPEC probe with uniform field excitation for the imaging of subsurface corrosion is proposed in this paper. The excited uniform field makes the GPEC signal correspond only to the field perturbation due to the presence of subsurface corrosion, which benefits the corrosion profiling and sizing. A 3D analytical model of GPEC is established to analyze the characteristics of the uniform field induced within a conductor. Following this, experiments regarding the imaging of subsurface corrosion via GPEC have been carried out. It has been found from the results that the proposed GPEC probe with uniform field excitation not only applies to the imaging of subsurface corrosion in conductive structures, but provides high-sensitivity imaging results regarding the corrosion profile and opening size. PMID:28758985

Imaging of Subsurface Corrosion Using Gradient-Field Pulsed Eddy Current Probes with Uniform Field Excitation.

PubMed

Li, Yong; Ren, Shuting; Yan, Bei; Zainal Abidin, Ilham Mukriz; Wang, Yi

2017-07-31

A corrosive environment leaves in-service conductive structures prone to subsurface corrosion which poses a severe threat to the structural integrity. It is indispensable to detect and quantitatively evaluate subsurface corrosion via non-destructive evaluation techniques. Although the gradient-field pulsed eddy current technique (GPEC) has been found to be superior in the evaluation of corrosion in conductors, it suffers from a technical drawback resulting from the non-uniform field excited by the conventional pancake coil. In light of this, a new GPEC probe with uniform field excitation for the imaging of subsurface corrosion is proposed in this paper. The excited uniform field makes the GPEC signal correspond only to the field perturbation due to the presence of subsurface corrosion, which benefits the corrosion profiling and sizing. A 3D analytical model of GPEC is established to analyze the characteristics of the uniform field induced within a conductor. Following this, experiments regarding the imaging of subsurface corrosion via GPEC have been carried out. It has been found from the results that the proposed GPEC probe with uniform field excitation not only applies to the imaging of subsurface corrosion in conductive structures, but provides high-sensitivity imaging results regarding the corrosion profile and opening size.

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.

Upper ocean climate of the Eastern Mediterranean Sea during the Holocene Insolation Maximum - a model study

NASA Astrophysics Data System (ADS)

Adloff, F.; Mikolajewicz, U.; Kucera, M.; Grimm, R.; Maier-Reimer, E.; Schmiedl, G.; Emeis, K.

2011-05-01

Nine thousand years ago, the Northern Hemisphere experienced enhanced seasonality caused by an orbital configuration with a minimum of the precession index. To assess the impact of the "Holocene Insolation Maximum" (HIM) on the Mediterranean Sea, we use a regional ocean general circulation model forced by atmospheric input derived from global simulations. A stronger seasonal cycle is simulated in the model, which shows a relatively homogeneous winter cooling and a summer warming with well-defined spatial patterns, in particular a subsurface warming in the Cretan and Western Levantine areas. The comparison between the SST simulated for the HIM and the reconstructions from planktonic foraminifera transfer functions shows a poor agreement, especially for summer, when the vertical temperature gradient is strong. However, a reinterpretation of the reconstructions is proposed, to consider the conditions throughout the upper water column. Such a depth-integrated approach accounts for the vertical range of preferred habitat depths of the foraminifera used for the reconstructions and strongly improves the agreement between modelled and reconstructed temperature signal. The subsurface warming is recorded by both model and proxies, with a light shift to the south in the model results. The mechanisms responsible for the peculiar subsurface pattern are found to be a combination of enhanced downwelling and wind mixing due to strengthened Etesian winds, and enhanced thermal forcing due to the stronger summer insolation in the Northern Hemisphere. Together, these processes induce a stronger heat transfer from the surface to the subsurface during late summer in the Western Levantine; this leads to an enhanced heat piracy in this region.

Impact of mercury on denitrification and denitrifying microbial communities in nitrate enrichments of subsurface sediments.

PubMed

Wang, Yanping; Wiatrowski, Heather A; John, Ria; Lin, Chu-Ching; Young, Lily Y; Kerkhof, Lee J; Yee, Nathan; Barkay, Tamar

2013-02-01

The contamination of groundwater with mercury (Hg) is an increasing problem worldwide. Yet, little is known about the interactions of Hg with microorganisms and their processes in subsurface environments. We tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge Integrated Field Research Challenge site, where nitrate is a major contaminant and where bioremediation efforts are in progress. We observed an inverse relationship between Hg concentrations and onset and rates of denitrification in nitrate enrichment cultures containing between 53 and 1.1 μM of inorganic Hg; higher Hg concentrations increasingly extended the time to onset of denitrification and inhibited denitrification rates. Microbial community complexity, as indicated by terminal restriction fragment length polymorphism (tRFLP) analysis of the 16S rRNA genes, declined with increasing Hg concentrations; at the 312 nM Hg treatment, a single tRFLP peak was detected representing a culture of Bradyrhizobium sp. that possessed the merA gene indicating a potential for Hg reduction. A culture identified as Bradyrhizobium sp. strain FRC01 with an identical 16S rRNA sequence to that of the enriched peak in the tRFLP patterns, reduced Hg(II) to Hg(0) and carried merA whose amino acid sequence has 97 % identity to merA from the Proteobacteria and Firmicutes. This study demonstrates that in subsurface sediment incubations, Hg may inhibit denitrification and that inhibition may be alleviated when Hg resistant denitrifying Bradyrhizobium spp. detoxify Hg by its reduction to the volatile elemental form.

VNIR spectroscopy of Mars Analogues with the ExoMars-Ma_Miss instrument .

NASA Astrophysics Data System (ADS)

De Angelis, S.; De Sanctis, M. C.; Ammannito, E.; Di Iorio, T.; Carli, C.; Frigeri, A.; Capria, M. T.; Federico, C.; Boccaccini, A.; Capaccioni, F.; Giardino, M.; Cerroni, P.; Palomba, E.; Piccioni, G.

The ExoMars 2018 mission will investigate the Martian surface environment with the aim of searching for eventual present or past signs of life, and to obtain a characterization of Martian soil and subsoil. The investigation of the near-surface environment and of the shallow subsurface with complementary techniques, will provide insights on the chemical and mineralogical composition, material grain size, the litotypes, the stratigraphy: these information will help us to understand the geologic processes that characterized the history of the Martian crust. The Ma_Miss (Mars Multispectral Imager for Subsurface Studies) instrument \\citep{coradini01} is a miniaturized visible and near-infrared spectrometer, integrated in the ExoMars Pasteur Rover Drill: it will acquire spectra of the borehole wall performed by the Drill, down to a depth up to two meters. Spectroscopic tests have been performed with the laboratory model (breadboard) on spectral targets and rock samples; furtherly, an activity of VNIR reflectance spectroscopy of Mars analogues has been begun with the breadboard to build a spectral library.

Detailed 3D Geophysical Model of the Shallow Subsurface (Zancara River Basin, Iberian Peninsula)

NASA Astrophysics Data System (ADS)

Carbonell, R.; Marzán, I.; Martí, D.; Lobo, A.; Jean, K.; Alvarez-Marrón, J.

2016-12-01

Detailed knowledge of the structure and lithologies of the shallow subsurface is required when designing and building singular geological storage facilities this is the case of the study area in Villar de Cañas (Cuenca, Central Spain). In which an extensive multidisciplinary data acquisition program has been carried out. This include studies on: geology, hydrology, geochemistry, geophysics, borehole logging, etc. Because of this data infrastructure, it can be considered a subsurface imaging laboratory to test and validate indirect underground characterization approaches. The field area is located in a Miocene syncline within the Záncara River Basin (Cuenca, Spain). The sedimentary sequence consists in a transition from shales to massive gypsums, and underlying gravels. The stratigraphic succession features a complex internal structure, diffused lithological boundaries and relatively large variability of properties within the same lithology, these makes direct geological interpretation very difficult and requires of the integration of all the measured physical properties. The ERT survey, the seismic tomography data and the logs have been used jointly to build a 3-D multi-parameter model of the subsurface in a surface of 500x500 m. The Vp model (a 10x20x5 m grid) is able to map the high velocities of the massive gypsum, however it was neither able to map the details of the shale-gypsm transition (low velocity contrast) nor to differentiate the outcropping altered gypsum from the weathered shales. The integration of the electrical resistivity and the log data by means of a supervised statistical tools (Linear Discriminant Analysis, LDA) resulted in a new 3D multiparametric subsurface model. This new model integrates the different data sets resolving the uncertainties characteristic of the models obtained independently by the different techniques separately. Furthermore, this test seismic dataset has been used to test FWI approaches in order to study their capacities. (Research supports: CGL2014-56548-P, 2009-SGR-1595, CGL2013-47412-C2-1-P).

Modeling Subsurface Behavior at the System Level: Considerations and a Path Forward

NASA Astrophysics Data System (ADS)

Geesey, G.

2005-12-01

The subsurface is an obscure but essential resource to life on Earth. It is an important region for carbon production and sequestration, a source and reservoir for energy, minerals and metals and potable water. There is a growing need to better understand subsurface possesses that control the exploitation and security of these resources. Our best models often fail to predict these processes at the field scale because of limited understanding of 1) the processes and the controlling parameters, 2) how processes are coupled at the field scale 3) geological heterogeneities that control hydrological, geochemical and microbiological processes at the field scale and 4) lack of data sets to calibrate and validate numerical models. There is a need for experimental data obtained at scales larger than those obtained at the laboratory bench that take into account the influence of hydrodynamics, geochemical reactions including complexation and chelation/adsorption/precipitation/ion exchange/oxidation-reduction/colloid formation and dissolution, and reactions of microbial origin. Furthermore, the coupling of each of these processes and reactions needs to be evaluated experimentally at a scale that produces data that can be used to calibrate numerical models so that they accurately describe field scale system behavior. Establishing the relevant experimental scale for collection of data from coupled processes remains a challenge and will likely be process-dependent and involve iterations of experimentation and data collection at different intermediate scales until the models calibrated with the appropriate date sets achieve an acceptable level of performance. Assuming that the geophysicists will soon develop technologies to define geological heterogeneities over a wide range of scales in the subsurface, geochemists need to continue to develop techniques to remotely measure abiotic reactions, while geomicrobiologists need to continue their development of complementary technologies to remotely measure microbial community parameters that define their key functions at a scale that accurately reflects their role in large scale subsurface system behavior. The practical questions that geomicrobiologist must answer in the short term are: 1) What is known about the activities of the dominant microbial populations or those of their closest relatives? 2) Which of these activities is likely to dominate under in situ conditions? In the process of answering these questions, researchers will obtain answers to questions of a more fundamental nature such as 1) How deep does "active" life extend below the surface of the seafloor and terrestrial subsurface? 2) How are electrons exchanged between microbial cells and solid phase minerals? 3) What is the metabolic state and mechanism of survival of "inactive" life forms in the subsurface? 4) What can genomes of life forms trapped in geological material tell us about evolution of life that current methods cannot? The subsurface environment represents a challenging environment to understand and model. As the need to understand subsurface processes increases and the technologies to characterize them become available, modeling subsurface behavior will approach the level of sophistication of models used today to predict behavior of other large scale systems such as the oceans.

Subsurface drainage erodes forested granitic terrane

Treesearch

Philip Durgin

1984-01-01

Abstract - Solution and landsliding, the dominant erosion processes in undisturbed forested mountainous watersheds, are both influenced by subsurface drainage. Biological processes that generate organic acids accelerate loss of dissolved solids by promoting the dissolution of primary minerals in granitic rock. These organic acids can also disperse the secondary...

Spot restoration for GPR image post-processing

DOEpatents

Paglieroni, David W; Beer, N. Reginald

2014-05-20

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Integrated system for gathering, processing, and reporting data relating to site contamination

DOEpatents

Long, D.D.; Goldberg, M.S.; Baker, L.A.

1997-11-11

An integrated screening system comprises an intrusive sampling subsystem, a field mobile laboratory subsystem, a computer assisted design/geographical information subsystem, and a telecommunication linkup subsystem, all integrated to provide synergistically improved data relating to the extent of site soil/groundwater contamination. According to the present invention, data samples related to the soil, groundwater or other contamination of the subsurface material are gathered and analyzed to measure contaminants. Based on the location of origin of the samples in three-dimensional space, the analyzed data are transmitted to a location display. The data from analyzing samples and the data from the locating the origin are managed to project the next probable sample location. The next probable sample location is then forwarded for use as a guide in the placement of ensuing sample location, whereby the number of samples needed to accurately characterize the site is minimized. 10 figs.

Integrated system for gathering, processing, and reporting data relating to site contamination

DOEpatents

Long, Delmar D.; Goldberg, Mitchell S.; Baker, Lorie A.

1997-01-01

An integrated screening system comprises an intrusive sampling subsystem, a field mobile laboratory subsystem, a computer assisted design/geographical information subsystem, and a telecommunication linkup subsystem, all integrated to provide synergistically improved data relating to the extent of site soil/groundwater contamination. According to the present invention, data samples related to the soil, groundwater or other contamination of the subsurface material are gathered and analyzed to measure contaminants. Based on the location of origin of the samples in three-dimensional space, the analyzed data are transmitted to a location display. The data from analyzing samples and the data from the locating the origin are managed to project the next probable sample location. The next probable sample location is then forwarded for use as a guide in the placement of ensuing sample location, whereby the number of samples needed to accurately characterize the site is minimized.

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.

Synoptic-to-planetary scale wind variability enhances phytoplankton biomass at ocean fronts

NASA Astrophysics Data System (ADS)

Whitt, D. B.; Taylor, J. R.; Lévy, M.

2017-06-01

In nutrient-limited conditions, phytoplankton growth at fronts is enhanced by winds, which drive upward nutrient fluxes via enhanced turbulent mixing and upwelling. Hence, depth-integrated phytoplankton biomass can be 10 times greater at isolated fronts. Using theory and two-dimensional simulations with a coupled physical-biogeochemical ocean model, this paper builds conceptual understanding of the physical processes driving upward nutrient fluxes at fronts forced by unsteady winds with timescales of 4-16 days. The largest vertical nutrient fluxes occur when the surface mixing layer penetrates the nutricline, which fuels phytoplankton in the mixed layer. At a front, mixed layer deepening depends on the magnitude and direction of the wind stress, cross-front variations in buoyancy and velocity at the surface, and potential vorticity at the base of the mixed layer, which itself depends on past wind events. Consequently, mixing layers are deeper and more intermittent in time at fronts than outside fronts. Moreover, mixing can decouple in time from the wind stress, even without other sources of physical variability. Wind-driven upwelling also enhances depth-integrated phytoplankton biomass at fronts; when the mixed layer remains shallower than the nutricline, this results in enhanced subsurface phytoplankton. Oscillatory along-front winds induce both oscillatory and mean upwelling. The mean effect of oscillatory vertical motion is to transiently increase subsurface phytoplankton over days to weeks, whereas slower mean upwelling sustains this increase over weeks to months. Taken together, these results emphasize that wind-driven phytoplankton growth is both spatially and temporally intermittent and depends on a diverse combination of physical processes.

On the value of surface saturated area dynamics mapped with thermal infrared imagery for modeling the hillslope-riparian-stream continuum

NASA Astrophysics Data System (ADS)

Glaser, Barbara; Klaus, Julian; Frei, Sven; Frentress, Jay; Pfister, Laurent; Hopp, Luisa

2016-10-01

The highly dynamic processes within a hillslope-riparian-stream (HRS) continuum are known to affect streamflow generation, but are yet not fully understood. Within this study, we simulated a headwater HRS continuum in western Luxembourg with an integrated hydrologic surface subsurface model (HydroGeoSphere). The model was setup with thorough consideration of catchment-specific attributes and we performed a multicriteria model evaluation (4 years) with special focus on the temporally varying spatial patterns of surface saturation. We used a portable thermal infrared (TIR) camera to map surface saturation with a high spatial resolution and collected 20 panoramic snapshots of the riparian zone (approx. 10 m × 20 m) under different hydrologic conditions. Qualitative and quantitative comparison of the processed TIR panoramas and the corresponding model output panoramas revealed a good agreement between spatiotemporal dynamic model and field surface saturation patterns. A double logarithmic linear relationship between surface saturation extent and discharge was similar for modeled and observed data. This provided confidence in the capability of an integrated hydrologic surface subsurface model to represent temporal and spatial water flux dynamics at small (HRS continuum) scales. However, model scenarios with different parameterizations of the riparian zone showed that discharge and surface saturation were controlled by different parameters and hardly influenced each other. Surface saturation only affected very fast runoff responses with a small volumetric contribution to stream discharge, indicating that the dynamic surface saturation in the riparian zone does not necessarily imply a major control on runoff generation.

Gas injection to inhibit migration during an in situ heat treatment process

DOEpatents

Kuhlman, Myron Ira; Vinegar; Harold J.; Baker, Ralph Sterman; Heron, Goren

2010-11-30

Methods of treating a subsurface formation are described herein. Methods for treating a subsurface treatment area in a formation may include introducing a fluid into the formation from a plurality of wells offset from a treatment area of an in situ heat treatment process to inhibit outward migration of formation fluid from the in situ heat treatment process.

3D modeling of a dolerite intrusion from the photogrammetric and geophysical data integration.

NASA Astrophysics Data System (ADS)

Duarte, João; Machadinho, Ana; Figueiredo, Fernando; Mira, Maria

2015-04-01

The aims of this study is create a methodology based on the integration of data obtained from various available technologies, which allow a credible and complete evaluation of rock masses. In this particular case of a dolerite intrusion, which deployed an exploration of aggregates and belongs to the Jobasaltos - Extracção e Britagem. S.A.. Dolerite intrusion is situated in the volcanic complex of Serra de Todo-o-Mundo, Casais Gaiola, intruded in Jurassic sandstones. The integration of the surface and subsurface mapping, obtained by technology UAVs (Drone) and geophysical surveys (Electromagnetic Method - TEM 48 FAST), allows the construction of 2D and 3D models of the study local. The combination of the 3D point clouds produced from two distinct processes, modeling of photogrammetric and geophysical data, will be the basis for the construction of a single model of set. The rock masses in an integral perspective being visible their development above the surface and subsurface. The presentation of 2D and 3D models will give a perspective of structures, fracturation, lithology and their spatial correlations contributing to a better local knowledge, as well as its potential for the intended purpose. From these local models it will be possible to characterize and quantify the geological structures. These models will have its importance as a tool to assist in the analysis and drafting of regional models. The qualitative improvement in geological/structural modeling, seeks to reduce the value of characterization/cost ratio, in phase of prospecting, improving the investment/benefit ratio. This methodology helps to assess more accurately the economic viability of the projects.

Gypsies in the palace: Experimentalist's view on the use of 3-D physics-based simulation of hillslope hydrological response

USGS Publications Warehouse

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

2010-01-01

As a fundamental unit of the landscape, hillslopes are studied for their retention and release of water and nutrients across a wide range of ecosystems. The understanding of these near-surface processes is relevant to issues of runoff generation, groundwater-surface water interactions, catchment export of nutrients, dissolved organic carbon, contaminants (e.g. mercury) and ultimately surface water health. We develop a 3-D physics-based representation of the Panola Mountain Research Watershed experimental hillslope using the TOUGH2 sub-surface flow and transport simulator. A recent investigation of sub-surface flow within this experimental hillslope has generated important knowledge of threshold rainfall-runoff response and its relation to patterns of transient water table development. This work has identified components of the 3-D sub-surface, such as bedrock topography, that contribute to changing connectivity in saturated zones and the generation of sub-surface stormflow. Here, we test the ability of a 3-D hillslope model (both calibrated and uncalibrated) to simulate forested hillslope rainfall-runoff response and internal transient sub-surface stormflow dynamics. We also provide a transparent illustration of physics-based model development, issues of parameterization, examples of model rejection and usefulness of data types (e.g. runoff, mean soil moisture and transient water table depth) to the model enterprise. Our simulations show the inability of an uncalibrated model based on laboratory and field characterization of soil properties and topography to successfully simulate the integrated hydrological response or the distributed water table within the soil profile. Although not an uncommon result, the failure of the field-based characterized model to represent system behaviour is an important challenge that continues to vex scientists at many scales. We focus our attention particularly on examining the influence of bedrock permeability, soil anisotropy and drainable porosity on the development of patterns of transient groundwater and sub-surface flow. Internal dynamics of transient water table development prove to be essential in determining appropriate model parameterization. ?? 2010 John Wiley & Sons, Ltd.

Integrating aeromagnetic and Landsat™ 8 data into subsurface structural mapping of Precambrian basement complex

NASA Astrophysics Data System (ADS)

Kayode, John Stephen; Nawawi, M. N. M.; Abdullah, Khiruddin B.; Khalil, Amin E.

2017-01-01

The integration of Aeromagnetic data and remotely sensed imagery with the intents of mapping the subsurface geological structures in part of the South-western basement complex of Nigeria was developed using the PCI Geomatica Software. 2013. The data obtained from the Nigerian Geological Survey Agency; was corrected using Regional Residual Separation of the Total Magnetic field anomalies enhanced, and International Geomagnetic Reference Field removed. The principal objective of this study is, therefore, to introduce a rapid and efficient method of subsurface structural depth estimate and structural index evaluation through the incorporation of the Euler Deconvolution technique into PCI Geomatica 2013 to prospect for subsurface geological structures. The shape and depth of burial helped to define these structures from the regional aeromagnetic map. The method enabled various structural indices to be automatically delineated for an index of between 0.5 SI and 3.0 SI at a maximum depth of 1.1 km that clearly showed the best depths estimate for all the structural indices. The results delineate two major magnetic belts in the area; the first belt shows an elongated ridge-like structure trending mostly along the NorthNortheast-SouthSouthwest and the other anomalies trends primarily in the Northeast, Northwest, Northeast-Southwest parts of the study area that could be attributed to basement complex granitic intrusions from the tectonic history of the area. The majority of the second structures showed various linear structures different from the first structure. Basically, a significant offset was delineated at the core segment of the study area, suggesting a major subsurface geological feature that controls mineralisation in this area.

PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data

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

Johnson, Timothy C.; Hammond, Glenn E.; Chen, Xingyuan

Time-lapse electrical resistivity tomography (ERT) is finding increased application for remotely monitoring processes occurring in the near subsurface in three-dimensions (i.e. 4D monitoring). However, there are few codes capable of simulating the evolution of subsurface resistivity and corresponding tomographic measurements arising from a particular process, particularly in parallel and with an open source license. Herein we describe and demonstrate an electrical resistivity tomography module for the PFLOTRAN subsurface simulation code, named PFLOTRAN-E4D. The PFLOTRAN-E4D module operates in parallel using a dedicated set of compute cores in a master-slave configuration. At each time step, the master processes receives subsurface states frommore » PFLOTRAN, converts those states to bulk electrical conductivity, and instructs the slave processes to simulate a tomographic data set. The resulting multi-physics simulation capability enables accurate feasibility studies for ERT imaging, the identification of the ERT signatures that are unique to a given process, and facilitates the joint inversion of ERT data with hydrogeological data for subsurface characterization. PFLOTRAN-E4D is demonstrated herein using a field study of stage-driven groundwater/river water interaction ERT monitoring along the Columbia River, Washington, USA. Results demonstrate the complex nature of changes subsurface electrical conductivity, in both the saturated and unsaturated zones, arising from water table changes and from river water intrusion into the aquifer. The results also demonstrate the sensitivity of surface based ERT measurements to those changes over time. PFLOTRAN-E4D is available with the PFLOTRAN development version with an open-source license at https://bitbucket.org/pflotran/pflotran-dev .« less

PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data

NASA Astrophysics Data System (ADS)

Johnson, Timothy C.; Hammond, Glenn E.; Chen, Xingyuan

2017-02-01

Time-lapse electrical resistivity tomography (ERT) is finding increased application for remotely monitoring processes occurring in the near subsurface in three-dimensions (i.e. 4D monitoring). However, there are few codes capable of simulating the evolution of subsurface resistivity and corresponding tomographic measurements arising from a particular process, particularly in parallel and with an open source license. Herein we describe and demonstrate an electrical resistivity tomography module for the PFLOTRAN subsurface flow and reactive transport simulation code, named PFLOTRAN-E4D. The PFLOTRAN-E4D module operates in parallel using a dedicated set of compute cores in a master-slave configuration. At each time step, the master processes receives subsurface states from PFLOTRAN, converts those states to bulk electrical conductivity, and instructs the slave processes to simulate a tomographic data set. The resulting multi-physics simulation capability enables accurate feasibility studies for ERT imaging, the identification of the ERT signatures that are unique to a given process, and facilitates the joint inversion of ERT data with hydrogeological data for subsurface characterization. PFLOTRAN-E4D is demonstrated herein using a field study of stage-driven groundwater/river water interaction ERT monitoring along the Columbia River, Washington, USA. Results demonstrate the complex nature of subsurface electrical conductivity changes, in both the saturated and unsaturated zones, arising from river stage fluctuations and associated river water intrusion into the aquifer. The results also demonstrate the sensitivity of surface based ERT measurements to those changes over time. PFLOTRAN-E4D is available with the PFLOTRAN development version with an open-source license at https://bitbucket.org/pflotran/pflotran-dev.

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.

Total water storage dynamics derived from tree-ring records and terrestrial gravity observations

NASA Astrophysics Data System (ADS)

Creutzfeldt, Benjamin; Heinrich, Ingo; Merz, Bruno

2015-10-01

For both societal and ecological reasons, it is important to understand past and future subsurface water dynamics but estimating subsurface water storage is notoriously difficult. In this pilot study, we suggest the reconstruction of subsurface water dynamics by a multi-disciplinary approach combining hydrology, dendrochronology and geodesy. In a first step, nine complete years of high-precision gravimeter observations are used to estimate water storage changes in the subsurface at the Geodetic Observatory Wettzell in the Bavarian Forest, Germany. The record is extended to 63 years by calibrating a hydrological model against the 9 years of gravimeter observations. The relationship between tree-ring growth and water storage changes is evaluated as well as that between tree-ring growth and supplementary hydro-meteorological data. Results suggest that tree-ring growth is influenced primarily by subsurface water storage. Other variables related to the overall moisture status (e.g., Standardized Precipitation Index, Palmer Drought Severity Index, streamflow) are also strongly correlated with tree-ring width. While these indices are all indicators of water stored in the landscape, water storage changes of the subsurface estimated by depth-integral measurements give us the unique opportunity to directly reconstruct subsurface water storage dynamics from records of tree-ring width. Such long reconstructions will improve our knowledge of past water storage variations and our ability to predict future developments. Finally, knowing the relationship between subsurface storage dynamics and tree-ring growth improves the understanding of the different signal components contained in tree-ring chronologies.

Integrated geoelectrical survey for groundwater and shallow subsurface evaluation: case study at Siliyin spring, El-Fayoum, Egypt

NASA Astrophysics Data System (ADS)

Metwaly, Mohamed; El-Qady, Gad; Massoud, Usama; El-Kenawy, Abeer; Matsushima, Jun; Al-Arifi, Nasser

2010-09-01

Siliyin spring is one of the many natural fresh water springs in the Western Desert of Egypt. It is located at the central part of El-Fayoum Delta, which is a potential place for urban developments and touristic activities. Integrated geoelectrical survey was conducted to facilitate mapping the groundwater resources and the shallow subsurface structures in the area. Twenty-eight transient electromagnetic (TEM) soundings, three vertical electrical soundings (VES) and three electrical resistivity tomography (ERT) profiles were carried out around the Siliyin spring location. The dense cultivation, the rugged topography and the existence of infra structure in the area hindered acquiring more data. The TEM data were inverted jointly with the VES and ERT, and constrained by available geological information. Based on the inversion results, a set of geoelectrical cross-sections have been constructed. The shallow sand to sandy clay layer that forms the shallow aquifer has been completely mapped underneath and around the spring area. Flowing of water from the Siliyin spring is interconnected with the lateral lithological changes from clay to sand soil. Exploration of the extension of Siliyin spring zone is recommended. The interpretation emphasizes the importance of integrating the geoelectrical survey with the available geological information to obtain useful, cheap and fast lithological and structural subsurface information.

Integrated electromagnetic (EM) and Electrical Resistivity Tomography (ERT) geophysical studies of environmental impact of Awotan dumpsite in Ibadan, southwestern Nigeria

NASA Astrophysics Data System (ADS)

Osinowo, Olawale Olakunle; Falufosi, Michael Oluseyi; Omiyale, Eniola Oluwatosin

2018-04-01

This study attempts to establish the level of contamination caused by the decomposition of wastes by defining the lateral distribution and the vertical limit of leachate induced zone of anomalous conductivity distribution within the subsurface through the analyses of Electromagnetic (EM) and Electrical Resistivity Tomography (ERT) data, generated from the integrated geophysical survey over Awotan landfill dumpsite, in Ibadan, southwest Nigeria. Nine (9) EM and ERT profiles each were established within and around the Awotan landfill site. EM data were acquire at 5 m station interval using 10 m, 20 m and 40 m inter-coil spacings, while ERT stations were occupied at 2 m electrode spacing using dipole-dipole electrode configuration. The near perfect agreement between the two sets of data generated from the EM and ERT surveys over the Awotan landfill site as well as the subsurface imaging ability of these geophysical methods to delineate the region of elevated contamination presented in the form of anomalously high apparent ground conductivity and low subsurface resistivity distribution, suggest the importance of integrating electromagnetic and electrical resistivity investigation techniques for environmental studies and more importantly for selecting appropriate landfill dump site location such with ability to retain the generated contaminants and thus prevent environmental pollution.

The emergence of hydrogeophysics for improved understanding of subsurface processes over multiple scales

DOE PAGES

Binley, Andrew; Hubbard, Susan S.; Huisman, Johan A.; ...

2015-06-15

Geophysics provides a multidimensional suite of investigative methods that are transforming our ability to see into the very fabric of the subsurface environment, and monitor the dynamics of its fluids and the biogeochemical reactions that occur within it. Here we document how geophysical methods have emerged as valuable tools for investigating shallow subsurface processes over the past two decades and offer a vision for future developments relevant to hydrology and also ecosystem science. The field of “hydrogeophysics” arose in the late 1990s, prompted, in part, by the wealth of studies on stochastic subsurface hydrology that argued for better field-based investigativemore » techniques. These new hydrogeophysical approaches benefited from the emergence of practical and robust data inversion techniques, in many cases with a view to quantify shallow subsurface heterogeneity and the associated dynamics of subsurface fluids. Furthermore, the need for quantitative characterization stimulated a wealth of new investigations into petrophysical relationships that link hydrologically relevant properties to measurable geophysical parameters. Development of time-lapse approaches provided a new suite of tools for hydrological investigation, enhanced further with the realization that some geophysical properties may be sensitive to biogeochemical transformations in the subsurface environment, thus opening up the new field of “biogeophysics.” Early hydrogeophysical studies often concentrated on relatively small “plot-scale” experiments. More recently, however, the translation to larger-scale characterization has been the focus of a number of studies. In conclusion, geophysical technologies continue to develop, driven, in part, by the increasing need to understand and quantify key processes controlling sustainable water resources and ecosystem services.« less

The emergence of hydrogeophysics for improved understanding of subsurface processes over multiple scales

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

Binley, Andrew; Hubbard, Susan S.; Huisman, Johan A.

Geophysics provides a multidimensional suite of investigative methods that are transforming our ability to see into the very fabric of the subsurface environment, and monitor the dynamics of its fluids and the biogeochemical reactions that occur within it. Here we document how geophysical methods have emerged as valuable tools for investigating shallow subsurface processes over the past two decades and offer a vision for future developments relevant to hydrology and also ecosystem science. The field of “hydrogeophysics” arose in the late 1990s, prompted, in part, by the wealth of studies on stochastic subsurface hydrology that argued for better field-based investigativemore » techniques. These new hydrogeophysical approaches benefited from the emergence of practical and robust data inversion techniques, in many cases with a view to quantify shallow subsurface heterogeneity and the associated dynamics of subsurface fluids. Furthermore, the need for quantitative characterization stimulated a wealth of new investigations into petrophysical relationships that link hydrologically relevant properties to measurable geophysical parameters. Development of time-lapse approaches provided a new suite of tools for hydrological investigation, enhanced further with the realization that some geophysical properties may be sensitive to biogeochemical transformations in the subsurface environment, thus opening up the new field of “biogeophysics.” Early hydrogeophysical studies often concentrated on relatively small “plot-scale” experiments. More recently, however, the translation to larger-scale characterization has been the focus of a number of studies. In conclusion, geophysical technologies continue to develop, driven, in part, by the increasing need to understand and quantify key processes controlling sustainable water resources and ecosystem services.« less

The emergence of hydrogeophysics for improved understanding of subsurface processes over multiple scales

PubMed Central

Hubbard, Susan S.; Huisman, Johan A.; Revil, André; Robinson, David A.; Singha, Kamini; Slater, Lee D.

2015-01-01

Abstract Geophysics provides a multidimensional suite of investigative methods that are transforming our ability to see into the very fabric of the subsurface environment, and monitor the dynamics of its fluids and the biogeochemical reactions that occur within it. Here we document how geophysical methods have emerged as valuable tools for investigating shallow subsurface processes over the past two decades and offer a vision for future developments relevant to hydrology and also ecosystem science. The field of “hydrogeophysics” arose in the late 1990s, prompted, in part, by the wealth of studies on stochastic subsurface hydrology that argued for better field‐based investigative techniques. These new hydrogeophysical approaches benefited from the emergence of practical and robust data inversion techniques, in many cases with a view to quantify shallow subsurface heterogeneity and the associated dynamics of subsurface fluids. Furthermore, the need for quantitative characterization stimulated a wealth of new investigations into petrophysical relationships that link hydrologically relevant properties to measurable geophysical parameters. Development of time‐lapse approaches provided a new suite of tools for hydrological investigation, enhanced further with the realization that some geophysical properties may be sensitive to biogeochemical transformations in the subsurface environment, thus opening up the new field of “biogeophysics.” Early hydrogeophysical studies often concentrated on relatively small “plot‐scale” experiments. More recently, however, the translation to larger‐scale characterization has been the focus of a number of studies. Geophysical technologies continue to develop, driven, in part, by the increasing need to understand and quantify key processes controlling sustainable water resources and ecosystem services. PMID:26900183

Concentration-discharge relationships to understand the interplay between hydrological and biogeochemical processes: insights from data analysis and numerical experiments in headwater catchments.

NASA Astrophysics Data System (ADS)

De Dreuzy, J. R.; Marçais, J.; Moatar, F.; Minaudo, C.; Courtois, Q.; Thomas, Z.; Longuevergne, L.; Pinay, G.

2017-12-01

Integration of hydrological and biogeochemical processes led to emerging patterns at the catchment scale. Monitoring in rivers reflects the aggregation of these effects. While discharge time series have been measured for decades, high frequency water quality monitoring in rivers now provides prominent measurements to characterize the interplay between hydrological and biogeochemical processes, especially to infer the processes that happen in the heterogeneous subsurface. However, we still lack frameworks to relate observed patterns to specific processes, because of the "organized complexity" of hydrological systems. Indeed, it is unclear what controls, for example, patterns in concentration-discharge (C/Q) relationships due to non-linear processes and hysteresis effects. Here we develop a non-intensive process-based model to test how the integration of different landforms (i.e. geological heterogeneities and structures, topographical features) with different biogeochemical reactivity assumptions (e.g. reactive zone locations) can shape the overall water quality time series. With numerical experiments, we investigate typical patterns in high frequency C/Q relationships. In headwater basins, we found that typical hysteretic patterns in C/Q relationships observed in data time series can be attributed to differences in water and solute locations stored across the hillslope. At the catchment scale though, these effects tend to average out by integrating contrasted hillslopes' landforms. Together these results suggest that information contained in headwater water quality monitoring can be used to understand how hydrochemical processes determine downstream conditions.

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

PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data

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

Johnson, Timothy C.; Hammond, Glenn E.; Chen, Xingyuan

Time-lapse electrical resistivity tomography (ERT) is finding increased application for remotely monitoring processes occurring in the near subsurface in three-dimensions (i.e. 4D monitoring). However, there are few codes capable of simulating the evolution of subsurface resistivity and corresponding tomographic measurements arising from a particular process, particularly in parallel and with an open source license. Herein we describe and demonstrate an electrical resistivity tomography module for the PFLOTRAN subsurface flow and reactive transport simulation code, named PFLOTRAN-E4D. The PFLOTRAN-E4D module operates in parallel using a dedicated set of compute cores in a master-slave configuration. At each time step, the master processesmore » receives subsurface states from PFLOTRAN, converts those states to bulk electrical conductivity, and instructs the slave processes to simulate a tomographic data set. The resulting multi-physics simulation capability enables accurate feasibility studies for ERT imaging, the identification of the ERT signatures that are unique to a given process, and facilitates the joint inversion of ERT data with hydrogeological data for subsurface characterization. PFLOTRAN-E4D is demonstrated herein using a field study of stage-driven groundwater/river water interaction ERT monitoring along the Columbia River, Washington, USA. Results demonstrate the complex nature of subsurface electrical conductivity changes, in both the saturated and unsaturated zones, arising from river stage fluctuations and associated river water intrusion into the aquifer. Furthermore, the results also demonstrate the sensitivity of surface based ERT measurements to those changes over time.« less

PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data

DOE PAGES

Johnson, Timothy C.; Hammond, Glenn E.; Chen, Xingyuan

2016-09-22

Time-lapse electrical resistivity tomography (ERT) is finding increased application for remotely monitoring processes occurring in the near subsurface in three-dimensions (i.e. 4D monitoring). However, there are few codes capable of simulating the evolution of subsurface resistivity and corresponding tomographic measurements arising from a particular process, particularly in parallel and with an open source license. Herein we describe and demonstrate an electrical resistivity tomography module for the PFLOTRAN subsurface flow and reactive transport simulation code, named PFLOTRAN-E4D. The PFLOTRAN-E4D module operates in parallel using a dedicated set of compute cores in a master-slave configuration. At each time step, the master processesmore » receives subsurface states from PFLOTRAN, converts those states to bulk electrical conductivity, and instructs the slave processes to simulate a tomographic data set. The resulting multi-physics simulation capability enables accurate feasibility studies for ERT imaging, the identification of the ERT signatures that are unique to a given process, and facilitates the joint inversion of ERT data with hydrogeological data for subsurface characterization. PFLOTRAN-E4D is demonstrated herein using a field study of stage-driven groundwater/river water interaction ERT monitoring along the Columbia River, Washington, USA. Results demonstrate the complex nature of subsurface electrical conductivity changes, in both the saturated and unsaturated zones, arising from river stage fluctuations and associated river water intrusion into the aquifer. Furthermore, the results also demonstrate the sensitivity of surface based ERT measurements to those changes over time.« less

Radar signal pre-processing to suppress surface bounce and multipath

DOEpatents

Paglieroni, David W; Mast, Jeffrey E; Beer, N. Reginald

2013-12-31

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes that return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Spatially assisted down-track median filter for GPR image post-processing

DOEpatents

Paglieroni, David W; Beer, N Reginald

2014-10-07

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Quantitative subsurface analysis using frequency modulated thermal wave imaging

NASA Astrophysics Data System (ADS)

Subhani, S. K.; Suresh, B.; Ghali, V. S.

2018-01-01

Quantitative depth analysis of the anomaly with an enhanced depth resolution is a challenging task towards the estimation of depth of the subsurface anomaly using thermography. Frequency modulated thermal wave imaging introduced earlier provides a complete depth scanning of the object by stimulating it with a suitable band of frequencies and further analyzing the subsequent thermal response using a suitable post processing approach to resolve subsurface details. But conventional Fourier transform based methods used for post processing unscramble the frequencies with a limited frequency resolution and contribute for a finite depth resolution. Spectral zooming provided by chirp z transform facilitates enhanced frequency resolution which can further improves the depth resolution to axially explore finest subsurface features. Quantitative depth analysis with this augmented depth resolution is proposed to provide a closest estimate to the actual depth of subsurface anomaly. This manuscript experimentally validates this enhanced depth resolution using non stationary thermal wave imaging and offers an ever first and unique solution for quantitative depth estimation in frequency modulated thermal wave imaging.

Performance Indicators for Uranium Bioremediation in the Subsurface: Basis and Assessment

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

Long, Philip E.; Yabusaki, Steven B.

2006-12-29

The purpose of this letter report is to identify performance indicators for in situ engineered bioremediation of subsurface uranium (U) contamination. This report focuses on in situ treatment of groundwater by biostimulation of extant in situ microbial populations (see http://128.3.7.51/NABIR/generalinfo/primers_guides/03_NABIR_primer.pdf for background information on bioremediation of metals and radionuclides). The treatment process involves amendment of the subsurface with an electron donor such as acetate, lactate, ethanol or other organic compound such that in situ microorganisms mediate the reduction of U(VI) to U(IV). U(VI) precipitates as uraninite or other insoluble U phase. Uranium is thus immobilized in place by such processesmore » and is subject to reoxidation that may remobilize the reduced uranium. Related processes include augmenting the extant subsurface microbial populations, addition of electron acceptors, and introduction of chemically reducing materials such as zero-valent Fe. While metrics for such processes may be similar to those for in situ biostimulation, these related processes are not directly in the scope of this letter report.« less

Buried object detection in GPR images

DOEpatents

Paglieroni, David W; Chambers, David H; Bond, Steven W; Beer, W. Reginald

2014-04-29

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Extent and persistence of secondary water quality impacts after enhanced reductive bioremediation

USGS Publications Warehouse

Borden, Robert C.; Jason M. Tillotson,; Ng, Gene-Hua Crystal.; Bekins, Barbara A.; Kent, Douglas B.; Curtis, Gary P.

2017-01-01

Electron donor (ED) addition can be very effective in stimulating enhanced reductive bioremediation (ERB) of a wide variety of groundwater contaminants. However, ERB can result in Secondary Water Quality Impacts (SWQIs) including decreased levels of dissolved oxygen (O2), nitrate (NO3- ), and sulfate (SO42- ), and elevated levels of dissolved manganese (Mn2+), dissolved iron (Fe2+), methane (CH4), sulfide (S2- ), organic carbon, and naturally occurring hazardous compounds (e.g., arsenic). Fortunately, this ‘plume’ of impacted groundwater is usually confined within the original contaminant plume and is unlikely to adversely impact potable water supplies. This report summarizes available information on processes controlling the production and natural attenuation of SWQI parameters and can be used as a guide in understanding the magnitude, areal extent, and duration of SWQIs in ERB treatment zones and the natural attenuation of SWQI parameters as the dissolved solutes migrate downgradient with ambient groundwater flow. This information was compiled from a wide variety of sources including a survey and statistical analysis of SWQIs from 47 ERB sites, geochemical model simulations, field studies at sites where organic-rich materials have entered the subsurface (e.g., wastewater, landfill leachate, and hydrocarbon plumes), and basic information on physical, chemical, and biological processes in the subsurface. This information is then integrated to provide a general conceptual model of the major processes controlling SWQI production and attenuation.

Blueprint for a coupled model of sedimentology, hydrology, and hydrogeology in streambeds

NASA Astrophysics Data System (ADS)

Partington, Daniel; Therrien, Rene; Simmons, Craig T.; Brunner, Philip

2017-06-01

The streambed constitutes the physical interface between the surface and the subsurface of a stream. Across all spatial scales, the physical properties of the streambed control surface water-groundwater interactions. Continuous alteration of streambed properties such as topography or hydraulic conductivity occurs through erosion and sedimentation processes. Recent studies from the fields of ecology, hydrogeology, and sedimentology provide field evidence that sedimentological processes themselves can be heavily influenced by surface water-groundwater interactions, giving rise to complex feedback mechanisms between sedimentology, hydrology, and hydrogeology. More explicitly, surface water-groundwater exchanges play a significant role in the deposition of fine sediments, which in turn modify the hydraulic properties of the streambed. We explore these feedback mechanisms and critically review the extent of current interaction between the different disciplines. We identify opportunities to improve current modeling practices. For example, hydrogeological models treat the streambed as a static rather than a dynamic entity, while sedimentological models do not account for critical catchment processes such as surface water-groundwater exchange. We propose a blueprint for a new modeling framework that bridges the conceptual gaps between sedimentology, hydrogeology, and hydrology. Specifically, this blueprint (1) fully integrates surface-subsurface flows with erosion, transport, and deposition of sediments and (2) accounts for the dynamic changes in surface elevation and hydraulic conductivity of the streambed. Finally, we discuss the opportunities for new research within the coupled framework.

Working Smarter Not Harder - Developing a Virtual Subsurface Data Framework for U.S. Energy R&D

NASA Astrophysics Data System (ADS)

Rose, K.; Baker, D.; Bauer, J.; Dehlin, M.; Jones, T. J.; Rowan, C.

2017-12-01

The data revolution has resulted in a proliferation of resources that span beyond commercial and social networking domains. Research, scientific, and engineering data resources, including subsurface characterization, modeling, and analytical datasets, are increasingly available through online portals, warehouses, and systems. Data for subsurface systems is still challenging to access, discontinuous, and varies in resolution. However, with the proliferation of online data there are significant opportunities to advance access and knowledge of subsurface systems. The Energy Data eXchange (EDX) is an online platform designed to address research data needs by improving access to energy R&D products through advanced search capabilities. In addition, EDX hosts private, virtualized computational workspaces in support of multi-organizational R&D. These collaborative workspaces allow teams to share working data resources and connect to a growing number of analytical tools to support research efforts. One recent application, a team digital data notebook tool, called DataBook, was introduced within EDX workspaces to allow teams to capture contextual and structured data resources. Starting with DOE's subsurface R&D community, the EDX team has been developing DataBook to support scientists and engineers working on subsurface energy research, allowing them to contribute and curate both structured and unstructured data and knowledge about subsurface systems. These resources span petrophysical, geologic, engineering, geophysical, interpretations, models, and analyses associated with carbon storage, water, oil, gas, geothermal, induced seismicity and other subsurface systems to support the development of a virtual subsurface data framework. The integration of EDX and DataBook allows for these systems to leverage each other's best features, such as the ability to interact with other systems (Earthcube, OpenEI.net, NGDS, etc.) and leverage custom machine learning algorithms and capabilities to enhance user experience, make access and connection to relevant subsurface data resources more efficient for research teams to use, analyze and draw insights. Ultimately, the public and private resources in EDX seek to make subsurface energy research more efficient, reduce redundancy, and drive innovation.

A Multi-Scale, Integrated Approach to Representing Watershed Systems

NASA Astrophysics Data System (ADS)

Ivanov, Valeriy; Kim, Jongho; Fatichi, Simone; Katopodes, Nikolaos

2014-05-01

Understanding and predicting process dynamics across a range of scales are fundamental challenges for basic hydrologic research and practical applications. This is particularly true when larger-spatial-scale processes, such as surface-subsurface flow and precipitation, need to be translated to fine space-time scale dynamics of processes, such as channel hydraulics and sediment transport, that are often of primary interest. Inferring characteristics of fine-scale processes from uncertain coarse-scale climate projection information poses additional challenges. We have developed an integrated model simulating hydrological processes, flow dynamics, erosion, and sediment transport, tRIBS+VEGGIE-FEaST. The model targets to take the advantage of the current generation of wealth of data representing watershed topography, vegetation, soil, and landuse, as well as to explore the hydrological effects of physical factors and their feedback mechanisms over a range of scales. We illustrate how the modeling system connects precipitation-hydrologic runoff partition process to the dynamics of flow, erosion, and sedimentation, and how the soil's substrate condition can impact the latter processes, resulting in a non-unique response. We further illustrate an approach to using downscaled climate change information with a process-based model to infer the moments of hydrologic variables in future climate conditions and explore the impact of climate information uncertainty.

Impact of topography on groundwater salinization due to ocean surge inundation

NASA Astrophysics Data System (ADS)

Yu, Xuan; Yang, Jie; Graf, Thomas; Koneshloo, Mohammad; O'Neal, Michael A.; Michael, Holly A.

2016-08-01

Sea-level rise and increases in the frequency and intensity of ocean surges caused by climate change are likely to exacerbate adverse effects on low-lying coastal areas. The landward flow of water during ocean surges introduces salt to surficial coastal aquifers and threatens groundwater resources. Coastal topographic features (e.g., ponds, dunes, barrier islands, and channels) likely have a strong impact on overwash and salinization processes, but are generally highly simplified in modeling studies. To understand topographic impacts on groundwater salinization, we modeled a theoretical overwash event and variable-density groundwater flow and salt transport in 3-D using the fully coupled surface and subsurface numerical simulator, HydroGeoSphere. The model simulates the coastal aquifer as an integrated system considering overland flow, coupled surface and subsurface exchange, variably saturated flow, and variable-density groundwater flow. To represent various coastal landscape types, we simulated both synthetic fields and real-world coastal topography from Delaware, USA. The groundwater salinization assessment suggested that the topographic connectivity promoting overland flow controls the volume of aquifer that is salinized. In contrast, the amount of water that can be stored in surface depressions determines the amount of seawater that infiltrates the subsurface and the time for seawater to flush from the aquifer. Our study suggests that topography has a significant impact on groundwater salinization due to ocean surge overwash, with important implications for coastal land management and groundwater vulnerability assessment.

Subsurface Analysis of the Mesaverde Group on and near the Jicarilla Apache Indian Reservation, New Mexico-its implication on Sites of Oil and Gas Accumulation

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

Ridgley, Jennie

2001-08-21

The purpose of the phase 2 Mesaverde study part of the Department of Energy funded project ''Analysis of oil-bearing Cretaceous Sandstone Hydrocarbon Reservoirs, exclusive of the Dakota Sandstone, on the Jicarilla Apache Indian Reservation, New Mexico'' was to define the facies of the oil-producing units within the subsurface units of the Mesaverde Group and integrate these results with outcrop studies that defined the depositional environments of these facies within a sequence stratigraphic context. The focus of this report will center on (1) integration of subsurface correlations with outcrop correlations of components of the Mesaverde, (2) application of the sequence stratigraphicmore » model determined in the phase one study to these correlations, (3) determination of the facies distribution of the Mesaverde Group and their relationship to sites of oil and gas accumulation, (4) evaluation of the thermal maturity and potential source rocks for oil and gas in the Mesaverde Group, and (5) evaluation of the structural features on the Reservation as they may control sites of oil accumulation.« less

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

Hoak, T.E.; Klawitter, A.L.

Fractured production trends in Piceance Basin Cretaceous-age Mesaverde Group gas reservoirs are controlled by subsurface structures. Because many of the subsurface structures are controlled by basement fault trends, a new interpretation of basement structure was performed using an integrated interpretation of Landsat Thematic Mapper (TM), side-looking airborne radar (SLAR), high altitude, false color aerial photography, gas and water production data, high-resolution aeromagnetic data, subsurface geologic information, and surficial fracture maps. This new interpretation demonstrates the importance of basement structures on the nucleation and development of overlying structures and associated natural fractures in the hydrocarbon-bearing section. Grand Valley, Parachute, Rulison, Plateau,more » Shire Gulch, White River Dome, Divide Creek and Wolf Creek fields all produce gas from fractured tight gas sand and coal reservoirs within the Mesaverde Group. Tectonic fracturing involving basement structures is responsible for development of permeability allowing economic production from the reservoirs. In this context, the significance of detecting natural fractures using the intergrated fracture detection technique is critical to developing tight gas resources. Integration of data from widely-available, relatively inexpensive sources such as high-resolution aeromagnetics, remote sensing imagery analysis and regional geologic syntheses provide diagnostic data sets to incorporate into an overall methodology for targeting fractured reservoirs. The ultimate application of this methodology is the development and calibration of a potent exploration tool to predict subsurface fractured reservoirs, and target areas for exploration drilling, and infill and step-out development programs.« less

On the Angular Variation of Solar Reflectance of Snow

NASA Technical Reports Server (NTRS)

Chang, A. T. C.; Choudhury, B. J.

1979-01-01

Spectral and integrated solar reflectance of nonhomogeneous snowpacks were derived assuming surface reflection of direct radiation and subsurface multiple scattering. For surface reflection, a bidirectional reflectance distribution function derived for an isotropic Gaussian faceted surface was considered and for subsurface multiple scattering, an approximate solution of the radiative transfer equation was studied. Solar radiation incident on the snowpack was decomposed into direct and atmospherically scattered radiation. Spectral attenuation coefficients of ozone, carbon dioxide, water vapor, aerosol and molecular scattering were included in the calculation of incident solar radiation. Illustrative numerical results were given for a case of North American winter atmospheric conditions. The calculated dependence of spectrally integrated directional reflectance (or albedo) on solar elevation was in qualitative agreement with available observations.

A porewater-based stable isotope approach for the investigation of subsurface hydrological processes

NASA Astrophysics Data System (ADS)

Garvelmann, J.; Külls, C.; Weiler, M.

2012-02-01

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 mountainous catchment have been investigated. The H2O(liquid) - H2O(vapor) equilibration laser spectroscopy method was used to obtain high resolution δ2H vertical depth profiles of pore water at various points along two fall lines of a pasture hillslope in the southern Black Forest, Germany. The Porewater-based Stable Isotope Profile (PSIP) approach was developed to use the integrated information of several vertical depth profiles of deuterium along transects at the hillslope. 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 streamwater during base flow conditions indicating the importance of the groundwater component in the catchment. Near the stream indications for efficient mixing of water from lateral subsurface flow paths with vertical percolation are found.

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.

Ma_MISS on ExoMars: Mineralogical Characterization of the Martian Subsurface

NASA Astrophysics Data System (ADS)

De Sanctis, Maria Cristina; Altieri, Francesca; Ammannito, Eleonora; Biondi, David; De Angelis, Simone; Meini, Marco; Mondello, Giuseppe; Novi, Samuele; Paolinetti, Riccardo; Soldani, Massimo; Mugnuolo, Raffaele; Pirrotta, Simone; Vago, Jorge L.; Ma_MISS Team

2017-07-01

The Ma_MISS (Mars Multispectral Imager for Subsurface Studies) experiment is the visible and near infrared (VNIR) miniaturized spectrometer hosted by the drill system of the ExoMars 2020 rover. Ma_MISS will perform IR spectral reflectance investigations in the 0.4-2.2 μm range to characterize the mineralogy of excavated borehole walls at different depths (between 0 and 2 m). The spectral sampling is about 20 nm, whereas the spatial resolution over the target is 120 μm. Making use of the drill's movement, the instrument slit can scan a ring and build up hyperspectral images of a borehole. The main goal of the Ma_MISS instrument is to study the martian subsurface environment. Access to the martian subsurface is crucial to our ability to constrain the nature, timing, and duration of alteration and sedimentation processes on Mars, as well as habitability conditions. Subsurface deposits likely host and preserve H2O ice and hydrated materials that will contribute to our understanding of the H2O geochemical environment (both in the liquid and in the solid state) at the ExoMars 2020 landing site. The Ma_MISS spectral range and sampling capabilities have been carefully selected to allow the study of minerals and ices in situ before the collection of samples. Ma_MISS will be implemented to accomplish the following scientific objectives: (1) determine the composition of subsurface materials, (2) map the distribution of subsurface H2O and volatiles, (3) characterize important optical and physical properties of materials (e.g., grain size), and (4) produce a stratigraphic column that will inform with regard to subsurface geological processes. The Ma_MISS findings will help to refine essential criteria that will aid in our selection of the most interesting subsurface formations from which to collect samples.

Continual in situ monitoring of pore water stable isotopes in the subsurface

NASA Astrophysics Data System (ADS)

Volkmann, T. H. M.; Weiler, M.

2014-05-01

Stable isotope signatures provide an integral fingerprint of origin, flow paths, transport processes, and residence times of water in the environment. However, the full potential of stable isotopes to quantitatively characterize subsurface water dynamics is yet unfolded due to the difficulty in obtaining extensive, detailed, and repeated measurements of pore water in the unsaturated and saturated zone. This paper presents a functional and cost-efficient system for non-destructive continual in situ monitoring of pore water stable isotope signatures with high resolution. Automatic controllable valve arrays are used to continuously extract diluted water vapor in soil air via a branching network of small microporous probes into a commercial laser-based isotope analyzer. Normalized liquid-phase isotope signatures are then obtained based on a specific on-site calibration approach along with basic corrections for instrument bias and temperature dependent isotopic fractionation. The system was applied to sample depth profiles on three experimental plots with varied vegetation cover in southwest Germany. Two methods (i.e., based on advective versus diffusive vapor extraction) and two modes of sampling (i.e., using multiple permanently installed probes versus a single repeatedly inserted probe) were tested and compared. The results show that the isotope distribution along natural profiles could be resolved with sufficiently high accuracy and precision at sampling intervals of less than four minutes. The presented in situ approaches may thereby be used interchangeably with each other and with concurrent laboratory-based direct equilibration measurements of destructively collected samples. It is thus found that the introduced sampling techniques provide powerful tools towards a detailed quantitative understanding of dynamic and heterogeneous shallow subsurface and vadose zone processes.

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.

Dynamic coupling of subsurface and seepage flows solved within a regularized partition formulation

NASA Astrophysics Data System (ADS)

Marçais, J.; de Dreuzy, J.-R.; Erhel, J.

2017-11-01

Hillslope response to precipitations is characterized by sharp transitions from purely subsurface flow dynamics to simultaneous surface and subsurface flows. Locally, the transition between these two regimes is triggered by soil saturation. Here we develop an integrative approach to simultaneously solve the subsurface flow, locate the potential fully saturated areas and deduce the generated saturation excess overland flow. This approach combines the different dynamics and transitions in a single partition formulation using discontinuous functions. We propose to regularize the system of partial differential equations and to use classic spatial and temporal discretization schemes. We illustrate our methodology on the 1D hillslope storage Boussinesq equations (Troch et al., 2003). We first validate the numerical scheme on previous numerical experiments without saturation excess overland flow. Then we apply our model to a test case with dynamic transitions from purely subsurface flow dynamics to simultaneous surface and subsurface flows. Our results show that discretization respects mass balance both locally and globally, converges when the mesh or time step are refined. Moreover the regularization parameter can be taken small enough to ensure accuracy without suffering of numerical artefacts. Applied to some hundreds of realistic hillslope cases taken from Western side of France (Brittany), the developed method appears to be robust and efficient.

Groundwater assessment in Salboni Block, West Bengal (India) using remote sensing, geographical information system and multi-criteria decision analysis techniques

NASA Astrophysics Data System (ADS)

Jha, Madan K.; Chowdary, V. M.; Chowdhury, Alivia

2010-11-01

An approach is presented for the evaluation of groundwater potential using remote sensing, geographic information system, geoelectrical, and multi-criteria decision analysis techniques. The approach divides the available hydrologic and hydrogeologic data into two groups, exogenous (hydrologic) and endogenous (subsurface). A case study in Salboni Block, West Bengal (India), uses six thematic layers of exogenous parameters and four thematic layers of endogenous parameters. These thematic layers and their features were assigned suitable weights which were normalized by analytic hierarchy process and eigenvector techniques. The layers were then integrated using ArcGIS software to generate two groundwater potential maps. The hydrologic parameters-based groundwater potential zone map indicated that the `good' groundwater potential zone covers 27.14% of the area, the `moderate' zone 45.33%, and the `poor' zone 27.53%. A comparison of this map with the groundwater potential map based on subsurface parameters revealed that the hydrologic parameters-based map accurately delineates groundwater potential zones in about 59% of the area, and hence it is dependable to a certain extent. More than 80% of the study area has moderate-to-poor groundwater potential, which necessitates efficient groundwater management for long-term water security. Overall, the integrated technique is useful for the assessment of groundwater resources at a basin or sub-basin scale.

Innovative Methods for Integrating Knowledge for Long-Term Monitoring of Contaminated Groundwater Sites: Understanding Microorganism Communities and their Associated Hydrochemical Environment

NASA Astrophysics Data System (ADS)

Mouser, P. J.; Rizzo, D. M.; Druschel, G.; O'Grady, P.; Stevens, L.

2005-12-01

This interdisciplinary study integrates hydrochemical and genome-based data to estimate the redox processes occurring at long-term monitoring sites. Groundwater samples have been collected from a well-characterized landfill-leachate contaminated aquifer in northeastern New York. Primers from the 16S rDNA gene were used to amplify Bacteria and Archaea in groundwater taken from monitoring wells located in clean, fringe, and contaminated locations within the aquifer. PCR-amplified rDNA were digested with restriction enzymes to evaluate terminal restriction fragment length polymorphism (T-RFLP) community profiles. The rDNA was cloned, sequenced, and partial sequences were matched against known organisms using the NCBI Blast database. Phylogenetic trees and bootstrapping were used to identify classifications of organisms and compare the communities from clean, fringe, and contaminated locations. We used Artificial Neural Network (ANN) models to incorporate microbial data with hydrochemical information for improving our understanding of subsurface processes.

Delineation of karst terranes in complex environments: Application of modern developments in the wavelet theory and data mining

NASA Astrophysics Data System (ADS)

Alperovich, Leonid; Averbuch, Amir; Eppelbaum, Lev; Zheludev, Valery

2013-04-01

Karst areas occupy about 14% of the world land. Karst terranes of different origin have caused difficult conditions for building, industrial activity and tourism, and are the source of heightened danger for environment. Mapping of karst (sinkhole) hazards, obviously, will be one of the most significant problems of engineering geophysics in the XXI century. Taking into account the complexity of geological media, some unfavourable environments and known ambiguity of geophysical data analysis, a single geophysical method examination might be insufficient. Wavelet methodology as whole has a significant impact on cardinal problems of geophysical signal processing such as: denoising of signals, enhancement of signals and distinguishing of signals with closely related characteristics and integrated analysis of different geophysical fields (satellite, airborne, earth surface or underground observed data). We developed a three-phase approach to the integrated geophysical localization of subsurface karsts (the same approach could be used for following monitoring of karst dynamics). The first phase consists of modeling devoted to compute various geophysical effects characterizing karst phenomena. The second phase determines development of the signal processing approaches to analyzing of profile or areal geophysical observations. Finally, at the third phase provides integration of these methods in order to create a new method of the combined interpretation of different geophysical data. In the base of our combine geophysical analysis we put modern developments in the wavelet technique of the signal and image processing. The development of the integrated methodology of geophysical field examination will enable to recognizing the karst terranes even by a small ratio of "useful signal - noise" in complex geological environments. For analyzing the geophysical data, we used a technique based on the algorithm to characterize a geophysical image by a limited number of parameters. This set of parameters serves as a signature of the image and is to be utilized for discrimination of images containing karst cavity (K) from the images non-containing karst (N). The constructed algorithm consists of the following main phases: (a) collection of the database, (b) characterization of geophysical images, (c) and dimensionality reduction. Then, each image is characterized by the histogram of the coherency directions. As a result of the previous steps we obtain two sets K and N of the signatures vectors for images from sections containing karst cavity and non-karst subsurface, respectively.

Using an integrated approach between hydrological and crop models to assess surface water balance in ungauged basin

NASA Astrophysics Data System (ADS)

Negm, Amro; D'Agostino, Daniela; Lamaddalena, Nicola; Bacchi, Baldassare; Iacobellis, Vito

2013-04-01

In the last decades hydrological models have been extensively used in research fields in order to improve water balance assessment and to support integrated water resources management by quantifying the soil-plant-atmosphere interface. Due to complexity of the physical system, the mathematical models can generally represent and simulate only the basic components of the system. On the other hand, calibration and validation processes of the hydrological models in ungauged basins are still complex tasks, due to the lack of reliable methods and the uncertainty in representing the hydrological processes and the physical features of a basin. Therefore, in order to practically apply model's results, there is a continuous needing to assess their accuracy through the calibration and validation processes at gauged sites. In this context, an integrated approach is presented that couples a semi-distributed hydrological model called Distributed model for Runoff, Evapotranspiration, and Antecedent soil Moisture simulation (DREAM) with the FAO's Crop Water Productivity Simulation Model (AQUACROP). DREAM uses rainfall, Leaf Area Index (LAI) and potential evapotranspiration as inputs and streamflow, infiltration, real evapotranspiration, subsurface flow and deep percolation as outputs. Soil moisture content is accounted for as an internal variable. The simulations were done for Lama San Giorgio, a basin located in a wadi area in the central part of Apulia region (Southern Italy) for the period 2001-2005 and the meadow is mainly covered by durum wheat. According to ACLA2 project survey (Caliandro et al., 2005), the depth of the soil upper layers is about 80 cm. Calibration and validation of the DREAM model were carried out by assessing an accurate estimation of soil water content using AQUACROP model which is a more detailed model in terms of soil water dynamics. Instead, one of the most significant features of DREAM model is the evaluation of lateral flow exchanges by means of a redistribution function weighted by the wetness index. The calibration process was done by adjusting a specific parameter of the water balance, the subsurface flow (through a subsurface flow coefficient C), by exploiting the results of soil moisture content provided by AQUACROP model. Then, the outputs of daily soil water content obtained by DREAM model were compared with the estimations of soil behaviour provided by the AQUACROP model. The simulations were done for a certain number of cells in the study area, for different years. The chosen factors were used to obtain an average value of C in time and space, which in this study is equal to 0.5. Finally, the results of the DREAM model in terms of evapotranspiration provided a satisfactory approximation of those obtained by AQUACROP model, while the Canopy Cover, an output of AQUACROP, was compared with the LAI used as input for the DREAM model.

Elucidating Critical Zone Process Interactions with an Integrated Hydrology Model in a Headwaters Research Catchment

NASA Astrophysics Data System (ADS)

Collins, C.; Maxwell, R. M.

2017-12-01

Providence Creek (P300) watershed is an alpine headwaters catchment located at the Southern Sierra Critical Zone Observatory (SSCZO). Evidence of groundwater-dependent vegetation and drought-induced tree mortality at P300 along with the effect of subsurface characterization on mountain ecohydrology motivates this study. A hyper resolution integrated hydrology model of this site, along with extensive instrumentation, provides an opportunity to study the effects of lateral groundwater flow on vegetation's tolerance to drought. ParFlow-CLM is a fully integrated surface-subsurface model that is driven with reconstructed meteorology, such as the North American Land Data Assimilation System project phase 2 (NLDAS-2) dataset. However, large-scale data products mute orographic effects on climate at smaller scales. Climate variables often do not behave uniformly in highly heterogeneous mountain regions. Therefore, forcing physically-based integrated hydrologic models—especially of mountain headwaters catchments—with a large-scale data product is a major challenge. Obtaining reliable observations in complex terrain is challenging and while climate data products introduce uncertainties likewise, documented discrepancies between several data products and P300 observations suggest these data products may suffice. To tackle these issues, a suite of simulations was run to parse out (1) the effects of climate data source (data products versus observations) and (2) the effects of climate data spatial variability. One tool for evaluating the effect of climate data on model outputs is the relationship between latent head flux (LH) and evapotranspiration (ET) partitioning with water table depth (WTD). This zone of LH sensitivity to WTD is referred to as the "critical zone." Preliminary results suggest that these critical zone relationships are preserved despite forcing albeit significant shifts in magnitude. These results demonstrate that integrated hydrology models are sensitive to climate data thereby impacting the accuracy of hydrologic modeling of headwaters catchments used for water management and planning purposes and exploring the effects of climate change perturbations.

Storm hydrograph comparisons of subsurface pipe and stream channel discharge in a small, forested watershed in northern California

Treesearch

Jeffrey S. Albright

1992-01-01

The term piping has been used to describe subsurface erosion processes and concentrated subsurface water discharge. Physical features created by piping have been termed pipes. Piping can occur in natural landscapes due to individual or combined effects of mechanical (e.g., corrasion), chemical (e.g., soil dispersion), or biotic (e.g., animal burrowing) forces...

Evaluation of subsurface damage in concrete deck joints using impact echo method

DOE PAGES

Rickard, Larry; Choi, Wonchang

2016-01-01

Many factors can affect the overall performance and longevity of highway bridges, including the integrity of their deck joints. This study focuses on the evaluation of subsurface damage in deteriorated concrete deck joints, which includes the delamination and corrosion of the reinforcement. Impact echo and surface wave technology, mainly a portable seismic property analyzer (PSPA), were employed to evaluate the structural deficiency of concrete joints. Laboratory tests of core samples were conducted to verify the nondestructive test results. As a result, the primary advantage of the PSPA as a bridge assessment tool lies in its ability to assess the concrete’smore » modulus and to detect subsurface defects at a particular point simultaneously.« less

Geophysical framework of the southwestern Nevada volcanic field and hydrogeologic implications

USGS Publications Warehouse

Grauch, V.J.; Sawyer, David A.; Fridrich, Chris J.; Hudson, Mark R.

1999-01-01

Gravity and magnetic data, when integrated with other geophysical, geological, and rock-property data, provide a regional framework to view the subsurface geology in the southwestern Nevada volcanic field. The region has been loosely divided into six domains based on structural style and overall geophysical character. For each domain, the subsurface tectonic and magmatic features that have been inferred or interpreted from previous geophysical work has been reviewed. Where possible, abrupt changes in geophysical fields as evidence for potential structural lithologic control on ground-water flow has been noted. Inferred lithology is used to suggest associated hydrogeologic units in the subsurface. The resulting framework provides a basis for investigators to develop hypotheses from regional ground-water pathways where no drill-hole information exists.

Integration of P- and SH-wave high-resolution seismic reflection and micro-gravity techniques to improve interpretation of shallow subsurface structure: New Madrid seismic zone

USGS Publications Warehouse

Bexfield, C.E.; McBride, J.H.; Pugin, Andre J.M.; Ravat, D.; Biswas, S.; Nelson, W.J.; Larson, T.H.; Sargent, S.L.; Fillerup, M.A.; Tingey, B.E.; Wald, L.; Northcott, M.L.; South, J.V.; Okure, M.S.; Chandler, M.R.

2006-01-01

Shallow high-resolution seismic reflection surveys have traditionally been restricted to either compressional (P) or horizontally polarized shear (SH) waves in order to produce 2-D images of subsurface structure. The northernmost Mississippi embayment and coincident New Madrid seismic zone (NMSZ) provide an ideal laboratory to study the experimental use of integrating P- and SH-wave seismic profiles, integrated, where practicable, with micro-gravity data. In this area, the relation between "deeper" deformation of Paleozoic bedrock associated with the formation of the Reelfoot rift and NMSZ seismicity and "shallower" deformation of overlying sediments has remained elusive, but could be revealed using integrated P- and SH-wave reflection. Surface expressions of deformation are almost non-existent in this region, which makes seismic reflection surveying the only means of detecting structures that are possibly pertinent to seismic hazard assessment. Since P- and SH-waves respond differently to the rock and fluid properties and travel at dissimilar speeds, the resulting seismic profiles provide complementary views of the subsurface based on different levels of resolution and imaging capability. P-wave profiles acquired in southwestern Illinois and western Kentucky (USA) detect faulting of deep, Paleozoic bedrock and Cretaceous reflectors while coincident SH-wave surveys show that this deformation propagates higher into overlying Tertiary and Quaternary strata. Forward modeling of micro-gravity data acquired along one of the seismic profiles further supports an interpretation of faulting of bedrock and Cretaceous strata. The integration of the two seismic and the micro-gravity methods therefore increases the scope for investigating the relation between the older and younger deformation in an area of critical seismic hazard. ?? 2006 Elsevier B.V. All rights reserved.

Full Coupling Between the Atmosphere, Surface, and Subsurface for Integrated Hydrologic Simulation

NASA Astrophysics Data System (ADS)

Davison, Jason Hamilton; Hwang, Hyoun-Tae; Sudicky, Edward A.; Mallia, Derek V.; Lin, John C.

2018-01-01

An ever increasing community of earth system modelers is incorporating new physical processes into numerical models. This trend is facilitated by advancements in computational resources, improvements in simulation skill, and the desire to build numerical simulators that represent the water cycle with greater fidelity. In this quest to develop a state-of-the-art water cycle model, we coupled HydroGeoSphere (HGS), a 3-D control-volume finite element surface and variably saturated subsurface flow model that includes evapotranspiration processes, to the Weather Research and Forecasting (WRF) Model, a 3-D finite difference nonhydrostatic mesoscale atmospheric model. The two-way coupled model, referred to as HGS-WRF, exchanges the actual evapotranspiration fluxes and soil saturations calculated by HGS to WRF; conversely, the potential evapotranspiration and precipitation fluxes from WRF are passed to HGS. The flexible HGS-WRF coupling method allows for unique meshes used by each model, while maintaining mass and energy conservation between the domains. Furthermore, the HGS-WRF coupling implements a subtime stepping algorithm to minimize computational expense. As a demonstration of HGS-WRF's capabilities, we applied it to the California Basin and found a strong connection between the depth to the groundwater table and the latent heat fluxes across the land surface.

The Preliminary Results of GMSTech: A Software Development for Microseismic Characterization

NASA Astrophysics Data System (ADS)

Rohaman, Maman; Suhendi, Cahli; Verdhora Ry, Rexha; Sugiartono Prabowo, Billy; Widiyantoro, Sri; Nugraha, Andri Dian; Yudistira, Tedi; Mujihardi, Bambang

2017-04-01

The processing of microseismic data requires reliable software for imaging the condition of subsurface related to occurring microseismicity. In general, the currently available software is only specific for certain processing module and developed by the different developer. However, the software with integrated processing modules will give a better value because the users can use it easier and faster. We developed GMSTech (Ganesha Microseismic Technology), a C# language-based standing-alone software consisting several modules for processing of microseismic data. Its function is to solve a non-linear inverse problem and imaging the subsurface. C# library is supported by ILNumerics to reduce time consumption and give good visualization. In this preliminary result, we will present four developed modules: (1) hypocenter determination, (2) moment magnitude calculation, and (3) 3D seismic tomography. In the first module, we provide four methods for locating the microseismic events that can be chosen by a user independently: simulated annealing method, guided grid-search method, Geiger’s method, and joint hypocenter determination (JHD). The second module can be used for calculating moment magnitude using Brune method and to estimate the released energy of the event. At last, we also provided the module of 3-D seismic tomography for imaging the velocity structures based on delay time tomography. We demonstrated the software using both a synthetic data and a real data from a certain geothermal field in Indonesia. The results for all modules are reliable and remarkable, reviewed statistically by RMS error. We will keep examining the software using another set of data and developing further modules of processing.

Spatially adaptive migration tomography for multistatic GPR imaging

DOEpatents

Paglieroni, David W; Beer, N. Reginald

2013-08-13

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Zero source insertion technique to account for undersampling in GPR imaging

DOEpatents

Chambers, David H; Mast, Jeffrey E; Paglieroni, David W

2014-02-25

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Real-time system for imaging and object detection with a multistatic GPR array

DOEpatents

Paglieroni, David W; Beer, N Reginald; Bond, Steven W; Top, Philip L; Chambers, David H; Mast, Jeffrey E; Donetti, John G; Mason, Blake C; Jones, Steven M

2014-10-07

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Cryo-imaging of fluorescently labeled single cells in a mouse

NASA Astrophysics Data System (ADS)

Steyer, Grant J.; Roy, Debashish; Salvado, Olivier; Stone, Meredith E.; Wilson, David L.

2009-02-01

We developed a cryo-imaging system to provide single-cell detection of fluorescently labeled cells in mouse, with particular applicability to stem cells and metastatic cancer. The Case cryoimaging system consists of a fluorescence microscope, robotic imaging positioner, customized cryostat, PC-based control system, and visualization/analysis software. The system alternates between sectioning (10-40 μm) and imaging, collecting color brightfield and fluorescent blockface image volumes >60GB. In mouse experiments, we imaged quantum-dot labeled stem cells, GFP-labeled cancer and stem cells, and cell-size fluorescent microspheres. To remove subsurface fluorescence, we used a simplified model of light-tissue interaction whereby the next image was scaled, blurred, and subtracted from the current image. We estimated scaling and blurring parameters by minimizing entropy of subtracted images. Tissue specific attenuation parameters were found [uT : heart (267 +/- 47.6 μm), liver (218 +/- 27.1 μm), brain (161 +/- 27.4 μm)] to be within the range of estimates in the literature. "Next image" processing removed subsurface fluorescence equally well across multiple tissues (brain, kidney, liver, adipose tissue, etc.), and analysis of 200 microsphere images in the brain gave 97+/-2% reduction of subsurface fluorescence. Fluorescent signals were determined to arise from single cells based upon geometric and integrated intensity measurements. Next image processing greatly improved axial resolution, enabled high quality 3D volume renderings, and improved enumeration of single cells with connected component analysis by up to 24%. Analysis of image volumes identified metastatic cancer sites, found homing of stem cells to injury sites, and showed microsphere distribution correlated with blood flow patterns. We developed and evaluated cryo-imaging to provide single-cell detection of fluorescently labeled cells in mouse. Our cryo-imaging system provides extreme (>60GB), micron-scale, fluorescence, and bright field image data. Here we describe our image preprocessing, analysis, and visualization techniques. Processing improves axial resolution, reduces subsurface fluorescence by 97%, and enables single cell detection and counting. High quality 3D volume renderings enable us to evaluate cell distribution patterns. Applications include the myriad of biomedical experiments using fluorescent reporter gene and exogenous fluorophore labeling of cells in applications such as stem cell regenerative medicine, cancer, tissue engineering, etc.

SUBSURFACE VOLATIZATION AND VENTILATION SYSTEM (SVVS) - INNOVATIVE TECHNOLOGY REPORT

EPA Science Inventory

This report summarizes the findings associated with a Demonstration Test of Environmental Improvement Technologies’ (EIT) Subsurface Volatilization and Ventilation System (SVVS) process. The technology was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) ...

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

Brandenburg 3D - a comprehensive 3D Subsurface Model, Conception of an Infrastructure Node and a Web Application

NASA Astrophysics Data System (ADS)

Kerschke, Dorit; Schilling, Maik; Simon, Andreas; Wächter, Joachim

2014-05-01

The Energiewende and the increasing scarcity of raw materials will lead to an intensified utilization of the subsurface in Germany. Within this context, geological 3D modeling is a fundamental approach for integrated decision and planning processes. Initiated by the development of the European Geospatial Infrastructure INSPIRE, the German State Geological Offices started digitizing their predominantly analog archive inventory. Until now, a comprehensive 3D subsurface model of Brandenburg did not exist. Therefore the project B3D strived to develop a new 3D model as well as a subsequent infrastructure node to integrate all geological and spatial data within the Geodaten-Infrastruktur Brandenburg (Geospatial Infrastructure, GDI-BB) and provide it to the public through an interactive 2D/3D web application. The functionality of the web application is based on a client-server architecture. Server-sided, all available spatial data is published through GeoServer. GeoServer is designed for interoperability and acts as the reference implementation of the Open Geospatial Consortium (OGC) Web Feature Service (WFS) standard that provides the interface that allows requests for geographical features. In addition, GeoServer implements, among others, the high performance certified compliant Web Map Service (WMS) that serves geo-referenced map images. For publishing 3D data, the OGC Web 3D Service (W3DS), a portrayal service for three-dimensional geo-data, is used. The W3DS displays elements representing the geometry, appearance, and behavior of geographic objects. On the client side, the web application is solely based on Free and Open Source Software and leans on the JavaScript API WebGL that allows the interactive rendering of 2D and 3D graphics by means of GPU accelerated usage of physics and image processing as part of the web page canvas without the use of plug-ins. WebGL is supported by most web browsers (e.g., Google Chrome, Mozilla Firefox, Safari, and Opera). The web application enables an intuitive navigation through all available information and allows the visualization of geological maps (2D), seismic transects (2D/3D), wells (2D/3D), and the 3D-model. These achievements will alleviate spatial and geological data management within the German State Geological Offices and foster the interoperability of heterogeneous systems. It will provide guidance to a systematic subsurface management across system, domain and administrative boundaries on the basis of a federated spatial data infrastructure, and include the public in the decision processes (e-Governance). Yet, the interoperability of the systems has to be strongly propelled forward through agreements on standards that need to be decided upon in responsible committees. The project B3D is funded with resources from the European Fund for Regional Development (EFRE).

Surface Modification and Surface - Subsurface Exchange Processes on Europa

NASA Astrophysics Data System (ADS)

Phillips, Cynthia B.; Molaro, Jamie; Hand, Kevin P.

2017-10-01

The surface of Jupiter’s moon Europa is modified by exogenic processes such as sputtering, gardening, radiolysis, sulfur ion implantation, and thermal processing, as well as endogenic processes including tidal shaking, mass wasting, and the effects of subsurface tectonic and perhaps cryovolcanic activity. New materials are created or deposited on the surface (radiolysis, micrometeorite impacts, sulfur ion implantation, cryovolcanic plume deposits), modified in place (thermal segregation, sintering), transported either vertically or horizontally (sputtering, gardening, mass wasting, tectonic and cryovolcanic activity), or lost from Europa completely (sputtering, plumes, larger impacts). Some of these processes vary spatially, as visible in Europa’s leading-trailing hemisphere brightness asymmetry.Endogenic geologic processes also vary spatially, depending on terrain type. The surface can be classified into general landform categories that include tectonic features (ridges, bands, cracks); disrupted “chaos-type” terrain (chaos blocks, matrix, domes, pits, spots); and impact craters (simple, complex, multi-ring). The spatial distribution of these terrain types is relatively random, with some differences in apex-antiapex cratering rates and latitudinal variation in chaos vs. tectonic features.In this work, we extrapolate surface processes and rates from the top meter of the surface in conjunction with global estimates of transport and resurfacing rates. We combine near-surface modification with an estimate of surface-subsurface (and vice versa) transport rates for various geologic terrains based on an average of proposed formation mechanisms, and a spatial distribution of each landform type over Europa’s surface area.Understanding the rates and mass balance for each of these processes, as well as their spatial and temporal variability, allows us to estimate surface - subsurface exchange rates over the average surface age (~50myr) of Europa. Quantifying the timescale and volume of transported material will yield insight on whether such a process may provide fuel to sustain a biosphere in Europa’s subsurface ocean, which is relevant to searches for life by a future mission such as a potential Europa Lander.

Surface Modification and Surface - Subsurface Exchange Processes on Europa

NASA Astrophysics Data System (ADS)

Phillips, C. B.; Molaro, J.; Hand, K. P.

2017-12-01

The surface of Jupiter's moon Europa is modified by exogenic processes such as sputtering, gardening, radiolysis, sulfur ion implantation, and thermal processing, as well as endogenic processes including tidal shaking, mass wasting, and the effects of subsurface tectonic and perhaps cryovolcanic activity. New materials are created or deposited on the surface (radiolysis, micrometeorite impacts, sulfur ion implantation, cryovolcanic plume deposits), modified in place (thermal segregation, sintering), transported either vertically or horizontally (sputtering, gardening, mass wasting, tectonic and cryovolcanic activity), or lost from Europa completely (sputtering, plumes, larger impacts). Some of these processes vary spatially, as visible in Europa's leading-trailing hemisphere brightness asymmetry. Endogenic geologic processes also vary spatially, depending on terrain type. The surface can be classified into general landform categories that include tectonic features (ridges, bands, cracks); disrupted "chaos-type" terrain (chaos blocks, matrix, domes, pits, spots); and impact craters (simple, complex, multi-ring). The spatial distribution of these terrain types is relatively random, with some differences in apex-antiapex cratering rates and latitudinal variation in chaos vs. tectonic features. In this work, we extrapolate surface processes and rates from the top meter of the surface in conjunction with global estimates of transport and resurfacing rates. We combine near-surface modification with an estimate of surface-subsurface (and vice versa) transport rates for various geologic terrains based on an average of proposed formation mechanisms, and a spatial distribution of each landform type over Europa's surface area. Understanding the rates and mass balance for each of these processes, as well as their spatial and temporal variability, allows us to estimate surface - subsurface exchange rates over the average surface age ( 50myr) of Europa. Quantifying the timescale and volume of transported material will yield insight on whether such a process may provide fuel to sustain a biosphere in Europa's subsurface ocean, which is relevant to searches for life by a future mission such as a potential Europa Lander.

Towards a high resolution, integrated hydrology model of North America.

NASA Astrophysics Data System (ADS)

Maxwell, R. M.; Condon, L. E.

2015-12-01

Recent studies demonstrate feedbacks between groundwater dynamics, overland flow, land surface and vegetation processes, and atmospheric boundary layer development that significantly affect local and regional climate across a range of climatic conditions. Furthermore, the type and distribution of vegetation cover alters land-atmosphere water and energy fluxes, as well as runoff generation and overland flow processes. These interactions can result in significant feedbacks on local and regional climate. In mountainous regions, recent research has shown that spatial and temporal variability in annual evapotranspiration, and thus water budgets, is strongly dependent on lateral groundwater flow; however, the full effects of these feedbacks across varied terrain (e.g. from plains to mountains) are not well understood. Here, we present a high-resolution, integrated hydrology model that covers much of continental North America and encompasses the Mississippi and Colorado watersheds. The model is run in a fully-transient manner at hourly temporal resolution incorporating fully-coupled land energy states and fluxes with integrated surface and subsurface hydrology. Connections are seen between hydrologic variables (such as water table depth) and land energy fluxes (such as latent heat) and spatial and temporal scaling is shown to span many orders of magnitude. Using these transient simulations as a proof of concept, we present a vision for future integrated simulation capabilities.

Designing sustainable and economically attractive brownfield revitalization options using an integrated assessment model.

PubMed

Schädler, S; Morio, M; Bartke, S; Rohr-Zänker, R; Finkel, M

2011-03-01

We describe the development of an integrated assessment model which evaluates redevelopment options of large contaminated brownfields and we present the application of the model in a case study. Aiming to support efficient and sustainable revitalization and communication between stakeholders, the presented assessment model integrates three pinnacles of brownfield revitalization: (i) subsurface remediation and site preparation costs, (ii) market-oriented economic appraisal, and (iii) the expected contribution of planned future land use to sustainable community and regional development. For the assessment, focus is set on the early stage of the brownfield redevelopment process, which is characterized by limited data availability and by flexibility in land use planning and development scope. At this stage, revealing the consequences of adjustments and alterations in planning options can foster efficiency in communication between the involved parties and thereby facilitates the brownfield revitalization process. Results from the case-study application indicate that the integrated assessment provides help in the identification of land use options beneficial in both a sustainable and an economical sense. For the study site it is shown on one hand that brownfield redevelopment is not automatically in line with sustainable regional development, and on the other hand it is demonstrated that additional contributions to sustainability are not intrinsically tied to increased costs. Copyright © 2010 Elsevier Ltd. All rights reserved.

Development and application of a hillslope hydrologic model

USGS Publications Warehouse

Blain, C.A.; Milly, P.C.D.

1991-01-01

A vertically integrated two-dimensional lateral flow model of soil moisture has been developed. Derivation of the governing equation is based on a physical interpretation of hillslope processes. The lateral subsurface-flow model permits variability of precipitation and evapotranspiration, and allows arbitrary specification of soil-moisture retention properties. Variable slope, soil thickness, and saturation are all accommodated. The numerical solution method, a Crank-Nicolson, finite-difference, upstream-weighted scheme, is simple and robust. A small catchment in northeastern Kansas is the subject of an application of the lateral subsurface-flow model. Calibration of the model using observed discharge provides estimates of the active porosity (0.1 cm3/cm3) and of the saturated horizontal hydraulic conductivity (40 cm/hr). The latter figure is at least an order of magnitude greater than the vertical hydraulic conductivity associated with the silty clay loam soil matrix. The large value of hydraulic conductivity derived from the calibration is suggestive of macropore-dominated hillslope drainage. The corresponding value of active porosity agrees well with a published average value of the difference between total porosity and field capacity for a silty clay loam. ?? 1991.

Double barrier system for an in situ conversion process

DOEpatents

McKinzie, Billy John [Houston, TX; Vinegar, Harold J [Bellaire, TX; Cowan, Kenneth Michael [Sugar land, TX; Deeg, Wolfgang Friedrich Johann [Houston, TX; Wong, Sau-Wai [Rijswijk, NL

2009-05-05

A barrier system for a subsurface treatment area is described. The barrier system includes a first barrier formed around at least a portion of the subsurface treatment area. The first barrier is configured to inhibit fluid from exiting or entering the subsurface treatment area. A second barrier is formed around at least a portion of the first barrier. A separation space exists between the first barrier and the second barrier.

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.

Diffusion and aggregation of subsurface radiation defects in lithium fluoride nanocrystals

NASA Astrophysics Data System (ADS)

Voitovich, A. P.; Kalinov, V. S.; Martynovich, E. F.; Stupak, A. P.; Runets, L. P.

2015-09-01

Lithium fluoride nanocrystals were irradiated by gamma rays at a temperature below the temperature corresponding to the mobility of anion vacancies. The kinetics of the aggregation of radiation-induced defects in subsurface layers of nanocrystals during annealing after irradiation was elucidated. The processes that could be used to determine the activation energy of the diffusion of anion vacancies were revealed. The value of this energy in subsurface layers was obtained. For subsurface layers, the concentrations ratio of vacancies and defects consisting of one vacancy and two electrons was found. The factors responsible for the differences in the values of the activation energies and concentration ratios in subsurface layers and in the bulk of the crystals were discussed.

Biogeochemistry: Hexadecane decay by methanogenesis

USGS Publications Warehouse

Anderson, Robert T.; Lovely, Derek R.

2000-01-01

The potential for the biological conversion of long-chain saturated hydrocarbons to methane under anaerobic conditions has been demonstrated by using an enrichment culture of bacteria to degrade pure-phase hexadecane1. The formation of methane in hydrocarbon-rich subsurface zones could be explained if a similar conversion of long-chain alkanes to methane were to take place in subsurface environments. If this process could be stimulated in the subsurface, it could be used to enhance hydrocarbon recovery from petroleum reserves1, 2. Parkes2, however, questions the environmental significance of the enrichment-culture results1 on the grounds that alkane conversion to methane is very slow and because sulphate-reducing and methanogenic bacteria might both be necessary for even this slow process to occur, restricting the conversion to specialized, unusual zones in sediments. Here we show that, on the contrary, subsurface bacteria can adapt to convert hexadecane to methane rapidly and in the absence of sulphate-reducing bacteria.

Remote sensing capacity of Raman spectroscopy in identification of mineral and organic constituents

NASA Astrophysics Data System (ADS)

Chen, Bin; Stoker, Carol; Cabrol, Nathalie; McKay, Christopher P.

2007-09-01

We present design, integration and test results for a field Raman spectrometer science payload, integrated into the Mars Analog Research and Technology (MARTE) drilling platform. During the drilling operation, the subsurface Raman spectroscopy inspection system has obtained signatures of organic and mineral compositions. We also performed ground truth studies using both this field unit and a laboratory micro Raman spectrometer equipped with multiple laser excitation wavelengths on series of field samples including Mojave rocks, Laguna Verde salty sediment and Rio Tinto topsoil. We have evaluated laser excitation conditions and optical probe designs for further improvement. We have demonstrated promising potential for Raman spectroscopy as a non-destructive in situ, high throughput, subsurface detection technique, as well as a desirable active remote sensing tool for future planetary and space missions.

Accelerating Subsurface Transport Simulation on Heterogeneous Clusters

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

Villa, Oreste; Gawande, Nitin A.; Tumeo, Antonino

Reactive transport numerical models simulate chemical and microbiological reactions that occur along a flowpath. These models have to compute reactions for a large number of locations. They solve the set of ordinary differential equations (ODEs) that describes the reaction for each location through the Newton-Raphson technique. This technique involves computing a Jacobian matrix and a residual vector for each set of equation, and then solving iteratively the linearized system by performing Gaussian Elimination and LU decomposition until convergence. STOMP, a well known subsurface flow simulation tool, employs matrices with sizes in the order of 100x100 elements and, for numerical accuracy,more » LU factorization with full pivoting instead of the faster partial pivoting. Modern high performance computing systems are heterogeneous machines whose nodes integrate both CPUs and GPUs, exposing unprecedented amounts of parallelism. To exploit all their computational power, applications must use both the types of processing elements. For the case of subsurface flow simulation, this mainly requires implementing efficient batched LU-based solvers and identifying efficient solutions for enabling load balancing among the different processors of the system. In this paper we discuss two approaches that allows scaling STOMP's performance on heterogeneous clusters. We initially identify the challenges in implementing batched LU-based solvers for small matrices on GPUs, and propose an implementation that fulfills STOMP's requirements. We compare this implementation to other existing solutions. Then, we combine the batched GPU solver with an OpenMP-based CPU solver, and present an adaptive load balancer that dynamically distributes the linear systems to solve between the two components inside a node. We show how these approaches, integrated into the full application, provide speed ups from 6 to 7 times on large problems, executed on up to 16 nodes of a cluster with two AMD Opteron 6272 and a Tesla M2090 per node.« less

Using lagged dependence to identify (de)coupled surface and subsurface soil moisture values

NASA Astrophysics Data System (ADS)

Carranza, Coleen D. U.; van der Ploeg, Martine J.; Torfs, Paul J. J. F.

2018-04-01

Recent advances in radar remote sensing popularized the mapping of surface soil moisture at different spatial scales. Surface soil moisture measurements are used in combination with hydrological models to determine subsurface soil moisture values. However, variability of soil moisture across the soil column is important for estimating depth-integrated values, as decoupling between surface and subsurface can occur. In this study, we employ new methods to investigate the occurrence of (de)coupling between surface and subsurface soil moisture. Using time series datasets, lagged dependence was incorporated in assessing (de)coupling with the idea that surface soil moisture conditions will be reflected at the subsurface after a certain delay. The main approach involves the application of a distributed-lag nonlinear model (DLNM) to simultaneously represent both the functional relation and the lag structure in the time series. The results of an exploratory analysis using residuals from a fitted loess function serve as a posteriori information to determine (de)coupled values. Both methods allow for a range of (de)coupled soil moisture values to be quantified. Results provide new insights into the decoupled range as its occurrence among the sites investigated is not limited to dry conditions.

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.

Exploring Subsurface Geology Using Radar Techniques: Experiments in Sahara and Consequences for Mars Exploration

NASA Astrophysics Data System (ADS)

Paillou, P.; Grandjean, G.; Heggy, E.; Farr, T.

2004-05-01

For several years, we have conducted a quantitative study of radar penetration performances in various desert arid environments. This study combines both SAR (Synthetic Aperture Radar) imaging from orbital and airborne platforms and in situ GPR (Ground Penetrating Radar) measurements. Laboratory characterization of various minerals and rocks are used as input to electromagnetic models such as IEM (Integral Equation Model) and FDTD (Finite Difference Time Domain) that describe the subsurface scattering process for inversion purposes. Several test sites were explored, mainly the Sahara. Our first experiment was realized in Republic of Djibouti, an arid volcanic area which is a good analog to Mars. We observed a very little radar penetration there because of the presence of iron oxides and salts in the subsurface that make the soil conductive [Paillou et al., GRL, 2001]. A more favorable site for radar penetration was then explored in southern Egypt: the Bir Safsaf area where buried river channels were discovered using orbital SAR images. We showed how to combine SAR and GPR in order to obtain a complete description of subsurface geology down to several meters [Paillou et al., IEEE TGRS, 2003]. Such field experiments were the basis for more systematic laboratory measurements of the electromagnetic properties of various rocks and minerals which were used in numerical models in order to simulate the performances of future Martian radars, e.g. MARSIS and NETLANDER low frequency radars [Heggy et al., Icarus, 2001; Berthelier et al., JGR, 2003; Heggy et al., JGR, 2003]. More recently, new explorations were conducted in Mauritania in order to demonstrate radar capacities for geologic mapping [Grandjean et al., Coll. Afr. Geol., 2004] and in Libya where radar discovered a double impact crater in the southern desert [Paillou et al., C.R. Geoscience, 2003]. More local radar experiments were also conducted on a test site located in France, the Pyla sand dune, where we observed and modeled a radar signature of subsurface water [Grandjean et al., IEEE TGRS, 2001; Paillou et al., IGARSS'03, 2003]. All of these results shall be used in the context of "terrestrial analogs to Mars" studies in order to prepare for future Mars exploration using radars [Farr et al., Planet. Dec. Study, 2002; Paillou et al., 35th LPSC, 2004]: it concerns both GPR instruments onboard rovers and landers devoted to the exploration of the deep subsurface [Berthelier at al., ESA Pasteur, 2003] and SAR imaging systems onboard orbital platforms for global mapping of the shallow subsurface geology [Paillou et al., Conf. Water Mars, 2001].

Estimating and mapping ecological processes influencing microbial community assembly

PubMed Central

Stegen, James C.; Lin, Xueju; Fredrickson, Jim K.; Konopka, Allan E.

2015-01-01

Ecological community assembly is governed by a combination of (i) selection resulting from among-taxa differences in performance; (ii) dispersal resulting from organismal movement; and (iii) ecological drift resulting from stochastic changes in population sizes. The relative importance and nature of these processes can vary across environments. Selection can be homogeneous or variable, and while dispersal is a rate, we conceptualize extreme dispersal rates as two categories; dispersal limitation results from limited exchange of organisms among communities, and homogenizing dispersal results from high levels of organism exchange. To estimate the influence and spatial variation of each process we extend a recently developed statistical framework, use a simulation model to evaluate the accuracy of the extended framework, and use the framework to examine subsurface microbial communities over two geologic formations. For each subsurface community we estimate the degree to which it is influenced by homogeneous selection, variable selection, dispersal limitation, and homogenizing dispersal. Our analyses revealed that the relative influences of these ecological processes vary substantially across communities even within a geologic formation. We further identify environmental and spatial features associated with each ecological process, which allowed mapping of spatial variation in ecological-process-influences. The resulting maps provide a new lens through which ecological systems can be understood; in the subsurface system investigated here they revealed that the influence of variable selection was associated with the rate at which redox conditions change with subsurface depth. PMID:25983725

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.

Integrated geophysical methods for geotechnical subsurface investigations : final report.

DOT National Transportation Integrated Search

2006-01-01

This report summarizes the New Hampshire Department of Transportations (NHDOTs) investigation of : geophysical techniques to supplement conventional test borings and other explorations on transportation projects. : The Departments geotechnic...

Time-lapse seismic waveform modelling and attribute analysis using hydromechanical models for a deep reservoir undergoing depletion

NASA Astrophysics Data System (ADS)

He, Y.-X.; Angus, D. A.; Blanchard, T. D.; Wang, G.-L.; Yuan, S.-Y.; Garcia, A.

2016-04-01

Extraction of fluids from subsurface reservoirs induces changes in pore pressure, leading not only to geomechanical changes, but also perturbations in seismic velocities and hence observable seismic attributes. Time-lapse seismic analysis can be used to estimate changes in subsurface hydromechanical properties and thus act as a monitoring tool for geological reservoirs. The ability to observe and quantify changes in fluid, stress and strain using seismic techniques has important implications for monitoring risk not only for petroleum applications but also for geological storage of CO2 and nuclear waste scenarios. In this paper, we integrate hydromechanical simulation results with rock physics models and full-waveform seismic modelling to assess time-lapse seismic attribute resolution for dynamic reservoir characterization and hydromechanical model calibration. The time-lapse seismic simulations use a dynamic elastic reservoir model based on a North Sea deep reservoir undergoing large pressure changes. The time-lapse seismic traveltime shifts and time strains calculated from the modelled and processed synthetic data sets (i.e. pre-stack and post-stack data) are in a reasonable agreement with the true earth models, indicating the feasibility of using 1-D strain rock physics transform and time-lapse seismic processing methodology. Estimated vertical traveltime shifts for the overburden and the majority of the reservoir are within ±1 ms of the true earth model values, indicating that the time-lapse technique is sufficiently accurate for predicting overburden velocity changes and hence geomechanical effects. Characterization of deeper structure below the overburden becomes less accurate, where more advanced time-lapse seismic processing and migration is needed to handle the complex geometry and strong lateral induced velocity changes. Nevertheless, both migrated full-offset pre-stack and near-offset post-stack data image the general features of both the overburden and reservoir units. More importantly, the results from this study indicate that integrated seismic and hydromechanical modelling can help constrain time-lapse uncertainty and hence reduce risk due to fluid extraction and injection.

Effects of Subsurface Sampling & Processing on Martian Simulant Containing Varying Quantities of Water

NASA Technical Reports Server (NTRS)

Menard, J.; Sangillo, J.; Savain, A.; McNamara, K. M.

2004-01-01

The presence of water-ice in the Martian subsurface is a subject of much debate and excited speculation. Recent results from the gammaray spectrometer (GRS) on board NASA's Mars Odyssey spacecraft indicate the presence of large amounts of hydrogen in regions of predicted ice stability. The combination of chemistry, low gravitational field (3.71 m/s(exp 2)) and a surface pressure of about 6.36 mbar at the mean radius, place limits on the stability of H2O on the surface, however, results from the GRS indicate that the hydrogen rich phase may be present at a depth as shallow as one meter in some locations on Mars. The potential for water on Mars leads directly to the speculation that life may once have existed there, since liquid water is the unifying factor for environments known to support life on Earth. Lubricant-free drilling has been considered as a means of obtaining water-rich subsurface samples on Mars, and two recent white papers sponsored by the Mars Program have attempted to identify the problems associated with this goal. The two major issues identified were: the engineering challenges of drilling into a water-soil mixture where phase changes may occur; and the potential to compromise the integrity of in-situ scientific analysis due to contamination, volatilization, and mineralogical or chemical changes as a result of processing. This study is a first attempt to simulate lubricantfree drilling into JSC Mars-1 simulant containing up to 50% water by weight. The goal is to address the following: 1) Does sample processing cause reactions or changes in mineralogy which will compromise the interpretation of scientific measurements conducted on the surface? 2) Does the presence of water-ice in the sample complicate (1)? 3) Do lubricant-free drilling and processing leave trace contaminants which may compromise our understanding of sample composition? 4) How does the torque/power required for drilling change as a function of water content and does this lead to unexpected thermal effects?

Vertically-integrated Approaches for Carbon Sequestration Modeling

NASA Astrophysics Data System (ADS)

Bandilla, K.; Celia, M. A.; Guo, B.

2015-12-01

Carbon capture and sequestration (CCS) is being considered as an approach to mitigate anthropogenic CO2 emissions from large stationary sources such as coal fired power plants and natural gas processing plants. Computer modeling is an essential tool for site design and operational planning as it allows prediction of the pressure response as well as the migration of both CO2 and brine in the subsurface. Many processes, such as buoyancy, hysteresis, geomechanics and geochemistry, can have important impacts on the system. While all of the processes can be taken into account simultaneously, the resulting models are computationally very expensive and require large numbers of parameters which are often uncertain or unknown. In many cases of practical interest, the computational and data requirements can be reduced by choosing a smaller domain and/or by neglecting or simplifying certain processes. This leads to a series of models with different complexity, ranging from coupled multi-physics, multi-phase three-dimensional models to semi-analytical single-phase models. Under certain conditions the three-dimensional equations can be integrated in the vertical direction, leading to a suite of two-dimensional multi-phase models, termed vertically-integrated models. These models are either solved numerically or simplified further (e.g., assumption of vertical equilibrium) to allow analytical or semi-analytical solutions. This presentation focuses on how different vertically-integrated models have been applied to the simulation of CO2 and brine migration during CCS projects. Several example sites, such as the Illinois Basin and the Wabamun Lake region of the Alberta Basin, are discussed to show how vertically-integrated models can be used to gain understanding of CCS operations.

Analysis of Surface Heterogeneity Effects with Mesoscale Terrestrial Modeling Platforms

NASA Astrophysics Data System (ADS)

Simmer, C.

2015-12-01

An improved understanding of the full variability in the weather and climate system is crucial for reducing the uncertainty in weather forecasting and climate prediction, and to aid policy makers to develop adaptation and mitigation strategies. A yet unknown part of uncertainty in the predictions from the numerical models is caused by the negligence of non-resolved land surface heterogeneity and the sub-surface dynamics and their potential impact on the state of the atmosphere. At the same time, mesoscale numerical models using finer horizontal grid resolution [O(1)km] can suffer from inconsistencies and neglected scale-dependencies in ABL parameterizations and non-resolved effects of integrated surface-subsurface lateral flow at this scale. Our present knowledge suggests large-eddy-simulation (LES) as an eventual solution to overcome the inadequacy of the physical parameterizations in the atmosphere in this transition scale, yet we are constrained by the computational resources, memory management, big-data, when using LES for regional domains. For the present, there is a need for scale-aware parameterizations not only in the atmosphere but also in the land surface and subsurface model components. In this study, we use the recently developed Terrestrial Systems Modeling Platform (TerrSysMP) as a numerical tool to analyze the uncertainty in the simulation of surface exchange fluxes and boundary layer circulations at grid resolutions of the order of 1km, and explore the sensitivity of the atmospheric boundary layer evolution and convective rainfall processes on land surface heterogeneity.

LLNL SFA OBER SBR FY17 Program Management and Performance Report: Subsurface Biogeochemistry of Actinides

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

Kersting, Annie B.

A major scientific challenge in environmental sciences is to identify the dominant processes controlling actinide transport in the environment. It is estimated that currently, over 2200 metric tons of anthropogenic plutonium (Pu) has accumulated worldwide, a number that increases yearly with additional spent nuclear fuel (Ewing et al., 2010). Plutonium has been shown to migrate on the scale of kilometers, giving way to a critical concern that the fundamental biogeochemical processes that control its behavior in the subsurface are not well understood (Kersting et al. 1999; Novikov et al. 2006; Santschi et al. 2002). Neptunium (Np) is less prevalent inmore » the environment; however, it is predicted to be a significant long-term dose contributor in high-level nuclear waste. Our focus on Np chemistry in this Science Plan is intended to help formulate a better understanding of Pu redox transformations in the environment and clarify the differences between the two long-lived actinides. The research approach of our Science Plan combines (1) Fundamental Mechanistic Studies that identify and quantify biogeochemical processes that control actinide behavior in solution and on solids, (2) Field Integration Studies that investigate the transport characteristics of Pu and test our conceptual understanding of actinide transport, and (3) Actinide Research Capabilities that allow us to achieve the objectives of this Scientific Focus Area (SFA) and provide new opportunities for advancing actinide environmental chemistry. These three Research Thrusts form the basis of our SFA Science Program.« less

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

Kersting, Annie B.; Zavarin, Mavrik

A major scientific challenge in environmental sciences is to identify the dominant processes controlling actinide transport in the environment. It is estimated that currently, over 2200 metric tons of plutonium (Pu) have been deposited in the subsurface worldwide, a number that increases yearly with additional spent nuclear fuel (Ewing et al., 2010). Plutonium has been shown to migrate on the scale of kilometers, giving way to a critical concern that the fundamental biogeochemical processes that control its behavior in the subsurface are not well understood (Kersting et al., 1999; Novikov et al., 2006; Santschi et al., 2002). Neptunium (Np) ismore » less prevalent in the environment; however, it is predicted to be a significant long-term dose contributor in high-level nuclear waste. Our focus on Np chemistry in this Science Plan is intended to help formulate a better understanding of Pu redox transformations in the environment and clarify the differences between the two long-lived actinides. The research approach of our Science Plan combines (1) Fundamental Mechanistic Studies that identify and quantify biogeochemical processes that control actinide behavior in solution and on solids, (2) Field Integration Studies that investigate the transport characteristics of Pu and test our conceptual understanding of actinide transport, and (3) Actinide Research Capabilities that allow us to achieve the objectives of this Scientific Focus Area (SFA and provide new opportunities for advancing actinide environmental chemistry. These three Research Thrusts form the basis of our SFA Science Program (Figure 1).« less

M4FT-16LL080302052-Update to Thermodynamic Database Development and Sorption Database Integration

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

Zavarin, Mavrik; Wolery, T. J.; Atkins-Duffin, C.

2016-08-16

This progress report (Level 4 Milestone Number M4FT-16LL080302052) summarizes research conducted at Lawrence Livermore National Laboratory (LLNL) within the Argillite Disposal R&D Work Package Number FT-16LL08030205. The focus of this research is the thermodynamic modeling of Engineered Barrier System (EBS) materials and properties and development of thermodynamic databases and models to evaluate the stability of EBS materials and their interactions with fluids at various physico-chemical conditions relevant to subsurface repository environments. The development and implementation of equilibrium thermodynamic models are intended to describe chemical and physical processes such as solubility, sorption, and diffusion.

Application of experimental design in geothermal resources assessment of Ciwidey-Patuha, West Java, Indonesia

NASA Astrophysics Data System (ADS)

Ashat, Ali; Pratama, Heru Berian

2017-12-01

The successful Ciwidey-Patuha geothermal field size assessment required integration data analysis of all aspects to determined optimum capacity to be installed. Resources assessment involve significant uncertainty of subsurface information and multiple development scenarios from these field. Therefore, this paper applied the application of experimental design approach to the geothermal numerical simulation of Ciwidey-Patuha to generate probabilistic resource assessment result. This process assesses the impact of evaluated parameters affecting resources and interacting between these parameters. This methodology have been successfully estimated the maximum resources with polynomial function covering the entire range of possible values of important reservoir parameters.

In situ mitigation of subsurface and peripheral focused ion beam damage via simultaneous pulsed laser heating

DOE PAGES

Stanford, Michael G.; Lewis, Brett B.; Iberi, Vighter O.; ...

2016-02-16

Focused helium and neon ion (He(+)/Ne(+) ) beam processing has recently been used to push resolution limits of direct-write nanoscale synthesis. The ubiquitous insertion of focused He(+) /Ne(+) beams as the next-generation nanofabrication tool-of-choice is currently limited by deleterious subsurface and peripheral damage induced by the energetic ions in the underlying substrate. The in situ mitigation of subsurface damage induced by He(+)/Ne(+) ion exposures in silicon via a synchronized infrared pulsed laser-assisted process is demonstrated. The pulsed laser assist provides highly localized in situ photothermal energy which reduces the implantation and defect concentration by greater than 90%. The laser-assisted exposuremore » process is also shown to reduce peripheral defects in He(+) patterned graphene, which makes this process an attractive candidate for direct-write patterning of 2D materials. In conclusion, these results offer a necessary solution for the applicability of high-resolution direct-write nanoscale material processing via focused ion beams.« less

Methanogenic degradation of petroleum hydrocarbons in subsurface environments remediation, heavy oil formation, and energy recovery.

PubMed

Gray, N D; Sherry, A; Hubert, C; Dolfing, J; Head, I M

2010-01-01

Hydrocarbons are common constituents of surface, shallow, and deep-subsurface environments. Under anaerobic conditions, hydrocarbons can be degraded to methane by methanogenic microbial consortia. This degradation process is widespread in the geosphere. In comparison with other anaerobic processes, methanogenic hydrocarbon degradation is more sustainable over geological time scales because replenishment of an exogenous electron acceptor is not required. As a consequence, this process has been responsible for the formation of the world's vast deposits of heavy oil, which far exceed conventional oil assets such as those found in the Middle East. Methanogenic degradation is also a potentially important component of attenuation in hydrocarbon contamination plumes. Studies of the organisms, syntrophic partnerships, mechanisms, and geochemical signatures associated with methanogenic hydrocarbon degradation have identified common themes and diagnostic markers for this process in the subsurface. These studies have also identified the potential to engineer methanogenic processes to enhance the recovery of energy assets as biogenic methane from residual oils stranded in petroleum systems. Copyright 2010 Elsevier Inc. All rights reserved.

An assessment of the tracer-based approach to quantifying groundwater contributions to streamflow

NASA Astrophysics Data System (ADS)

Jones, J. P.; Sudicky, E. A.; Brookfield, A. E.; Park, Y.-J.

2006-02-01

The use of conservative geochemical and isotopic tracers along with mass balance equations to determine the pre-event groundwater contributions to streamflow during a rainfall event is widely used for hydrograph separation; however, aspects related to the influence of surface and subsurface mixing processes on the estimates of the pre-event contribution remain poorly understood. Moreover, the lack of a precise definition of "pre-event" versus "event" contributions on the one hand and "old" versus "new" water components on the other hand has seemingly led to confusion within the hydrologic community about the role of Darcian-based groundwater flow during a storm event. In this work, a fully integrated surface and subsurface flow and solute transport model is used to analyze flow system dynamics during a storm event, concomitantly with advective-dispersive tracer transport, and to investigate the role of hydrodynamic mixing processes on the estimates of the pre-event component. A number of numerical experiments are presented, including an analysis of a controlled rainfall-runoff experiment, that compare the computed Darcian-based groundwater fluxes contributing to streamflow during a rainfall event with estimates of these contributions based on a tracer-based separation. It is shown that hydrodynamic mixing processes can dramatically influence estimates of the pre-event water contribution estimated by a tracer-based separation. Specifically, it is demonstrated that the actual amount of bulk flowing groundwater contributing to streamflow may be much smaller than the quantity indirectly estimated from a separation based on tracer mass balances, even if the mixing processes are weak.

BIOPLUME MODEL FOR CONTAMINANT TRANSPORT AFFECTED BY OXYGEN LIMITED BIODEGRADATION

EPA Science Inventory

Many of the organic pollutants entering ground water are potentially biodegradable in the subsurface. This potential has been demonstrated in aquifers contaminated by wood-creosoting process wastes. The persistence of many of these organic compounds in the subsurface indicated ...

Untangling the effects of urban development on subsurface storage in Baltimore

NASA Astrophysics Data System (ADS)

Bhaskar, Aditi S.; Welty, Claire; Maxwell, Reed M.; Miller, Andrew J.

2015-02-01

The impact of urban development on surface flow has been studied extensively over the last half century, but effects on groundwater systems are still poorly understood. Previous studies of the influence of urban development on subsurface storage have not revealed any consistent pattern, with results showing increases, decreases, and negligible change in groundwater levels. In this paper, we investigated the effects of four key features that impact subsurface storage in urban landscapes. These include reduced vegetative cover, impervious surface cover, infiltration and inflow (I&I) of groundwater and storm water into wastewater pipes, and other anthropogenic recharge and discharge fluxes including water supply pipe leakage and well and reservoir withdrawals. We applied the integrated groundwater-surface water-land surface model ParFlow.CLM to the Baltimore metropolitan area. We compared the base case (all four features) to simulations in which an individual urban feature was removed. For the Baltimore region, the effect of infiltration of groundwater into wastewater pipes had the greatest effect on subsurface storage (I&I decreased subsurface storage 11.1% relative to precipitation minus evapotranspiration after 1 year), followed by the impact of water supply pipe leakage and lawn irrigation (combined anthropogenic discharges and recharges led to a 7.4% decrease) and reduced vegetation (1.9% increase). Impervious surface cover led to a small increase in subsurface storage (0.56% increase) associated with decreased groundwater discharge as base flow. The change in subsurface storage due to infiltration of groundwater into wastewater pipes was largest despite the smaller spatial extent of surface flux modifications, compared to other features.

Spatial and temporal variation of residence time and storage volume of subsurface water evaluated by multi-tracers approach in mountainous headwater catchments

NASA Astrophysics Data System (ADS)

Tsujimura, Maki; Yano, Shinjiro; Abe, Yutaka; Matsumoto, Takehiro; Yoshizawa, Ayumi; Watanabe, Ysuhito; Ikeda, Koichi

2015-04-01

Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time and stock information of the water is principal to understand hydrological processes in the catchments. However, there have been few researches to evaluate variation of residence time and storage volume of subsurface water in time and space at the mountainous headwaters especially with steep slope. We performed an investigation on age dating and estimation of storage volume using simple water budget model in subsurface water with tracing of hydrological flow processes in mountainous catchments underlain by granite, Paleozoic and Tertiary, Yamanashi and Tsukuba, central Japan. We conducted hydrometric measurements and sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2012 in the catchments, and CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Residence time of subsurface water ranged from 11 to 60 years in the granite catchments, from 17 to 32 years in the Paleozoic catchments, from 13 to 26 years in the Tertiary catchments, and showed a younger age during the high-flow season, whereas it showed an older age in the low-flow season. Storage volume of subsurface water was estimated to be ranging from 10 ^ 4 to 10 ^ 6 m3 in the granite catchments, from 10 ^ 5 to 10 ^ 7 m3 in the Paleozoic catchments, from 10 ^ 4 to 10 ^ 6 m3 in the Tertiary catchments. In addition, seasonal change of storage volume in the granite catchments was the highest as compared with those of the Paleozoic and the Tertiary catchments. The results suggest that dynamic change of hydrological process seems to cause a larger variation of the residence time and storage volume of subsurface water in time and space in the granite catchments, whereas higher groundwater recharge rate due to frequent fissures or cracks seems to cause larger storage volume of the subsurface water in the Paleozoic catchments though the variation is not so considerable. Also, numerical simulation results support these findings.

Determining temperature and thermal properties for heat-based studies of surface-water ground-water interactions: Appendix A of Heat as a tool for studying the movement of ground water near streams (Cir1260)

USGS Publications Warehouse

Stonestrom, David A.; Blasch, Kyle W.; Stonestrom, David A.; Constantz, Jim

2003-01-01

Advances in electronics leading to improved sensor technologies, large-scale circuit integration, and attendant miniaturization have created new opportunities to use heat as a tracer of subsurface flow. Because nature provides abundant thermal forcing at the land surface, heat is particularly useful in studying stream-groundwater interactions. This appendix describes methods for obtaining the thermal data needed in heat-based investigations of shallow subsurface flow.

Understanding the rapidity of subsurface storm flow response from a fracture-oriented shallow vadose through a new perspective

NASA Astrophysics Data System (ADS)

Zhao, Peng; Zhao, Pei; Liang, Chuan; Li, Tianyang; Zhou, Baojia

2017-01-01

Velocity and celerity in hydrologic systems are controlled by different mechanisms. Efforts were made through joint sample collection and the use of hydrographs and tracers to understand the rapidity of the subsurface flow response to rainstorms on hourly time scales. Three deep subsurface flows during four natural rainstorm events were monitored. The results show that (1) deeper discharge was observed early in responding rainfall events and yielded a high hydrograph amplitude; (2) a ratio index, k, reflecting the dynamic change of the rainfall perturbation intensity in subsurface flow, might reveal inner causal relationships between the flow index and the tracer signal index. Most values of k were larger than 1 at the perturbation stage but approximated 1 at the no-perturbation stage; and (3) for statistical analysis of tracer signals in subsurface flows, the total standard deviation was 17.2, 11.9, 7.4 and 3.5 at perturbation stages and 4.4, 2.5, 1.1, and 0.95 at the non-perturbation stage for observed events. These events were 3-7 times higher in the former rather than the later, reflecting that the variation of tracer signals primarily occurred under rainfall perturbation. Thus, we affirmed that the dynamic features of rainfall have a key effect on rapid processes because, besides the gravity, mechanical waves originating from dynamic rainfall features are another driving factor for conversion between different types of rainfall mechanical energy. A conceptual model for pressure wave propagation was proposed, in which virtual subsurface flow processes in a heterogeneous vadose zone under rainfall are analogous to the water hammer phenomenon in complex conduit systems. Such an analogy can allow pressure in a shallow vadose to increase and decrease and directly influence the velocity and celerity of the flow reflecting a mechanism for rapid subsurface hydrologic response processes in the shallow vadose zone.

High pressure-elevated temperature x-ray micro-computed tomography for subsurface applications.

PubMed

Iglauer, Stefan; Lebedev, Maxim

2018-06-01

Physical, chemical and mechanical pore-scale (i.e. micrometer-scale) mechanisms in rock are of key importance in many, if not all, subsurface processes. These processes are highly relevant in various applications, e.g. hydrocarbon recovery, CO 2 geo-sequestration, geophysical exploration, water production, geothermal energy production, or the prediction of the location of valuable hydrothermal deposits. Typical examples are multi-phase flow (e.g. oil and water) displacements driven by buoyancy, viscous or capillary forces, mineral-fluid interactions (e.g. mineral dissolution and/or precipitation over geological times), geo-mechanical rock behaviour (e.g. rock compaction during diagenesis) or fines migration during water production, which can dramatically reduce reservoir permeability (and thus reservoir performance). All above examples are 3D processes, and 2D experiments (as traditionally done for micro-scale investigations) will thus only provide qualitative information; for instance the percolation threshold is much lower in 3D than in 2D. However, with the advent of x-ray micro-computed tomography (μCT) - which is now routinely used - this limitation has been overcome, and such pore-scale processes can be observed in 3D at micrometer-scale. A serious complication is, however, the fact that in the subsurface high pressures and elevated temperatures (HPET) prevail, due to the hydrostatic and geothermal gradients imposed upon it. Such HPET-reservoir conditions significantly change the above mentioned physical and chemical processes, e.g. gas density is much higher at high pressure, which strongly affects buoyancy and wettability and thus gas distributions in the subsurface; or chemical reactions are significantly accelerated at increased temperature, strongly affecting fluid-rock interactions and thus diagenesis and deposition of valuable minerals. It is thus necessary to apply HPET conditions to the aforementioned μCT experiments, to be able to mimic subsurface conditions in a realistic way, and thus to obtain reliable results, which are vital input parameters required for building accurate larger-scale reservoir models which can predict the overall reservoir-scale (hectometer-scale) processes (e.g. oil production or diagenesis of a formation). We thus describe here the basic workflow of such HPET-μCT experiments, equipment requirements and apparatus design; and review the literature where such HPET-μCT experiments were used and which phenomena were investigated (these include: CO 2 geo-sequestration, oil recovery, gas hydrate formation, hydrothermal deposition/reactive flow). One aim of this paper is to give a guideline to users how to set-up a HPET-μCT experiment, and to provide a quick overview in terms of what is possible and what not, at least up to date. As a conclusion, HPET-μCT is a valuable tool when it comes to the investigation of subsurface micrometer-scaled processes, and we expect a rapidly expanding usage of HPET-μCT in subsurface engineering and the subsurface sciences. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

Tailings Pond Characterization And Designing Through Geophysical Surveys In Dipping Sedimentary Formations

NASA Astrophysics Data System (ADS)

Muralidharan, D.; Andrade, R.; Anand, K.; Sathish, R.; Goud, K.

2009-12-01

Mining activities results into generation of disintegrated waste materials attaining increased mobilization status and requires a safe disposal mechanism through back filling process or secluded storage on surface with prevention of its interaction with environment cycle. The surface disposal of waste materials will become more critical in case of mined minerals having toxic or radioactive elements. In such cases, the surface disposal site is to be characterized for its sub-surface nature to understand its role in environmental impact due to the loading of waste materials. Near surface geophysics plays a major role in mapping the geophysical characters of the sub-surface formations in and around the disposal site and even to certain extent helps in designing of the storage structure. Integrated geophysical methods involving resistivity tomography, ground magnetic and shallow seismic studies were carried out over proposed tailings pond area of 0.3 sq. kms underlined by dipping sedimentary rocks consisting of ferruginous shales and dolomitic to siliceous limestone with varying thicknesses. The investigated site being located in tectonically disturbed area, geophysical investigations were carried out with number of profiles to visualize the sub-surface nature with clarity. The integration of results of twenty profiles of resistivity tomography with 2 m (shallow) and 10 m (moderate depth) electrode spacing’s enabled in preparing probable sub-surface geological section along the strike direction of the formation under the tailings pond with some geo-tectonic structure inferred to be a fault. Similarly, two resistivity tomography profiles perpendicular to the strike direction of the formations brought out the existence of buried basic intrusive body on the northern boundary of the proposed tailings pond. Two resistivity tomography profiles in criss-cross direction over the suspected fault zone confirmed fault existence on the north-eastern part of tailings pond. Thirty two magnetic profiles inside the tailings pond and surrounding areas on the southern part of the tailings pond enabled in identifying two parallel east-west intrusive bodies forming the impermeable boundary for the tailings pond. The shallow seismic refraction and the geophysical studies in and around the proposed tailings pond brought out the suitability of the site, even when the toxic elements percolates through the subsurface formations in to the groundwater system, the existence of dykes on either side of the proposed ponding area won’t allow the water to move across them thus by restricting the contamination within the tailings pond area. Similarly, the delineation of a fault zone within the tailings pond area helped in shifting the proposed dam axis of the pond to avoid leakage through the fault zone causing concern to environment pollution.

Biodegradation of crude oil in Arctic subsurface water from the Disko Bay (Greenland) is limited.

PubMed

Scheibye, Katrine; Christensen, Jan H; Johnsen, Anders R

2017-04-01

Biological degradation is the main process for oil degradation in a subsurface oil plume. There is, however, little information on the biodegradation potential of Arctic, marine subsurface environments. We therefore investigated oil biodegradation in microcosms at 2 °C containing Arctic subsurface seawater from the Disko Bay (Greenland) and crude oil at three concentrations of 2.5-10 mg/L. Within 71 days, the total petroleum hydrocarbon concentration decreased only by 18 ± 18% for an initial concentration of 5 mg/L. The saturated alkanes nC13-nC30 and the isoprenoids iC18-iC21 were biodegraded at all concentrations indicating a substantial potential for biodegradation of these compound classes. Polycyclic aromatic compounds (PACs) disappeared from the oil phase, but dissolution was the main process of removal. Analysis of diagnostic ratios indicated almost no PAC biodegradation except for the C1-naphthalenes. To conclude, the marine subsurface microorganisms from the Disko Bay had the potential for biodegradation of n-alkanes and isoprenoids while the metabolically complex and toxic PACs and their alkylated homologs remained almost unchanged. Copyright © 2016 Elsevier Ltd. All rights reserved.

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...

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

Wainwright, Haruko M.; Flores Orozco, Adrian; Bucker, Matthias

In floodplain environments, a naturally reduced zone (NRZ) is considered to be a common biogeochemical hot spot, having distinct microbial and geochemical characteristics. Although important for understanding their role in mediating floodplain biogeochemical processes, mapping the subsurface distribution of NRZs over the dimensions of a floodplain is challenging, as conventional wellbore data are typically spatially limited and the distribution of NRZs is heterogeneous. In this work, we present an innovative methodology for the probabilistic mapping of NRZs within a three-dimensional (3-D) subsurface domain using induced polarization imaging, which is a noninvasive geophysical technique. Measurements consist of surface geophysical surveys andmore » drilling-recovered sediments at the U.S. Department of Energy field site near Rifle, CO (USA). Inversion of surface time domain-induced polarization (TDIP) data yielded 3-D images of the complex electrical resistivity, in terms of magnitude and phase, which are associated with mineral precipitation and other lithological properties. By extracting the TDIP data values colocated with wellbore lithological logs, we found that the NRZs have a different distribution of resistivity and polarization from the other aquifer sediments. To estimate the spatial distribution of NRZs, we developed a Bayesian hierarchical model to integrate the geophysical and wellbore data. In addition, the resistivity images were used to estimate hydrostratigraphic interfaces under the floodplain. Validation results showed that the integration of electrical imaging and wellbore data using a Bayesian hierarchical model was capable of mapping spatially heterogeneous interfaces and NRZ distributions thereby providing a minimally invasive means to parameterize a hydrobiogeochemical model of the floodplain.« less

Model-based Analysis of Mixed Uranium(VI) Reduction by Biotic and Abiotic Pathways During in Situ Bioremediation

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

Zhao, Jiao; Scheibe, Timothy D.; Mahadevan, Radhakrishnan

2013-10-24

Uranium bioremediation has emerged as a potential strategy of cleanup of radionuclear contamination worldwide. An integrated geochemical & microbial community model is a promising approach to predict and provide insights into the bioremediation of a complicated natural subsurface. In this study, an integrated column-scale model of uranium bioremediation was developed, taking into account long-term interactions between biotic and abiotic processes. It is also combined with a comprehensive thermodynamic analysis to track the fate and cycling of biogenic species. As compared with other bioremediation models, the model increases the resolution of the connection of microbial community to geochemistry and establishes directmore » quantitative correlation between overall community evolution and geochemical variation, thereby accurately predicting the community dynamics under different sedimentary conditions. The thermodynamic analysis examined a recently identified homogeneous reduction of U(VI) by Fe(II) under dynamic sedimentary conditions across time and space. It shows that the biogenic Fe(II) from Geobacter metabolism can be removed rapidly by the biogenic sulphide from sulfate reducer metabolism, hence constituting one of the reasons that make the abiotic U(VI) reduction thermodynamically infeasible in the subsurface. Further analysis indicates that much higher influent concentrations of both Fe(II) and U(VI) than normal are required to for abiotic U(VI) reduction to be thermodynamically feasible, suggesting that the abiotic reduction cannot be an alternative to the biotic reduction in the remediation of uranium contaminated groundwater.« less

Integrating non-colocated well and geophysical data to capture subsurface heterogeneity at an aquifer recharge and recovery site

NASA Astrophysics Data System (ADS)

Gottschalk, Ian P.; Hermans, Thomas; Knight, Rosemary; Caers, Jef; Cameron, David A.; Regnery, Julia; McCray, John E.

2017-12-01

Geophysical data have proven to be very useful for lithological characterization. However, quantitatively integrating the information gained from acquiring geophysical data generally requires colocated lithological and geophysical data for constructing a rock-physics relationship. In this contribution, the issue of integrating noncolocated geophysical and lithological data is addressed, and the results are applied to simulate groundwater flow in a heterogeneous aquifer in the Prairie Waters Project North Campus aquifer recharge site, Colorado. Two methods of constructing a rock-physics transform between electrical resistivity tomography (ERT) data and lithology measurements are assessed. In the first approach, a maximum likelihood estimation (MLE) is used to fit a bimodal lognormal distribution to horizontal crosssections of the ERT resistivity histogram. In the second approach, a spatial bootstrap is applied to approximate the rock-physics relationship. The rock-physics transforms provide soft data for multiple point statistics (MPS) simulations. Subsurface models are used to run groundwater flow and tracer test simulations. Each model's uncalibrated, predicted breakthrough time is evaluated based on its agreement with measured subsurface travel time values from infiltration basins to selected groundwater recovery wells. We find that incorporating geophysical information into uncalibrated flow models reduces the difference with observed values, as compared to flow models without geophysical information incorporated. The integration of geophysical data also narrows the variance of predicted tracer breakthrough times substantially. Accuracy is highest and variance is lowest in breakthrough predictions generated by the MLE-based rock-physics transform. Calibrating the ensemble of geophysically constrained models would help produce a suite of realistic flow models for predictive purposes at the site. We find that the success of breakthrough predictions is highly sensitive to the definition of the rock-physics transform; it is therefore important to model this transfer function accurately.

Shallow subsurface structure of the Wasatch fault, Provo segment, Utah, from integrated compressional and shear-wave seismic reflection profiles with implications for fault structure and development

USGS Publications Warehouse

McBride, J.H.; Stephenson, W.J.; Williams, R.A.; Odum, J.K.; Worley, D.M.; South, J.V.; Brinkerhoff, A.R.; Keach, R.W.; Okojie-Ayoro, A. O.

2010-01-01

Integrated vibroseis compressional and experimental hammer-source, shear-wave, seismic reflection profiles across the Provo segment of the Wasatch fault zone in Utah reveal near-surface and shallow bedrock structures caused by geologically recent deformation. Combining information from the seismic surveys, geologic mapping, terrain analysis, and previous seismic first-arrival modeling provides a well-constrained cross section of the upper ~500 m of the subsurface. Faults are mapped from the surface, through shallow, poorly consolidated deltaic sediments, and cutting through a rigid bedrock surface. The new seismic data are used to test hypotheses on changing fault orientation with depth, the number of subsidiary faults within the fault zone and the width of the fault zone, and the utility of integrating separate elastic methods to provide information on a complex structural zone. Although previous surface mapping has indicated only a few faults, the seismic section shows a wider and more complex deformation zone with both synthetic and antithetic normal faults. Our study demonstrates the usefulness of a combined shallow and deeper penetrating geophysical survey, integrated with detailed geologic mapping to constrain subsurface fault structure. Due to the complexity of the fault zone, accurate seismic velocity information is essential and was obtained from a first-break tomography model. The new constraints on fault geometry can be used to refine estimates of vertical versus lateral tectonic movements and to improve seismic hazard assessment along the Wasatch fault through an urban area. We suggest that earthquake-hazard assessments made without seismic reflection imaging may be biased by the previous mapping of too few faults. ?? 2010 Geological Society of America.

Integrating remote sensing and subsurface geological data to characterize a tidally-influenced paleodrainage from the mid-late Holocene succession of the Po Delta Plain (Italy)

NASA Astrophysics Data System (ADS)

Giacomelli, Serena; Rossi, Veronica; Amorosi, Alessandro; Bruno, Luigi; Campo, Bruno; Ciampalini, Andrea; Civa, Andrea; de Souza Filho, Roberto Carlos; Sgavetti, Maria

2017-04-01

A tidally-influenced, mid-late Holocene paleodrainage system from the Po Delta Plain (N Adriatic Sea, Italy) is reconstructed coupling remote sensing (RS) and subsurface geological data. Optical satellite images, DTM LiDAR, soil reflectance spectral features and core stratigraphy were combined in a GIS environment following a fully integrated methodological approach. The stratigraphic significance of RS-derived data (traces) was defined in terms of both depositional facies and depth, furnishing new insights on the role of RS in reconstructing the recent evolution of paleodrainages in coastal-deltaic settings. Sixteen images from Landsat 7 ETM+ (Enhanced Thematic Mapper Plus), Landsat 8 OLI (Operational Land Imager), Sentinel-2 MSI (Multispectral Instruments), and Hyperion satellites were collected from the USGS and the Scientific Hub ESA-Copernicus on-line databases, and integrated with Google Earth imagery. The visual interpretation of the images, mostly based on the brightness contrast (high and low reflectance values) and aimed to the recognition of traces, has been facilitated by the RGB combinations of the spectral bands most sensitive to lithology and moisture content and supported by a semi-automatic processing, including unsupervised classification and the spectral bands Principal Component Analysis (PCA). Multitemporal analysis of satellite imagery have been also performed. Two main traces, interpreted as meanders, have been analyzed for their sedimentological and stratigraphic characteristics. Following a field survey aimed to describe the morphology, grain-size, colors, and accessory materials of surface deposits, 11 soil samples have been collected for the extraction of the reflectance spectral signature and coring along the traces and in adjacent areas (bright and dark portions). Cores have been sampled for benthic foraminifer/ostracod analysis (42 samples) and stratigraphic cross-sections were constructed transversal to the meandering traces. Nine radiocarbon ages allowed to set the depositional evolution of the two meanders into a definite chronological framework. The integrated, RS-stratigraphic methodological approach revealed a meandering paleodrainage system buried > 2 m below the ground level. Its surface visibility is guided by the spatial distribution of surface moisture, which mainly depends on subsurface stratigraphic architecture and, in particular, on the distribution of organic-rich deposits laterally to the migrating meanders. The formation and activity of the buried paleochannels dates back to the early Holocene highstand (6000-2500 cal yr BP), when a drainage system likely developed under tide-influenced conditions.

Estimating and mapping ecological processes influencing microbial community assembly

DOE PAGES

Stegen, James C.; Lin, Xueju; Fredrickson, Jim K.; ...

2015-05-01

Ecological community assembly is governed by a combination of (i) selection resulting from among-taxa differences in performance; (ii) dispersal resulting from organismal movement; and (iii) ecological drift resulting from stochastic changes in population sizes. The relative importance and nature of these processes can vary across environments. Selection can be homogeneous or variable, and while dispersal is a rate, we conceptualize extreme dispersal rates as two categories; dispersal limitation results from limited exchange of organisms among communities, and homogenizing dispersal results from high levels of organism exchange. To estimate the influence and spatial variation of each process we extend a recentlymore » developed statistical framework, use a simulation model to evaluate the accuracy of the extended framework, and use the framework to examine subsurface microbial communities over two geologic formations. For each subsurface community we estimate the degree to which it is influenced by homogeneous selection, variable selection, dispersal limitation, and homogenizing dispersal. Our analyses revealed that the relative influences of these ecological processes vary substantially across communities even within a geologic formation. We further identify environmental and spatial features associated with each ecological process, which allowed mapping of spatial variation in ecological-process-influences. The resulting maps provide a new lens through which ecological systems can be understood; in the subsurface system investigated here they revealed that the influence of variable selection was associated with the rate at which redox conditions change with subsurface depth.« less

Prospects of passive radio detection of a subsurface ocean on Europa with a lander

NASA Astrophysics Data System (ADS)

Romero-Wolf, Andrew; Schroeder, Dustin M.; Ries, Paul; Bills, Bruce G.; Naudet, Charles; Scott, Bryan R.; Treuhaft, Robert; Vance, Steve

2016-09-01

We estimate the sensitivity of a lander-based instrument for the passive radio detection of a subsurface ocean beneath the ice shell of Europa, expected to be between 3 km and 30 km thick, using Jupiter's decametric radiation. A passive technique was previously studied for an orbiter. Using passive detection in a lander platform provides a point measurement with significant improvements due to largely reduced losses from surface roughness effects, longer integration times, and diminished dispersion due to ionospheric effects allowing operation at lower frequencies and a wider band. A passive sounder on-board a lander provides a low resource instrument sensitive to subsurface ocean at Europa up to depths of 6.9 km for high loss ice (16 dB/km two-way attenuation rate) and 69 km for pure ice (1.6 dB/km).

Fractal topography and subsurface water flows from fluvial bedforms to the continental shield

USGS Publications Warehouse

Worman, A.; Packman, A.I.; Marklund, L.; Harvey, J.W.; Stone, S.H.

2007-01-01

Surface-subsurface flow interactions are critical to a wide range of geochemical and ecological processes and to the fate of contaminants in freshwater environments. Fractal scaling relationships have been found in distributions of both land surface topography and solute efflux from watersheds, but the linkage between those observations has not been realized. We show that the fractal nature of the land surface in fluvial and glacial systems produces fractal distributions of recharge, discharge, and associated subsurface flow patterns. Interfacial flux tends to be dominated by small-scale features while the flux through deeper subsurface flow paths tends to be controlled by larger-scale features. This scaling behavior holds at all scales, from small fluvial bedforms (tens of centimeters) to the continental landscape (hundreds of kilometers). The fractal nature of surface-subsurface water fluxes yields a single scale-independent distribution of subsurface water residence times for both near-surface fluvial systems and deeper hydrogeological flows. Copyright 2007 by the American Geophysical Union.

Evaluation of Surface and Subsurface Processes in Permeable Pavement Infiltration Trenches

EPA Science Inventory

The hydrologic performance of permeable pavement systems can be affected by clogging of the pavement surface and/or clogging at the interface where the subsurface storage layer meets the underlying soil. As infiltration and exfiltration are the primary functional mechanisms for ...

RESEARCH ACTIVITIES AT U.S. GOVERNMENT AGENCIES IN SUBSURFACE REACTIVE TRANSPORT MODELING

EPA Science Inventory

The fate of contaminants in the environment is controlled by both chemical reactions and transport phenomena in the subsurface. Our ability to understand the significance of these processes over time requires an accurate conceptual model that incorporates the various mechanisms ...

3D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface

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

Levander, Alan Richard; Zelt, Colin A.

2015-03-17

The work plan for this project was to develop and apply advanced seismic reflection and wide-angle processing and inversion techniques to high resolution seismic data for the shallow subsurface to seismically characterize the shallow subsurface at hazardous waste sites as an aid to containment and cleanup activities. We proposed to continue work on seismic data that we had already acquired under a previous DoE grant, as well as to acquire additional new datasets for analysis. The project successfully developed and/or implemented the use of 3D reflection seismology algorithms, waveform tomography and finite-frequency tomography using compressional and shear waves for highmore » resolution characterization of the shallow subsurface at two waste sites. These two sites have markedly different near-surface structures, groundwater flow patterns, and hazardous waste problems. This is documented in the list of refereed documents, conference proceedings, and Rice graduate theses, listed below.« less

Key subsurface data help to refine Trinity aquifer hydrostratigraphic units, south-central Texas

USGS Publications Warehouse

Blome, Charles D.; Clark, Allan K.

2014-01-01

The geologic framework and hydrologic characteristics of aquifers are important components for studying the nation’s subsurface heterogeneity and predicting its hydraulic budgets. Detailed study of an aquifer’s subsurface hydrostratigraphy is needed to understand both its geologic and hydrologic frameworks. Surface hydrostratigraphic mapping can also help characterize the spatial distribution and hydraulic connectivity of an aquifer’s permeable zones. Advances in three-dimensional (3-D) mapping and modeling have also enabled geoscientists to visualize the spatial relations between the saturated and unsaturated lithologies. This detailed study of two borehole cores, collected in 2001 on the Camp Stanley Storage Activity (CSSA) area, provided the foundation for revising a number of hydrostratigraphic units representing the middle zone of the Trinity aquifer. The CSSA area is a restricted military facility that encompasses approximately 4,000 acres and is located in Boerne, Texas, northwest of the city of San Antonio. Studying both the surface and subsurface geology of the CSSA area are integral parts of a U.S. Geological Survey project funded through the National Cooperative Geologic Mapping Program. This modification of hydrostratigraphic units is being applied to all subsurface data used to construct a proposed 3-D EarthVision model of the CSSA area and areas to the south and west.

Subsurface structures of buried features in the lunar Procellarum region

NASA Astrophysics Data System (ADS)

Wang, Wenrui; Heki, Kosuke

2017-07-01

The Gravity Recovery and Interior Laboratory (GRAIL) mission unraveled numbers of features showing strong gravity anomalies without prominent topographic signatures in the lunar Procellarum region. These features, located in different geologic units, are considered to have complex subsurface structures reflecting different evolution processes. By using the GRAIL level-1 data, we estimated the free-air and Bouguer gravity anomalies in several selected regions including such intriguing features. With the three-dimensional inversion technique, we recovered subsurface density structures in these regions.

Assessment of DInSAR Potential in Simulating Geological Subsurface Structure

NASA Astrophysics Data System (ADS)

Fouladi Moghaddam, N.; Rudiger, C.; Samsonov, S. V.; Hall, M.; Walker, J. P.; Camporese, M.

2013-12-01

High resolution geophysical surveys, including seismic, gravity, magnetic, etc., provide valuable information about subsurface structuring but they are very costly and time consuming with non-unique and sometimes conflicting interpretations. Several recent studies have examined the application of DInSAR to estimate surface deformation, monitor possible fault reactivation and constrain reservoir dynamic behaviour in geothermal and groundwater fields. The main focus of these studies was to generate an elevation map, which represents the reservoir extraction induced deformation. This research study, however, will focus on developing methods to simulate subsurface structuring and identify hidden faults/hydraulic barriers using DInSAR surface observations, as an innovative and cost-effective reconnaissance exploration tool for planning of seismic acquisition surveys in geothermal and Carbon Capture and Sequestration regions. By direct integration of various DInSAR datasets with overlapping temporal and spatial coverage we produce multi-temporal ground deformation maps with high resolution and precision to evaluate the potential of a new multidimensional MSBAS technique (Samsonov & d'Oreye, 2012). The technique is based on the Small Baseline Subset Algorithm (SBAS) that is modified to account for variation in sensor parameters. It allows integration of data from sensors with different wave-band, azimuth and incidence angles, different spatial and temporal sampling and resolutions. These deformation maps then will be used as an input for inverse modelling to simulate strain history and shallow depth structure. To achieve the main objective of our research, i.e. developing a method for coupled InSAR and geophysical observations and better understanding of subsurface structuring, comparing DInSAR inverse modelling results with previously provided static structural model will result in iteratively modified DInSAR structural model for adequate match with in situ observations. The newly developed and modified algorithm will then be applied in another part of the region where subsurface information is limited.

Advances in Multiphase Flow and Transport in the Subsurface Environment

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

Shi, Xiaoqing; Finsterle, Stefan; Zhang, Keni

Multiphase flow and transport processes in the subsurface environment are extremely important in a number of industrial and environmental applications at various spatial and temporal scales. Thus, it is necessary to identify, understand, and predict these processes to improve the production of conventional and unconventional oil and gas, to increase the safety of geological sequestration of carbon dioxide and nuclear waste disposal, and to make remediation of contaminated aquifers more effective.

Advances in Multiphase Flow and Transport in the Subsurface Environment

DOE PAGES

Shi, Xiaoqing; Finsterle, Stefan; Zhang, Keni; ...

2018-03-04

Multiphase flow and transport processes in the subsurface environment are extremely important in a number of industrial and environmental applications at various spatial and temporal scales. Thus, it is necessary to identify, understand, and predict these processes to improve the production of conventional and unconventional oil and gas, to increase the safety of geological sequestration of carbon dioxide and nuclear waste disposal, and to make remediation of contaminated aquifers more effective.

Laser-assisted focused He + ion beam induced etching with and without XeF 2 gas assist

DOE PAGES

Stanford, Michael G.; Mahady, Kyle; Lewis, Brett B.; ...

2016-10-04

Focused helium ion (He +) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF 2 precursor provides a chemical assist for enhanced material removal rate. In conclusion, amore » pulsed laser-assisted and gas-assisted FIBIE process is shown to increase the etch yield by ~9× relative to the pure He+ sputtering process. These He + induced nanopatterning techniques improve material removal rate, in comparison to standard He + sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He + probe as a nanopattering tool.« less

Laser-assisted focused He + ion beam induced etching with and without XeF 2 gas assist

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

Stanford, Michael G.; Mahady, Kyle; Lewis, Brett B.

Focused helium ion (He +) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF 2 precursor provides a chemical assist for enhanced material removal rate. In conclusion, amore » pulsed laser-assisted and gas-assisted FIBIE process is shown to increase the etch yield by ~9× relative to the pure He+ sputtering process. These He + induced nanopatterning techniques improve material removal rate, in comparison to standard He + sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He + probe as a nanopattering tool.« less

ENVIRONMENTAL IMPACTS AND MONITORING: A HISTORICAL PERSPECTIVE ON THE USE OF NATURAL ATTENUATION FOR SUBSURFACE REMEDIATION

EPA Science Inventory

The collective processes that constitute the broadly used term Anatural attenuation,@ as it relates to subsurface remediation of contaminants, refer to the physical, chemical, and biological interactions that, without human intervention, reduce or contain contaminants in the sub...

SEQUESTRATION OF SUBSURFACE ELEMENTAL MERCURY (HG0)

EPA Science Inventory

Elemental mercury (Hg⁰) is a metal with a number of atypical properties, which has resulted in its use in myriad anthropogenic processes. However, these same properties have also led to severe local subsurface contamination at many places where it has been used. As...

Simulating land-atmosphere feedbacks and response to widespread forest disturbance: The role of lower boundary configuration and dynamic water table in meteorological modeling

NASA Astrophysics Data System (ADS)

Forrester, M.; Maxwell, R. M.; Bearup, L. A.; Gochis, D.

2017-12-01

Numerical meteorological models are frequently used to diagnose land-atmosphere interactions and predict large-scale response to extreme or hazardous events, including widespread land disturbance or perturbations to near-surface moisture. However, few atmospheric modeling platforms consider the impact that dynamic groundwater storage, specifically 3D subsurface flow, has on land-atmosphere interactions. In this study, we use the Weather Research and Forecasting (WRF) mesoscale meteorological model to identify ecohydrologic and land-atmosphere feedbacks to disturbance by the mountain pine beetle (MPB) over the Colorado Headwaters region. Disturbance simulations are applied to WRF with various lower boundary configurations: Including default Noah land surface model soil moisture representation; a version of WRF coupled to ParFlow (PF), an integrated groundwater-surface water model that resolves variably saturated flow in the subsurface; and WRF coupled to PF in a static water table version, simulating only vertical and no lateral subsurface flow. Our results agree with previous literature showing MPB-induced reductions in canopy transpiration in all lower boundary scenarios, as well as energy repartitioning, higher water tables, and higher planetary boundary layer over infested regions. Simulations show that expanding from local to watershed scale results in significant damping of MPB signal as unforested and unimpacted regions are added; and, while deforestation appears to have secondary feedbacks to planetary boundary layer and convection, these slight perturbations to cumulative summer precipitation are insignificant in the context of ensemble methodologies. Notably, the results suggest that groundwater representation in atmospheric modeling affects the response intensity of a land disturbance event. In the WRF-PF case, energy and atmospheric processes are more sensitive to disturbance in regions with higher water tables. Also, when dynamic subsurface hydrology is removed, WRF simulates a greater response to MPB at the land-atmosphere interface, including greater changes to daytime skin temperature, Bowen ratio and near-surface humidity. These findings highlight lower boundary representations in computational meteorology and numerical land-atmosphere modeling.

The Integration of GPR, GIS, and GPS for 3D Soil Morphologic Models

NASA Astrophysics Data System (ADS)

Tischler, M.; Collins, M. E.

2005-05-01

Ground-Penetrating Radar (GPR) has become a useful and efficient instrument for gathering information about subsurface diagnostic horizons in Florida soils. Geographic Information Systems (GIS) are a popular and valuable tool for spatial data analysis of real world features in a digital environment. Ground-Penetrating Radar can be linked to GIS by using Global Positioning Systems (GPS). By combining GPR, GPS, and GIS technologies, a more detailed geophysical survey can be completed for an area of interest by integratinghydrologic, pedologic, and geologic data. Thus, the objectives of this research were to identify subsurface soil layers using GPR and their geographic position with a highly accurate GPS; to develop a procedure to import GPR data into a popular software package, such as ArcGIS, and; to create 3D subsurface models based on the imported GPR data. The site for this study was the Plant Science Research and Education Center in Marion County, Florida. The soils are characterized by Recent-Pleistocene-age sand over the clayey, marine deposited Plio-Miocene-age Hawthorn Formation which drapes the Eocene-age Ocala Limestone. Consequently, soils in the research area vary from deep quartz sands (Typic Quartzipsamments) to shallow outcrops of the Hawthorn Formation (Arenic Hapludalfs). A GPR survey was performed on a 160 m x 320 m grid to gather data for processing. Four subsurface models estimating the depth to argillic horizon were created using a variety of specialized GPR data filters and geostatistical data analyses. The models were compared with ground-truth points that measured the depth to argillic horizon to validate each model and calculate error metrics. These models may assist research station personnel to determine best management practices (including experimental plot placement, irrigation management, fertilizer treatment, and pesticide applications). In addition, the developed methodology exploits the potential of combining GPR and GIS.

Reconstruction of sub-surface archaeological remains from magnetic data using neural computing.

NASA Astrophysics Data System (ADS)

Bescoby, D. J.; Cawley, G. C.; Chroston, P. N.

2003-04-01

The remains of a former Roman colonial settlement, once part of the classical city of Butrint in southern Albania have been the subject of a high resolution magnetic survey using a caesium-vapour magnetometer. The survey revealed the surviving remains of an extensive planned settlement and a number of outlying buildings, today buried beneath over 0.5 m of alluvial deposits. The aim of the current research is to derive a sub-surface model from the magnetic survey measurements, allowing an enhanced archaeological interpretation of the data. Neural computing techniques are used to perform the non-linear mapping between magnetic data and corresponding sub-surface model parameters. The adoption of neural computing paradigms potentially holds several advantages over other modelling techniques, allowing fast solutions for complex data, while having a high tolerance to noise. A multi-layer perceptron network with a feed-forward architecture is trained to estimate the shape and burial depth of wall foundations using a series of representative models as training data. Parameters used to forward model the training data sets are derived from a number of trial trench excavations targeted over features identified by the magnetic survey. The training of the network was optimized by first applying it to synthetic test data of known source parameters. Pre-processing of the network input data, including the use of a rotationally invariant transform, enhanced network performance and the efficiency of the training data. The approach provides good results when applied to real magnetic data, accurately predicting the depths and layout of wall foundations within the former settlement, verified by subsequent excavation. The resulting sub-surface model is derived from the averaged outputs of a ‘committee’ of five networks, trained with individualized training sets. Fuzzy logic inference has also been used to combine individual network outputs through correlation with data from a second geophysical technique, allowing the integration of data from a separate series of measurements.

Importance of solar subsurface heating in ocean general circulation models

NASA Astrophysics Data System (ADS)

Rochford, Peter A.; Kara, A. Birol; Wallcraft, Alan J.; Arnone, Robert A.

2001-12-01

The importance of subsurface heating on surface mixed layer properties in an ocean general circulation model (OGCM) is examined using attenuation of solar irradiance with depth below the ocean surface. The depth-dependent attenuation of subsurface heating is given by global monthly mean fields for the attenuation of photosynthetically available radiation (PAR), kPAR. These global fields of kPAR are derived from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data on the spectral diffuse attenuation coefficient at 490 nm (k490), and have been processed to have the smoothly varying and continuous coverage necessary for use in OGCM applications. These monthly fields provide the first complete global data sets of subsurface optical fields that can be used for OGCM applications of subsurface heating and bio-optical processes. The effect on global OGCM prediction of sea surface temperature (SST) and surface mixed layer depth (MLD) is examined when solar heating, as given by monthly mean kPAR and PAR fields, is included in the model. It is found that subsurface heating yields a marked increase in the SST predictive skill of the OGCM at low latitudes. No significant improvement in MLD predictive skill is obtained when including subsurface heating. Use of the monthly mean kPAR produces an SST decrease of up to 0.8°C and a MLD increase of up to only 4-5 m for climatological surface forcing, with this primarily confined to the equatorial regions. Remarkably, a constant kPAR value of 0.06 m-1, which is indicative of optically clear open ocean conditions, is found to serve very well for OGCM prediction of SST and MLD over most of the global ocean.

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.

Research on subsurface deformed layer in ultra-precision cutting of single crystal copper by focused ion beam etching method

NASA Astrophysics Data System (ADS)

Chen, Y.; Huang, X. J.; Kong, J. X.

2018-03-01

In this paper, the focused ion beam was used to study the subsurface deformed layer of single crystal copper caused by the nanoscale single-point diamond fly cutting, and the possibility of using nanometer ultra-precision cutting to remove the larger deformation layer caused by traditional rough cutting process was explored. The maximum cutting thickness of single-point diamond cutting was about 146 nm, and the surface of the single-crystal copper after cutting was etched and observed by using the focused ion beam method. It was found that the morphology of the near-surface layer and the intermediate layer of the copper material were larger differences: the near-surface of the material was smaller and more compact, and the intermediate material layer of the material was more coarse sparse. The results showed that the traditional precision cutting would residual significant subsurface deformed layer and the thickness was on micron level. Even more, the subsurface deformed layer was obviously removed from about 12μm to 5μm after single-point diamond fly cutting in this paper. This paper proved that the large-scale subsurface deformed layer caused by traditional cutting process could be removed by nanometer ultra-precision cutting. It was of great significance to further establish the method that control of the deformation of weak rigid components by reducing the depth of the subsurface deformed layers.

Predicting Plant-Accessible Water in the Critical Zone: Mountain Ecosystems in a Mediterranean Climate

NASA Astrophysics Data System (ADS)

Klos, P. Z.; Goulden, M.; Riebe, C. S.; Tague, C.; O'Geen, A. T.; Flinchum, B. A.; Safeeq, M.; Conklin, M. H.; Hart, S. C.; Asefaw Berhe, A.; Hartsough, P. C.; Holbrook, S.; Bales, R. C.

2017-12-01

Enhanced understanding of subsurface water storage, and the below-ground architecture and processes that create it, will advance our ability to predict how the impacts of climate change - including drought, forest mortality, wildland fire, and strained water security - will take form in the decades to come. Previous research has examined the importance of plant-accessible water in soil, but in upland landscapes within Mediterranean climates the soil is often only the upper extent of subsurface water storage. We draw insights from both this previous research and a case study of the Southern Sierra Critical Zone Observatory to: define attributes of subsurface storage, review observed patterns in its distribution, highlight nested methods for its estimation across scales, and showcase the fundamental processes controlling its formation. We observe that forest ecosystems at our sites subsist on lasting plant-accessible stores of subsurface water during the summer dry period and during multi-year droughts. This indicates that trees in these forest ecosystems are rooted deeply in the weathered, highly porous saprolite, which reaches up to 10-20 m beneath the surface. This confirms the importance of large volumes of subsurface water in supporting ecosystem resistance to climate and landscape change across a range of spatiotemporal scales. This research enhances the ability to predict the extent of deep subsurface storage across landscapes; aiding in the advancement of both critical zone science and the management of natural resources emanating from similar mountain ecosystems worldwide.

Exploring the role of mixing between subsurface flow paths on transit time distributions using a Lagrangian model

NASA Astrophysics Data System (ADS)

Zehe, Erwin; Jackisch, Conrad; Rodriguez, Nicolas; Klaus, Julian

2017-04-01

Only a minute amount of global fresh water is stored in the unsaturated zone. Yet this tiny compartment controls soil microbial activity and associated trace gas emissions, transport and transformations of contaminants, plant productivity, runoff generation and groundwater recharge. To date, the processes controlling renewal and age of different fractions of the soil water stock are far from being understood. Current theories and process concepts were largely inferred either from over-simplified laboratory experiments, or non-exhaustive point observations and tracer data in the field. Tracer data provide key but yet integrated information about the distribution of travel times of the tracer molecules to a certain depth or on their travel depth distribution within a given time. We hence are able to observe the "effect" of soil structure i.e. partitioning of infiltrating water between fast preferential and slow flow paths and imperfect subsequent mixing between these flow paths in the subsurface and the related plant water uptake. However, we are not able to study the "cause" - because technologies for in-situ observations of flow, flow path topology and exchange processes at relevant interfaces have up to now not been at hand. In the present study we will make use of a Lagrangian model for subsurface water dynamics to explore how subsurface heterogeneity and mixing among different storage fractions affects residence time distribution in the unsaturated zone in a forward approach. Soil water is represented by particles of constant mass, which travel according to the Itô form of the Fokker Planck equation. The model concept builds on established soil physics by estimating the drift velocity and the diffusion term based on the soil water characteristics. The model has been shown to simulate capillary driven soil moisture dynamics in good accordance with a) the Richards equation and b) observed soil moisture data in different soil. The particle model may furthermore account for preferential non equilibrium infiltration in a straightforward manner by treating event water as different type of particle, which travel initially in a macropore/ coarse pore fraction and experience a slow diffusive mixing with the pre-event water particles within a characteristic mixing time. In the present study we will particularly use the last approach in combination with artificial tracer data and stable isotopes to explore how different assumptions on mixing between different flow paths affect the travel time and residence time distributions of water particles in different fractions of the pore space.

Integrating 3D geological information with a national physically-based hydrological modelling system

NASA Astrophysics Data System (ADS)

Lewis, Elizabeth; Parkin, Geoff; Kessler, Holger; Whiteman, Mark

2016-04-01

Robust numerical models are an essential tool for informing flood and water management and policy around the world. Physically-based hydrological models have traditionally not been used for such applications due to prohibitively large data, time and computational resource requirements. Given recent advances in computing power and data availability, a robust, physically-based hydrological modelling system for Great Britain using the SHETRAN model and national datasets has been created. Such a model has several advantages over less complex systems. Firstly, compared with conceptual models, a national physically-based model is more readily applicable to ungauged catchments, in which hydrological predictions are also required. Secondly, the results of a physically-based system may be more robust under changing conditions such as climate and land cover, as physical processes and relationships are explicitly accounted for. Finally, a fully integrated surface and subsurface model such as SHETRAN offers a wider range of applications compared with simpler schemes, such as assessments of groundwater resources, sediment and nutrient transport and flooding from multiple sources. As such, SHETRAN provides a robust means of simulating numerous terrestrial system processes which will add physical realism when coupled to the JULES land surface model. 306 catchments spanning Great Britain have been modelled using this system. The standard configuration of this system performs satisfactorily (NSE > 0.5) for 72% of catchments and well (NSE > 0.7) for 48%. Many of the remaining 28% of catchments that performed relatively poorly (NSE < 0.5) are located in the chalk in the south east of England. As such, the British Geological Survey 3D geology model for Great Britain (GB3D) has been incorporated, for the first time in any hydrological model, to pave the way for improvements to be made to simulations of catchments with important groundwater regimes. This coupling has involved development of software to allow for easy incorporation of geological information into SHETRAN for any model setup. The addition of more realistic subsurface representation following this approach is shown to greatly improve model performance in areas dominated by groundwater processes. The resulting modelling system has great potential to be used as a resource at national, regional and local scales in an array of different applications, including climate change impact assessments, land cover change studies and integrated assessments of groundwater and surface water resources.

Linking Metabolism, Elemental Cycles, and Environmental Conditions in the Deep Biosphere: Growth of a Model Extremophile, Archaeoglobus fulgidus, Under High-Pressure Conditions

NASA Astrophysics Data System (ADS)

Oliver, G. C. M.; Cario, A.; Rogers, K. L.

2015-12-01

A majority of Earth's biosphere is hosted in subsurface environments where global-scale biogeochemical and energy cycles are driven by diverse microbial communities that operate on and are influenced by micro-scale environmental variables. While the subsurface hosts a variety of geochemical and geothermal conditions, elevated pressures are common to all subsurface ecosystems. Understanding how microbes adapt to and thrive in high-pressure environments is essential to linking microbial subsurface processes with global-scale cycles. Here we are using a model extremophile, Archaeoglobus fulgidus, to determine how elevated pressures affect the growth, metabolism, and physiology of subsurface microorganisms. A. fulgidus cycles carbon and sulfur via heterotrophic and autotrophic sulfate reduction in various high temperature and high-pressure niches including shallow marine vents, deep-sea hydrothermal vents, and deep oil reservoirs. Here we report the results of A. fulgidus growth experiments at optimum temperature, 83°C, and pressures up to 600 bars. Exponential growth was observed over the entire pressure range, though growth rates were diminished at 500 and 600 bars compared to ambient pressure experimental controls. At pressures up to 400 bars, cell density yields and growth rates were at least as high as ambient pressure controls. Elevated pressures and extended incubation times stimulated cell flocculation, a common stress response in this strain, and cellular morphology was affected at pressures exceeding 400 bars. These results suggest that A. fulgidus continues carbon, sulfur and energy cycling unaffected by elevated pressures up to 400 bars, representing a variety of subsurface environments. The ability of subsurface organisms to drive biogeochemical cycles at elevated pressures is a critical link between the surface and subsurface biospheres and understanding how species-scale processes operate under these conditions is a vital part of global-scale biogeochemical models.

Biofilm-induced calcium carbonate precipitation: application in the subsurface

NASA Astrophysics Data System (ADS)

Phillips, A. J.; Eldring, J.; Lauchnor, E.; Hiebert, R.; Gerlach, R.; Mitchell, A. C.; Esposito, R.; Cunningham, A. B.; Spangler, L.

2012-12-01

We have investigated mitigation strategies for sealing high permeability regions, like fractures, in the subsurface. This technology has the potential to, for example, improve the long-term security of geologically-stored carbon dioxide (CO2) by sealing fractures in cap rocks or to mitigate leakage pathways to prevent contamination of overlying aquifers from hydraulic fracturing fluids. Sealing technologies using low-viscosity fluids are advantageous since they potentially reduce the necessary injection pressures and increase the radius of influence around injection wells. In this technology, aqueous solutions and suspensions are used to promote microbially-induced mineral precipitation which can be applied in subsurface environments. To this end, a strategy was developed to twice seal a hydraulically fractured, 74 cm (2.4') diameter Boyles Sandstone core, collected in North-Central Alabama, with biofilm-induced calcium carbonate (CaCO3) precipitates under ambient pressures. Sporosarcina pasteurii biofilms were established and calcium and urea containing reagents were injected to promote saturation conditions favorable for CaCO3 precipitation followed by growth reagents to resuscitate the biofilm's ureolytic activity. Then, in order to evaluate this process at relevant deep subsurface pressures, a novel high pressure test vessel was developed to house the 74 cm diameter core under pressures as high as 96 bar (1,400 psi). After determining that no impact to the fracture permeability occurred due to increasing overburden pressure, the fractured core was sealed under subsurface relevant pressures relating to 457 meters (1,500 feet) below ground surface (44 bar (650 psi) overburden pressure). After fracture sealing under both ambient and subsurface relevant pressure conditions, the sandstone core withstood three times higher well bore pressure than during the initial fracturing event, which occurred prior to biofilm-induced CaCO3 mineralization. These studies suggest biofilm-induced CaCO3 precipitation technologies may potentially seal and strengthen high permeability regions or fractures (either natural or induced) in the subsurface. Novel high pressure test vessel to investigate biogeochemical processes under relevant subsurface scales and pressures.

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.

A wavefront reconstruction method for 3-D cylindrical subsurface radar imaging.

PubMed

Flores-Tapia, Daniel; Thomas, Gabriel; Pistorius, Stephen

2008-10-01

In recent years, the use of radar technology has been proposed in a wide range of subsurface imaging applications. Traditionally, linear scan trajectories are used to acquire data in most subsurface radar applications. However, novel applications, such as breast microwave imaging and wood inspection, require the use of nonlinear scan trajectories in order to adjust to the geometry of the scanned area. This paper proposes a novel reconstruction algorithm for subsurface radar data acquired along cylindrical scan trajectories. The spectrum of the collected data is processed in order to locate the spatial origin of the target reflections and remove the spreading of the target reflections which results from the different signal travel times along the scan trajectory. The proposed algorithm was successfully tested using experimental data collected from phantoms that mimic high contrast subsurface radar scenarios, yielding promising results. Practical considerations such as spatial resolution and sampling constraints are discussed and illustrated as well.

Modeling the processing of interstellar ices by energetic particles

NASA Astrophysics Data System (ADS)

Kalvāns, J.; Shmeld, I.

2013-06-01

Context. Interstellar ice is the main form of metal species in dark molecular clouds. Experiments and observations have shown that the ice is significantly processed after the freeze-out of molecules onto grains. The processing is caused by cosmic-ray particles and cosmic-ray-induced UV photons. These transformations are included in current astrochemical models only to a very limited degree. Aims: We aim to establish a model of the "cold" chemistry in interstellar ices and to evaluate its general impact on the composition of interstellar ices. Methods: The ice was treated as consisting of two layers - the surface and the mantle (or subsurface) layer. Subsurface chemical processes are described with photodissociation of ice species and binary reactions on the surfaces of cavities inside the mantle. Hydrogen atoms and molecules can diffuse between the layers. We also included deuterium chemistry. Results: The modeling results show that the content of chemically bound H is reduced in subsurface molecules by about 30% on average. This promotes the formation of more hydrogen-poor species in the ice. The enrichment of ice molecules with deuterium is significantly reduced by the subsurface processes. On average, it follows the gas-phase atomic D/H abundance ratio, with a delay. The delay produced by the model is on the order of several Myr. Conclusions: The processing of ice may place new constraints on the production of deuterated species on grains. In a mantle with a two-layer structure the upper layer (CO) should be processed substantially more intensively than the lower layer (H2O). Chemical explosions in interstellar ice might not be an important process. They destroy the structure of the mantle, which forms over long timescales. Besides, ices may lack the high radical content needed for the explosions.

Caries-preventive effect of fissure sealant containing surface reaction-type pre-reacted glass ionomer filler and bonded by self-etching primer.

PubMed

Shimazu, Kisaki; Ogata, Kiyokazu; Karibe, Hiroyuki

2012-01-01

We aimed to evaluate the caries-preventive effect of a fissure sealant containing surface reaction-type pre-reacted glass ionomer (S-PRG) filler and bonded by self-etching primer versus those of 2 conventional resin-based sealants bonded by acid etching in terms of its impact on enamel demineralization and remineralization, enamel bond strength, and integrity of debonded enamel surfaces. Demineralization, remineralization, and bond strength on untreated enamel and enamel subsurface lesions of bovine incisors were assessed among the sealants by polarizing microscopy and microradiography; debonded enamel surfaces were examined by scanning electron microscopy. The conventional resin-based sealants bonded by acid etching caused surface defects on the enamel subsurface lesions and significantly increased the lesion depth (p = 0.014), indicative of enamel demineralization. However the S-PRG filler-containing sealant bonded by self-etching primer maintained the enamel surface integrity and inhibited enamel demineralization. No difference in bond strength on both untreated enamel and enamel subsurface lesions was noted among the sealants. An S-PRG filler-containing fissure sealant bonded by self-etching primer can prevent enamel demineralization, microleakage, and gaps without the tags created by acid etching regardless of the enamel condition. Such sealants are suitable for protecting the pits and fissures of immature permanent teeth.

COUPLED IRON CORROSION AND CHROMATE REDUCTION: MECHANISMS FOR SUBSURFACE REMEDIATION

EPA Science Inventory

The reduction of chromium from the Cr(VI) to the Cr- (Ill) state by the presence of elemental, or zero-oxidation-state, iron metal was studied to evaluate the feasibility of such a process for subsurface chromate remediation. Reactions were studied in systems of natural aquifer m...

INLAND DISSOLVED SALT CHEMISTRY: STATISTICAL EVALUATION OF BIVARIATE AND TERNARY DIAGRAM MODELS FOR SURFACE AND SUBSURFACE WATERS

EPA Science Inventory

We compared the use of ternary and bivariate diagrams to distinguish the effects of atmospheric precipitation, rock weathering, and evaporation on inland surface and subsurface water chemistry. The three processes could not be statistically differentiated using bivariate models e...

Ground Water Issue. BASIC CONCEPTS OF CONTAMINANT SORPTION AT HAZARDOUS WASTE SITES

EPA Science Inventory

One of the major issues of concern to the Regional Superfund Ground Water Forum is the transport and fate of contaminants in soil and ground water as related to subsurface remediation. Processes which influence the behavior of contaminants in the subsurface must be considered bot...

PAVECHECK : training material updated user's manual including GPS.

DOT National Transportation Integrated Search

2009-01-01

PAVECHECK is a software package used to integrate nondestructive test data from various testing systems to provide the pavement engineer with a comprehensive evaluation of both surface and subsurface conditions. This User's Manual is intended to demo...

Approaching a universal scaling relationship between fracture stiffness and fluid flow

NASA Astrophysics Data System (ADS)

Pyrak-Nolte, Laura J.; Nolte, David D.

2016-02-01

A goal of subsurface geophysical monitoring is the detection and characterization of fracture alterations that affect the hydraulic integrity of a site. Achievement of this goal requires a link between the mechanical and hydraulic properties of a fracture. Here we present a scaling relationship between fluid flow and fracture-specific stiffness that approaches universality. Fracture-specific stiffness is a mechanical property dependent on fracture geometry that can be monitored remotely using seismic techniques. A Monte Carlo numerical approach demonstrates that a scaling relationship exists between flow and stiffness for fractures with strongly correlated aperture distributions, and continues to hold for fractures deformed by applied stress and by chemical erosion as well. This new scaling relationship provides a foundation for simulating changes in fracture behaviour as a function of stress or depth in the Earth and will aid risk assessment of the hydraulic integrity of subsurface sites.

Implementing a conceptual model of physical and chemical soil profile evolution

NASA Astrophysics Data System (ADS)

Kirkby, Mike

2017-04-01

When soil profile composition is generalised in terms of the proportion, p, of bedrock remaining (= 1 - depletion ratio), then other soil processes can also be expressed in terms of p, and 'soil depth' described by the integral of (1-p) down to bedrock. Soil profile evolution is expressed as the advance of a sigmoidal weathering front into the critical zone under the action of upward ionic diffusion of weathering products; downward advection of solutes in percolating waters, with loss of (cleanish) water as evapotranspiration and (solute-laden) water as a lateral sub-surface flow increment; and mechanical denudation increment at the surface. Each component responds to the degree of weathering. Percolation is limited by precipitation, evapotranspiration demand and the degree of weathering at each level in the profile which diverts subsurface flow. Mechanical removal rates are considered to broadly increase as weathering proceeds, as grain size and dilation angle decreases. The implication of these assumptions can be examined for steady state profiles, for which observed relationships between mechanical and chemical denudation rates; and between chemical denudation and critical zone depth are reproduced. For non-steady state evolution, these relationships break down, but provide a basis for linking critical zone with hillslope/ landform evolution.

Comparison of simple, small, full-scale sewage treatment systems in Brazil: UASB-maturation ponds-coarse filter; UASB-horizontal subsurface-flow wetland; vertical-flow wetland (first stage of French system).

PubMed

von Sperling, M

2015-01-01

This paper presents a comparison between three simple sewage treatment lines involving natural processes: (a) upflow anaerobic sludge blanket (UASB) reactor-three maturation ponds in series-coarse rock filter; (b) UASB reactor-horizontal subsurface-flow constructed wetland; and (c) vertical-flow constructed wetlands treating raw sewage (first stage of the French system). The evaluation was based on several years of practical experience with three small full-scale plants receiving the same influent wastewater (population equivalents of 220, 60 and 100 inhabitants) in the city of Belo Horizonte, Brazil. The comparison included interpretation of concentrations and removal efficiencies based on monitoring data (organic matter, solids, nitrogen, phosphorus, coliforms and helminth eggs), together with an evaluation of practical aspects, such as land and volume requirements, sludge production and handling, plant management, clogging and others. Based on an integrated evaluation of all aspects involved, it is worth emphasizing that each system has its own specificities, and no generalization can be made on the best option. The overall conclusion is that the three lines are suitable for sewage treatment in small communities in warm-climate regions.

Contaminated environments in the subsurface and bioremediation: organic contaminants.

PubMed

Holliger, C; Gaspard, S; Glod, G; Heijman, C; Schumacher, W; Schwarzenbach, R P; Vazquez, F

1997-07-01

Due to leakages, spills, improper disposal and accidents during transport, organic compounds have become subsurface contaminants that threaten important drinking water resources. One strategy to remediate such polluted subsurface environments is to make use of the degradative capacity of bacteria. It is often sufficient to supply the subsurface with nutrients such as nitrogen and phosphorus, and aerobic treatments are still dominating. However, anaerobic processes have advantages such as low biomass production and good electron acceptor availability, and they are sometimes the only possible solution. This review will focus on three important groups of environmental organic contaminants: hydrocarbons, chlorinated and nitroaromatic compounds. Whereas hydrocarbons are oxidized and completely mineralized under anaerobic conditions in the presence of electron acceptors such as nitrate, iron, sulfate and carbon dioxide, chlorinated and nitroaromatic compounds are reductively transformed. For the aerobic often persistent polychlorinated compounds, reductive dechlorination leads to harmless products or to compounds that are aerobically degradable. The nitroaromatic compounds are first reductively transformed to the corresponding amines and can subsequently be bound to the humic fraction in an aerobic process. Such new findings and developments give hope that in the near future contaminated aquifers can efficiently be remediated, a prerequisite for a sustainable use of the precious-subsurface drinking water resources.

Modeling Phosphorus Losses through Surface Runoff and Subsurface Drainage Using ICECREAM.

PubMed

Qi, Hongkai; Qi, Zhiming; Zhang, T Q; Tan, C S; Sadhukhan, Debasis

2018-03-01

Modeling soil phosphorus (P) losses by surface and subsurface flow pathways is essential in developing successful strategies for P pollution control. We used the ICECREAM model to simultaneously simulate P losses in surface and subsurface flow, as well as to assess effectiveness of field practices in reducing P losses. Monitoring data from a mineral-P-fertilized clay loam field in southwestern Ontario, Canada, were used for calibration and validation. After careful adjustment of model parameters, ICECREAM was shown to satisfactorily simulate all major processes of surface and subsurface P losses. When the calibrated model was used to assess tillage and fertilizer management scenarios, results point to a 10% reduction in total P losses by shifting autumn tillage to spring, and a 25.4% reduction in total P losses by injecting fertilizer rather than broadcasting. Although the ICECREAM model was effective in simulating surface and subsurface P losses when thoroughly calibrated, further testing is needed to confirm these results with manure P application. As illustrated here, successful use of simulation models requires careful verification of model routines and comprehensive calibration to ensure that site-specific processes are accurately represented. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Microbial redox processes in deep subsurface environments and the potential application of (per)chlorate in oil reservoirs

PubMed Central

Liebensteiner, Martin G.; Tsesmetzis, Nicolas; Stams, Alfons J. M.; Lomans, Bartholomeus P.

2014-01-01

The ability of microorganisms to thrive under oxygen-free conditions in subsurface environments relies on the enzymatic reduction of oxidized elements, such as sulfate, ferric iron, or CO2, coupled to the oxidation of inorganic or organic compounds. A broad phylogenetic and functional diversity of microorganisms from subsurface environments has been described using isolation-based and advanced molecular ecological techniques. The physiological groups reviewed here comprise iron-, manganese-, and nitrate-reducing microorganisms. In the context of recent findings also the potential of chlorate and perchlorate [jointly termed (per)chlorate] reduction in oil reservoirs will be discussed. Special attention is given to elevated temperatures that are predominant in the deep subsurface. Microbial reduction of (per)chlorate is a thermodynamically favorable redox process, also at high temperature. However, knowledge about (per)chlorate reduction at elevated temperatures is still scarce and restricted to members of the Firmicutes and the archaeon Archaeoglobus fulgidus. By analyzing the diversity and phylogenetic distribution of functional genes in (meta)genome databases and combining this knowledge with extrapolations to earlier-made physiological observations we speculate on the potential of (per)chlorate reduction in the subsurface and more precisely oil fields. In addition, the application of (per)chlorate for bioremediation, souring control, and microbial enhanced oil recovery are addressed. PMID:25225493

Uranium Biomineralization By Natural Microbial Phosphatase Activities in the Subsurface

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

Taillefert, Martial

This project investigated the geochemical and microbial processes associated with the biomineralization of radionuclides in subsurface soils. During this study, it was determined that microbial communities from the Oak Ridge Field Research subsurface are able to express phosphatase activities that hydrolyze exogenous organophosphate compounds and result in the non-reductive bioimmobilization of U(VI) phosphate minerals in both aerobic and anaerobic conditions. The changes of the microbial community structure associated with the biomineralization of U(VI) was determined to identify the main organisms involved in the biomineralization process, and the complete genome of two isolates was sequenced. In addition, it was determined thatmore » both phytate, the main source of natural organophosphate compounds in natural environments, and polyphosphate accumulated in cells could also be hydrolyzed by native microbial population to liberate enough orthophosphate and precipitate uranium phosphate minerals. Finally, the minerals produced during this process are stable in low pH conditions or environments where the production of dissolved inorganic carbon is moderate. These findings suggest that the biomineralization of U(VI) phosphate minerals is an attractive bioremediation strategy to uranium bioreduction in low pH uranium-contaminated environments. These efforts support the goals of the SBR long-term performance measure by providing key information on "biological processes influencing the form and mobility of DOE contaminants in the subsurface".« less

Rescuing the Cahoon Mine drill cores: Opportunities for modern mapping of the ca. 1.7 Ga Freedom Formation in southern Wisconsin

NASA Astrophysics Data System (ADS)

Stanley, V.; Stewart, E.

2016-12-01

Rock cores collected during historic mineral exploration can provide invaluable data for modern analyses, but only if the samples are properly curated. The Cahoon Mine operated in Baraboo, WI during the 1910's and produced iron ore from the ca. 1.7 Ga Freedom Formation. The Freedom Formation is part of the well-known Baraboo-interval stratigraphy and is only present in the subsurface of Wisconsin (Weidman, 1904). Seventeen exploratory drill cores were rescued by Wisconsin Geological and Natural History Survey (WGNHS) from the original drying house at the mine site. The condition of the containers endangered the stratigraphic context of the collection; identifiers and depth markings were often obscured or lost. The individual core pieces were coated in residue and dust. Most of what is known about the Freedom Formation is from core logs and master's theses from the early 1900's (Leith, 1935; Schmidt, 1951). Ongoing subsurface mapping of the Baraboo-interval sediments and underlying basement of southern Wisconsin integrates new and existing subsurface and regional geophysical datasets. Mapping involves calibrating unique signals in regional aeromagnetic data to known lithology from drill core and cuttings. The Freedom Formation is especially important in this process as its iron-rich composition and regional continuity causes it to have a somewhat unique signal in regional aeromagnetic data. The Cahoon Mine cores in the WGNHS repository are the most extensive collection of physical samples from the Freedom Formation still in existence. We are in the process of curating the cores to facilitate their use in ongoing bedrock mapping. Today the cost and logistics of extensive sampling of this unit makes the existing core collection irreplaceable. We transferred the material to new containers, digitally recorded metadata, and created archival labels. As a result of this effort, the Cahoon Mine cores are now stored in a format that is physically and digitally accessible.

Epidermal segmentation in high-definition optical coherence tomography.

PubMed

Li, Annan; Cheng, Jun; Yow, Ai Ping; Wall, Carolin; Wong, Damon Wing Kee; Tey, Hong Liang; Liu, Jiang

2015-01-01

Epidermis segmentation is a crucial step in many dermatological applications. Recently, high-definition optical coherence tomography (HD-OCT) has been developed and applied to imaging subsurface skin tissues. In this paper, a novel epidermis segmentation method using HD-OCT is proposed in which the epidermis is segmented by 3 steps: the weighted least square-based pre-processing, the graph-based skin surface detection and the local integral projection-based dermal-epidermal junction detection respectively. Using a dataset of five 3D volumes, we found that this method correlates well with the conventional method of manually marking out the epidermis. This method can therefore serve to effectively and rapidly delineate the epidermis for study and clinical management of skin diseases.

MA_MISS and terrestrial analogues for Mars

NASA Astrophysics Data System (ADS)

De Sanctis, M. C.; De Angelis, S.; Ammannito, E.; Di Iorio, T.; Carli, C.; Frigeri, A.; Boccaccini, A.; Battistelli, E.; Mugnolo, R.; MA MISS Team

2012-09-01

The MA_MISS instrument (Mars Multispectral Imager for Subsurface Studies) is a VIS-NIR spectrometer devoted to study the Martian subsoil within the ExoMars mission. This miniaturized spectrometer is integrated in drilling system of the ExoMars Pasteur Rover, and will investigate the Martian subsoil down to 2 m, in the spectral range 0.4 - 2.2 μm [1,2]. It will provide important information regarding the composition and mineralogy of the Martian subsoil, whose materials are expected to be less altered by erosion and other exogenous processes than surface rocks. With a view to doing laboratory spectroscopic measurements with the instrument breadboard, we performed preliminary laboratory measurements on Mars analogues using a spectrophotometer coupled with a goniometer.

A design study for a medium-scale field demonstration of the viscous barrier technology

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

Moridis, G.; Yen, P.; Persoff, P.

1996-09-01

This report is the design study for a medium-scale field demonstration of Lawrence Berkeley National Laboratory`s new subsurface containment technology for waste isolation using a new generation of barrier liquids. The test site is located in central California in a quarry owned by the Los Banos Gravel Company in Los Banos, California, in heterogeneous unsaturated deposits of sand, silt, and -ravel typical of many of the and DOE cleanup sites and particularly analogous to the Hanford site. The coals of the field demonstration are (a) to demonstrate the ability to create a continuous subsurface barrier isolating a medium-scale volume (30more » ft long by 30 ft wide by 20 ft deep, i.e. 1/10th to 1/8th the size of a buried tank at the Hanford Reservation) in the subsurface, and (b) to demonstrate the continuity, performance, and integrity of the barrier.« less

Advanced core-analyses for subsurface characterization

NASA Astrophysics Data System (ADS)

Pini, R.

2017-12-01

The heterogeneity of geological formations varies over a wide range of length scales and represents a major challenge for predicting the movement of fluids in the subsurface. Although they are inherently limited in the accessible length-scale, laboratory measurements on reservoir core samples still represent the only way to make direct observations on key transport properties. Yet, properties derived on these samples are of limited use and should be regarded as sample-specific (or `pseudos'), if the presence of sub-core scale heterogeneities is not accounted for in data processing and interpretation. The advent of imaging technology has significantly reshaped the landscape of so-called Special Core Analysis (SCAL) by providing unprecedented insight on rock structure and processes down to the scale of a single pore throat (i.e. the scale at which all reservoir processes operate). Accordingly, improved laboratory workflows are needed that make use of such wealth of information by e.g., referring to the internal structure of the sample and in-situ observations, to obtain accurate parameterisation of both rock- and flow-properties that can be used to populate numerical models. We report here on the development of such workflow for the study of solute mixing and dispersion during single- and multi-phase flows in heterogeneous porous systems through a unique combination of two complementary imaging techniques, namely X-ray Computed Tomography (CT) and Positron Emission Tomography (PET). The experimental protocol is applied to both synthetic and natural porous media, and it integrates (i) macroscopic observations (tracer effluent curves), (ii) sub-core scale parameterisation of rock heterogeneities (e.g., porosity, permeability and capillary pressure), and direct 3D observation of (iii) fluid saturation distribution and (iv) the dynamic spreading of the solute plumes. Suitable mathematical models are applied to reproduce experimental observations, including both 1D and 3D numerical schemes populated with the parameterisation above. While it validates the core-flooding experiments themselves, the calibrated mathematical model represents a key element for extending them to conditions prevalent in the subsurface, which would be otherwise not attainable in the laboratory.

Improving Permafrost Hydrology Prediction Through Data-Model Integration

NASA Astrophysics Data System (ADS)

Wilson, C. J.; Andresen, C. G.; Atchley, A. L.; Bolton, W. R.; Busey, R.; Coon, E.; Charsley-Groffman, L.

2017-12-01

The CMIP5 Earth System Models were unable to adequately predict the fate of the 16GT of permafrost carbon in a warming climate due to poor representation of Arctic ecosystem processes. The DOE Office of Science Next Generation Ecosystem Experiment, NGEE-Arctic project aims to reduce uncertainty in the Arctic carbon cycle and its impact on the Earth's climate system by improved representation of the coupled physical, chemical and biological processes that drive how much buried carbon will be converted to CO2 and CH4, how fast this will happen, which form will dominate, and the degree to which increased plant productivity will offset increased soil carbon emissions. These processes fundamentally depend on permafrost thaw rate and its influence on surface and subsurface hydrology through thermal erosion, land subsidence and changes to groundwater flow pathways as soil, bedrock and alluvial pore ice and massive ground ice melts. LANL and its NGEE colleagues are co-developing data and models to better understand controls on permafrost degradation and improve prediction of the evolution of permafrost and its impact on Arctic hydrology. The LANL Advanced Terrestrial Simulator was built using a state of the art HPC software framework to enable the first fully coupled 3-dimensional surface-subsurface thermal-hydrology and land surface deformation simulations to simulate the evolution of the physical Arctic environment. Here we show how field data including hydrology, snow, vegetation, geochemistry and soil properties, are informing the development and application of the ATS to improve understanding of controls on permafrost stability and permafrost hydrology. The ATS is being used to inform parameterizations of complex coupled physical, ecological and biogeochemical processes for implementation in the DOE ACME land model, to better predict the role of changing Arctic hydrology on the global climate system. LA-UR-17-26566.

Conceptual Model of Iodine Behavior in the Subsurface at the Hanford Site

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

Truex, Michael J.; Lee, Brady D.; Johnson, Christian D.

The fate and transport of 129I in the environment and potential remediation technologies are currently being studied as part of environmental remediation activities at the Hanford Site. A conceptual model describing the nature and extent of subsurface contamination, factors that control plume behavior, and factors relevant to potential remediation processes is needed to support environmental remedy decisions. Because 129I is an uncommon contaminant, relevant remediation experience and scientific literature are limited. Thus, the conceptual model also needs to both describe known contaminant and biogeochemical process information and to identify aspects about which additional information needed to effectively support remedy decisions.more » this document summarizes the conceptual model of iodine behavior relevant to iodine in the subsurface environment at the Hanford site.« less

Towards a geophysical decision-support system for monitoring and managing unstable slopes

NASA Astrophysics Data System (ADS)

Chambers, J. E.; Meldrum, P.; Wilkinson, P. B.; Uhlemann, S.; Swift, R. T.; Inauen, C.; Gunn, D.; Kuras, O.; Whiteley, J.; Kendall, J. M.

2017-12-01

Conventional approaches for condition monitoring, such as walk over surveys, remote sensing or intrusive sampling, are often inadequate for predicting instabilities in natural and engineered slopes. Surface observations cannot detect the subsurface precursors to failure events; instead they can only identify failure once it has begun. On the other hand, intrusive investigations using boreholes only sample a very small volume of ground and hence small scale deterioration process in heterogeneous ground conditions can easily be missed. It is increasingly being recognised that geophysical techniques can complement conventional approaches by providing spatial subsurface information. Here we describe the development and testing of a new geophysical slope monitoring system. It is built around low-cost electrical resistivity tomography instrumentation, combined with integrated geotechnical logging capability, and coupled with data telemetry. An automated data processing and analysis workflow is being developed to streamline information delivery. The development of this approach has provided the basis of a decision-support tool for monitoring and managing unstable slopes. The hardware component of the system has been operational at a number of field sites associated with a range of natural and engineered slopes for up to two years. We report on the monitoring results from these sites, discuss the practicalities of installing and maintaining long-term geophysical monitoring infrastructure, and consider the requirements of a fully automated data processing and analysis workflow. We propose that the result of this development work is a practical decision-support tool that can provide near-real-time information relating to the internal condition of problematic slopes.

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.

Anthropogenic effects on the subsurface thermal and groundwater environments in Osaka, Japan and Bangkok, Thailand.

PubMed

Taniguchi, Makoto; Shimada, Jun; Fukuda, Yoichi; Yamano, Makoto; Onodera, Shin-ichi; Kaneko, Shinji; Yoshikoshi, Akihisa

2009-04-15

Anthropogenic effects in both Osaka and Bangkok were evaluated to compare the relationships between subsurface environment and the development stage of both cities. Subsurface thermal anomalies due to heat island effects were found in both cities. The Surface Warming Index (SWI), the departure depth from the steady geothermal gradient, was used as an indicator of the heat island effect. SWI increases (deeper) with the magnitude of heat island effect and the elapsed time starting from the surface warming. Distributions of subsurface thermal anomalies due to the heat island effect agreed well with the distribution of changes in air temperature due to the same process, which is described by the distribution of population density in both Osaka and Bangkok. Different time lags between groundwater depression and subsidence in the two cities was found. This is attributed to differences in hydrogeologic characters, such as porosity and hydraulic conductivity. We find that differences in subsurface degradations in Osaka and Bangkok, including subsurface thermal anomalies, groundwater depression, and land subsidence, depends on the difference of the development stage of urbanization and hydrogeological characters.

SeSBench - An initiative to benchmark reactive transport models for environmental subsurface processes

NASA Astrophysics Data System (ADS)

Jacques, Diederik

2017-04-01

As soil functions are governed by a multitude of interacting hydrological, geochemical and biological processes, simulation tools coupling mathematical models for interacting processes are needed. Coupled reactive transport models are a typical example of such coupled tools mainly focusing on hydrological and geochemical coupling (see e.g. Steefel et al., 2015). Mathematical and numerical complexity for both the tool itself or of the specific conceptual model can increase rapidly. Therefore, numerical verification of such type of models is a prerequisite for guaranteeing reliability and confidence and qualifying simulation tools and approaches for any further model application. In 2011, a first SeSBench -Subsurface Environmental Simulation Benchmarking- workshop was held in Berkeley (USA) followed by four other ones. The objective is to benchmark subsurface environmental simulation models and methods with a current focus on reactive transport processes. The final outcome was a special issue in Computational Geosciences (2015, issue 3 - Reactive transport benchmarks for subsurface environmental simulation) with a collection of 11 benchmarks. Benchmarks, proposed by the participants of the workshops, should be relevant for environmental or geo-engineering applications; the latter were mostly related to radioactive waste disposal issues - excluding benchmarks defined for pure mathematical reasons. Another important feature is the tiered approach within a benchmark with the definition of a single principle problem and different sub problems. The latter typically benchmarked individual or simplified processes (e.g. inert solute transport, simplified geochemical conceptual model) or geometries (e.g. batch or one-dimensional, homogeneous). Finally, three codes should be involved into a benchmark. The SeSBench initiative contributes to confidence building for applying reactive transport codes. Furthermore, it illustrates the use of those type of models for different environmental and geo-engineering applications. SeSBench will organize new workshops to add new benchmarks in a new special issue. Steefel, C. I., et al. (2015). "Reactive transport codes for subsurface environmental simulation." Computational Geosciences 19: 445-478.

In-situ Planetary Subsurface Imaging System

NASA Astrophysics Data System (ADS)

Song, W.; Weber, R. C.; Dimech, J. L.; Kedar, S.; Neal, C. R.; Siegler, M.

2017-12-01

Geophysical and seismic instruments are considered the most effective tools for studying the detailed global structures of planetary interiors. A planet's interior bears the geochemical markers of its evolutionary history, as well as its present state of activity, which has direct implications to habitability. On Earth, subsurface imaging often involves massive data collection from hundreds to thousands of geophysical sensors (seismic, acoustic, etc) followed by transfer by hard links or wirelessly to a central location for post processing and computing, which will not be possible in planetary environments due to imposed mission constraints on mass, power, and bandwidth. Emerging opportunities for geophysical exploration of the solar system from Venus to the icy Ocean Worlds of Jupiter and Saturn dictate that subsurface imaging of the deep interior will require substantial data reduction and processing in-situ. The Real-time In-situ Subsurface Imaging (RISI) technology is a mesh network that senses and processes geophysical signals. Instead of data collection then post processing, the mesh network performs the distributed data processing and computing in-situ, and generates an evolving 3D subsurface image in real-time that can be transmitted under bandwidth and resource constraints. Seismic imaging algorithms (including traveltime tomography, ambient noise imaging, and microseismic imaging) have been successfully developed and validated using both synthetic and real-world terrestrial seismic data sets. The prototype hardware system has been implemented and can be extended as a general field instrumentation platform tailored specifically for a wide variety of planetary uses, including crustal mapping, ice and ocean structure, and geothermal systems. The team is applying the RISI technology to real off-world seismic datasets. For example, the Lunar Seismic Profiling Experiment (LSPE) deployed during the Apollo 17 Moon mission consisted of four geophone instruments spaced up to 100 meters apart, which in essence forms a small aperture seismic network. A pattern recognition technique based on Hidden Markov Models was able to characterize this dataset, and we are exploring how the RISI technology can be adapted for this dataset.

Separation of toxic metal ions, hydrophilic hydrocarbons, hydrophobic fuel and halogenated hydrocarbons and recovery of ethanol from a process stream

DOEpatents

Kansa, Edward J.; Anderson, Brian L.; Wijesinghe, Ananda M.; Viani, Brian E.

1999-01-01

This invention provides a process to tremendously reduce the bulk volume of contaminants obtained from an effluent stream produced subsurface remediation. The chemicals used for the subsurface remediation are reclaimed for recycling to the remediation process. Additional reductions in contaminant bulk volume are achieved by the ultra-violet light destruction of halogenated hydrocarbons, and the complete oxidation of hydrophobic fuel hydrocarbons and hydrophilic hydrocarbons. The contaminated bulk volume will arise primarily from the disposal of the toxic metal ions. The entire process is modular, so if there are any technological breakthroughs in one or more of the component process modules, such modules can be readily replaced.

Effects of rainfall patterns and land cover on the subsurface flow generation of sloping Ferralsols in southern China

PubMed Central

Yang, Jie; Tang, Chongjun; Chen, Lihua; Liu, Yaojun; Wang, Lingyun

2017-01-01

Rainfall patterns and land cover are two important factors that affect the runoff generation process. To determine the surface and subsurface flows associated with different rainfall patterns on sloping Ferralsols under different land cover types, observational data related to surface and subsurface flows from 5 m × 15 m plots were collected from 2010 to 2012. The experiment was conducted to assess three land cover types (grass, litter cover and bare land) in the Jiangxi Provincial Soil and Water Conservation Ecological Park. During the study period, 114 natural rainfall events produced subsurface flow and were divided into four groups using k-means clustering according to rainfall duration, rainfall depth and maximum 30-min rainfall intensity. The results showed that the total runoff and surface flow values were highest for bare land under all four rainfall patterns and lowest for the covered plots. However, covered plots generated higher subsurface flow values than bare land. Moreover, the surface and subsurface flows associated with the three land cover types differed significantly under different rainfall patterns. Rainfall patterns with low intensities and long durations created more subsurface flow in the grass and litter cover types, whereas rainfall patterns with high intensities and short durations resulted in greater surface flow over bare land. Rainfall pattern I had the highest surface and subsurface flow values for the grass cover and litter cover types. The highest surface flow value and lowest subsurface flow value for bare land occurred under rainfall pattern IV. Rainfall pattern II generated the highest subsurface flow value for bare land. Therefore, grass or litter cover are able to convert more surface flow into subsurface flow under different rainfall patterns. The rainfall patterns studied had greater effects on subsurface flow than on total runoff and surface flow for covered surfaces, as well as a greater effect on surface flows associated with bare land. PMID:28792507

Denitrifying Bacteria from the Genus Rhodanobacter Dominate Bacterial Communities in the Highly Contaminated Subsurface of a Nuclear Legacy Waste Site

PubMed Central

Green, Stefan J.; Prakash, Om; Jasrotia, Puja; Overholt, Will A.; Cardenas, Erick; Hubbard, Daniela; Tiedje, James M.; Watson, David B.; Schadt, Christopher W.; Brooks, Scott C.

2012-01-01

The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface was investigated at the field scale at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN. The abundance, community composition, and distribution of groundwater microorganisms were examined across the site during two seasonal sampling events. At representative locations, subsurface sediment was also examined from two boreholes, one sampled from the most heavily contaminated area of the site and another from an area with low contamination. A suite of DNA- and RNA-based molecular tools were employed for community characterization, including quantitative PCR of rRNA and nitrite reductase genes, community composition fingerprinting analysis, and high-throughput pyrotag sequencing of rRNA genes. The results demonstrate that pH is a major driver of the subsurface microbial community structure and that denitrifying bacteria from the genus Rhodanobacter (class Gammaproteobacteria) dominate at low pH. The relative abundance of bacteria from this genus was positively correlated with lower-pH conditions, and these bacteria were abundant and active in the most highly contaminated areas. Other factors, such as the concentration of nitrogen species, oxygen level, and sampling season, did not appear to strongly influence the distribution of Rhodanobacter bacteria. The results indicate that these organisms are acid-tolerant denitrifiers, well suited to the acidic, nitrate-rich subsurface conditions, and pH is confirmed as a dominant driver of bacterial community structure in this contaminated subsurface environment. PMID:22179233

Remote sensing for environmental protection of the eastern Mediterranean rugged mountainous areas, Lebanon

NASA Astrophysics Data System (ADS)

Khawlie, M.; Awad, M.; Shaban, A.; Bou Kheir, R.; Abdallah, C.

Lying along the eastern Mediterranean coast with elevated mountain chains higher than 2500 m straddling its terrain, Lebanon is a country of natural beauty and is thus attracting tourism. However, with a population density exceeding 800/km 2 and a rugged steep sloping land, problems abound in the country calling for holistic-approach studies. Only remote sensing, whose use is new in Lebanon can secure such needed studies within a scientific and pragmatic framework. The paper demonstrates for the concerned themes, the innovative use of remote sensing in such a difficult terrain, giving three examples of major environmental problems in the coastal mountains. Only few studies have so far focused on those mountains, notably application of remote sensing. The rugged mountainous terrain receives considerable rain, but the water is quickly lost running on the steep slopes, or infiltrating through fractures and the karstic conduits into the subsurface. Field investigations are difficult to achieve, therefore, remote sensing helps reveal various surface land features important in reflecting water feeding into the subsurface. Optical, radar and thermal infrared remotely sensed data cover a wide spectrum serving that purpose. A map of preferential groundwater accumulation potential is produced. It can serve for better water exploitation as well as protection. Because the terrain is karstic and rugged, the subsurface water flow is difficult to discern. Any pollution at a certain spot would certainly spread around. This constitutes the second example of environmental problems facing the mountainous areas in Lebanon. An integrated approach using remote sensing and geographic information systems (GIS) gives good results in finding out the likelihood of how pollution, or contaminants, can selectively move in the subsurface. A diagnostic analysis with a GIS-type software acts as a guide producing indicative maps for the above purpose. The third example given deals with the problem of losing soil, which is a very vital source in such mountainous land. With steep slopes, torrential rain and improper human interference, run-off is high and water-soil erosion is continuously deteriorating the land cover. Remote sensing can facilitate studying the factors enhancing the process, such as soil type, slope gradient, drainage, geology and land cover. Digital elevation models created from SAR imagery contribute significantly to assessing vulnerability of hydric-soil erosion over such a difficult terrain. GIS layers of the above factors are integrated with erosional criteria to produce a risk map of soil erosion. Results indicate that 36% of the Lebanese terrain is under threat of high-level erosion, and 52% of that is concentrated in the rugged mountainous regions.

Blooms and subsurface phytoplankton layers on the Scotian Shelf: Insights from profiling gliders

NASA Astrophysics Data System (ADS)

Ross, Tetjana; Craig, Susanne E.; Comeau, Adam; Davis, Richard; Dever, Mathieu; Beck, Matthew

2017-08-01

Understanding how phytoplankton respond to their physical environment is key to predicting how bloom dynamics might change under future climate change scenarios. Phytoplankton are at the base of most marine food webs and play an important role in drawing CO2 out of the atmosphere. Using nearly 5 years of simultaneous CTD, irradiance, chlorophyll a fluorescence and optical backscattering observations obtained from Slocum glider missions, we observed the subsurface phytoplankton populations across the Scotian Shelf, near Halifax (Nova Scotia, Canada) along with their physical environment. Bloom conditions were observed in each of the 5 springs, with the average chlorophyll in the upper 60 m of water generally exceeding 3 mg m- 3. These blooms occurred when the upper water column stratification was at its lowest, in apparent contradiction of the critical depth hypothesis. A subsurface chlorophyll layer was observed each summer at about 30 m depth, which was below the base of the mixed layer. This subsurface layer lasted 3-4 months and contained, on average, 1/4 of the integrated water column chlorophyll found during the spring bloom. This suggests that a significant portion of the primary productivity over the Scotian Shelf occurs at depths that cannot be observed by satellites-highlighting the importance of including subsurface observations in the monitoring of future changes to primary productivity in the ocean.

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.

An oligotrophic deep-subsurface community dependent on syntrophy is dominated by sulfur-driven autotrophic denitrifiers

PubMed Central

Kieft, Thomas L.; Kuloyo, Olukayode; Linage-Alvarez, Borja; van Heerden, Esta; Lindsay, Melody R.; Magnabosco, Cara; Wang, Wei; Wiggins, Jessica B.; Guo, Ling; Perlman, David H.; Kyin, Saw; Shwe, Henry H.; Harris, Rachel L.; Oh, Youmi; Yi, Min Joo; Purtschert, Roland; Slater, Greg F.; Ono, Shuhei; Wei, Siwen; Li, Long; Sherwood Lollar, Barbara; Onstott, Tullis C.

2016-01-01

Subsurface lithoautotrophic microbial ecosystems (SLiMEs) under oligotrophic conditions are typically supported by H2. Methanogens and sulfate reducers, and the respective energy processes, are thought to be the dominant players and have been the research foci. Recent investigations showed that, in some deep, fluid-filled fractures in the Witwatersrand Basin, South Africa, methanogens contribute <5% of the total DNA and appear to produce sufficient CH4 to support the rest of the diverse community. This paradoxical situation reflects our lack of knowledge about the in situ metabolic diversity and the overall ecological trophic structure of SLiMEs. Here, we show the active metabolic processes and interactions in one of these communities by combining metatranscriptomic assemblies, metaproteomic and stable isotopic data, and thermodynamic modeling. Dominating the active community are four autotrophic β-proteobacterial genera that are capable of oxidizing sulfur by denitrification, a process that was previously unnoticed in the deep subsurface. They co-occur with sulfate reducers, anaerobic methane oxidizers, and methanogens, which each comprise <5% of the total community. Syntrophic interactions between these microbial groups remove thermodynamic bottlenecks and enable diverse metabolic reactions to occur under the oligotrophic conditions that dominate in the subsurface. The dominance of sulfur oxidizers is explained by the availability of electron donors and acceptors to these microorganisms and the ability of sulfur-oxidizing denitrifiers to gain energy through concomitant S and H2 oxidation. We demonstrate that SLiMEs support taxonomically and metabolically diverse microorganisms, which, through developing syntrophic partnerships, overcome thermodynamic barriers imposed by the environmental conditions in the deep subsurface. PMID:27872277

Polarimetric and Indoor Imaging Fusion Based on Compressive Sensing

DTIC Science & Technology

2013-04-01

Signal Process., vol. 57, no. 6, pp. 2275-2284, 2009. [20] A. Gurbuz, J. McClellan, and W. Scott, Jr., "Compressive sensing for subsurface imaging using...SciTech Publishing, 2010, pp. 922- 938. [45] A. C. Gurbuz, J. H. McClellan, and W. R. Scott, Jr., "Compressive sensing for subsurface imaging using

Chronology: An Important (and Potentially Accessible) Parameter in Understanding Europa Surface-Subsurface Material Interchange, Burial, and Resurfacing Processes

NASA Technical Reports Server (NTRS)

Swindle, T. D.

2001-01-01

Time is an important parameter in understanding the interaction of the surface and subsurface of Europa. It should be possible to determine potassium-argon and cosmic ray exposure ages in situ on the surface of Europa. Additional information is contained in the original extended abstract.

Uncertainty of simulated groundwater levels arising from stochastic transient climate change scenarios

NASA Astrophysics Data System (ADS)

Goderniaux, Pascal; Brouyère, Serge; Blenkinsop, Stephen; Burton, Aidan; Fowler, Hayley; Dassargues, Alain

2010-05-01

The evaluation of climate change impact on groundwater reserves represents a difficult task because both hydrological and climatic processes are complex and difficult to model. In this study, we present an innovative methodology that combines the use of integrated surface - subsurface hydrological models with advanced stochastic transient climate change scenarios. This methodology is applied to the Geer basin (480 km²) in Belgium, which is intensively exploited to supply the city of Liège (Belgium) with drinking water. The physically-based, spatially-distributed, surface-subsurface flow model has been developed with the finite element model HydroGeoSphere . The simultaneous solution of surface and subsurface flow equations in HydroGeoSphere, as well as the internal calculation of the actual evapotranspiration as a function of the soil moisture at each node of the evaporative zone, enables a better representation of interconnected processes in all domains of the catchment (fully saturated zone, partially saturated zone, surface). Additionally, the use of both surface and subsurface observed data to calibrate the model better constrains the calibration of the different water balance terms. Crucially, in the context of climate change impacts on groundwater resources, the evaluation of groundwater recharge is improved. . This surface-subsurface flow model is combined with advanced climate change scenarios for the Geer basin. Climate change simulations were obtained from six regional climate model (RCM) scenarios assuming the SRES A2 greenhouse gases emission (medium-high) scenario. These RCM scenarios were statistically downscaled using a transient stochastic weather generator technique, combining 'RainSim' and the 'CRU weather generator' for temperature and evapotranspiration time series. This downscaling technique exhibits three advantages compared with the 'delta change' method usually used in groundwater impact studies. (1) Corrections to climate model output are applied not only to the mean of climatic variables, but also across the statistical distributions of these variables. This is important as these distributions are expected to change in the future, with more extreme rainfall events, separated by longer dry periods. (2) The novel approach used in this study can simulate transient climate change from 2010 to 2085, rather than time series representative of a stationary climate for the period 2071-2100. (3) The weather generator is used to generate a large number of equiprobable climate change scenarios for each RCM, representative of the natural variability of the weather. All of these scenarios are applied as input to the Geer basin model to assess the projected impact of climate change on groundwater levels, the uncertainty arising for different RCM projections and the uncertainty linked to natural climatic variability. Using the output results from all scenarios, 95% confidence intervals are calculated for each year and month between 2010 and 2085. The climate change scenarios for the Geer basin model predict hotter and drier summers and warmer and wetter winters. Considering the results of this study, it is very likely that groundwater levels and surface flow rates in the Geer basin will decrease by the end of the century. This is of concern because it also means that groundwater quantities available for abstraction will also decrease. However, this study also shows that the uncertainty of these projections is relatively large compared to the projected changes so that it remains difficult to confidently determine the magnitude of the decrease. The use and combination of an integrated surface - subsurface model and stochastic climate change scenarios has never been used in previous climate change impact studies on groundwater resources. It constitutes an innovation and is an important tool for helping water managers to take decisions.

Subsurface damage distribution in the lapping process.

PubMed

Wang, Zhuo; Wu, Yulie; Dai, Yifan; Li, Shengyi

2008-04-01

To systematically investigate the influence of lapping parameters on subsurface damage (SSD) depth and characterize the damage feature comprehensively, maximum depth and distribution of SSD generated in the optical lapping process were measured with the magnetorheological finishing wedge technique. Then, an interaction of adjacent indentations was applied to interpret the generation of maximum depth of SSD. Eventually, the lapping procedure based on the influence of lapping parameters on the material removal rate and SSD depth was proposed to improve the lapping efficiency.

Terrestrial rock glaciers: a potential analog for Martian lobate flow features (LFF)

NASA Astrophysics Data System (ADS)

Sinha, Rishitosh K.; Vijayan, Sivaprahasam; Bharti, Rajiv R.

2016-05-01

Rock glaciers, regarded as cryospheric ice/water resource in the terrestrial-glacial systems based on their tongue/lobate-shaped flow characteristic and subsurface investigation using ground-penetrating radar. We examined the subsurface, geomorphology, climate-sensitivity and thermophysical properties of a Lobate Flow Feature (LFF) on Mars (30°-60° N and S hemispheres) to compare/assess the potentials of rock glaciers as an analog in suggesting LFFs to be a source of subsurface ice/water. LFFs are generally observed at the foot of impact craters' wall. HiRISE/CTX imageries from MRO spacecraft were used for geomorphological investigation of LFF using ArcMap-10.0 and subsurface investigation was carried out using data from MRO-SHARAD (shallow radar) after integrating with SiesWare-8.0. ENVI-5.0 was used to retrieve thermophysical properties of LFF from nighttime datasets (12.57 μm) acquired by THEMIS instrument-onboard the Mars Odyssey spacecraft and derive LFFs morphometry from MOLA altimeter point tracks onboard MGS spacecraft. Integrating crater chronology tool (Craterstats) with Arc Map, we have derived the formation age of LFF. Our investigation and comparison of LFF to rock glaciers revealed: (1) LFFs have preserved ice at depth 50m as revealed from SHARAD radargram and top-layer composed of rocky-debris material with thermal inertia ( 300-350 Jm-2 K-1s-1/2). (2) LFF formation age ( 10-100 Ma) corresponds to moderate scale debris covered glaciation of a shorter-span suggesting high sensitivity to obliquity-driven climatic shifts. (3) Presence of polygon cracks and high linear-arcuate furrow-and-ridges on the surface indicates presence of buried ice. This work is a significant step towards suggesting LFF to be a potential source of present-day stored ice/water on Mars.

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.

Forward modeling to investigate inversion artifacts resulting from time-lapse electrical resistivity tomography during rainfall simulations

NASA Astrophysics Data System (ADS)

Carey, Austin M.; Paige, Ginger B.; Carr, Bradley J.; Dogan, Mine

2017-10-01

Time-lapse electrical resistivity tomography (ERT) is commonly used as a minimally invasive tool to study infiltration processes. In 2014, we conducted field studies coupling variable intensity rainfall simulation with high-resolution ERT to study the real-time partitioning of rainfall into surface and subsurface response. The significant contrast in resistivity in the subsurface from large changes in subsurface moisture resulted in artifacts during the inversion process of the time-lapse ERT data collected using a dipole-dipole electrode array. These artifacts, which are not representative of real subsurface moisture dynamics, have been shown to arise during time-lapse inversion of ERT data and may be subject to misinterpretation. Forward modeling of the infiltration process post field experiments using a two-layer system (saprolite overlain by a soil layer) was used to generate synthetic datasets. The synthetic data were used to investigate the influence of both changes in volumetric moisture content and electrode configuration on the development of the artifacts identified in the field datasets. For the dipole-dipole array, we found that a decrease in the resistivity of the bottom layer by 67% resulted in a 50% reduction in artifact development. Artifacts for the seven additional array configurations tested, ranged from a 19% increase in artifact development (using an extended dipole-dipole array) to as much as a 96% decrease in artifact development (using a wenner-alpha array), compared to that of the dipole-dipole array. Moreover, these arrays varied in their ability to accurately delineate the infiltration front. Model results showed that the modified pole-dipole array was able to accurately image the infiltration zone and presented fewer artifacts for our experiments. In this study, we identify an optimal array type for imaging rainfall-infiltration dynamics that reduces artifacts. The influence of moisture contrast between the infiltrating water and the bulk subsurface material was characterized and shown to be a major factor in contributing to artifact development. Through forward modeling, this study highlights the importance of considering array type and subsurface moisture conditions when using time-lapse resistivity to obtain reliable estimates of vadose zone flow processes during rainfall-infiltration events.

Hierarchical Bayesian method for mapping biogeochemical hot spots using induced polarization imaging

DOE PAGES

Wainwright, Haruko M.; Flores Orozco, Adrian; Bucker, Matthias; ...

2016-01-29

In floodplain environments, a naturally reduced zone (NRZ) is considered to be a common biogeochemical hot spot, having distinct microbial and geochemical characteristics. Although important for understanding their role in mediating floodplain biogeochemical processes, mapping the subsurface distribution of NRZs over the dimensions of a floodplain is challenging, as conventional wellbore data are typically spatially limited and the distribution of NRZs is heterogeneous. In this work, we present an innovative methodology for the probabilistic mapping of NRZs within a three-dimensional (3-D) subsurface domain using induced polarization imaging, which is a noninvasive geophysical technique. Measurements consist of surface geophysical surveys andmore » drilling-recovered sediments at the U.S. Department of Energy field site near Rifle, CO (USA). Inversion of surface time domain-induced polarization (TDIP) data yielded 3-D images of the complex electrical resistivity, in terms of magnitude and phase, which are associated with mineral precipitation and other lithological properties. By extracting the TDIP data values colocated with wellbore lithological logs, we found that the NRZs have a different distribution of resistivity and polarization from the other aquifer sediments. To estimate the spatial distribution of NRZs, we developed a Bayesian hierarchical model to integrate the geophysical and wellbore data. In addition, the resistivity images were used to estimate hydrostratigraphic interfaces under the floodplain. Validation results showed that the integration of electrical imaging and wellbore data using a Bayesian hierarchical model was capable of mapping spatially heterogeneous interfaces and NRZ distributions thereby providing a minimally invasive means to parameterize a hydrobiogeochemical model of the floodplain.« less

Integrated interpretation of geophysical data of the Paleozoic structure in the northwestern part of the Siljan Ring impact crater, central Sweden

NASA Astrophysics Data System (ADS)

Muhamad, Harbe; Juhlin, Christopher; Malehmir, Alireza; Sopher, Daniel

2018-01-01

The Siljan Ring impact structure is the largest known impact structure in Europe and is Late Devonian in age. It contains a central uplift that is about 20-30 km in diameter and is surrounded by a ring-shaped depression. The Siljan area is one of the few areas in Sweden where the Paleozoic sequence has not been completely eroded, making it an important location for investigation of the geological and tectonic history of Baltica during the Paleozoic. The Paleozoic strata in this area also provide insight into the complex deformation processes associated with the impact. In this study we focus on the northwestern part of the Siljan Ring, close to the town of Orsa, with the main objective of characterizing the subsurface Paleozoic succession and uppermost Precambrian crystalline rocks along a series of seismic reflection profiles, some of which have not previously been published. We combine these seismic data with gravity and magnetic data and seismic traveltime tomography results to produce an integrated interpretation of the subsurface in the area. Our interpretation shows that the Paleozoic sequence in this area is of a relatively constant thickness, with a total thickness typically between 300 and 500 m. Faulting appears to be predominantly extensional, which we interpret to have occurred during the modification stage of the impact. Furthermore, based on the geophysical data in this area, we interpret that the impact related deformation to differ in magnitude and style from other parts of the Siljan Ring.

Observation to Theory in Deep Subsurface Microbiology Research: Can We Piece It Together?

NASA Astrophysics Data System (ADS)

Colwell, F. S.; Thurber, A. R.

2016-12-01

Three decades of observations of microbes in deep environments have led to startling discoveries of life in the subsurface. Now, a few theoretical frameworks exist that help to define Stygian life. Temperature, redox gradients, productivity (e.g., in the overlying ocean), and microbial power requirements are thought to determine the distribution of microbes in the subsurface. Still, we struggle to comprehend the spatial and temporal spectra of Earth processes that define how deep microbe communities survive. Stommel diagrams, originally used to guide oceanographic sampling, may be useful in depicting the subsurface where microbial communities are impacted by co-occurring spatial and temporal phenomena that range across exponential scales. Spatially, the geological settings that influence the activity and distribution of microbes range from individual molecules or minerals all the way up to the planetary-scale where geological formations, occupying up to 105 km3, dictate the bio- and functional geography of microbial communities. Temporally, life in the subsurface may respond in time units familiar to humans (e.g., seconds to days) or to events that unfold over hundred millennial time periods. While surface community dynamics are underpinned by solar and lunar cycles, these cycles only fractionally dictate survival underground where phenomena like tectonic activity, isostatic rebound, and radioactive decay are plausible drivers of microbial life. Geological or planetary processes that occur on thousand or million year cycles could be uniquely important to microbial viability in the subsurface. Such an approach aims at a holistic comprehension of the interaction of Earth system dynamics with microbial ecology.

Using a Process Based Model to Simulate the Effects of Drainage and Land Use Change on Hydrology, and Sediment and Nutrient Transport in the Midwestern United States

NASA Astrophysics Data System (ADS)

Downer, C. W.; Pradhan, N. R.; Skahill, B. E.; Wahl, M.; Turnbull, S. J.

2015-12-01

Historically the Midwestern United State was a region dominated by prairie grasses and wetlands. To make use of the rich soils underlying these fertile environments, farmers converted the land to agriculture and currently the Midwest is a region of intensive agricultural production, with agriculture being a predominant land use. The Midwest is a region of gentle slopes, tight soils, and high water tables, and in order to make the lands suitable for agriculture, farmers have installed extensive networks of ditches to drain off excess surface water and subsurface tiles to lower the water table and remove excess soil water in the root zone that can stress common row crops, such as corn and soybeans. The combination of tiles, ditches, and intensive agricultural land practices radically alters the landscape and hydrology. As part of the Minnesota River Basin Integrated Study we are simulating nested watersheds in a sub-basin of the Minnesota River Basin, Seven Mile Creek, using the physics-based watershed model GSSHA (Gridded Surface Subsurface Hydrologic Analysis) to simulate water, sediment, and nutrients. Representative of the larger basin, more than 80% of the land in the watershed is dedicated to agricultural practices. From a process perspective, the hydrology is complicated, with snow accumulation and melt, frozen soil, and tile drains all being important processes within the watershed. In this study we attempt to explicitly simulate these processes, including the tile drains, which are simulated as a network of subsurface pipes that collect water from the local water table. Within the watershed, tiles discharge to both the ditch/stream network as well as overland locations, where the tile discharge appears to initiate gullies and exacerbate overland erosion. Testing of the methods on smaller basins demonstrates the ability of the model to simulate measured tile flow. At the larger scale, the model demonstrates ability to simulate flow and sediments. Sparse nutrient data limit the assessment of nutrient simulations. The models are being used to asses an array of potential future land use scenarios, including predevelopment and increased agricultural use. Results from these simulations will be presented. Preliminary results indicate that tile drains increase discharge and erosion in the watershed.

Quantification of microbial activity in subsurface environments using a hydrogenase enzyme assay

NASA Astrophysics Data System (ADS)

Adhikari, R. R.; Nickel, J.; Kallmeyer, J.

2012-04-01

The subsurface biosphere is the largest microbial ecosystem on Earth. Despite its large size and extensive industrial exploitation, very little is known about the role of microbial activity in the subsurface. Subsurface microbial activity plays a fundamental role in geochemical cycles of carbon and other biologically important elements. How the indigenous microbial communities are supplied with energy is one of the most fundamental questions in subsurface research. It is still an enigma how these communities can survive with such recalcitrant carbon over geological time scales. Despite its usually very low concentration, hydrogen is an important element in subsurface environments. Heterotrophic and chemoautotrophic microorganisms use hydrogen in their metabolic pathways; they either obtain protons from the radiolysis of water and/or cleavage of hydrogen generated by the alteration of basaltic crust, or they dispose of protons by formation of water. Hydrogenase (H2ase) is a ubiquitous intracellular enzyme that catalyzes the interconversion of molecular hydrogen and/or water into protons and electrons. The protons are used for the synthesis of ATP, thereby coupling energy-generating metabolic processes to electron acceptors such as carbon dioxide or sulfate. H2ase activity can therefore be used as a measure for total microbial activity as it targets a key metabolic compound rather than a specific turnover process. Using a highly sensitive tritium assay we measured H2ase enzyme activity in the organic-rich sediments of Lake Van, a saline, alkaline lake in eastern Turkey and in marine subsurface sediments of the Barents Sea. Additionally, sulfate reduction rates (SRRs) were measured to compare the results of the H2ase enzyme assay with the quantitatively most important electron acceptor process. H2ase activity was found at all sites, measured values and distribution of activity varied widely with depth and between sites. At the Lake Van sites H2ase activity ranged from ca. 20 mmol H2 cm-3 d-1 close to the sediment-water interface to 0.5 mmol H2 cm-3 d-1 at a depth of 0.8 m. In samples from the Barents Sea H2ase activity ranged between 0.1 to 2.5 mmol H2 cm-3 d-1 down to a depth of 1.60 m. At all sites the SRR profile followed the H2ase activity profile until SRR declined to values close to the minimum detection limit (~10 pmol cm-3 d-1). H2ase activity increased again after SRR declined, indicating that other microbial processes are becoming quantitatively more important. The H2ase and SRR data show that our assay has a potential to become a valuable tool to measure total subsurface microbial activity.

An integrated geophysical and geochemical exploration of critical zone weathering on opposing montane hillslope

NASA Astrophysics Data System (ADS)

Singha, K.; Navarre-Sitchler, A.; Bandler, A.; Pommer, R. E.; Novitsky, C. G.; Holbrook, S.; Moore, J.

2017-12-01

Quantifying coupled geochemical and hydrological properties and processes that operate in the critical zone is key to predicting rock weathering and subsequent transmission and storage of water in the shallow subsurface. Geophysical data have the potential to elucidate geochemical and hydrologic processes across landscapes over large spatial scales that are difficult to achieve with point measurements alone. Here, we explore the connections between weathering and fracturing, as measured from integrated geochemical and geophysical borehole data and seismic velocities on north- and south-facing aspects within one watershed in the Boulder Creek Critical Zone Observatory. We drilled eight boreholes up to 13 m deep on north- and south-facing aspects within Upper Gordon Gulch, and surface seismic refraction data were collected near these wells to explore depths of regolith and bedrock, as well as anisotropic characteristics of the subsurface material due to fracturing. Optical televiewer data were collected in these wells to infer the dominant direction of fracturing and fracture density in the near surface to corroborate with the seismic data. Geochemical samples were collected from four of these wells and a series of shallow soil pits for bulk chemistry, clay fraction, and exchangeable cation concentrations to identify depths of chemically altered saprolite. Seismic data show that depth to unweathered bedrock, as defined by p-wave seismic velocity, is slightly thicker on the north-facing slopes. Geochemical data suggest that the depth to the base of saprolite ranges from 3-5 m, consistent with a p-wave velocity value of 1200 m/s. Based on magnitude and anisotropy of p-wave velocities together with optical televiewer data, regolith on north-facing slopes is thought to be more fractured than south-facing slopes, while geochemical data indicate that position on the landscape is another important characteristic in determining depths of weathering. We explore the importance of fracture opening in controlling both saprolite and regolith thickness within this watershed.

Continuous monitoring of the lunar or Martian subsurface using on-board pattern recognition and neural processing of Rover geophysical data

NASA Technical Reports Server (NTRS)

Mcgill, J. W.; Glass, C. E.; Sternberg, B. K.

1990-01-01

The ultimate goal is to create an extraterrestrial unmanned system for subsurface mapping and exploration. Neural networks are to be used to recognize anomalies in the profiles that correspond to potentially exploitable subsurface features. The ground penetrating radar (GPR) techniques are likewise identical. Hence, the preliminary research focus on GPR systems will be directly applicable to seismic systems once such systems can be designed for continuous operation. The original GPR profile may be very complex due to electrical behavior of the background, targets, and antennas, much as the seismic record is made complex by multiple reflections, ghosting, and ringing. Because the format of the GPR data is similar to the format of seismic data, seismic processing software may be applied to GPR data to help enhance the data. A neural network may then be trained to more accurately identify anomalies from the processed record than from the original record.

Integrated reservoir characterization for unconventional reservoirs using seismic, microseismic and well log data

NASA Astrophysics Data System (ADS)

Maity, Debotyam

This study is aimed at an improved understanding of unconventional reservoirs which include tight reservoirs (such as shale oil and gas plays), geothermal developments, etc. We provide a framework for improved fracture zone identification and mapping of the subsurface for a geothermal system by integrating data from different sources. The proposed ideas and methods were tested primarily on data obtained from North Brawley geothermal field and the Geysers geothermal field apart from synthetic datasets which were used to test new algorithms before actual application on the real datasets. The study has resulted in novel or improved algorithms for use at specific stages of data acquisition and analysis including improved phase detection technique for passive seismic (and teleseismic) data as well as optimization of passive seismic surveys for best possible processing results. The proposed workflow makes use of novel integration methods as a means of making best use of the available geophysical data for fracture characterization. The methodology incorporates soft computing tools such as hybrid neural networks (neuro-evolutionary algorithms) as well as geostatistical simulation techniques to improve the property estimates as well as overall characterization efficacy. The basic elements of the proposed characterization workflow involves using seismic and microseismic data to characterize structural and geomechanical features within the subsurface. We use passive seismic data to model geomechanical properties which are combined with other properties evaluated from seismic and well logs to derive both qualitative and quantitative fracture zone identifiers. The study has resulted in a broad framework highlighting a new technique for utilizing geophysical data (seismic and microseismic) for unconventional reservoir characterization. It provides an opportunity to optimally develop the resources in question by incorporating data from different sources and using their temporal and spatial variability as a means to better understand the reservoir behavior. As part of this study, we have developed the following elements which are discussed in the subsequent chapters: 1. An integrated characterization framework for unconventional settings with adaptable workflows for all stages of data processing, interpretation and analysis. 2. A novel autopicking workflow for noisy passive seismic data used for improved accuracy in event picking as well as for improved velocity model building. 3. Improved passive seismic survey design optimization framework for better data collection and improved property estimation. 4. Extensive post-stack seismic attribute studies incorporating robust schemes applicable in complex reservoir settings. 5. Uncertainty quantification and analysis to better quantify property estimates over and above the qualitative interpretations made and to validate observations independently with quantified uncertainties to prevent erroneous interpretations. 6. Property mapping from microseismic data including stress and anisotropic weakness estimates for integrated reservoir characterization and analysis. 7. Integration of results (seismic, microseismic and well logs) from analysis of individual data sets for integrated interpretation using predefined integration framework and soft computing tools.

Subsurface Contamination Control

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

Y. Yuan

There are two objectives of this report, ''Subsurface Contamination Control''. The first is to provide a technical basis for recommending limiting radioactive contamination levels (LRCL) on the external surfaces of waste packages (WP) for acceptance into the subsurface repository. The second is to provide an evaluation of the magnitude of potential releases from a defective WP and the detectability of the released contents. The technical basis for deriving LRCL has been established in ''Retrieval Equipment and Strategy for Wp on Pallet'' (CRWMS M and O 2000g, 6.3.1). This report updates the derivation by incorporating the latest design information of themore » subsurface repository for site recommendation. The derived LRCL on the external surface of WPs, therefore, supercede that described in CRWMS M and O 2000g. The derived LRCL represent the average concentrations of contamination on the external surfaces of each WP that must not be exceeded before the WP is to be transported to the subsurface facility for emplacement. The evaluation of potential releases is necessary to control the potential contamination of the subsurface repository and to detect prematurely failed WPs. The detection of failed WPs is required in order to provide reasonable assurance that the integrity of each WP is intact prior to MGR closure. An emplaced WP may become breached due to manufacturing defects or improper weld combined with failure to detect the defect, by corrosion, or by mechanical penetration due to accidents or rockfall conditions. The breached WP may release its gaseous and volatile radionuclide content to the subsurface environment and result in contaminating the subsurface facility. The scope of this analysis is limited to radioactive contaminants resulting from breached WPs during the preclosure period of the subsurface repository. This report: (1) documents a method for deriving LRCL on the external surfaces of WP for acceptance into the subsurface repository; (2) provides a table of derived LRCL for nuclides of radiological importance; (3) Provides an as low as is reasonably achievable (ALARA) evaluation of the derived LRCL by comparing potential onsite and offsite doses to documented ALARA requirements; (4) Provides a method for estimating potential releases from a defective WP; (5) Provides an evaluation of potential radioactive releases from a defective WP that may become airborne and result in contamination of the subsurface facility; and (6) Provides a preliminary analysis of the detectability of a potential WP leak to support the design of an airborne release monitoring system.« less

Portable Electromagnetic Induction Sensor with Integrated Positioning

DTIC Science & Technology

2013-08-20

Subsurface electromagnetic induction imaging for unexploded ordnance detection. Journal of Applied Geophysics, 79:38 – 45, 2012. ISSN 09269851. URL http...Portable Electromagnetic Induction Sensor with Integrated Positioning MR-1712 Final Report Submitted to Strategic Environmental Research and...19a. NAME OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (include area code) Standard Form 298 (Rev. 8–98) Prescribed by ANSI Std. Z39.18 06–25–2013

Karst aquifer characterization using geophysical remote sensing of dynamic recharge events

NASA Astrophysics Data System (ADS)

Grapenthin, R.; Bilek, S. L.; Luhmann, A. J.

2017-12-01

Geophysical monitoring techniques, long used to make significant advances in a wide range of deeper Earth science disciplines, are now being employed to track surficial processes such as landslide, glacier, and river flow. Karst aquifers are another important hydrologic resource that can benefit from geophysical remote sensing, as this monitoring allows for safe, noninvasive karst conduit measurements. Conduit networks are typically poorly constrained, let alone the processes that occur within them. Geophysical monitoring can also provide a regionally integrated analysis to characterize subsurface architecture and to understand the dynamics of flow and recharge processes in karst aquifers. Geophysical signals are likely produced by several processes during recharge events in karst aquifers. For example, pressure pulses occur when water enters conduits that are full of water, and experiments suggest seismic signals result from this process. Furthermore, increasing water pressure in conduits during recharge events increases the load applied to conduit walls, which deforms the surrounding rock to yield measureable surface displacements. Measureable deformation should also occur with mass loading, with subsidence and rebound signals associated with increases and decreases of water mass stored in the aquifer, respectively. Additionally, geophysical signals will likely arise with turbulent flow and pore pressure change in the rock surrounding conduits. Here we present seismic data collected during a pilot study of controlled and natural recharge events in a karst aquifer system near Bear Spring, near Eyota, MN, USA as well as preliminary model results regarding the processes described above. In addition, we will discuss an upcoming field campaign where we will use seismometers, tiltmeters, and GPS instruments to monitor for recharge-induced responses in a FL, USA karst system with existing cave maps, coupling these geophysical observations with hydrologic and meteorologic data to map and characterize conduits and other features of the larger karst system and to monitor subsurface flow dynamics during recharge events.

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.

Landslide maps and seismic noise: Rockmass weakening caused by shallow earthquakes

NASA Astrophysics Data System (ADS)

Uchida, Tara; Marc, Odin; Sens-Schönfelder, Christoph; Sawazaki, Kaoru; Hobiger, Manuel; Hovius, Niels

2015-04-01

Some studies have suggested that the shaking and deformation associated with earthquake would result in a temporary increased hillslope erodibility. However very few data have been able to clarify such effect. We present integrated geomorphic data constraining an elevated landslide rate following 4 continental shallow earthquakes, the Mw 6.9 Finisterre (1993), the Mw 7.6 ChiChi (1999), the Mw 6.6 Niigata (2004) and the Mw 6.8 Iwate-Miyagi (2008) earthquakes. We constrained the magnitude, the recovery time and somewhat the mechanism at the source of this higher landslide risk. We provide some evidences excluding aftershocks or rain forcing intensity as possible mechanism and leaving subsurface weakening as the most likely. The landslide data suggest that this ground strength weakening is not limited to the soil cover but also affect the shallow bedrock. Additionally, we used ambient noise autocorrelation techniques to monitor shallow subsurface seismic velocity within the epicentral area of three of those earthquakes. For most stations we observe a velocity drop followed by a recovery processes of several years in fair agreement with the recovery time estimated based on landslide observation. Thus a common processes could alter the strength of the first 10m of soil/rock and simultaneously drive the landslide rate increase and the seismic velocity drop. The ability to firmly demonstrate this link require additional constraints on the seismic signal interpretation but would provide a very useful tool for post-earthquake risk managment.

Hydrologic impacts of thawing permafrost—A review

USGS Publications Warehouse

Walvoord, Michelle Ann; Kurylyk, Barret L.

2016-01-01

Where present, permafrost exerts a primary control on water fluxes, flowpaths, and distribution. Climate warming and related drivers of soil thermal change are expected to modify the distribution of permafrost, leading to changing hydrologic conditions, including alterations in soil moisture, connectivity of inland waters, streamflow seasonality, and the partitioning of water stored above and below ground. The field of permafrost hydrology is undergoing rapid advancement with respect to multiscale observations, subsurface characterization, modeling, and integration with other disciplines. However, gaining predictive capability of the many interrelated consequences of climate change is a persistent challenge due to several factors. Observations of hydrologic change have been causally linked to permafrost thaw, but applications of process-based models needed to support and enhance the transferability of empirical linkages have often been restricted to generalized representations. Limitations stem from inadequate baseline permafrost and unfrozen hydrogeologic characterization, lack of historical data, and simplifications in structure and process representation needed to counter the high computational demands of cryohydrogeologic simulations. Further, due in part to the large degree of subsurface heterogeneity of permafrost landscapes and the nonuniformity in thaw patterns and rates, associations between various modes of permafrost thaw and hydrologic change are not readily scalable; even trajectories of change can differ. This review highlights promising advances in characterization and modeling of permafrost regions and presents ongoing research challenges toward projecting hydrologic and ecologic consequences of permafrost thaw at time and spatial scales that are useful to managers and researchers.

Uranium interaction with soil minerals in the presence of co-contaminants: Case Study- subsurface sediments at or below the water table

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

Gartman, Brandy N.; Qafoku, Nikolla

2016-03-09

Uranium (U) contaminated subsurface systems are common on a global scale mainly because of its essential role in the production of plutonium for nuclear weapons and other nuclear energy and research activities. Studying the behavior and fate of U in these systems is challenging because of heterogeneities of different types (i.e., physical, chemical and mineralogical) and a complex network of often time-dependent hydrological, biological and chemical reactions and processes that occur sequentially or simultaneously, affecting and/or controlling U mobility. A U contaminated site, i.e., the Integrated Field Research Challenge site in Rifle, CO, USA (a former U mill site) ismore » the focus of this discussion. The overall objectives of this chapter are to 1) provide an overview of the contamination levels (U and other co-contaminants) at this field site; 2) review and discuss different aspects of mineral-U contaminant interactions in reduced and oxidized environments, and in the presence of co-contaminants; 3) present results from a systematic macroscopic, microscopic, and spectroscopic study as an example of the current research efforts and the state-of-knowledge in this important research area; and 4) offer insightful conclusive remarks and future research needs about reactions and processes that control U and other contaminants’ fate and behavior under hydraulically saturated conditions. The implications and applications presented in this chapter are valid for U contaminated sites across the world.« less

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

Lord, Anna C.

The U.S. Strategic Petroleum Reserve (SPR) is a stockpile of emergency crude oil to be tapped into if a disruption in the nation's oil supply occurs. The SPR is comprised of four salt dome sites. Subsidence surveys have been conducted either annually or biennially at all four sites over the life of the program. Monitoring of surface behavior is a first line defense to detecting possible subsurface cavern integrity issues. Over the life of the Bryan Mound site, subsidence rates over abandoned Cavern 3 have continuously been the highest at the site. In an effort to try and understand themore » subsurface dynamics, specifically over Bryan Mound Cavern 3, historic interferometric synthetic aperture radar (InSAR) data was acquired and processed by TRE Altamira. InSAR involves the processing of multiple satellite synthetic aperture radar scenes acquired across the same location of the Earth's surface at different times to map surface deformation. The analysis of the data has the ability to detect millimeters of motion spanning days, months, year and decades, across specific sites. The intent in regards to the Bryan Mound site was (1) to confirm the higher subsidence rates recorded over abandoned Cavern 3 indicated by land survey and (2) understand the regional surface behavior. This report describes the InSAR analysis results, how those results compare to the historical collection of land survey data, and what additional information the data has provided towards understanding the response recorded at the surface.« less

Integrating hydrologic and geophysical data to constrain coastal surficial aquifer processes at multiple spatial and temporal scales

USGS Publications Warehouse

Schultz, Gregory M.; Ruppel, Carolyn; Fulton, Patrick; Hyndman, David W.; Day-Lewis, Frederick D.; Singha, Kamini

2007-01-01

Since 1997, repeated, coincident geophysical surveys and extensive hydrologic studies in shallow monitoring wells have been used to study static and dynamic processes associated with surface water-groundwater interaction at a range of spatial scales at the estuarine and ocean boundaries of an undeveloped, permeable barrier island in the Georgia part of the U.S. South Atlantic Bight. Because geophysical and hydrologic data measure different parameters, at different resolution and precision, and over vastly different spatial scales, reconciling the coincident data or even combining complementary inversion, hydrogeochemcial analyses and well-based groundwater monitoring, and, in some cases, limited vegetation mapping to demonstrate the utility of an integrative, multidisciplinary approach for elucidating groundwater processes at spatial scales (tens to thousands of meters) that are often difficult to capture with traditional hydrologic approaches. The case studies highlight regional aquifer characteristics, varying degrees of lateral saltwater intrusion at estuarine boundaries, complex subsurface salinity gradients at the ocean boundary, and imaging of submarsh groundwater discharge and possible free convection in the pore waters of a clastic marsh. This study also documents the use of geophysical techniques for detecting temporal changes in groundwater salinity regimes under natural (not forced) gradients at intratidal to interannual (1998-200 Southeastern U.S.A. drought) time scales.

Design and Evaluation of a Fiber Optic Probe as a means of Subsurface Planetary Exploration

NASA Astrophysics Data System (ADS)

Pilgrim, Robert Paul

The Optical Probe for Regolith Analysis (OPRA) is an instrumentation concept designed to provide spectroscopic analysis of the near subsurface of unconsolidated regolith on bodies such as moons, asteroids and planets. Below a chemically altered surface may lay the geological history in the form of stratigraphy that is shielded from degradation due to harsh external environments. Most of what we know about our solar system comes from remote platforms, such as satellites that are deployed into orbit around the target body. In the case of Mars, we have had several successful landers and rovers however, with the exception of the Mars Science Laboratory that just drilled its first hole, the complexity of subsurface excavation has limited the extent of subsurface exploration to simple scoops deployed on the ends of robotic arms which, by their very nature, will erase any stratigraphy that it may be digging into. The OPRA instrumentation concept allows for an integrated, lightweight and simple apparatus for subsurface exploration via a small, spike like structure which contains integrated optical fibers coupled to small windows running down the length of the probe. Each window is connected to a spectrometer housed onboard the deploying spacecraft. Each window is separately interrogated via the spectrometer over the wavelength range 1-2.5 nm to produce a spectroscopic profile as a function of depth. This project takes the Technology Readiness Level (TRL) of the OPRA instrumentation concept to level 3, which is defined by NASA to be the demonstration either analytically or experimentally of the proof of concept for critical functions of the proposed instrument. Firstly, to demonstrate that optical fibers are feasible for this type of application, we report on the techniques used by NASA to space qualify optical fibers. We investigate the optical performance of several fiber optic bundle configurations, both experimentally and numerically, to help optimize bundle performance. Optical bundles were then spectrally validated via a series of spectral comparisons between standardized reflectance spectroscopy targets and spectra obtained with the bundles. We also report on the integration of fiber optical bundles into other research and experimental results from several other groups within our research teams to obtain spectra under a more "space like" environment. Finally, the probe housing structural performance was investigated via finite element analysis, using probe penetration forces derived from data analysis of experimentation conducted by the Apollo lunar missions, and investigations into a mechanical analogue for the Martian regolith.

Low frequency acoustic microscope

DOEpatents

Khuri-Yakub, Butrus T.

1986-11-04

A scanning acoustic microscope is disclosed for the detection and location of near surface flaws, inclusions or voids in a solid sample material. A focused beam of acoustic energy is directed at the sample with its focal plane at the subsurface flaw, inclusion or void location. The sample is scanned with the beam. Detected acoustic energy specularly reflected and mode converted at the surface of the sample and acoustic energy reflected by subsurface flaws, inclusions or voids at the focal plane are used for generating an interference signal which is processed and forms a signal indicative of the subsurface flaws, inclusions or voids.

Separation of toxic metal ions, hydrophilic hydrocarbons, hydrophobic fuel and halogenated hydrocarbons and recovery of ethanol from a process stream

DOEpatents

Kansa, E.J.; Anderson, B.L.; Wijesinghe, A.M.; Viani, B.E.

1999-05-25

This invention provides a process to tremendously reduce the bulk volume of contaminants obtained from an effluent stream produced subsurface remediation. The chemicals used for the subsurface remediation are reclaimed for recycling to the remediation process. Additional reductions in contaminant bulk volume are achieved by the ultra-violet light destruction of halogenated hydrocarbons, and the complete oxidation of hydrophobic fuel hydrocarbons and hydrophilic hydrocarbons. The contaminated bulk volume will arise primarily from the disposal of the toxic metal ions. The entire process is modular, so if there are any technological breakthroughs in one or more of the component process modules, such modules can be readily replaced. 3 figs.

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.

Towards a high resolution, integrated hydrology model of North America: Diagnosis of feedbacks between groundwater and land energy fluxes at continental scales.

NASA Astrophysics Data System (ADS)

Maxwell, Reed; Condon, Laura

2016-04-01

Recent studies demonstrate feedbacks between groundwater dynamics, overland flow, land surface and vegetation processes, and atmospheric boundary layer development that significantly affect local and regional climate across a range of climatic conditions. Furthermore, the type and distribution of vegetation cover alters land-atmosphere water and energy fluxes, as well as runoff generation and overland flow processes. These interactions can result in significant feedbacks on local and regional climate. In mountainous regions, recent research has shown that spatial and temporal variability in annual evapotranspiration, and thus water budgets, is strongly dependent on lateral groundwater flow; however, the full effects of these feedbacks across varied terrain (e.g. from plains to mountains) are not well understood. Here, we present a high-resolution, integrated hydrology model that covers much of continental North America and encompasses the Mississippi and Colorado watersheds. The model is run in a fully-transient manner at hourly temporal resolution incorporating fully-coupled land energy states and fluxes with integrated surface and subsurface hydrology. Connections are seen between hydrologic variables (such as water table depth) and land energy fluxes (such as latent heat) and spatial and temporal scaling is shown to span many orders of magnitude. Model results suggest that partitioning of plant transpiration to bare soil evaporation is a function of water table depth and later groundwater flow. Using these transient simulations as a proof of concept, we present a vision for future integrated simulation capabilities.

Development of the Hydrological-Ecological Integrated watershed Flow Model (HEIFLOW): an application to the Heihe River Basin

NASA Astrophysics Data System (ADS)

Tian, Y.; Zheng, Y.; Zheng, C.; Han, F., Sr.

2017-12-01

Physically based and fully-distributed integrated hydrological models (IHMs) can quantitatively depict hydrological processes, both surface and subsurface, with sufficient spatial and temporal details. However, the complexity involved in pre-processing data and setting up models seriously hindered the wider application of IHMs in scientific research and management practice. This study introduces our design and development of Visual HEIFLOW, hereafter referred to as VHF, a comprehensive graphical data processing and modeling system for integrated hydrological simulation. The current version of VHF has been structured to accommodate an IHM named HEIFLOW (Hydrological-Ecological Integrated watershed-scale FLOW model). HEIFLOW is a model being developed by the authors, which has all typical elements of physically based and fully-distributed IHMs. It is based on GSFLOW, a representative integrated surface water-groundwater model developed by USGS. HEIFLOW provides several ecological modules that enable to simulate growth cycle of general vegetation and special plants (maize and populus euphratica). VHF incorporates and streamlines all key steps of the integrated modeling, and accommodates all types of GIS data necessary to hydrological simulation. It provides a GIS-based data processing framework to prepare an IHM for simulations, and has functionalities to flexibly display and modify model features (e.g., model grids, streams, boundary conditions, observational sites, etc.) and their associated data. It enables visualization and various spatio-temporal analyses of all model inputs and outputs at different scales (i.e., computing unit, sub-basin, basin, or user-defined spatial extent). The above system features, as well as many others, can significantly reduce the difficulty and time cost of building and using a complex IHM. The case study in the Heihe River Basin demonstrated the applicability of VHF for large scale integrated SW-GW modeling. Visualization and spatial-temporal analysis of the modeling results by HEIFLOW greatly facilitates our understanding on the complicated hydrologic cycle and relationship among the hydrological and ecological variables in the study area, and provides insights into the regional water resources management.

Analysis and interpretation of geophysical surveys in archaeological sites employing different integrated approach.

NASA Astrophysics Data System (ADS)

Piro, Salvatore; Papale, Enrico; Kucukdemirci, Melda; Zamuner, Daniela

2017-04-01

Non-destructive ground surface geophysical prospecting methods are frequently used for the investigation of archaeological sites, where a detailed physical and geometrical reconstructions of hidden volumes is required prior to any excavation work. All methods measure the variations of single physical parameters, therefore if these are used singularly, they could not permit a complete location and characterization of anomalous bodies. The probability of a successful result rapidly increases if a multhimethodological approach is adopted, according to the logic of objective complementarity of information and of global convergence toward a high quality multiparametric imaging of the buried structures. The representation of the static configuration of the bodies in the subsoil and of the space-time evolution of the interaction processes between targets and hosting materials have to be actually considered fundamental elements of primary knowledge in archaeological prospecting. The main effort in geophysical prospecting for archaeology is therefore the integration of different, absolutely non-invasive techniques, especially if managed in view of a ultra-high resolution three-dimensional (3D) tomographic representation mode. Following the above outlined approach, we have integrated geophysical methods which measure the variations of potential field (gradiometric methods) with active methods which measure the variations of physical properties due to the body's geometry and volume (GPR and ERT). In this work, the results obtained during the surveys of three archaeological sites, employing Ground Penetrating Radar (GPR), Electrical Resistivity Tomography (ERT) and Fluxgate Differential Magnetic (FDM) to obtain precise and detailed maps of subsurface bodies, are presented and discussed. The first site, situated in a suburban area between Itri and Fondi, in the Aurunci Natural Regional Park (Central Italy), is characterized by the presence of remains of past human activity dating from the third century B.C. The second site is always in suburban area and is part of the ancient acropolis Etruscan town of Cerveteri (central Italy). The third site is part of Aizanoi archaeological park (Cavdarhisar, Kutahya, Turkey). To have a better understanding of the subsurface, we performed a different integrated approaches of these data, which consists in fusing the data from all the employed methods, to have a complete visualization of the investigated area. For the processing we have used the following techniques: graphical integration (overlay and RGB colour composite), discrete data analysis (binary data analysis and cluster analysis) and continuous data analysis (data sum, product, max, min and PCA). Ernenwein, E.G. 2009. Integration of multidimensional archaeogeophysical data using supervised and unsupervised classification. Near surface geophysics. Vol 7: 147-158. DOI:10.3997/1873-0604.2009004 Kucukdemirci,M., Piro.S.,Baydemir,N.,Ozer.,E. Zamuner.,D. 2015. Mathematical and Statistical Integration approach on archaeological prospection data,case studies from Aizanoi-Turkey. 43rd Computer Applications and Quantitative Methods in Archaeology, Siena. Kvamme,K.,2007. Integrating Multiple Geophysical Datasets, Remote Sensing in archaeology, Springer,Boston. Piro,S.,Mauriello.,P. and Cammarano.,F.2000. Quantitative Integration of Geophysical methods for Archaeological Prospection. Archaeological prospection 7(4): 203-213. Piro S., Papale E., Zamuner D., 2016. Different integrated geophysical approaches to investigate archaeological sites in urban and suburban area. Geophysical Research Abstracts Vol. 18, EGU2016.

Recovery of community genomes to assess subsurface metabolic potential: exploiting the capacity of next generation sequencing-based metagenomics

NASA Astrophysics Data System (ADS)

Wrighton, K. C.; Thomas, B.; Miller, C. S.; Sharon, I.; Wilkins, M. J.; VerBerkmoes, N. C.; Handley, K. M.; Lipton, M. S.; Hettich, R. L.; Williams, K. H.; Long, P. E.; Banfield, J. F.

2011-12-01

With the goal of developing a deterministic understanding of the microbiological and geochemical processes controlling subsurface environments, groundwater bacterial communities were collected from the Rifle Integrated Field Research Challenge (IFRC) site. Biomass from three temporal acetate-stimulated groundwater samples were collected during a period of dominant Fe(III)-reduction, in a region of the aquifer that had previously received acetate amendment the year prior. Phylogenetic analysis revealed a diverse Bacterial community, notably devoid of Archaea with 249 taxa from 9 Bacterial phyla including the dominance of uncultured candidate divisions, BD1-5, OD1, and OP11. We have reconstructed 86 partial to near-complete genomes and have performed a detailed characterization of the underlying metabolic potential of the ecosystem. We assessed the natural variation and redundancy in multi-heme c-type cytochromes, sulfite reductases, and central carbon metabolic pathways. Deep genomic sampling indicated the community contained various metabolic pathways: sulfur oxidation coupled to microaerophilic conditions, nitrate reduction with both acetate and inorganic compounds as donors, carbon and nitrogen fixation, antibiotic warfare, and heavy-metal detoxification. Proteomic investigations using predicted proteins from metagenomics corroborated that acetate oxidation is coupled to reduction of oxygen, sulfur, nitrogen, and iron across the samples. Of particular interest was the detection of acetate oxidizing and sulfate reducing proteins from a Desulfotalea-like bacterium in all three time points, suggesting that aqueous sulfide produced by active sulfate-reducing bacteria could contribute to abiotic iron reduction during the dominant iron reduction phase. Additionally, proteogenomic analysis verified that a large portion of the community, including members of the uncultivated BD1-5, are obligate fermenters, characterized by the presence of hydrogen-evolving hydrogenases, the capacity to oxidize complex organic carbon, as well as lack of membrane bound electron transport chains and an incomplete citric acid cycle. We propose that these organisms grow cryptically on residual biomass from previous biostimulation experiments and thus demonstrate that resource utilization and turnover in the aquifer can be decoupled from existing acetate amendment and external terminal electron accepting processes. In addition to the first recovery of multiple genomes from these novel candidate divisions, our community genomic approach uncovered viral diversity not yet observed at the site, with the reconstruction of six phage genomes and the presence of CRISPR loci detected in bacterial genomes from diverse lineages. These findings have implications for predictive ecosystem modeling, highlighting the importance of integrating the response, adaptation, as well as biological and geochemical feedback mechanisms existing within complex subsurface communities to long term organic carbon amendment.

Long-term predictions of minewater geothermal systems heat resources

NASA Astrophysics Data System (ADS)

Harcout-Menou, Virginie; de ridder, fjo; laenen, ben; ferket, helga

2014-05-01

Abandoned underground mines usually flood due to the natural rise of the water table. In most cases the process is relatively slow giving the mine water time to equilibrate thermally with the the surrounding rock massif. Typical mine water temperature is too low to be used for direct heating, but is well suited to be combined with heat pumps. For example, heat extracted from the mine can be used during winter for space heating, while the process could be reversed during summer to provide space cooling. Altough not yet widely spread, the use of low temperature geothermal energy from abandoned mines has already been implemented in the Netherlands, Spain, USA, Germany and the UK. Reliable reservoir modelling is crucial to predict how geothermal minewater systems will react to predefined exploitation schemes and to define the energy potential and development strategy of a large-scale geothermal - cold/heat storage mine water systems. However, most numerical reservoir modelling software are developed for typical environments, such as porous media (a.o. many codes developed for petroleum reservoirs or groundwater formations) and cannot be applied to mine systems. Indeed, mines are atypical environments that encompass different types of flow, namely porous media flow, fracture flow and open pipe flow usually described with different modelling codes. Ideally, 3D models accounting for the subsurface geometry, geology, hydrogeology, thermal aspects and flooding history of the mine as well as long-term effects of heat extraction should be used. A new modelling approach is proposed here to predict the long-term behaviour of Minewater geothermal systems in a reactive and reliable manner. The simulation method integrates concepts for heat and mass transport through various media (e.g., back-filled areas, fractured rock, fault zones). As a base, the standard software EPANET2 (Rossman 1999; 2000) was used. Additional equations for describing heat flow through the mine (both through open pipes and from the rock massif) have been implemented. Among others, parametric methods are used to bypass some shortcomings in the physical models used for the subsurface. The advantage is that the complete geometry of the mine workings can be integrated and that computing is fast enough to allow implementing and testing several scenarios (e.g. contributions from fault zones, different assumptions about the actual status of shafts, drifts and mined out areas) in an efficient way (Ferket et al., 2011). EPANET allows to incorporate the full complexity of the subsurface mine structure. As a result, the flooded mine is considered as a network of pipes, each with a custom-defined diameter, length and roughness.

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

The MONACO project (Monitoring approach for geological CO2 storage sites using a hierarchic observation concept) aims to find reliable monitoring tools that work on different spatial and temporal scales at geological CO2 storage sites. This integrative hierarchical monitoring approach based on different levels of coverage and resolutions is proposed as a means of reliably detecting CO2 degassing areas at ground surface level and for identifying CO2 leakages from storage formations into the shallow subsurface, as well as CO2 releases into the atmosphere. As part of this integrative hierarchical monitoring concept, several methods and technologies from ground-based remote sensing (Open-path Fourier-transform infrared (OP-FTIR) spectroscopy), regional measurements (near-surface geophysics, chamber-based soil CO2 flux measurement) and local in-situ measurements (using shallow boreholes) will either be combined or used complementary to one another. The proposed combination is a suitable concept for investigating CO2 release sites. This also presents the possibility of adopting a modular monitoring concept whereby our monitoring approach can be expanded to incorporate other methods in various coverage scales at any temporal resolution. The link between information obtained from large-scale surveys and local in-situ monitoring can be realized by sufficient geophysical techniques for meso-scale monitoring, such as geoelectrical and self-potential (SP) surveys. These methods are useful for characterizing fluid flow and transport processes in permeable near-surface sedimentary layers and can yield important information concerning CO2-affected subsurface structures. Results of measurements carried out a natural analogue site in the Czech Republic indicate that the hierarchical monitoring approach represents a successful multidisciplinary modular concept that can be used to monitor both physical and chemical processes taking place during CO2 migration and seepage. The application of FTIR spectroscopy in combination with soil gas surveys and geophysical investigations results in a comprehensive site characterization, including atmospheric and near-surface CO2 distribution, as well as subsurface structural features. We observed a correlation of higher CO2 concentration and flux rates at the meso-scale that coincides with distinct geophysical anomalies. Here, we found prominent SP anomalies and zones of lower resistivity in the geoelectrical images compared to undisturbed regions nearby. This presentation will discuss the results we obtained and illustrate the influence of CO2 on electrical parameters measured under field conditions in relation to environmental parameters.

Hydrologic connectivity as a framework for understanding biogeochemical flux through watersheds and along fluvial networks

NASA Astrophysics Data System (ADS)

Covino, Tim

2017-01-01

Hydrologic connections can link hillslopes to channel networks, streams to lakes, subsurface to surface, land to atmosphere, terrestrial to aquatic, and upstream to downstream. These connections can develop across vertical, lateral, and longitudinal dimensions and span spatial and temporal scales. Each of these dimensions and scales are interconnected, creating a mosaic of nested hydrologic connections and associated processes. In turn, these interacting and nested processes influence the transport, cycling, and transformation of organic material and inorganic nutrients through watersheds and along fluvial networks. Although hydrologic connections span dimensions and spatiotemporal scales, relationships between connectivity and carbon and nutrient dynamics are rarely evaluated within this framework. The purpose of this paper is to provide a cross-disciplinary view of hydrologic connectivity - highlighting the various forms of hydrologic connectivity that control fluxes of organic material and nutrients - and to help stimulate integration across scales and dimensions, and collaboration among disciplines.

Exploration criteria for low permeability geothermal resources. Final report. [Coso KGRA

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

Norton, D.

1977-10-01

Low permeability geothermal systems related to high temperature plutons in the upper crust were analyzed in order to ascertain those characteristics of these systems which could be detected by surface and shallow subsurface exploration methods. Analyses were designed to integrate data and concepts from the literature, which relate to the transport processes, together with computer simulation of idealized systems. The systems were analyzed by systematically varying input parameters in order to understand their effect on the variables which might be measured in an exploration-assessment program. The methods were applied to a prospective system in its early stages of evaluation. Datamore » from the Coso system were used. The study represents a first-order approximation to transport processes in geothermal systems, which consist of high temperature intrusions, host rock, and fluids. Included in an appendix are operations procedures for interactive graphics programs developed during the study. (MHR)« less

Uncertainty of climate change impact on groundwater reserves - Application to a chalk aquifer

NASA Astrophysics Data System (ADS)

Goderniaux, Pascal; Brouyère, Serge; Wildemeersch, Samuel; Therrien, René; Dassargues, Alain

2015-09-01

Recent studies have evaluated the impact of climate change on groundwater resources for different geographical and climatic contexts. However, most studies have either not estimated the uncertainty around projected impacts or have limited the analysis to the uncertainty related to climate models. In this study, the uncertainties around impact projections from several sources (climate models, natural variability of the weather, hydrological model calibration) are calculated and compared for the Geer catchment (465 km2) in Belgium. We use a surface-subsurface integrated model implemented using the finite element code HydroGeoSphere, coupled with climate change scenarios (2010-2085) and the UCODE_2005 inverse model, to assess the uncertainty related to the calibration of the hydrological model. This integrated model provides a more realistic representation of the water exchanges between surface and subsurface domains and constrains more the calibration with the use of both surface and subsurface observed data. Sensitivity and uncertainty analyses were performed on predictions. The linear uncertainty analysis is approximate for this nonlinear system, but it provides some measure of uncertainty for computationally demanding models. Results show that, for the Geer catchment, the most important uncertainty is related to calibration of the hydrological model. The total uncertainty associated with the prediction of groundwater levels remains large. By the end of the century, however, the uncertainty becomes smaller than the predicted decline in groundwater levels.

Integration of real time kinematic satellite navigation with ground-penetrating radar surveys

USDA-ARS?s Scientific Manuscript database

Precision agriculture, environmental mapping, and construction benefit from subsurface imaging by revealing the spatial variability of underground features. Features surveyed of agricultural interest are bedrock depth, soil horizon thicknesses, and buried–object features such as drainage pipe. For t...

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.

GRACE storage-runoff hystereses reveal the dynamics of ...

EPA Pesticide Factsheets

Watersheds function as integrated systems where climate and geology govern the movement of water. In situ instrumentation can provide local-scale insights into the non-linear relationship between streamflow and water stored in a watershed as snow, soil moisture, and groundwater. However, there is a poor understanding of these processes at the regional scale—primarily because of our inability to measure water stores and fluxes in the subsurface. Now NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites quantify changes in the amount of water stored across and through the Earth, providing measurements of regional hydrologic behavior. Here we apply GRACE data to characterize for the first time how regional watersheds function as simple, dynamic systems through a series of hysteresis loops. While the physical processes underlying the loops are inherently complex, the vertical integration of terrestrial water in the GRACE signal provides process-based insights into the dynamic and non-linear function of regional-scale watersheds. We use this process-based understanding with GRACE data to effectively forecast seasonal runoff (mean R2 of 0.91) and monthly runoff (mean R2 of 0.77) in three regional-scale watersheds (>150,000 km2) of the Columbia River Basin, USA. Data from the Gravity Recovery and Climate Experiment (GRACE) satellites provide a novel dataset for understanding changes in the amount of water stored across and through the surface of the Ear

Quantifying Subsurface Water and Heat Distribution and its Linkage with Landscape Properties in Terrestrial Environment using Hydro-Thermal-Geophysical Monitoring and Coupled Inverse Modeling

NASA Astrophysics Data System (ADS)

Dafflon, B.; Tran, A. P.; Wainwright, H. M.; Hubbard, S. S.; Peterson, J.; Ulrich, C.; Williams, K. H.

2015-12-01

Quantifying water and heat fluxes in the subsurface is crucial for managing water resources and for understanding the terrestrial ecosystem where hydrological properties drive a variety of biogeochemical processes across a large range of spatial and temporal scales. Here, we present the development of an advanced monitoring strategy where hydro-thermal-geophysical datasets are continuously acquired and further involved in a novel inverse modeling framework to estimate the hydraulic and thermal parameter that control heat and water dynamics in the subsurface and further influence surface processes such as evapotranspiration and vegetation growth. The measured and estimated soil properties are also used to investigate co-interaction between subsurface and surface dynamics by using above-ground aerial imaging. The value of this approach is demonstrated at two different sites, one in the polygonal shaped Arctic tundra where water and heat dynamics have a strong impact on freeze-thaw processes, vegetation and biogeochemical processes, and one in a floodplain along the Colorado River where hydrological fluxes between compartments of the system (surface, vadose zone and groundwater) drive biogeochemical transformations. Results show that the developed strategy using geophysical, point-scale and aerial measurements is successful to delineate the spatial distribution of hydrostratigraphic units having distinct physicochemical properties, to monitor and quantify in high resolution water and heat distribution and its linkage with vegetation, geomorphology and weather conditions, and to estimate hydraulic and thermal parameters for enhanced predictions of water and heat fluxes as well as evapotranspiration. Further, in the Colorado floodplain, results document the potential presence of only periodic infiltration pulses as a key hot moment controlling soil hydro and biogeochemical functioning. In the arctic, results show the strong linkage between soil water content, thermal parameters, thaw layer thickness and vegetation distribution. Overall, results of these efforts demonstrate the value of coupling various datasets at high spatial and temporal resolution to improve predictive understanding of subsurface and surface dynamics.

Advances in molecular dynamics simulation of ultra-precision machining of hard and brittle materials

NASA Astrophysics Data System (ADS)

Guo, Xiaoguang; Li, Qiang; Liu, Tao; Kang, Renke; Jin, Zhuji; Guo, Dongming

2017-03-01

Hard and brittle materials, such as silicon, SiC, and optical glasses, are widely used in aerospace, military, integrated circuit, and other fields because of their excellent physical and chemical properties. However, these materials display poor machinability because of their hard and brittle properties. Damages such as surface micro-crack and subsurface damage often occur during machining of hard and brittle materials. Ultra-precision machining is widely used in processing hard and brittle materials to obtain nanoscale machining quality. However, the theoretical mechanism underlying this method remains unclear. This paper provides a review of present research on the molecular dynamics simulation of ultra-precision machining of hard and brittle materials. The future trends in this field are also discussed.

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.

A Generalized Subsurface Flow Parameterization Considering Subgrid Spatial Variability of Recharge and Topography

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

Huang, Maoyi; Liang, Xu; Leung, Lai R.

2008-12-05

Subsurface flow is an important hydrologic process and a key component of the water budget, especially in humid regions. In this study, a new subsurface flow formulation is developed that incorporates spatial variability of both topography and recharge. It is shown through theoretical derivation and case studies that the power law and exponential subsurface flow parameterizations and the parameterization proposed by Woods et al.[1997] are all special cases of the new formulation. The subsurface flows calculated using the new formulation compare well with values derived from observations at the Tulpehocken Creek and Walnut Creek watersheds. Sensitivity studies show that whenmore » the spatial variability of topography or recharge, or both is increased, the subsurface flows increase at the two aforementioned sites and the Maimai hillslope. This is likely due to enhancement of interactions between the groundwater table and the land surface that reduce the flow path. An important conclusion of this study is that the spatial variability of recharge alone, and/or in combination with the spatial variability of topography can substantially alter the behaviors of subsurface flows. This suggests that in macroscale hydrologic models or land surface models, subgrid variations of recharge and topography can make significant contributions to the grid mean subsurface flow and must be accounted for in regions with large surface heterogeneity. This is particularly true for regions with humid climate and relatively shallow groundwater table where the combined impacts of spatial variability of recharge and topography are shown to be more important. For regions with arid climate and relatively deep groundwater table, simpler formulations, especially the power law, for subsurface flow can work well, and the impacts of subgrid variations of recharge and topography may be ignored.« less

Modeling Vegetation Growth Impact on Groundwater Recharge

NASA Astrophysics Data System (ADS)

Anurag, H.; Ng, G. H. C.; Tipping, R.

2017-12-01

Vegetation growth is affected by variability in climate and land-cover / land-use over a range of temporal and spatial scales. Vegetation also modifies water budget through interception and evapotranspiration and thus has a significant impact on groundwater recharge. Most groundwater recharge assessments represent vegetation using specified, static parameter, such as for leaf-area-index, but this neglects the effect of vegetation dynamics on recharge estimates. Our study addresses this gap by including vegetation growth in model simulations of recharge. We use NCAR's Community Land Model v4.5 with its BGC module (BGC is the new CLM4.5 biogeochemistry). It integrates prognostic vegetation growth with land-surface and subsurface hydrological processes and can thus capture the effect of vegetation on groundwater. A challenge, however, is the need to resolve uncertainties in model inputs ranging from vegetation growth parameters all the way down to the water table. We have compiled diverse data spanning meteorological inputs to subsurface geology and use these to implement ensemble model simulations to evaluate the possible effects of dynamic vegetation growth (versus specified, static vegetation parameterizations) on estimating groundwater recharge. We present preliminary results for select data-intensive test locations throughout the state of Minnesota (USA), which has a sharp east-west precipitation gradient that makes it an apt testbed for examining ecohydrologic relationships across different temperate climatic settings and ecosystems. Using the ensemble simulations, we examine the effect of seasonal to interannual variability of vegetation growth on recharge and water table depths, which has implications for predicting the combined impact of climate, vegetation, and geology on groundwater resources. Future work will include distributed model simulations over the entire state, as well as conditioning uncertain vegetation and subsurface parameters on remote sensing data and statewide water table records using data assimilation.

Imaging the Subsurface of the Thuringian Basin (Germany) on Different Spatial Scales

NASA Astrophysics Data System (ADS)

Goepel, A.; Krause, M.; Methe, P.; Kukowski, N.

2014-12-01

Understanding the coupled dynamics of near surface and deep fluid flow patterns is essential to characterize the properties of sedimentary basins, to identify the processes of compaction, diagenesis, and transport of mass and energy. The multidisciplinary project INFLUINS (Integrated FLUid dynamics IN Sedimentary basins) aims for investigating the behavior of fluids in the Thuringian Basin, a small intra-continental sedimentary basin in Germany, at different spatial scales, ranging from the pore scale to the extent of the entire basin. As hydraulic properties often significantly vary with spatial scales, e.g. seismic data using different frequencies are required to gain information about the spatial variability of elastic and hydraulic subsurface properties. For the Thuringian Basin, we use seismic and borehole data acquired in the framework of INFLUINS. Basin-wide structural imaging data are available from 2D reflection seismic profiles as well as 2.5D and 3D seismic travel time tomography. Further, core material from a 1,179 m deep drill hole completed in 2013 is available for laboratory seismic experiments on mm- to cm-scale. The data are complemented with logging data along the entire drill hole. This campaign yielded e.g. sonic and density logs allowing the estimation of in-situ P-velocity and acoustic impedance with a spatial resolution on the cm-scale and provides improved information about petrologic and stratigraphic variability at different scales. Joint interpretation of basin scale structural and elastic properties data with laboratory scale data from ultrasound experiments using core samples enables a detailed and realistic imaging of the subsurface properties on different spatial scales. Combining seismic travel time tomography with stratigraphic interpretation provides useful information of variations in the elastic properties for certain geological units and therefore gives indications for changes in hydraulic properties.

Changing spatial patterns of evapotranspiration and deep drainage in response to the interactions among impervious surface arrangement, soil characteristics, and weather on a residential parcel.

NASA Astrophysics Data System (ADS)

Voter, C. B.; Steven, L. I.

2015-12-01

The introduction impervious surfaces in urban areas is a key driver of hydrologic change. It is now well understood that the amount of "effective" impervious area directly connected to the storm sewer network is a better indicator of hydrologic behavior than the total amount of impervious area. Most studies in urban hydrology have focused on the relationship between impervious connectivity and stormwater runoff or other surface water flows, with the result that the effect on subsurface flow is not as well understood. In the field, we observe differences in soil moisture availability that are dependent on proximity to impervious features and significant from a root water uptake perspective, which indicates that parcel-scale subsurface and plant water fluxes may also be sensitive to fine-scaled heterogeneity in impervious surface arrangement and connectivity. We use ParFlow with CLM, a watershed model with fully integrated variably-saturated subsurface flow, overland flow, and land-surface processes, to explore the extent to which soil moisture, evapotranspiration, and deep drainage vary under various impervious surface arrangement and soil condition scenarios, as well as under a range of precipitation regimes. We investigate the effect of several impervious surface and soil characteristics, including general lot layout, downspout disconnect, and direction of driveway/sidewalk slope, and soil compaction. We show that that some impervious connectivity schemes transfer more water from impervious areas to pervious ones and promote localized recharge by developing well-defined, fast-moving wetting fronts that are able to penetrate the root zone. Enhanced infiltration is translated more directly to recharge in normal to wet years but partitioned more often to transpiration in dry years, leading to a nonlinear relationship among precipitation, runoff and recharge.

Demonstration of innovative monitoring technologies at the Savannah River Integrated Demonstration Site

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

Rossabi, J.; Jenkins, R.A.; Wise, M.B.

1993-12-31

The Department of Energy`s Office of Technology Development initiated an Integrated Demonstration Program at the Savannah River Site in 1989. The objective of this program is to develop, demonstrate, and evaluate innovative technologies that can improve present-day environmental restoration methods. The Integrated Demonstration Program at SRS is entitled ``Cleanup of Organics in Soils and Groundwater at Non-Arid Sites.`` New technologies in the areas of drilling, characterization, monitoring, and remediation are being demonstrated and evaluated for their technical performance and cost effectiveness in comparison with baseline technologies. Present site characterization and monitoring methods are costly, time-consuming, overly invasive, and often imprecise.more » Better technologies are required to accurately describe the subsurface geophysical and geochemical features of a site and the nature and extent of contamination. More efficient, nonintrusive characterization and monitoring techniques are necessary for understanding and predicting subsurface transport. More reliable procedures are also needed for interpreting monitoring and characterization data. Site characterization and monitoring are key elements in preventing, identifying, and restoring contaminated sites. The remediation of a site cannot be determined without characterization data, and monitoring may be required for 30 years after site closure.« less

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.

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.

Autonomous microexplosives subsurface tracing system final report.

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

Engler, Bruce Phillip; Nogan, John; Melof, Brian Matthew

The objective of the autonomous micro-explosive subsurface tracing system is to image the location and geometry of hydraulically induced fractures in subsurface petroleum reservoirs. This system is based on the insertion of a swarm of autonomous micro-explosive packages during the fracturing process, with subsequent triggering of the energetic material to create an array of micro-seismic sources that can be detected and analyzed using existing seismic receiver arrays and analysis software. The project included investigations of energetic mixtures, triggering systems, package size and shape, and seismic output. Given the current absence of any technology capable of such high resolution mapping ofmore » subsurface structures, this technology has the potential for major impact on petroleum industry, which spends approximately $1 billion dollar per year on hydraulic fracturing operations in the United States alone.« less

Subsurface conditions in hydrothermal vents inferred from diffuse flow composition, and models of reaction and transport

NASA Astrophysics Data System (ADS)

Larson, B. I.; Houghton, J. L.; Lowell, R. P.; Farough, A.; Meile, C. D.

2015-08-01

Chemical gradients in the subsurface of mid-ocean ridge hydrothermal systems create an environment where minerals precipitate and dissolve and where chemosynthetic organisms thrive. However, owing to the lack of easy access to the subsurface, robust knowledge of the nature and extent of chemical transformations remains elusive. Here, we combine measurements of vent fluid chemistry with geochemical and transport modeling to give new insights into the under-sampled subsurface. Temperature-composition relationships from a geochemical mixing model are superimposed on the subsurface temperature distribution determined using a heat flow model to estimate the spatial distribution of fluid composition. We then estimate the distribution of Gibb's free energies of reaction beneath mid oceanic ridges and by combining flow simulations with speciation calculations estimate anhydrite deposition rates. Applied to vent endmembers observed at the fast spreading ridge at the East Pacific Rise, our results suggest that sealing times due to anhydrite formation are longer than the typical time between tectonic and magmatic events. The chemical composition of the neighboring low temperature flow indicates relatively uniform energetically favorable conditions for commonly inferred microbial processes such as methanogenesis, sulfate reduction and numerous oxidation reactions, suggesting that factors other than energy availability may control subsurface microbial biomass distribution. Thus, these model simulations complement fluid-sample datasets from surface venting and help infer the chemical distribution and transformations in subsurface flow.

Force measurement-based discontinuity detection during friction stir welding

DOE PAGES

Shrivastava, Amber; Zinn, Michael; Duffie, Neil A.; ...

2017-02-23

Here, the objective of this work is to develop a method for detecting the creation of discontinuities ( i.e., voids, volume defects) during friction stir welding. Friction stir welding is inherently cost effective, however, the need for significant weld inspection can make the process cost prohibitive. A new approach to weld inspection is required in which an in situ characterization of weld quality can be obtained, reducing the need for postprocess inspection. To this end, friction stir welds with subsurface voids and without voids were created. The subsurface voids were generated by reducing the friction stir tool rotation frequency andmore » increasing the tool traverse speed in order to create “colder” welds. Process forces were measured during welding, and the void sizes were measured postprocess by computerized tomography ( i.e., 3D X-ray imaging). Two parameters, based on frequency domain content and time-domain average of the force signals, were found to be correlated with void size. Criteria for subsurface void detection and size prediction were developed and shown to be in good agreement with experimental observations. Furthermore, with the proper choice of data acquisition system and frequency analyzer the occurrence of subsurface voids can be detected in real time.« less

Force measurement-based discontinuity detection during friction stir welding

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

Shrivastava, Amber; Zinn, Michael; Duffie, Neil A.

Here, the objective of this work is to develop a method for detecting the creation of discontinuities ( i.e., voids, volume defects) during friction stir welding. Friction stir welding is inherently cost effective, however, the need for significant weld inspection can make the process cost prohibitive. A new approach to weld inspection is required in which an in situ characterization of weld quality can be obtained, reducing the need for postprocess inspection. To this end, friction stir welds with subsurface voids and without voids were created. The subsurface voids were generated by reducing the friction stir tool rotation frequency andmore » increasing the tool traverse speed in order to create “colder” welds. Process forces were measured during welding, and the void sizes were measured postprocess by computerized tomography ( i.e., 3D X-ray imaging). Two parameters, based on frequency domain content and time-domain average of the force signals, were found to be correlated with void size. Criteria for subsurface void detection and size prediction were developed and shown to be in good agreement with experimental observations. Furthermore, with the proper choice of data acquisition system and frequency analyzer the occurrence of subsurface voids can be detected in real time.« less

3D numerical modeling of hyporheic exchange processes in fractal riverbed

NASA Astrophysics Data System (ADS)

Lee, A.; Aubeneau, A.

2017-12-01

The subsurface region receiving stream water is known as the hyporheic zone and the flow of water in and out of this zone is called hyporheic exchange. The hyporheic zone is populated by biofilms and is a hotspot for nutrient uptake and contaminant transformation. Traditionally, pumping models predicting the head distribution over the riverbed boundary are used to obtain the velocity field in the subsurface. However, past research has largely overlooked the nonlinearity of the turbulent flow above the bumpy riverbed. The main objective of this research is to investigate the effect of spatial and temporal heterogeneity created by turbulent flow on hyporheic exchange and residence time distribution in fractal channel beds. The 3-D fractal riverbed is created from the power spectrum. Large-Eddy Simulation is used to provide the pressure field over the benthic boundary. Finally, Darcian fluxes in the sub-surface are calculated and hyporheic travel times computed using random walks. Surface and subsurface transport processes are represented explicitly and can be studied in detail. Our results suggest that (1) Eddies and wakes around the dunes force the exchange (2) The bigger the dunes, the greater the influence of turbulence (3) Turbulence induces more exchange than pumping predicts.

Recruitment from an egg bank into the plankton in Baisha Bay, a mariculture base in Southern China

NASA Astrophysics Data System (ADS)

Wang, Qing; Luan, Lei-Lei; Chen, Liang-Dong; Yuan, Dan-Ni; Liu, Sheng; Hwang, Jiang-Shiou; Yang, Yu-Feng

2016-11-01

The potential recruitment of resting eggs of calanoid copepods and rotifers to planktonic populations was investigated in the surface and sub-surface sediments of three mariculture zones: an integrated seaweed Gracilaria lemaneiformis and shellfish cultivation area (G), a fish cultivation area (F), and a shellfish cultivation area (S), as well as the sediments of a nearby control sea area (C) in a mariculture base in Southern China. The potential recruitment of copepod and rotifer eggs in the sediments of C and G was significantly higher than in F and S. Potential recruitment in the sub-surface sediments of F and S was not observed, suggesting that fish and shellfish mariculture may be responsible for this decrease. The hatching success of resting eggs of copepods and rotifers was affected by mariculture type, and that large-scale seaweed cultivation may offset the adverse effect of fish and shellfish cultivation on the resting eggs if integrated cultivation is adopted.

Modelling rapid subsurface flow at the hillslope scale with explicit representation of preferential flow paths

NASA Astrophysics Data System (ADS)

Wienhöfer, J.; Zehe, E.

2012-04-01

Rapid lateral flow processes via preferential flow paths are widely accepted to play a key role for rainfall-runoff response in temperate humid headwater catchments. A quantitative description of these processes, however, is still a major challenge in hydrological research, not least because detailed information about the architecture of subsurface flow paths are often impossible to obtain at a natural site without disturbing the system. Our study combines physically based modelling and field observations with the objective to better understand how flow network configurations influence the hydrological response of hillslopes. The system under investigation is a forested hillslope with a small perennial spring at the study area Heumöser, a headwater catchment of the Dornbirnerach in Vorarlberg, Austria. In-situ points measurements of field-saturated hydraulic conductivity and dye staining experiments at the plot scale revealed that shrinkage cracks and biogenic macropores function as preferential flow paths in the fine-textured soils of the study area, and these preferential flow structures were active in fast subsurface transport of artificial tracers at the hillslope scale. For modelling of water and solute transport, we followed the approach of implementing preferential flow paths as spatially explicit structures of high hydraulic conductivity and low retention within the 2D process-based model CATFLOW. Many potential configurations of the flow path network were generated as realisations of a stochastic process informed by macropore characteristics derived from the plot scale observations. Together with different realisations of soil hydraulic parameters, this approach results in a Monte Carlo study. The model setups were used for short-term simulation of a sprinkling and tracer experiment, and the results were evaluated against measured discharges and tracer breakthrough curves. Although both criteria were taken for model evaluation, still several model setups produced acceptable matches to the observed behaviour. These setups were selected for long-term simulation, the results of which were compared against water level measurements at two piezometers along the hillslope and the integral discharge response of the spring to reject some non-behavioural model setups and further reduce equifinality. The results of this study indicate that process-based modelling can provide a means to distinguish preferential flow networks on the hillslope scale when complementary measurements to constrain the range of behavioural model setups are available. These models can further be employed as a virtual reality to investigate the characteristics of flow path architectures and explore effective parameterisations for larger scale applications.

Exploring landscapes and ecosystems by studying their streams

NASA Astrophysics Data System (ADS)

Kirchner, J. W.

2016-12-01

Streams integrate fluxes of water, solutes, and sediment from their catchments, and thus they act as mirrors of the surrounding landscape. Patterns of streamflow, chemistry, and sediment flux can therefore shed light on physical, chemical, and biological processes at the scale of whole ecosystems. However, landscapes also exhibit preferential flow and pervasive heterogeneity on all scales, and therefore store waters over a wide spectrum of time scales, complicating efforts to interpret hydrological and geochemical signals in streamwaters. Here I review current and recent research exploring how landscapes store, mix, and release water and solutes to streams. Groundwater levels and stream flows exhibit diurnal cycles in response to snowmelt in springtime and transpiration during the growing season. These cycles vividly illustrate how aquifers and streams mirror ecological processes in their surrounding landscapes. Stream networks extend and retract, both seasonally and in response to individual rainfall events, dynamically mapping out variations in subsurface transmissivity and in the balance between precipitation and transpiration. Water quality time series spanning the periodic table, from H+ to U, exhibit universal fractal scaling on time scales from hours to decades. This scaling behavior is a temporal expression of the spatial heterogeneity that pervades the subsurface, and it confounds efforts to identify water quality trends. Isotope tracers such as 18O, 2H, 3H, and 14C can used to quantify water ages over seven orders of magnitude, from hours to thousands of years. These tracers show that substantial fractions of streamflow are hours, days, and months old, even in streams fed by aquifers with significant proportions of pre-Holocene groundwater. Examples such as these will be presented to illustrate the close coupling between landscapes and the waters that drain them, and to demonstrate how streams can be used as windows into landscape processes.

Use of an optical clearing agent to enhance the visibility of subsurface structures and lesions from tooth occlusal surfaces

NASA Astrophysics Data System (ADS)

Kang, Hobin; Darling, Cynthia L.; Fried, Daniel

2016-08-01

The purpose of this study is to show that optical clearing agents can be used to increase the visibility of deeply penetrating occlusal lesions that have reached the underlying dentin and spread laterally under the enamel. Previous studies have shown that high refractive index fluids can increase the contrast of caries lesions. Extracted teeth with natural occlusal lesions were imaged with optical coherence tomography (OCT) with and without the addition of a transparent vinyl polysiloxane impression material (VPS) currently used in vivo. The relative intensity of the reflectivity from the underlying lesion area for each sample was measured before and after application of the VPS. Lesion presence was confirmed with polarized light microscopy and microradiography. Application of VPS significantly increased (P<0.0001) the integrated reflectivity of subsurface dentinal lesions. This study shows that optical clearing agents can be used to increase the optical penetration and the visibility of subsurface lesions and the dentinal-enamel junction under sound and demineralized enamel in OCT images.

Fiber Optic Bragg Grating Sensors for Thermographic Detection of Subsurface Anomalies

NASA Technical Reports Server (NTRS)

Allison, Sidney G.; Winfree, William P.; Wu, Meng-Chou

2009-01-01

Conventional thermography with an infrared imager has been shown to be an extremely viable technique for nondestructively detecting subsurface anomalies such as thickness variations due to corrosion. A recently developed technique using fiber optic sensors to measure temperature holds potential for performing similar inspections without requiring an infrared imager. The structure is heated using a heat source such as a quartz lamp with fiber Bragg grating (FBG) sensors at the surface of the structure to detect temperature. Investigated structures include a stainless steel plate with thickness variations simulated by small platelets attached to the back side using thermal grease. A relationship is shown between the FBG sensor thermal response and variations in material thickness. For comparison, finite element modeling was performed and found to agree closely with the fiber optic thermography results. This technique shows potential for applications where FBG sensors are already bonded to structures for Integrated Vehicle Health Monitoring (IVHM) strain measurements and can serve dual-use by also performing thermographic detection of subsurface anomalies.

Assessment of groundwater potentiality using geophysical techniques in Wadi Allaqi basin, Eastern Desert, Egypt - Case study

NASA Astrophysics Data System (ADS)

Helaly, Ahmad Sobhy

2017-12-01

Electrical resistivity surveying has been carried out for the determination of the thickness and resistivity of layered media in Wadi Allaqi, Eastern Desert, Egypt. That is widely used geophysical tool for the purpose of assessing the groundwater potential and siting the best locations for boreholes in the unconfined Nubian Sandstone aquifers within the study area. This has been done using thirteen 1D Vertical Electrical Sounding (VES) surveys. 1D-VES surveys provide only layered model structures for the subsurface and do not provide comprehensive information for interpreting the structure and extent of subsurface hydro-geological features. The integration of two-dimensional (2D) geophysical techniques for groundwater prospecting has been done to provide a more detailed identification for the subsurface hydro-geological features from which potential sites for successful borehole locations are recognized. In addition, five magnetic profiles were measured for basement depth determination, expected geological structures and thickness of sedimentary succession that could include some basins suitable for groundwater accumulation as groundwater aquifers.

Advanced Algorithms and High-Performance Testbed for Large-Scale Site Characterization and Subsurface Target Detecting Using Airborne Ground Penetrating SAR

NASA Technical Reports Server (NTRS)

Fijany, Amir; Collier, James B.; Citak, Ari

1997-01-01

A team of US Army Corps of Engineers, Omaha District and Engineering and Support Center, Huntsville, let Propulsion Laboratory (JPL), Stanford Research Institute (SRI), and Montgomery Watson is currently in the process of planning and conducting the largest ever survey at the Former Buckley Field (60,000 acres), in Colorado, by using SRI airborne, ground penetrating, Synthetic Aperture Radar (SAR). The purpose of this survey is the detection of surface and subsurface Unexploded Ordnance (UXO) and in a broader sense the site characterization for identification of contaminated as well as clear areas. In preparation for such a large-scale survey, JPL has been developing advanced algorithms and a high-performance restbed for processing of massive amount of expected SAR data from this site. Two key requirements of this project are the accuracy (in terms of UXO detection) and speed of SAR data processing. The first key feature of this testbed is a large degree of automation and a minimum degree of the need for human perception in the processing to achieve an acceptable processing rate of several hundred acres per day. For accurate UXO detection, novel algorithms have been developed and implemented. These algorithms analyze dual polarized (HH and VV) SAR data. They are based on the correlation of HH and VV SAR data and involve a rather large set of parameters for accurate detection of UXO. For each specific site, this set of parameters can be optimized by using ground truth data (i.e., known surface and subsurface UXOs). In this paper, we discuss these algorithms and their successful application for detection of surface and subsurface anti-tank mines by using a data set from Yuma proving Ground, A7, acquired by SRI SAR.

Fast history matching of time-lapse seismic and production data for high resolution models

NASA Astrophysics Data System (ADS)

Jimenez Arismendi, Eduardo Antonio

Integrated reservoir modeling has become an important part of day-to-day decision analysis in oil and gas management practices. A very attractive and promising technology is the use of time-lapse or 4D seismic as an essential component in subsurface modeling. Today, 4D seismic is enabling oil companies to optimize production and increase recovery through monitoring fluid movements throughout the reservoir. 4D seismic advances are also being driven by an increased need by the petroleum engineering community to become more quantitative and accurate in our ability to monitor reservoir processes. Qualitative interpretations of time-lapse anomalies are being replaced by quantitative inversions of 4D seismic data to produce accurate maps of fluid saturations, pore pressure, temperature, among others. Within all steps involved in this subsurface modeling process, the most demanding one is integrating the geologic model with dynamic field data, including 4Dseismic when available. The validation of the geologic model with observed dynamic data is accomplished through a "history matching" (HM) process typically carried out with well-based measurements. Due to low resolution of production data, the validation process is severely limited in its reservoir areal coverage, compromising the quality of the model and any subsequent predictive exercise. This research will aim to provide a novel history matching approach that can use information from high-resolution seismic data to supplement the areally sparse production data. The proposed approach will utilize streamline-derived sensitivities as means of relating the forward model performance with the prior geologic model. The essential ideas underlying this approach are similar to those used for high-frequency approximations in seismic wave propagation. In both cases, this leads to solutions that are defined along "streamlines" (fluid flow), or "rays" (seismic wave propagation). Synthetic and field data examples will be used extensively to demonstrate the value and contribution of this work. Our results show that the problem of non-uniqueness in this complex history matching problem is greatly reduced when constraints in the form of saturation maps from spatially closely sampled seismic data are included. Further on, our methodology can be used to quickly identify discrepancies between static and dynamic modeling. Reducing this gap will ensure robust and reliable models leading to accurate predictions and ultimately an optimum hydrocarbon extraction.

Akuna: An Open Source User Environment for Managing Subsurface Simulation Workflows

NASA Astrophysics Data System (ADS)

Freedman, V. L.; Agarwal, D.; Bensema, K.; Finsterle, S.; Gable, C. W.; Keating, E. H.; Krishnan, H.; Lansing, C.; Moeglein, W.; Pau, G. S. H.; Porter, E.; Scheibe, T. D.

2014-12-01

The U.S. Department of Energy (DOE) is investing in development of a numerical modeling toolset called ASCEM (Advanced Simulation Capability for Environmental Management) to support modeling analyses at legacy waste sites. ASCEM is an open source and modular computing framework that incorporates new advances and tools for predicting contaminant fate and transport in natural and engineered systems. The ASCEM toolset includes both a Platform with Integrated Toolsets (called Akuna) and a High-Performance Computing multi-process simulator (called Amanzi). The focus of this presentation is on Akuna, an open-source user environment that manages subsurface simulation workflows and associated data and metadata. In this presentation, key elements of Akuna are demonstrated, which includes toolsets for model setup, database management, sensitivity analysis, parameter estimation, uncertainty quantification, and visualization of both model setup and simulation results. A key component of the workflow is in the automated job launching and monitoring capabilities, which allow a user to submit and monitor simulation runs on high-performance, parallel computers. Visualization of large outputs can also be performed without moving data back to local resources. These capabilities make high-performance computing accessible to the users who might not be familiar with batch queue systems and usage protocols on different supercomputers and clusters.

Spatial Distribution of an Uranium-Respiring Betaproteobacterium at the Rifle, CO Field Research Site

PubMed Central

Koribanics, Nicole M.; Tuorto, Steven J.; Lopez-Chiaffarelli, Nora; McGuinness, Lora R.; Häggblom, Max M.; Williams, Kenneth H.; Long, Philip E.; Kerkhof, Lee J.

2015-01-01

The Department of Energy’s Integrated Field-Scale Subsurface Research Challenge Site (IFRC) at Rifle, Colorado was created to address the gaps in knowledge on the mechanisms and rates of U(VI) bioreduction in alluvial sediments. Previous studies at the Rifle IFRC have linked microbial processes to uranium immobilization during acetate amendment. Several key bacteria believed to be involved in radionuclide containment have been described; however, most of the evidence implicating uranium reduction with specific microbiota has been indirect. Here, we report on the cultivation of a microorganism from the Rifle IFRC that reduces uranium and appears to utilize it as a terminal electron acceptor for respiration with acetate as electron donor. Furthermore, this bacterium constitutes a significant proportion of the subsurface sediment community prior to biostimulation based on TRFLP profiling of 16S rRNA genes. 16S rRNA gene sequence analysis indicates that the microorganism is a betaproteobacterium with a high similarity to Burkholderia fungorum. This is, to our knowledge, the first report of a betaproteobacterium capable of uranium respiration. Our results indicate that this microorganism occurs commonly in alluvial sediments located between 3-6 m below ground surface at Rifle and may play a role in the initial reduction of uranium at the site. PMID:25874721

Spatial distribution of an uranium-respiring betaproteobacterium at the Rifle, CO field research site

DOE PAGES

Koribanics, Nicole M.; Tuorto, Steven J.; Lopez-Chiaffarelli, Nora; ...

2015-04-13

The Department of Energy’s Integrated Field-Scale Subsurface Research Challenge Site (IFRC) at Rifle, Colorado was created to address the gaps in knowledge on the mechanisms and rates of U(VI) bioreduction in alluvial sediments. Previous studies at the Rifle IFRC have linked microbial processes to uranium immobilization during acetate amendment. Several key bacteria believed to be involved in radionuclide containment have been described; however, most of the evidence implicating uranium reduction with specific microbiota has been indirect. Here, we report on the cultivation of a microorganism from the Rifle IFRC that reduces uranium and appears to utilize it as a terminalmore » electron acceptor for respiration with acetate as electron donor. Furthermore, this bacterium constitutes a significant proportion of the subsurface sediment community prior to biostimulation based on TRFLP profiling of 16S rRNA genes. 16S rRNA gene sequence analysis indicates that the microorganism is a betaproteobacterium with a high similarity to Burkholderia fungorum. This is, to our knowledge, the first report of a betaproteobacterium capable of uranium respiration. Our results indicate that this microorganism occurs commonly in alluvial sediments located between 3-6 m below ground surface at Rifle and may play a role in the initial reduction of uranium at the site.« less

Monitoring remineralization of enamel subsurface lesions by optical coherence tomography

NASA Astrophysics Data System (ADS)

Mandurah, Mona M.; Sadr, Alireza; Shimada, Yasushi; Kitasako, Yuichi; Nakashima, Syozi; Bakhsh, Turki A.; Tagami, Junji; Sumi, Yasunori

2013-04-01

Optical coherence tomography (OCT) is a potential clinical tool for enamel lesion monitoring. Swept-source OCT findings were compared with cross-sectional nanohardness findings of enamel. Subsurface bovine enamel lesions in three groups were subjected to (1) deionized water (control), (2) phosphoryl oligosaccharide of calcium (POs-Ca) or (3) POs-Ca with 1 ppm fluoride for 14 days. B-scans images were obtained at 1310-nm center wavelength on sound, demineralized and remineralized areas after 4, 7, and 14 days. The specimens were processed for cross-sectional nanoindentation. Reflectivity from enamel that had increased with demineralization decreased with remineralization. An OCT attenuation coefficient parameter (μt), derived based on the Beer-Lambert law as a function of backscatter signal slope, showed a strong linear regression with integrated nanohardness of all regions (p<0.001, r=-0.97). Sound enamel showed the smallest, while demineralized enamel showed the highest μt. In group three, μt was significantly lower at four days than baseline, but remained constant afterwards. In group two, the changes were rather gradual. There was no significant difference between groups two and three at 14 days in nanohardness or μt POs-Ca with fluoride-enhanced nanohardness of the superficial zone. OCT signal attenuation demonstrated a capability for monitoring changes of enamel lesions during remineralization.

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.

Sour gas injection for use with in situ heat treatment

DOEpatents

Fowler, Thomas David [Houston, TX

2009-11-03

Systems, methods, and heaters for treating a subsurface formation are described herein. At least one method for providing acidic gas to a subsurface formation is described herein. The method may include providing heat from one or more heaters to a portion of a subsurface formation; producing fluids that include one or more acidic gases from the formation using a heat treatment process. At least a portion of one of the acidic gases may be introduced into the formation, or into another formation, through one or more wellbores at a pressure below a lithostatic pressure of the formation in which the acidic gas is introduced.

Methods of producing transportation fuel

DOEpatents

Nair, Vijay [Katy, TX; Roes, Augustinus Wilhelmus Maria [Houston, TX; Cherrillo, Ralph Anthony [Houston, TX; Bauldreay, Joanna M [Chester, GB

2011-12-27

Systems, methods, and heaters for treating a subsurface formation are described herein. At least one method for producing transportation fuel is described herein. The method for producing transportation fuel may include providing formation fluid having a boiling range distribution between -5.degree. C. and 350.degree. C. from a subsurface in situ heat treatment process to a subsurface treatment facility. A liquid stream may be separated from the formation fluid. The separated liquid stream may be hydrotreated and then distilled to produce a distilled stream having a boiling range distribution between 150.degree. C. and 350.degree. C. The distilled liquid stream may be combined with one or more additives to produce transportation fuel.

Lifetime prediction for the subsurface crack propagation using three-dimensional dynamic FEA model

NASA Astrophysics Data System (ADS)

Yin, Yuan; Chen, Yun-Xia; Liu, Le

2017-03-01

The subsurface crack propagation is one of the major interests for gear system research. The subsurface crack propagation lifetime is the number of cycles remaining for a spall to appear, which can be obtained through either stress intensity factor or accumulated plastic strain analysis. In this paper, the heavy loads are applied to the gear system. When choosing stress intensity factor, the high compressive stress suppresses Mode I stress intensities and severely reduces Mode II stress intensities in the heavily loaded lubricated contacts. Such that, the accumulated plastic strain is selected to calculate the subsurface crack propagation lifetime from the three-dimensional FEA model through ANSYS Workbench transient analysis. The three-dimensional gear FEA dynamic model with the subsurface crack is built through dividing the gears into several small elements. The calculation of the total cycles of the elements is proposed based on the time-varying accumulated plastic strain, which then will be used to calculate the subsurface crack propagation lifetime. During this process, the demonstration from a subsurface crack to a spall can be uncovered. In addition, different sizes of the elements around the subsurface crack are compared in this paper. The influences of the frictional coefficient and external torque on the crack propagation lifetime are also discussed. The results show that the lifetime of crack propagation decreases significantly when the external load T increasing from 100 N m to 150 N m. Given from the distributions of the accumulated plastic strain, the lifetime shares no significant difference when the frictional coefficient f ranging in 0.04-0.06.

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.

Microbial production and oxidation of methane in deep subsurface

NASA Astrophysics Data System (ADS)

Kotelnikova, Svetlana

2002-10-01

The goal of this review is to summarize present studies on microbial production and oxidation of methane in the deep subterranean environments. Methane is a long-living gas causing the "greenhouse" effect in the planet's atmosphere. Earlier, the deep "organic carbon poor" subsurface was not considered as a source of "biogenic" methane. Evidence of active methanogenesis and presence of viable methanogens including autotrophic organisms were obtained for some subsurface environments including water-flooded oil-fields, deep sandy aquifers, deep sea hydrothermal vents, the deep sediments and granitic groundwater at depths of 10 to 2000 m below sea level. As a rule, the deep subterranean microbial populations dwell at more or less oligotrophic conditions. Molecular hydrogen has been found in a variety of subsurface environments, where its concentrations were significantly higher than in the tested surface aquatic environments. Chemolithoautotrophic microorganisms from deep aquifers that could grow on hydrogen and carbon dioxide can act as primary producers of organic carbon, initiating heterotrophic food chains in the deep subterranean environments independent of photosynthesis. "Biogenic" methane has been found all over the world. On the basis of documented occurrences, gases in reservoirs and older sediments are similar and have the isotopic character of methane derived from CO 2 reduction. Groundwater representing the methanogenic end member are characterized by a relative depletion of dissolved organic carbon (DOC) in combination with an enrichment in 13C in inorganic carbon, which is consistent with the preferential reduction of 12CO 2 by autotrophic methanogens or acetogens. The isotopic composition of methane formed via CO 2 reduction is controlled by the δ13C of the original CO 2 substrate. Literature data shows that CH 4 as heavy as -40‰ or -50‰ can be produced by the microbial reduction of isotopically heavy CO 2. Produced methane may be oxidized microbially to carbon dioxide. Microbial methane oxidation is a biogeochemical process that limits the release of methane, a greenhouse gas from anaerobic environments. Anaerobic methane oxidation plays an important role in marine sediments. Similar processes may take place in deep subsurface and thus fuel the deep microbial community. Organisms or consortia responsible for anaerobic methane oxidation have not yet been cultured, although diverse aerobic methanotrophs have been isolated from a variety of underground niches. The presence of aerobic methanotrophs in the anoxic subsurface remains to be explained. The presence of methane in the deep subsurface have been shown all over the world. The flux of gases between the deep subsurface and the atmosphere is driven by the concentration gradient from depth to the atmosphere. However, methane is consumed by methanotrophs on the way of its evolution in oxidized environments and is transformed to organic form, available for further microbial processing. When the impact of subsurface environments to global warming is estimated, it is necessary to take into account the activity of methane-producing Archaea and methane-oxidizing biofilters in groundwater. Microbial production and oxidation of methane is involved in the carbon cycle in the deep subsurface environments.

Río Tinto Faulted Volcanosedimentary Deposits as Analog Habitats for Extant Subsurface Biospheres on Mars: A Synthesis of the MARTE Drilling Project Geobiology Results

NASA Astrophysics Data System (ADS)

Fernández-Remolar, D. C.; Prieto-Ballesteros, O.; Rodríguez, N.; Dávila, F.; Stevens, T.; Amils, R.; Gómez-Elvira, J.; Stoker, C. R.

2005-03-01

Reconstruction of the probable habitats hosting the detected microbial communities through the integration of the geobiological data obtained from the MARTE drilling campaigns, TEM sounding and field surface geological survey

Implementationof a modular software system for multiphysical processes in porous media

NASA Astrophysics Data System (ADS)

Naumov, Dmitri; Watanabe, Norihiro; Bilke, Lars; Fischer, Thomas; Lehmann, Christoph; Rink, Karsten; Walther, Marc; Wang, Wenqing; Kolditz, Olaf

2016-04-01

Subsurface georeservoirs are a candidate technology for large scale energy storage required as part of the transition to renewable energy sources. The increased use of the subsurface results in competing interests and possible impacts on protected entities. To optimize and plan the use of the subsurface in large scale scenario analyses,powerful numerical frameworks are required that aid process understanding and can capture the coupled thermal (T), hydraulic (H), mechanical (M), and chemical (C) processes with high computational efficiency. Due to having a multitude of different couplings between basic T, H, M, or C processes and the necessity to implement new numerical schemes the development focus has moved to software's modularity. The decreased coupling between the components results in two major advantages: easier addition of specialized processes and improvement of the code's testability and therefore its quality. The idea of modularization is implemented on several levels, in addition to library based separation of the previous code version, by using generalized algorithms available in the Standard Template Library and the Boost library, relying on efficient implementations of liner algebra solvers, using concepts when designing new types, and localization of frequently accessed data structures. This procedure shows certain benefits for a flexible high-performance framework applied to the analysis of multipurpose georeservoirs.

Sensitivity of transpiration to subsurface properties: Exploration with a 1-D model

NASA Astrophysics Data System (ADS)

Vrettas, Michail D.; Fung, Inez Y.

2017-06-01

The amount of moisture transpired by vegetation is critically tied to the moisture supply accessible to the root zone. In a Mediterranean climate, integrated evapotranspiration (ET) is typically greater in the dry summer when there is an uninterrupted period of high insolation. We present a 1-D model to explore the subsurface factors that may sustain ET through the dry season. The model includes a stochastic parameterization of hydraulic conductivity, root water uptake efficiency, and hydraulic redistribution by plant roots. Model experiments vary the precipitation, the magnitude and seasonality of ET demand, as well as rooting profiles and rooting depths of the vegetation. The results show that the amount of subsurface moisture remaining at the end of the wet winter is determined by the competition among abundant precipitation input, fast infiltration, and winter ET demand. The weathered bedrock retains ˜30% of the winter rain and provides a substantial moisture reservoir that may sustain ET of deep-rooted (>8 m) trees through the dry season. A small negative feedback exists in the root zone, where the depletion of moisture by ET decreases hydraulic conductivity and enhances the retention of moisture. Hence, hydraulic redistribution by plant roots is impactful in a dry season, or with a less conductive subsurface. Suggestions for implementing the model in the CESM are discussed.

Beneath the surface: Characteristics of oceanic ecosystems under weak mixing conditions A theoretical investigation

NASA Astrophysics Data System (ADS)

Beckmann, Aike; Hense, Inga

2007-12-01

This study considers an important biome in aquatic environments, the subsurface ecosystem that evolves under low mixing conditions, from a theoretical point of view. Employing a conceptual model that involves phytoplankton, a limiting nutrient and sinking detritus, we use a set of key characteristics (thickness, depth, biomass amplitude/productivity) to qualitatively and quantitatively describe subsurface biomass maximum layers (SBMLs) of phytoplankton. These SBMLs are defined by the existence of two community compensation depths in the water column, which confine the layer of net community production; their depth coincides with the upper nutricline. Analysing the results of a large ensemble of simulations with a one-dimensional numerical model, we explore the parameter dependencies to obtain fundamental steady-state relationships that connect primary production, mortality and grazing, remineralization, vertical diffusion and detrital sinking. As a main result, we find that we can distinguish between factors that determine the vertically integrated primary production and others that affect only depth and shape (thickness and biomass amplitude) of this subsurface production layer. A simple relationship is derived analytically, which can be used to estimate the steady-state primary productivity in the subsurface oligotrophic ocean. The fundamental nature of the results provides further insight into the dynamics of these “hidden” ecosystems and their role in marine nutrient cycling.

Surface Penetrating Radar Simulations for Europa

NASA Technical Reports Server (NTRS)

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

2004-01-01

The space environment above the icy surface of Europa is a source of radio noise in this frequency range from natural sources in the Jovian magnetosphere. The ionospheric and magnetospheric plasma environment of Europa affects propagation of transmitted and return signals between the spacecraft and the solid surface in a frequency-dependent manner. The ultimate resolution of the subsurface sounding measurements will be determined, in part, by a capability to mitigate these effects. We discuss an integrated multi-frequency approach to active radio sounding of the Europa ionospheric and local magnetospheric environments, based on operational experience from the Radio Plasma Imaging @PI) experiment on the IMAGE spacecraft in Earth orbit, in support of the subsurface measurement objectives.

Improving Vintage Seismic Data Quality through Implementation of Advance Processing Techniques

NASA Astrophysics Data System (ADS)

Latiff, A. H. Abdul; Boon Hong, P. G.; Jamaludin, S. N. F.

2017-10-01

It is essential in petroleum exploration to have high resolution subsurface images, both vertically and horizontally, in uncovering new geological and geophysical aspects of our subsurface. The lack of success may have been from the poor imaging quality which led to inaccurate analysis and interpretation. In this work, we re-processed the existing seismic dataset with an emphasis on two objectives. Firstly, to produce a better 3D seismic data quality with full retention of relative amplitudes and significantly reduce seismic and structural uncertainty. Secondly, to facilitate further prospect delineation through enhanced data resolution, fault definitions and events continuity, particularly in syn-rift section and basement cover contacts and in turn, better understand the geology of the subsurface especially in regard to the distribution of the fluvial and channel sands. By adding recent, state-of-the-art broadband processing techniques such as source and receiver de-ghosting, high density velocity analysis and shallow water de-multiple, the final results produced a better overall reflection detail and frequency in specific target zones, particularly in the deeper section.

Potential role of resurfacing Subtropical Underwater in ENSO evolution

NASA Astrophysics Data System (ADS)

Qu, T.; Chi, J.

2017-12-01

Results from a model of the Estimating the Circulation and Climate of the Ocean (ECCO) have shown that the resurfacing of high salinity Subtropical Underwater contributes to the sea surface salinity variability in the equatorial Pacific. On interannual time scale, this contribution can account for as much as 25% of the surface freshwater flux anomalies and is believed to play a role in ENSO evolution. Having these results in mind, this study investigates the surface salinity budget and its primary controls in the equatorial Pacific using ECCO output for the period 1993-2016. Particular attention is paid to 2014/2015 and 2015/2016. Preliminary analyses of the model results suggest that enhanced subsurface processes and in particular enhanced entrainment of Subtropical Underwater are primarily responsible for the positive sea surface salinity anomalies in the central equatorial Pacific during 2014/2015, which represents an opposite phase of El Niño. These subsurface processes weakened during 2015/2016, diretly contributing to the development of the 2015/2016 El Niño. The mechanisms controlling these subsurface processes are discussed.

Nontoxic chemical process for in situ permeability enhancement and accelerated decontamination of fine-grain subsurface sediments

DOEpatents

Kansa, E.J.; Wijesinghe, A.M.; Viani, B.E.

1997-01-14

The remediation of heterogeneous subsurfaces is extremely time consuming and expensive with current and developing technologies. Although such technologies can adequately remove contaminants in the high hydraulic conductivity, coarse-grained sediments, they cannot access the contaminated low hydraulic conductivity fine-grained sediments. The slow bleed of contaminants from the fine-grained sediments is the primary reason why subsurface remediation is so time-consuming and expensive. This invention addresses the problem of remediating contaminated fine-grained sediments. It is intended that, in the future, a heterogeneous site be treated by a hybrid process that first remediates the high hydraulic conductivity, coarse-grained sediments, to be followed by the process, described in this invention, to treat the contaminated low hydraulic conductivity fine-grained sediments. The invention uses cationic flocculants and organic solvents to collapse the swelling negative double layer surrounding water saturated clay particles, causing a flocculated, cracked clay structure. The modification of the clay fabric in fine-grained sediments dramatically increases the hydraulic conductivity of previously very tight clays many orders of magnitude. 8 figs.

Nontoxic chemical process for in situ permeability enhancement and accelerated decontamination of fine-grain subsurface sediments

DOEpatents

Kansa, Edward J.; Wijesinghe, Ananda M.; Viani, Brian E.

1997-01-01

The remediation of heterogeneous subsurfaces is extremely time consuming and expensive with current and developing technologies. Although such technologies can adequately remove contaminants in the high hydraulic conductivity, coarse-grained sediments, they cannot access the contaminated low hydraulic conductivity fine-grained sediments. The slow bleed of contaminants from the fine-grained sediments is the primary reason why subsurface remediation is so time-consuming and expensive. This invention addresses the problem of remediating contaminated fine-grained sediments. It is intended that, in the future, a heterogeneous site be treated by a hybrid process that first remediates the high hydraulic conductivity, coarse-grained sediments, to be followed by the process, described in this invention, to treat the contaminated low hydraulic conductivity fine-grained sediments. The invention uses cationic flocculents and organic solvents to collapse the swelling negative double layer surrounding water saturated clay particles, causing a flocculated, cracked clay structure. The modification of the clay fabric in fine-grained sediments dramatically increases the hydraulic conductivity of previously very tight clays many orders of magnitude.

High spatial-temporal resolution and integrated surface and subsurface precipitation-runoff modelling for a small stormwater catchment

NASA Astrophysics Data System (ADS)

Hailegeorgis, Teklu T.; Alfredsen, Knut

2018-02-01

Reliable runoff estimation is important for design of water infrastructure and flood risk management in urban catchments. We developed a spatially distributed Precipitation-Runoff (P-R) model that explicitly represents the land cover information, performs integrated modelling of surface and subsurface components of the urban precipitation water cycle and flow routing. We conducted parameter calibration and validation for a small (21.255 ha) stormwater catchment in Trondheim City during Summer-Autumn events and season, and snow-influenced Winter-Spring seasons at high spatial and temporal resolutions of respectively 5 m × 5 m grid size and 2 min. The calibration resulted in good performance measures (Nash-Sutcliffe efficiency, NSE = 0.65-0.94) and acceptable validation NSE for the seasonal and snow-influenced periods. The infiltration excess surface runoff dominates the peak flows while the contribution of subsurface flow to the sewer pipes also augments the peak flows. Based on the total volumes of simulated flow in sewer pipes (Qsim) and precipitation (P) during the calibration periods, the Qsim/P ranges from 21.44% for an event to 56.50% for the Winter-Spring season, which are in close agreement with the observed volumes (Qobs/P). The lowest percentage of precipitation volume that is transformed to the total simulated runoff in the catchment (QT) is 79.77%. Computation of evapotranspiration (ET) indicated that the ET/P is less than 3% for the events and snow-influenced seasons while it is about 18% for the Summer-Autumn season. The subsurface flow contribution to the sewer pipes are markedly higher than the total surface runoff volume for some events and the Summer-Autumn season. The peakiest flow rates correspond to the Winter-Spring season. Therefore, urban runoff simulation for design and management purposes should include two-way interactions between the subsurface runoff and flow in sewer pipes, and snow-influenced seasons. The developed urban P-R model is useful for better computation of runoff generated from different land cover, for assessments of stormwater management techniques (e.g. the Low Impact Development or LID) and the impacts of land cover and climate change. There are some simplifications or limitations such as the runoff routing does not involve detailed sewer hydraulics, effects of leakages from water supply systems and faulty/illegal connections from sanitary sewer are not considered, the model cannot identify actual locations of the interactions between the subsurface runoff and sewer pipes and lacks parsimony.

Structure and function of subsurface microbial communities affecting radionuclide transport and bioimmobilization

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

Kostka, Joel E.; Prakash, Om; Green, Stefan J.

2012-05-01

Our objectives were to: 1) isolate and characterize novel anaerobic prokaryotes from subsurface environments exposed to high levels of mixed contaminants (U(VI), nitrate, sulfate), 2) elucidate the diversity and distribution of metabolically active metal- and nitrate-reducing prokaryotes in subsurface sediments, and 3) determine the biotic and abiotic mechanisms linking electron transport processes (nitrate, Fe(III), and sulfate reduction) to radionuclide reduction and immobilization. Mechanisms of electron transport and U(VI) transformation were examined under near in situ conditions in sediment microcosms and in field investigations. Field sampling was conducted at the Oak Ridge Field Research Center (ORFRC), in Oak Ridge, Tennessee. Themore » ORFRC subsurface is exposed to mixed contamination predominated by uranium and nitrate. In short, we effectively addressed all 3 stated objectives of the project. In particular, we isolated and characterized a large number of novel anaerobes with a high bioremediation potential that can be used as model organisms, and we are now able to quantify the function of subsurface sedimentary microbial communities in situ using state-of-the-art gene expression methods (molecular proxies).« less

Microbially Induced Calcite Precipitation (MICP) - A Technology for Managing Flow and Transport in Porous and Fractured Media

NASA Astrophysics Data System (ADS)

Phillips, A. J.; Hiebert, R.; Kirksey, J.; Lauchnor, E. G.; Rothman, A.; Spangler, L.; Esposito, R.; Gerlach, R.; Cunningham, A. B.

2014-12-01

Certain microorganisms e.g., Sporosarcina pasteurii contribute enzymes that catalyze reactions which in the presence of calcium, can create saturation conditions favorable for calcium carbonate precipitation (microbially-induced calcium carbonate precipitation (MICP)). MICP can be used for a number of engineering applications including securing geologic storage of CO2 or other fluids by sealing fractures, improving wellbore integrity, and stabilizing fractured and unstable porous media. MICP treatment has the advantage of the use of small microorganisms, ~2μm, suggesting applicability to treatment of small aperture fractures not accessible to traditional treatments, for example the use of fine cement. The promotion of MICP in the subsurface is a complex reactive transport problem coupling microbial, abiotic (geochemical), geomechanical and hydrodynamic processes. In the laboratory, MICP has been demonstrated to cement together heavily fractured shale and reduce the permeability of fractures in shale and sandstone cores up to five orders of magnitude under both ambient and subsurface relevant pressure conditions (Figure 1). Most recently, a MICP fracture treatment field study was performed at a well at the Southern Company Gorgas Steam Generation Plant (Alabama) (Figure 1). The Fayetteville Sandstone at approximately 1120' below ground surface was hydraulically fractured prior to MICP treatment. After 4 days of injection of 24 calcium pulses and 6 microbial inoculations, injectivity of brine into the formation was significantly reduced. The experiment also resulted in a reduction in pressure decay which is a measure of improved wellbore integrity. These promising results suggest the potential for MICP treatment to seal fractured pathways at the field scale to improve the long-term security of geologically-stored carbon dioxide or prevent leakage of shale gas or hydraulic fracturing fluids into functional overlying aquifers, reducing environmental impacts.

Identification of Karstic Features in Lateritic Soil by an Integrated Geophysical Approach

NASA Astrophysics Data System (ADS)

Anbazhagan, P.; Rohit, Divyesh; Prabhakaran, Athul; Vidyaranya, B.

2018-06-01

Lateritic soils are widely spread across the southern and central parts of India. Lateritic formations usually have soft sediments, entrapped between hard to medium soft lateritic rock, which are leached due to the ingress of water during rainy seasons creating hollow sections or cavities which span over large lengths. Laterites are highly heterogeneous and prone to cavitation due to its weathering process; a sound knowledge of the subsurface condition is required before starting any construction. This study presents the application of integrated geophysical investigation for the identification of cavities at a mega construction site in Kerala State, India. Geophysical survey methods, namely ground penetrating radar (GPR) and multichannel analysis of surface waves (MASWs) techniques, are used to identify the heterogeneities in lateritic soils and localized cavities. The survey areas identified are critical sections of a mega construction project subjected to heavy dynamic and static loads. The preliminary GPR survey is carried out across the study areas at specific interval spacing to identify probable heterogeneities. Confirmative survey or detailed GPR and MASW surveys are carried out at the locations identified in the preliminary survey at close intervals to confirm the presence of an anomaly and identify its location. The anomalies in the GPR radargram are identified by visual inspection and trace amplitude approach. Using MASW survey, a 2D shear wave velocity profile is generated to identify low shear wave velocity zones which confirm the presence of an anomaly. On comparing the data from both GPR and MASW survey techniques, the underground cavities were successfully identified at multiple locations with further crosschecking with borings. The study further provided details on subsurface lithology at survey locations.

Virtual hydrology observatory: an immersive visualization of hydrology modeling

NASA Astrophysics Data System (ADS)

Su, Simon; Cruz-Neira, Carolina; Habib, Emad; Gerndt, Andreas

2009-02-01

The Virtual Hydrology Observatory will provide students with the ability to observe the integrated hydrology simulation with an instructional interface by using a desktop based or immersive virtual reality setup. It is the goal of the virtual hydrology observatory application to facilitate the introduction of field experience and observational skills into hydrology courses through innovative virtual techniques that mimic activities during actual field visits. The simulation part of the application is developed from the integrated atmospheric forecast model: Weather Research and Forecasting (WRF), and the hydrology model: Gridded Surface/Subsurface Hydrologic Analysis (GSSHA). Both the output from WRF and GSSHA models are then used to generate the final visualization components of the Virtual Hydrology Observatory. The various visualization data processing techniques provided by VTK are 2D Delaunay triangulation and data optimization. Once all the visualization components are generated, they are integrated into the simulation data using VRFlowVis and VR Juggler software toolkit. VR Juggler is used primarily to provide the Virtual Hydrology Observatory application with fully immersive and real time 3D interaction experience; while VRFlowVis provides the integration framework for the hydrologic simulation data, graphical objects and user interaction. A six-sided CAVETM like system is used to run the Virtual Hydrology Observatory to provide the students with a fully immersive experience.

Understanding the Impacts of Climate Change and Land Use Dynamics Using a Fully Coupled Hydrologic Feedback Model between Surface and Subsurface Systems

NASA Astrophysics Data System (ADS)

Park, C.; Lee, J.; Koo, M.

2011-12-01

Climate is the most critical driving force of the hydrologic system of the Earth. Since the industrial revolution, the impacts of anthropogenic activities to the Earth environment have been expanded and accelerated. Especially, the global emission of carbon dioxide into the atmosphere is known to have significantly increased temperature and affected the hydrologic system. Many hydrologists have contributed to the studies regarding the climate change on the hydrologic system since the Intergovernmental Panel on Climate Change (IPCC) was created in 1988. Among many components in the hydrologic system groundwater and its response to the climate change and anthropogenic activities are not fully understood due to the complexity of subsurface conditions between the surface and the groundwater table. A new spatio-temporal hydrologic model has been developed to estimate the impacts of climate change and land use dynamics on the groundwater. The model consists of two sub-models: a surface model and a subsurface model. The surface model involves three surface processes: interception, runoff, and evapotranspiration, and the subsurface model does also three subsurface processes: soil moisture balance, recharge, and groundwater flow. The surface model requires various input data including land use, soil types, vegetation types, topographical elevations, and meteorological data. The surface model simulates daily hydrological processes for rainfall interception, surface runoff varied by land use change and crop growth, and evapotranspiration controlled by soil moisture balance. The daily soil moisture balance is a key element to link two sub-models as it calculates infiltration and groundwater recharge by considering a time delay routing through a vadose zone down to the groundwater table. MODFLOW is adopted to simulate groundwater flow and interaction with surface water components as well. The model is technically flexible to add new model or modify existing model as it is developed with an object-oriented language - Python. The model also can easily be localized by simple modification of soil and crop properties. The actual application of the model after calibration was successful and results showed reliable water balance and interaction between the surface and subsurface hydrologic systems.

Integration of airborne optical and thermal imagery for archaeological subsurface structures detection: the Arpi case study (Italy)

NASA Astrophysics Data System (ADS)

Bassani, C.; Cavalli, R. M.; Fasulli, L.; Palombo, A.; Pascucci, S.; Santini, F.; Pignatti, S.

2009-04-01

The application of Remote Sensing data for detecting subsurface structures is becoming a remarkable tool for the archaeological observations to be combined with the near surface geophysics [1, 2]. As matter of fact, different satellite and airborne sensors have been used for archaeological applications, such as the identification of spectral anomalies (i.e. marks) related to the buried remnants within archaeological sites, and the management and protection of archaeological sites [3, 5]. The dominant factors that affect the spectral detectability of marks related to manmade archaeological structures are: (1) the spectral contrast between the target and background materials, (2) the proportion of the target on the surface (relative to the background), (3) the imaging system characteristics being used (i.e. bands, instrument noise and pixel size), and (4) the conditions under which the surface is being imaged (i.e. illumination and atmospheric conditions) [4]. In this context, just few airborne hyperspectral sensors were applied for cultural heritage studies, among them the AVIRIS (Airborne Visible/Infrared Imaging Spectrometer), the CASI (Compact Airborne Spectrographic Imager), the HyMAP (Hyperspectral MAPping) and the MIVIS (Multispectral Infrared and Visible Imaging Spectrometer). Therefore, the application of high spatial/spectral resolution imagery arise the question on which is the trade off between high spectral and spatial resolution imagery for archaeological applications and which spectral region is optimal for the detection of subsurface structures. This paper points out the most suitable spectral information useful to evaluate the image capability in terms of spectral anomaly detection of subsurface archaeological structures in different land cover contexts. In this study, we assess the capability of MIVIS and CASI reflectances and of ATM and MIVIS emissivities (Table 1) for subsurface archaeological prospection in different sites of the Arpi archaeological area (southern Italy). We identify, for the selected sites, three main land cover overlying the buried structures: (a) photosynthetic (i.e. green low vegetation), (b) non-photosynthetic vegetation (i.e. yellow, dry low vegetation), and (c) dry bare soil. Afterwards, we analyse the spectral regions showing an inherent potential for the archaeological detection as a function of the land cover characteristics. The classified land cover units have been used in a spectral mixture analysis to assess the land cover fractional abundance surfacing the buried structures (i.e. mark-background system). The classification and unmixing results for the CASI, MIVIS and ATM remote sensing data processing showed a good accordance both in the land cover units and in the subsurface structures identification. The integrated analysis of the unmixing results for the three sensors allowed us to establish that for the land cover characterized by green and dry vegetation (occurrence higher than 75%), the visible and near infrared (VNIR) spectral regions better enhance the buried man-made structures. In particular, if the structures are covered by more than 75% of vegetation the two most promising wavelengths for their detection are the chlorophyll peak at 0.56 m (Visible region) and the red edge region (0.67 to 0.72 m; NIR region). This result confirms that the variation induced by the subsurface structures (e.g., stone walls, tile concentrations, pavements near the surface, road networks) to the natural vegetation growth and/or colour (i.e., for different stress factors) is primarily detectable by the chlorophyll peak and the red edge region applied for the vegetation stress detection. Whereas, if dry soils cover the structures (occurrence higher than 75%), both the VNIR and thermal infrared (TIR) regions are suitable to detect the subsurface structures. This work demonstrates that airborne reflectances and emissivities data, even though at different spatial/spectral resolutions and acquisition time represent an effective and rapid tool to detect subsurface structures within different land cover contexts. As concluding results, this study reveals that the airborne multi/hyperspectral image processing can be an effective and cost-efficient tool to perform a preliminary analysis of those areas where large cultural heritage assets prioritising and localizing the sites where to apply near surface geophysics surveys. Spectral Region Spectral Resolution ( m )Spectral Range ( m) Spatial Resolution (m)IFOV (deg) ATM VIS-NIR SWIR-TIR (tot 12 ch) variable from 24 to 3100 0.42 - 1150 2 0.143 CASI VNIR (48 ch.) 0.01 0.40-0.94 2 0.115 MIVIS VNIR (28ch.) 0.02 (VIS) 0.05 (NIR) 0.43-0.83 (VIS) 1.15-1.55 (NIR) 6 - 7 0.115 SWIR (64ch.) 0.09 1.983-2.478 TIR (10ch.) 0.34-0.54 8.180-12.700 Table 1. Characteristics of airborne sensors used for the Arpi test area. 1 References 2 [1] Beck, A., Philip, G., Abdulkarim, M. and Donoghue, D., 2007. Evaluation of Corona and Ikonos high resolution satellite imagery for archaeological prospection in western Syria. Antiquity, 81: 161-175. 3 [2] Altaweel, M., 2005. The Use of ASTER Satellite Imagery in Archaeological Contexts. Archaeological Prospection, 12: 151- 166. 4 [3] Cavalli, R.M.; Colosi, F.; Palombo, A.; Pignatti, S.; Poscolieri, M. Remote hyperspectral imagery as a support to archaeological prospection. J. of Cultural Heritage 2007, 8, 272-283. 5 [4] Kucukkaya, A.G. Photogrammetry and remote sensing in archaeology. J. Quant. Spectrosc. Radiat. Transfer 2004, 97(1-3), 83-97. [5] Rowlands, A.; Sarris, A. Detection of exposed and subsurface archaeological remains using multi-sensor remote sensing. J. of Archaeological Science 2007, 34, 795-803.

Debates—Stochastic subsurface hydrology from theory to practice: The relevance of stochastic subsurface hydrology to practical problems of contaminant transport and remediation. What is characterization and stochastic theory good for?

NASA Astrophysics Data System (ADS)

Fiori, A.; Cvetkovic, V.; Dagan, G.; Attinger, S.; Bellin, A.; Dietrich, P.; Zech, A.; Teutsch, G.

2016-12-01

The emergence of stochastic subsurface hydrology stemmed from the realization that the random spatial variability of aquifer properties has a profound impact on solute transport. The last four decades witnessed a tremendous expansion of the discipline, many fundamental processes and principal mechanisms being identified. However, the research findings have not impacted significantly the application in practice, for several reasons which are discussed. The paper discusses the current status of stochastic subsurface hydrology, the relevance of the scientific results for applications and it also provides a perspective to a few possible future directions. In particular, we discuss how the transfer of knowledge can be facilitated by identifying clear goals for characterization and modeling application, relying on recent recent advances in research in these areas.

On the effects of subsurface parameters on evaporite dissolution (Switzerland)

NASA Astrophysics Data System (ADS)

Zidane, Ali; Zechner, Eric; Huggenberger, Peter; Younes, Anis

2014-05-01

Uncontrolled subsurface evaporite dissolution could lead to hazards such as land subsidence. Observed subsidences in a study area of Northwestern Switzerland were mainly due to subsurface dissolution (subrosion) of evaporites such as halite and gypsum. A set of 2D density driven flow simulations were evaluated along 1000 m long and 150 m deep 2D cross sections within the study area that is characterized by tectonic horst and graben structures. The simulations were conducted to study the effect of the different subsurface parameters that could affect the dissolution process. The heterogeneity of normal faults and its impact on the dissolution of evaporites is studied by considering several permeable faults that include non-permeable areas. The mixed finite element method (MFE) is used to solve the flow equation, coupled with the multipoint flux approximation (MPFA) and the discontinuous Galerkin method (DG) to solve the diffusion and the advection parts of the transport equation.

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.

Optical method and apparatus for detection of surface and near-subsurface defects in dense ceramics

DOEpatents

Ellingson, William A.; Brada, Mark P.

1995-01-01

A laser is used in a non-destructive manner to detect surface and near-subsurface defects in dense ceramics and particularly in ceramic bodies with complex shapes such as ceramic bearings, turbine blades, races, and the like. The laser's wavelength is selected based upon the composition of the ceramic sample and the laser can be directed on the sample while the sample is static or in dynamic rotate or translate motion. Light is scattered off surface and subsurface defects using a preselected polarization. The change in polarization angle is used to select the depth and characteristics of surface/subsurface defects. The scattered light is detected by an optical train consisting of a charge coupled device (CCD), or vidicon, television camera which, in turn, is coupled to a video monitor and a computer for digitizing the image. An analyzing polarizer in the optical train allows scattered light at a given polarization angle to be observed for enhancing sensitivity to either surface or near-subsurface defects. Application of digital image processing allows subtraction of digitized images in near real-time providing enhanced sensitivity to subsurface defects. Storing known "feature masks" of identified defects in the computer and comparing the detected scatter pattern (Fourier images) with the stored feature masks allows for automatic classification of detected defects.

Assessing Hydrologic Impacts of Land Configuration Changes Using an Integrated Hydrologic Model at the Rocky Flats Environmental Technology Site, Colorado

NASA Astrophysics Data System (ADS)

Prucha, R. H.; Dayton, C. S.; Hawley, C. M.

2002-12-01

The Rocky Flats Environmental Technology Site (RFETS) in Golden, Colorado, a former Department of Energy nuclear weapons manufacturing facility, is currently undergoing closure. The natural semi-arid interaction between surface and subsurface flow at RFETS is complex and complicated by the industrial modifications to the flow system. Using a substantial site data set, a distributed parameter, fully-integrated hydrologic model was developed to assess the hydrologic impact of different hypothetical site closure configurations on the current flow system and to better understand the integrated hydrologic behavior of the system. An integrated model with this level of detail has not been previously developed in a semi-arid area, and a unique, but comprehensive, approach was required to calibrate and validate the model. Several hypothetical scenarios were developed to simulate hydrologic effects of modifying different aspects of the site. For example, some of the simulated modifications included regrading the current land surface, changing the existing surface channel network, removing subsurface trenches and gravity drain flow systems, installing a slurry wall and geotechnical cover, changing the current vegetative cover, and converting existing buildings and pavement to permeable soil areas. The integrated flow model was developed using a rigorous physically-based code so that realistic design parameters can simulate these changes. This code also permitted evaluation of changes to complex integrated hydrologic system responses that included channelized and overland flow, pond levels, unsaturated zone storage, groundwater heads and flow directions, and integrated water balances for key areas. Results generally show that channel flow offsite decreases substantially for different scenarios, while groundwater heads generally increase within the reconfigured industrial area most of which is then discharged as evapotranspiration. These changes have significant implications to site closure and operation.

Quantifying Arctic Terrestrial Environment Behaviors Using Geophysical, Point-Scale and Remote Sensing Data

NASA Astrophysics Data System (ADS)

Dafflon, B.; Hubbard, S. S.; Ulrich, C.; Peterson, J. E.; Wu, Y.; Wainwright, H. M.; Gangodagamage, C.; Kholodov, A. L.; Kneafsey, T. J.

2013-12-01

Improvement in parameterizing Arctic process-rich terrestrial models to simulate feedbacks to a changing climate requires advances in estimating the spatiotemporal variations in active layer and permafrost properties - in sufficiently high resolution yet over modeling-relevant scales. As part of the DOE Next-Generation Ecosystem Experiments (NGEE-Arctic), we are developing advanced strategies for imaging the subsurface and for investigating land and subsurface co-variability and dynamics. Our studies include acquisition and integration of various measurements, including point-based, surface-based geophysical, and remote sensing datasets These data have been collected during a series of campaigns at the NGEE Barrow, AK site along transects that traverse a range of hydrological and geomorphological conditions, including low- to high- centered polygons and drained thaw lake basins. In this study, we describe the use of galvanic-coupled electrical resistance tomography (ERT), capacitively-coupled resistivity (CCR) , permafrost cores, above-ground orthophotography, and digital elevation model (DEM) to (1) explore complementary nature and trade-offs between characterization resolution, spatial extent and accuracy of different datasets; (2) develop inversion approaches to quantify permafrost characteristics (such as ice content, ice wedge frequency, and presence of unfrozen deep layer) and (3) identify correspondences between permafrost and land surface properties (such as water inundation, topography, and vegetation). In terms of methods, we developed a 1D-based direct search approach to estimate electrical conductivity distribution while allowing exploration of multiple solutions and prior information in a flexible way. Application of the method to the Barrow datasets reveals the relative information content of each dataset for characterizing permafrost properties, which shows features variability from below one meter length scales to large trends over more than a kilometer. Further, we used Pole- and Kite-based low-altitude aerial photography with inferred DEM, as well as DEM from LiDAR dataset, to quantify land-surface properties and their co-variability with the subsurface properties. Comparison of the above- and below-ground characterization information indicate that while some permafrost characteristics correspond with changes in hydrogeomorphological expressions, others features show more complex linkages with landscape properties. Overall, our results indicate that remote sensing data, point-scale measurements and surface geophysical measurements enable the identification of regional zones having similar relations between subsurface and land surface properties. Identification of such zonation and associated permafrost-land surface properties can be used to guide investigations of carbon cycling processes and for model parameterization.

Automated permanent resistivity monitoring of charge and discharge processes of subsurface aquifer at the Membach station, Belgium

NASA Astrophysics Data System (ADS)

Deceuster, J.; Kaufmann, O.; van Camp, M. J.; Lecocq, T.

2010-12-01

Permanent monitoring of changes in soil properties is of increasing interest in many engineering applications such as management of groundwater contamination, landslide and sinkhole risks prevention, detection of saline water intrusion, comprehension of charge and discharge processes of subsurface aquifer. As geophysical investigations allow detecting contrasts in physical properties of the subsurface, field and lab experiments have been conducted for a few years to assess the reliability of these methods to monitor temporal changes in soil properties. Among the methods available, DC resistivity tomography is recognized as one of the most promising techniques. In order to assess the efficiency of electrical resistivity in monitoring charge and discharge processes of subsurface aquifer, and also to better model hydrological effects on the gravity measurements, an on-going field experiment is conducted at the Membach station located in the eastern part of Belgium. This geophysical station is equipped with an accelerometer, seismometers and a superconducting gravimeter, installed at the end of a 130 m long tunnel excavated in a low-porosity argillaceous sandstone mount at 48.5 m depth. Continuous gravimetric observations have been taken since August 1995. Since 2004 rainfall and soil moisture changes are measured in situ. In July 2010, an automated permanent geoelectrical acquisition system was installed to monitor subsurface resistivity variations during a test period of about 6 months. The aim of this experiment is to better understand charge and discharge processes of the subsurface aquifer, which are expected to be mainly due to rainfall variations. This aquifer is localized at the top of the weathered bedrock at a depth of 4 to 5 meters. The acquisition system consists in a straight profile of 48 buried electrodes (with a 2 meters spacing) connected to a Syscal R1 resistivimeter which is automatically controlled by a computer. Resistivity measurements are taken at least twice a day at fixed hours using a combination of dipole-dipole and Wenner-Schlumberger arrays. Acquired data are filtered in order to reject faulty measures. Time-lapse inversion (Loke (1999)) is then carried out to reconstruct a 2D model of resistivity changes. Preliminary results obtained during July show changes in inverted resistivities of about 30% in the first 4 to 5 meters layer. These observations are consistent with changes in measured gravimetric water content. This seems to indicate that subsurface aquifer charge and discharge processes are mainly due to rainfall, as expected. However, inversion errors remain high even after data filtering. This could be a consequence of weather occurring in July, leading to a poor contact between the electrodes and dry host soils near the surface. This problem should not happen anymore as the rest of the monitoring experiment is conducted during the wet season. Acknowledgments This work is conducted under the auspices of the Walloon Region Ministry under the First Spin-Off program (visa n° 916974).

Cyclic voltammetry study of PEO processing of porous Ti and resulting coatings

NASA Astrophysics Data System (ADS)

Shbeh, Mohammed; Yerokhin, Aleksey; Goodall, Russell

2018-05-01

Ti is one of the most commonly used materials for biomedical applications. However, there are two issues associated with the use of it, namely its bio-inertness and high elastic modulus compared to the elastic modulus of the natural bone. Both of these hurdles could potentially be overcome by introducing a number of pores in the structure of the Ti implant to match the properties of the bone as well as improve the mechanical integration between the bone and implant, and subsequently coating it with a biologically active ceramic coating to promote chemical integration. Hence, in this study we investigated the usage of cyclic voltammetry in PEO treatment of porous Ti parts with different amount of porosity produced by both Metal Injection Moulding (MIM) and MIM in combination with a space holder. It was found that porous samples with higher porosity and open pores develop much thicker surface layers that penetrate through the inner structure of the samples forming a network of surface and subsurface coatings. The results are of potential benefit in producing surface engineered porous samples for biomedical applications which do not only address the stress shielding problem, but also improve the chemical integration.

Hydrology of prairie wetlands: Understanding the integrated surface-water and groundwater processes

USGS Publications Warehouse

Hayashi, Masaki; van der Kamp, Garth; Rosenberry, Donald O.

2016-01-01

Wetland managers and policy makers need to make decisions based on a sound scientific understanding of hydrological and ecological functions of wetlands. This article presents an overview of the hydrology of prairie wetlands intended for managers, policy makers, and researchers new to this field (e.g., graduate students), and a quantitative conceptual framework for understanding the hydrological functions of prairie wetlands and their responses to changes in climate and land use. The existence of prairie wetlands in the semi-arid environment of the Prairie-Pothole Region (PPR) depends on the lateral inputs of runoff water from their catchments because mean annual potential evaporation exceeds precipitation in the PPR. Therefore, it is critically important to consider wetlands and catchments as highly integrated hydrological units. The water balance of individual wetlands is strongly influenced by runoff from the catchment and the exchange of groundwater between the central pond and its moist margin. Land-use practices in the catchment have a sensitive effect on runoff and hence the water balance. Surface and subsurface storage and connectivity among individual wetlands controls the diversity of pond permanence within a wetland complex, resulting in a variety of eco-hydrological functionalities necessary for maintaining the integrity of prairie-wetland ecosystems.

Nitrate sinks in perennial vegetation filter strips in the toeslopes of agricultural watersheds

USDA-ARS?s Scientific Manuscript database

Integration of perennial filter strips (PFS) into the toeslope of agricultural watersheds may decrease downstream NO3 losses, especially if subsurface flow interacts with the rooting zone of the perennial vegetation. However, the long-term effectiveness of NO3 removal depends on the relative importa...

Data analysis protocol for using resistivity array as an early-warning wastewater pond leak detector

USDA-ARS?s Scientific Manuscript database

Typically, holding ponds are used to control runoff from concentrated animal feeding operations. The integrity of these holding ponds has come under increased scrutiny since subsurface leakage has the potential to affect soil and groundwater quality. Traditionally, ponds are monitored by installin...

Mountable eddy current sensor for in-situ remote detection of surface and sub-surface fatigue cracks

DOEpatents

Yepez, III, Esteban; Roach, Dennis P [Albuquerque, NM; Rackow, Kirk A [Albuquerque, NM; DeLong, Waylon A [Albuquerque, NM

2011-09-06

A wireless, integrated, mountable, portable, battery-operated, non-contact eddy current sensor that provides similar accuracy to 1970's laboratory scale equipment (e.g., a Hewlett-Packard GP4194A Impedance Analyzer) at a fraction of the size and cost.

A Tower-based Prototype VHF/UHF Radar for Subsurface Sensing: System Description and Data Inversion Results

NASA Technical Reports Server (NTRS)

Moghaddam, Mahta; Pierce, Leland; Tabatabaeenejad, Alireza; Rodriguez, Ernesto

2005-01-01

Knowledge of subsurface characteristics such as permittivity variations and layering structure could provide a breakthrough in many terrestrial and planetary science disciplines. For Earth science, knowledge of subsurface and subcanopy soil moisture layers can enable the estimation of vertical flow in the soil column linking surface hydrologic processes with that in the subsurface. For planetary science, determining the existence of subsurface water and ice is regarded as one of the most critical information needs for the study of the origins of the solar system. The subsurface in general can be described as several near-parallel layers with rough interfaces. Each homogenous rough layer can be defined by its average thickness, permittivity, and rms interface roughness assuming a known surface spectral distribution. As the number and depth of layers increase, the number of measurements needed to invert for the layer unknowns also increases, and deeper penetration capability would be required. To nondestructively calculate the characteristics of the rough layers, a multifrequency polarimetric radar backscattering approach can be used. One such system is that we have developed for data prototyping of the Microwave Observatory of Subcanopy and Subsurface (MOSS) mission concept. A tower-mounted radar makes backscattering measurements at VHF, UHF, and L-band frequencies. The radar is a pulsed CW system, which uses the same wideband antenna to transmit and receive the signals at all three frequencies. To focus the beam at various incidence angles within the beamwidth of the antenna, the tower is moved vertically and measurements made at each position. The signals are coherently summed to achieve focusing and image formation in the subsurface. This requires an estimate of wave velocity profiles. To solve the inverse scattering problem for subsurface velocity profile simultaneously with radar focusing, we use an iterative technique based on a forward numerical solution of the layered rough surface problem. The layers are each defined in terms of a small number of unknown distributions as given above. An a priori estimate of the solution is first assumed, based on which the forward problem is solved for the backscattered measurements. This is compared with the measured data and using iterative techniques an update to the solution for the unknowns is calculated. The process continues until convergence is achieved. Numerical results will be shown using actual radar data acquired with the MOSS tower radar system in Arizona in Fall 2003, and compared with in-situ measurements.

Transport of Chemical Vapors from Subsurface Sources to Atmosphere as Affected by Shallow Subsurface and Atmospheric Conditions

NASA Astrophysics Data System (ADS)

Rice, A. K.; Smits, K. M.; Hosken, K.; Schulte, P.; Illangasekare, T. H.

2012-12-01

Understanding the movement and modeling of chemical vapor through unsaturated soil in the shallow subsurface when subjected to natural atmospheric thermal and mass flux boundary conditions at the land surface is of importance to applications such as landmine detection and vapor intrusion into subsurface structures. New, advanced technologies exist to sense chemical signatures at the land/atmosphere interface, but interpretation of these sensor signals to make assessment of source conditions remains a challenge. Chemical signatures are subject to numerous interactions while migrating through the unsaturated soil environment, attenuating signal strength and masking contaminant source conditions. The dominant process governing movement of gases through porous media is often assumed to be Fickian diffusion through the air phase with minimal or no quantification of other processes contributing to vapor migration, such as thermal diffusion, convective gas flow due to the displacement of air, expansion/contraction of air due to temperature changes, temporal and spatial variations of soil moisture and fluctuations in atmospheric pressure. Soil water evaporation and interfacial mass transfer add to the complexity of the system. The goal of this work is to perform controlled experiments under transient conditions of soil moisture, temperature and wind at the land/atmosphere interface and use the resulting dataset to test existing theories on subsurface gas flow and iterate between numerical modeling efforts and experimental data. Ultimately, we aim to update conceptual models of shallow subsurface vapor transport to include conditionally significant transport processes and inform placement of mobile sensors and/or networks. We have developed a two-dimensional tank apparatus equipped with a network of sensors and a flow-through head space for simulation of the atmospheric interface. A detailed matrix of realistic atmospheric boundary conditions was applied in a series of experiments. Water saturation, capillary pressure, air and soil temperature, and relative humidity were continuously monitored. Aqueous TCE was injected into the tank below the water table and allowed to volatilize. TCE concentration exiting the tank head space was measured through interval sampling by direct injection into a gas chromatograph. To quantify the transient concentration of TCE vapor in the soil pore space a novel use of Solid Phase Micro-Extraction (SPME) was developed. Results from our numerical simulations were compared with the experimental data, which demonstrated the importance of considering the interaction of the atmosphere with the subsurface in conceptualization and numerical model development. Results also emphasize that soil saturation and transient sorption have a significant effect on vapor transport through the vadose zone. Follow-up tests and detailed analyses are still underway. Additional applications of this work include carbon sequestration leakage, methane contamination in the shallow subsurface and environmental impact of hydraulic fracturing.

Impact of CO 2 on the Evolution of Microbial Communities Exposed to Carbon Storage Conditions, Enhanced Oil Recovery, and CO 2 Leakage

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

Gulliver, Djuna; Gregory, Kelvin B.; Lowry, Gregorgy V.

Geologic carbon storage (GCS) is a crucial part of a proposed mitigation strategy to reduce the anthropogenic carbon dioxide (CO 2) emissions to the atmosphere. During this process, CO 2 is injected as super critical carbon dioxide (SC-CO 2) in confined deep subsurface storage units, such as saline aquifers and depleted oil reservoirs. The deposition of vast amounts of CO 2 in subsurface geologic formations could unintentionally lead to CO 2 leakage into overlying freshwater aquifers. Introduction of CO 2 into these subsurface environments will greatly increase the CO 22 concentration and will create CO 2 concentration gradients that drivemore » changes in the microbial communities present. While it is expected that altered microbial communities will impact the biogeochemistry of the subsurface, there is no information available on how CO 2 gradients will impact these communities. The overarching goal of this project is to understand how CO 2 exposure will impact subsurface microbial communities at temperatures and pressures that are relevant to GCS and CO 2 leakage scenarios. To meet this goal, unfiltered, aqueous samples from a deep saline aquifer, a depleted oil reservoir, and a fresh water aquifer were exposed to varied concentrations of CO 2 at reservoir pressure and temperature. The microbial ecology of the samples was examined using molecular, DNA-based techniques. The results from these studies were also compared across the sites to determine any existing trends. Results reveal that increasing CO 2 leads to decreased DNA concentrations regardless of the site, suggesting that microbial processes will be significantly hindered or absent nearest the CO 2 injection/leakage plume where CO 2 concentrations are highest. At CO 2 exposures expected downgradient from the CO 2 plume, selected microorganisms emerged as dominant in the CO 2 exposed conditions. Results suggest that the altered microbial community was site specific and highly dependent on pH. The site-dependent results suggest a limited ability to predict the emerging dominant species for other CO 2 exposed environments. This study improves the understanding of how a subsurface microbial community may respond to conditions expected from GCS and CO 2 leakage. This is the first step for understanding how a CO 2-altered microbial community may impact injectivity, permanence of stored CO 2, and subsurface water quality. Future work with microbial communities from new subsurface sites would increase the current understanding of this project. Additionally, incorporation of metagenomic methods would increase understanding of potential microbial processes that may be prevalent in CO 2 exposed environments.« less

Impact of CO 2 on the Evolution of Microbial Communities Exposed to Carbon Storage Conditions, Enhanced Oil Recovery, and CO 2 Leakage

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

Gulliver, Djuna M.; Gregory, Kelvin B.; Lowry, Gregory V.

Geologic carbon storage (GCS) is a crucial part of a proposed mitigation strategy to reduce the anthropogenic carbon dioxide (CO 2) emissions to the atmosphere. During this process, CO 2 is injected as super critical carbon dioxide (SC-CO 2) in confined deep subsurface storage units, such as saline aquifers and depleted oil reservoirs. The deposition of vast amounts of CO 2 in subsurface geologic formations could unintentionally lead to CO 2 leakage into overlying freshwater aquifers. Introduction of CO 2 into these subsurface environments will greatly increase the CO 2 concentration and will create CO 2 concentration gradients that drivemore » changes in the microbial communities present. While it is expected that altered microbial communities will impact the biogeochemistry of the subsurface, there is no information available on how CO 2 gradients will impact these communities. The overarching goal of this project is to understand how CO 2 exposure will impact subsurface microbial communities at temperatures and pressures that are relevant to GCS and CO 2 leakage scenarios. To meet this goal, unfiltered, aqueous samples from a deep saline aquifer, a depleted oil reservoir, and a fresh water aquifer were exposed to varied concentrations of CO 2 at reservoir pressure and temperature. The microbial ecology of the samples was examined using molecular, DNA-based techniques. The results from these studies were also compared across the sites to determine any existing trends. Results reveal that increasing CO 2 leads to decreased DNA concentrations regardless of the site, suggesting that microbial processes will be significantly hindered or absent nearest the CO 2 injection/leakage plume where CO 2 concentrations are highest. At CO 2 exposures expected downgradient from the CO 2 plume, selected microorganisms emerged as dominant in the CO 2 exposed conditions. Results suggest that the altered microbial community was site specific and highly dependent on pH. The site-dependent results suggest a limited ability to predict the emerging dominant species for other CO 2-exposed environments. This study improves the understanding of how a subsurface microbial community may respond to conditions expected from GCS and CO 2 leakage. This is the first step for understanding how a CO 2-altered microbial community may impact injectivity, permanence of stored CO 2, and subsurface water quality. Future work with microbial communities from new subsurface sites would increase the current understanding of this project. Additionally, incorporation of metagenomic methods would increase understanding of potential microbial processes that may be prevalent in CO 2 exposed environments.« less

Chip formation and surface integrity in high-speed machining of hardened steel

NASA Astrophysics Data System (ADS)

Kishawy, Hossam Eldeen A.

Increasing demands for high production rates as well as cost reduction have emphasized the potential for the industrial application of hard turning technology during the past few years. Machining instead of grinding hardened steel components reduces the machining sequence, the machining time, and the specific cutting energy. Hard turning Is characterized by the generation of high temperatures, the formation of saw toothed chips, and the high ratio of thrust to tangential cutting force components. Although a large volume of literature exists on hard turning, the change in machined surface physical properties represents a major challenge. Thus, a better understanding of the cutting mechanism in hard turning is still required. In particular, the chip formation process and the surface integrity of the machined surface are important issues which require further research. In this thesis, a mechanistic model for saw toothed chip formation is presented. This model is based on the concept of crack initiation on the free surface of the workpiece. The model presented explains the mechanism of chip formation. In addition, experimental investigation is conducted in order to study the chip morphology. The effect of process parameters, including edge preparation and tool wear on the chip morphology, is studied using Scanning Electron Microscopy (SEM). The dynamics of chip formation are also investigated. The surface integrity of the machined parts is also investigated. This investigation focusses on residual stresses as well as surface and sub-surface deformation. A three dimensional thermo-elasto-plastic finite element model is developed to predict the machining residual stresses. The effect of flank wear is introduced during the analysis. Although residual stresses have complicated origins and are introduced by many factors, in this model only the thermal and mechanical factors are considered. The finite element analysis demonstrates the significant effect of the heat generated during cutting on the residual stresses. The machined specimens are also examined using x-ray diffraction technique to clarify the effect of different speeds, feeds and depths of cut as well as different edge preparations on the residual stress distribution beneath the machined surface. A reasonable agreement between the predicted and measured residual stress is obtained. The results obtained demonstrate the possibility of eliminating the existence of high tensile residual stresses in the workpiece surface by selecting the proper cutting conditions. The machined surfaces are examined using SEM to study the effect of different process parameters and edge preparations on the quality of the machined surface. The phenomenon of material side flow is investigated to clarify the mechanism of this phenomenon. The effect of process parameters and edge preparations on sub-surface deformation is also investigated.

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.

Hyporheic Passive Flux Meters Reveal Inverse Vertical Zonation and High Seasonality of Nitrogen Processing in an Anthropogenically Modified Stream (Holtemme, Germany)

NASA Astrophysics Data System (ADS)

Kunz, Julia Vanessa; Annable, Michael D.; Rao, Suresh; Rode, Michael; Borchardt, Dietrich

2017-12-01

Transformation and retention of nitrogen and other biologically reactive solutes in the hyporheic zones of running water contribute to an essential ecosystem service. However, the synoptic impact of intense agricultural or urban land-uses, elevated nutrient loading, flow alterations, riparian clear-cutting, and channelization on the source-sink behavior of solutes in hyporheic zones remains largely uncharacterized and unquantified. Therefore, we studied nutrient dynamics in a hydromorphologically and chemically modified stream reach using a new monitoring approach allowing the simultaneous measurement of nutrient and water flux through a screened area in the subsurface of rivers (hyporheic passive flux meter, HPFM). With HPFMs we directly assessed time-integrated lateral hyporheic nitrate fluxes during early spring and midsummer covering different temperature and discharge regimes. Contrary to our expectations, higher stream discharge coincided with substantially lower hyporheic exchange rates. While in streams featuring a natural morphology, bed form induced exchange commonly increases with surface flow, the influence of groundwater level was dominant in this reach. Furthermore, in contrast to less impacted environments, where progressive substrate depletion with depths reduces metabolic rates in the subsurface, we identified not the upper, but the intermediate layer of the hyporheic zone as hot spot of nutrient turnover. Overall, the hyporheic zone at the study site functioned partly as nitrate source, partly as a sink. Neither of the commonly used determinants redox state and residence time could explain this source or sink function. Our results give clear evidence to carefully transfer the knowledge of hyporheic zone processes from "natural" systems to anthropologically modified streams.

Assessing the Impact of Topography on Groundwater Salinization Due to Storm Surge Inundation

NASA Astrophysics Data System (ADS)

Yu, X.; Yang, J.; Graf, T.; Koneshloo, M.; O'Neal, M. A.; Michael, H. A.

2015-12-01

The sea-level rise and increase in the frequency and intensity of coastal storms due to climate change are likely to exacerbate adverse effects of storm surges on low-lying coastal areas. The landward flow of water during storm surges introduces salt to surficial coastal aquifers and threatens groundwater resources. Coastal topography (e.g. ponds, dunes, canals) likely has a strong impact on overwash and salinization processes, but is generally highly simplified in modeling studies. To understand the topographic impacts on groundwater salinization, we modeled overwash and variable-density groundwater flow and salt transport in 3D using the fully coupled surface and subsurface numerical simulator, HydroGeoSphere. The model simulates the coastal aquifer as an integrated system considering processes such as overland flow, coupled surface and subsurface exchange, variably saturated flow, and variable-density flow. To represent various coastal landscape types, we started with realistic coastal topography from Delaware, USA, and then generated synthetic fields with differing shore-perpendicular connectivity and surface depressions. The groundwater salinization analysis suggested that the topographic connectivity promoting overland flow controls the volume of aquifer that is salinized. In contrast, depression storage of surface water mainly controls the time for infiltrated salt to flush from the aquifer. The results indicate that for a range of synthetic conditions, topography increases the flushing time of salt by 20-300% relative to an equivalent "simple slope" in which topographic variation is absent. Our study suggests that topography have a significant impact on overwash salinization, with important implications for land management at local scales and groundwater vulnerability assessment at regional to global scales.

Evaluation of a Genome-Scale In Silico Metabolic Model for Geobacter metallireducens Using Proteomic Data from a Field Biostimulation Experiment

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

Fang, Yilin; Wilkins, Michael J.; Yabusaki, Steven B.

2012-12-12

Biomass and shotgun global proteomics data that reflected relative protein abundances from samples collected during the 2008 experiment at the U.S. Department of Energy Integrated Field-Scale Subsurface Research Challenge site in Rifle, Colorado, provided an unprecedented opportunity to validate a genome-scale metabolic model of Geobacter metallireducens and assess its performance with respect to prediction of metal reduction, biomass yield, and growth rate under dynamic field conditions. Reconstructed from annotated genomic sequence, biochemical, and physiological data, the constraint-based in silico model of G. metallireducens relates an annotated genome sequence to the physiological functions with 697 reactions controlled by 747 enzyme-coding genes.more » Proteomic analysis showed that 180 of the 637 G. metallireducens proteins detected during the 2008 experiment were associated with specific metabolic reactions in the in silico model. When the field-calibrated Fe(III) terminal electron acceptor process reaction in a reactive transport model for the field experiments was replaced with the genome-scale model, the model predicted that the largest metabolic fluxes through the in silico model reactions generally correspond to the highest abundances of proteins that catalyze those reactions. Central metabolism predicted by the model agrees well with protein abundance profiles inferred from proteomic analysis. Model discrepancies with the proteomic data, such as the relatively low fluxes through amino acid transport and metabolism, revealed pathways or flux constraints in the in silico model that could be updated to more accurately predict metabolic processes that occur in the subsurface environment.« less

Simulating hydrologic and hydraulic processes throughout the Amazon River Basin

USGS Publications Warehouse

Beighley, R.E.; Eggert, K.G.; Dunne, T.; He, Y.; Gummadi, V.; Verdin, K.L.

2009-01-01

Presented here is a model framework based on a land surface topography that can be represented with various degrees of resolution and capable of providing representative channel/floodplain hydraulic characteristics on a daily to hourly scale. The framework integrates two models: (1) a water balance model (WBM) for the vertical fluxes and stores of water in and through the canopy and soil layers based on the conservation of mass and energy, and (2) a routing model for the horizontal routing of surface and subsurface runoff and channel and floodplain waters based on kinematic and diffusion wave methodologies. The WBM is driven by satellite-derived precipitation (TRMM_3B42) and air temperature (MOD08_M3). The model's use of an irregular computational grid is intended to facilitate parallel processing for applications to continental and global scales. Results are presented for the Amazon Basin over the period Jan 2001 through Dec 2005. The model is shown to capture annual runoff totals, annual peaks, seasonal patterns, and daily fluctuations over a range of spatial scales (>1, 000 to < 4·7M km2). For the period of study, results suggest basin-wide total water storage changes in the Amazon vary by approximately + /− 5 to 10 cm, and the fractional components accounting for these changes are: root zone soil moisture (20%), subsurface water being routed laterally to channels (40%) and channel/floodplain discharge (40%). Annual variability in monthly water storage changes by + /− 2·5 cm is likely due to 0·5 to 1 month variability in the arrival of significant rainfall periods throughout the basin.

STRUCTURAL HETEROGENEITIES AND PALEO FLUID FLOW IN AN ANALOG SANDSTONE RESERVOIR 2001-2004

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

Pollard, David; Aydin, Atilla

2005-02-22

Fractures and faults are brittle structural heterogeneities that can act both as conduits and barriers with respect to fluid flow in rock. This range in the hydraulic effects of fractures and faults greatly complicates the challenges faced by geoscientists working on important problems: from groundwater aquifer and hydrocarbon reservoir management, to subsurface contaminant fate and transport, to underground nuclear waste isolation, to the subsurface sequestration of CO2 produced during fossil-fuel combustion. The research performed under DOE grant DE-FG03-94ER14462 aimed to address these challenges by laying a solid foundation, based on detailed geological mapping, laboratory experiments, and physical process modeling, onmore » which to build our interpretive and predictive capabilities regarding the structure, patterns, and fluid flow properties of fractures and faults in sandstone reservoirs. The material in this final technical report focuses on the period of the investigation from July 1, 2001 to October 31, 2004. The Aztec Sandstone at the Valley of Fire, Nevada, provides an unusually rich natural laboratory in which exposures of joints, shear deformation bands, compaction bands and faults at scales ranging from centimeters to kilometers can be studied in an analog for sandstone aquifers and reservoirs. The suite of structures there has been documented and studied in detail using a combination of low-altitude aerial photography, outcrop-scale mapping and advanced computational analysis. In addition, chemical alteration patterns indicative of multiple paleo fluid flow events have been mapped at outcrop, local and regional scales. The Valley of Fire region has experienced multiple episodes of fluid flow and this is readily evident in the vibrant patterns of chemical alteration from which the Valley of Fire derives its name. We have successfully integrated detailed field and petrographic observation and analysis, process-based mechanical modeling, and numerical simulation of fluid flow to study a typical sandstone aquifer/reservoir at a variety of scales. We have produced many tools and insights which can be applied to active subsurface flow systems and practical problems of pressing global importance.« less

The Study of Microbial Environmental Processes Related to the Natural Attenuation of Uranium at the Rifle Site using Systems-level Biology

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

Methe, Barbara; Lipton, Mary; Mahadevan, Krishna

Microbes exist in communities in the environment where they are fundamental drivers of global carbon, nutrient and metal cycles. In subsurface environments, they possess significant metabolic potential to affect these global cycles including the transformation of radionuclides. This study examined the influence of microbial communities in sediment zones undergoing biogeochemical cycling of carbon, nutrients and metals including natural attenuation of uranium. This study examined the relationship of both the microbiota (taxonomy) and their metabolic capacity (function) in driving carbon, nutrient and metal cycles including uranium reduction at the Department of Energy (DOE) Rifle Integrated Field Research Challenge (RIFRC). Objectives ofmore » this project were: 1) to apply systems-level biology through application of ‘metaomics’ approaches (collective analyses of whole microbial community DNA, RNA and protein) to the study of microbial environmental processes and their relationship to C, N and metals including the influence of microbial communities on uranium contaminant mobility in subsurface settings undergoing natural attenuation, 2) improve methodologies for data generation using metaomics (collectively metagenomics, metatranscriptomics and proteomics) technologies and analysis and interpretation of that data and 3) use the data generated from these studies towards microbial community-scale metabolic modeling. The strategy for examining these subsurface microbial communities was to generate sequence reads from microbial community DNA (metagenomics or whole genome shotgun sequencing (WGS)) and RNA (metatranscriptomcs or RNAseq) and protein information using proteomics. Results were analyzed independently and through computational modeling. Overall, the community model generated information on the microbial community structure that was observed using metaomic approaches at RIFRC sites and thus provides an important framework for continued community modeling development. The model as created is capable of predicting the response of the community structure in changing environments such as anoxic/oxic conditions or limitations by carbon or nutrients. The ability to more accurately model these responses is critical to understanding carbon and energy flows in an ecosystem is critical towards improving our ability to make predictions that can be used to design more efficient remediation and management strategies, and better understand the implications of environmental perturbations on these ecosystems.« less

CO2 Driven Mineral Transformations in Fractured Reservoir

NASA Astrophysics Data System (ADS)

Schaef, T.

2015-12-01

Engineering fracture systems in low permeable formations to increase energy production, accelerate heat extraction, or to enhance injectivity for storing anthropogenic CO2, is a challenging endeavor. To complicate matters, caprocks, essential components of subsurface reservoirs, need to maintain their sealing integrity in this modified subsurface system. Supercritical CO2 (scCO2), a proposed non-aqueous based working fluid, is capable of driving mineral transformations in fracture environments. Water dissolution in scCO2 significantly impacts the reactivity of this fluid, largely due to the development of thin adsorbed H2O films on the surfaces of exposed rocks and minerals. Adsorbed H2O films are geochemically complex microenvironments that host mineral dissolution and precipitation processes that could be tailored to influence overall formation permeability. Furthermore, manipulating the composition of injected CO2 (e.g., moisture content and/or reactive gases such as O2, NOx, or SOx) could stimulate targeted mineral transformations that enhance or sustain reservoir performance. PNNL has developed specialized experimental techniques that can be used to characterize chemical reactions occurring between minerals and pressurized gases. For example, hydration of a natural shale sample (Woodford Shale) has been characterized by an in situ infrared spectroscopic technique as water partitions from the scCO2 onto the shale. Mineral dissolution and carbonate precipitation reactions were tracked by monitoring changes of Si-O and C-O stretching bands, respectively Structural changes indicated expandable clays in the shale such as montmorillonite are intercalated with scCO2, a process not observed with the non-expandable kaolinite component. Extreme scale ab initio molecular dynamics simulations were used in conjunction with model mineral systems to identify the driving force and mechanism of water films. They showed that the film nucleation and formation on minerals is driven by both enthalpic and entropic requirements. Collectively, the synergy between laboratory observations, state-of-the-art atomistic simulations and reservoir modeling has generated important insights for the design and engineering of subsurface reservoirs for CO2 storage and energy extraction.

Utilizing High-Performance Computing to Investigate Parameter Sensitivity of an Inversion Model for Vadose Zone Flow and Transport

NASA Astrophysics Data System (ADS)

Fang, Z.; Ward, A. L.; Fang, Y.; Yabusaki, S.

2011-12-01

High-resolution geologic models have proven effective in improving the accuracy of subsurface flow and transport predictions. However, many of the parameters in subsurface flow and transport models cannot be determined directly at the scale of interest and must be estimated through inverse modeling. A major challenge, particularly in vadose zone flow and transport, is the inversion of the highly-nonlinear, high-dimensional problem as current methods are not readily scalable for large-scale, multi-process models. In this paper we describe the implementation of a fully automated approach for addressing complex parameter optimization and sensitivity issues on massively parallel multi- and many-core systems. The approach is based on the integration of PNNL's extreme scale Subsurface Transport Over Multiple Phases (eSTOMP) simulator, which uses the Global Array toolkit, with the Beowulf-Cluster inspired parallel nonlinear parameter estimation software, BeoPEST in the MPI mode. In the eSTOMP/BeoPEST implementation, a pre-processor generates all of the PEST input files based on the eSTOMP input file. Simulation results for comparison with observations are extracted automatically at each time step eliminating the need for post-process data extractions. The inversion framework was tested with three different experimental data sets: one-dimensional water flow at Hanford Grass Site; irrigation and infiltration experiment at the Andelfingen Site; and a three-dimensional injection experiment at Hanford's Sisson and Lu Site. Good agreements are achieved in all three applications between observations and simulations in both parameter estimates and water dynamics reproduction. Results show that eSTOMP/BeoPEST approach is highly scalable and can be run efficiently with hundreds or thousands of processors. BeoPEST is fault tolerant and new nodes can be dynamically added and removed. A major advantage of this approach is the ability to use high-resolution geologic models to preserve the spatial structure in the inverse model, which leads to better parameter estimates and improved predictions when using the inverse-conditioned realizations of parameter fields.

Mapping Site Remediation with Electrical Resistivity Tomography Explored via Coupled-Model Simulations

NASA Astrophysics Data System (ADS)

Power, C.; Gerhard, J. I.; Tsourlos, P.; Giannopoulos, A.

2011-12-01

Remediation programs for sites contaminated with dense non-aqueous phase liquids (DNAPLs) would benefit from an ability to non-intrusively map the evolving volume and extent of the DNAPL source zone. Electrical resistivity tomography (ERT) is a well-established geophysical tool, widely used outside the remediation industry, that has significant potential for mapping DNAPL source zones. However, that potential has not been realized due to challenges in data interpretation from contaminated sites - in either a qualitative or quantitative way. The objective of this study is to evaluate the potential of ERT to map realistic, evolving DNAPL source zones within complex subsurface environments during remedial efforts. For this purpose, a novel coupled model was developed that integrates a multiphase flow model (DNAPL3D-MT), which generates realistic DNAPL release scenarios, with 3DINV, an ERT model which calculates the corresponding resistivity response. This presentation will describe the developed model coupling methodology, which integrates published petrophysical relationships to generate an electrical resistivity field that accounts for both the spatial heterogeneity of subsurface soils and the evolving spatial distribution of fluids (including permeability, porosity, clay content and air/water/DNAPL saturation). It will also present an example in which the coupled model was employed to explore the ability of ERT to track the remediation of a DNAPL source zone. A field-scale, three-dimensional release of chlorinated solvent DNAPL into heterogeneous clayey sand was simulated, including the subsurface migration and subsequent removal of the DNAPL source zone via dissolution in groundwater. Periodic surveys of this site via ERT applied at the surface were then simulated and inversion programs were used to calculate the subsurface distribution of electrical properties. This presentation will summarize this approach and its potential as a research tool exploring the range of site conditions under which ERT may prove useful in aiding DNAPL site remediation. Moreover, it is expected to provide a cost-effective avenue to test optimum ERT data acquisition, inversion and interpretative tools at contaminated sites.

Catchment Tomography - Joint Estimation of Surface Roughness and Hydraulic Conductivity with the EnKF

NASA Astrophysics Data System (ADS)

Baatz, D.; Kurtz, W.; Hendricks Franssen, H. J.; Vereecken, H.; Kollet, S. J.

2017-12-01

Parameter estimation for physically based, distributed hydrological models becomes increasingly challenging with increasing model complexity. The number of parameters is usually large and the number of observations relatively small, which results in large uncertainties. A moving transmitter - receiver concept to estimate spatially distributed hydrological parameters is presented by catchment tomography. In this concept, precipitation, highly variable in time and space, serves as a moving transmitter. As response to precipitation, runoff and stream discharge are generated along different paths and time scales, depending on surface and subsurface flow properties. Stream water levels are thus an integrated signal of upstream parameters, measured by stream gauges which serve as the receivers. These stream water level observations are assimilated into a distributed hydrological model, which is forced with high resolution, radar based precipitation estimates. Applying a joint state-parameter update with the Ensemble Kalman Filter, the spatially distributed Manning's roughness coefficient and saturated hydraulic conductivity are estimated jointly. The sequential data assimilation continuously integrates new information into the parameter estimation problem, especially during precipitation events. Every precipitation event constrains the possible parameter space. In the approach, forward simulations are performed with ParFlow, a variable saturated subsurface and overland flow model. ParFlow is coupled to the Parallel Data Assimilation Framework for the data assimilation and the joint state-parameter update. In synthetic, 3-dimensional experiments including surface and subsurface flow, hydraulic conductivity and the Manning's coefficient are efficiently estimated with the catchment tomography approach. A joint update of the Manning's coefficient and hydraulic conductivity tends to improve the parameter estimation compared to a single parameter update, especially in cases of biased initial parameter ensembles. The computational experiments additionally show to which degree of spatial heterogeneity and to which degree of uncertainty of subsurface flow parameters the Manning's coefficient and hydraulic conductivity can be estimated efficiently.

Baseline hydraulic performance of the Heathrow constructed wetlands subsurface flow system.

PubMed

Richter, K M; Margetts, J R; Saul, A J; Guymer, I; Worrall, P

2003-01-01

A constructed wetland treatment system has been commissioned by BAA (formerly the British Airports Authority) in order to attenuate airfield runoff contaminated with de-icant and other potentially polluting materials from Heathrow Airport. Airfield runoff containing de-icants has the potential to impose significant oxygen demands on water bodies. The site consists of a number of integrated treatment systems, including a 1 ha rafted reed bed canal system and a 2 ha sub-surface flow gravel reed bed. This research project is concerned with the performance of the subsurface flow reed beds, though attention will be paid in this paper to the operation of the whole system. Prior to the planting of the subsurface flow reed beds, flow-tracing experiments were carried out on the three different types of subsurface flow beds, so that the baseline performance of the system could be quantified. In association, data regarding the soil organic matter content was also collected prior to the planting of the beds. As expected, soil organic matter content is observed to be negligible within the bed, though a small amount of build up was observed in localised areas on the surface of the beds. This was attributed to the growth of algae in depressions where standing water persisted during the construction phase. Few studies exist which provide detailed measurements into the cause and effect of variations in hydraulic conductivity within an operational reed bed system. The data presented here form the baseline results for an ongoing study into the investigation of the change in hydraulic conductivity of an operational reed bed system.

Paleokarst processes in the Eocene limestones of the Pyramids Plateau, Giza, Egypt

NASA Astrophysics Data System (ADS)

El Aref, M. M.; Refai, E.

The Eocene limestones of the Pyramids plateau are characterized by landforms of stepped terraced escarpment and karst ridges with isolated hills. The carbonate country rocks are also dominated by minor surface, surface to subsurface and subsurface solution features associated with karst products. The systematic field observations eludicate the denudation trend of the minor solution features and suggest the origin of the regional landscapes. The lithologic and structural characters of the limestone country rocks comprise the main factors controlling the surface and subsurface karst evolution. The development of the karst features and the associated sediments in the study area provides information on the paleohydrolic, chemical and climatic environments involved in the origin of the karstification.

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.

Microbial abundance in the deep subsurface of the Chesapeake Bay impact crater: Relationship to lithology and impact processes

USGS Publications Warehouse

Cockell, Charles S.; Gronstal, Aaron L.; Voytek, Mary A.; Kirshtein, Julie D.; Finster, Kai; Sanford, Ward E.; Glamoclija, Mihaela; Gohn, Gregroy S.; Powars, David S.; Horton, J. Wright

2009-01-01

Asteroid and comet impact events are known to cause profound disruption to surface ecosystems. The aseptic collection of samples throughout a 1.76-km-deep set of cores recovered from the deep subsurface of the Chesapeake Bay impact structure has allowed the study of the subsurface biosphere in a region disrupted by an impactor. Microbiological enumerations suggest the presence of three major microbiological zones. The upper zone (127–867 m) is characterized by a logarithmic decline in microbial abundance from the surface through the postimpact section of Miocene to Upper Eocene marine sediments and across the transition into the upper layers of the impact tsunami resurge sediments and sediment megablocks. In the middle zone (867–1397 m) microbial abundances are below detection. This zone is predominantly quartz sand, primarily composed of boulders and blocks, and it may have been mostly sterilized by the thermal pulse delivered during impact. No samples were collected from the large granite block (1096–1371 m). The lowest zone (below 1397 m) of increasing microbial abundance coincides with a region of heavily impact-fractured, hydraulically conductive suevite and fractured schist. These zones correspond to lithologies influenced by impact processes. Our results yield insights into the influence of impacts on the deep subsurface biosphere.

Physically based modeling in catchment hydrology at 50: Survey and outlook

NASA Astrophysics Data System (ADS)

Paniconi, Claudio; Putti, Mario

2015-09-01

Integrated, process-based numerical models in hydrology are rapidly evolving, spurred by novel theories in mathematical physics, advances in computational methods, insights from laboratory and field experiments, and the need to better understand and predict the potential impacts of population, land use, and climate change on our water resources. At the catchment scale, these simulation models are commonly based on conservation principles for surface and subsurface water flow and solute transport (e.g., the Richards, shallow water, and advection-dispersion equations), and they require robust numerical techniques for their resolution. Traditional (and still open) challenges in developing reliable and efficient models are associated with heterogeneity and variability in parameters and state variables; nonlinearities and scale effects in process dynamics; and complex or poorly known boundary conditions and initial system states. As catchment modeling enters a highly interdisciplinary era, new challenges arise from the need to maintain physical and numerical consistency in the description of multiple processes that interact over a range of scales and across different compartments of an overall system. This paper first gives an historical overview (past 50 years) of some of the key developments in physically based hydrological modeling, emphasizing how the interplay between theory, experiments, and modeling has contributed to advancing the state of the art. The second part of the paper examines some outstanding problems in integrated catchment modeling from the perspective of recent developments in mathematical and computational science.

Processes contributing to resilience of coastal wetlands to sea-level rise

USGS Publications Warehouse

Stagg, Camille L.; Krauss, Ken W.; Cahoon, Donald R.; Cormier, Nicole; Conner, William H.; Swarzenski, Christopher M.

2016-01-01

The objectives of this study were to identify processes that contribute to resilience of coastal wetlands subject to rising sea levels and to determine whether the relative contribution of these processes varies across different wetland community types. We assessed the resilience of wetlands to sea-level rise along a transitional gradient from tidal freshwater forested wetland (TFFW) to marsh by measuring processes controlling wetland elevation. We found that, over 5 years of measurement, TFFWs were resilient, although some marginally, and oligohaline marshes exhibited robust resilience to sea-level rise. We identified fundamental differences in how resilience is maintained across wetland community types, which have important implications for management activities that aim to restore or conserve resilient systems. We showed that the relative importance of surface and subsurface processes in controlling wetland surface elevation change differed between TFFWs and oligohaline marshes. The marshes had significantly higher rates of surface accretion than the TFFWs, and in the marshes, surface accretion was the primary contributor to elevation change. In contrast, elevation change in TFFWs was more heavily influenced by subsurface processes, such as root zone expansion or compaction, which played an important role in determining resilience of TFFWs to rising sea level. When root zone contributions were removed statistically from comparisons between relative sea-level rise and surface elevation change, sites that previously had elevation rate deficits showed a surplus. Therefore, assessments of wetland resilience that do not include subsurface processes will likely misjudge vulnerability to sea-level rise.

Seasonal Variability in Vadose zone biodegradation at a crude oil pipeline rupture site

USGS Publications Warehouse

Sihota, Natasha J.; Trost, Jared J.; Bekins, Barbara; Berg, Andrew M.; Delin, Geoffrey N.; Mason, Brent E.; Warren, Ean; Mayer, K. Ulrich

2016-01-01

Understanding seasonal changes in natural attenuation processes is critical for evaluating source-zone longevity and informing management decisions. The seasonal variations of natural attenuation were investigated through measurements of surficial CO2 effluxes, shallow soil CO2 radiocarbon contents, subsurface gas concentrations, soil temperature, and volumetric water contents during a 2-yr period. Surficial CO2 effluxes varied seasonally, with peak values of total soil respiration (TSR) occurring in the late spring and summer. Efflux and radiocarbon data indicated that the fractional contributions of natural soil respiration (NSR) and contaminant soil respiration (CSR) to TSR varied seasonally. The NSR dominated in the spring and summer, and CSR dominated in the fall and winter. Subsurface gas concentrations also varied seasonally, with peak values of CO2 and CH4 occurring in the fall and winter. Vadose zone temperatures and subsurface CO2 concentrations revealed a correlation between contaminant respiration and temperature. A time lag of 5 to 7 mo between peak subsurface CO2 concentrations and peak surface efflux is consistent with travel-time estimates for subsurface gas migration. Periods of frozen soils coincided with depressed surface CO2 effluxes and elevated CO2 concentrations, pointing to the temporary presence of an ice layer that inhibited gas transport. Quantitative reactive transport simulations demonstrated aspects of the conceptual model developed from field measurements. Overall, results indicated that source-zone natural attenuation (SZNA) rates and gas transport processes varied seasonally and that the average annual SZNA rate estimated from periodic surface efflux measurements is 60% lower than rates determined from measurements during the summer.

Surface electrical properties experiment. Part 2: Theory of radio-frequency interferometry in geophysical subsurface probing

NASA Technical Reports Server (NTRS)

Kong, J. A.; Tsang, L.

1974-01-01

The radiation fields due to a horizontal electric dipole laid on the surface of a stratified medium were calculated using a geometrical optics approximation, a modal approach, and direct numerical integration. The solutions were obtained from the reflection coefficient formulation and written in integral forms. The calculated interference patterns are compared in terms of the usefulness of the methods used to obtain them. Scattering effects are also discussed and all numerical results for anisotropic and isotropic cases are presented.

Outstanding challenges in the seismological study of volcanic processes: Results from recent U.S. and European community-wide discussion workshops

NASA Astrophysics Data System (ADS)

Roman, D. C.; Rodgers, M.; Mather, T. A.; Power, J. A.; Pyle, D. M.

2014-12-01

Observations of volcanically induced seismicity are essential for eruption forecasting and for real-time and near-real-time warnings of hazardous volcanic activity. Studies of volcanic seismicity and of seismic wave propagation also provide critical understanding of subsurface magmatic systems and the physical processes associated with magma genesis, transport, and eruption. However, desipite significant advances in recent years, our ability to successfully forecast volcanic eruptions and fully understand subsurface volcanic processes is limited by our current understanding of the source processes of volcano-seismic events, the effects on seismic wave propagation within volcanic structures, limited data, and even the non-standardized terminology used to describe seismic waveforms. Progress in volcano seismology is further hampered by inconsistent data formats and standards, lack of state-of-the-art hardware and professional technical staff, as well as a lack of widely adopted analysis techniques and software. Addressing these challenges will not only advance scientific understanding of volcanoes, but also will lead to more accurate forecasts and warnings of hazardous volcanic eruptions that would ultimately save lives and property world-wide. Two recent workshops held in Anchorage, Alaska, and Oxford, UK, represent important steps towards developing a relationship among members of the academic community and government agencies, focused around a shared, long-term vision for volcano seismology. Recommendations arising from the two workshops fall into six categories: 1) Ongoing and enhanced community-wide discussions, 2) data and code curation and dissemination, 3) code development, 4) development of resources for more comprehensive data mining, 5) enhanced strategic seismic data collection, and 6) enhanced integration of multiple datasets (including seismicity) to understand all states of volcano activity through space and time. As presented sequentially above, these steps can be regarded as a road map for galvanizing and strengthening the volcano seismological community to drive new scientific and technical progress over the next 5-10 years.

El Nino and the Global Ocean Observing System

NASA Technical Reports Server (NTRS)

Halpern, David

1999-01-01

Until a decade ago, an often-quoted expression in oceanography is that very few observations are recorded throughout the ocean. Now, the sentiment is no longer valid in the uppermost 10% of the tropical Pacific Ocean nor at the surface of the global ocean. One of the remarkable legacies of the 1985-1994 Tropical Oceans Global Atmosphere (TOGA) Program is an in situ marine meteorological and upper oceanographic measurement array throughout the equatorial Pacific to monitor the development and maintenance of El Nino episodes. The TOGA Observing System, which initially consisted of moored- and drifting-buoy arrays, a network of commercial ships, and coastal and island stations, now includes a constellation of satellites and data-assimilating models to simulate subsurface oceanographic conditions. The El Nino and La Nina tropical Pacific Ocean observing system represents the initial phase of an integrated global ocean observing system. Remarkable improvements have been made in ocean model simulation of subsurface currents, but some problems persist. For example, the simulation of the South Equatorial Current (SEC) remains an important challenge in the 2S-2N Pacific equatorial wave guide. During El Nino the SEC at the equator is reduced and sometimes the direction is reversed, becoming eastward. Both conditions allow warm water stored in the western Pacific to invade the eastern region, creating an El Nino episode. Assimilation of data is a tenet of faith to correct simulation errors caused by deficiencies in surface fluxes (especially wind stress) and parameterizations of subgrid-scale physical processes. In the first of two numerical experiments, the Pacific SEC was simulated with and without assimilation of subsurface temperature data. Along the equator, a very weak SEC occurred throughout the eastern Pacific, independent of assimilation of data. However, as displayed in the diagram, in the western Pacific there was no satisfactory agreement between the two simulations. To help determine reliability of the simulated SEC in the western Pacific, current measurements recorded during the 9-19 October 1994 voyage of the French research vessel L'Atalante are also shown in the diagram. With data assimilation, the simulated SEC was in much better agreement with L'Atalante observations. The simulated SEC with data assimilation was far from perfect, in part because of the sparsity of subsurface temperature observations. In the next experiment, TOPEX/POSEIDON sea surface height data in combination with subsurface temperatures will be assimilated to assess further improvement of the simulation of the SEC.

Effect of subalpine canopy removal on snowpack, soil solution, and nutrient export, Fraser Experimental Forest, CO

USGS Publications Warehouse

Stottlemyer, R.; Troendle, C.A.

1999-01-01

Research on the effects of vegetation manipulation on snowpack, soil water, and streamwater chemistry and flux has been underway at the Fraser Experimental Forest (FEF), CO, since 1982. Greater than 95% of FEF snowmelt passes through watersheds as subsurface flow where soil processes significantly alter meltwater chemistry. To better understand the mechanisms accounting for annual variation in watershed streamwater ion concentration and flux with snowmelt, we studied subsurface water flow, its ion concentration, and flux in conterminous forested and clear cut plots. Repetitive patterns in subsurface flow and chemistry were apparent. Control plot subsurface flow chemistry had the highest ion concentrations in late winter and fall. When shallow subsurface flow occurred, its Ca2+, SO42-, and HCO3- concentrations were lower and K+ higher than deep flow. The percentage of Ca2+, NO3-, SO42-, and HCO3- flux in shallow depths was less and K+ slightly greater than the percentage of total flow. Canopy removal increased precipitation reaching the forest floor by about 40%, increased peak snowpack water equivalent (SWE) > 35%, increased the average snowpack Ca2+, NO3-, and NH4+ content, reduced the snowpack K+ content, and increased the runoff four-fold. Clear cutting doubled the percentage of subsurface flow at shallow depths, and increased K+ concentration in shallow subsurface flow and NO3- concentrations in both shallow and deep flow. The percentage change in total Ca2+, SO42-, and HCO3- flux in shallow depths was less than the change in water flux, while that of K+ and NO3- flux was greater. Relative to the control, in the clear cut the percentage of total Ca2+ flux at shallow depths increased from 5 to 12%, SO42- 5.4 to 12%, HCO3- from 5.6 to 8.7%, K+ from 6 to 35%, and NO3- from 2.7 to 17%. The increases in Ca2+ and SO42- flux were proportional to the increase in water flux, the flux of HCO3- increased proportionally less than water flux, and NO3- and K+ were proportionally greater than water flux. Increased subsurface flow accounted for most of the increase in non-limiting nutrient loss. For limiting nutrients, loss of plant uptake and increased shallow subsurface flow accounted for the greater loss. Seasonal ion concentration patterns in streamwater and subsurface flow were similar.Research on the effects of vegetation manipulation on snowpack, soil water, and streamwater chemistry and flux has been underway at the Fraser Experimental Forest (FEF), CO, since 1982. Greater than 95% of FEF snowmelt passes through watersheds as subsurface flow where soil processes significantly alter meltwater chemistry. To better understand the mechanisms accounting for annual variation in watershed streamwater ion concentration and flux with snowmelt, we studied subsurface water flow, its ion concentration, and flux in conterminous forested and clear cut plots. Repetitive patterns in subsurface flow and chemistry were apparent. Control plot subsurface flow chemistry had the highest ion concentrations in late winter and fall. When shallow subsurface flow occurred, its Ca2+, SO42-, and HCO3- concentrations were lower and K+ higher than deep flow. The percentage of Ca2+, NO3-, SO42-, and HCO3- flux in shallow depths was less and K+ slightly greater than the percentage of total flow. Canopy removal increased precipitation reaching the forest floor by about 40%, increased peak snowpack water equivalent (SWE) > 35%, increased the average snowpack Ca2+, NO3-, and NH4+ content, reduced the snowpack K+ content, and increased the runoff four-fold. Clear cutting doubled the percentage of subsurface flow at shallow depths, and increased K+ concentration in shallow subsurface flow and NO3- concentrations in both shallow and deep flow. The percentage change in total Ca2+, SO42-, and HCO3- flux in shallow depths was less than the change in water flux, while that of K+ and NO3- flux was greater. Relative to the control, in the clear cut the percentage of total Ca

A new approach to define surface/sub-surface transition in gravel beds

NASA Astrophysics Data System (ADS)

Haynes, Heather; Ockelford, Anne-Marie; Vignaga, Elisa; Holmes, William

2012-12-01

The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/ sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g., laser displacement scanning), material opacity has precluded the full 3D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides magnetic resonance imaging (MRI) data of vertical bed porosity profiles. Uniform and bimodal (σ g = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.

Environmental Assessment for Selection and Operation of the Proposed Field Research Centers for the Natural and Accelerated Bioremediation Research (NABIR) Program

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

N /A

2000-04-18

The US Department of Energy (DOE) Office of Biological and Environmental Research (OBER), within the Office of Science (SC), proposes to add a Field Research Center (FRC) component to the existing Natural and Accelerated Bioremediation Research (NABIR) Program. The NABIR Program is a ten-year fundamental research program designed to increase the understanding of fundamental biogeochemical processes that would allow the use of bioremediation approaches for cleaning up DOE's contaminated legacy waste sites. An FRC would be integrated with the existing and future laboratory and field research and would provide a means of examining the fundamental biogeochemical processes that influence bioremediationmore » under controlled small-scale field conditions. The NABIR Program would continue to perform fundamental research that might lead to promising bioremediation technologies that could be demonstrated by other means in the future. For over 50 years, DOE and its predecessor agencies have been responsible for the research, design, and production of nuclear weapons, as well as other energy-related research and development efforts. DOE's weapons production and research activities generated hazardous, mixed, and radioactive waste products. Past disposal practices have led to the contamination of soils, sediments, and groundwater with complex and exotic mixtures of compounds. This contamination and its associated costs and risks represents a major concern to DOE and the public. The high costs, long duration, and technical challenges associated with remediating the subsurface contamination at DOE sites present a significant need for fundamental research in the biological, chemical, and physical sciences that will contribute to new and cost-effective solutions. One possible low-cost approach for remediating the subsurface contamination of DOE sites is through the use of a technology known as bioremediation. Bioremediation has been defined as the use of microorganisms to biodegrade or biotransform hazardous organic contaminants to environmentally safe levels in soils, subsurface materials, water, sludges, and residues.. While bioremediation technology is promising, DOE managers and non-DOE scientists have recognized that the fundamental scientific information needed to develop effective bioremediation technologies for cleanup of the legacy waste sites is lacking in many cases. DOE believes that field-based research is needed to realize the full potential of bioremediation. The Department of Energy faces a unique set of challenges associated with cleaning up waste at its former weapons production and research sites. These sites contain complex mixtures of contaminants in the subsurface, including radioactive compounds. In many cases, the fundamental field-based scientific information needed to develop safe and effective remediation and cleanup technologies is lacking. DOE needs fundamental research on the use of microorganisms and their products to assist DOE in the decontamination and cleanup of its legacy waste sites. The existing NABIR program to-date has focused on fundamental scientific research in the laboratory. Because subsurface hydrologic and geologic conditions at contaminated DOE sites cannot easily be duplicated in a laboratory, however, the DOE needs a field component to permit existing and future laboratory research results to be field-tested on a small scale in a controlled outdoor setting. Such field-testing needs to be conducted under actual legacy waste field conditions representative of those that DOE is most in need of remediating. Ideally, these field conditions should be as representative as practicable of the types of subsurface contamination conditions that resulted from legacy wastes from the nuclear weapons program activities. They should also be representative of the types of hydrologic and geologic conditions that exist across the DOE complex.« less

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.

4D ERT Monitoring of Subsurface Water Pipe Leakage During a Controlled Field Experiment

NASA Astrophysics Data System (ADS)

Inauen, C.; Chambers, J. E.; Wilkinson, P. B.; Meldrum, P.; Swift, R. T.; Uhlemann, S.; Gunn, D.; Dashwood, B.; Taxil, J.; Curioni, G.

2016-12-01

Locating and delineating leakage from subsurface pipelines is an important task for civil engineers. 4D Electrical Resistivity Tomography (ERT) allows changes in subsurface resistivity to be imaged at a high spatial and temporal resolution in a minimally invasive manner. It is therefore a promising tool to supplement conventional point-sensing techniques to monitor subsurface flow processes. To assess the efficacy of ERT for pipe leakage monitoring several controlled leak experiments were carried out at a test site in Blagdon, Bristol, UK. To simulate the leak, a plastic pipe with a hole was buried below a flat, grassed area at a depth of 0.7 m, representing a standard UK mains water pipe installation. The water table at the site lies well below the surface meaning that the experiment took entirely place in the vadose zone, where changes in resistivity are primarily sensitive to water content variations. The ERT array covered an area of 6.5m x 6.5m around the leak location. Data acquisition was carried out with the BGS PRIME (Proactive Infrastructure Monitoring and Evaluation) system, which facilitates remote scheduling and autonomous ERT data collection and transmission. To obtain the resistivity changes of the subsurface a 4D inversion was carried out using a Gauss-Newton approach with spatial and temporal smoothness constraints. We were able to reliably observe the onset, spread and cessation of the leakage. Measurements from in-situ soil sensors at several depths above and below the leak complemented the ERT data and allowed us to assess their reliability and directly relate them to hydrogeological processes. Moreover, through experimental tests with soil samples from the test area, a Waxman-Smits relation was obtained to directly convert the changes in electrical resistivity to gravimetric soil moisture content. With future experiments on the test site more work is planned towards survey optimization, automated processing and tracking of leakage plumes.

Evaluation of SCS-CN method using a fully distributed physically based coupled surface-subsurface flow model

NASA Astrophysics Data System (ADS)

Shokri, Ali

2017-04-01

The hydrological cycle contains a wide range of linked surface and subsurface flow processes. In spite of natural connections between surface water and groundwater, historically, these processes have been studied separately. The current trend in hydrological distributed physically based model development is to combine distributed surface water models with distributed subsurface flow models. This combination results in a better estimation of the temporal and spatial variability of the interaction between surface and subsurface flow. On the other hand, simple lumped models such as the Soil Conservation Service Curve Number (SCS-CN) are still quite common because of their simplicity. In spite of the popularity of the SCS-CN method, there have always been concerns about the ambiguity of the SCS-CN method in explaining physical mechanism of rainfall-runoff processes. The aim of this study is to minimize these ambiguity by establishing a method to find an equivalence of the SCS-CN solution to the DrainFlow model, which is a fully distributed physically based coupled surface-subsurface flow model. In this paper, two hypothetical v-catchment tests are designed and the direct runoff from a storm event are calculated by both SCS-CN and DrainFlow models. To find a comparable solution to runoff prediction through the SCS-CN and DrainFlow, the variance between runoff predictions by the two models are minimized by changing Curve Number (CN) and initial abstraction (Ia) values. Results of this study have led to a set of lumped model parameters (CN and Ia) for each catchment that is comparable to a set of physically based parameters including hydraulic conductivity, Manning roughness coefficient, ground surface slope, and specific storage. Considering the lack of physical interpretation in CN and Ia is often argued as a weakness of SCS-CN method, the novel method in this paper gives a physical explanation to CN and Ia.

An integrated approach for estimation of methane emissions from wetlands and lakes in high latitude regions

NASA Astrophysics Data System (ADS)

Chiu, C.; Bowling, L. C.; Podest, E.; Bohn, T. J.; Lettenmaier, D. P.; Schroeder, R.; McDonald, K. C.

2009-04-01

In recent years, there has been increasing evidence of significant alteration in the extent of lakes and wetlands in high latitude regions due in part to thawing permafrost, as well as other changes governing surface and subsurface hydrology. Methane is a 23 times more efficient greenhouse gas than carbon dioxide; changes in surface water extent, and the associated subsurface anaerobic conditions, are important controls on methane emissions in high latitude regions. Methane emissions from wetlands vary substantially in both time and space, and are influenced by plant growth, soil organic matter decomposition, methanogenesis, and methane oxidation controlled by soil temperature, water table level and net primary productivity (NPP). The understanding of spatial and temporal heterogeneity of surface saturation, thermal regime and carbon substrate in northern Eurasian wetlands from point measurements are limited. In order to better estimate the magnitude and variability of methane emissions from northern lakes and wetlands, we present an integrated assessment approach based on remote sensing image classification, land surface modeling and process-based ecosystem modeling. Wetlands classifications based on L-band JERS-1 SAR (100m) and ALOS PALSAR (~30m) are used together with topographic information to parameterize a lake and wetland algorithm in the Variable Infiltration Capacity (VIC) land surface model at 25 km resolution. The enhanced VIC algorithm allows subsurface moisture exchange between surface water and wetlands and includes a sub-grid parameterization of water table position within the wetland area using a generalized topographic index. Average methane emissions are simulated by using the Walter and Heimann methane emission model based on temporally and spatially varying soil temperature, net primary productivity and water table generated from the modified VIC model. Our five preliminary study areas include the Z. Dvina, Upper Volga, Yeloguy, Syum, and Chaya river basins. The temporally-variable inundation extent simulated by the VIC model is compared to 25 km resolution inundation products developed from combined QuikSCAT, AMSR-E and MODIS data sets covering the time period from 2002 onward. The seasonal variation in methane emissions associated with sub-grid variability in water table extent is explored between 1948 and 2006. This work was carried out at Purdue University, at the University of Washington, and at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the NASA.

Final technical report for project titled Quantitative Characterization of Cell Aggregation/Adhesion as Predictor for Distribution and Transport of Microorganisms in Subsurface Environment

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

Gu, April Z.; Wan, Kai-tak

This project aims to explore and develop enabling methodology and techniques for nano-scale characterization of microbe cell surface contact mechanics, interactions and adhesion quantities that allow for identification and quantification of indicative properties related to microorganism migration and transport behavior in porous media and in subsurface environments. Microbe transport has wide impact and therefore is of great interest in various environmental applications such as in situ or enhanced subsurface bioremediation,filtration processes for water and wastewater treatments and protection of drinking water supplies. Although great progress has been made towards understanding the identities and activities of these microorganisms in the subsurface,more » to date, little is known of the mechanisms that govern the mobility and transport of microorganisms in DOE’s contaminated sites, making the outcomes of in situ natural attenuation or contaminant stability enhancement unpredictable. Conventionally, movement of microorganisms was believed to follows the rules governing solute (particle) transport. However, recent studies revealed that cell surface properties, especially those pertaining to cell attachment/adhesion and aggregation behavior, can cause the microbe behavior to deviate from non-viable particles and hence greatly influence the mobility and distribution of microorganisms in porous media.This complexity highlights the need to obtain detailed information of cell-cell and cell-surface interactions in order to improve and refine the conceptual and quantitative model development for fate and transport of microorganisms and contaminant in subsurface. Traditional cell surface characterization methods are not sufficient to fully predict the deposition rates and transport behaviors of microorganism observed. A breakthrough of methodology that would allow for quantitative and molecular-level description of intrinsic cell surface properties indicative for cell-surface interactions is essential for the field. To tackle this, we have developed a number of new Bio-nanomechanical techniques, including reflection interference contrast microscopy (RICM) and bio-AFM (Atomic Force Microscopy), for cell adhesion-detachment measurement of the long-range surface interactions, in combination with mathematical modeling, which would allow us to characterize the mechanical behavior from single cell to multi-cell aggregate, critical thresholds for large scale coaggregation and transportation of cells and aggregates in the presence of long range inter-surface forces etc. Although some technical and mathematical challenges remain, the preliminary results promise great breakthrough potential. In this study, we investigated the cellular surface characteristics of representative bio-remediating microorganisms relevant to DOE IFRC (Integrated Field-Scale Subsurface Research Challenges) sites and their transport behaviors in porous media, aiming to draw a groundbreaking correlation between the micro-scale genetic and biological origin-based cell surface properties, the consequent mechanical adhesion and aggregation behaviors, and the macro-scale microbial mobility and retention in porous media, which are unavailable in the literature. The long-term goal is to significantly improve the mechanistic and quantitative understanding of microbial mobility, sorption, and transport within reactive transport models as needed to manipulate subsurface contaminant fate and transport predictions.« less

Profilometry and subsurface imaging in point of care diagnosis in ocular disease and lymphedema after breast cancer treatment

NASA Astrophysics Data System (ADS)

Sayegh, Samir I.; Taghian, Alphonse

2013-03-01

Breast cancer-related lymphedema (BCRL) can be irreversible with profound negative impact on patients' quality of life. Programs that provide screening and active surveillance for BCRL are essential to determine whether early detection and intervention influences the course of lymphedema development. Established methods of quantitatively assessing lymphedema at early stages include "volume" methods such as perometry and bioimpedance spectroscopy. Here we demonstrate 1) Use of topographical techniques analogous to those used in corneal topography 2) Development of point-of-care lymphedema detection and characterization based on off-the-shelf hardward 3) The role of subsurface imaging 4) Multimodal diagnostics and integration yielding higher sensitivity/ specificity.

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.

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.

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.

Quantifying shallow subsurface water and heat dynamics using coupled hydrological-thermal-geophysical inversion

DOE PAGES

Tran, Anh Phuong; Dafflon, Baptiste; Hubbard, Susan S.; ...

2016-04-25

Improving our ability to estimate the parameters that control water and heat fluxes in the shallow subsurface is particularly important due to their strong control on recharge, evaporation and biogeochemical processes. The objectives of this study are to develop and test a new inversion scheme to simultaneously estimate subsurface hydrological, thermal and petrophysical parameters using hydrological, thermal and electrical resistivity tomography (ERT) data. The inversion scheme-which is based on a nonisothermal, multiphase hydrological model-provides the desired subsurface property estimates in high spatiotemporal resolution. A particularly novel aspect of the inversion scheme is the explicit incorporation of the dependence of themore » subsurface electrical resistivity on both moisture and temperature. The scheme was applied to synthetic case studies, as well as to real datasets that were autonomously collected at a biogeochemical field study site in Rifle, Colorado. At the Rifle site, the coupled hydrological-thermal-geophysical inversion approach well predicted the matric potential, temperature and apparent resistivity with the Nash-Sutcliffe efficiency criterion greater than 0.92. Synthetic studies found that neglecting the subsurface temperature variability, and its effect on the electrical resistivity in the hydrogeophysical inversion, may lead to an incorrect estimation of the hydrological parameters. The approach is expected to be especially useful for the increasing number of studies that are taking advantage of autonomously collected ERT and soil measurements to explore complex terrestrial system dynamics.« less

Discharge-nitrate data clustering for characterizing surface-subsurface flow interaction and calibration of a hydrologic model

NASA Astrophysics Data System (ADS)

Shrestha, R. R.; Rode, M.

2008-12-01

Concentration of reactive chemicals has different chemical signatures in baseflow and surface runoff. Previous studies on nitrate export from a catchment indicate that the transport processes are driven by subsurface flow. Therefore nitrate signature can be used for understanding the event and pre-event contributions to streamflow and surface-subsurface flow interactions. The study uses flow and nitrate concentration time series data for understanding the relationship between these two variables. Unsupervised artificial neural network based learning method called self organizing map is used for the identification of clusters in the datasets. Based on the cluster results, five different pattern in the datasets are identified which correspond to (i) baseflow, (ii) subsurface flow increase, (iii) surface runoff increase, (iv) surface runoff recession, and (v) subsurface flow decrease regions. The cluster results in combination with a hydrologic model are used for discharge separation. For this purpose, a multi-objective optimization tool NSGA-II is used, where violation of cluster results is used as one of the objective functions. The results show that the use of cluster results as supplementary information for the calibration of a hydrologic model gives a plausible simulation of subsurface flow as well total runoff at the catchment outlet. The study is undertaken using data from the Weida catchment in the North-Eastern Germany, which is a sub-catchment of the Weisse Elster river in the Elbe river basin.

Optical method and apparatus for detection of surface and near-subsurface defects in dense ceramics

DOEpatents

Ellingson, W.A.; Brada, M.P.

1995-06-20

A laser is used in a non-destructive manner to detect surface and near-subsurface defects in dense ceramics and particularly in ceramic bodies with complex shapes such as ceramic bearings, turbine blades, races, and the like. The laser`s wavelength is selected based upon the composition of the ceramic sample and the laser can be directed on the sample while the sample is static or in dynamic rotate or translate motion. Light is scattered off surface and subsurface defects using a preselected polarization. The change in polarization angle is used to select the depth and characteristics of surface/subsurface defects. The scattered light is detected by an optical train consisting of a charge coupled device (CCD), or vidicon, television camera which, in turn, is coupled to a video monitor and a computer for digitizing the image. An analyzing polarizer in the optical train allows scattered light at a given polarization angle to be observed for enhancing sensitivity to either surface or near-subsurface defects. Application of digital image processing allows subtraction of digitized images in near real-time providing enhanced sensitivity to subsurface defects. Storing known ``feature masks`` of identified defects in the computer and comparing the detected scatter pattern (Fourier images) with the stored feature masks allows for automatic classification of detected defects. 29 figs.

Synthesis of integrated primary production in the Arctic Ocean: II. In situ and remotely sensed estimates

NASA Astrophysics Data System (ADS)

Hill, Victoria J.; Matrai, Patricia A.; Olson, Elise; Suttles, S.; Steele, Mike; Codispoti, L. A.; Zimmerman, Richard C.

2013-03-01

Recent warming of surface waters, accompanied by reduced ice thickness and extent may have significant consequences for climate-driven changes of primary production (PP) in the Arctic Ocean (AO). However, it has been difficult to obtain a robust benchmark estimate of pan-Arctic PP necessary for evaluating change. This paper provides an estimate of pan-Arctic PP prior to significant warming from a synthetic analysis of the ARCSS-PP database of in situ measurements collected from 1954 to 2007 and estimates derived from satellite-based observations from 1998 to 2007. Vertical profiles of in situ chlorophyll a (Chl a) and PP revealed persistent subsurface peaks in biomass and PP throughout the AO during most of the summer period. This was contradictory with the commonly assumed exponential decrease in PP with depth on which prior satellite-derived estimates were based. As remotely sensed Chl a was not a good predictor of integrated water column Chl a, accurate satellite-based modeling of vertically integrated primary production (IPPsat), requires knowledge of the subsurface distribution of phytoplankton, coincident with the remotely sensed ocean color measurements. We developed an alternative approach to modeling PP from satellite observations by incorporating climatological information on the depths of the euphotic zone and the mixed layer that control the distribution of phytoplankton that significantly improved the fidelity of satellite derived PP to in situ observations. The annual IPP of the Arctic Ocean combining both in situ and satellite based estimates was calculated here to be a minimum of 466 ± 94 Tg C yr-1 and a maximum of 993 ± 94 Tg C yr-1, when corrected for subsurface production. Inflow shelf seas account for 75% of annual IPP, while the central basin and Beaufort northern sea were the regions with the lowest annual integrated productivity, due to persistently stratified, oligotrophic and ice-covered conditions. Although the expansion of summertime ice retreat should stimulate photosynthesis by exposing more of the AO to solar irradiance, total PP is ultimately limited by nutrient availability. Therefore, changes in AO PP will be forced by the balance between stratification and mixing, the effects of which are not yet quantified.

Mars Sulfate Formation Sourced in Sulfide-Enriched Subsurface Fluids: The Rio Tinto Model

NASA Technical Reports Server (NTRS)

Fernandez-Remolar, D. C.; Prieto-Ballesteros, O.; Osburn, M. R.; Gomez-Ortiz, D.; Arvidson, R. E.; Morris, R. V.; Ming, D.; Amils, R.; Friendlander, L. R.

2007-01-01

The extensive evidence for sulfate deposits on Mars provided by analyses of MER and Mars Express data shows that the sulfur played an essential role in the geochemical cycles of the planet, including reservoirs in the atmosphere, hydro-sphere and geosphere. Overall the data are consistent with a fluvial/lacustrine-evaporative origin of at least some of the sulfate deposits, with mineral precipitation through oversaturation of salty acidic fluids enriched in sulfates. This scenario requires reservoirs of sulfur and associated cations, as well as an acidic and oxidizing hydrochemistry which could be provided by surface and subsurface catching of meteoric waters resulting in the presence of sulfur-bearing gases and steam photochemistry. In this work we suggest a new scenario for the extensive generation of sulfates in Mars based on the observation of seasonal changes in the redox and pH of subsurface waters enriched in sulfur that supply the acidic Mars process analog of Rio Tinto. This model considers the long-term subsurface storage of sulfur during most of Noachian and its release from the late Noachian to Hesperian time through weathering by meteoric fluids that would acidify and oxidize the sulfur bearing compounds stored in the subsurface.

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.

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.

Use of an optical clearing agent to enhance the visibility of subsurface structures and lesions from tooth occlusal surfaces

PubMed Central

Kang, Hobin; Darling, Cynthia L.; Fried, Daniel

2016-01-01

Abstract. The purpose of this study is to show that optical clearing agents can be used to increase the visibility of deeply penetrating occlusal lesions that have reached the underlying dentin and spread laterally under the enamel. Previous studies have shown that high refractive index fluids can increase the contrast of caries lesions. Extracted teeth with natural occlusal lesions were imaged with optical coherence tomography (OCT) with and without the addition of a transparent vinyl polysiloxane impression material (VPS) currently used in vivo. The relative intensity of the reflectivity from the underlying lesion area for each sample was measured before and after application of the VPS. Lesion presence was confirmed with polarized light microscopy and microradiography. Application of VPS significantly increased (P<0.0001) the integrated reflectivity of subsurface dentinal lesions. This study shows that optical clearing agents can be used to increase the optical penetration and the visibility of subsurface lesions and the dentinal–enamel junction under sound and demineralized enamel in OCT images. PMID:27071709

Correlation of Resistivity Value with Geotechnical N-Value of Sedimentary Area in Nusajaya, Johor, Malaysia

NASA Astrophysics Data System (ADS)

Akip Tan, S. N. Mohd; Edy Tonnizam, M.; Saad, R.; Dan, M. F. Md; Nordiana, M. M.; Hazreek, Z. A. M.; Madun, A.

2018-04-01

Electrical resistivity survey and the geotechnical SPT blow counts (N-value) were carried out simultaneously on the tropically weathered sedimentary rock mass for an excavation project at Nusajaya, Johor, Malaysia. This study aims to determine subsurface profile by using 2D-resistivity methods and correlate with N-value derived from boring works. Four boreholes were investigated in five survey lines that revealed the site is underlain by moderately to completely weathered sandstone, clay, silt and shale. Data analysis from 2D-resistivity image shows that zones with high resistivity value generally have high N-value, and vice versa. Five zones have inversed the proportional relation between N-value and resistivity Ωm value due to different types of soil lithology. It indicates that 2D-resistivity is significance to detect bodies of anomalous materials or estimating the depth of bedrock. As a conclusion, the integration of geophysical and geotechnical analysis provides a promise approach to understand some relationship concerning the subsurface subsurface ground through the combination of 2D-resistivity and N-value.

Integrated approach for demarcating subsurface pollution and saline water intrusion zones in SIPCOT area: a case study from Cuddalore in Southern India.

PubMed

Sankaran, S; Sonkamble, S; Krishnakumar, K; Mondal, N C

2012-08-01

This paper deals with a systematic hydrogeological, geophysical, and hydrochemical investigations carried out in SIPCOT area in Southern India to demarcate groundwater pollution and saline intrusion through Uppanar River, which flows parallel to sea coast with high salinity (average TDS 28, 870 mg/l) due to back waters as well as discharge of industrial and domestic effluents. Hydrogeological and geophysical investigations comprising topographic survey, self-potential, multi-electrode resistivity imaging, and water quality monitoring were found the extent of saline water intrusion in the south and pockets of subsurface pollution in the north of the study area. Since the area is beset with highly permeable unconfined quaternary alluvium forming potential aquifer at shallow depth, long-term excessive pumping and influence of the River have led to lowering of the water table and degradation of water quality through increased salinity there by generating reversal of hydraulic gradient in the south. The improper management of industrial wastes and left over chemicals by closed industries has led surface and subsurface pollution in the north of the study area.

The Serpentinite Subsurface Microbiome

NASA Astrophysics Data System (ADS)

Schrenk, M. O.; Nelson, B. Y.; Brazelton, W. J.

2011-12-01

Microbial habitats hosted in ultramafic rocks constitute substantial, globally-distributed portions of the subsurface biosphere, occurring both on the continents and beneath the seafloor. The aqueous alteration of ultramafics, in a process known as serpentinization, creates energy rich, high pH conditions, with low concentrations of inorganic carbon which place fundamental constraints upon microbial metabolism and physiology. Despite their importance, very few studies have attempted to directly access and quantify microbial activities and distributions in the serpentinite subsurface microbiome. We have initiated microbiological studies of subsurface seeps and rocks at three separate continental sites of serpentinization in Newfoundland, Italy, and California and compared these results to previous analyses of the Lost City field, near the Mid-Atlantic Ridge. In all cases, microbial cell densities in seep fluids are extremely low, ranging from approximately 100,000 to less than 1,000 cells per milliliter. Culture-independent analyses of 16S rRNA genes revealed low-diversity microbial communities related to Gram-positive Firmicutes and hydrogen-oxidizing bacteria. Interestingly, unlike Lost City, there has been little evidence for significant archaeal populations in the continental subsurface to date. Culturing studies at the sites yielded numerous alkaliphilic isolates on nutrient-rich agar and putative iron-reducing bacteria in anaerobic incubations, many of which are related to known alkaliphilic and subsurface isolates. Finally, metagenomic data reinforce the culturing results, indicating the presence of genes associated with organotrophy, hydrogen oxidation, and iron reduction in seep fluid samples. Our data provide insight into the lifestyles of serpentinite subsurface microbial populations and targets for future quantitative exploration using both biochemical and geochemical approaches.

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.

Dissolved organic carbon loading from the field to watershed scale in tile-drained landscapes

USDA-ARS?s Scientific Manuscript database

Dissolved organic carbon (DOC) is an integral part to the functioning of aquatic ecosystems; yet, there is a paucity of data on DOC delivery and management in tile-drained agricultural headwater watersheds. The objective of this study was to quantify the contribution of subsurface tile drains to wat...

In-situ Substrate Addition to Create Reactive Zones for Treatment of Chlorinated Aliphatic Hydrocarbons: Hanscom Air Force Base

DTIC Science & Technology

2003-04-04

processes in the subsurface. This substrate is typically molasses although these substrates can include high fructose corn syrup , whey, etc. (Suthersan...typically comprised of a carbohydrate such as molasses, whey, high fructose corn syrup , lactate, butyrate, or benzoate). Through periodic subsurface...this purpose; other carbohydrates such as high fructose corn syrup and whey can also be effective. This approach has been accepted by regulators and

Proof-of-feasibility of using well bore deformation as a diagnostic tool to improve CO 2 sequestration

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

Murdoch, Larry; Moysey, Stephen; Germanovich, Leonid

Injecting CO 2 raises pore pressure and this causes subsurface formations to deform. The pattern and amount of deformation will reflect the distribution of pressure and formation properties in the subsurface, two quantities of interest during CO 2 storage. The hypothesis underlying this research is that the small deformation accompanying CO 2 storage can be measured and interpreted to improve the storage process.