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All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Computational Tools and Workflows for Quantitative Risk Assessment and Decision Support for Geologic Carbon Storage Sites: Progress and Insights from the U.S. DOE’s National Risk Assessment Partnership

The 2005 Intergovernmental Panel on Climate Change (IPCC) Special Report on CCS raised the profile of CO2 capture and storage (CCS) as an important technology for reducing greenhouse gas (GHG) emissions. CCS is now recognized as a key component of most climate change mitigation scenarios. Since publication of that report the international research, development, and deployment (RD&D) community has advanced key technical aspects, clarified regulatory requirements, explored value chain and infrastructure solutions, and developed incentive paradigms to enable and promote large-scale deployment of CCS. These efforts have included research to better characterize geologic storage resources, to improve injection performance and storage efficiency, to assess and manage subsurface environmental risks, and to advance monitoring technologies to assure system conformance. These efforts have helped to build confidence in the viability of geologic carbon storage (GCS), but stakeholder concerns about long-term risks and liability associated with GCS remain a hurdle to broad acceptance and large-scale deployment of CCS. Since 2010, the U.S. DOE’s National Risk Assessment Partnership (NRAP) – a research collaboration between five contributing national laboratories – has worked to establish and demonstrate methods and tools to quantify and manage the subsurface environmental risks associated with GCS, amidst uncertainty. This work supports the Office of Fossil Energy and Carbon Management Carbon Transport and Storage Program’s goal of advancing safe and secure commercial-scale GCS deployment. To address the technical challenge of simulating the physical response of the GCS site to large-scale CO2 injection, NRAP has adopted an approach that relies on coupling computationally efficient reduced-order and/or data-driven proxy models of important system components (i.e., storage reservoir, sealing caprock, leakage pathways, intermediate formations, overlying groundwater aquifers, and the atmosphere) in integrated assessment framework. That integrated model of the physical system is complemented with fit-for purpose functionality to support site characterization and risk-related decisions. The recently released NRAP Phase II toolset includes the Open-Source Integrated Assessment Model (NRAP-Open-IAM) for evaluation of trends in leakage risk and potential impact, tools to support monitoring design optimization (Designs for Risk Evaluation and Management – DREAM v3.0 and Passive Seismic Monitoring Tool - PSMT), and tools for state of stress evaluation (State-of-Stress Analysis Tool - SOSAT) and forecasting induced seismicity risk. The NRAP team has also released a pair of reports describing conceptual workflows to incorporate physics-based, quantitative risk assessment into many of the design, planning, operation, and closure decisions for GCS projects. An online catalogue highlights published studies where these tools and methods are demonstrated. In this presentation, the utility of these products to assess risks and address key stakeholder questions will be highlighted through examples, and related insights about the safety and security of geologic carbon storage in qualified storage sites will be discussed. The prospect of rapid, large-scale deployment of GCS technology to aggressively reduce anthropogenic CO2 emissions requires careful consideration of interference between multiple commercial-scale storage projects within a basin. Going forward, NRAP is expanding and adapting site-scale risk quantification tools and methods to enable assessment of risks and inform management decisions for basin-scale deployment. Increasingly, this work will leverage next-generation approaches for surrogate modelling, fast prediction, and advanced visualization enabled by machine learning and artificial intelligence to promote virtual learning, scenario evaluation, and augment risk-based decision making.

quantitative risk assessment, geologic carbon stor↗
NASA NTRS2017

Europa Mission Configuration Update to Accommodate Maturing Instrument Designs

A mission to Jupiter’s moon, Europa has been of interest to NASA and JPL since the Galileo mission's magnetometer data predicted the presence of a subsurface ocean. The planned Europa mission would be equipped with a suite of instruments to perform both remote and in-situ sensing, the scope of which ranges from gravity science to characterizing the surface composition, with one of the objectives being to confirm the existence of the subsurface ocean. As the selected instruments mature, the challenge has been to select and refine a spacecraft configuration that is flexible enough to accommodate these changes without degrading the scientific capability of the spacecraft. An increase in instrument volume and power have prompted the growth of spacecraft engineering subsystems, which include the solar arrays and the avionics module. These changes have the potential to cause obstructions to the instrument fields of view, stray light keep-out-zones, and thermal radiative fields of view. Many of these criteria are addressed by the implementation of a dedicated instrument platform. Payloads that are unique to the Europa mission require new approaches to instrument accommodation, such as coupling the ice penetrating radar's radiating elements to the solar array. This paper will discuss these accommodation strategies for the Europa spacecraft to generate a new baseline design.

Gentile, Matthew↗
NASA NTRS1982

Volumetric analysis of complex lunar craters - Implications for basin ring formation

The crater to basin transition in complex lunar craters is characterized by combining morphological and volumetric analyses of their central peaks with subsurface data from terrestrial complex impact structures which suggest that the amount of uplifted material, as judged from its depth of origin, continues to increase with increasing rim diameter. This latter phenomenon implies that a redistribution of uplifted material away from a centralized peak may occur in the larger craters. The morphological and volumetric changes described occur over a rim diameter range of 51-80 km, which is considerably lower than the previously proposed range for the crater to basin transition of 140-175 km. Evidence is given in support of a crater to basin transition which begins at 51-80 km, and is characterized by a relative reduction in central peak volume and a development of rings of floor roughening which may be precursors of peak ring development.

Hale, W. S.↗
DOE OSTI2023

Data Summary Report for Soil and Slab Sampling at Former Building 175

Lawrence Livermore National Security (LLNS) and the U.S. Department of Energy (DOE) are in the process of returning the area where Building 175 existed to beneficial use for future site development. The completed assessment will help LLNS and DOE to outline project scope and costs associated with the removal, characterization, and disposal of materials generated when the concrete slab for the former building and any associated remaining subsurface structures are demolished. Slab removal under the Transition & Disposition process requires full screening for potential site contamination to determine appropriate future land use. Borehole locations and depths were designed to correctly assess DOE’s future liability for characterizing residual vadose zone contamination. If a residual source area is identified at depth, DOE will need to evaluate the additional cost of future subsurface cleanup (with limited access) due to planned development. This is necessary to leave the location in a “ready-to-build” status. As a result, Phase II sampling requirements may in some cases extend beyond the construction zone required for slab removal to ensure the necessary due diligence. To avoid the potential spread of contamination and/or the creation of an environmental release by impacting the integrity of known contamination areas (e.g., pit within room 102 and the east to west boundary seam), these locations were not sampled for this project. During demolition of the slab, these locations and their underlying soils should be further evaluated. The assessment was conducted in accord with the May 2022 Lawrence Livermore National Laboratory Former Building 175 Assessment Soil Sampling and Analysis Plan / Quality Assurance Plan. Thirty-six, direct-push borings were advanced, along with collecting concrete (where present) and soil samples for laboratory analyses. Thirty-two of the borings were advanced to a depth of 25 feet below ground (bgs), and four borings were advanced to a depth of 55 feet bgs. The concrete slab for former Building 175 ranged from approximately 8 inches to over two feet in thickness. Soils encountered during the investigation consisted primarily of clayey silt, with interbeds of sandy gravel and silty sand to the total depth explored of 55 feet bgs. Field photoionization detector readings – checking for volatile organic compound (VOC) vapors in soils, ranged from zero (0) to a peak of 33 parts per million at 25 feet bgs in boring PC-B175- 028. The cause for the peak reading is unknown, however, no visually discolored or odorous soils were encountered during the assessment and all VOC results were below Lawrence Livermore National Laboratory’s (LLNL’s) Soil Screening and Management Plan (SSMP) soil screening levels (SSL). Groundwater was not encountered during the assessment and is expected to occur at roughly 65 feet bgs in the project area. No metals were detected at concentrations of concern in the concrete core samples collected and analyzed. Low gross alpha and beta activity concentrations were detected in the concrete core samples collected and analyzed. The detected activity concentrations would appear to be from naturally occurring radioactive isotopes, i.e., potassium 40, present in the raw materials used to make concrete and not artificially added. Tritium was not detected above the testing laboratory's Method Detection Limit (MDL) in any of the concrete core samples collected and analyzed. The radioactive isotopes - actinium 228, bismuth 214, lead 212, lead 214, potassium 40, radium 226, radium 228, and thallium 208, were detected at low activity concentrations in the concrete core samples analyzed. Based on the detected activity concentrations, the isotopes would appear to be naturally occurring in the raw materials used to make concrete and not artificially added. Acetone – a common laboratory contaminant, was detected in nine of the soil samples collected and analyzed. Concentrations of two other volatile organic compounds (benzene and tetrachloroethene) were detected in five of the soil samples analyzed. All concentrations were below SSLs. Total petroleum hydrocarbons as diesel range organics were detected at 43.9 milligrams per kilogram (mg/kg) in the 20-foot bgs duplicate sample from boring PC-B175-007. Total petroleum hydrocarbons as motor oil were detected at 7.20 mg/kg in the 15-foot bgs routine sample from boring PC-B175-001, and at 20.7 mg/kg in the 20-foot bgs duplicate sample from boring PC-B175-007. The SSL for diesel-range TPHs is 260 mg/kg. LLNL does not have an SSL for motor oil range TPHs. No indications of a release, e.g., visibly stained, or odorous soil, were present at the boring locations. No samples collected contained polychlorinated biphenyls (PCBs) in concentrations above the laboratory reporting limit. Arsenic was detected above its SSL of 8.51 mg/kg in the 25-foot bgs routine sample collected from boring PC-B175-023. Nickel was detected above its SSL of 86.0 mg/kg in the 10-foot bgs routine sample from boing PC-B175-005, the 20-foot bgs routine sample from boring PC-B175-025, and the 25-foot bgs routine sample from boring PC-B175-034. The detected concentrations, however, were well below ten times (10x) their respective STLCs. Gross alpha and/or gross beta were detected above their respective SSL activity concentrations in three routine soil samples. Retesting (two per sample) of the samples showed that the initial reported activity concentrations were anomalous. Tritium was not detected in any of the routine or duplicate soil samples collected and analyzed during the investigation. The radioactive isotopes - actinium 228, bismuth 212 and 214, lead 212 and 214, potassium 40, radium 224, 226 and 228, thallium 208, thorium 234 and uranium, were detected at low activity concentrations in the soil samples analyzed for radioactive constituents. The detected isotopes and their associated activity concentrations are typical of those naturally occurring in the marine-type sedimentary deposits underlying the Livermore Valley. No radiological controls are necessary for the soil evaluated.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Degradation Diagnostics from the Subsurface of Lithium-Ion Battery Electrodes

Despite the long-established rocking-chair theory of lithium-ion batteries (LIBs), developing novel characterization methodology with higher spatiotemporal resolution facilitates a better understanding of the solid electrolyte interphase studies to shape the reaction mechanisms. In this work, we develop a Xenon ion plasma focused ion beam (Xe + PFIB)-based characterization technique to probe the cross-sectional interface of both ternary cathode and graphite anode electrodes, with the focus on revealing the chemical composition and distribution underneath the electrode surface by in-depth analysis of secondary ions. Particularly, the lithium fluoride is detected in the pristine cathode prior to contact with the electrolyte, reflecting that the electrode degradation is in the form of the loss of lithium inventory during electrode preparation. This degradation is related to the hydrolysis of the cathode material and the decomposition of the PVDF binder. Here, through the quantitative analysis of the transition-metal degradation products, manganese is found to be the dominant element in the newly formed inactive fluoride deposition on the cathode, while no transition metal signal can be found inside the anode electrode. These insights at high resolution implemented via a PFIB-based characterization technique not only enrich the understanding of the degradation mechanism in the LIBs but also identify and enable a high-sensitivity methodology to obtain the chemical survey at the subsurface, which will help remove the capacity-fade observed in most LIBs.

25 ENERGY STORAGE↗
DOE OSTI2024

Shallow Soil Response to a Buried Chemical Explosion With Geophones and Distributed Acoustic Sensing

Abstract Shallow sediments can respond non‐linearly to large dynamic strains and undergo a subsequent healing phase as the material gradually recovers following the passing of seismic waves. This study focuses on the physical changes in the subsurface caused by the shaking from a buried chemical explosion detonated in a borehole in Nevada, USA, as a part of the Source Physics Experiment Phase II. The explosion damaged the shallow subsurface and modified the frequency content recorded by 491 geophones and 2240 Distributed Acoustic Sensing (DAS) channels within 2.5 km from surface ground zero. We observe a gradual shift of resonance frequencies in the 10–25 Hz frequency band in the hours following the explosion and develop a method to characterize the related logarithm‐type healing process of the shallow (i.e., upper ∼25 m) subsurface. We find that stronger levels of ground motion increase the relative degree of damage and duration of the subsurface healing; with the spall region exhibiting the largest degree of damage and longest healing recovery time. We observe coherent spatial patterns of damage with the region located to the southeast of the explosion exhibiting more damage than the southwest region. This study demonstrates that both DAS and co‐located geophones capture similar temporal changes associated with the physical processes occurring in the subsurface, with the high‐density sampling of DAS measurements enabling a new capability to monitor the fine‐scale changes of the Earth's shallow subsurface following the detonation of a buried explosion.

Viens, Loïc↗
DOE OSTI2015

An autotrophic H 2 -oxidizing, nitrate-respiring, Tc(VII)-reducing A cidovorax sp. isolated from a subsurface oxic-anoxic transition zone: H 2 -oxidizing, Tc-reducing Acidovorax spp.

Increasing concentrations of H 2 with depth were observed across a geologic unconformity and associated redox transition zone in the subsurface at the Hanford Site in south-central Washington, USA. An opposing gradient characterized by decreasing O 2 and nitrate concentrations was consistent with microbial-catalyzed biogeochemical processes. Sterile sand was incubated in situ within a multi-level sampler placed across the redox transition zone to evaluate the potential for Tc(VII) reduction and for enrichment of H 2 -oxidizing denitrifiers capable of reducing Tc(VII). H 2 -driven TcO 4- reduction was detected in sand incubated at all depths but was strongest in material from a depth of 17.1 m. Acidovorax spp. were isolated from H 2 -nitrate enrichments from colonized sand from 15.1 m, with one representative, strain JHL-9, subsequently characterized. JHL-9 grew on acetate with either O 2 or nitrate as electron acceptor (data not shown) and on medium with bicarbonate, H 2 and nitrate. JHL-9 also reduced pertechnetate (TcO 4- ) under denitrifying conditions with H 2 as the electron donor. H 2 -oxidizing Acidovorax spp. in the subsurface at Hanford and other locations may contribute to the maintenance of subsurface redox gradients and offer the potential for Tc(VII) reduction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Friction and Wear of Nanoadditive-Based Biolubricants in Steel–Steel Sliding Contacts: A Comparative Study

The present work deals with the study of tribo-pair interaction in lubricated sliding contacts. By considering the environmental issues, the sunflower oil was extracted from the sunflower seeds and used as a base lubricant. The two types of the nanoadditives, i.e., CuO and CeO{sub 2}, varying concentrations from 0.10 to 0.50% w/v were used to formulate the nanolubricants. The compatibility/synergism of the nanoadditives was examined from antifriction and antiwear behavior study with four-ball tester. Also, sunflower oil was modified by the chemical method to improve its fatty acid structure. A comparative tribological and compatibility study was also done in modified oil at similar concentration levels with both types of nanoparticles. The tribological test result exhibits 0.10% w/v concentration of the nanoadditive as optimum due to lowest wear scar and coefficient of friction. Higher concentration of the nanoparticles impaired the base oil performance. Different analytical tools were used to characterize the oil modification and worn surfaces. Moreover, the role of subsurface of the contacting material with the tribological performance has been reported.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

SHASTA-HELP

This tool contains functionality for estimating the storage potential of pure and blended natural gas-hydrogen mixtures in various subsurface formations and is intended to be used for pre-characterization or site screening purposes. Detailed storage analysis should be conducted by full reservoir simulation models.

Hydrogen↗
DOE OSTI2023

Subsurface Hydrogen Assessment, Storage, and Technology Acceleration (SHASTA) - Hydrogen Estimator for Logistical Planning (HELP) User’s Manual

This user’s manual describes version 1.0 of the SHASTA-HELP (Subsurface Hydrogen Assessment, Storage, and Technology Acceleration (SHASTA) - Hydrogen Estimator for Logistical Planning (HELP)) tool and provides instructions for use. The purpose of the SHASTA-HELP tool is to integrate the suite of tools developed by the SHASTA research team in a web-based framework for ease of access and more advanced, integrated analysis. This tool contains functionality for estimating the storage potential of pure and blended natural gas-hydrogen mixtures in various subsurface formations and is intended to be used for pre-characterization or site screening purposes. Detailed storage analysis should be conducted by full reservoir simulation models.

08 HYDROGEN↗
NASA NTRS1988

Processing and redistribution of surface and subsurface samples by impact cratering

As a portion of the Martian surface becomes more densely cratered, the more the surface and subsurface materials become laterally redistributed and impact metamorphosed. Specimen redistribution is characterized as a function of both impact density and original specimen depth, and the impact histories of those specimens are also characterized.

Woronow, A.↗
NASA NTRS2020

Geology of the InSight Landing Site on Mars

The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft landed successfully on Mars and imaged the surface to characterize the surficial geology. Here we report on the geology and subsurface structure of the landing site to aid in situ geophysical investigations. InSight landed in a degraded impact crater in Elysium Planitia on a smooth sandy, granule- and pebble-rich surface with few rocks. Superposed impact craters are common and eolian bedforms are sparse. During landing, pulsed retrorockets modified the surface to reveal a near surface stratigraphy of surficial dust, over thin unconsolidated sand, underlain by a variable thickness duricrust, with poorly sorted, unconsolidated sand with rocks beneath. Impact, eolian, and mass wasting processes have dominantly modified the surface. Surface observations are consistent with expectations made from remote sensing data prior to landing indicating a surface composed of an impact-fragmented regolith overlying basaltic lava flows.

M. Golombek↗
DOE OSTI2015

Radiochemically-supported microbial communities. A potential mechanism for biocolloid production of importance to actinide transport

The work described here revealed the presence of diverse microbial communities located across 19 subsurface sites at the NNSS/NTTR and nearby locations. Overall, the diversity of microorganisms was high for subsurface habitats and variable between sites. As of this writing, preparations are being made to combine the Illumina sequences and 16S rRNA clone libraries with other non-NNSS/NTTR well sites of Southern Nevada Regional Flow System for a publication manuscript describing our very broad landscape scale survey of subsurface microbial diversity. Isolates DRI-13 and DRI-14 remain to be fully characterized and named in accordance with the conventions established by Bergey's Manual of Systematic Bacteriology. In preparation to be published, these microorganisms will be submitted to the American Type Culture Collection (ATCC) and the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ).It is anticipated that the data resulting from this study in combination with other data sets that will allow us to produce a number of publications that will be impactful to the subsurface microbiology community.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Numerical Modeling of Anisotropic Elastic-Wave Sensitivity Propagation for Optimal Design of Time-Lapse Seismic Surveys

Reliable subsurface time-lapse seismic monitoring is crucial for many geophysical applications, such as enhanced geothermal system characterization, geologic carbon utilization and storage, and conventional and unconventional oil/gas reservoir characterization, etc. In this work, we develop an elastic-wave sensitivity propagation method for optimal design of cost-effective time-lapse seismic surveys considering the fact that most of subsurface geologic layers and fractured reservoirs are anisotropic instead of isotropic. For anisotropic media, we define monitoring criteria using qP- and qS-wave sensitivity energies after decomposing qP- and qS-wave components from the total elastic-wave sensitivity wavefield using a hybrid time- and frequency-domain approach. Geophones should therefore be placed at locations with significant qP- and qS-wave sensitivity energies for cost-effective time-lapse seismic monitoring in an anisotropic geology setting. Our numerical modeling results for a modified anisotropic Hess model demonstrate that, compared with the isotropic case, subsurface anisotropy changes the spatial distributions of elastic-wave sensitivity energies. Consequently, it is necessary to consider subsurface anisotropies when designing the spatial distribution of geophones for cost-effective time-lapse seismic monitoring. This finding suggests that it is essential to use our new anisotropic elastic-wave sensitivity modeling method for optimal design of time-lapse seismic surveys to reliably monitor the changes in subsurface reservoirs, fracture zones or target monitoring regions.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Development of HydroImage, A User Friendly Hydrogeophysical Characterization Software

HydroImage, user-friendly software that utilizes high-resolution geophysical data for estimating hydrogeological parameters in subsurface strata, was developed under this grant. HydroImage runs on the personal computer platform to promote broad use by hydrogeologists to further understanding of subsurface processes that govern contaminant fate, transport, and remediation. The unique software provides estimates of hydrogeological properties over continuous volumes of the subsurface, whereas previous approaches only allow estimation of point locations. Thus, this unique tool can be used to significantly enhance site conceptual models and improve design and operation of remediation systems.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Analysis of Potential Leakage Pathways and Mineralization within Caprocks for Geologic Storage of CO 2

We used a multifaceted approach to investigate the nature of caprocks above, and the interface between, reservoir-quality rocks that might serve as targets for carbon storage. Fieldwork in southeastern Utah examined the regional- to m-scale nature of faults and fractures across the sedimentiological interfaces. We also used microscopic analyses and mechanical modeling to examine the question as to how the contacts between units interact, and how fractures may allow fluids to move from reservoirs to caprock. Regional-­scale analyses using ASTER data enabled us to identify location of alteration, which led to site-­specific studies of deformation and fluid flow. In the Jurassic Carmel Formation, a seal for the Navajo Sandstone, we evaluated mesoscale variability in fracture density and morphology and variability in elastic moduli in the Jurassic Carmel Formation, a proposed seal to the underlying Navajo Sandstone for CO 2 geosequestration. By combining mechano-stratigraphic outcrop observations with elastic moduli derived from wireline log data, we characterize the variability in fracture pattern and morphology with the observed variability in rock strength within this heterolithic top seal. Outcrop inventories of discontinuities show fracture densities decrease as bed thickness increases and fracture propagation morphology across lithologic interfaces vary with changing interface type. Dynamic elastic moduli, calculated from wireline log data, show that Young’s modulus varies by up to 40 GPa across depositional interfaces, and by an average of 3 GPa across the reservoir/seal interface. We expect that the mesoscale changes in rock strength will affect the distributions of localized stress and thereby influence fracture propagation and fluid flow behavior within the seal. These data provide a means to closely tie outcrop observations to those derived from subsurface data and estimates of subsurface rock strength. We also studied damage zones associated normal faults in the Permian Cedar Mesa Sandstone, southeastern Utah. These faults are characterized by a single slip surfaces and damage zones containing deformation bands, veins, and joints. Field observations include crosscutting relationships, permeability increase, rock strength decrease, and ultraviolet light induced mineral fluorescence within the damage zone. These field observations combined with the interpreted paragenetic sequence from petrographic analysis, suggests a deformation history of reactivation and several mineralization events in an otherwise low-permeability fault. All deformation bands and veins fluoresce under ultraviolet light, suggesting connectivity and a shared mineralization history. Pre-­existing deformation features act as loci for younger deformation and mineralization events, this fault and its damage zone illustrate the importance of the fault damage zone to subsurface fluid flow. We model a simplified stress history in order to understand the importance of rock properties and magnitude of tectonic stress on the deformation features within the damage zone. The moderate confining pressures, possible variations in pore pressure, and the porous, fine-­grained nature of the Cedar Mesa Sandstone results in a fault damage zone characterized by enhanced permeability, subsurface fluid flow, and mineralization. Structural setting greatly influences fracture spacing and orientation. Three structural settings were examined and include fault proximity, a fold limb of constant dip, and a setting proximal to the syncline hinge. Fracture spacing and dominant fracture orientation vary at each setting and distinctions between regional and local paleo-stress directions can be made. Joints on the fold limb strike normal to the fold axis/bedding and are interpreted to be sub-parallel to the maximum regional paleo-stress direction as there is no fold related strain. Joints proximal to faults and the syncline hinge may have formed under local stress conditions associated with folding and faulting, and in some cases, are perpendicular to the maximum regional paleo-stress direction. Macroscale analyses of the Iron Wash fault, which cuts most of the stratigraphy of the reservoir- seal analogs, reveals that seal bypass occurs along faults with mixed lithologic composition. While portions of the fault may be effective seals, when modeled as a whole the fault zone cannot support a high CO 2 column. We adapted oil-field methods to calculate column heights and sealing capacities. Examination of the burial and tectonic histories of the rocks, coupled with field- and micro-­scale studies, allow us to examine the potential for seal failure using basic rock mechanics failure analyses. These studies reveal that the sealing lithologies experienced multiple episodes of deformation that resulted in numerous fractures and small faults. In a stress state based on burial history and overburden loads, we show that most of the seals could fail with normal to slightly excess pore pressures.

58 GEOSCIENCES↗
DOE OSTI2019

Thermoanaerosceptrum fracticalcis gen. nov. sp. nov., a Novel Fumarate-Fermenting Microorganism From a Deep Fractured Carbonate Aquifer of the US Great Basin

Deep fractured rock ecosystems across most of North America have not been studied extensively. However, the US Great Basin, in particular the Nevada National Security Site (NNSS, formerly the Nevada Test Site), has hosted a number of influential subsurface investigations over the years. This investigation focuses on resident microbiota recovered from a hydrogeologically confined aquifer in fractured Paleozoic carbonate rocks at 863 – 923 meters below land surface. Analysis of the microorganisms living in this oligotrophic environment provides a perspective into microbial metabolic strategies required to endure prolonged hydrogeological isolation deep underground. Here we present a microbiological and physicochemical characterization of a deep continental carbonate ecosystem and describe a bacterial genus isolated from the ecosystem. Strain DRI-13 T is a strictly anaerobic, moderately thermophilic, fumarate-respiring member of the phylum Firmicutes . This bacterium grows optimally at 55°C and pH 8.0, can tolerate a concentration of 100 mM NaCl, and appears to obligately metabolize fumarate to acetate and succinate. Culture-independent 16S rRNA gene sequencing indicates a global subsurface distribution, while the closest cultured relatives of DRI-13 T are Pelotomaculum thermopropionicum (90.0% similarity) and Desulfotomaculum gibsoniae (88.0% similarity). The predominant fatty acid profile is iso-C 15:0 , C 15:0 , C 16:0 and C 14:0 . The percentage of the straight-chain fatty acid C 15:0 is a defining characteristic not present in the other closely related species. The genome is estimated to be 3,649,665 bp, composed of 87.3% coding regions with an overall average of 45.1% G + C content. Strain DRI-13 T represents a novel genus of subsurface bacterium isolated from a previously uncharacterized rock-hosted geothermal habitat. The characterization of the bacterium combined with the sequenced genome provides insights into metabolism strategies of the deep subsurface biosphere. Based on our characterization analysis we propose the name Thermoanaerosceptrum fracticalcis (DRI-13 T = DSM 100382 T = ATCC TSD-12 T ).

16S rRNA↗
DOE OSTI2018

Microbial Interactions With Dissolved Organic Matter Drive Carbon Dynamics and Community Succession

Knowledge of dynamic interactions between natural organic matter (NOM) and microbial communities is critical not only to delineate the routes of NOM degradation/transformation and carbon (C) fluxes, but also to understand microbial community evolution and succession in ecosystems. Yet, these processes in subsurface environments are usually studied independently, and a comprehensive view has been elusive thus far. In this study, we fed sediment-derived dissolved organic matter (DOM) to groundwater microbes and continually analyzed microbial transformation of DOM over a 50-day incubation. To document fine-scale changes in DOM chemistry, we applied high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and soft X-ray absorption spectroscopy (sXAS). We also monitored the trajectory of microbial biomass, community structure and activity over this time period. Together, these analyses provided an unprecedented comprehensive view of interactions between sediment-derived DOM and indigenous subsurface groundwater microbes. Microbial decomposition of labile C in DOM was immediately evident from biomass increase and total organic carbon (TOC) decrease. The change of microbial composition was closely related to DOM turnover: microbial community in early stages of incubation was influenced by relatively labile tannin- and protein-like compounds; while in later stages the community composition evolved to be most correlated with less labile lipid- and lignin-like compounds. These changes in microbial community structure and function, coupled with the contribution of microbial products to DOM pool affected the further transformation of DOM, culminating in stark changes to DOM composition over time. Our study demonstrates a distinct response of microbial communities to biotransformation of DOM, which improves our understanding of coupled interactions between sediment-derived DOM, microbial processes, and community structure in subsurface groundwater.

59 BASIC BIOLOGICAL SCIENCES↗