Oil and natural gas development in the Bakken shale play of North Dakota has grown substantially since 2008. This study provides a comprehensive overview and analysis of water quantity and management ...impacts from this development by (1) estimating water demand for hydraulic fracturing in the Bakken from 2008 to 2012; (2) compiling volume estimates for maintenance water, or brine dilution water; (3) calculating water intensities normalized by the amount of oil produced, or estimated ultimate recovery (EUR); (4) estimating domestic water demand associated with the large oil services population; (5) analyzing the change in wastewater volumes from 2005 to 2012; and (6) examining existing water sources used to meet demand. Water use for hydraulic fracturing in the North Dakota Bakken grew 5-fold from 770 million gallons in 2008 to 4.3 billion gallons in 2012. First-year wastewater volumes grew in parallel, from an annual average of 1 135 000 gallons per well in 2008 to 2 905 000 gallons in 2012, exceeding the mean volume of water used in hydraulic fracturing and surpassing typical 4-year wastewater totals for the Barnett, Denver, and Marcellus basins. Surprisingly, domestic water demand from the temporary oilfield services population in the region may be comparable to the regional water demand from hydraulic fracturing activities. Existing groundwater resources are inadequate to meet the demand for hydraulic fracturing, but there appear to be adequate surface water resources, provided that access is available.
Chemical analyses of three Martian soil samples were performed using the Wet Chemistry Laboratories on the 2007 Phoenix Mars Scout Lander. One soil sample was obtained from the top ∼2 cm (Rosy Red) ...and two were obtained at ∼5 cm depth from the ice table interface (Sorceress 1 and Sorceress 2). When mixed with water in a ∼1:25 soil to solution ratio (by volume), a portion of the soil components solvated. Ion concentrations were measured using an array of ion selective electrodes and solution conductivity using a conductivity cell. The measured concentrations represent the minimum leachable ions in the soil and do not take into account species remaining in the soil. Described is the data processing and analysis for determining concentrations of seven ionic species directly measured in the soil/solution mixture. There were no significant differences in concentrations, pH, or conductivity, between the three samples. Using laboratory experiments, refinement of the surface calibrations, and modeling, we have determined a pH for the soil solution of 7.7(±0.3), under prevalent conditions, carbonate buffering, and PCO2 in the cell headspace. Perchlorate was the dominant anion in solution with a concentration for Rosy Red of 2.7(±1) mM. Equilibrium modeling indicates that measured Ca2+ at 0.56(±0.5) mM and Mg2+ at 2.9(±1.5) mM, are consistent with carbonate equilibrium for a saturated solution. The Na+ and K+ were 1.4(±0.6), and 0.36(±0.3) mM, respectively. Results indicate that the leached portion of soils at the Phoenix landing site are slightly alkaline and dominated by carbonate and perchlorate. However, it should be noted that there is a 5–15 mM discrepancy between measured ions and conductivity and another species may be present.
Detection of Silica-Rich Deposits on Mars Squyres, S.W; Arvidson, R.E; Ruff, S ...
Science (American Association for the Advancement of Science),
05/2008, Volume:
320, Issue:
5879
Journal Article
Peer reviewed
Mineral deposits on the martian surface can elucidate ancient environmental conditions on the planet. Opaline silica deposits (as much as 91 weight percent SiO₂) have been found in association with ...volcanic materials by the Mars rover Spirit. The deposits are present both as light-toned soils and as bedrock. We interpret these materials to have formed under hydrothermal conditions and therefore to be strong indicators of a former aqueous environment. This discovery is important for understanding the past habitability of Mars because hydrothermal environments on Earth support thriving microbial ecosystems.
The Mars rover Opportunity has explored Victoria crater, a approximately 750-meter eroded impact crater formed in sulfate-rich sedimentary rocks. Impact-related stratigraphy is preserved in the ...crater walls, and meteoritic debris is present near the crater rim. The size of hematite-rich concretions decreases up-section, documenting variation in the intensity of groundwater processes. Layering in the crater walls preserves evidence of ancient wind-blown dunes. Compositional variations with depth mimic those approximately 6 kilometers to the north and demonstrate that water-induced alteration at Meridiani Planum was regional in scope.
The Origins, Spectral-Interpretation, Resource-Identification, Security and Regolith-Explorer (OSIRIS-REx) spacecraft supports all aspects of the mission science objectives, from extensive remote ...sensing at the asteroid Bennu, to sample collection and return to Earth. In general, the success of planetary missions requires the collection, return, and analysis of data, which in turn depends on the successful operation of instruments and the host spacecraft. In the case of OSIRIS-REx, a sample-return mission, the spacecraft must also support the acquisition, safe stowage, and return of the sample. The target asteroid is Bennu, a B-class near-Earth asteroid roughly 500 m diameter. The Lockheed Martin-designed and developed OSIRIS-REx spacecraft draws significant heritage from previous missions and features the Touch-and-Go-Sample-Acquisition-Mechanism, or TAGSAM, to collect sample from the surface of Bennu. Lockheed Martin developed TAGSAM as a novel, simple way to collect samples on planetary bodies. During short contact with the asteroid surface, TAGSAM releases curation-grade nitrogen gas, mobilizing the surface regolith into a collection chamber. The contact surface of TAGSAM includes “contact pads”, which are present to collect surface grains that have been subject to space weathering. Extensive 1-g laboratory testing, “reduced-gravity” testing (via parabolic flights on an airplane), and analysis demonstrate that TAGSAM will collect asteroid material in nominal conditions, and a variety of off-nominal conditions, such as the presence of large obstacles under the TAGSAM sampling head, or failure in the sampling gas firing. TAGSAM, and the spacecraft support of the instruments, are central to the success of the mission.
The alpha particle x-ray spectrometer on the Spirit rover determined major and minor elements of soils and rocks in Gusev crater in order to unravel the crustal evolution of planet Mars. The ...composition of soils is similar to those at previous landing sites, as a result of global mixing and distribution by dust storms. Rocks (fresh surfaces exposed by the rock abrasion tool) resemble volcanic rocks of primitive basaltic composition with low intrinsic potassium contents. High abundance of bromine (up to 170 parts per million) in rocks may indicate the alteration of surfaces formed during a past period of aqueous activity in Gusev crater.
The chemical composition of rocks and soils on Mars analyzed during the Mars Exploration Rover Spirit Mission was determined by X‐ray analyses with the Alpha Particle X‐Ray Spectrometer (APXS). ...Details of the data analysis method and the instrument calibration are presented. Measurements performed on Mars to address geometry effects and background contributions are shown. Cross calibration measurements among several instrument sensors and sources are discussed. An unintentional swap of the two flight instruments is evaluated. New concentration data acquired during the first 470 sols of rover Spirit in Gusev Crater are presented. There are two geological regions, the Gusev plains and the Columbia Hills. The plains contain soils that are very similar to previous landing sites on Mars. A meteoritic component in the soil is identified. Rocks in the plains revealed thin weathering rinds. The underlying abraded rock was classified as primitive basalt. One of these rocks contained significant Br that is probably associated with vein‐filling material of different composition. One of the trenches showed large subsurface enrichments of Mg, S, and Br. Disturbed soils and rocks in the Columbia Hills revealed different elemental compositions. These rocks are significantly weathered and enriched in mobile elements, such as P, S, Cl, or Br. Even abraded rock surfaces have high Br concentrations. Thus, in contrast to the rocks and soils in the Gusev Plains, the Columbia Hills material shows more significant evidence of ancient aqueous alteration.
Outcrop exposures of sedimentary rocks at the Opportunity landing site (Meridiani Planum) form a set of genetically related strata defined here informally as the Burns formation. This formation can ...be subdivided into lower, middle, and upper units which, respectively, represent eolian dune, eolian sand sheet, and mixed eolian sand sheet and interdune facies associations. Collectively, these three units are at least 7 m thick and define a “wetting-upward” succession which records a progressive increase in the influence of groundwater and, ultimately, surface water in controlling primary depositional processes.
The Burns lower unit is interpreted as a dry dune field (though grain composition indicates an evaporitic source), whose preserved record of large-scale cross-bedded sandstones indicates either superimposed bedforms of variable size or reactivation of lee-side slip faces by episodic (possibly seasonal) changes in wind direction. The boundary between the lower and middle units is a significant eolian deflation surface. This surface is interpreted to record eolian erosion down to the capillary fringe of the water table, where increased resistance to wind-induced erosion was promoted by increased sediment cohesiveness in the capillary fringe. The overlying Burns middle unit is characterized by fine-scale planar-laminated to low-angle-stratified sandstones. These sandstones accumulated during lateral migration of eolian impact ripples over the flat to gently undulating sand sheet surface. In terrestrial settings, sand sheets may form an intermediate environment between dune fields and interdune or playa surfaces. The contact between the middle and upper units of the Burns formation is interpreted as a diagenetic front, where recrystallization in the phreatic or capillary zones may have occurred. The upper unit of the Burns formation contains a mixture of sand sheet facies and interdune facies. Interdune facies include wavy bedding, irregular lamination with convolute bedding and possible small tepee or salt-ridge structures, and cm-scale festoon cross-lamination indicative of shallow subaqueous flows marked by current velocities of a few tens of cm/s. Most likely, these currents were gravity-driven, possibly unchannelized flows resulting from the flooding of interdune/playa surfaces. However, evidence for lacustrine sedimentation, including mudstones or in situ bottom-growth evaporites, has not been observed so far at Eagle and Endurance craters.
Mineralogical and elemental data indicate that the eolian sandstones of the lower and middle units, as well as the subaqueous and eolian deposits of the Burns upper unit, were derived from an evaporitic source. This indirectly points to a temporally equivalent playa where lacustrine evaporites or ground-water-generated efflorescent crusts were deflated to provide a source of sand-sized particles that were entrained to form eolian dunes and sand sheets. This process is responsible for the development of sulfate eolianites at White Sands, New Mexico, and could have provided a prolific flux of sulfate sediment at Meridiani. Though evidence for surface water in the Burns formation is mostly limited to the upper unit, the associated sulfate eolianites provide strong evidence for the critical role of groundwater in controlling sediment production and stratigraphic architecture throughout the formation.
Confirming abstinence during smoking cessation clinical trials is critical for determining treatment effectiveness. Several biological methods exist for verifying abstinence (e.g., exhaled carbon ...monoxide CO, cotinine), and while cotinine provides a longer window of detection, it is not easily used in trials involving nicotine replacement therapy. The Society for Research on Nicotine and Tobacco's Subcommittee on Biochemical Verification cite 8-10 parts per million (ppm) for CO as a viable cutoff to determine abstinence; however, recent literature suggests this cutoff is likely too high and may overestimate the efficacy of treatment.
This study examined the relationship between CO and cotinine in a sample of 662 individuals participating in a smoking cessation clinical trial. A receiver operating characteristics curve was calculated to determine the percentage of false positives and false negatives at given CO levels when using cotinine as confirmation of abstinence. Differences were also examined across race and gender.
A CO cutoff of 3 ppm (97.1% correct classification) most accurately distinguished smokers from nonsmokers. This same cutoff was accurate for both racial and gender groups. The standard cutoffs of 8 ppm (14.0% misclassification of smokers as abstainers) and 10 ppm (20.6% misclassification of smokers as abstainers) produced very high false-negative rates and inaccurately identified a large part of the sample as being abstinent when their cotinine test identified them as still smoking.
It is recommended that researchers and clinicians adopt a more stringent CO cutoff in the range of 3-4 ppm when complete abstinence from smoking is the goal.
The interactions between electrons and lattice vibrations are fundamental to materials behaviour. In the case of group IV-VI, V and related materials, these interactions are strong, and the materials ...exist near electronic and structural phase transitions. The prototypical example is PbTe whose incipient ferroelectric behaviour has been recently associated with large phonon anharmonicity and thermoelectricity. Here we show that it is primarily electron-phonon coupling involving electron states near the band edges that leads to the ferroelectric instability in PbTe. Using a combination of nonequilibrium lattice dynamics measurements and first principles calculations, we find that photoexcitation reduces the Peierls-like electronic instability and reinforces the paraelectric state. This weakens the long-range forces along the cubic direction tied to resonant bonding and low lattice thermal conductivity. Our results demonstrate how free-electron-laser-based ultrafast X-ray scattering can be utilized to shed light on the microscopic mechanisms that determine materials properties.
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