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At least 595 records · Page 33Linked to original sources

USGS2006

The HRSC DTM test

The High Resolution Stereo Camera (HRSC) has been orbiting the planet Mars since January 2004 onboard the ESA Mars Express mission and delivers imagery which is being used for topographic mapping of the planet. The HRSC team is currently conducting a systematic inter-comparison of different alternatives for the production of high resolution Digital Terrain Models (DTMs) from the multilook HRSC push broom imagery. Based on carefully chosen test sites the test participants have produced DTMs which have been subsequently analysed in a quantitative and a qualitative manner. This paper reports on the results obtained in this test.

Conference Paper↗

USGS2019

Viable long-term gas hydrate testing site confirmed on the Alaska north slope

In December 2018, data acquired in a Stratigraphic Test Well drilled from the 7-11-12 pad in the western part of the Prudhoe Bay Unit, Alaska North Slope confirmed the occurrence of two high-quality reservoirs fully saturated with gas hydrate. The drilling was the initial phase of a planned, three-well program designed to conduct an extended duration test of the response to gas hydrate reservoirs to controlled depressurization. The Stratigraphic Test Well (formally “PBU Hydrate-01”) was operated by the PBU Operator BP Exploration, (Alaska), Inc. (BPXA) using the Parker 272 drilling rig (Figure 1) through a Drilling Services Agreement executed with Petrotechnical Resources of Alaska (PRA) in association with a contract between NETL and PRA. The science program executed by BPXA was developed over a two-year period through extensive discussions and scientific evaluation undertaken by NETL, the Japan, Oil, Gas, and Metals, National Corporation (JOGMEC), the U.S. Geological Survey (USGS), and PRA. The effort also benefitted greatly from the support of the Alaska Department of Natural Resources (ADNR) and the PBU Working Interest Owners (WIOs).

Alaska↗

USGS2020

Alaska North Slope 2018 Hydrate-01 Stratigraphic Test Well: Technical results

The Hydrate-01 Stratigraphic Test Well was drilled in December 2018 to confirm that a seismically-identified location within the western Prudhoe Bay Unit might be suitable for extended-duration scientific production testing. The well tested two primary targets: the deeper Unit B is highly favorable due to optimal reservoir temperature and minimal observed risk for direct communication with permeable, hydrate-free water-bearing zones. The shallower Unit D provides a secondary target and opportunity to assess additional scientific and operational issues.

Alaska↗

USGS2023

Field testing of an underwater acoustic deterrent system in a Marseilles pool gravel pit on the Illinois River

Acoustic deterrent technologies are being developed to prevent the spread of invasive carp (Bighead Carp, Silver Carp, Grass Carp, and Black Carp) from the Mississippi River watershed to the Great Lakes. To assess this technology, field testing of the deterrent equipment and newly developed sound stimuli on wild invasive carp populations is essential. Large-scale experimental deployments and testing of UADS are currently installed or proposed at multiple locks and dams. However, there has been limited use or testing of underwater acoustic deterrents in smaller areas where lock infrastructure does not exist (e.g., side channels and backwaters). These more natural areas have important characteristics that differ from hard-structured locks and dams, such as soft substrate, flashy flow conditions, shallow or variable water depth, and inconsistent bathymetry/bottom elevation.

Illinois↗

USGS1970

Testing of selected pharmacological agents for capturing waterfowl [Annual Progress Report]

The response of game-farm mallards (Frost strain) to seven pharmacological immobilizing agents was evaluated in Phase I of a planned four-phase study. A limited amount of testing was also done with wild mallards. Single dosages were administered to determine the mean effective dose (ED50) and mean lethal dose (LD50), The therapeutic index, or safety factor (LD50/ED50), and palatability were also established. Optimum dosage rates of compounds administered orally on baits were not considered in this phase of the study. Compounds were-administered by intubation and calculated in terms of mg/kg. All except one compound produced narcosis within 5 minutes at the effective dose rate.Immobilization periods for the seven compounds ranged from 7-24 minutes, and recovery periods from 1.0-6.5 hours. Such wide variations in actions of the compounds can be attributed to a compound's rate of absorption, the ease with which it passes the blood-brain barrier, its solubility in tissues, and its rate of metabolism in the liver and kidneys. Length of both the immobilization and recovery periods were extended when dosages were increased. There was no delayed mortality among survivors with any of the seven compounds at either the ED50 or LD50. Females were generally more sensitive to the anesthetizing agents than males. The ED50 for wild mallards was substantially higher than that for the experimental game-farm birds for the two compounds on which this was tested.Tribromoethanol (Avertin of Winthrop Laboratories) satisfied all test criteria an Phase I and will be subjected to more intensive investigation in ensuing tests. Thiopental sodium (Pentothal of Amdal Company) and pentobarbital sodium (Nembutal of Abbott Laboratories) were judged to be marginal. Although their therapeutic indexes were good (5.00), recovery periods were prolonged and toxic convulsions occurred at medium to high dose rates as the LD50 was approached.Alpha-chloralose (Fisher Scientific) proved least promising of the seven compounds, mainly because of its unacceptable therapeutic index (2.25) and because it possesses prolonged induction and recovery periods. Two new experimental drugs, methoxymol and metomidate (Pitman-Moore), appeared effective and safe when administered by intubation but produced a taste aversion when added to bait. Rejection because of taste was also a problem with secobarbital (Seconal of Elanco Products), and its therapeutic index of 2.75 was unacceptable. Monitoring of heart and respiratory rates, and body temperature by telemetry showed promise as a technique for determining physiological response to drug action.

Report↗

USGS1998

Theoretical Evaluation of the Transient Response of Constant Head and Constant Flow-Rate Permeability Tests

A theoretical analysis is presented that compares the response characteristics of the constant head and the constant flowrate (flow pump) laboratory techniques for quantifying the hydraulic properties of geologic materials having permeabilities less than 10-10 m/s. Rigorous analytical solutions that describe the transient distributions of hydraulic gradient within a specimen are developed, and equations are derived for each method. Expressions simulating the inflow and outflow rates across the specimen boundaries during a constant-head permeability test are also presented. These solutions illustrate the advantages and disadvantages of each method, including insights into measurement accuracy and the validity of using Darcy's law under certain conditions. The resulting observations offer practical considerations in the selection of an appropriate laboratory test method for the reliable measurement of permeability in low-permeability geologic materials.

Geotechnical Testing Journal↗

USGS2016

Testing fault growth models with low-temperature thermochronology in the northwest Basin and Range, USA

Common fault growth models diverge in predicting how faults accumulate displacement and lengthen through time. A paucity of field-based data documenting the lateral component of fault growth hinders our ability to test these models and fully understand how natural fault systems evolve. Here we outline a framework for using apatite (U-Th)/He thermochronology (AHe) to quantify the along-strike growth of faults. To test our framework, we first use a transect in the normal fault-bounded Jackson Mountains in the Nevada Basin and Range Province, then apply the new framework to the adjacent Pine Forest Range. We combine new and existing cross sections with 18 new and 16 existing AHe cooling ages to determine the spatiotemporal variability in footwall exhumation and evaluate models for fault growth. Three age-elevation transects in the Pine Forest Range show that rapid exhumation began along the range-front fault between approximately 15 and 11 Ma at rates of 0.2–0.4 km/Myr, ultimately exhuming approximately 1.5–5 km. The ages of rapid exhumation identified at each transect lie within data uncertainty, indicating concomitant onset of faulting along strike. We show that even in the case of growth by fault-segment linkage, the fault would achieve its modern length within 3–4 Myr of onset. Comparison with the Jackson Mountains highlights the inadequacies of spatially limited sampling. A constant fault-length growth model is the best explanation for our thermochronology results. We advocate that low-temperature thermochronology can be further utilized to better understand and quantify fault growth with broader implications for seismic hazard assessments and the coevolution of faulting and topography.

Tectonics↗

USGS2024

Testing food web theory in a large lake: The role of body size in habitat coupling in Lake Michigan

The landscape theory of food web architecture (LTFWA) describes relationships among body size, trophic position, mobility, and energy channels that serve to couple heterogenous habitats, which in turn promotes long-term system stability. However, empirical tests of the LTFWA are rare and support differs among terrestrial, freshwater, and marine systems. Further, it is unclear whether the theory applies in highly altered ecosystems dominated by introduced species such as the Laurentian Great Lakes. Here, we provide an empirical test of the LTFWA by relating body size, trophic position, and the coupling of different energy channels using stable isotope data from species throughout the Lake Michigan food web. We found that body size was positively related to trophic position, but for a given trophic position, organisms predominately supported by pelagic energy had smaller body sizes than organisms predominately supported by nearshore benthic energy. We also found a hump-shaped trophic relationship in the food web where there is a gradual increase in the coupling of pelagic and nearshore energy channels with larger body sizes as well as higher trophic positions. This highlights the important role of body size and connectivity among habitats in structuring food webs. However, important deviations from expectations are suggestive of how species introductions and other anthropogenic impacts can affect food web structure in large lakes. First, native top predators appear to be flexible couplers that may provide food web resilience, whereas introduced top predators may confer less stability when they specialize on a single energy pathway. Second, some smaller bodied prey fish and invertebrates, in addition to mobile predators, coupled energy from pelagic and nearshore energy channels, which suggests that some prey species may also be important integrators of energy pathways in the system. We conclude that patterns predicted by the LTFWA are present in the face of species introductions and other anthropogenic stressors to a degree, but time-series evaluations are needed to fully understand the mechanisms that promote stability.

Lake Michigan↗

USGS2015

In Response: Biological arguments for selecting effect sizes in ecotoxicological testing—A governmental perspective

Criticisms of the uses of the no-observed-effect concentration (NOEC) and the lowest-observed-effect concentration (LOEC) and more generally the entire null hypothesis statistical testing scheme are hardly new or unique to the field of ecotoxicology [ 1-4 ]. Among the criticisms of NOECs and LOECs is that statistically similar LOECs (in terms of p value) can represent drastically different levels of effect. For instance, my colleagues and I found that a battery of chronic toxicity tests with different species and endpoints yielded LOECs with minimum detectable differences ranging from 3% to 48% reductions from controls [ 5 ].

Environmental Toxicology and Chemistry↗

USGS1994

Community‐level field method for testing the toxicity of contaminated sediments in estuaries

The objective of this study was to demonstrate a method for testing the toxicity of contaminated sediments under field conditions. An artificial sediment that matches field sediment in grain‐size distribution and organic matter content was mixed from 11 components and used as the test substrate. Clean sediments and sediments spiked with zinc (∼8,000 mg/kg) were exposed in the field on a holding rack anchored on the bottom of Mobile Bay, Alabama. The abundance and diversity (species richness) of benthic invertebrate recruits were used as indicators of sediment quality. The number of recruits was significantly reduced by the presence of zinc in one‐week exposures.

Environmental Toxicology and Chemistry↗

USGS1996

A test of vegetation-related indicators of wetland quality in the prairie pothole region

This study was part of an effort by the U.S. Environmental Protection Agency to quantitatively assess the environmental quality or 'health' of wetland resources on regional and national scales. During a two-year pilot study, we tested selected indicators of wetland quality in the U.S. portion of the prairie pothole region (PPR). We assumed that the amount of cropland versus non-cropland (mostly grassland) in the plots containing these basins was a proxy for their quality. We then tested indicators by their ability to discriminate between wetlands at the extremes of that proxy. Amounts of standing dead vegetation were greater in zones of greater water permanence. Depth of litter was greater in zones of greater water permanence and in zones of basins in poor-quality watersheds. Amounts of unvegetated bottom were greater in basins in poor-quality watersheds; lesser amounts occurred in all wetlands during a wetter year. Greater amounts of open water occurred during a wetter year and in zones of greater water permanence. When unadjusted for areas (ha) of communities, plant taxon richness was higher in wet-meadow and shallow-marsh zones in good-quality watersheds than in similar zones in poor-quality watersheds. Wet-meadow zones in good-quality watersheds had greater numbers of native perennials than those in poor-quality watersheds. This relation held when we eliminated all communities in good-quality watersheds larger than the largest communities in poor-quality watersheds from the data set. We conclude that although amounts of unvegetated bottom and plant taxon richness in wet-meadow zones were useful indicators of wetland quality during our study, the search for additional such indicators should continue. The value of these indicators may change with the notoriously unstable hydrological conditions in the PPR. Most valuable would be indicators that could be photographed or otherwise remotely sensed and would remain relatively stable under various hydrological conditions. An ideal set of indicators could detect the absence of stressors, as well as the presence of structures or functions, of known value to major groups of organisms.

Journal of Aquatic Ecosystem Health↗

USGS1988

Habitat islands and the equilibrium theory of island biogeography: testing some predictions

Species-area data from a study of marsh birds are used to test five predictions generated by the equilibrium theory of island biogeography. Three predictions are supported: we found a significant species-area relationship, a non-zero level of turnover, and a variance-mean ratio of 0.5. One prediction is rejected: the extinction rates were not greater on small islands. The results of one test are equivocal: the number of species on each island was not always the same. As Gilbert (1980) suggests, a strong species-area relationship alone does not validate the theory. The avian communities we studied were on habitat islands, not true islands, and underwent complete extinction annually. Thus caution must be used before applying the theory to these and other habitat islands.

Oecologia↗

USGS1996

Estimating aquatic toxicity as determined through laboratory tests of great lakes sediments containing complex mixtures of environmental contaminants

We developed and evaluated a total toxic units modeling approach for predicting mean toxicity as measured in laboratory tests for Great Lakes sediments containing complex mixtures of environmental contaminants (e.g., polychlorinated biphenyls, polycyclic aromatic hydrocarbons, pesticides, chlorinated dioxins, and metals). The approach incorporates equilibrium partitioning and organic carbon control of bioavailability for organic contaminants and acid volatile sulfide (AVS) control for metals, and includes toxic equivalency for planar organic chemicals. A toxic unit is defined as the ratio of the estimated pore-water concentration of a contaminant to the chronic toxicity of that contaminant, as estimated by U.S. Environmental Protection Agency Ambient Water Quality Criteria (AWQC). The toxic unit models we developed assume complete additivity of contaminant effects, are completely mechanistic in form, and were evaluated without any a posteriori modification of either the models or the data from which the models were developed and against which they were tested. A linear relationship between total toxic units, which included toxicity attributable to both iron and un-ionized ammonia, accounted for about 88% of observed variability in mean toxicity; a quadratic relationship accounted for almost 94%. Exclusion of either bioavailability components (i.e., equilibrium partitioning control of organic contaminants and AVS control of metals) or iron from the model substantially decreased its ability to predict mean toxicity. A model based solely on un-ionized ammonia accounted for about 47% of the variability in mean toxicity. We found the toxic unit approach to be a viable method for assessing and ranking the relative potential toxicity of contaminated sediments.

Great Lakes region↗

USGS1973

Tests of pesticidal synergism with young pheasants and Japanese quail

Thirteen pairs of chemicals involving 18 pesticides and two polychlorinated biphenyl preparations were each fed for 5 days to Japanese quail or ring-necked pheasant chicks 7 to 16 days of age. Malathion + EPN, and malathion + trichlorofon were moderately synergistic in tests with both species, whereas joint toxicities of the other chemicals tended to be additive. Comparisons with other studies of joint action of pesticides against mammals and insects suggest that the two species of birds tested are less susceptible to synergism than are mammals or insects. The results also suggest that the likelihood of a factor of synergism greater than three in birds is not great.

Bulletin of Environmental Contamination and Toxico↗

USGS1977

Examination of the Chayes-Kruskal procedure for testing correlations between proportions

The Chayes-Kruskal procedure for testing correlations between proportions uses a linear approximation to the actual closure transformation to provide a null value, pij, against which an observed closed correlation coefficient, rij, can be tested. It has been suggested that a significant difference between pij and rij would indicate a nonzero covariance relationship between the ith and jth open variables. In this paper, the linear approximation to the closure transformation is described in terms of a matrix equation. Examination of the solution set of this equation shows that estimation of, or even the identification of, significant nonzero open correlations is essentially impossible even if the number of variables and the sample size are large. The method of solving the matrix equation is described in the appendix. ?? 1977 Plenum Publishing Corporation.

Mathematical Geology↗

USGS2001

An interlaboratory study to test instrument performance of hydrogen dual-inlet isotope-ratio mass spectrometers

An interlaboratory comparison of forty isotope-ratio mass spectrometers of different ages from several vendors has been performed to test 2 H/ 1 H performance with hydrogen gases of three different isotopic compositions. The isotope-ratio results (unsufficiently corrected for H 3 + contribution to the m/z = 3 collector, uncorrected for valve leakage in the change-over valves, etc.) expressed relative to one of these three gases covered a wide range of values: –630‰ to –790‰ for the second gas and –368‰ to –462‰ for the third gas. After normalizing the isotopic abundances of these test gases (linearly adjusting the δ values so that the gases with the lowest and highest 2 H content were identical for all laboratories), the standard deviation of the 40 measurements of the intermediate gas was a remarkably low 0.85‰. It is concluded that the use of scaling factors is mandatory for providing accurate internationally comparable isotope-abundance values. Linear scaling for the isotope-ratio scales of gaseous hydrogen mass spectrometers is completely adequate.

Fresenius' Journal of Analytical Chemistry↗

USGS2005

A test of geographic assignment using isotope tracers in feathers of known origin

We used feathers of known origin collected from across the breeding range of a migratory shorebird to test the use of isotope tracers for assigning breeding origins. We analyzed δD, δ 13 C, and δ 15 N in feathers from 75 mountain plover ( Charadrius montanus ) chicks sampled in 2001 and from 119 chicks sampled in 2002. We estimated parameters for continuous-response inverse regression models and for discrete-response Bayesian probability models from data for each year independently. We evaluated model predictions with both the training data and by using the alternate year as an independent test dataset. Our results provide weak support for modeling latitude and isotope values as monotonic functions of one another, especially when data are pooled over known sources of variation such as sample year or location. We were unable to make even qualitative statements, such as north versus south, about the likely origin of birds using both δD and δ 13 C in inverse regression models; results were no better than random assignment. Probability models provided better results and a more natural framework for the problem. Correct assignment rates were highest when considering all three isotopes in the probability framework, but the use of even a single isotope was better than random assignment. The method appears relatively robust to temporal effects and is most sensitive to the isotope discrimination gradients over which samples are taken. We offer that the problem of using isotope tracers to infer geographic origin is best framed as one of assignment, rather than prediction.

Oecologia↗

USGS2005

Contact zone permeability at intrusion boundaries: New results from hydraulic testing and geophysical logging in the Newark Rift Basin, New York, USA

Hydraulic tests and geophysical logging performed in the Palisades sill and the underlying sedimentary rocks in the NE part of the Newark Rift Basin, New York, USA, confirm that the particular transmissive zones are localized within the dolerite-sedimentary rock contact zone and within a narrow interval below this contact zone that is characterized by the occurrence of small layers of chilled dolerite. Transmissivity values determined from fluid injection, aquifer testing, and flowmeter measurements generally fall in the range of 8.1E-08 to 9.95E-06 m 2 /s and correspond to various scales of investigation. The analysis of acoustic and optical BHTV images reveals two primary fracture sets within the dolerite and the sedimentary rocks—subhorizontal fractures, intersected by subvertical ones. Despite being highly fractured either with subhorizontal, subvertical or both fracture populations, the dolerite above and the sedimentary rocks below the contact zone and the zone with the layers of chilled dolerite are significantly less conductive. The distribution of the particular conductive intervals is not a function of the two dominant fracture populations or their density but rather of the intrusion path of the sill. The intrusion caused thermal fracturing and cracking of both formations, resulting in higher permeability along the contact zone.

Hydrogeology Journal↗