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At least 145 records · Page 8Linked to original sources
USGS2014

Thermal-maturity limit for primary thermogenic-gas generation from humic coals as determined by hydrous pyrolysis

Hydrous-pyrolysis experiments at 360°C (680°F) for 72 h were conducted on 53 humic coals representing ranks from lignite through anthracite to determine the upper maturity limit for hydrocarbon-gas generation from their kerogen and associated bitumen (i.e., primary gas generation). These experimental conditions are below those needed for oil cracking to ensure that generated gas was not derived from the decomposition of expelled oil generated from some of the coals (i.e., secondary gas generation). Experimental results showed that generation of hydrocarbon gas ends before a vitrinite reflectance of 2.0%. This reflectance is equivalent to Rock-Eval maximum-yield temperature and hydrogen indices (HIs) of 555°C (1031°F) and 35 mg/g total organic carbon (TOC), respectively. At these maturity levels, essentially no soluble bitumen is present in the coals before or after hydrous pyrolysis. The equivalent kerogen atomic H/C ratio is 0.50 at the primary gas-generation limit and indicates that no alkyl moieties are remaining to source hydrocarbon gases. The convergence of atomic H/C ratios of type-II and -I kerogen to this same value at a reflectance of indicates that the primary gas-generation limits for humic coal and type-III kerogen also apply to oil-prone kerogen. Although gas generation from source rocks does not exceed vitrinite reflectance values greater than , trapped hydrocarbon gases can remain stable at higher reflectance values. Distinguishing trapped gas from generated gas in hydrous-pyrolysis experiments is readily determined by of the hydrocarbon gases when a -depleted water is used in the experiments. Water serves as a source of hydrogen in hydrous pyrolysis and, as a result, the use of -depleted water is reflected in the generated gases but not pre-existing trapped gases.

AAPG Bulletin↗
USGS2018

Understanding and distinguishing reflectance measurements of solid bitumen and vitrinite using hydrous pyrolysis: Implications to petroleum assessment

Solid bitumen is a common organic component of thermally mature shales and typically is identified by embayment against euhedral mineral terminations and by groundmass textures. However, because these textures are not always present, solid bitumen can be easily misidentified as vitrinite. Hydrous-pyrolysis experiments (72 hr, 300°C–360°C) on shale and coal samples show that solid-bitumen reflectance ( BR o ) in shales is less responsive to thermal stress than vitrinite reflectance ( R o ) in coal. This effect is most pronounced at lower experimental temperatures (300°C–320°C), whereas reflectance changes are more similar at higher temperatures (340°C–360°C). Neither a “vitrinite-like” maceral nor “suppressed vitrinite” was identified or measured in our sample set; instead, the experiments show that solid bitumen matures slower than vitrinite. The data may explain some reports of “ R o suppression,” particularly at lower thermal maturity ( R o ≤ 1.0%), as a simple case of solid bitumen being mistaken for vitrinite. Further, the experimental results confirm previous empirical observations that R o and BR o are more similar at higher maturities ( R o > 1.0%). It is suggested that R o suppression, commonly reported from upper Paleozoic marine shales of early to midoil window maturity, is a misnomer. This observation has important implications to petroleum exploration models and resource assessment, because it may change interpretations for the timing and spatial locations of kerogen maturation and petroleum generation.

AAPG Bulletin↗
USGS2021

Incorporation of uncertainty to improve projections of tidal wetland elevation and carbon accumulation with sea-level rise

Understanding the rates and patterns of tidal wetland elevation changes relative to sea-level is essential for understanding the extent of potential wetland loss over the coming years. Using an enhanced and more flexible modeling framework of an ecosystem model (WARMER-2), we explored sea-level rise (SLR) impacts on wetland elevations and carbon sequestration rates through 2100 by considering plant community transitions, salinity effects on productivity, and changes in sediment availability. We incorporated local experimental results for plant productivity relative to inundation and salinity into a species transition model, as well as site-level estimates of organic matter decomposition. The revised modeling framework includes an improved calibration scheme that more accurately reconstructs soil profiles and incorporates parameter uncertainty through Monte Carlo simulations. Using WARMER-2, we evaluated elevation change in three tidal wetlands in the San Francisco Bay Estuary, CA, USA along an estuarine tidal and salinity gradient with varying scenarios of SLR, salinization, and changes in sediment availability. We also tested the sensitivity of marsh elevation and carbon accumulation rates to different plant productivity functions. Wetland elevation at all three sites was sensitive to changes in sediment availability, but sites with greater initial elevations or space for upland transgression persisted longer under higher SLR rates than sites at lower elevations. Using a multi-species wetland vegetation transition model for organic matter contribution to accretion, WARMER-2 projected increased elevations relative to sea levels (resilience) and higher rates of carbon accumulation when compared with projections assuming no future change in vegetation with SLR. A threshold analysis revealed that all three wetland sites were likely to eventually transition to an unvegetated state with SLR rates above 7 mm/yr. Our results show the utility in incorporating additional estuary-specific parameters to bolster confidence in model projections. The new WARMER-2 modeling framework is widely applicable to other tidal wetland ecosystems and can assist in teasing apart important drivers of wetland elevation change under SLR.

California↗
USGS2022

Assembling a safe and effective toolbox for integrated flea control and plague mitigation: Fipronil experiments with prairie dogs

Background Plague, a widely distributed zoonotic disease of mammalian hosts and flea vectors, poses a significant risk to ecosystems throughout much of Earth. Conservation biologists use insecticides for flea control and plague mitigation. Here, we evaluate the use of an insecticide grain bait, laced with 0.005% fipronil (FIP) by weight, with black-tailed prairie dogs (BTPDs, Cynomys ludovicianus ). We consider safety measures, flea control, BTPD body condition, BTPD survival, efficacy of plague mitigation, and the speed of FIP grain application vs. infusing BTPD burrows with insecticide dusts. We also explore conservation implications for endangered black-footed ferrets ( Mustela nigripes ), which are specialized predators of Cynomys . Principal findings During 5- and 10-day laboratory trials in Colorado, USA, 2016–2017, FIP grain had no detectable acute toxic effect on 20 BTPDs that readily consumed the grain. During field experiments in South Dakota, USA, 2016–2020, FIP grain suppressed fleas on BTPDs for at least 12 months and up to 24 months in many cases; short-term flea control on a few sites was poor for unknown reasons. In an area of South Dakota where plague circulation appeared low or absent, FIP grain had no detectable effect, positive or negative, on BTPD survival. Experimental results suggest FIP grain may have improved BTPD body condition (mass:foot) and reproduction (juveniles:adults). During a 2019 plague epizootic in Colorado, BTPDs on 238 ha habitat were protected by FIP grain, whereas BTPDs were nearly eliminated on non-treated habitat. Applications of FIP grain were 2–4 times faster than dusting BTPD burrows. Significance Deltamethrin dust is the most commonly used insecticide for plague mitigation on Cynomys colonies. Fleas on BTPD colonies exhibit the ability to evolve resistance to deltamethrin after repeated annual treatments. Thus, more tools are needed. Accumulating data show orally-delivered FIP is safe and usually effective for flea control with BTPDs, though potential acute toxic effects cannot be ruled out. With continued study and refinement, FIP might be used in rotation with, or even replace deltamethrin, and serve an important role in Cynomys and black-footed ferret conservation. More broadly, our stepwise approach to research on FIP may function as a template or guide for evaluations of insecticides in the context of wildlife conservation.

South Dakota↗
USGS2014

Tritium and deuterium content of atmospheric hydrogen

The tritium and deuterium content of 24 samples of atmospheric hydrogen collected at ground level near Buffalo. N.Y. (U.S.A.). Hamburg (Germany), and Nürnberg (Germany) during 1954 to 1956 was measured. At the beginning of 1954 the T/H-ratio was found to have been 9.18 · 10 -14 i.e. about a factor of 10 higher than 1949 (FALTINGS and HARTECK) and 1951 (v. GROSSE et al.), probably due to the first explosion of a thermonuclear device in November 1952. In spite of a major test series of thermonuclear weapons in spring of 1954 (Operation CASTLE) no further increase in the tritium content was found during 1954 and 1955. It shows instead a seasonal variation with low tritium content in summer and about a threefold higher one in winter. Simultaneously, there is a good correlation between the tritium and deuterium concentrations. From 1956 on a noticeable increase in the tritium content due to more man-made HT produced or released by thermonuclear devices into the atmosphere was found, in agreement with measurements by GONSIOR. A possible explanation of the experimental results as well as a mode to test the validity of the model suggested is given. The deuterium concentrations of the samples analysed vary between about +7 percent and –17 percent, compared to Standard Lake Michigan Water with a ratio D/H = 0.0148 ± 0.0002 mol percent. Although from these results only a correlation factor between the tritium and deuterium content of “mean atmospheric hydrogen” and not their absolute values can be derived it is obvious that atmospheric hydrogen and the water vapour of the atmosphere are not in thermodynamic equilibrium, as has been pointed out before by HARTECK and SUESS.

Zeitschrift fur Naturforschung A↗
USGS2000

Growth and food consumption by tiger muskellunge: Effects of temperature and ration level on bioenergetic model predictions

We measured growth of age-0 tiger muskellunge as a function of ration size (25, 50, 75, and 100% C max ) and water temperature (7.5–25°C) and compared experimental results with those predicted from a bioenergetic model. Discrepancies between actual and predicted values varied appreciably with water temperature and growth rate. On average, model output overestimated winter consumption rates at 10 and 7.5°C by 113 to 328%, respectively, whereas model predictions in summer and autumn (20–25°C) were in better agreement with actual values (4 to 58%). We postulate that variation in model performance was related to seasonal changes in esocid metabolic rate, which were not accounted for in the bioenergetic model. Moreover, accuracy of model output varied with feeding and growth rate of tiger muskellunge. The model performed poorly for fish fed low rations compared with estimates based on fish fed ad libitum rations and was attributed, in part, to the influence of growth rate on the accuracy of bioenergetic predictions. Based on modeling simulations, we found that errors associated with bioenergetic parameters had more influence on model output when growth rate was low, which is consistent with our observations. In addition, reduced conversion efficiency at high ration levels may contribute to variable model performance, thereby implying that waste losses should be modeled as a function of ration size for esocids. Our findings support earlier field tests of the esocid bioenergetic model and indicate that food consumption is generally overestimated by the model, particularly in winter months and for fish exhibiting low feeding and growth rates.

Transactions of the American Fisheries Society↗
USGS2010

Salinity tolerance of the African Jewelfish Hemichromis letourneuxi , a non-native cichlid in South Florida (USA)

The African Jewelfish (Cichlidae: Hemichromis letourneuxi ) is a predatory, non-native fish that has recently (since 2000) begun to expand its geographic range across south Florida. The salinity tolerance of H. letourneuxi was unknown, and thus it was unclear whether the species could use estuarine or coastal environments. The response of H. letourneuxi to chronic change in salinity was evaluated here by exposing fish to progressively increasing salinities (0–80 ppt). Fish were held at target salinities for a minimum of 30 days. The species showed excellent survival from 0–50 ppt. At 60 ppt, only 25% of the fish survived, and mean estimated survival time was 12 days. Above 60 ppt, mortality was 100%. Fish grew equally well from 0–50 ppt. In another experiment, fish were transferred directly from freshwater to various salinities from 5–35 ppt (seawater) and held for seven days, after which survivors were returned to freshwater. All fish transferred directly from freshwater to salinities up to 20 ppt survived; only 56% survived when transferred from freshwater to 25 ppt, and none survived transfer above 25 ppt. Experimental results indicated that H. letourneuxi can persist easily in salinities prevalent in coastal environments, even during periods of hypersalinity common in south Florida estuaries. Salinity will not restrict its dispersal by coastal pathways.

Florida↗
USGS2017

Effects of thermal variability on broadband seismometers: Controlled experiments, observations, and implications

Isolating seismic instruments from temperature fluctuations is routine practice within the seismological community. However, the necessary degree of thermal stability required in broadband installations to avoid generating noise or compromising the fidelity in the seismic records is largely unknown and likely application dependent. To quantify the temperature sensitivity of seismometers over a broad range of frequencies, we artificially induced local temperature changes on three different models of seismometers to measure the effect of thermal variations on seismometer output. We found that diurnal temperature changes above 0.002°C root mean square (rms) showed significant changes in velocity and acceleration output in comparison to thermally stable reference measurements. We also found that sensor incoherent self‐noise increased with temperature variation; these increases in noise can be modeled as 1 / f "> 1 / f noise (pink noise), and are unlikely to be easily corrected for. These experimental results are compared with the data from Incorporated Research Institutions for Seismology (IRIS) U.S. Geological Survey (USGS) Global Seismographic Network (GSN) station TUC (Tucson, Arizona). This station is well instrumented with temperature sensors and has three different broadband seismometers, each of which uses a different method of thermal isolation. We show that the water bricks and borehole installations give ample temperature attenuation to thermally isolate seismometers from diurnal thermal variability that would compromise seismic data. We find that seismometer installations that provide thermal stability below 0.002°C rms could help to improve long‐period vertical seismic data across the GSN by decreasing temperature‐driven 1 / f "> 1 / f noise.

Bulletin of the Seismological Society of America↗
USGS2026

Measuring stress In high pressure deformation experiments with high speed fiber-optics

High‐pressure, high‐temperature rock deformation experiments are essential for understanding deep Earth processes, but accurately measuring stress is challenging due to the inaccuracy introduced by seal friction within the apparatus and large inertia, which affects earthquake process measurements made far from the experimental fault. To overcome these limitations, we developed and implemented a simple, compact fiber‐optic sensor based on an External Cavity Fabry–Perot Interferometer for in situ load measurement on a piston inside the pressure vessel of a Griggs‐type high‐pressure apparatus. The sensor can be used at sample temperatures up to 800°C for both slow creep and fast rupture testing with bandwidth capability from DC to 6 MHz. Two important experimental results are described: (1) the first direct measurements of seal friction in this apparatus type; these measurements record seal friction approximately one‐tenth of the confining pressure under both low (150 MPa) and high (1 GPa) pressure conditions; and (2) high‐temporal resolution capture of dynamic stress drops during stick‐slip faulting events at high‐confining pressure, revealing near‐fault wave propagation details, high‐frequency oscillations, and implying high‐transient slip rates (6–12 m/s) previously inaccessible with external sensors.

The Seismic Record↗
USGS2006

Effects of stream enclosures on drifting invertebrates and fish growth

Stream ecologists often use enclosure experiments to investigate predator-prey interactions and competition within and among fish species. The design of enclosures, manipulation of species densities, and method of replication may influence experimental results. We designed an experiment with enclosure cages (1 m2, 6-mm mesh) to examine the relative influence of fish size, density, and prey availability on growth of brown trout (Salmo trutta), brook trout (Salvelinus fontinalis), and slimy sculpin (Cottus cognatus) within enclosures in Valley Creek, Minnesota. In addition, we examined water flow and invertebrate drift entering enclosures and in open riffles to investigate whether enclosures reduced the supply of invertebrate prey. Growth of small (age-0) brook and brown trout was not influenced by fish density, but growth of larger (age-1) trout generally decreased as density increased. Sculpin growth was not related to fish size or density, but increased with mean size of invertebrates in the drift. Enclosures reduced water flow and tended to reduce invertebrate drift rate, although total drift rate (ind./min), total drift density (ind./m3), and mean size of invertebrates were not significantly different inside enclosures compared to adjacent stream riffles. Enclosures had no effect on drift rate or size of Gammarus pseudolimnaeus, the main prey item for trout and sculpin in Valley Creek. Overall, our analyses indicated that reductions of prey availability by enclosures did not influence fish growth. Trout growth may have been limited at larger sizes and densities because of increased activity costs of establishing and defending territories, whereas sculpin growth was related to availability of large prey, a factor not influenced by enclosures. ?? 2006 by The North American Benthological Society.

Journal of the North American Benthological Societ↗
USGS2005

Gold enrichment and the Bi-Au association in pyrrhotite-rich massive sulfide deposits, Escanaba trough, Southern Gorda Ridge

High gold contents (to 10.1 ppm, avg 1.4 ppm, n = 34) occur in pyrrhotite-rich massive sulfide samples from the sediment-covered floor of the Escanaba trough, the slow-spreading, southernmost segment of Gorda Ridge. These concentrations reflect the presence of primary gold, formed during high-temperature hydrothermal activity in mounds and chimneys, and secondary gold deposited during sea-floor weathering of massive sulfide. Primary gold occurs as fine-grained (<2 ??m) gold, electrum, maldonite (Au2Bi), and a rare unnamed mineral (AuBi5S4) and is texturally and temporally associated with sulfarsenides (arsenopyrite, glaucodot, alloclastite, and cobaltite), arsenides (lo??llingite and safflorite), Bi minerals (native bismuth, Bi tellurides, Bi-Te sulfides, and bismuthinite), and galena. Larger (>2 ??m) secondary gold grains have a porous, flaky morphology and occur in samples in which pyrrhotite is oxidized and replaced by Fe oxyhydroxides, Fe sulfate, and sulfur. Mounds and chimneys dominated by pyrrhotite and containing lesser amounts of isocubanite, chalcopyrite, and Fe-rich sphalerite were formed by high-temperature (estimated range 325??-275??C), reduced, low-sulfur vent fluids. The mineral and fluid compositions during this main stage of hydrothermal venting reflect subsurface interaction between circulating hydrothermal fluids and turbiditic sediment containing as much as 1.1 percent organic carbon. As the deposition of pyrrhotite, Cu-Fe sulfides, and sphalerite waned, a volumetrically minor suite of sulfarsenide, arsenide, Bi, and Au minerals was deposited from highly reduced, late main-stage fluids diffusing through mounds and chimneys. The low solubility of Au as a bisulfide complex and the absence of fluid mixing during this stage of hydrothermal activity apparently inhibited the precipitation of gold directly from solution. Instead, gold precipitation is thought to be linked to elevated concentrations of Bi in the late main-stage fluids. The textural relationships of Au and Bi minerals in pyrrhotite-rich samples, low melting point of native bismuth (271.4??C), and recent experimental results on Au and Bi in hydrothermal fluids contribute to the hypothesis that gold was effectively scavenged from the Escanaba trough vent fluids by coexisting droplets of liquid bismuth. Additional phase relationships of alloys in the Au-Bi system indicate that deposition of native bismuth and maldonite occurred at temperatures as low as 241??C. Bismuth droplets trapped in void space between main-stage mineral grains scavenged gold from ambient hydrothermal fluid to a greater extent than bismuth enclosed by late-forming pyrrhotite. The limited solid solution of Au in Bi can explain the apparent exsolution texture in which gold blebs are hosted by native bismuth. The electrum, native bismuth (with gold inclusions), and galena represent the last traces of gold mineralization from late main-stage fluids. During sea-floor weathering and the oxidation of pyrrhotite in the mounds and chimneys, secondary gold formed as aggregates of colloidal particles along pH gradients between acidic pore waters and ambient seawater. Gold was mobilized from earlier formed primary gold minerals and transported as aqueous chloride complexes. The reduction of Au(III) by residual Fe2+ in partly altered pyrrhotite and adsorption of colloids by Fe oxyhydroxides may have influenced the location of secondary gold grains within the alteration front. Solubility differences between gold and silver chloride complexes at low temperature account for the low Ag content of secondary gold grains. The high concentrations of Bi, and thus the association of Au and Bi minerals in pyrrhotite-rich massive sulfide, can be ascribed to the extensive interaction of hydrothermal fluids with sediment in the Escanaba trough. In contrast, the absence of the Au-Bi association in massive sulfides at other ridges, including other sediment-covered sites at Middle Valley and the Guaymas basin

Economic Geology↗
USGS1965

Electrochemical geothermometer: A possible new method of geothermometry with electro-conductive minerals

It was demonstrated with artificially processed sulfides that the minimum temperature of equilibration of a pair of electro - conductive minerals can be determined electrochemically. The procedure consists of setting up an electrochemical cell with the mineral electrodes and a suitable electrolyte, changing the temperature of the cell slowly in a furnace, and finding the temperature at which the emf of the cell becomes zero. The experimental results strongly suggest that this electrochemical method could be used as a new method of geothermometry .

Economic Geology↗
USGS1967

The Fe-Pb-S system

The phase relations in the ternary system Fe - Pb - S were determined by quenching and differential thermal analysis experiments in rigid silica-glass tubes. The solubilities of FeS in galena and in liquid Pb and the extent of solid solution of PbS in pyrite and pyrrhotite at 700° C are too small to be determined by the methods employed and are probably less than 0.1 wt. percent. Less than 1 wt. percent S is soluble in liquid Pb at 700° C. Ternary compounds do not occur in this system . An invariant point involving galena, pyrite, sulfide liquid, liquid sulfur, and vapor occurs at 716° C. The ternary liquid at this temperature contains about 60 wt. percent Pb , 13 wt. percent Fe , and 27 wt. percent S , and is thus situated slightly on the sulfur side of the PbS-FeS2 join. At 719° C tie lines between galena and pyrite are replaced by sulfide liquid-pyrrhotite tie lines in an invariant reaction involving vapor. The sulfide liquid field expands rapidly and intersects the PbS-FeS2 join at 723° C. At 848° C the ternary liquid field intersects the FeS-PbS join. Diagrams are presented to illustrate changes in phase relations from 700° to 1,115° C. The experimental results demonstrate that mixtures of galena (about 70 wt. percent) and pyrite (about 30 wt. percent) can crystallize directly from a liquid at 716° C. Additional components may lower this temperature so that it appears possible that pyrite-galena ores may melt at temperatures below 700° C when exposed to thermal metamorphism.

Economic Geology↗
USGS2014

Assessment of the geoavailability of trace elements from selected zinc minerals

This assessment focused on five zinc-bearing minerals. The minerals were subjected to a number of analyses including quantitative X-ray diffraction, optical microscopy, leaching tests, and bioaccessibility and toxicity studies. Like a previous comprehensive assessment of five copper-bearing minerals, the purpose of this assessment was to obtain structural and chemical information and to characterize the reactivity of each mineral to various simulated environmental and biological conditions. As in the copper minerals study, analyses were conducted consistent with widely accepted methods. Unless otherwise noted, analytical methods used for this study were identical to those described in the investigation of copper-bearing minerals. Two sphalerite specimens were included in the zinc-minerals set. One sphalerite was recovered from a mine in Balmat, New York; the second came from a mine in Creede, Colorado. The location and conditions of origin are significant because, as analyses confirmed, the two sphalerite specimens are quite different. For example, data acquired from a simulated gastric fluid (SGF) study indicate that the hydrothermally formed Creede sphalerite contains orders of magnitude higher arsenic, cadmium, manganese, and lead than the much older metamorphic Balmat sphalerite. The SGF and other experimental results contained in this report suggest that crystallizing conditions such as temperature, pressure, fluidization, or alteration processes significantly affect mineral properties—properties that, in turn, influence reactivity, solubility, and toxicity. The three remaining minerals analyzed for this report—smithsonite, hemimorphite, and hydrozincite—are all secondary minerals or alteration products of zinc-ore deposits. In addition, all share physical characteristics such as tenacity, density, streak, and cleavage. Similarities end there. The chemical composition, unit-cell parameters, acid-neutralizing potential, and other observable and quantifiable properties indicate very different minerals. Only one of each of these minerals was studied. Had this assessment included multiples of these minerals, geochemical and mineralogical distinctions would have emerged, similar to the results for the two sphalerite specimens.

Arizona;Chihuahua;Colorado;New York↗
USGS1962

Study of natural glasses through their behavior as membrane electrodes, Part 2

The exchange constants and regular solution constants for a number of exchange reactions involving analyzed natural and simulated natural glasses have been determined. The experimental method used provides quick and simple determination of these constants. The calculation of the internal energy differences of model ion exchange systems involving alkali and alkaline earth cations yields sequences (but not magnitudes) of selectivity that agree with the experimental results. Complex glasses such as obsidians, tektites and basaltic glasses do not in general show simple correlations between composition and ion exchange behavior.

Open-File Report↗
USGS1982

Thermodynamic properties of selected uranium compounds and aqueous species at 298.15 K and 1 bar and at higher temperatures; preliminary models for the origin of coffinite deposits

Thermodynamic values for 110 uranium-bearing phases and 28 aqueous uranium solution species (298.15 K and l bar) are tabulated based upon evaluated experimental data (largely from calorimetric experiments) and estimated values. Molar volume data are given for most of the solid phases. Thermodynamic values for 16 uranium-bearing phases are presented for higher temperatures in the form of and as a supplement to U.S. Geological Survey Bulletin 1452 (Robie et al., 1979). The internal consistency of the thermodynamic values reported herein is dependent upon the reliability of the experimental results for several uranium phases that have been used as secondary calorimetric reference phases. The data for the reference phases and for those phases evaluated with respect to the secondary reference phases are discussed. A preliminary model for coffinite formation has been proposed together with an estimate of the free energy of formation of coffinite. Free energy values are estimated for several other uranium-bearing silicate phases that have been reported as secondary uranium phases associated with uranium ore deposits and that could be expected to develop wherever uranium is leached by groundwaters.

Open-File Report↗
USGS2025

Climate change impacts on plant communities in the sagebrush region—A science synthesis to inform Bureau of Land Management resource management

This report synthesizes current (2024) science-based knowledge related to the impacts of climate change on big sagebrush vegetation in Western North America. This effort was conducted through the U.S. Geological Survey working with the Bureau of Land Management as part of multiple science syntheses to aid management agencies developing environmental impacts assessments in response to human-related or caused events. This report reviews the potential impacts climate change may have on sagebrush vegetation and related management decisions. The body of the synthesis introduces the diverse impacts of climate change across the region by first focusing directly on what climate change may entail in terms of altered temperature and precipitation patterns. The report then discusses how these changes could likely affect individual plant species based on experimental results and scale the impacts to species distributions and community composition. The synthesis section ends by surveying efforts to model potential future changes in habitat. The report goes on to link the synthesis conclusions to individual land uses or land management decisions, such as forage resources, restoration or fuel treatment. Finally, the report provides a section that discusses the pros and cons of available datasets that model the potential future of vegetation in the sagebrush region.

Arizona, California, Colorado, Idaho, Montana, Nev↗
USGS2025

MIMAR-Net: Multiscale Inception-based Manhattan Attention Residual Network and its application to underwater image super-resolution

In recent years, Single-Image Super-Resolution (SISR) has gained significant attention in the geoscience and remote sensing community for its potential to improve the resolution of low-quality underwater imagery. This paper introduces MIMAR-Net ( M ultiscale I nception-based M anhattan A ttention R esidual Network), a new deep learning architecture designed to increase the spatial resolution of input color images. MIMAR-Net integrates a multiscale inception module, cascaded residue learning, and advanced attention mechanisms, such as the MaSA layer, to capture both local and global contextual information effectively. By utilizing multiscale processing and advanced attention strategies, MIMAR-Net allows us to handle the complexities of underwater environments with precision and robustness. We evaluate the model on three popular underwater image datasets, namely UFO-120, USR-248, and EUVP, and perform extensive comparisons against state-of-the-art methods. Experimental results demonstrate that MIMAR-Net consistently outperforms existing approaches, achieving superior qualitative and quantitative improvements in image quality, making it a reliable solution for underwater image enhancement in various challenging scenarios.

Electronics↗