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948 records · Page 53Linked to original sources
USGS2020

Applications of correlative light and electron microscopy (CLEM) to organic matter in the North American shale petroleum systems

Scanning electron microscopy (SEM) has revolutionized our understanding of shale petroleum systems through microstructural characterization of dispersed organic matter (OM). However, due to the low atomic weight of carbon, all OM appears black in SEM (BSE image) regardless of differences in thermal maturity or OM type (kerogen types or solid bitumen). Traditional petrographic identification of OM uses optical microscopy, where reflectance (%Ro), form, relief and fluorescence can be used to discern OM types and thermal maturation stage. Unfortunately, most SEM studies of shale OM do not employ correlative optical techniques, leading to misidentifications or to the conclusion that all OM (i.e., kerogen and solid bitumen) is the same. To improve the accuracy of SEM identifications of dispersed OM in shale, this study used correlative light and electron microscopy (CLEM) to create optical and SEM images of OM in the same fields of view (500x magnification) under white light, blue light, secondary electron, and backscatter electron conditions. Samples (n=8) of varying thermal maturities and typical of the North American shale petroleum systems were used, including the Green River Mahogany Zone, Bakken Formation, Ohio Shale, Eagle Ford Formation, Barnett Formation, Haynesville Formation and Woodford Shale. The CLEM image sets demonstrate the importance of correlative microscopy by showing how easily OM can be misidentified when viewed by SEM alone. Without CLEM techniques, petrographic data from SEM such as observations of organic nano-porosity may be misinterpreted, resulting in false or ambiguous results and impairing an improved understanding of organic diagenesis and catagenesis.

Book chapter↗
USGS2020

Micrometer-scale characterization of solid mine waste aids in closure due diligence

Precious- and base-metal mining often occurs in deposits with high acid-generating potential, resulting in mine waste that contains metals in forms of varying bioavailability, and therefore toxicity. The solids that host these metals are often noncrystalline, nanometer to micrometer in size, or undetectable by readily available analytical techniques (e.g., X-ray diffraction). This analytical shortcoming can pose a challenge when attempting to characterize sources and natural attenuation of metals at a given site, which is a best practice to satisfy closure due diligence. Numerous case studies have shown that efforts to characterize mine waste at multiple scales, particularly the micrometer scale, often lead to a better understanding of metal distribution and potential contamination risks. This paper presents a case study that compares the use of both traditional and non-traditional techniques to identify and quantify metal hosts in sediments downstream of the abandoned mine waste piles at the Ely Copper Mine Superfund site in Vermont (USA). The contaminant present in the highest concentration in the sediments is copper, yet not all copper-bearing solids were detected with bulk X-ray diffraction (XRD). At the micrometer scale, a combination of synchrotron-based X-ray absorption spectroscopy (XAS) and an automated mineralogy (AM) system were used to identify the most abundant copper-bearing solids. Bulk XAS and AM also provided semi-quantitative abundances of these solids in the sediment. At the Ely Copper Mine, copper in stream sediments was found to be predominantly hosted in sulphide minerals downstream of a major mine waste pile, whereas upstream copper was predominantly hosted in secondary iron and manganese (oxyhydr)oxides. These copper-bearing hosts were consistent with the expected bioavailability of copper in the sediments based on laboratory toxicity tests with aquatic organisms. When the bulk of copper was present in sulphides, aquatic organisms experienced greater survival than when copper was mostly associated with secondary iron and manganese (oxyhydr)oxides. The information gained from probing the sediments at multiple scales can now be used to prioritize containment and remediation strategies. While synchrotron-based analytical techniques have proven to be invaluable in many studies of mine waste, access to these techniques is limited. In contrast, access to a scanning electron microscope that can perform AM is becoming more common, primarily for the application in mining design and mineral processing operations. More recently, the successful use of AM to characterize mine waste suggests that this technique can be equally as valuable for mine closure plans. The resolution of information obtained may go beyond what is required from a regulatory perspective, but given that the results have the potential to be more conclusive than many traditional techniques, this level of characterization may save time and money in the long run.

Vermont↗
USGS1981

Survey for bright Mars-crossing asteroids

A new method of search for relatively bright Mars-crossing asteroids with the Palomar 46-cm Schmidt camera was initiated in 1980. Selected fields photographed with the 46-cm Schmidt were systematically reduced for all asteroids detected on the films. The 46-cm Schmidt fields have an effective diameter of 8 3/4 degrees. Kodak 11a-D film was exposed with a yellow plexiglass filter. The films were scanned with a specially designed stereomicroscope that permits recognition of asteroids by stereopsis. Stereoscopic pairs of films were exposed with a time separation of 30 minutes; over this interval the parallax in position relative to the background stars allows easy recognition of asteroids at distances ranging from near the Earth through the main belt. Optimum exposure for each film was found to be 10 minutes on the f/2 Schmidt.

Book chapter↗
USGS1977

Heat capacities of gibbsite, Al(OH)3, between 13 and 480 K and magnesite, MgCO3, between 13 and 380 K and their standard entropies at 289.15 K, and the heat capacities of Calorimetry Conference benzoic acid between 12 and 316 K

The heat capacities of gibbsite and magnesite were measured between 13 and 380 K by means of an adiabatic calorimeter. The heat capacity of gibbsite was measured continuously between 340 and 480 K by means of a differential scanning calorimeter. Tables of the thermodynamic functions C° P , (H° T –H° O )/T ,– (G° T –H° O )/T , and S° T –S° O are presented for these phases at integral temperatures. S° T –S° O are 68.44±0.14 J/(K•mol) and 65.09±0.13 J/(K•mol) at 298.15 K for gibbsite and magnesite, respectively. The heat capacities of Calorimetry Conference benzoic acid have been remeasured between 12 and 316 K.

Journal of Research of the U.S. Geological Survey↗
USGS2024

Nonbreeding waterfowl behavioral response to crewed and uncrewed aerial surveys on conservation areas in Missouri

Monitoring waterfowl populations provides the basis for improving habitat quantity and quality, establishing harvest regulations, and ensuring sustainable waterfowl populations through appropriate management. Waterfowl biologists currently use a variety of population and habitat monitoring methods ranging from informal ground observations to low-level occupied aircraft surveys. Although unoccupied aerial systems (UAS) may provide safer and more precise alternatives to traditional aerial survey techniques that are less disturbing to waterfowl, there is limited information on how waterfowl in winter respond to UAS. We compared the behavioral responses of waterfowl to helicopters and UAS on Missouri Department of Conservation wetland conservation areas October – February 2021-2022. Helicopter surveys were flown using an Airbus H125 helicopter at heights of 100 – 350 m, with UAS surveys flown using a DJI Mavic 2 Pro UAS at 15 – 90 m. Waterfowl behavior was categorized as alert, swim, fly, or abandonment using flock-scan surveys recorded for 10-minute periods before, during, and after the surveys. The percentage of time flocks spent in each behavior during- or post-survey were compared to time spent in those behaviors pre-survey. Waterfowl increased time spent swimming, flying, and abandonment in response to helicopter flights, whereas UAS flights did not influence overall waterfowl behavior. Additionally, waterfowl did not change behavior in response to UAS flights regardless of waterfowl guild (mallard, other duck, or goose) or hunting season (open or closed). Waterfowl did increase flight behavior during UAS flights at 30 m, however, there was no change in behavior at all other UAS survey altitudes. UAS may be a good alternative to traditional waterfowl survey methods and are not likely to affect waterfowl distributions or energy expenditures during the survey periods.

Missouri↗
USGS2025

Predation of Lost River and Shortnose Suckers by piscivorous colonial waterbirds in the Upper Klamath Basin: An analysis of predation effects in 2024

The recovery of endangered fish requires an understanding of the sources of mortality that regulate population dynamics. We estimated avian predation rates on passive integrated transponder tagged (PIT) adult and juvenile Lost River Suckers ( Deltistes luxatus ), Shortnose Suckers ( Chasmistes brevirostris ), Klamath Largescale Suckers ( C. snyderi ), and juvenile Chinook Salmon ( Oncorhynchus tshawytscha ) by breeding colonies of American White Pelicans ( Pelecanus erythrorhynchos ), Doublecrested Cormorants ( Nannopterum auritum ), Caspian Terns ( Hydroprogne caspia ), California Gulls ( Larus californicus ), Ring-billed Gulls ( L. delawarensis ), Great Blue Herons ( Ardea herodias ), Great Egrets ( A. alba ), and Black-crowned Night Herons ( Nycticorax nycticorax ) in the Upper Klamath Basin (UKB) in 2024. Results from 2024 contribute to a long-term (2009–2023) avian predation dataset in the UKB. The largest numbers of pelicans (1,422 breeding adults), terns (610 adults), and gulls (3,872) were nesting on islands in Clear Lake Reservoir. The largest number of cormorants (787 adults) were on an island in Sheepy Lake, and the largest numbers of herons (450 adults) were at arboreal sites adjacent to Upper Klamath Lake. Predation rate estimates in 2024 were highly variable depending on the fish species, ageclass (juvenile, adult), waterbody (Upper Klamath Lake, Clear Lake Reservoir, Sheepy Lake, Tule Lake), and release or reencounter date for juveniles (spring/summer or fall/winter). Results indicated that avian predation rates were the highest on wild and hatchery juvenile suckers. An estimated 19.4% (95% credible interval = 15.7–24.0) of Sucker Assisted Rearing Program (SARP) hatchery fish, released or reencountered during the spring and summer, were consumed by the colonies included in the study. Predation was also appreciable on wild juvenile suckers in Clear Lake Reservoir (13.4% [9.9–17.7]) and SARP juvenile suckers released or reencountered in Upper Klamath Lake in the fall/winter (11.2% [9.6 13.2]). Predation rate estimates on adult suckers were significantly lower than those of juvenile suckers, with predation ranging from 0.3% (0.2–0.7) to 2.6% (1.9–3.5) in adult Lost River Suckers in Upper Klamath Lake and adult Shortnose Suckers-Klamath Largescale Suckers in Clear Lake Reservoir, respectively. Predation rate estimates on juvenile Chinook Salmon, which were released in fall/winter, were 2.9% (2.2–3.6). Pelican (312 adults) and cormorant (301 adults) colonies in Upper Klamath Lake, however, were not scanned for fish PIT tags following breeding season, resulting in minimum estimates of predation on UKB fishes (both suckers and Chinook Salmon) in 2024. Future research could examine what biotic and abiotic factors best explain variation in predation and to what degree predation limits sucker survival using the long-term dataset that has been complied to date.

California, Oregon↗
USGS1995

Find the fish: using PROC SQL to build a relational database

Reliable estimates of abundance and survival, gained through mark-recapture studies, are necessary to better understand how to manage and restore lake trout populations in the Great Lakes. Working with a 24-year data set from a mark-recapture study conducted in Lake Superior, we attempted to disclose information on tag shedding by examining recaptures of double-tagged fish. The data set consisted of 64,288 observations on fish which had been marked with one or more tags; a subset of these fish had been marked with two tags at initial capture. Although DATA and PROC statements could be used to obtain some of the information we sought, these statements could not be used to extract a complete set of results from the double-tagging experiments. We therefore used SQL processing to create three tables representing the same information but in a fully normalized relational structure. In addition, we created indices to efficiently examine complex relationships among the individual capture records. This approach allowed us to obtain all the information necessary to estimate tag retention through subsequent modeling. We believe that our success with SQL was due in large part to its ability to simultaneosly scan the same table more than once and to permit consideration of other tables in sub-queries.

Book chapter↗
USGS1987

PROTON MICROPROBE ANALYSIS OF TRACE-ELEMENT VARIATIONS IN VITRINITES IN THE SAME AND DIFFERENT COAL BEDS.

The PIXE (proton-induced X-ray emission) microprobe can be used for nondestructive, in-situ analyses of areas as small as those analyzed by the electron microprobe, and has a sensitivity of detection as much as two orders of magnitude better than the electron microprobe. Preliminary studies demonstrated that PIXE provides a capability for quantitative determination of elemental concentrations in individual coal maceral grains with a detection limit of 1-10 ppm for most elements analyzed. Encouraged by the earlier results, we carried out the analyses reported below to examine trace element variations laterally (over a km range) as well as vertically (cm to m) in the I and J coal beds in the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale in central Utah, and to compare the data with the data from two samples of eastern coals of Pennsylvanian age.

Scanning Micros↗