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At least 109 records · Page 6Linked to original sources
USGS2002

Porometric properties of siliciclastic marine sand: A comparison of traditional laboratory measurements with image analysis and effective medium modeling

During the 1999 sediment acoustics experiment (SAX99), porometric properties were measured and predicted for a well sorted, medium sand using standard laboratory geotechnical methods and image analysis of resin-impregnated sediments. Sediment porosity measured by laboratory water-weight-loss methods (0.372 ?? 0.0073 for mean ??1 standard deviation) is 0.026 lower than determined by microscopic image analysis of resin-impregnated sediments (0.398 ?? 0.029). Values of intrinsic permeability (m2) determined from constant-head permeameter measurements (3.29 ?? 10-11 ?? 0.60 ?? 10-11) and by microscopic image analysis coupled with effective medium theory modeling (2.78 ?? 10-11 ?? 1.01 ?? 10-11) are nearly identical within measurement error. The mean value of tortuosity factor measured from images is 1.49 ?? 0.09, which is in agreement with tortuosity factor determined from electrical resistivity measurements. Slight heterogeneity and anisotropy are apparent in the top three centimeters of sediment as determined by image-based porometric property measurements. However, the overall similarity for both measured and predicted values of porosity and permeability among and within SAX99 sites indicates sediments are primarily homogeneous and isotropic and pore size distributions are fairly uniform. The results indicate that an effective medium theory technique and two-dimensional image analysis accurately predicts bulk permeability in resin-impregnated sands.

IEEE Journal of Oceanic Engineering↗
USGS2022

Comparison of microscopy and metabarcoding to identify pollen used by the critically endangered rusty patched bumble bee, Bombus affinis

Taxonomic analysis of pollen collected by bees can provide insights into their host plant use, providing information about the plant species selected for targeted conservation strategies. The two main identification approaches used are morphological analysis of pollen samples affixed to microscope slides (i.e., microscopic palynology) and molecular analysis of samples. Both methods are widely used for freshly collected materials and have been compared in multiple studies, yet their application to archived samples remains to be explored. Archived samples may be particularly useful for the study of rare or protected species, particularly when historical foraging patterns are uncertain. We used both methods to analyse pollen collected by the endangered rusty patched bumble bee species, Bombus affinis Cresson, applied to museum-archived specimens. Pollen samples were removed from the corbiculae of bumble bees originally collected in Michigan between 1914 and 1974. Samples included 24 rusty patched bumble bees each with large pollen loads on both corbiculae, allowing for pollen from the same bee to be analysed using both methods. DNA metabarcoding detected more plant taxa than light microscopy, and DNA barcoding also had higher taxonomic resolution when compared to taxa determined using light microscopy. In many instances, pollen could only be confidently identified to tribe or family with light microscopy. Discrepancy between methods decreased when taxa identified via DNA metabarcoding were binned into ecologically relevant groups corresponding to those identified using light microscopy. Although binning demonstrated smaller within-method variance, there was still minimal correspondence between the two methods. Results indicate there are benefits and biases unique to each method and highlight the utility of binning taxonomic results to morphological or ecological groupings.

Insect Conservation and Diversity↗
USGS1981

Chrysophyte cysts as potential environmental indicators

Many Chrysophyte algae produce morphologically distinctive, siliceous, microscopic cysts during a resting stage of their life cycles; these cysts are often preserved in sediments. Scanning electron microscopy and Nomarski optics permit much more detailed observation of these cysts than was heretofore possible. We have used an ecologic and biogeographic approach to study the distribution of cyst forms in sediments and have established that many cyst types are found only in specific habitats, such as montane lakes, wet meadows, ephemeral ponds, and Sphagnum bogs. In the samples we have studied, cysts seem to be most common in fluctuating fresh-water habitats of low to moderate pH and some winter freezing. Numerous taxonomic problems have yet to be resolved. We believe that chrysophyte cysts have the potential to become a useful tool for both modern environmental assessments and paleoecological studies of Cenozoic fresh-water lacustrine deposits.

Geological Society of America Bulletin↗
USGS1994

Artifacts resembling budding bacteria produced in placer-gold amalgams by nitric acid leaching

Microscopic filiform morphologies in gold which are indistinguishable from forms originally interpreted as bacterial in origin were produced in the laboratory by treating amalgams made from natural and artificial gold with hot nitric acid. Textures ranging from cobblestone to deeply crenulated to nodular filiform were produced in the laboratory from all tested natural and artificial gold amalgams; analogous textures widespread in Alaskan placer gold may have a similar inorganic origin. These results indicate that morphology alone cannot be considered adequate evidence of microbial involvement in gold formation.

Geology↗
USGS1992

A theoretical model for the flux of radon from rock to ground water

A model is derived to predict the abundance of 222 Rn in ground water in contact with a rock of known uranium content. The model assumes that secular equilibrium is attained in the rock-water system as a whole, but is independent of any microscopic geometric properties of the system. The key variables in the model are bulk properties such as porosity, uranium content of the rock, emanating efficiency, and rock density, all of which are measurable. Thus, the model is simplified by the averaging effects of a macroscopic view of the system. Although less rigorous than other models presented in the literature, it is more generally applicable to natural systems because it does not rely on microscopic properties of the system, which are impossible to quantify. Application of the model to crystalline aquifers in the eastern United States shows that bulk emanation rates of radon are generally less than about 30%.

GSA Special Papers↗
USGS2025

Holding time or fixative formulation has no obvious effect on histology of Porites evermanni and Montipora capitata

Collection of coral for histologic examination requires holding of samples in seawater for a time before they are fixed for histologic processing. This could adversely affect the interpretation of morphologic changes during histologic examinations. We evaluated the microscopic morphology of Porites evermanni and Montipora capitata held (0–120 minutes) in seawater prior to fixation in Z-Fix formulated with raw or artificial seawater. We saw no evident effects of treatments on microscopic morphology. However, among 88 statistical comparisons, and after accounting for false discovery rate, holding time prior to fixation was associated with a significant increase in degree of mucosity of basal body walls.

Veterinary Pathology↗
USGS2018

Characterization of Plasmodium relictum, a cosmopolitan agent of avian malaria

Background Microscopic research has shown that Plasmodium relictum is the most common agent of avian malaria. Recent molecular studies confirmed this conclusion and identified several mtDNA lineages, suggesting the existence of significant intra-species genetic variation or cryptic speciation. Most identified lineages have a broad range of hosts and geographical distribution. Here, a rare new lineage of P. relictum was reported and information about biological characters of different lineages of this pathogen was reviewed, suggesting issues for future research. Methods The new lineage pPHCOL01 was detected in Common chiffchaff Phylloscopus collybita, and the parasite was passaged in domestic canaries Serinus canaria . Organs of infected birds were examined using histology and chromogenic in situ hybridization methods. Culex quinquefasciatus mosquitoes, Zebra finch Taeniopygia guttata, Budgerigar Melopsittacus undulatus and European goldfinch Carduelis carduelis were exposed experimentally. Both Bayesian and Maximum Likelihood analyses identified the same phylogenetic relationships among different, closely-related lineages pSGS1, pGRW4, pGRW11, pLZFUS01, pPHCOL01 of P. relictum. Morphology of their blood stages was compared using fixed and stained blood smears, and biological properties of these parasites were reviewed. Results Common canary and European goldfinch were susceptible to the parasite pPHCOL01, and had markedly variable individual prepatent periods and light transient parasitaemia. Exo-erythrocytic and sporogonic stages were not seen. The Zebra finch and Budgerigar were resistant. Neither blood stages nor vector stages of all examined P. relictum lineages can be distinguished morphologically. Conclusion Within the huge spectrum of vertebrate hosts, mosquito vectors, and ecological conditions, different lineages of P. relictum exhibit indistinguishable, markedly variable morphological forms. Parasites of same lineages often develop differently in different bird species. Even more, the variation of biological properties (parasitaemia dynamics, blood pathology, prepatent period) in different isolates of the same lineage might be greater than the variation in different lineages during development in the same species of birds, indicating negligible taxonomic value of such features. Available lineage information is excellent for parasite diagnostics, but is limited in predictions about relationships in certain host-parasite associations. A combination of experiments, field observations, microscopic and molecular diagnostics is essential for understanding the role of different P. relictum lineages in bird health.

Malaria Journal↗
USGS1982

A rapid method for concentrating sedimentary organic matter for vitrinite reflectance analysis

The tecnique discussed in this paper utilizes crushing, high-speed blending, and ultrasonic treatment to mechanically disaggregate rock and release the sedimentary organic matter (OM) in a suitable heavy liquid. This new method can provide freeze-dried concentrated OM in approximately 8 to 24 hours (longer time is necessary for removing carbonate). Under optimal conditions, it is possible to concentrate the OM and prepare a hardened epoxy microscope slide in about 24 hours. Subsequent grinding, polishing, and drying allows microscopic examination of the organic concentrate the next day.

Journal of Sedimentary Petrology↗
USGS2001

Lack of selection for resistance to whirling disease among progeny of Colorado River rainbow trout

We compared the resistance to whirling disease of two groups of Colorado River rainbow trout Oncorhynchus mykiss and a domestic strain of rainbow trout in a controlled laboratory challenge. These three groups represented the progeny of wild rainbow trout known to have recruited (1) during the early years of infestation by Myxobolus cerebralis of the Colorado River or (2) before the presence of M. cerebralis in the system and (3) the Erwin strain of rainbow trout. The severity of whirling disease in each group was dependent on the dose of triactinomyxons of M. cerebralis to which the fish were exposed. Microscopic lesions and spore counts both increased with increasing parasite dose. Survival of the progeny of Colorado fish that recruited before the presence of M. cerebralis in the system was significantly less than was that of the domestic fish exposed to 0 and 1,000 triactinomyxons/fish. The parents that recruited to the system before the presence of M. cerebralis were considerably older than were those used for our domestic strain; this difference in parent age probably resulted in the difference in survival because egg quality decreases with age in rainbow trout. There was no difference in microscopic lesions, spore counts, or swimming performance among the three groups of rainbow trout when exposed at the same parasite level, indicating that there was no difference in resistance to whirling disease among these groups of fish.

Journal of Aquatic Animal Health↗
USGS1991

A method for the concentration of fine-grained rutile (TiO2) from sediment and sedimentary rocks by chemical leaching

Quaternary marine sediment in the Gulf of Maine basins contains 0.7 to 1.0 wt percent TiO 2 (determined by X-ray fluorescence spectrometry). Most of this TiO 2 exists in the form of silt-size rutile crystals that are visible by using the petrographic microscope with transmitted light (Valentine and Commeau, 1990). The identification of rutile was confirmed by using a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) system. To quantify the amount of TiO 2 in the sediment contributed by rutile and its polymorphs, anatase and brookite, it was necessary to eliminate as many of the other minerals as possible, especially titanium-bearing minerals such as ilmenite, ilmenomagnetite, biotite, hornblende, oyroxene, and sphene. We accomplished this by developing a method of chemical dissolution that removed the bulk of the raw material and left the TiO 2 minerals intact. Many methods using acids and bases have been developed over the years to dissolve rocks, minerals, and sediments for chemical analysis or to concentrate specific minerals (Dolcater et al., 1970; Church, 1971; Campbell, 1973, and the references cited therein). The method developed by Raman and Jackson (1965) to concentrate rutile and anatase in soils and sediments requires digesting the sample in concentrated hydrofluoric acid (HF) for 24 hours. However, Campbell (1973) found that digestion in HF for more than 2 hours results in a loss of anatase. The method of Dolcater et al. (1970) for concentrating titanium as a free oxide requires the use of hydrofluotitanic acid (H 2 TiF 6 ), which is difficult to find on the commercial market. The acid can be prepared by the reaction of concentrated HF (48%) with an excess of TiO 2 , but the procedure requires 36 hours to complete and should be attempted with caution because it is highly exothermic. Jackson (1979) provides a detailed method for digesting soils, but many of the recommended pretreatment steps employ sodium compounds such as sodium bicarbonate (NaHCO 3 ), sodium citrate (Na 3 C 6 H 5 O 7 -2H 2 O), and sodium dithionate (Na 2 S 2 O 4 ), which are used for the removal of calcium carbonate, iron oxides, and phosphates. In combining the methods of Dolcater and Jackson, sodium compounds must be thoroughly washed from the sample because they form sodium fluotitanate (Na 2 TiF 6 ) in the presence of hydrofluotitanic acid (Fig. 1K). French and Adams (1973) described an inexpensive method for decomposing silicates by HF digestion in polypropylene containers. Their technique was effective for a wide variety of rock types. However, it did not address the problem caused by the precipitation of insoluble fluorides, nor did it outline a procedure to concentrate any residue that remained. As no one method gave the results we required, we modified procedures described in the literature and developed a process that removes 96 to 98 wt percent of the raw sample material. The residue is composed of rutile and minor amounts of micro- and cryptocrystalline TiO 2 (Fig. 1A-J), barite (Fig. 1L), elemental carbon (coal), and insoluble fluorides (Fig. 1J). The fluorides precipitate during the decomposition of siliceous material in hydrofluoric acid (e.g., MgF 2 and MgAlF 5 -2.7H 2 O; Lanmyhr and Kringstad, 1966). Most of the sample analyzed by the method described were marine muds collected from the Gulf of Maine (Valentine and Commeau, 1990). The silt and clay fraction (up to 99 wt% of the sediment) is composed of clay minerals (chiefly illite-mica and chlorite), silt-size quartz and feldspar, and small crystals (2-12 um) of rutile and hematite. The bulk sediment samples contained an average of 2 to 3 wt percent CaCO 3 . Tiher samples analyzed include red and gray Carboniferous and Triassic sandstones and siltstones exposed around the Bay of Fundy region and Paleozoic sandstones, siltstones, and shales from northern Maine and New Brunswick. These rocks are probable sources for the fine-grained rutile found in the Gulf of Maine.

Economic Geology↗
USGS1999

Importance of microscopy in durability studies of solidified and stabilized contaminated soils

Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or achieved in a laboratory warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or archived in a laboratory, warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.

Soil Science Society of America Journal↗
USGS2007

USGS Digital Spectral Library splib06a

Introduction We have assembled a digital reflectance spectral library that covers the wavelength range from the ultraviolet to far infrared along with sample documentation. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purpose of using spectral features for the remote detection of these and similar materials. Analysis of spectroscopic data from laboratory, aircraft, and spacecraft instrumentation requires a knowledge base. The spectral library discussed here forms a knowledge base for the spectroscopy of minerals and related materials of importance to a variety of research programs being conducted at the U.S. Geological Survey. Much of this library grew out of the need for spectra to support imaging spectroscopy studies of the Earth and planets. Imaging spectrometers, such as the National Aeronautics and Space Administration (NASA) Airborne Visible/Infra Red Imaging Spectrometer (AVIRIS) or the NASA Cassini Visual and Infrared Mapping Spectrometer (VIMS) which is currently orbiting Saturn, have narrow bandwidths in many contiguous spectral channels that permit accurate definition of absorption features in spectra from a variety of materials. Identification of materials from such data requires a comprehensive spectral library of minerals, vegetation, man-made materials, and other subjects in the scene. Our research involves the use of the spectral library to identify the components in a spectrum of an unknown. Therefore, the quality of the library must be very good. However, the quality required in a spectral library to successfully perform an investigation depends on the scientific questions to be answered and the type of algorithms to be used. For example, to map a mineral using imaging spectroscopy and the mapping algorithm of Clark and others (1990a, 2003b), one simply needs a diagnostic absorption band. The mapping system uses continuum-removed reference spectral features fitted to features in observed spectra. Spectral features for such algorithms can be obtained from a spectrum of a sample containing large amounts of contaminants, including those that add other spectral features, as long as the shape of the diagnostic feature of interest is not modified. If, however, the data are needed for radiative transfer models to derive mineral abundances from reflectance spectra, then completely uncontaminated spectra are required. This library contains spectra that span a range of quality, with purity indicators to flag spectra for (or against) particular uses. Acquiring spectral measurements and performing sample characterizations for this library has taken about 15 person-years of effort. Software to manage the library and provide scientific analysis capability is provided (Clark, 1980, 1993). A personal computer (PC) reader for the library is also available (Livo and others, 1993). The program reads specpr binary files (Clark, 1980, 1993) and plots spectra. Another program that reads the specpr format is written in IDL (Kokaly, 2005). In our view, an ideal spectral library consists of samples covering a very wide range of materials, has large wavelength range with very high precision, and has enough sample analyses and documentation to establish the quality of the spectra. Time and available resources limit what can be achieved. Ideally, for each mineral, the sample analysis would include X-ray diffraction (XRD), electron microprobe (EM) or X-ray fluorescence (XRF), and petrographic microscopic analyses. For some minerals, such as iron oxides, additional analyses such as Mossbauer would be helpful. We have found that to make the basic spectral measurements, provide XRD, EM or XRF analyses, and microscopic analyses, document the results, and complete an entry of one spectral library sample, all takes about

Data Series↗
USGS2010

Environmental investigations using diatom microfossils

Diatoms are unicellular phytoplankton (microscopic plant-like organisms) with cell walls made of silica (called a frustule). They live in both freshwater and saltwater and can be found in just about every place on Earth that is wet. The shape and morphology of the diatom frustule unique to each species are used for identification. Due to the microscopic size of diatoms, high-power microscopy is required for diatom identification. Diatoms are vital to life on Earth. They are photosynthetic primary producers, using sunlight to create oxygen and organic carbon from carbon dioxide and water. They are a significant source of the oxygen we breathe, have a major impact on the global carbon cycle (Smetacek, 1999), and are a food source for many aquatic organisms (Mann, 1993). Diatom abundance has even been demonstrated to have an influence on the diversity of larger marine mammals, including whales (Marx and Uhen, 2010). Data on diatom abundance and diversity are extremely useful in environmental studies.

Fact Sheet↗
USGS2000

MORPH-II, a software package for the analysis of scanning-electron-micrograph images for the assessment of the fractal dimension of exposed stone surfaces

Turcotte, 1997, and Barton and La Pointe, 1995, have identified many potential uses for the fractal dimension in physicochemical models of surface properties. The image-analysis program described in this report is an extension of the program set MORPH-I (Mossotti and others, 1998), which provided the fractal analysis of electron-microscope images of pore profiles (Mossotti and Eldeeb, 1992). MORPH-II, an integration of the modified kernel of the program MORPH-I with image calibration and editing facilities, was designed to measure the fractal dimension of the exposed surfaces of stone specimens as imaged in cross section in an electron microscope.

Open-File Report↗
USGS2015

Field and laboratory guide to freshwater cyanobacteria harmful algal blooms for Native American and Alaska Native communities

Cyanobacteria can produce toxins and form harmful algal blooms. The Native American and Alaska Native communities that are dependent on subsistence fishing have an increased risk of exposure to these cyanotoxins. It is important to recognize the presence of an algal bloom in a waterbody and to distinguish a potentially toxic harmful algal bloom from a non-toxic bloom. This guide provides field images that show cyanobacteria blooms, some of which can be toxin producers, as well as other non-toxic algae blooms and floating plants that might be confused with algae. After recognition of a potential toxin-producing cyanobacterial bloom in the field, the type(s) of cyanobacteria present needs to be identified. Species identification, which requires microscopic examination, may help distinguish a toxin-producer from a non-toxin producer. This guide also provides microscopic images of the common cyanobacteria that are known to produce toxins, as well as images of algae that form blooms but do not produce toxins.

Open-File Report↗
USGS2005

Characterization and modes of occurrence of elements in feed coal and coal combustion products from a power plant utilizing low-sulfur coal from the Powder River Basin, Wyoming

The U.S. Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana utility company to determine the physical and chemical properties of feed coal and coal combustion products from a coal-fired power plant. The Indiana power plant utilizes a low-sulfur (0.23 to 0.47 weight percent S) and lowash (4.9 to 6.3 weight percent ash) subbituminous coal from the Wyodak-Anderson coal zone in the Tongue River Member of the Paleocene Fort Union Formation, Powder River Basin, Wyoming. Based on scanning electron microscope and X-ray diffraction analyses of feed coal samples, two mineral suites were identified: (1) a primary or detrital suite consisting of quartz (including beta-form grains), biotite, feldspar, and minor zircon; and (2) a secondary authigenic mineral suite containing alumino-phosphates (crandallite and gorceixite), kaolinite, carbonates (calcite and dolomite), quartz, anatase, barite, and pyrite. The primary mineral suite is interpreted, in part, to be of volcanic origin, whereas the authigenic mineral suite is interpreted, in part, to be the result of the alteration of the volcanic minerals. The mineral suites have contributed to the higher amounts of barium, calcium, magnesium, phosphorus, sodium, strontium, and titanium in the Powder River Basin feed coals in comparison to eastern coals. X-ray diffraction analysis indicates that (1) fly ash is mostly aluminate glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals; and (2) bottom ash is predominantly quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite, and spinel group minerals. Microprobe and scanning electron microscope analyses of fly ash samples revealed quartz, zircon, and monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, wollastonite, and periclase. The abundant calcium and magnesium mineral phases in the fly ash are attributed to the presence of carbonate, clay, and phosphate minerals in the feed coal and their alteration to new phases during combustion. The amorphous diffraction-scattering maxima or glass 'hump' appears to reflect differences in chemical composition of fly ash and bottom ash glasses. In Wyodak-Anderson fly and bottom ashes, the center point of scattering maxima is due to calcium and magnesium content, whereas the glass 'hump' of eastern fly ash reflects variation in aluminum content. The calcium- and magnesium-rich and alumino-phosphate mineral phases in the coal combustion products can be attributed to volcanic minerals deposited in peat-forming mires. Dissolution and alteration of these detrital volcanic minerals occurred either in the peat-forming stage or during coalification and diagenesis, resulting in the authigenic mineral suite. The presence of free lime (CaO) in fly ash produced from Wyodak-Anderson coal acts as a self-contained 'scrubber' for SO3, where CaO + SO3 form anhydrite either during combustion or in the upper parts of the boiler. Considering the high lime content in the fly ash and the resulting hydration reactions after its contact with water, there is little evidence that major amounts of leachable metals are mobilized in the disposal or utilization of this fly ash.

Scientific Investigations Report↗
USGS2023

Effects of lead exposure on birds breeding in the Southeast Missouri Lead Mining District

Lead mining in the Southeast Missouri Lead Mining District began in the 1700s and continued for nearly 300 years; the waste piles associated with smelting, mining, and milling of lead ores have released metal residues that have contaminated soil and water in the region. Previous studies in the district have indicated potential harm to wildlife, including birds, because of elevated lead concentrations associated with mining. Exposure to soil-borne lead was correlated with elevated lead concentrations in tissues, inhibition of δ-aminolevulinic acid dehydratase (δALAD), and renal lesions in birds foraging on ground-dwelling invertebrates at contaminated sites (compared to reference sites) in the Southeast Missouri Lead Mining District. This study assessed reproductive outcomes for songbirds exposed to soil-borne lead in the district, examined the relation between lead concentrations in soils and in tissues of ground-feeding birds and prey species, and compared the results to literature-based toxicity thresholds for lead that are associated with negative effects in birds. Three lead-contaminated sites and three reference sites (with background concentrations of lead and no known mining inputs) were compared in two ways: individually to all other sites or by site type. Additional effects of lead exposure were evaluated by examining concentrations of biomarkers (oxidative stress, lipid peroxidation, and deoxyribonucleic acid damage) in liver tissues, δALAD inhibition, and renal and hepatic microscopic lesions in birds from lead-contaminated and reference sites. Lead concentrations in soil were site-dependent and were also generally heterogeneous within the lead-contaminated sites. Between 17 and 74 percent of all soil samples at contaminated sites had lead concentrations that exceeded a threshold (1,000 milligrams per kilogram [mg/kg] lead in soil) previously associated with adverse physiological effects in birds in the Southeast Missouri Lead Mining District. Lead concentrations in mixed invertebrates from lead-contaminated sites (282 to 2,230 mg/kg dry weight [dw]) indicated that consuming soil-dwelling prey species is a potential exposure pathway for adult birds and their broods. At lead-contaminated sites, lead concentrations in 40.5 percent of blood samples (adults and their broods) were within a subclinical effects range (0.9 to 2.3 mg/kg dw), and 18.7 percent of samples had lead concentrations that exceeded clinical effects criteria (greater than 2.3 mg/kg dw). In contrast, only 2.6 percent of blood samples from reference sites were within the subclinical effects range for lead; all other blood samples from the reference sites had lead concentrations representative of background concentrations (less than 0.9 mg/kg dw). Subclinical and clinical threshold exceedances for lead concentrations in livers and kidneys were similarly more prevalent at the contaminated sites compared to the reference sites. Lead concentrations in blood were positively correlated with lead concentrations in soil, livers, and kidneys. Lead concentrations in blood were negatively correlated with δALAD activity; greater than 50 percent of the birds collected at lead-contaminated sites exhibited injury via greater than 50 percent inhibition of δALAD in blood compared to birds at reference sites. Birds with elevated lead concentrations in tissues also exhibited enhanced oxidative stress. Microscopic lesions in the livers and kidneys of birds had similar rates of occurrence at the contaminated and reference sites, and lesion prevalence could not be directly linked to lead exposure. Reproductive success was monitored at 585 nests, and 3 out of 5 species had reduced nest success associated with elevated lead concentrations in soil; habitat measures did not help explain nest success. Reduced nest success may have resulted from greater nest predation resulting from neurological and behavioral effects of lead exposure. Ultimately, these lines of evidence indicate that bird health and reproduction have been negatively affected by exposure to lead-contaminated soils in the Southeast Missouri Lead Mining District.

Missouri↗
USGS2024

Cytology in cnidaria using Exaiptasia as a model

A need exists for additional methods to examine cnidaria at the cellular level to aid our understanding of health, anatomy, and physiology of this important group of organisms. This need is particularly acute given that disease is emerging as a major factor in declines of ecologically important functional groups such as corals. Here we describe a simple method to process cnidarian cells for microscopic examination using the model organism Exaiptasia . We show that this organism has at least 18 cell types or structures that can be readily distinguished based on defined morphological features. Some of these cells can be related back to anatomic features of the animal both at the light microscope and ultrastructural level. The cnidome of Exaiptasia may be more complex than what is currently understood. Moreover, cnidarian cells, including some types of cnidocytes, phagocytize cells other than endosymbionts. Finally, our findings shed light on morphologic complexity of cell-associated microbial aggregates and their intimate intracellular associations. The tools described here could be useful for other cnidaria.

Diseases of Aquatic Organisms↗