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At least 451 records · Page 25Linked to original sources
USGS2012

Automated measurement of diatom size

Size analysis of diatom populations has not been widely considered, but it is a potentially powerful tool for understanding diatom life histories, population dynamics, and phylogenetic relationships. However, measuring cell dimensions on a light microscope is a time-consuming process. An alternative technique has been developed using digital flow cytometry on a FlowCAM® (Fluid Imaging Technologies) to capture hundreds, or even thousands, of images of a chosen taxon from a single sample in a matter of minutes. Up to 30 morphological measures may be quantified through post-processing of the high resolution images. We evaluated FlowCAM size measurements, comparing them against measurements from a light microscope. We found good agreement between measurement of apical cell length in species with elongated, straight valves, including small Achnanthidium minutissimum (11-21 µm) and large Didymosphenia geminata (87–137 µm) forms. However, a taxon with curved cells, Hannaea baicalensis (37–96 µm), showed differences of ~ 4 µm between the two methods. Discrepancies appear to be influenced by the choice of feret or geodesic measurement for asymmetric cells. We describe the operating conditions necessary for analysis of size distributions and present suggestions for optimal instrument conditions for size analysis of diatom samples using the FlowCAM. The increased speed of data acquisition through use of imaging flow cytometers like the FlowCAM is an essential step for advancing studies of diatom populations.

Limnology and Oceanography: Methods↗
USGS2013

On the absolute calibration of SO 2 cameras

Sulphur dioxide emission rate measurements are an important tool for volcanic monitoring and eruption risk assessment. The SO 2 camera technique remotely measures volcanic emissions by analysing the ultraviolet absorption of SO 2 in a narrow spectral window between 300 and 320 nm using solar radiation scattered in the atmosphere. The SO 2 absorption is selectively detected by mounting band-pass interference filters in front of a two-dimensional, UV-sensitive CCD detector. One important step for correct SO 2 emission rate measurements that can be compared with other measurement techniques is a correct calibration. This requires conversion from the measured optical density to the desired SO 2 column density (CD). The conversion factor is most commonly determined by inserting quartz cells (cuvettes) with known amounts of SO 2 into the light path. Another calibration method uses an additional narrow field-of-view Differential Optical Absorption Spectroscopy system (NFOVDOAS), which measures the column density simultaneously in a small area of the camera’s field-of-view. This procedure combines the very good spatial and temporal resolution of the SO 2 camera technique with the more accurate column densities obtainable from DOAS measurements. This work investigates the uncertainty of results gained through the two commonly used, but quite different, calibration methods (DOAS and calibration cells). Measurements with three different instruments, an SO 2 camera, a NFOVDOAS system and an Imaging DOAS (I-DOAS), are presented. We compare the calibration-cell approach with the calibration from the NFOV-DOAS system. The respective results are compared with measurements from an I-DOAS to verify the calibration curve over the spatial extent of the image. The results show that calibration cells, while working fine in some cases, can lead to an overestimation of the SO 2 CD by up to 60% compared with CDs from the DOAS measurements. Besides these errors of calibration, radiative transfer effects (e.g. light dilution, multiple scattering) can significantly influence the results of both instrument types. The measurements presented in this work were taken at Popocatepetl, Mexico, between 1 March 2011 and 4 March 2011. Average SO 2 emission rates between 4.00 and 14.34 kg s −1 were observed.

Atmospheric Measurement Techniques↗
USGS2001

Immune status of free-ranging green turtles with fibropapillomatosis from Hawaii

Cell-mediated and humoral immune status of free-ranging green turtles ( Chelonia mydas ) in Hawaii (USA) with and without fibropapillomatosis (FP) were assessed. Tumored and non-tumored turtles from Kaneohe Bay (KB) on the island of Oahu and from FP-free areas on the west (Kona/Kohala) coast of the island of Hawaii were sampled from April 1998 through February 1999. Turtles on Oahu were grouped (0–3) for severity of tumors with 0 for absence of tumors, 1 for light, 2 for moderate, and 3 for most severe. Turtles were weighed, straight carapace length measured and the regression slope of weight to straight carapace length compared between groups (KB0, KB1, KB2, KB3, Kona). Blood was assayed for differential white blood cell count, hematocrit, in vitro peripheral blood mononuclear cell (PBMC) proliferation in the presence of concanavalin A (ConA) and phytohaemagglutinin (PHA), and protein electrophoresis. On Oahu, heterophil/lymphocyte ratio increased while eosinophil/monocyte ratio decreased with increasing tumors score. Peripheral blood mononuclear cell proliferation indices for ConA and PHA were significantly lower for turtles with tumor scores 2 and 3. Tumor score 3 turtles (KB3) had significantly lower hematocrit, total protein, alpha 1, alpha 2, and gamma globulins than the other four groups. No significant differences in immune status were seen between non-tumored (or KB1) turtles from Oahu and Hawaii. There was no significant difference between groups in regression slopes of body condition to carapace length. We conclude that turtles with severe FP are imunosuppressed. Furthermore, the lack of significant difference in immune status between non-tumored (and KB1) turtles from Oahu and Kona/Kohala indicates that immunosuppression may not be a prerequisite for development of FP.

Hawai'i↗
USGS1997

Detecting contaminant-induced apoptosis and necrosis in lake trout thymocytes via flow cytometry.

This chapter details the cytofluorometric techniques employed to assess levels of active (apoptosis) and passive (necrotic) cell death in untreated and contaminant-treated fish thymocytes. The thymus is believed to be a central component of hematopoiesis and immune function in teleosts (Abelli et al., 1996). Hence, chemically-elicited adverse effects to the thymus may result in immunomodulation and organ dysfunction. However, it is not well documented that environmental contaminants induce apoptosis, or programmed cell death. There is some evidence suggesting that low level exposure to waterborne contaminants can specifically induce cell death in the olfactory epithelium of rainbow trout (Julliard et al., 1996). Presently, only limited information is available in the literature regarding apoptotic death in piscine immune cells (Alford et al., 1994; Greenlee et al., 1991).

Book chapter↗
USGS1997

Distribution of autumn-staging Lesser Snow Geese on the northeast coastal plain of Alaska

We conducted aerial surveys of Lesser Snow Geese ( Chen caerulescens caerulescens ) during autumn staging on the coastal plain of the Arctic National Wildlife Refuge (ANWR) in northeast Alaska from late August through September, 1982 - 1993. We evaluated numbers and distribution of Snow Geese that staged on the ANWR, compared abundance of birds among 5 x 5-km cells used frequently (5 - 8 yr), periodically (3 - 4 yr), or infrequently (1 - 2 yr), and examined distribution changes within years. Maximum numbers of Snow Geese observed annually were highly variable (range 12,828 - 309,225). Snow Goose flocks occurred across 605,000 ha of the coastal plain, but used some areas more frequently than others. Frequently used cells (38 of 363 cells in the study area) were non-randomly distributed and primarily occurred on the central coastal plain between the wet coastal and steep foothills regions. Abundance of geese was greatest in frequently used, intermediate in periodically used, and lowest in infrequently used cells. Within years, Snow Goose numbers and flock locations varied between surveys, possibly because geese moved to different foraging areas during staging. The widespread distribution and annual variability in numbers of Snow Geese on the coastal plain was likely because birds used foraging habitats that were spatially and temporally heterogeneous. The ANWR coastal plain is an important component of the fall-staging area used by Snow Geese that nest in the western Canadian Arctic. Management decisions that affect the region should reflect its value to migrating Snow Geese.

Alaska↗
USGS2000

Test functions for three-dimensional control-volume mixed finite-element methods on irregular grids

Numerical methods based on unstructured grids, with irregular cells, usually require discrete shape functions to approximate the distribution of quantities across cells. For control-volume mixed finite-element methods, vector shape functions are used to approximate the distribution of velocities across cells and vector test functions are used to minimize the error associated with the numerical approximation scheme. For a logically cubic mesh, the lowest-order shape functions are chosen in a natural way to conserve intercell fluxes that vary linearly in logical space. Vector test functions, while somewhat restricted by the mapping into the logical reference cube, admit a wider class of possibilities. Ideally, an error minimization procedure to select the test function from an acceptable class of candidates would be the best procedure. Lacking such a procedure, we first investigate the effect of possible test functions on the pressure distribution over the control volume; specifically, we look for test functions that allow for the elimination of intermediate pressures on cell faces. From these results, we select three forms for the test function for use in a control-volume mixed method code and subject them to an error analysis for different forms of grid irregularity; errors are reported in terms of the discrete L2 norm of the velocity error. Of these three forms, one appears to produce optimal results for most forms of grid irregularity.

Conference Paper↗
USGS2006

Non-invasive method to obtain DNA from freshwater mussels (Bivalvia: Unionidae)

To determine whether DNA could be isolated from tissues obtained by brush-swabbing the mantle, viscera and foot, mantle-clips and swabbed cells were obtained from eight Quadrula pustulosa (Lea, 1831). DNA yields from clips and swabbings were 447.0 and 975.3 ??g/??L, respectively. Furthermore, comparisons of sequences from the ND-1 mitochondrial gene region showed a 100% sequence agreement of DNA from cells obtained by clips and swabs. To determine the number of swabs needed to obtain adequate yields of DNA for analyses, the visceras and feet of 5 Q. pustulosa each were successively swabbed 2, 4 and 6 times. DNA yields from the 2, 4 and 6 swabbed mussel groups were 399.4, 833.8 and 852.6 ng/??L, respectively. ND-1 sequences from the lowest yield still provided 846-901 bp for the ND-1 region. Nevertheless, to ensure adequate DNA yield from cell samples obtained by swabbing, we recommend that 4 swab-strokes of the viscera and foot be obtained. The use of integumental swabbing for collection of cells for determination of genetic relationships among freshwater mussels is noninvasive, when compared with tissue collection by mantle-clipping. Therefore, its use is recommended for freshwater mussels, especially state-protected or federally listed mussel species.

Journal of Shellfish Research↗
USGS2013

Urban runoff (URO) process for MODFLOW 2005: simulation of sub-grid scale urban hydrologic processes in Broward County, FL

Climate change and sea-level rise could cause substantial changes in urban runoff and flooding in low-lying coast landscapes. A major challenge for local government officials and decision makers is to translate the potential global effects of climate change into actionable and cost-effective adaptation and mitigation strategies at county and municipal scales. A MODFLOW process is used to represent sub-grid scale hydrology in urban settings to help address these issues. Coupled interception, surface water, depression, and unsaturated zone storage are represented. A two-dimensional diffusive wave approximation is used to represent overland flow. Three different options for representing infiltration and recharge are presented. Additional features include structure, barrier, and culvert flow between adjacent cells, specified stage boundaries, critical flow boundaries, source/sink surface-water terms, and the bi-directional runoff to MODFLOW Surface-Water Routing process. Some abilities of the U rban R un O ff (URO) process are demonstrated with a synthetic problem using four land uses and varying cell coverages. Precipitation from a hypothetical storm was applied and cell by cell surface-water depth, groundwater level, infiltration rate, and groundwater recharge rate are shown. Results indicate the URO process has the ability to produce time-varying, water-content dependent infiltration and leakage, and successfully interacts with MODFLOW.

Florida↗
USGS2014

Viral erythrocytic necrosis

Viral erythrocytic necrosis (VEN), originally termed piscine erythrocytic necrosis, is a condition that has been reported to affect the red blood cells (RBCs) of many species of marine and anadromous fishes in both the Atlantic and Pacific Oceans (Nicholson and Reno 1981; Smail 1982; Wolf 1988; Dannevig and Thorud 1999). Fish with VEN may develop a severe anemia that can reduce their stamina, predispose them to other infections or increase the impact of other stressors (MacMillan et al. 1980; Nicholson and Reno 1981; Meyers et al. 1986; Haney et al. 1992) resulting in population-scale impacts in susceptible species (Hershberger et al. 2009). In spite of extensive efforts, the etiological agent of VEN has not been propagated in fish cell lines making its characterization difficult. However, transmission electron microscopy (TEM) of red blood cells from diseased fish convincingly demonstrates the presence of iridovirus-like particles that have been given the name erythrocytic necrosis virus (ENV). While the ENV virions in red blood cells of various species of fish from differing geographic locations may appear morphologically distinct (Smail 1982; Wolf 1988), at least one strain of ENV has now been partially sequenced, confirming it to be a member of the family Iridoviridae (Emmenegger et al. in press). However, the genetic relatedness of ENV from various fish hosts has not yet been investigated.

Book chapter↗
USGS2015

Mixing effects on nitrogen and oxygen concentrations and the relationship to mean residence time in a hyporheic zone of a riffle-pool sequence

Flow paths and residence times in the hyporheic zone are known to influence biogeochemical processes such as nitrification and denitrification. The exchange across the sediment-water interface may involve mixing of surface water and groundwater through complex hyporheic flow paths that contribute to highly variable biogeochemically active zones. Despite the recognition of these patterns in the literature, conceptualization and analysis of flow paths and nitrogen transformations beneath riffle-pool sequences often neglect to consider bed form driven exchange along the entire reach. In this study, the spatial and temporal distribution of dissolved oxygen (DO), nitrate (NO 3 - ) and ammonium (NH 4 + ) were monitored in the hyporheic zone beneath a riffle-pool sequence on a losing section of the Truckee River, NV. Spatially-varying hyporheic exchange and the occurrence of multi-scale hyporheic mixing cells are shown to influence concentrations of DO and NO 3 - and the mean residence time (MRT) of riffle and pool areas. Distinct patterns observed in piezometers are shown to be influenced by the first large flow event following a steady 8 month period of low flow conditions. Increases in surface water discharge resulted in reversed hydraulic gradients and production of nitrate through nitrification at small vertical spatial scales (0.10 to 0.25 m) beneath the sediment-water interface. In areas with high downward flow rates and low MRT, denitrification may be limited. The use of a longitudinal two-dimensional flow model helped identify important mechanisms such as multi-scale hyporheic mixing cells and spatially varying MRT, an important driver for nitrogen transformation in the riverbed. Our observations of DO and NO 3 - concentrations and model simulations highlight the role of multi-scale hyporheic mixing cells on MRT and nitrogen transformations in the hyporheic zone of riffle-pool sequences. This article is protected by copyright. All rights reserved.

Water Resources Research↗
USGS2023

Susceptibility of Pallid Sturgeon to viral hemorrhagic septicemia virus genotype IVb

Objective Viral hemorrhagic septicemia virus (VHSV) is an aquatic rhabdovirus causing severe disease in freshwater and saltwater fish species. The susceptibility of endangered Pallid Sturgeon Scaphirhynchus albus to VHSV genotype IVb (VHSV-IVb) infection was investigated. Methods An in vitro assessment using two Pallid Sturgeon cell lines derived from skin and spleen tissue and in vivo evaluation of juvenile Pallid Sturgeon after exposure to VHSV-IVb were performed. Result Plaque assay and RT-PCR results confirmed VHSV-IVb replication in Pallid Sturgeon cell lines. Sturgeon were also susceptible to VHSV-IVb infection after immersion and injection exposures during laboratory experiments. However, after widespread mortality occurred in all treatment groups, including negative control fish, it was determined that the Pallid Sturgeon stock fish were infected with Missouri River sturgeon iridovirus (MRSIV) prior to experimental challenge. Nevertheless, mortalities were equal or higher among VHSV-exposed fish than among negative controls (MRSIV infected), and histopathological assessments indicated reduced hematopoietic cells in spleen and kidney tissues and hemorrhage in the gastrointestinal organs only in fish from the VHSV treatment. Conclusion These results indicate that Pallid Sturgeon is a susceptible host for VHSV-IVb, but the degree of pathogenicity was confounded by the underlying MRSIV infection. Research comparing susceptibility of specific pathogen-free and MRSIV-infected fish to VHSV-IVb is needed to accurately assess the vulnerability of Pallid Sturgeon to VHSV-IVb.

Journal of Aquatic Animal Health↗
USGS2005

Cortisol receptor blockade and seawater adaptation in the euryhaline teleost Fundulus heteroclitus

To examine the role of cortisol in seawater osmoregulation in a euryhaline teleost, adult killifish were acclimated to brackish water (10???) and RU486 or vehicle was administered orally in peanut oil daily for five days at low (40 mg.kg-1) or high dose (200 mg.kg-1). Fish were transferred to 1.5 x seawater (45???) or to brackish water (control) and sampled at 24 h and 48 h after transfer, when Cl- secretion is upregulated. At 24 h, opercular membrane Cl- secretion rate, as Isc, was increased only in the high dose RU486 group. Stimulation of membranes by 3-isobutyl-1-methylxanthine and cAMP increased Isc in vehicle treated controls but those from RU486-treated animals were unchanged and membranes from brackish water animals showed a decrease in Isc. At 48 h, Isc increased and transepithelial resistance decreased in vehicle and RU486 groups, compared to brackish water controls. Plasma cortisol increased in all groups transferred to high salinity, compared to brackish water controls. RU486 treated animals had higher cortisol levels compared to vehicle controls. Vehicle treated controls had lower cortisol levels than untreated or RU486 treated animals, higher stimulation of Isc, and lower hematocrit at 24 h, beneficial effects attributed to increased caloric intake from the peanut oil vehicle. Chloride cell density was significantly increased in the high dose RU486 group at 48 hours, yet Isc was unchanged, suggesting a decrease in Cl- secretion per cell. Thus cortisol enhances NaCl secretion capacity in chloride cells, likely via glucocorticoid type receptors. ?? 2005 Wiley-Liss, Inc.

Journal of Experimental Zoology Part A: Comparativ↗
USGS2007

Differential expression and localization of four connexins in the ovary of the ayu (Plecoglossus Altivelis)

The post-vitellogenic oocytes of teleost fish are generally unresponsive to maturation-inducing hormone (MIH) until a luteinizing hormone (LH) surge stimulates sensitivity via the acquisition of oocyte-maturational competence (OMC). Heterologous gap junctions (GJs) between granulosa cells and the oocyte have been previously implicated in the regulation of oocyte maturation in various vertebrate species. Although heterologous GJ are present in ovarian follicles of ayu (Plecoglossus altivelis), their role in maturation remains unclear. In the present study, we cloned and characterized complementary DNAs for GJ protein connexin (Cx), and examined the expression pattern of Cx messenger RNAs in the ayu ovary. Four Cx cDNAs with predicted molecular masses of 32.1 (Cx32.1), 34.9 (Cx34.9), 44.1 (Cx44.1), and 44.2 (Cx44.2) kDa, respectively, were cloned. Northern blot analysis revealed that the levels of Cx44.1 and Cx44.2 transcripts were similar during the vitellogenic and ovulatory stages. Cx32.1 transcripts were more abundant during the vitellogenic stage, but their levels declined thereafter. Cx34.9 transcript levels increased during the vitellogenic stage and remained high during the acquisition of OMC. In situ hybridization revealed that Cx44.1 and Cx44.2 signals were restricted to the oocyte, whereas the Cx32.1 and Cx34.9 signals were detected in both cellular fractions. Furthermore, a dye-transfer assay revealed the presence of functional GJs between the oocytes and follicle cells. These results suggest that Cx34.9 contributes to the formation of heterologous GJs between oocytes and granulosa cells. Moreover, GJs formed by Cx34.9 may function during the LH-dependent acquisition of OMC and the MIH-dependent resumption of meiosis in ayu. ?? 2007 Wiley-Liss, Inc.

Molecular Reproduction and Development↗
USGS2006

Application and testing of a procedure to evaluate transferability of habitat suitability criteria

A procedure designed to test the transferability of habitat suitability criteria was evaluated in the Cache la Poudre River, Colorado. Habitat suitability criteria were developed for active adult and juvenile rainbow trout in the South Platte River, Colorado. These criteria were tested by comparing microhabitat use predicted from the criteria with observed microhabitat use by adult rainbow trout in the Cache la Poudre River. A one-sided X 2 test, using counts of occupied and unoccupied cells in each suitability classification, was used to test for non-random selection for optimum habitat use over usable habitat and for suitable over unsuitable habitat. Criteria for adult rainbow trout were judged to be transferable to the Cache la Poudre River, but juvenile criteria (applied to adults) were not transferable. Random subsampling of occupied and unoccupied cells was conducted to determine the effect of sample size on the reliability of the test procedure. The incidence of type I and type II errors increased rapidly as the sample size was reduced below 55 occupied and 200 unoccupied cells. Recommended modifications to the procedure included the adoption of a systematic or randomized sampling design and direct measurement of microhabitat variables. With these modifications, the procedure is economical, simple and reliable. Use of the procedure as a quality assurance device in routine applications of the instream flow incremental methodology was encouraged.

Colorado↗
USGS1998

Fish thymocyte viability, apoptosis and necrosis: In-vitro effects of organochlorine contaminants

The thymus is believed to be a central component of haematopoiesis and immune function in teleosts. Hence, chemically-elicited adverse effects to the thymus may result in immunomodulation and organ dysfunction. The objective of this research was to assess the levels of active (apoptotic) and passive (necrotic) cell death in untreated and organochlorine treated fish thymocytes. Lake trout ( Salvelinus namaycush ) thymocytes were challenged with Aroclor 1254 (concentration range 1·5–10·5 μg ml −1 ) and alpha, beta, gamma, delta isomers of hexachlorocyclohexane (concentration range 10–100 μ M ). The resulting maintenance or loss of viability was assessed by cytofluorometry (expression of phosphatidylserine and exclusion of propidium iodide) and confirmed with fluorescence microscopy. The results indicate that 20–60% of thymocytes in healthy fish undergo apoptosis, whereas thymocytes treated for 6–24 h with organochlorines exhibit increased levels of apoptotic cell death. This study demonstrates that given sufficient concentration, contact time and cellular receptors, organochlorines such as Aroclor 1254 and hexachloro-cyclohexanes may induce direct or indirect toxicity, altered functionality, or cell death to an organ important for fish immunocompetence.

Fish and Shellfish Immunology↗
USGS2003

Measurement of in vitro leucocyte mitogenesis in fish: ELISA based detection of the thymidine analogue 5'-bromo-2'-deoxyuridine

In this study we present a method for the measurement of in vitro mitogenesis in fish leucocytes that is based on the incorporation of the thymidine analogue 5′-bromo-2′-deoxyuridine (BrdU) into the DNA of replicating cells, followed by ELISA-based detection. This technique, adapted from methods developed for mammalian cells, operates on a similar biological principle to 3 H-thymidine incorporation, but circumvents the logistical and safety issues inherent with the radioactive label. Because it directly measures DNA proliferation, the assay has advantages over other colorimetric methods that may be strongly influenced by leucocyte metabolic status. Using BrdU incorporation followed by ELISA, we evaluate the responsiveness of rainbow trout ( Oncorhynchus mykiss [Walbaum]) leucocytes to the mammalian T-cell mitogen Concanavalin A (Con A) as well as the differential response of white perch ( Morone americana [Gmelin]) leucocytes to Con A and pokeweed mitogen. Specific considerations intrinsic to the assay system are discussed, including the implications of utilising enzyme-based detection.

Fish and Shellfish Immunology↗
USGS1989

Comparison of whole body and tissue blood volumes in rainbow trout (Salmo gairdneri) with 125 I bovine serum albumin and 51 Cr-erythrocyte tracers

Total, packed cell and, plasma volume estimates were made for the whole body and selected tissues of rainbow trout by the simultaneous injection of radiolabelled trout erythrocyte ( 51 Cr-RBC) and radioiodinated bovine serum albumin ( 125 I-BSA) tracers. Blood volumes were estimated with both markers separately by the tracer-hematocrit method and as the combination of the 51 Cr-RBC packed cell and 125 I-BSA plasma volumes. Mean whole body blood volume was significantly less when calculated from the 51 Cr-RBC tracer data (3.52±0.78 ml/100 g; ±SD) than when calculated with the 125 I-BSA tracer (5.06±0.86 ml/100 g) or as the sum of the two volumes combined (4.49±0.60 ml/100 g). The whole body hematocrit (28±5%), estimated as the quotient of the 51 Cr-RBC volume divided by the sum of the 125 I-BSA and the 51 Cr-RBC volumes, also was significantly less than the dorsal aortic microhematocrit (36±4%). Estimates of total blood volumes in most tissues were significantly smaller when calculated from the 51 Cr-RBC data than when calculated by the other two methods. Tissue blood volumes were greatest in highly vascularized and well perfused tissues and least in poorly vascularized tissues. The relative degree of vascularization among tissues generally remained the same regardless of whether the red cell or the plasma tracer was used to calculated blood volume. It is not clear whether the expanded plasma volume is the result of the distribution of erythrocyte-poor blood into the secondary circulation or the result of extravascular exchange of plasma proteins.

Fish Physiology and Biochemistry↗
USGS1994

An integrated data-directed numerical method for estimating the undiscovered mineral endowment in a region

An integrated data-directed numerical method has been developed to estimate the undiscovered mineral endowment within a given area. The method has been used to estimate the undiscovered uranium endowment in the San Juan Basin, New Mexico, U.S.A. The favorability of uranium concentration was evaluated in each of 2,068 cells defined within the Basin. Favorability was based on the correlated similarity of the geologic characteristics of each cell to the geologic characteristics of five area-related deposit models. Estimates of the undiscovered endowment for each cell were categorized according to deposit type, depth, and cutoff grade. The method can be applied to any mineral or energy commodity provided that the data collected reflect discovered endowment. ?? 1994 Oxford University Press.

Nonrenewable Resources↗