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At least 955 records · Page 53Linked to original sources
USGS1951

Fluorometric determination of zirconium in minerals

The increasing use of zirconium in alloys and in the ceramics industry has created renewed interest in methods for its determination. It is a common constituent of many minerals, but is usually present in very small amounts. Published methods tend to be tedious, time-consuming, and uncertain as to accuracy. A new fluorometric procedure, which overcomes these objections to a large extent, is based on the blue fluorescence given by zirconium and flavonol in sulfuric acid solution. Hafnium is the only element that interferes. The sample is fused with borax glass and sodium carbonate and extracted with water. The residue is dissolved in sulfuric acid, made alkaline with sodium hydroxide to separate aluminum, and filtered. The precipitate is dissolved in sulfuric acid and electrolysed in a Melaven cell to remove iron. Flavonol is then added and the fluorescence intensity is measured with a photo-fluorometer. Analysis of seven standard mineral samples shows excellent results. The method is especially useful for minerals containing less than 0.25% zirconium oxide.

Analytical Chemistry↗
USGS2008

Validation of a serum immunoassay to measure progesterone and diagnose pregnancy in the West Indian manatee (Trichechus manatus)

The objective was to validate a high-sensitivity chemiluminescent assay of serum progesterone concentrations for pregnancy diagnosis in manatees. Assay analytical sensitivity was 0.1 ng/mL, with mean intra- and inter-assay coefficients of variation of 9.7 and 9.2%, respectively, and accuracy had a mean adjusted R2 of 0.98. Methods comparison (relative to Siemen's Coat-A-Count RIA) demonstrated r = 0.98, Deming regression slope of 0.95, and an intercept of 0.01. Based on ROC analysis, a progesterone concentration ???0.4 ng/mL was indicative of pregnancy. Assay results were not significantly altered by two freeze-thaw cycles of samples. Characteristic progesterone concentrations during pregnancy were Months 1-4 (1.7-4.7 ng/mL), 5-8 (???1.0 ng/mL), and 10 and 11 (0.3-0.5 ng/mL), whereas two late-pregnant females with impending abortion had progesterone concentrations of 0.1 ng/mL. Among pregnant females, maximum progesterone concentrations occurred in autumn (3.9 ?? 1.8 ng/mL), and were greater during all seasons than concentrations in non-pregnant females (0.1-0.2 ng/mL). Progesterone concentrations were also significantly higher in pregnant females than in non-pregnant females and males. This highly sensitive, specific, and diagnostic assay will be valuable for monitoring pregnancy and abortion in manatees. ?? 2008 Elsevier Inc.

Theriogenology↗
USGS2009

Evaluation of trap capture in a geographically closed population of brown treesnakes on Guam

1. Open population mark-recapture analysis of unbounded populations accommodates some types of closure violations (e.g. emigration, immigration). In contrast, closed population analysis of such populations readily allows estimation of capture heterogeneity and behavioural response, but requires crucial assumptions about closure (e.g. no permanent emigration) that are suspect and rarely tested empirically. 2. In 2003, we erected a double-sided barrier to prevent movement of snakes in or out of a 5-ha semi-forested study site in northern Guam. This geographically closed population of >100 snakes was monitored using a series of transects for visual searches and a 13 ?? 13 trapping array, with the aim of marking all snakes within the site. Forty-five marked snakes were also supplemented into the resident population to quantify the efficacy of our sampling methods. We used the program mark to analyse trap captures (101 occasions), referenced to census data from visual surveys, and quantified heterogeneity, behavioural response, and size bias in trappability. Analytical inclusion of untrapped individuals greatly improved precision in the estimation of some covariate effects. 3. A novel discovery was that trap captures for individual snakes consisted of asynchronous bouts of high capture probability lasting about 7 days (ephemeral behavioural effect). There was modest behavioural response (trap happiness) and significant latent (unexplained) heterogeneity, with small influences on capture success of date, gender, residency status (translocated or not), and body condition. 4. Trapping was shown to be an effective tool for eradicating large brown treesnakes Boiga irregularis (>900 mm snout-vent length, SVL). 5. Synthesis and applications. Mark-recapture modelling is commonly used by ecological managers to estimate populations. However, existing models involve making assumptions about either closure violations or response to capture. Physical closure of our population on a landscape scale allowed us to determine the relative importance of covariates influencing capture probability (body size, trappability periods, and latent heterogeneity). This information was used to develop models in which different segments of the population could be assigned different probabilities of capture, and suggests that modelling of open populations should incorporate easily measured, but potentially overlooked, parameters such as body size or condition. ?? 2008 The Authors.

Journal of Applied Ecology↗
USGS1955

The reproduction of lake trout in southern Lake Superior

The principal spawning grounds of lake trout (Salvelinus namaycush namaycush) in United States waters of southern Lake Superior are on rocky shoals at depths of less than 20 fathoms. Most spawning occurs in October and early November. Of the mature fish collected on or near the spawning grounds, 60 to 69 percent were males. Among mature fish the average length of females was greater than that of males; few males less than 24 inches or females less than 26 inches in total length were caught. Recoveries of lake trout tagged on the spawning grounds showed that some males remained in the immediate area for a period of several weeks during the spawning season. Marked fish showed a tendency to return during later years to spawning grounds on which they had been tagged, even though many of them ranged long distances between spawning seasons. The percentage of the total weight composed by gonads of maturing females collected in 1950 was 5.0 percent on August 11–30 and 12.3 percent on October 6–9, but this increase was not accompanied by an increase in the coefficient of condition. One volumetric and two gravimetric methods for estimating numbers of eggs in ovaries were evaluated. Some advantage in accuracy of estimate resulted from the drying of eggs in an oven before weighing on an analytical balance. Production of eggs by 70 lake trout ranging from 25.1 to 38.0 inches in total length and from 5.8 to 19.6 pounds in weight ranged from 2,476 to 17,119. Average production was 646 per pound of fish; this number was greater among fish 31.0 inches long or larger than for fish of smaller size. Thirteen fish identified by commercial fishermen as siscowets (Salvelinus namaycush siscowet) also showed extensive individual variation in numbers of eggs, although egg production tended to increase with increasing length and weight of the fish. A mature female siscowet as small as 16.5 inches long and a 15.7-inch mature male were collected about 45 miles north of Grand Marais, Michigan. Combined data from all collections showed that spawning of lake trout or siscowets may occur during at least 6 months of the year (June to November).

Transactions of the American Fisheries Society↗
USGS2002

Reconnaissance-level assessment of water quality near Flandreau, South Dakota

This report presents water-quality data that have been compiled and collected for a reconnaissance-level assessment of water quality near Flandreau, South Dakota. The investigation was initiated as a cooperative effort between the U.S. Geological Survey and the Flandreau Santee Sioux Tribe. Members of the Flandreau Santee Sioux Tribe have expressed concern that Tribal members residing in the city of Flandreau experience more health problems than the general population in the surrounding area. Prior to December 2000, water for the city of Flandreau was supplied by wells completed in the Big Sioux aquifer within the city of Flandreau. After December 2000, water for the city of Flandreau was supplied by the Big Sioux Community Water System from wells completed in the Big Sioux aquifer along the Big Sioux River near Egan, about 8 river miles downstream of Flandreau. There is some concern that the public and private water supplies provided by wells completed in the Big Sioux aquifer near the Big Sioux River may contain chemicals that contribute to the health problems. Data compiled from other investigations provide information about the water quality of the Big Sioux River and the Big Sioux aquifer in the Flandreau area from 1978 through 2001. The median, minimum, and maximum values are presented for fecal bacteria, nitrate, arsenic, and atrazine. Nitrate concentrations of water from Flandreau public-supply wells occasionally exceeded the Maximum Contaminant Level of 10 milligrams per liter for public drinking water. For this study, untreated-water samples were collected from the Big Sioux River in Flandreau and from five wells completed in the Big Sioux aquifer in and near Flandreau. Treated-water samples from the Big Sioux Community Water System were collected at a site about midway between the treatment facility near Egan and the city of Flandreau. The first round of sampling occurred during July 9-12, 2001, and the second round of sampling occurred during August 20-27, 2001. Samples were analyzed for a broad range of compounds, including major ions, nutrients, trace elements, pesticides, antibiotics, and organic wastewater compounds, some of which might cause adverse health effects after long-term exposure. Samples collected on August 27, 2001, from the Big Sioux River also were analyzed for human pharmaceutical compounds. The quality of the water in the Big Sioux River and the Big Sioux aquifer in the Flandreau area cannot be thoroughly characterized with the limited number of samples collected within a 2-month period, and for many analytes, neither drinking-water standards nor associations with adverse health effects have been established. Concentrations of some selected analytes were less than U.S. Environmental Protection Agency drinking-water standards at the time of the sampling, and concentrations of most organic compounds were less than the respective method reporting levels for most of the samples.

South Dakota↗
USGS2008

Basic Statistical Concepts and Methods for Earth Scientists

INTRODUCTION Statistics is the science of collecting, analyzing, interpreting, modeling, and displaying masses of numerical data primarily for the characterization and understanding of incompletely known systems. Over the years, these objectives have lead to a fair amount of analytical work to achieve, substantiate, and guide descriptions and inferences.

Open-File Report↗
USGS2006

Development of a murre (Uria spp.) egg control material

The Seabird Tissue Archival and Monitoring Project (STAMP) is a collaborative Alaska-wide effort by the US Fish and Wildlife Service's Alaska Maritime National Wildlife Refuge (USFWS/AMNWR), the US Geological Survey's Biological Resources Division (USGS/BRD), the Bureau of Indian Affairs Alaska Region Subsistence Branch (BIA/ARSB), and the National Institute of Standards and Technology (NIST) to monitor long-term (decadal) trends in environmental contaminants using seabird eggs. To support this effort, a matrix- (seabird egg) and concentration-specific control material was needed to ensure quality during analytical work. Although a herring gull egg quality assurance (HGQA) material is available from Environment Canada (EC), contaminant concentrations in this material tended to be higher than those observed in Alaskan murre (Uria spp.) eggs. Therefore, to prepare a more appropriate control material, a total of 12 common murre (U. aalge) and thick-billed murre (U. lomvia) eggs from four Bering Sea and Gulf of Alaska nesting locations were cryohomogenized to create 190 aliquots each containing approximately 6 g. This new control material was analyzed by different methods at NIST and EC facilities for the determination of concentrations and value assignment of 63 polychlorinated biphenyl (PCB) congeners, 20 organochlorine pesticides, and 11 polybrominated diphenyl ether (PBDE) congeners. The total PCB concentration is approximately 58 ng g -1 wet mass. Results obtained for analytes not listed on the certificates of analysis of the previously used control materials, HGQA and NIST's Standard Reference Material (SRM) 1946 Lake Superior Fish Tissue, are also presented. [Figure not available: see fulltext.]. ?? Springer-Verlag 2007.

Conference Paper↗
USGS2014

Exposure and food web transfer of pharmaceuticals in ospreys (Pandion haliaetus): Predictive model and empirical data

The osprey ( Pandion haliaetus ) is a well-known sentinel of environmental contamination, yet no studies have traced pharmaceuticals through the water&ndash;fish&ndash;osprey food web. A screening-level exposure assessment was used to evaluate the bioaccumulation potential of 113 pharmaceuticals and metabolites, and an artificial sweetener in this food web. Hypothetical concentrations in water reflecting &ldquo;wastewater effluent dominated&rdquo; or &ldquo;dilution dominated&rdquo; scenarios were combined with pH-specific bioconcentration factors (BCFs) to predict uptake in fish. Residues in fish and osprey food intake rate were used to calculate the daily intake (DI) of compounds by an adult female osprey. Fourteen pharmaceuticals and a drug metabolite with a BCF greater than 100 and a DI greater than 20&thinsp;&micro;g/kg were identified as being most likely to exceed the adult human therapeutic dose (HTD). These 15 compounds were also evaluated in a 40 day cumulative dose exposure scenario using first-order kinetics to account for uptake and elimination. Assuming comparable absorption to humans, the half-lives (t 1/2 ) for an adult osprey to reach the HTD within 40 days were calculated. For 3 of these pharmaceuticals, the estimated t 1/2 in ospreys was less than that for humans, and thus an osprey might theoretically reach or exceed the HTD in 3 to 7 days. To complement the exposure model, 24 compounds were quantified in water, fish plasma, and osprey nestling plasma from 7 potentially impaired locations in Chesapeake Bay. Of the 18 analytes detected in water, 8 were found in fish plasma, but only 1 in osprey plasma (the antihypertensive diltiazem). Compared to diltiazem detection rate and concentrations in water (10/12 detects, <method detection limits [MDL]&ndash;173&thinsp;ng/L), there was a lower detection frequency in fish (31/233 detects, <MDL&ndash;2400&thinsp;ng/L); however when present in fish, all values exceeded the maximum diltiazem concentration found in water. Diltiazem was found in all 69 osprey plasma samples (540&ndash;8630&thinsp;ng/L), with 41% of these samples exceeding maximum concentrations found in fish. Diltiazem levels in fish and osprey plasma were below the human therapeutic plasma concentration (30&thinsp;000&thinsp;ng/L). Effect thresholds for diltiazem are unknown in ospreys at this time, and there is no evidence to suggest adverse effects. This screening-level exposure model can help identify those compounds that warrant further investigation in high-trophic level species.

Integrated Environmental Assessment and Management↗
USGS2013

Demographics of reintroduced populations: estimation, modeling, and decision analysis

Reintroduction can be necessary for recovering populations of threatened species. However, the success of reintroduction efforts has been poorer than many biologists and managers would hope. To increase the benefits gained from reintroduction, management decision making should be couched within formal decision-analytic frameworks. Decision analysis is a structured process for informing decision making that recognizes that all decisions have a set of components—objectives, alternative management actions, predictive models, and optimization methods—that can be decomposed, analyzed, and recomposed to facilitate optimal, transparent decisions. Because the outcome of interest in reintroduction efforts is typically population viability or related metrics, models used in decision analysis efforts for reintroductions will need to include population models. In this special section of the Journal of Wildlife Management, we highlight examples of the construction and use of models for informing management decisions in reintroduced populations. In this introductory contribution, we review concepts in decision analysis, population modeling for analysis of decisions in reintroduction settings, and future directions. Increased use of formal decision analysis, including adaptive management, has great potential to inform reintroduction efforts. Adopting these practices will require close collaboration among managers, decision analysts, population modelers, and field biologists.

Journal of Wildlife Management↗
USGS1989

Aeromagnetic maps of the Uinta and Piceance Basins and vicinity, Utah and Colorado

In order to understand the evolution of sedimentary basins, it is important to understand their tectonic setting. In a U.S. Geological Survey (USGS) study of the Uinta and Piceance basins in Utah and Colorado, this understanding is approached through characterization of subsurface structure and lithology of a large region encompassing the basins. An important tool for interpreting these subsurface features is aeromagnetic data. Aeromagnetic anomalies represent variations in the strength and direction of the Earth's magnetic field that are produced by rocks containing a significant number of magnetic minerals (commonly magnetite). The shape and magnitude of an anomaly produced by one body of rock are complexly related to the amount of magnetic minerals present, the magnetic properties of those minerals (determined by a number of factors, including the history of the rock), and the shape of the rock body. In the study area, only crystalline basement rocks and volcanic rocks are likely to contain enough magnetic minerals to produce anomalies; sedimentary rocks and metasediments are generally so poor in magnetic minerals that their magnetic effects cannot be detected by the types of surveys presented in this report. Patterns of anomalies on aeromagnetic maps can reveal not only lithologic differences related to magnetite content, but structural features as well, such as faults that have juxtaposed crystalline rocks against sedimentary rocks, and upwarps of crystalline basement underlying sedimentary sequences. Tectonic features of regional extent may not become apparent until a number of aeromagnetic surveys have been compiled and plotted at the same scale. Commonly the compilation involves piecing together data from surveys that were flown at different times and have widely disparate flight specifications and data reduction procedures. The data may be compiled into a composite map, where all the pieces are plotted onto one map without regard to the differences in flight elevation and datum, or they may be compiled into a merged map, where all survey data are analytically reduced to a common flight elevation and datum, and then digitally merged at the survey boundaries. The composite map retains the original resolution of all survey data, but computer methods to enhance or model regional features crossing the survey boundaries cannot be applied. On the other hand, these computer methods can be applied to the merged data, but the resolution of the data may be somewhat diminished. This report presents both composite and merged aeromagnetic maps for a large region that includes the Uinta Basin in Utah and the Piceance basin in Colorado (fig. 1).

Colorado;Utah↗
USGS1977

Uranium, radium, and selected metallic-element analyses of spring water and travertine samples from the Grand Canyon, Arizona

Samples for this report were collected from springs and travertine deposits along the Colorado River in the Grand Canyon, Arizona. Sampling was done in April and May of 1976. Data obtained from these samples will be used by R. A. Cadigan and J. K. Felmlee as part of a project designed to determine the value of subsurface waters in prospecting for uranium deposits. Sample sites were preselected at approximately equal intervals, but river conditions and accessibility forced some modification of the sampling plan at each spring visited, a 2-liter untreated water sample was collected to be analyzed for uranium and radium. At two of the sample locations, an additional 4-liter water sample was collected, filtered, acidified, and later analyzed for the 24 additional elements listed in table-2. A more detailed description of the sampling technique is presented in Brown and others, 1970. All samples were placed in full, tightly capped plastic containers. Temperature and conductivity were measured in the field. Measurements of the pH of the non-acidified samples were made in the laboratory a few weeks after the samples were collected. An effort was made to collect the freshest possible travertine samples, but the freshness of the samples varied, as noted in the descriptions of the sample sites. Analyses were performed by laboratories of the U.S. Geological Survey. Radium values were determined by radiochemical methods; uranium, by extraction fluorometry; eU (equivalent uranium), by beta-gamma count; and other elements, by semiquantitative emission spectrography. Table 1 is a description of the sample sites. The analytical results for spring water are presented in table 2. Table 3 gives the analyses of the travertine samples.

Arizona↗
USGS1953

Method for determination of small amounts of rare earths and thorium in phosphate rocks

In laboratory investigations, interest developed in the possible rare-earth content of phosphate samples from Florida and the northwestern United States. Because of the difficulty of making chemical determinations of traces of individual rare earths, a combined chemical-spectrographic method was investigated. After removal of iron by the extraction of the chloride with ether, the rare earths and thorium are concentrated by double oxalate precipitation, using calcium as a carrier. The rare earths are freed from calcium by an ammonium hydroxide precipitation with a fixed amount of aluminum as a carrier. The aluminum also serves as an internal standard in the final spectrographic analysis. The method will determine from 0.02 to 2 mg. of each rare earth with an error no greater than 10%. The investigation has resulted in a fairly rapid and precise procedure, involving no special spectrographic setup. The method could be applied to other types of geologic materials with the same expected accuracy.

Analytical Chemistry↗
USGS1987

ANALYSIS OF ESTUARINE TRACER-GAS TRANSPORT AND DESORPTION.

The riverine tracer-gas technique provides a direct, reach-averaged measure of gas exchange, is fairly simple to implement, and is widely accepted for determining reaeration-rate coefficients in rivers. The method, however, is not directly applicable to flows having vertical density gradients. Consequently, studies were undertaken to develop and evaluate methods for obtaining surface-exchange coefficients from estuarine tracer-gas data. Reasonable estimates of the desorption coefficient (within 50 percent of the correct value) were obtained when an analytical solution of the transport equation was compared with data from a numerically simulated continuous release of tracer gas.

Conference Paper↗
USGS2013

Evaluating analytical approaches for estimating pelagic fish biomass using simulated fish communities

Pelagic fish assessments often combine large amounts of acoustic-based fish density data and limited midwater trawl information to estimate species-specific biomass density. We compared the accuracy of five apportionment methods for estimating pelagic fish biomass density using simulated communities with known fish numbers that mimic Lakes Superior, Michigan, and Ontario, representing a range of fish community complexities. Across all apportionment methods, the error in the estimated biomass generally declined with increasing effort, but methods that accounted for community composition changes with water column depth performed best. Correlations between trawl catch and the true species composition were highest when more fish were caught, highlighting the benefits of targeted trawling in locations of high fish density. Pelagic fish surveys should incorporate geographic and water column depth stratification in the survey design, use apportionment methods that account for species-specific depth differences, target midwater trawling effort in areas of high fish density, and include at least 15 midwater trawls. With relatively basic biological information, simulations of fish communities and sampling programs can optimize effort allocation and reduce error in biomass estimates.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1997

An automated HPLC method for the fractionation of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans in fish tissue on a porous graphitic carbon column

The Ah (aryl-hydrocarbon) hydroxylase-receptor active polychlorinated biphenyls (PCBs), polychlorinated dibenzo- p -dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were fractionated by an automated high-performance liquid chromatography (HPLC) system using the Hypercarb™ porous graphitic carbon (PGC) column. This commercially available column was used to fractionate the di-, mono-, and non- ortho PCBs into three fractions for gas chromatography (GC)/electron capture detection analysis, and a fourth fraction containing the PCDDs/PCDFs for GC/mass spectrometry analysis. The recoveries of the PCBs ranged from 68 to 96%, and recoveries of the PCDDs/PCDFs ranged from 74 to 123%. The PGC column has the advantage of faster separations (110 min versus 446 min) and less solvent use (275 ml versus 1,100 ml) compared with automated fractionation of these compounds on activated carbon (PX-21), while still affording good separation of the classes. The PGC column may have an advantage over the pyrenyl-based HPLC method because it has a greater loading capacity (400 μg total PCBs versus 250 μg). Overall, the PGC is a standard column that provides reproducible fractionation of PCDD/PCDFs and PCBs for analytical measurement in environmental samples.

Environmental Toxicology and Chemistry↗
USGS2017

Translating statistical species-habitat models to interactive decision support tools

Understanding species-habitat relationships is vital to successful conservation, but the tools used to communicate species-habitat relationships are often poorly suited to the information needs of conservation practitioners. Here we present a novel method for translating a statistical species-habitat model, a regression analysis relating ring-necked pheasant abundance to landcover, into an interactive online tool. The Pheasant Habitat Simulator combines the analytical power of the R programming environment with the user-friendly Shiny web interface to create an online platform in which wildlife professionals can explore the effects of variation in local landcover on relative pheasant habitat suitability within spatial scales relevant to individual wildlife managers. Our tool allows users to virtually manipulate the landcover composition of a simulated space to explore how changes in landcover may affect pheasant relative habitat suitability, and guides users through the economic tradeoffs of landscape changes. We offer suggestions for development of similar interactive applications and demonstrate their potential as innovative science delivery tools for diverse professional and public audiences.

PLoS ONE↗
USGS1988

Aeromagnetic maps of the Colorado River region including the Kingman, Needles, Salton Sea, and El Centro 1 degree by 2 degrees quadrangles, California, Arizona, and Nevada

Aeromagnetic data for the Colorado river region have been compiled as part of the Pacific to Arizona Crustal Experiment (PACE) Project. The data are presented here in a series of six compilations for the Kingman, Needles, Salton Sea, and El Centro 1 degree by 2 degree quadrangles, California, Arizona, and Nevada, at scales of 1:250,000 and 1:750,000. The scales and map areas are identical to those used by Mariano and others (1986) to display the Bouguer and isotatic residual gravity for this region. Data were compiled separately for the Kingman quadrangle, the Needles quadrangle, and an area covering the Salton Sea quadrangle and part of the El Centro quadrangle. Aeromagnetic anomalies are produced by variations in the strength and direction of the magnetic field of rocks that include magnetic minerals, commonly magnetite. Patterns of anomalies on aeromagnetic maps can reveal structures - for example, faults which have juxtaposed magnetic rocks against non-magnetic rocks, or areas of alteration where magnetic minerals have been destroyed by hydrothermal activity. Tectonic features of regional extent may not become apparent until a number of aeromagnetic surveys have been compiled and plotted at the same scale. Commonly the compilation involves piecing together data from surveys that were flown at different times with widely disparate flight specifications and data reduction procedures. The data may be compiled into a composite map, where all the pieces are plotted onto one map without regard to the difference in flight elevation and datum, or they may be compiled into a merged map, where all survey data are analytically reduced to a common flight elevation and datum, and then digitally merged at the survey boundaries. The composite map retains the original resolution of all the survey data, but computer methods to enhance regional features crossing the survey boundaries may not be applied. On the other hand, computer methods can be applied to the merged data, but the accuracy of the data may be slightly diminished.

Arizona, California, Nevada↗