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USGS1989

Modification of a method-of-characteristics solute-transport model to incorporate decay and equilibrium-controlled sorption or ion exchange

The U.S. Geological Survey computer model of two-dimensional solute transport and dispersion in ground water (Konikow and Bredehoeft, 1978) has been modified to incorporate the following types of chemical reactions: (1) first-order irreversible rate-reaction, such as radioactive decay; (2) reversible equilibrium-controlled sorption with linear, Freundlich, or Langmuir isotherms; and (3) reversible equilibrium-controlled ion exchange for monovalent or divalent ions. Numerical procedures are developed to incorporate these processes in the general solution scheme that uses method-of- characteristics with particle tracking for advection and finite-difference methods for dispersion. The first type of reaction is accounted for by an exponential decay term applied directly to the particle concentration. The second and third types of reactions are incorporated through a retardation factor, which is a function of concentration for nonlinear cases. The model is evaluated and verified by comparison with analytical solutions for linear sorption and decay, and by comparison with other numerical solutions for nonlinear sorption and ion exchange.

Water-Resources Investigations Report↗

USGS1996

Applications of inductively coupled plasma-mass spectrometry in environmental radiochemistry

The state of the art in ICP-MS is now such that there are few discernible differences between radiochemical and mass spectrometric determinations of longlived radionuclides. Indeed, ICP-MS may provide better (more sensitive) data for many radionuclides, depending upon how one wishes to define "long-lived." In lowlevel determinations, sample preparation remains an important part of the analytical procedure, even with ICP-MS, but the speed and isotopic selectivity of the mass spectrometer appear to offer distinct procedural advantages over radiochemical techniques. Therefore, "radioanalytical" ICP-MS applications should continue to grow, especially in the area of radiation protection, but further research (on efficient sample introduction, for example) and method development may be required to get ICP-MS "off the ground" in the geochemical research areas that have traditionally been supported by radiochemistry.

Spectroscopy↗

USGS2026

In-situ geochronology using LA-ICP-MS/MS: Application of the Lu-Hf system in carbonate, apatite and fluorite

Geochronology is a fundamental tool for reconstructing earth history and constraining the timing of ore deposit formation. Traditionally, U-rich minerals like zircon, titanite, monazite and apatite have been analysed to determine the timing of mineralization and alteration events. However, not all deposits or alteration assemblages contain these minerals, and the U-Pb system can be disturbed due to open system behaviour. We present a methodology for obtaining in-situ Lu-Hf dates from various minerals to demonstrate the potential for dating ore deposits that lack U-rich minerals. Carbonate, apatite and fluorite minerals from different tectonic settings and geological environments were analysed. We acquired Lu-Hf and REE (rare earth element) data from carbonate minerals from a carbonatite orebody and dike samples from the Mountain Pass REE carbonatite deposit in California, USA. We also tested a ‘double-dating’ method, where U-Th-Pb dates and Lu-Hf dates were obtained from the same analysis of apatite from rocks in the Michigan’s Great Lakes Tectonic Zone. Preliminary results for Lu-Hf dating of fluorite from carbonatite rocks in the Lemitar Mountains of New Mexico are also included. The analytical methodology shows promising results in each of these cases where there is sufficient parent Lu and U and measurable daughter Hf and Pb respectively.

Conference Paper↗

USGS1999

Poisoning of wild birds from exposure to anticholinesterase compounds and lead: diagnostic methods and selected cases

Organophosphorus and carbamate compounds have largely replaced chlorinated hydrocarbons for pesticidal use in the United States, and many cases of poisoning resulting from exposure to these anticholinesterase agents have occurred in free-living birds. Although lead shot has been prohibited for waterfowl hunting throughout the United States since 1991, lead poisoning from the ingestion of spent lead shot is still occasionally seen in wild birds, and lead poisoning from the ingestion of fishing sinkers is an emerging issue of concern. A thorough history, a complete necropsy evaluation, and appropriate laboratory analysis of tissues are required to diagnose toxicoses in wild birds, including those caused by anticholinesterase compounds and lead. The interpretation of brain cholinesterase (ChE) activity results depends on the methods of analysis and comparison with expected normal enzyme activities in brain tissue from the same species. Although lead residues in tissues vary among species, many lead poisoned birds have tissue residues that are much higher than the lower threshold commonly accepted for a diagnosis of lead poisoning. We review histories, necropsy findings, and analytical methodologies and results for selected anticholinesterase and lead poisoning cases diagnosed in wild raptors, waterfowl, and loons.

Seminars in Avian and Exotic Pet Medicine↗

USGS2002

Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry

The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe the relationship of the absorption of 6Li and 7Li lamp radiation is proposed as a means of calculating isotopic composition that is independent of total lithium concentration.

Analytical Chemistry↗

USGS2002

Fluorometric study of the magnesium—Bissalicylidene-ethylenediamine aystem

Magnesium ions combine with bissalicylidene-ethylenediamine in slightly alkaline N,N′-dimethylformamide to form a highly fluorescent complex which serves for the determination of trace amounts of magnesium. The yellow complex fluoresces blue when irradiated with ultraviolet light. The chelate shows maximum fluorescence excitation at 355 mμ and has a fluorescence emission maximum at 439 mμ. A complex having a metal to ligand ratio of 1 to 1 is formed. The method is sensitive to 7 × 10 −6 μmole of magnesium per ml. The analysis of Bureau of Standards samples with the reagent showed excellent correlation between the fluorometric and spectrophotometric procedures

Analytical Chemistry↗

USGS2020

Improved selenium recovery from tissue with modified sample decomposition

The present paper describes a simple modification of a recently reported decomposition method for determination of selenium in biological tissue by hydride generation atomic absorption. The modified method yielded slightly higher selenium recoveries (3-4%) for selected reference tissues and fish tissue spiked with selenomethionine. Radiotracer experiments indicated that the addition of a small volume of hydrochloric acid to the wet digestate mixture reduced slight losses of selenium as the sample initially went to dryness before ashing. With the modified method, selenium spiked as selenomethionine behaved more like the selenium in reference tissues than did the inorganic spike forms when this digestion modification was used.

Journal of the Association of Official Analytical ↗

USGS2004

A visual basic program to generate sediment grain-size statistics and to extrapolate particle distributions

Measures that describe and summarize sediment grain-size distributions are important to geologists because of the large amount of information contained in textural data sets. Statistical methods are usually employed to simplify the necessary comparisons among samples and quantify the observed differences. The two statistical methods most commonly used by sedimentologists to describe particle distributions are mathematical moments (Krumbein and Pettijohn, 1938) and inclusive graphics (Folk, 1974). The choice of which of these statistical measures to use is typically governed by the amount of data available (Royse, 1970). If the entire distribution is known, the method of moments may be used; if the next to last accumulated percent is greater than 95, inclusive graphics statistics can be generated. Unfortunately, earlier programs designed to describe sediment grain-size distributions statistically do not run in a Windows environment, do not allow extrapolation of the distribution's tails, or do not generate both moment and graphic statistics (Kane and Hubert, 1963; Collias et al., 1963; Schlee and Webster, 1967; Poppe et al., 2000) 1 . Owing to analytical limitations, electro-resistance multichannel particle-size analyzers, such as Coulter Counters, commonly truncate the tails of the fine-fraction part of grain-size distributions. These devices do not detect fine clay in the 0.6–0.1 μm range (part of the 11-phi and all of the 12-phi and 13-phi fractions). Although size analyses performed down to 0.6 μm microns are adequate for most freshwater and near shore marine sediments, samples from many deeper water marine environments (e.g. rise and abyssal plain) may contain significant material in the fine clay fraction, and these analyses benefit from extrapolation. The program (GSSTAT) described herein generates statistics to characterize sediment grain-size distributions and can extrapolate the fine-grained end of the particle distribution. It is written in Microsoft Visual Basic 6.0 and provides a window to facilitate program execution. The input for the sediment fractions is weight percentages in whole-phi notation (Krumbein, 1934; Inman, 1952), and the program permits the user to select output in either method of moments or inclusive graphics statistics (Fig. 1). Users select options primarily with mouse-click events, or through interactive dialogue boxes.

Computers & Geosciences↗

USGS2010

A rapid method for the measurement of sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), and Halon 1211 (CF2ClBr) in hydrologic tracer studies

A rapid headspace method for the simultaneous laboratory determination of intentionally introduced hydrologic tracers, sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), Halon 1211 (CF2ClBr), and other halocarbons in water and gases is described. The high sensitivity of the procedure allows for introduction of minimal tracer mass (a few grams) into hydrologic systems with a large dynamic range of analytical detection (dilutions to 1:108). Analysis times by gas chromatography with electron capture detector are less than 1 min for SF6; about 2 min for SF6 and SF5CF3; and 4 min for SF6, SF5CF3, and Halon 1211. Many samples can be rapidly collected, preserved in stoppered septum bottles, and analyzed at a later time in the laboratory. Examples are provided showing the effectiveness of the gas tracer test studies in varied hydrogeological settings.

Geochemistry, Geophysics, Geosystems↗

USGS1979

Methods for determination of inorganic substances in water and fluvial sediments

Chapter Al of the manual contains methods used by the U.S. Geological Survey to collect, preserve, and analyze water samples for their content of dissolved minerals and gases. Among the topics discussed are selection of sampling sites, frequency of sampling, sampling equipment, sample preservation, laboratory equipment and instrumental techniques, accuracy and precision of analysis, and reporting of results. Seventy-six analytical procedures are given for determining 55 water properties. Listed below are the water properties for which analytical pro- cedures are given, and the principal procedure for the determination of each.

Techniques of Water-Resources Investigations↗

USGS2002

Semiquantitative spectrographic method for analysis of minerals, rocks, and ores

The quantity and complex nature of materials received for analysis in the spectrographic laboratories of the U. S. Geological Survey have emphasized the need for a spectrographic method to determine a maximum number of elements in a limited time with a reasonable degree of accuracy. The semiquantitative method described determines 68 elements in one arcing of a 10-mg. sample. The method has been used to complete 245,000 determinations during a 3-year period. Each determination is reported as a concentration range or bracket (0.001 to 0.01, 0.01 to 0.1%, etc.). A chemical check of 500 such determinations showed 92% in agreement; the remaining 8% agreed to within one bracket. The method requires a minimum of sample handling, thus reducing the chances of contamination, detects low concentrations of elements, and is rapid. Analyses have been completed on a wide variety of materials.

Analytical Chemistry↗

USGS2002

Determination of boron in silicates after ion exchange separation

Existing methods for the determination of boron in silicates are not entirely satisfactory. Separation as the methyl ester is lengthy and frequently erratic. An accurate and rapid method applicable to glass, mineral, ore, and water samples uses ion exchange to remove interfering cations, and boron is determined titrimetrically in the presence of mannitol, using a pH meter to indicate the end point.

Analytical Chemistry↗

USGS1964

Copper determinations on samples of alluvium and caliche from the rocky Range, Beaver County, Utah

A study of the distribution of copper in transported alluvium on a pediment of the Rocky Range, Beaver County, Utah, undertaken to determine whether known copper deposits in bedrock concealed by alluvium could be detected by geochemical methods, was reported in Geological Survey Research 1960 ( Erickson, R.L., and Marrenzino, A.P., 1960, Geochemical prosecting for copper in the Rocky Range, Beaver County, Utah; U.S. Geol. Survey Prof. Paper 400-B, p. B98-E101). The attached map and table supplement that paper by giving the locations at which the samples were collected and the analytical determinations of copper in the samples.

Utah↗

USGS2002

Nephelometric determination of fluorine

Fluorine in minerals may be determined with the nephelometer to about 1 per cent of the fluorine. The determination is made on an aliquot of the sodium chloride solution of the fluorine, obtained by the Berzelius method of extraction. The fluorine is precipitated as colloidal calcium fluoride in alcoholic solution, gelatin serving as a protective colloid. Arsenates, sulfates, and phosphates, which interfere with the determination, must be removed.

Industrial And Engineering Chemistry Analytical Ed↗

USGS1986

Inductively coupled plasma atomic fluorescence spectrometric determination of cadmium, copper, iron, lead, manganese and zinc

An inductively coupled plasma atomic fluorescence spectrometric method is described for the determination of six elements in a variety of geological materials. Sixteen reference materials are analysed by this technique to demonstrate its use in geochemical exploration. Samples are decomposed with nitric, hydrofluoric and hydrochloric acids, and the residue dissolved in hydrochloric acid and diluted to volume. The elements are determined in two groups based on compatibility of instrument operating conditions and consideration of crustal abundance levels. Cadmium, Cu, Pb and Zn are determined as a group in the 50-ml sample solution under one set of instrument conditions with the use of scatter correction. Limitations of the scatter correction technique used with the fluorescence instrument are discussed. Iron and Mn are determined together using another set of instrumental conditions on a 1-50 dilution of the sample solution without the use of scatter correction. The ranges of concentration (??g g-1) of these elements in the sample that can be determined are: Cd, 0.3-500; Cu, 0.4-500; Fe, 85-250 000; Mn, 45-100 000; Pb, 5-10 000; and Zn, 0.4-300. The precision of the method is usually less than 5% relative standard deviation (RSD) over a wide concentration range and acceptable accuracy is shown by the agreement between values obtained and those recommended for the reference materials.

Journal of Analytical Atomic Spectrometry↗

USGS2022

U.S. Geological Survey Core Research Center: A gateway to subsurface discovery for geoscience research

The U.S. Geological Survey (USGS) operates the Core Research Center (CRC) in Denver, Colorado, USA, a public access repository of rock cores from over 9800 wells and drill cuttings from over 53 000 wells, primarily from states in or adjacent to the Rocky Mountain Region. Annually, approximately 1400 visitors use the collection for traditional and innovative research. The CRC has an online, searchable database which includes downloadable core photos, analytical data, and thin-section images. When visitors sample for analyses, the results must be returned to the CRC for public dissemination providing immediate, free access to users while sparing the finite, irreplaceable collection from redundant testing. A representative quantity of every core depth is preserved in perpetuity. Studies on CRC materials, paired with new extraction methods, have unlocked new productive deposits. Materials drilled and curated decades ago remain in high demand while materials receiving little attention today may be crucial for future research. The collection provides immediate, inexpensive access to subsurface materials at a fraction of the cost of new drilling, sparing money, time and environmental impacts.

Geological Society, London, Special Publications↗

USGS1998

FEMFLOW3D; a finite-element program for the simulation of three-dimensional aquifers; version 1.0

This document describes a computer program that simulates three-dimensional ground- water systems using the finite-element method. The program was developed to simulate regional ground-water systems, but it can be applied to small-scale problems as well. This program can be used to simulate both confined and water-table aquifers. The program simulates a linearized three-dimensional free-surface ground-water system with a fixed grid. FEMFLOW3D is applicable to the simulation of various free-surface ground-water systems for which the change in aquifer thickness is small relative to the overall aquifer thickness. The finite-element method provides flexibility in the design of a geometric grid that represents the physical dimensions of an aquifer system. For example, features that can be well represented with a finite-element grid include irregular, random geographic and geologic features; irregular boundaries; and increased detail within localized areas of particular interest within the study area. The structure of the computer program consists of a main program, which serves as a simple driver, and a set of subroutines in which the calculations are performed. The background, mathematical basis, structure, and inputs for each of the subroutines are described in the document where applicable. Each subroutine generally handles (1) a part of the mathematical calculations related to the finite-element method, (2) a specific feature of the hydrologic system, or (3) special features related to the management input or output data. Hydrologic features that can be represented with the program include stream-aquifer interactions, phreatophytic evapotranspiration, highly permeable fault zones, land subsidence, and land-aquifer interactions associated with land-use activities. The program can also represent the primary features associated with complex irrigation systems, such as irrigated agriculture, and can calculate the ground-water recharge that results from these activities. Three boundary conditions, including specified-head boundaries, specified-flux boundaries, and variable-flux boundaries, can be represented with the program. The program also provides a method for identifying aquifer and river-bed parameters that can be used in the calibration of models. This document also includes model validation, source code, and example input and output files. Model validation was performed using four test problems. For each test problem, the results of a model simulation with FEMFLOW3D were compared with either an analytic solution or the results of an independent numerical approach. The source code, written in the ANSI x3.9-1978 FORTRAN standard, and the complete input and output of an example problem are listed in the appendixes.

Open-File Report↗

USGS2017

Detection of microcystin and other cyanotoxins in lakes at Isle Royale National Park, Pictured Rocks National Lakeshore, and Sleeping Bear Dunes National Lakeshore, northern Michigan, 2012–13

Although cyanotoxins released during algal blooms have become an increasing concern in surface waters across the United States, the presence of cyanotoxins in northern Michigan lakes had not been evaluated in detail. The U.S. Geological Survey and National Park Service (NPS) led a 2-year study (2012 and 2013) to determine the presence of microcystin and other algal toxins in several inland lakes at Isle Royale National Park (hereafter referred to as ISRO, Pictured Rocks National Lakeshore (hereafter referred to as PIRO), and Sleeping Bear Dunes National Lakeshore (hereafter referred to as SLBE). Samples also were collected at four sites in Lake Michigan within the SLBE. The two analytical techniques used in the study were enzyme-linked immunosorbent assays (ELISA) for microcystin, cylindrospermopsin, and saxitoxin; and liquid chromatography/tandem mass spectrometry (LC/MS/MS) for a larger suite of algal toxins. Neither cylindrospermopsin nor saxitoxin were detected in the 211 samples. Microcystin was detected in 31 percent of samples (65 of 211 samples) analyzed by the ELISA method, but no sample results exceeded the World Health Organization recreational health advisory standard for microcystin (10 micrograms per liter [µg/L]). However, about 10 percent of the samples (21 of 211 samples) that were collected from PIRO and SLBE and were analyzed by ELISA for microcystin had concentrations greater than the U.S. Environmental Protection Agency (EPA) drinking water 10-day health advisory of 0.3 µg/L for children preschool age and younger (less than 6-years old). One sample collected in 2012 from SLBE exceeded the EPA drinking water 10-day health advisory of 1.6 µg/L for school-age children through adults (6-years old and older). In 2012, the highest concentration of 2.7 µg/L was detected in Florence Lake within SLBE. Many visitors enjoy recreation in or on the water and camp in the backcountry at these national parks where the most common source of drinking water is filtered surface water. Approximately 18 percent of the samples (39 of 211 samples) were analyzed by LC/MS/MS to confirm the ELISA results and to evaluate the samples for a larger suite of algal toxins. In general, the microcystin results between the ELISA and LC/MS/MS methods were similar; although, the ELISA results tended to be slightly higher than the summation of LC/MS/MS microcystin congeners. The slightly higher ELISA results might be because the ELISA microcystin method is reactive with the ADDA functional group common to all microcystins, and because not all microcystin congeners are included in the LC/MS/MS method. The LC/MS/MS method indicated that the congener microcystin-LR was the most frequently detected, followed by microcystin-WR and microcystin-YR. Sixteen of the lakes included in this study also were monitored by the NPS for nutrients. Total phosphorus (TP) concentrations were, on average, highest at the ISRO lakes, whereas total nitrogen (TN) concentrations were highest at SLBE. The average annual TN:TP ratios for the 16 lakes within the national park and national lakeshores ranged from ratios of 20 to 89. Overall, results indicated a slight increase in percentage of microcystin detections with an increase in the TN:TP ratio (R-squared 0.269 and 0.340, respectively [2012 and 2013 combined dataset] derived from linear regression). This study also indicated that even in the absence of visible algal blooms, microcystin may be present. Most microcystin concentrations did not exceed the EPA’s 10-day health advisory drinking-water benchmark. In general, these results provide a useful baseline with which to evaluate potential future changes in algal toxin concentrations.

Michigan↗