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At least 793 records · Page 44Linked to original sources
USGS1994

Methods of analysis and quality-assurance practices of the U.S. Geological Survey organic laboratory, Sacramento, California: Determination of pesticides in water by solid-phase extraction and capillary-column gas chromatography/mass spectrometry

Analytical method and quality-assurance practices were developed for a study of the fate and transport of pesticides in the Sacramento-San Joaquin Delta and the Sacramento and San Joaquin River. Water samples were filtered to remove suspended parti- culate matter and pumped through C-8 solid-phase extraction cartridges to extract the pesticides. The cartridges were dried with carbon dioxide, and the pesticides were eluted with three 2-milliliter aliquots of hexane:diethyl ether (1:1). The eluants were analyzed using capillary-column gas chromatography/mass spectrometry in full-scan mode. Method detection limits for analytes determined per 1,500-milliliter samples ranged from 0.006 to 0.047 microgram per liter. Recoveries ranged from 47 to 89 percent for 12 pesticides in organic-free, Sacramento River and San Joaquin River water samples fortified at 0.05 and 0.26 microgram per liter. The method was modified to improve the pesticide recovery by reducing the sample volume to 1,000 milliliters. Internal standards were added to improve quantitative precision and accuracy. The analysis also was expanded to include a total of 21 pesticides. The method detection limits for 1,000-milliliter samples ranged from 0.022 to 0.129 microgram per liter. Recoveries ranged from 38 to 128 percent for 21 pesticides in organic-free, Sacramento River and San Joaquin River water samples fortified at 0.10 and 0.75 microgram per liter.

California↗
USGS1995

Ground-water data for the Suck Creek area of Walden Ridge, southern Cumberland Plateau, Marion County, Tennessee

An investigation was made of the ground-water resources of the Suck Creek area, Marion County, Tennessee, 1990-91. Suck Creek is located on the Walden Ridge section of the Cumberland Plateau, and is about 16 miles northwest of Chattanooga. Eight wells were drilled into bedrock of Pennsylvania age. Drilling sites were chosen at or near fracture traces. Yields of the eight wells ranged from less than 1 to as much as 80 gallons of water per minute. Three wells had yields of 50 gallons per minute or more; two of these had estimated yields of 75 to 80 gallons per minute. These three wells produced water from a well- developed fracture within the Sewanee Conglomerate. Specific capacities for these three wells were 1.1, 1.3, 2.2 gallons per minute per foot of drawdown. Samples of water from six test wells and three domestic wells were analyzed for major inorganic constituents, nurients, major metals, trace elements, and bacteria. In addition, water samples from two of the test wells were analyzed for volatile organic compounds and scanned for the presence of semi-volatile organic compounds. Iron exceeded 300 micrograms per liter in five of the nine samples, and manganese exceeded 50 micrograms per liter in seven of the nine water samples. Toluene, a volatile organic compound, was detected in a concentration slightly above the reporting level; no other volatile organic compounds were detected.

Tennessee↗
USGS1995

Isopachs of Quaternary deposits, Fremont 1- by 2- degree Quadrangle and part of Omaha Quadrangle, Nebraska, digitized from a published 1:250,000-scale geologic map

A geologic map showing the isopachs of Quaternary deposits in the Fremont and part of the Omaha, Nebraska, 1- by 2-degree quadrangles was published at a scale of 1:250,000 in 1975 (Burchett and others, 1975). This report describes the conversion of Quaternary thickness data into a digital geographic data set. A film separation of the published isopachs was scan-digitized and processed to produce digital geographic data. Geographic feature attributes and data-set documentation also are included in the digital data set. The digital data set are formatted for distribution with accordance with the Spatial Data Transfer Standard approved by the U.S. National Institute of Standards and Technology.

Open-File Report↗
USGS1995

Water-quality, discharge, and biologic data for streams and springs in the Highland Rim Escarpment of southeastern Bedford County, Tennessee

From November 1994 through April 1995, streams and springs in 9 drainage basins were observed and sampled at 176 sites to obtain information on environmental quality near the Quail Hollow landfill, Bedford County, Tennessee. Reconnaissance data were collected to establish a regional pattern. Water samples from 26 seepage sites were analyzed to determine water-quality conditions. During the reconnaissance, conductivity ranged regionally from 17 to 617 microsiemens per centimeter. The greatest biologic diversity was in Bennett Branch, followed by Daniel Hollow, Prince, Powell and Renegar, County Line, and Anthony Branches, Hurricane Creek, and Anderton Branch, respectively. In general, conductivity was less than 50 microsiemens per centimeter at and upstream of the Chattanooga Shale but increased downstream to between 200 and 300 microsiemens per centimeter. Of the constituents and properties analyzed, only pH and four metals at six sites had values that were not within the limits set by the State of Tennessee for drinking water. Chloride and dissolved manganese concentrations were highest for a spring and a seep adjacent to the landfill. Scans indicated the presence of about 37 unidentified organic compounds at these same two sites.

Tennessee↗
USGS1996

MUDMASTER: A Program for Calculating Crystalline Size Distributions and Strain from the Shapes of X-Ray Diffraction Peaks

Particle size may strongly influence the physical and chemical properties of a substance (e.g. its rheology, surface area, cation exchange capacity, solubility, etc.), and its measurement in rocks may yield geological information about ancient environments (sediment provenance, degree of metamorphism, degree of weathering, current directions, distance to shore, etc.). Therefore mineralogists, geologists, chemists, soil scientists, and others who deal with clay-size material would like to have a convenient method for measuring particle size distributions. Nano-size crystals generally are too fine to be measured by light microscopy. Laser scattering methods give only average particle sizes; therefore particle size can not be measured in a particular crystallographic direction. Also, the particles measured by laser techniques may be composed of several different minerals, and may be agglomerations of individual crystals. Measurement by electron and atomic force microscopy is tedious, expensive, and time consuming. It is difficult to measure more than a few hundred particles per sample by these methods. This many measurements, often taking several days of intensive effort, may yield an accurate mean size for a sample, but may be too few to determine an accurate distribution of sizes. Measurement of size distributions by X-ray diffraction (XRD) solves these shortcomings. An X-ray scan of a sample occurs automatically, taking a few minutes to a few hours. The resulting XRD peaks average diffraction effects from billions of individual nano-size crystals. The size that is measured by XRD may be related to the size of the individual crystals of the mineral in the sample, rather than to the size of particles formed from the agglomeration of these crystals. Therefore one can determine the size of a particular mineral in a mixture of minerals, and the sizes in a particular crystallographic direction of that mineral.

Open-File Report↗
USGS1997

Digital data set that describe aquifer characteristics of the Antlers aquifer in southeastern Oklahoma

The data sets in this report include digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Antlers aquifer in southeastern Oklahoma. The Early Cretaceous-age Antlers Sandstone is an important source of water in an area that underlies about 4,400-square miles of all or part of Atoka, Bryan, Carter, Choctaw, Johnston, Love, Marshall, McCurtain, and Pushmataha Counties. The Antlers aquifer consists of sand, clay, conglomerate, and limestone in the outcrop area. The upper part of the Antlers aquifer consists of beds of sand, poorly cemented sandstone, sandy shale, silt, and clay. The Antlers aquifer is unconfined where it outcrops in an area of about 1,800-square miles (Morton, 1992). The recharge, hydraulic conductivity, and aquifer boundaries data sets include the outcrop area of the Antlers Sandstone in Oklahoma and areas where the Antlers is overlain by alluvial and terrace deposits and a few small thin outcrops of the Goodland Limestone. Most of the lines in the data sets are from the digital data of the surficial geology of the Antlers Sandstone from Cederstrand (1996a, 1996b) except where the Antlers aquifer is overlain by alluvial and terrace deposits near streams and rivers. Morton (1992) interpolated the Antlers aquifer boundaries under the alluvial and terrace deposits where streams cross the aquifer outcrop. Aquifer boundary lines for areas where the aquifer is overlain by alluvial and terrace deposits were digitized and are similar to the aquifer boundaries shown in Morton (1992). A few polygons in this data set represent small and thin outcrops of the Goodland Limestone overlying the Antlers aquifer. The Antlers aquifer in Texas (Morton, 1992) is not included in this data set. The maps from which this data set was derived were scanned or digitized from maps published at a scale of 1:250,000. Hydraulic conductivity and recharge values were used as input to the ground-water model report for the Antlers aquifer by Morton (1992). The water-level elevation contours were digitized from a mylar map at a scale of 1:250,000 that was used to prepare the final map that was published as plate 1, map A, "Observed potentiometric surface, 1970, Antlers aquifer" at a scale of 1:500,000 in Morton (1992). Morton (1992) used water levels measured in wells in 1970 to construct the map. The water-level elevation contours for the Antlers aquifer in Texas (Morton, 1992) are not included in this data set. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. The hydraulic conductivity and recharge are closely interrelated. As long as these two model inputs are in balance the model has a small mean residual; it represents the natural system numerically. If the hydraulic conductivity is accurately known, the model can be used to accurately determine recharge. Likewise, if the hydraulic conductivity is poorly known, then the recharge will be poorly determined. Therefore, values of hydraulic conductivity and recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data. In most aquifers, hydraulic conductivity measurements made in wells or in cores will range over several orders of magnitude, even over short horizontal and vertical distances. Hydraulic conductivity values derived from ground-water flow models represent areal generalizations and do not reflect the large local variance in well or core measurements. Recharge probably varies considerably over the local area, and model recharge is at best an average over an area at least as large as the model grid (and probably much larger than a single cell). Compilation of the data sets was funded under a cooperative Joint Funding Agreement between the U.S. Geological Survey and the State of Oklahoma, Office of the Secretary of Environment.

Oklahoma↗
USGS1996

Determination of atrazine and its major degradation products in soil pore water by solid-phase extraction, chemical derivatization, and gas chromatography/mass spectrometry

This report describes a method for the determination of atrazine, desethylatrazine, deisopropylatrazine, didealkylatrazine, and hydroxyatrazine from soil pore waters by use of solid-phase extractionfollowed by chemical derivatization and gas chromatography/mass spectrometry. The analytes are isolated from the pore-water matrix byextraction onto a graphitized carbon-black cartridge. The cartridge is dried under vacuum, and adsorbed analytes are removed by elution with ethyl acetate followed by dichloromethane/methanol (7:3, volume/volume). Water is removed from the ethyl acetate fraction on an anhydrous sodium sulfate column. The combined fractions are solvent exchanged into acetonitrile, evaporated by use of a nitrogen stream, and derivatized by use of N- methyl-N-(tert-butyldimethylsilyl)- trifluoroacetamide. The derivatized extracts are analyzed by capillary-column gaschromatography/electron-impact mass spectrometry in the scan mode. Estimated method detection limits range from 0.03 to 0.07 micrograms per liter. The mean recoveries of all analytes and surrogates determined at 0.74 to 0.82 micrograms per liter in reagent water in soil pore water were 94 percent and 98 percent, respectively. The mean recoveries of all analytes and surrogates determined at 7.4 to 8.2 micrograms per liter in reagent water and in soil pore water were 96 percent and 97 percent,respectively. Recoveries were 90 percent or higher, regardless of analyte concentration or matrix composition, for all compounds excepthydroxyatrazine, whose recoveries were slightly lower (77 percent) at the low concentration.

Open-File Report↗
USGS1997

Determining concentrations of 2-bromoallyl alcohol and dibromopropene in ground water using quantitative methods

A method for determining levels of 2-bromoallyl alcohol and 2,3-dibromopropene from ground-water samples using liquid/liquid extraction followed by gas chromatography/mass spectrometry is described. Analytes were extracted from the water using three aliquots of dichloromethane. The aliquots were combined and reduced in volume by rotary evaporation followed by evaporation using a nitrogen stream. The extracts were analyzed by capillary-column gas chromatography/mass spectrometry in the full-scan mode. Estimated method detection limits were 30 nanograms per liter for 2-bromoallyl alcohol and 10 nanograms per liter for 2,3-dibromopropene. Recoveries were determined by spiking three matrices at two concentration levels (0.540 and 5.40 micrograms per liter for 2-bromoallyl alcohol; and 0.534 and 5.34micro-grams per liter for dibromopropene). For seven replicates of each matrix at the high concentration level, the mean percent recoveries ranged from 43.9 to 64.9 percent for 2-bromoallyl alcohol, and from 87.5 to 99.3 percent for dibromopropene. At the low concentration level, the mean percent recoveries ranged from 43.8 to 95.2 percent for 2-bromoallyl alcohol, and from 71.3 to 84.9 percent for dibromopropene.

Open-File Report↗
USGS1998

Descriptions of selected digital spatial data for Ravenna Army Ammunition Plant, Ohio

Digital spatial data of Ravenna Army Ammunition Plant (RVAAP), in northeastern Ohio, were compiled or generated from existing maps for U.S. Army Industrial Operations Command. The data are in the Ohio north state-plane coordinate system (North American Datum of 1983) in an ARC/INFO geographic information system format. The data comprise 15 layers, which include boundaries, topography, and natural and cultural features. An additional layer comprises scanned and rectified aerial photographs of RVAAP.

Open-File Report↗
USGS1998

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of 86 volatile organic compounds in water by gas chromatography/mass spectrometry, including detections less than reporting limits

This report presents precision and accuracy data for volatile organic compounds (VOCs) in the nanogram-per-liter range, including aromatic hydrocarbons, reformulated fuel components, and halogenated hydrocarbons using purge and trap capillary-column gas chromatography/mass spectrometry. One-hundred-four VOCs were initially tested. Of these, 86 are suitable for determination by this method. Selected data are provided for the 18 VOCs that were not included. This method also allows for the reporting of semiquantitative results for tentatively identified VOCs not included in the list of method compounds. Method detection limits, method performance data, preservation study results, and blank results are presented. The authors describe a procedure for reporting low-concentration detections at less than the reporting limit. The nondetection value (NDV) is introduced as a statistically defined reporting limit designed to limit false positives and false negatives to less than 1 percent. Nondetections of method compounds are reported as ?less than NDV.? Positive detections measured at less than NDV are reported as estimated concentrations to alert the data user to decreased confidence in accurate quantitation. Instructions are provided for analysts to report data at less than the reporting limits. This method can support the use of either method reporting limits that censor detections at lower concentrations or the use of NDVs as reporting limits. The data-reporting strategy for providing analytical results at less than the reporting limit is a result of the increased need to identify the presence or absence of environmental contaminants in water samples at increasingly lower concentrations. Long-term method detection limits (LTMDLs) for 86 selected compounds range from 0.013 to 2.452 micrograms per liter (?g/L) and differ from standard method detection limits (MDLs) in that the LTMDLs include the long-term variance of multiple instruments, multiple operators, and multiple calibrations over a longer time. For these reasons, LTMDLs are expected to be slightly higher than standard MDLs. Recoveries for all of the VOCs tested ranged from 36 (tert-butyl formate) to 155 percent (pentachlorobenzene). The majority of the compounds ranged from 85 to 115 percent recovery and had less than 5 percent relative standard deviation for concentrations spiked between 1 to 500 ?g/L in volatile blank-, surface-, and ground-water samples. Recoveries of 60 set spikes at low concentrations ranged from 70 to 114 percent (1,2,3- trimethylbenzene and acetone). Recovery data were collected over 6 months with multiple instruments, operators, and calibrations. In this method, volatile organic compounds are extracted from a water sample by actively purging with helium. The VOCs are collected onto a sorbent trap, thermally desorbed, separated by a Megabore gas chromatographic capillary column, and finally determined by a full-scan quadrupole mass spectrometer. Compound identification is confirmed by the gas chromatographic retention time and by the resultant mass spectrum, typically identified by three unique ions. An unknown compound detected in a sample can be tentatively identified by comparing the unknown mass spectrum to reference spectra in the mass-spectra computer-data system library compiled by the National Institute of Standards and Technology.

Open-File Report↗
USGS1998

Digital Geologic Map of the Rosalia 1:100,000 Quadrangle, Washington and Idaho: A Digital Database for the 1990 S.Z. Waggoner Map

The geologic map of the Rosalia 1:100,000-scale quadrangle was compiled in 1990 by S.Z. Waggoner of the Washington state Division of Geology and Earth Resources. This data was entered into a geographic information system (GIS) as part of a larger effort to create regional digital geology for the Pacific Northwest. The intent was to provide a digital geospatial database for a previously published black and white paper geologic map. This database can be queried in many ways to produce a variety of geologic maps. Digital base map data files are not included: they may be obtained from a variety of commercial and government sources. This database is not meant to be used or displayed at any scale larger than 1:100,000 (e.g., 1:62,500 or 1:24,000) as it has been somewhat generalized to fit the 1:100,000 scale map. The map area is located in eastern Washington and extends across the state border into western Idaho. This open-file report describes the methods used to convert the geologic map data into a digital format, documents the file structures, and explains how to download the digital files from the U.S. Geological Survey public access World Wide Web site on the Internet. We wish to thank J. Eric Schuster of the Washington Division of Geology and Earth Resources for providing the original stable-base mylar and the funding for it to be scanned. We also thank Dick Blank and Barry Moring of the U.S. Geological Survey for reviewing the manuscript and digital files, respectively.

Open-File Report↗
USGS1998

GLORIA sidescan sonar field data and navigation data collected off Puerto Rico in 1985 and the eastern United States in 1987

This CD-ROM contains copies of the navigation and field sidescan sonar data collected within the Exclusive Economic Zone (EEZ) surrounding Puerto Rico and off the eastern United States during cruises aboard the R/V FARNELLA. The survey of the Puerto Rico EEZ was completed during one cruise between 4 November and 3 December, 1985. The survey of the EEZ off the eastern United States was completed during five cruises between 2 February and 30 May, 1987. The data were collected as part of the USGS EEZ-SCAN program which was a cooperative mapping program between the US Geological Survey and the Institute of Oceanographic Sciences of the UK. The survey areas included the entire US EEZ of Puerto Rico and the US Virgin Islands as well as of the eastern United States from the Canadian international boundary at Georges Bank to the Bahamian international boundary east of Florida. GLORIA imagery was collected seaward of approximately 400 m water depth.

Open-File Report↗
USGS1999

Turbidite pathways in Cascadia Basin and Tufts abyssal plain, Part A, Astoria Channel, Blanco Valley, and Gorda Basin

This open-file report was prepared in support of the USGS Earthquake Hazards of Cascadia Project. The primary objective of this phase of the project is to determine recurrence intervals of turbidites in Cascadia basin-floor channel systems and evaluate implications of this event record for the paleoseismic history of the Cascadia subduction zone. The purpose of this study is to determine whether the canyon/channel systems themselves are blocked or deformed in such a way that the downstream turbidite stratigraphy might be biased. To accomplish this investigation approximately 7500 kilometers of pre-existing 3.5 KHz seismic data were evaluated to determine the direction and extent of the Astoria Channel/pathway system, which originates at the base of the Astoria Fan. Additionally, distribution and thickness of turbidite sediment sequences were determined along each identified pathway. Bathymetery and distance were used to determine gradients along the main pathway axis and for each of the secondary pathways that feed into it. Channel pathways were identified on the basis of channel phyisiography, where visible at the seafloor, subbottom channel configuration, and acoustic packets of sediments that might represent turbidite deposits. A principal result of this study is that the Astoria Channel/pathway extends continuously from the base of the Astoria Fan southward along the base of the continental slope through the Blanco Valley, then heads southwestward through the Gorda Basin and into the region of the Escanaba Trough. Additionally it was determined that the Astoria Channel is filled and basically buried for it's full length south of 44 degrees latitude. The 44 North Slump, as defined by Goldfinger (1999, see Map 3 ref.), may have been instrumental in blocking the pathway and thus contributed to the filling of the channel/pathway. Sheets 1 and 2 show the Astoria and secondary turbidite pathways highlighted in blue. Ship survey tracklines are shown for the area studied; they are time and date coded, and color keyed to each ship ID data base listed at the bottom of each sheet. The first letter in the cruise ID is an abbreviation letter for the ship name, the following numbers represent the consecutive cruise number of that year, followed by the year number. The letters at the end of the ID represent the survey area, ie. NC- northern California, NP- north Pacific. Locations of selected sample seismic sections illustrated on sheets 3-5 also are shown. Scales for each of the sheets are the same as for sheets 3-5, which allows for overlaying of track data onto the interpretations shown on Maps A-C. Sheets 3 (MAP A), 4 (MAP B), and 5 (MAP C) show channel pathway location, bathymetric depth based on the USGS COW data base (Ca/Or/Wa), pathway morphology, and thickness of turbidite sediment fill at various locations. The interpreted turbidite sediments are color highlighted on the selected seismic sections to differentiate them from the typical deep sea sediments below and to the side of the turbidite pathways. Thickness of sediment fill, in meters, is shown along major pathways in white circular highlights. The data and interpretations rest on a background of USGS GLORIA side scan sonar imagery (1984) to illustrate the relationship of pathway position to sub sea features. Channel distance points are plotted along channel centerlines at 20,000 m intervals. These points begin at the start of each interpreted channel pathway. A bathymetric depth was assigned to each distance point. These data points were then used to construct channel gradient curves for the Astoria, Eel, Bear Valley, and Mendocino channel pathways. These gradients are plotted on sheet 6 of this report and illustrate the similarities and differences between each of the pathways. Sheet 7 shows various views of the Mendocino/Mattole Canyon heads as an example of useful derivative information of the Seabeam bathymetric data. These views illustrate that the Mendocino pathway probably was directed from it's canyon mouth, to the northwest at an earlier time, but was diverted to the west along the base of the Mendocino Ridge by a major fault event in the recent past. Offset of the southwest channel wall is readily evident in views B and D. This apparent disruption complicates the turbidite history of the Mendocino pathway.

California;Oregon↗
USGS1999

Reconnaissance of chemical and physical characteristics of selected bottom sediments of the Caloosahatchee River and estuary, tributaries, and contiguous bays, Lee County, Florida, July 20-30, 1998

This report summarizes a reconnaissance study, conducted July 20-30, 1998, of chemical and physical characteristics of recently deposited bottom sediments in the Caloosahatchee River and Estuary. Recently deposited sediments were identified using an isotopic chronometer, Beryllium-7 (7Be), a short-lived radioisotope. Fifty-nine sites were sampled in an area that encompasses the Caloosahatchee River (River) about three miles upstream from the Franklin Lock (S-79), the entire tidally affected length of the river (estuary), and the contiguous water bodies of Matlacha Pass, San Carlos Bay, Estero Bay, Tarpon Bay, and Pine Island Sound in Lee County, Florida. Bottom sediments were sampled for 7Be at 59 sites. From the results of the 7Be analysis, 30 sites were selected for physical and chemical analysis. Sediments were analyzed for particle size, total organic carbon (TOC), trace elements, and toxic organic compounds, using semiquantitative methods for trace elements and organic compounds. The semiquantitative scans of trace elements indicated that cadmium, copper, lead, and zinc concentrations, when normalized to aluminum, were above the natural background range at 24 of 30 sites. Particle size and TOC were used to characterize sediment deposition patterns and organic content. Pesticides, polychlorinated biphenyls (PCBs), and carcinogenic polycyclic aromatic hydrocarbons (CaPAHs) were determined at 30 sites using immunoassay analysis. The semiquantitative immunoassay analyses of toxic organic compounds indicated that all of the samples contained DDT, cyclodienes as chlordane (pesticides), and CaPAHs. PCBs were not detected. Based on analyses of the 30 sites, sediments at 10 of these sites were analyzed for selected trace elements and toxic organic compounds, including pesticides, PCBs, and PAHs, using quantitative laboratory procedures. No arsenic or cadmium was detected. Zinc was detected at two sites with concentrations greater than the lower limit of the range of sediment contaminant concentrations that are usually or always associated with adverse effects (Florida Department of Environmental Protection's Sediment Quality Assessment Guidelines). Organochlorine pesticides were detected at four sites at concentrations below the reporting limits; there were no organophosphorus pesticides or PCBs detected. PAHs were detected at eight sites; however, only four sites had concentrations above the reporting limit.

Florida↗
USGS1999

Characteristics of the Alaskan 1-Km Advanced Very High Resolution Radiometer data sets used for analysis of vegetation biophysical properties

In this study, data characteristics for composited, multitemporal Advanced Very High Resolution Radiometer data sets for Alaska were assessed for a 7- year period from 1991 to 1997. This involved consideration of the satellite sensors used, data processing performed, and data set compilation, along with an analysis of acquisition date, solar zenith angle, satellite viewing angle, presence of clouds, and registration accuracy for each year. Each year?s worth of data are available on CD-ROM in byte format. All data sets have an initial start date of April 1, but had varying ending dates (mid-September to late October) because of satellite sensor malfunction or the presence of clouds or snow; no data set extended beyond October 31. Satellite scan angles were summarized in seven categories: data obtained at nadir, data within 30, 40, and 55 degrees of nadir, data greater than 55 degrees off nadir, and proportions of the data representing east or west look angles. Minimum, maximum, and average solar zenith angles were provided for each period. Estimates of cloud cover for each period were based on three tests: reflectance gross cloud test, channel 3 minus channel 4, and channel 4 minus channel 5. Registration accuracy was estimated using a gray-level autocorrelation technique. Results of this investigation indicate that the composited data available on CD-ROM should be useful for a number of different regional assessments of Earth cover properties. However, caution is advised when using these data because (1) loss in precision from the conversion to a byte format, (2) low sun angles and high viewing angles in the September and October data, and (3) registration inaccuracies of 2 to 8 pixels.

Alaska↗
USGS1999

Organic compounds and trace elements in the Pocomoke River and tributaries, Maryland

In response to concern about recent blooms of the dinoflagellate, Pfiesteria piscicida, samples of sediment and water were collected from the lower Pocomoke River Basin and were screened for trace elements, pesticides, and other organic compounds. A large group of steroid and fatty acid methyl-ester compounds was detected in streamwater using gas chromatography/mass spectroscopy in scan mode. Some of these steroid compounds have been identified and further quantified in bed-sediment extracts. Spatial patterns of the concentrations of cholesterol suggest that these compounds are linked to the runoff of animal wastes into the river. Many of the organic compounds found in the Pocomoke River sediments have not yet been identified, but at least several are in the class of hormone compounds related to estradiols and have the potential to promote endocrine-disrupting effects in aquatic life. Particulate forms of arsenic and zinc are slightly elevated above normal levels for streams, but the sources for these elements are still undetermined. Several pesticides were found in low, parts-per-trillion concentrations, but were within the ranges commonly found in streams of this region.

Maryland↗
USGS1982

Palaeocopid and podocopid Ostracoda from the Lexington Limestone and Clays Ferry Formation (Middle and Upper Ordovician) of central Kentucky

The Middle through lower Upper Ordovician Lexington Limestone and lower part of the Clays Ferry Formation contain an abundant and diversified ostracode fauna. More than 10,000 specimens belonging to 39 genera and 53 species have been found in 73 collections made by members of the U.S. Geological Survey in cooperation with the Kentucky Geological Survey between 1961 and 1970. Five of the genera and 17 of the species are new. New taxa include the genera Gephyropsis, Ningulella, Phelobythocypris, Quasibollia, and Uninodobolba and the following species: Americoncha dubia, Ballardina millersburgia, Brevidorsa strodescreekensis, Ceratopsis asymme , trica C. fimbriata, Ctenobolbina ventrispinifera, Cystomatochilina reticulotiara, Easchmidtella sinuidorsata, Gephyropsis trachyreticulata, Jonesella gonyloba, Laccoprimitia claysferryensis, L. cryptomorphologica, Leperditella? perplexa, Ningulella paupera, Parenthatia sadievillensis, Silenis kentuckyensis, and Uninodobolba franklinensis. In addition, a new species, Quasibollia copelandi, is described from the Middle Ordovician of Ontario. The type specimens of ostracodes previously described from these formations but not represented in the recent collections are redescribed and refigured. The genus Warthinia Spivey, 1939, is reinstated for Ordovician bolliids with two to four nodes, and the genus Ceratopsis Ulrich, 1894, is reviewed with new figures of all known North American species of the genus. Forty-four collections included enough specimens to warrant quantitative analysis. The temporal and spatial distribution of the genera were defined by using Q-mode cluster analysis based on Sorensen's quantified coefficient of association. The resulting phenogram indicated the existence of eight clusters; these clusters were characterized by calculation of constancy and fidelity measures for each of the variables. Generic diversity, compound generic diversity, and lithologic associations were scanned in an attempt to delineate the paleoecologic regime of each cluster. In general, a trend can be seen in which the higher diversity Phelobythocypris-dominated clusters are found in the muddier rocks and less diverse, highly Ceratopsisdominated clusters in the predominantly carbonate members. An exception to this generalization is found in the limestones of the Strodes Creek Member of the Lexington Limestone which has the highest ostracode diversity. However, the Strodes Creek is found entirely within the confines of the muddy Millersburg Member of the Lexington and is believed to represent a similar environment. Diversity differences in these ostracode associations are thought to be controlled mainly by substrate and kinetic energy level. We suggest that the associations may represent ecologically controlled ostracode assemblages.

Professional Paper↗
USGS1980

Crystals of coexisting alunite and jarosite, Goldfield, Nevada

Alunite (KAl 3 (SO 4 ) 2 (OH) 6 ) and jarosite (KFe 3 (SO 4 ) 2 (OH) 6 ) coexist in optically continuous crystals in a sample from the Goldfield mining district, Esmeralda County, Nev. Beam scans with an electron microprobe indicate that no intermediate minerals of the solid-solution series alunite-jarosite occur in these crystals. An Eh-pH diagram demonstrating the equilibrium relations between alunite, jarosite, and geothite suggests the crystals most likely developed by a rise in Eh, which oxidized ferrous to ferric iron, thus allowing jarosite to precipitate.

Nevada↗