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At least 595 records · Page 33Linked to original sources
USGS2005

Bogue Phalia watershed in Mississippi selected for a national water-quality study

The U.S. Geological Survey (USGS) is studying seven watersheds across the Nation to better understand how natural factors and agricultural management practices (AMPs) affect the transport of water and chemicals. Natural factors include climate and landscape (soil type, topography, geology), and AMPs include practices related to tillage, irrigation, and chemical application. The study approach is similar in each watershed so that we can compare and contrast the results and more accurately predict conditions in other agricultural settings.

Mississippi↗
USGS1980

The distribution and mobility of uranium in glassy and zeolitized tuff, Keg Mountain area, Utah, U.S.A.

The distribution and mobility of uranium in a diagenetically altered, 8 Ma old tuff in the Keg Mountain area, Utah, are modelled in this study. The modelling represents an improvement over similar earlier studies in that it: (1) considers a large number of samples (76) collected with good geologic control and exhibiting a wide range of alteration; (2) includes radiometric data for Th, K and RaeU (radium equivalent uranium) as well as U; (3) considers mineralogic and trace-element data for the same samples; and (4) analyzes the mineral and chemical covariation by multivariate statistical methods. The variation of U in the tuff is controlled mainly by its primary abundance in glass and by the relative abundance of non-uraniferous detritus and uraniferous accessory minerals. Alteration of glass to zeolite, even though extensive, caused no large or systematic change in the bulk concentration of U in the tuff. Some redistribution of U during diagenesis is indicated by association of U with minor alteration products such as opal and hydrous Fe-Mn oxide minerals. Isotopic studies indicate that the zeolitized tuff has been open to migration of U decay products during the last 0.8 Ma. The tuff of Keg Mountain has not lost a statistically detectable fraction of its original U, even though it has a high (??? 9 ppm) trace U content and has been extensively altered to zeolite. Similar studies in a variety of geological environments are required in order to identify the particular combination of conditions most favorable for liberation and migration of U from tuffs. ?? 1980.

Chemical Geology↗
USGS2016

Chemical abrasion-SIMS (CA-SIMS) U-Pb dating of zircon from the late Eocene Caetano caldera, Nevada

Zircon geochronology is a critical tool for establishing geologic ages and time scales of processes in the Earth's crust. However, for zircons compromised by open system behavior, achieving robust dates can be difficult. Chemical abrasion (CA) is a routine step prior to thermal ionization mass spectrometry (TIMS) dating of zircon to remove radiation-damaged parts of grains that may have experienced open system behavior and loss of radiogenic Pb. While this technique has been shown to improve the accuracy and precision of TIMS dating, its application to high-spatial resolution dating methods, such as secondary ion mass spectrometry (SIMS), is relatively uncommon. In our efforts to U-Pb date zircons from the late Eocene Caetano caldera by SIMS (SHRIMP-RG: sensitive high resolution ion microprobe, reverse geometry), some grains yielded anomalously young U-Pb ages that implicated Pb-loss and motivated us to investigate with a comparative CA and non-CA dating study. We present CA and non-CA 206 Pb/ 238 U ages and trace elements determined by SHRIMP-RG for zircons from three Caetano samples (Caetano Tuff, Redrock Canyon porphyry, and a silicic ring-fracture intrusion) and for R33 and TEMORA-2 reference zircons. We find that non-CA Caetano zircons have weighted mean or bimodal U-Pb ages that are 2–4% younger than CA zircons for the same samples. CA Caetano zircons have mean U-Pb ages that are 0.4–0.6 Myr older than the 40 Ar/ 39 Ar sanidine eruption age (34.00 ± 0.03 Ma; error-weighted mean, 2σ), whereas non-CA zircons have ages that are 0.7–1.3 Myr younger. U-Pb ages do not correlate with U (~ 100–800 ppm), Th (~ 50–300 ppm) or any other measured zircon trace elements (Y, Hf, REE), and CA and non-CA Caetano zircons define identical trace element ranges. No statistically significant difference in U-Pb age is observed for CA versus non-CA R33 or TEMORA-2 zircons. Optical profiler measurements of ion microprobe pits demonstrate consistent depths of ~ 1.6 μm for CA and non-CA Caetano, R33 and TEMORA-2 zircons, and do not indicate variations in secondary ion sputtering rates due to chemical or structural changes from the CA treatment. Our new data underscore the potential for cryptic Pb-loss to go unrecognized in other geologically young magmatic centers that do not have zircons with high U, statistically discordant isotope ratios, high common Pb, or metamict textures.

Nevada↗
USGS2014

Mercury speciation in the Mt. Amiata mining district (Italy): interplay between urban activities and mercury contamination

A fundamental step to evaluate the biogeochemical and eco-toxicological significance of Hg dispersion in the environment is to determine speciation of Hg in solid matrices. In this study, several analytical techniques such as scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), sequential chemical extractions (SCEs), and X-ray absorption spectroscopy (XANES) were used to identify Hg compounds and Hg speciation in samples collected from the Mt. Amiata Hg mining district, southern Tuscany, Italy. Different geological materials, such as mine waste calcine (retorted ore), soil, stream sediment, and stream water suspended particulate matter were analyzed. Results show that the samples were generally composed of highly insoluble Hg compounds such as sulphides (HgS, cinnabar and metacinnabar), and more soluble Hg halides such as those associated with the mosesite group. Other moderately soluble Hg compounds, HgCl 2 , HgO and Hg 0 , were also identified in stream sediments draining the mining area. The presence of these minerals suggests active and continuous runoff of soluble Hg compounds from calcines, where such Hg compounds form during retorting, or later in secondary processes. Specifically, we suggest that, due to the proximity of Hg mines to the urban center of Abbadia San Salvatore, the influence of other anthropogenic activities was a key factor for Hg speciation, resulting in the formation of unusual Hg-minerals such as mosesite.

Tuscany↗
USGS1955

Reconnaissance of geology and ground water in the lower Grand River valley, South Dakota, with a section on Chemical quality of the ground water

The area described in this report is the flood plain of the Grand River and the bordering benchlands in Perkins and Corson Counties, S. Dak., from a point about 6 miles west of the town of Shadehill to the confluence of the Grand and Missouri Rivers near Mobridge. The exposed bedrock formations include the Pierre shale, the Fox Hills sandstone, and the Hell Creek formation of Late Cretaceous age, and-the Ludlow member of the Fort Union formation of Tertiary (Paleocene) age. Some stringers of the Cannonball formation probably interfinger with beds of the Ludlow member but none of the former was identified during the field investigations. The Pierre shale is exposed from the mouth of the Grand River to approximately the center of the area. Although a few wells in the area obtain water from this formation, it is not generally considered to be a source of supply. The Fox Hills sandstone, the Hell Creek formation, and the Ludlow member of the Fort Union formation are exposed successively upstream and, where saturated, yield small to moderate quantities of water to wells. Unconsolidated deposits of silt, sand, and gravel occur in several physiographic positions; they underlie the high benchland on both sides of the river, the poorly defined terraces along the river, and the flood plain throughout its entire length. Possibly all these unconsolidated deposits are water bearing; however, where the deposits on the benchland and in the terraces are dissected by streams, they probably contain little or no water. The average depth to ground water along the lower Grand River valley is about 17 feet. Probably, the flow of ground water in the bottom lands is nearly parallel to and slightly toward the surface stream. The measurements of the water level in observation wells for the period 1946-48 indicate that the fluctuations of the water table are small. The results of analyses of 13 samples of ground water from the alluvium and the Hell Creek formation show that the suitability of the ground water for use varies because of the considerable range in mineralization and composition. Dissolved solids ranged from 343 to 4,250 parts per million (ppm), hardness from 11 to 1,130 ppm, and percentage of sodium from 25 to 98. Concentrations of some of the individual constituents exceed standards of the United States Public Health Service. The water is moderately hard and contains undesirable amounts of iron and moderate to large amounts of dissolved solids. In general, the water quality ranges from excellent to unsuitable for irrigation use. The result of the mixing of the ground water with recharge water from Shadehill Reservoir cannot be predicted on the basis of available data. The geologic and hydrologic data in this report were obtained from earlier reports and from field observations during the period 1946-48. The report includes a geologic map and tabulated well records.

South Dakota↗
USGS2013

Relationships between the health of Alaska Native communities and our environment -- phase 1, exploring and communicating

Alaska Natives depend on local natural resources for nutritional and, for many, spiritual health. As a result, public health in Alaska is strongly influenced by the relationship between people and their surrounding physical, chemical, and biological environments. Alaska is vast with diverse wildlife and plant communities that are valued as subsistence foods (fig. 1). These resources are supported by equally diverse ecosystems and their underpinning landforms and geologies. The U.S. Geological Survey (USGS) is attempting to integrate physical, chemical, and biological information to better describe current (2013) environments and project scenarios for the future. Integrating ecological data into the public health dialogue is challenging for the more than 280 rural communities of Alaska. This fact sheet reviews a recent USGS effort, the Geographic Information System (GIS) Native Health Project, to better incorporate scientific information into such dialogue.

Alaska↗
USGS2016

Effect of wastewater treatment facility closure on endocrine disrupting chemicals in a Coastal Plain stream

Wastewater treatment facility (WWTF) closures are rare environmental remediation events; offering unique insight into contaminant persistence, long-term wastewater impacts, and ecosystem recovery processes. The U.S. Geological Survey assessed the fate of select endocrine disrupting chemicals (EDC) in surface water and streambed sediment one year before and one year after closure of a long-term WWTF located within the Spirit Creek watershed at Fort Gordon, Georgia. Sample sites included a WWTF-effluent control located upstream from the outfall, three downstream effluent-impacted sites located between the outfall and Spirit Lake, and one downstream from the lake's outfall. Prior to closure, the 2.2-km stream segment downstream from the WWTF outfall was characterized by EDC concentrations significantly higher ( α = 0.05) than at the control site; indicating substantial downstream transport and limited in-stream attenuation of EDC, including pharmaceuticals, estrogens, alkylphenol ethoxylate (APE) metabolites, and organophosphate flame retardants (OPFR). Wastewater-derived pharmaceutical, APE metabolites, and OPFR compounds were also detected in the outflow of Spirit Lake, indicating the potential for EDC transport to aquatic ecosystems downstream of Fort Gordon under effluent discharge conditions. After the WWTF closure, no significant differences in concentrations or numbers of detected EDC compounds were observed between control and downstream locations. The results indicated EDC pseudo-persistence under preclosure, continuous supply conditions, with rapid attenuation following WWTF closure. Low concentrations of EDC at the control site throughout the study and comparable concentrations in downstream locations after WWTF closure indicated additional, continuing, upstream contaminant sources within the Spirit Creek watershed. 

Georgia↗
USGS1906

Report on the operations of the coal-testing plant of the United States Geological Survey at the Louisiana Purchase Exposition, Saint Louis, Missouri, 1904: Part I.--Field work, classification of coals, chemical work

The authority for conducting at the Louisiana Purchase Exposition an investigation of the coals and lignites of the United States is contained in the act of Congress providing for the urgent deficiencies in the appropriations for the fiscal year 1905, and approved February 18, 1904, as follows: For analyzing and testing. at the Louisiana Purchase Exposition the coals and lignites of the United States, in order to determine their fuel values mid the most economical method for their utilization for different purposes, under the supervision of the Director of the United States Geological Survey, thirty thousand dollars, to be available until expended: Provided, That all testing machinery and all coals and lignites to be tested shall be contributed without charge to the Government. In the general deficiency bill approved April 27, 1904, an additional appropriation of $30,000 was provided, making the total sum appropriated for this work $60,000. For carrying out the provisions of these acts the Director of the Geological Survey appointed a committee, consisting of Edward W. Parker, Joseph A. Holmes, and Marius R. Campbell, to direct the construction and operation of the plant. It will be observed that under the law authorizing this work all of the testing machinery and all of the coals to be tested had to be furnished to the Government free of charge. Under these conditions it was not possible to equip an ideal testing plant, and the assembling and construction of such equipment as conld be obtained under these provisions entailed some annoying delays in the completion of the plant. In addition to this, the delivery of a considerable quantity of operating and conveying apparatus purchased from the Link Belt Machinery Company, of Chicago, was delayed by a strike in the works of that company. As a result of these combined influences the plant was not put in operation until the 1st of September. Notwithstanding these delays, the committee feels that through the hearty and patriotic cooperation of a large number of manufacturers of apparatus and machinery it was able to collect and install, within a notably short time, a testing plant that was well suited for such pioneer work.

Missouri↗
USGS1995

Detailed lithologic log of the Dow Chemical #1 B.L. Garrigan Drill Hole, Mississippi County, Arkansas

The geology and tectonic setting of the New Madrid region in southeastern Missouri has received considerable attention because of the area's high seismic activity. The largest recorded earthquakes in this area occurred in the winter of 1811-1812. These earthquakes has estimated magnitudes as large as 8.0 on the Richter scale (Johnsonton and Kanter, 1990) and affected an area of about 1 million square miles (Fuller, 1912). Today, an area of continuously high seismic activity defines the New Madrid seismic zone, which extends from northeastern Arkansas into southeastern Missouri and northwestern Tennessee. Seismicity is locally concentrated along two subsurface archers--the Blytheville and Pascola (Hildenbrand and others, 1977; Crone and others, 1985; Hildenbrand, 1985; McKeown, 1988). The Padcola arch is not pertinent to this study and, therefore will not be discusses further. The Blytheville arch is located in and is subparallel to the axis of the northeast-southwest-trending Reelfoot structural basin, which formed during early Paleozoic rifting (Ervin and McGinnis, 1975; fig. 1). The Reelfoot basin is filled with Cambrian and Ordovician sedimentary rocks (Grohskopf, 1955; Howe, 1984; Houseknevht, 1989; Collins and others, 1992) that are uncomfortably overlain by Cretacaous and Tertiary sedimentary rocks and underlain by crystalline rocks of the eastern granite-rhyolite province (see Bickford and others, 1986). The presence of some Late Proterozoic sedimentary rocks in the Reelfoot basin currently cannot be ruled out. The Dow Chemical #1 B.L. Garrigan drill hole (hereafter, Garrigan) penetrated Paleozoic rocks on the Blytheville arch. The Garrigan is locted in the Reelfoot basin in the NW1/4, NW1/4 sec. 28, T. 15 N., R. 10 E., Mississippi County, Arkansas (fig. 1) and was completed to a total depth of 12,038 ft from a ground elevation of 239 ft on April 11, 1982 (Swolfs, 1991). The Garrigan is the only reported drill hole that penetrates the subsurface Blytheville arch and is an important source of core from the Reelfoot basin (Collins and others, 1992). Therefore, this drill hole is important for understanding structure and Paleozoic stratigraphy in a basin where stratigraphic and structural data are sparse. Rocks in the Garrigan were originally logged and described by J.R. Howe (personal communication to D.S. Collins, 1990) and published as a composite stratigraphic section along with the rock description for the Dow Chemical #1 Wilson drill hole (Howe, 1984). F.A. McKeown later relogged the rocks in the Garrigan and presented a generalized log in McKeown and others (1990). Swolfs (1991) presented another version of the Garrigan drill-hole geologic section (fig. 2). Aided by new biostratigraphic information, Taylor and others (1991) corrected major errors in the characterization and correlation of rocks in the Garrigan (fig. 2). Collins (1991) described the insoluble residues from the cuttings of the Garrigan, but could not correlate them with the insoluble resides from rocks of the carbonate platform west of the basin. However Taylor and others (1991), Collins and others (1992), and Collins and Bohm (1993) did correlate fossils from the Garrigan to other drill holes in the Reelfoot basin and adjacent areas. Using these correlated data, Collins and Bohm (1993) provided information on the structural relief across a part of the Reelfoot basin. Collins and others (1992) also interpreted the depositional setting for the Paleozoic rocks of the Garrigan. This report presents a detailed lithologic log of the Paleozoic rocks penetrated by the Garrigan that differs from the lithologic logs of previous workers (Howe, 1984; McKeown and others, 1990; see also Dart, 1992, p. 18-19). The lithologic descriptions of the Garrigan are derived from observations of well cuttings and core. Cored intervals used were 11,426-11,402 ft, 10,229-10,200 ft, and 8,002-7,979 ft. These intervals were the only intervals cored during the Garrigan drill project. Detailed analyses of the core will be described in a subsequent report.

Arkansas↗
USGS1960

Origin and chemical composition of evaporite deposits

A comparative study of marine evaporite deposits forming at the present time along the pacific coast of central Mexico and evaporite formations of Permian age in West Texas Basin was made in order to determine if the modern sediments provide a basis for understanding environmental conditions that existed during deposition of the older deposits. The field work was supplemented by investigations of artificial evaporite minerals precipitated in the laboratory and by study of the chemical composition of halite rock of different geologic ages. The environment of deposition of contemporaneous marine salt deposits in Mexico is acidic, is strongly reducing a few centimeters below the surface, and teems with microscopic life. Deposition of salt, unlike that of many other sediments, is not wholly a constructional phenomenon. Permanent deposits result only if a favorable balance exists between deposition in the dry season and dissolution in the wet season. Evaporite formations chosen for special study in the West Texas Basin are, in ascending order, the Castile, Salado, and Rustler formations, which have a combined thickness of 1200 meters. The Castile formation is largely composed of gypsum rock, the Salado, halite rock, and the Rustler, quartz and carbonate sandstone. The lower part of the Castile formation is bituminous and contains limestone laminae. The Castile and Rustler formations thicken to the south at the expense of salt of the intervening Salado formation. The clastic rocks of the Rustler formation are interpreted as the deposits of a series of barrier islands north of which halite rock of the Salado was deposited. The salt is believed to have formed in shallow water of uniform density that was mixed by the wind. Where water depth exceeded the depth of the wind mixing, density stratification developed, and gypsum was deposited. Dense water of high salinity below the density discontinuity was overlain by less dense, more normally saline water which was derived from the sea to the south. Mixing of the two water layers at their interface diluted the lower layer so as to prevent halite formation, but at the same time the depressed solubility of calcium sulfate in the mixture at the interface caused precipitation of gypsum. The upper water layer is believed to have supported a flourishing microscopic biota whose remains descended into semisterile brine below where reducing conditions prevailed. This environment generated the bituminous gypsum rock. At times, microcrystalline calcium carbonate of probable biochemical origin formed in the upper layer and settled below to form limestone laminae such as those of the lower part of the Castile formation. Chemical analyses of Permian and present-day salt were compared with analyses of marine salt as old as Cambrian age to determine if evaporite deposits can contribute information on the geologic history of sea water. The results contain uncertainties that cannot be fully resolved, but they suggest that the ratio between ions in sea water has been approximately constant since Precambrian time. In addition, the abrupt initial appearance of rock salt deposits in Cambrian time suggests that the Precambrian ocean may have been rather dilute, but this apparent relationship also could have been caused by other factors.

Open-File Report↗
USGS1969

The relationship of the rare-earth composition of minerals to geological environment

It has been known for a long time that the composition of the lanthanides in minerals is controlled to a large degree by crystallo-chemical factors, but is also greatly influenced by changes in geological environment. In general, igneous rocks rich in silica are favourable for the concentration of the heavy lanthanides and yttrium; those low in silica and high in carbonate are favourable for the concentration of the light lanthanides. These generalizations are illustrated by summaries of the available data on monazite, sphene, and apatite from different geological environments. Apatite of marine sedimentary origin (a large potential source of rare earths) shows marked depletion of cerium, as has been noted previously for sea water.

Geochimica et Cosmochimica Acta↗
USGS1992

Mount St. Helens a decade after the 1980 eruptions: magmatic models, chemical cycles, and a revised hazards assessment

Available geophysical and geologic data provide a simplified model of the current magmatic plumbing system of Mount St. Helens (MSH). This model and new geochemical data are the basis for the revised hazards assessment presented here. The assessment is weighted by the style of eruptions and the chemistry of magmas erupted during the past 500 years, the interval for which the most detailed stratigraphic and geochemical data are available. This interval includes the Kalama (A. D. 1480-1770s?), Goat Rocks (A.D. 1800-1857), and current eruptive periods. In each of these periods, silica content decreased, then increased. The Kalama is a large amplitude chemical cycle (SiO2: 57%-67%), produced by mixing of arc dacite, which is depleted in high field-strength and incompatible elements, with enriched (OIB-like) basalt. The Goat Rocks and current cycles are of small amplitude (SiO2: 61%-64% and 62%-65%) and are related to the fluid dynamics of magma withdrawal from a zoned reservoir. The cyclic behavior is used to forecast future activity. The 1980-1986 chemical cycle, and consequently the current eruptive period, appears to be virtually complete. This inference is supported by the progressively decreasing volumes and volatile contents of magma erupted since 1980, both changes that suggest a decreasing potential for a major explosive eruption in the near future. However, recent changes in seismicity and a series of small gas-release explosions (beginning in late 1989 and accompanied by eruption of a minor fraction of relatively low-silica tephra on 6 January and 5 November 1990) suggest that the current eruptive period may continue to produce small explosions and that a small amount of magma may still be present within the conduit. The gas-release explosions occur without warning and pose a continuing hazard, especially in the crater area. An eruption as large or larger than that of 18 May 1980 (???0.5 km3 dense-rock equivalent) probably will occur only if magma rises from an inferred deep (???7 km), relative large (5-7 km3) reservoir. A conservative approach to hazard assessment is to assume that this deep magma is rich in volatiles and capable of erupting explosively to produce voluminous fall deposits and pyroclastic flows. Warning of such an eruption is expectable, however, because magma ascent would probably be accompanied by shallow seismicity that could be detected by the existing seismic-monitoring system. A future large-volume eruption (???0.1 km3) is virtually certain; the eruptive history of the past 500 years indicates the probability of a large explosive eruption is at least 1% annually. Intervals between large eruptions at Mount St. Helens have varied widely; consequently, we cannot confidently forecast whether the next large eruption will be years decades, or farther in the future. However, we can forecast the types of hazards, and the areas that will be most affected by future large-volume eruptions, as well as hazards associated with the approaching end of the current eruptive period. ?? 1992 Springer-Verlag.

Bulletin of Volcanology↗
USGS2022

Hyperspectral remote sensing of white mica: A review of imaging and point-based spectrometer studies for mineral resources, with spectrometer design considerations

Over the past ~30 years, hyperspectral remote sensing of chemical variations in white mica have proven to be useful for ore deposit studies in a range of deposit types. To better understand mineral deposits and to guide spectrometer design, this contribution reviews relevant papers from the fields of remote sensing, spectroscopy, and geology that have utilized spectral changes caused by chemical variation in white micas. This contribution reviews spectral studies conducted at the following types of mineral deposits: base metal sulfide, epithermal, porphyry, sedimentary rock hosted gold deposits, orogenic gold, iron oxide copper gold, and unconformity-related uranium. The structure, chemical composition, and spectral features of white micas, in this contribution defined as muscovite, paragonite, celadonite, phengite, illite, and sericite, are given. Reviewed laboratory spectral studies determined that shifts in the position of the white mica 2200 nm combination feature of 1 nm correspond to a change in Al oct content of approximately ±1.05%. Many of the reviewed spectral studies indicated that a shift in the position of the white mica 2200 nm combination feature of 1 nm was geologically significant. A sensitivity analysis of spectrometer characteristics; bandpass, sampling interval, and channel position, is conducted using spectra of 19 white micas with deep absorption features to determine minimum characteristics required to accurately measure a shift in the position of the white mica 2200 nm combination feature. It was determined that a sampling interval < 16.3 nm and bandpass <17.5 nm are needed to achieve a root mean square error (RMSE) of 2 nm, whereas a sampling interval < 8.8 nm and bandpass <9.8 nm are needed to achieve a RMSE of 1 nm. For comparison, commonly used imaging spectrometers HyMap, AVIRIS-Classic, SpecTIR®'s AisaFENIX 1K, and HySpex tm SWIR 384 have 2.1, 1.2, 0.96, and 0.95 nm RMSE in determining the position of the 2200 nm white mica combination feature, respectively. An additional sensitivity analysis is conducted to determine the effect of signal to noise ratio (SNR) on the RMSE of the position of the white mica 2200 nm combination feature, using spectra of 18 white micas with deep absorption features. For a spectrometer with sampling interval and bandpass of 1 nm, we estimate that RMSEs of 1 and 1.5 nm are achievable with spectra having a minimum SNR of approximately 246 and 64, respectively. For a spectrometer with sampling interval and bandpass of 5 nm, we estimate that RMSEs of 1 and 1.5 nm are attainable with spectra having a minimum SNR of approximately 431 and 84, respectively. When using a spectrometer with a sampling interval 8.8 nm and a bandpass of 9.8 nm, a RMSE of 1 is only achievable with convolved, noiseless reference spectra. For the 8.8_9.8 nm spectrometer, spectra with SNR of 250 and 100 result in RMSE of 1.1 and 1.3, respectively. Therefore, fine spectral resolution characteristics achieve RMSEs better than 1 nm for high SNR spectra while spectrometers with coarse spectral resolution have larger RMSE, perform well with noisy data, and are useful for white mica studies if RMSE of 1.1 to 1.5 nm is acceptable.

Remote Sensing of Environment↗
USGS1996

Selected hydrologic data for the Beaver Dam Wash area, Washington County, Utah, Lincoln County, Nevada, and Mohave County, Arizona, 1991-95

The hydrologic data in this report were collected in Beaver Dam Wash and adjacent areas of Washington County, Utah, Lincoln County, Nevada, andMohave County, Arizona, from 1991 to 1995; some historical data from as far back as 1932 are included for comparative purposes. The data include records of about 100 wells, drillers' and geologic logs of selected wells, and results of chemical analyses of water from wells, springs, and surface-water sites. Discharge, water temperature, and specific-conductance measurements are reported for 33 surface-water and spring sites. Daily mean discharge data are reported for two U.S. Geological Survey streamflow-gaging stations on Beaver Dam Wash (1992-95). The data were collected as part of a study done by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Resources; the Nevada Department of Conservation and Natural Resources; and the Arizona Department of Water Resources.

Arizona, Nevada, Utah↗
USGS1985

Total chemical management in photographic processing

The mission of the U. S. Geological Survey's Earth Resources Observation Systems (EROS) Data Center is to produce high-quality photographs of the earth taken from aircraft and Landsat satellite. In order to meet the criteria of producing research-quality photographs, while at the same time meeting strict environmental restrictions, a total photographic chemical management system was installed. This involved a three-part operation consisting of the design of a modern chemical analysis laboratory, the implementation of a chemical regeneration system, and the installation of a waste treatment system, including in-plant pretreatment and outside secondary waste treatment. Over the last ten years the result of this program has yielded high-quality photographs while saving approximately 30,000 per year and meeting all Environmental Protection Agency (EPA) restrictions.

Journal of Imaging Technology↗