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At least 1,117 records · Page 62Linked to original sources
USGS2012

Physical setting and natural sources of exposure to carcinogenic trace elements and radionuclides in Lahontan Valley, Nevada

In Lahontan Valley, Nevada, arsenic, cobalt, tungsten, uranium, radon, and polonium-210 are carcinogens that occur naturally in sediments and groundwater. Arsenic and cobalt are principally derived from erosion of volcanic rocks in the local mountains and tungsten and uranium are derived from erosion of granitic rocks in headwater reaches of the Carson River. Radon and 210Po originate from radioactive decay of uranium in the sediments. Arsenic, aluminum, cobalt, iron, and manganese concentrations in household dust suggest it is derived from the local soils. Excess zinc and chromium in the dust are probably derived from the vacuum cleaner used to collect the dust, or household sources such as the furnace. Some samples have more than 5 times more cobalt in the dust than in the local soil, but whether the source of the excess cobalt is anthropogenic or natural cannot be determined with the available data. Cobalt concentrations are low in groundwater, but arsenic, uranium, radon, and 210 Po concentrations often exceed human-health standards, and sometime greatly exceed them. Exposure to radon and its decay products in drinking water can vary significantly depending on when during the day that the water is consumed. Although the data suggests there have been no long term changes in groundwater chemistry that corresponds to the Lahontan Valley leukemia cluster, the occurrence of the very unusual leukemia cluster in an area with numerous 210 Po and arsenic contaminated wells is striking, particularly in conjunction with the exceptionally high levels of urinary tungsten in Lahontan Valley residents. Additional research is needed on potential exposure pathways involving food or inhalation, and on synergistic effects of mixtures of these natural contaminants on susceptibility to development of leukemia.

Nevada↗
USGS1998

Radionuclides in fly ash and bottom ash: Improved characterization based on radiography and low energy gamma-ray spectrometry

Two radiation-based techniques for determining the distribution and relative abundance of radionuclides are described, and applied to a suite of fly ash and bottom ash samples from a Kentucky power plant. The technique of fission-track radiography provides new observations of the variety of uranium hosts and of uranium distribution in individual particles of fly ash, and thus aids prediction of the leachability of uranium during long-term disposal or utilization of fly ash. Uranium is largely dispersed within glassy components of fly ash particles and shows little evidence for obvious surface enrichment that could be attributed to secondary adsorption. The technique of low energy gamma-ray spectrometry provides simultaneous, non-destructive determination of the relative abundance of 238 U, 226 Ra, 228 Ra and 210 Pb in representative 150–250 g samples. The measurements provide a means for screening samples to determine if the combustion process causes significant preferential redistribution of radionuclides that could affect their subsequent mobility. Results indicate that radium isotopes are not significantly (within 10–15%) fractionated from parent 238 U and 232 Th during coal combustion. In contrast, 210 Pb appears to be preferentially enriched in some samples of fly ash, and depleted in bottom ash relative to 238 U and 226 Ra. In this application 210 Pb acts as a tracer for elemental lead, and confirms the expected greater volatility of Pb compared to more refractory elements during coal combustion.

Fuel↗
USGS1985

Isotopic studies of the late Archean plutonic rocks of the Wind River Range, Wyoming

Isotopic studies of the Rb-Sr and U-Th-Pb systems in whole-rock samples and the U-Pb systematics for zircons document the existence of two late Arehean intrusive events in the Wind River Range. All of the systems examined indicate an age of ∼2,630 ± 20 m.y. for the Louis Lake batholith. Apparent ages for the Bears Ears pluton range from 2,504 ± 40 m.y. to 2,575 ± 50 m.y. The scatter in apparent ages for the Bears Ears pluton does not appear to be primarily the result of disturbance by postintrusive events, but it may be explained by an isotopically inhomogenous magma at the time of intrusion. Data for a few samples indicate that the Wind River Range was affected locally by a postmagmatic hydrothermal event that was approximately Tertiary in age. This event lowered δ 18 O values and disturbed parent-daughter relationships in most of the isotopic systems investigated, but it was recent enough that there is no demonstrable effect in the Pb-Pb system. The Bears Ears pluton has some chemical and petrologic features that are similar to those reported for the granites in the Granite Mountains to the east. These granites are spatially associated with low-temperature uranium deposits of Tertiary age and have been shown to have lost large amounts of uranium during the early to middle Tertiary. U-Pb systematics indicate, however, that the low to moderate uranium contents and highly variable Th/U values noted for the Bears Ears pluton are best interpreted as being primary features. If uranium was lost after magma generation, the loss most likely occurred at the time of intrusion. Such a loss could account for uraniferous Precambrian pegmatites southwest of the main part of the Range. The two intrusive units apparently were derived from different protoliths that were formed during early to middle Archean. Initial isotopic ratios and petrochemistry for the Louis Lake batholith are consistent with an early Archean trondhjemitic to tonalitic source. The protolith for the Bears Ears pluton must have been more evolved and somewhat younger. Inconsistencies as to the degree of evolution of this protolith, as inferred from isotopic and trace-element data, suggest that the protolith may have been subjected to high-grade meta-morphism that caused loss of Rb and U prior to generation of the magma.

Wyoming↗
USGS1957

Effects of radon in drill holes on gamma-ray logs

Drill holes in uranium deposits in the Todilto limestone of Late Jurassic age near Grants, New Mexico, do not yield duplicate gamma-ray logs when probed at different times; some logs show equivalent uranium greatly in excess, in thickness and grade, of the chemical and laboratory radiometric analyses. Radon and its daughter products principally cause the discrepancies. Experimental work was undertaken by the writers to learn the relations of the radon to the uranium deposits and its behavior under different physical conditions. The work is based on the interpretation of about 600 gamma-ray logs, taken from 480 drill holes.Abnormally high amounts of radon, referred to here as contamination, ranged from barely detectable amounts to amounts that emitted as much radiation as ore-grade material. Most contaminated holes were in the higher-grade ore, and the contamination increased with elapsed time after drilling. Geologic conditions favorable for contamination by radon and its daughter products in drill holes are: proximity to uranium deposits and fractured or highly permeable rocks above the water table. Most drill holes can be decontaminated by blowing them out with compressed air or filling them with water. Water, however, tends to reduce the thickness-times-grade figures below the amounts determined in air.

New Mexico↗
USGS1965

Gamma-ray spectrometer studies of hydro-thermally altered rocks

The uranium, thorium, and potassium content of hydrothermally altered rocks in the vicinity of several copper and copper-lead-zinc deposits in Arizona was determined by chemical analysis. Potassium in the more intensely altered zones is about twice that in unaltered areas. There is no corresponding increase in thorium, so a higher potassium/thorium ratio also results from alteration; abnormally high uranium, locally in secular disequilibrium, was observed at the Bagdad porphyry copper deposit. A truck-mounted gammarray spectrometer was used to obtain a spectrum of gamma emission at each sample location. Equating the spectrometric with the chemical data gave standard errors of 0.6 percent potassium, 3 ppm thorium, and 10 ppm uranium for the outcrop analyses with the spectrometer . The amount of potassium introduced by hydrothermal alteration is thought sufficient in quantity to be detected by either surface or aerial spectrometry; spectrometric detection of anomalous uranium is probably marginal, owing to the disequilibrium. The potassium/thorium ratio may provide a means of distinguishing, in such surveys, between hydrothermally altered high-potassium zones and unaltered extrinsically high-potassium intrusives.

Economic Geology↗
USGS1954

Uranophane at Silver Cliff mine, Lusk, Wyoming

The uranium deposit at the Silver Cliff mine near Lusk, Wyo., consists primarily of uranophane which occurs as fracture fillings and small replacement pockets in faulted and fractured calcareous sandstone of Cambrian (?) age. The country rock in the vicinity of the mine is schist of pre-Cambrian age intruded by pegmatite dikes and is unconformably overlain by almost horizontal sandstone of Cambrian(?) age. The mine is on the southern end of the Lusk Dome, a local structure probably related to the Hartville uplift. In the immediate vicinity of the mine, the dome is cut by the Silver Cliff fault, a north-trending high-angle reverse fault about 1,200 feet in length with a stratigraphic throw of 70 feet. Uranophane, metatorbernite, pitchblende, calcite, native silver, native copper, chalcocite, azurite, malachite, chrysocolla, and cuprite have been deposited in fractured sandstone. The fault was probably mineralized throughout its length, but because of erosion, the mineralized zone is discontinuous. The principal ore body is about 800 feet long. The width and depth of the mineralized zone are not accurately known but are at least 20 feet and 60 feet respectively. The uranium content of material sampled in the mine ranges from 0.001 to 0.23 percent uranium, whereas dump samples range from 0.076 to 3.39 percent uranium.

Bulletin↗
USGS1959

Radioactive rare-earth deposit at Scrub Oaks mine, Morris County, New Jersey

A deposit of rare-earth minerals in the Scrub Oaks iron mine, Morris County, N. J., was mapped and sampled in 1955. The rare-earth minerals are mainly in coarse-grained magnetite ore and in pegmatite adjacent to it. Discrete bodies of rare-earth-bearing magnetite ore apparently follow the plunge of the main magnetite ore body at the north end of the mine. Radioactivity of the ore containing rare earths is about 0.2 to 0.6 mllliroentgens per hour. The principal minerals of the deposit are quartz, magnetite, hematite, albiteoligoclase, perthite and antiperthite. Xenotime and doverite aggregates and bastnaesite with intermixed leucoxene are the most abundant rare-earth minerals, and zircon, sphene, chevkinite, apatite, and monazite are of minor abundance in the ore. The rare-earth elements are partly differentiated into cerium-rich bastnaesite, chevkinite, and monazite, and yttrium-rich xenotime and doverite. Apatite, zircon, and sphene contain both cerium and yttrium group earths. Eleven samples of radioactive ore and rock average 0.009 percent uranium, 0.062 percent thorium, 1.51 percent combined rare-earth oxides including yttrium oxide and 24.8 percent iron. Scatter diagrams of sample data show a direct correlation between equivalent uranium, uranium, thorium, and combined rare^ earth oxides. Both cerium- and yttrium-group earths are abundant in the rare-earth minerals. Radioactive magnetite ore containing rare-earth minerals probably formed as a variant of the magnetite mineralization that produced the main iron ore of the Scrub Oaks deposit. The rare-earth minerals and the iron ore were deposited contemporaneously. Zircon crystals, probably deposited at the same time, have been determined by the Larsen method to be about 550 to 600 million years old (late Precambrian age). Uranium, thorium, and rare-earth elements are potential byproducts of iron in the coarse-grained magnetite ore.

New Jersey↗
USGS1953

Reconnaissance for radioactive deposits in the lower Yukon-Kuskokwim Highlands region, Alaska

Investigations in 1947 in the Lower Yukon-Kuskokwim region, Alaska found that previously reported radioactivity in the vicinity of Flat is due to uraniferous zircon, an accessory mineral in monzonite. The monzonite intrudes mafic igneous and Upper Cretaceous sedimentary rocks. The maximum equivalent-uranium content of the zircon is 0.14 percent, and the average content is probably near 0. 13 percent. Chemical analysis of one sample of the most radioactive zircon indicates approximately 0.12 percent uranium and 0.03 percent thoria. The radioactive elements apparently are most commonly associated with reddish-brown inclusions within the zircon crystals. Tests of sulfide-bearing veins, black shales, and other rock types in the area around Flat showed no significant amount of radioactive material. Although there is little likelihood of finding high-grade uranium deposits in the area covered by the 1947 investigation, the fact that the predominant radioactive element in the monzonite is uranium may indicate that other intrusives of the same age in the Lower Yukon-Kuskokwim region might also contain uraniferous material. Possibilities of concentrations in attendant contact-metamorphic or vein deposits are suggested by a previously reported occurrence of zeunerite in a copper lode in this same general belt of intrusives.

Circular↗
USGS2011

Groundwater quality of the Gulf Coast aquifer system, Houston, Texas, 2010

During March–December 2010, the U.S. Geological Survey, in cooperation with the city of Houston, collected source-water samples from 60 municipal supply wells in the Houston area. These data were collected as part of an ongoing study to determine concentrations, spatial extent, and associated geochemical conditions that might be conducive for mobility and transport of selected naturally occurring contaminants (selected trace elements and radionuclides) in the Gulf Coast aquifer system in the Houston area. In the summers of 2007 and 2008, a reconnaissance-level survey of these constituents in untreated water from 28 municipal supply wells was completed in the Houston area. Included in this report are the complete analytical results for 47 of the 60 samples collected in 2010—those results which were received from the laboratories and reviewed by the authors as of December 31, 2010. All of the wells sampled were screened in the Gulf Coast aquifer system; 22 were screened entirely in the Evangeline aquifer, and the remaining 25 wells contained screened intervals that intersected both Evangeline and Chicot aquifers. The data documented in this report were collected as part of an ongoing study to characterize source-water-quality conditions in untreated groundwater prior to drinking-water treatment. An evaluation of contaminant occurrence in source water provides background information regarding the presence of a contaminant in the environment. Because source-water samples were collected prior to any treatment or blending that potentially could alter contaminant concentrations, the water-quality results documented by this report represent the quality of the source water, not the quality of finished drinking water provided to the public. Samples were analyzed for major ions (calcium, magnesium, potassium, sodium, bromide, chloride, fluoride, silica, and sulfate), residue on evaporation (dissolved solids), trace elements (arsenic, barium, boron, chromium, iron, lithium, manganese, molybdenum, selenium, strontium, and vanadium), and selected radionuclides (gross alpha- and beta-particle activity [at 72 hours and 30 days], carbon-14, radium-226, radon-222, and uranium). Field measurements were made of selected physicochemical (relating to both physical and chemical) properties (oxidation-reduction potential, turbidity, dissolved-oxygen concentration, pH, specific conductance, water temperature, and alkalinity) and unfiltered sulfides. Similar to the results from the reconnaissance survey, physicochemical properties, major ions, and trace elements varied considerably. The ranges of selected physicochemical properties were as follows: oxidation-reduction potential ranged from -173 to 466 millivolts, dissolved oxygen ranged from less than 0.1 to 4.4 milligrams per liter, pH ranged from 7.2 to 7.8, specific conductance ranged from 439 to 724 microsiemens per centimeter at 25 degrees Celsius, and alkalinity ranged from 159 to 276 milligrams per liter as calcium carbonate. The largest ranges in concentration for filtered major ion constituents were obtained for cations sodium and calcium and for anions chloride and sulfate. Arsenic concentrations measured in samples from the 47 wells ranged from 1.6 to 23.5 micrograms per liter. The maximum concentration of arsenic (23.5 micrograms per liter) was measured in the source-water sample from well LJ-65-12-328. Quantifiable concentrations of barium, boron, lithium, molybdenum, and strontium were measured in all 47 filtered, source-water samples. Quantifiable concentrations of manganese were measured in 46 source-water samples, and an estimated concentration of manganese was measured in 1 sample. Chromium, iron, selenium, and vanadium were detected in 24 or more of the 47 source-water samples. Gross alpha-particle activities and beta-particle activities for all 47 samples were analyzed at 72 hours after sample collection and again at 30 days after sample collection, allowing for the measurement of the activity of short-lived isotopes. Gross alpha-particle activities reported in this report were not adjusted for activity contributions by radon or uranium and, therefore, are conservatively high estimates if compared to the U.S. Environmental Protection Agency National Primary Drinking Water Regulation for adjusted gross alpha-particle activity. The gross alpha-particle activities at 30 days in the samples ranged from R0.60 to 25.5 picocuries per liter and at 72 hours ranged from 2.58 to 39.7 picocuries per liter, and the "R" preceding the value of 0.60 picocuries per liter refers to a nondetected result less than the sample-specific critical level. Gross beta-particle activities measured at 30 days ranged from 1.17 to 14.4 picocuries per liter and at 72 hours ranged from 1.97 to 4.4 picocuries per liter. Filtered uranium was detected in quantifiable amounts in all of the 47 wells sampled. The uranium concentrations ranged from 0.03 to 42.7 micrograms per liter. One sample was analyzed for carbon-14, and the amount of modern atmospheric carbon was reported as 0.2 percent. Six source-water samples collected from municipal supply wells were analyzed for radium-226, and all of the concentrations were considered detectable concentrations (greater than their associated sample-specific critical level). Three source-water samples collected were analyzed for radon-222, and all of the concentrations were substantially greater than the associated sample-specific critical level.

Texas↗
USGS2007

Methods and data used to investigate polonium-210 as a source of excess gross-alpha radioactivity in ground water, Churchill County, Nevada

Ground water is the major source of drinking water in the Carson River Basin, California and Nevada. Previous studies have shown that uranium and gross-alpha radioactivities in ground water can be greater than U.S. Environmental Protection Agency Maximum Contaminant Levels, particularly in the Carson Desert, Churchill County, Nevada. Studies also have shown that the primary source of the gross-alpha radioactivity and alpha-emitting radionuclides in ground water is the dissolution of uranium-rich granitic rocks and basin-fill sediments that have their origins in the Sierra Nevada. However, ground water sampled from some wells in the Carson Desert had grossalpha radioactivities greater than could be accounted for by the decay of dissolved uranium. The occurrence of polonium-210 (Po-210) was hypothesized to explain the higher than expected grossalpha radioactivities. This report documents and describes the study design, field and analytical methods, and data used to determine whether Po-210 is the source of excess gross-alpha radioactivity in ground water underlying the Carson Desert in and around Fallon, Nevada. Specifically, this report presents: 1) gross alpha and uranium radioactivities for 100 wells sampled from June to September 2001; and 2) pH, dissolved oxygen, specific conductance, and Po-210 radioactivity for 25 wells sampled in April and June 2007. Results of quality-control samples for the 2007 dataset are also presented.

Open-File Report↗
USGS2009

Geochemical Analyses of Rock, Sediment, and Water from the Region In and Around the Tuba City Landfill, Tuba City, Arizona

The Tuba City Landfill (TCL) started as an unregulated waste disposal site in the 1940s and was administratively closed in 1997. Since the TCL closure, radionuclides have been detected in the shallow ground water. In 2006, the Bureau of Indian Affairs (BIA) contracted with the U.S. Geological Survey (USGS) to better understand the source of radionuclides in the ground water at the TCL compared to the surrounding region. This report summarizes those data and presents interpretations that focus on the geochemistry in the rocks and water from the Tuba City region. The TCL is sited on Navajo Sandstone above the contact with the Kayenta Formation. These formations are not rich in uranium but generally are below average crustal abundance values for uranium. Uranium ores in the area were mined nearby in the Chinle Formation and processed at the Rare Metals mill (RMM). Regional samples of rock, sediment, leachates, and water were collected in and around the TCL site and analyzed for major and minor elements, 18O, 2H, 3H, 13C, 14C,34S, 87Sr, and 234U/238U, as appropriate. Results of whole rock and sediment samples, along with leachates, suggest the Chinle Formation is a major source of uranium and other trace elements in the area. Regional water samples indicate that some of the wells within the TCL site have geochemical signatures that are different from the regional springs and surface water. The geochemistry from these TCL wells is most similar to leachates from the Chinle Formation rocks and sediments. Isotope samples do not uniquely identify TCL-derived waters, but they do provide a useful indicator for shallow compared to deep ground-water flow paths and general rock/water interaction times. Information in this report provides a comparison between the geochemistry within the TCL and in the region as a whole.

Open-File Report↗
USGS1956

Geology and ore deposits of the Monument Valley area, Apache and Navajo Counties, Arizona

In 1951 the U.S. Geological Survey undertook a program of uranium investigations in Apache and Navajo Counties, northeastern Arizona. The work had three major objectives. The first was to accumulate data basic to an understanding of the regional geology. The second was to appraise the Triassic strata as host rocks for uranium deposits, and to select areas favorable for exploration for concealed deposits. The third objective was to study the controls that influence uranium deposition and from this study, to establish guides useful in prospecting for uranium deposits.

Arizona↗
USGS1976

Geology and ore deposits of the McDermitt Caldera, Nevada-Oregon

The McDermitt caldera is a Miocene collapse structure along the Nevada-Oregon border. The oval-shaped caldera is bounded by arcuate normal faults on the north and south and by rhyolite ring domes on the west. Precollapse ash-flow tuffs exposed within the south caldera rim consist of three cooling units and are peralkaline in composition. Refractive indexes of nonhydrated glasses from basal vitrophyres of the. units range from 1.493 to 1.503 and are typical of comendites. Post-collapse intracaldera rocks consist of tuffaceous lake sediments, rhyolite flows and domes, and ash-flow tuffs. Within the caldera are the mercury mines of Bretz, Cordero, McDermitt, Opalite, and Ruja and the Moonlight uranium mine. The mercury mines are adjacent to ring fracture faults, and the uranium mine and other uranium occurrences are located within rhyolite ring domes. Fluid inclusions in quartz indicate a deposition temperature of 340?C for the uranium deposit and 200?C for the mercury deposits. The mercury deposits formed at shallow depth by replacement of lakebed sediments and volcanic rocks.

Open-File Report↗
USGS1977

Geologic interpretation of a radioactivity anomaly near the west fork of the Buckland River, western Alaska

A large part of western Alaska has been included in a uranium- thorium metallogenic province (Clark and others, 1974; Miller and Bunker, 1976; Miller, 1976) chiefly because of the occurrence of uraniferous plutonic rocks with local concentrations of uranium minerals. Recently, however, anomalous amounts of uranium and thorium have been found by the Geological Survey in volcanic and volcaniclastic rocks near the headwaters of the West Fork of the Buckland River in the central Candle quadrangle (fig. 1). This occurrence is apparently in a different geologic environment than previously noted uranium occurrences in western Alaska. An increase in radioactivity was noted in this general area and three airborne gamma-ray survey traverses, done as part of an ERDA-sponsored reconnaissance survey of western Alaska, cross the area (figs. 1, 2) and confirm the existence of a radioactivity anomaly (U.S. Energy Research and Development Administration, 1975, report GJO-1653).

Alaska↗
USGS1983

Preliminary assessment of the geochemistry and mineral favorability of the postorogenic granites of the southeastern Arabian Shield, Kingdom of Saudi Arabia

Chemical analyses of samples for 19 postorogenic plutons from the southeastern Arabian Shield show that these rocks have average potassium/rubidium ratios (162) and average rubidium/strontium ratios (11.8) characteristic of highly evolved granites. Most of the analyzed samples are peraluminous. Three plutons are physically similar in terms of shape and megascopic textural zonation to peralkaline complexes in the northeastern part of the Shield, but none of the samples from these plutons is peralkaline. However, these plutons do contain the least-evolved samples. Zinc, yttrium, uranium, thorium, and possibly copper, each occur in anomalously high concentrations in at least one pluton relative to contents typically cited for granite. The average regional concentrations of copper and zinc are anomalously high. These facts suggest at least a moderate potential for mineralization in the southeastern part of the Shield. Good correlations (r of 0.5 to 0.8) between uranium, thorium, yttrium, and rubidium and an excellent correlation (r=0.98) between uranium and radium-equivalent uranium suggest that secondary deposits of these elements are unlikely and that magmatic deposits, especially of a pegmatitic nature, are more likely. Concentrations of some major elements and several trace elements covary with sample location as measured by latitude and longitude. This fact is interpreted to reflect regional variations in the protolith that have been proposed on the basis of lead isotopic data. The chemical variations suggest a largely oceanic crustal component for granites in the southwestern part of the southeastern Shield and a largely continental crustal component to the northeast. Further quantitative analysis is recommended to verify and accurately delineate anomalous concentrations of trace elements. Trend surface analysis of all available data for postorogenic granites from the eastern Arabian Shield is suggested as a method for testing regional variations in the protolith that might control locations of highly favorable areas of ore deposition.

Open-File Report↗
USGS1994

Ground-water quality and geochemistry in Carson and Eagle Valleys, western Nevada and eastern California

Aquifers in Carson and Eagle Valleys are an important source of water for human consumption and agriculture. Concentrations of major constituents in water from the principal aquifers on the west sides of Carson and Eagle Valleys appear to be a result of natural geochemical reactions with minerals derived primarily from plutonic rocks. In general, water from principal aquifers is acceptable for drinking when compared with current (1993) Nevada State drinking-water maximum contaminant level standards. Water was collected and analyzed for all inorganic constituents for which primary or secondary drinking-water standards have been established. About 3 percent of these sites had con- stituents that exceeded one or more primary or secondary drinking-water standards have been established. About 3 percent of these sites had con- stituents that exceeded one or more primary standards and water at about 10 percent of the sites had at least one constituent that surpassed a secondary standard. Arsenic exceeded the standard in water at less than 1 percent of the principal aquifer sites; nitrate surpassed its standard in water at 3 percent of 93 sites. Water from wells in the principal aquifer with high concentrations of nitrate was in areas where septic systems are used; these concentrations indicate that contamination may be entering the wells. Concentrations of naturally occurring radionuclides in water from the principal aquifers, exceed the proposed Federal standards for some constituents, but were not found t be above current (1993) State standards. The uranium concen- trations exceeded the proposed 20 micrograms per liter Federal standard at 10 percent of the sites. Of the sites analyzed for all of the inorganic constituents with primary standards plus uranium, 15 percent exceed one or more established standards. If the proposed 20 micrograms per liter standard for uranium is applied to the sampled sites, then 23 percent would exceed the standard for uranium or some other constituent with a primary drinking water standard. This represents a 50-percent increase in the frequency of exceedance. Almost all water sampled from the principal aquifers exceeds the 300 picocuries per liter proposed standard for radon. Ground-water sampling sites with the highest radon activities in water are most commonly located in the upland aquifers in the Sierra Nevada and in the principal aquifers beneath the west sides of Carson and Eagle Valleys.

Open-File Report↗
USGS1994

Ground-water quality and geochemistry, Carson Desert, western Nevada

Aquifers in the Carson Desert are the primary source of drinking water, which is highly variable in chemical composition. In the shallow basin-fill aquifers, water chemistyr varies from a dilute calcium bicarbonate-dominated water beneath the irrigated areas to a saline sodium chloride- dominated water beneath unirrigated areas. Water samples from the shallow aquifers commonly have dissolved solids, chloride, magnesium, sulfate, arsenic, and manganese concentrations that exceed State of Nevada drinking-water standards. Water in the intermediante basin-fill aquifers is a dilute sodium bicarbonate type in the Fallon area and a distinctly more saline sodium chloride type in the Soda Lake-Upsal Hogback area. Dissolved solids, chloride, arsenic, fluoride, and manganese concen- trations commonly exceed drinking-water standards. The basalt aquifer contains a dilute sodium bicarbonate chloride water. Arsenic concentrations exceed standards in all sampled wells. The concen- trations of major constituents in ground water beneath the southern Carson Desert are the result of evapotranspiration and natural geochemical reactions with minerals derived mostly from igneous rocks. Water with higher concentrations of iron and manganese is near thermodynamic equilibrium with siderite and rhodochrosite and indicates that these elements may be limited by the solubility of their respective carbonate minerals. Naturally occurring radionuclides (uranium and radon-222) are present in ground water from the Carson Desert in concen- tratons higher than proposed drinking-water standards. High uranium concentrations in the shallow aquifers may be caused by evaporative concentration and the release of uranium during dissolution of iron and manganese oxides or the oxidation of sedimentary organic matter that typically has elevated uranium concentrations. Ground water in the Carson Desert does not appear to have be contaminated by synthetic organic chemicals.

Open-File Report↗
USGS2009

Diel Sampling of Groundwater and Surface Water for Trace Elements and Select Water-Quality Constituents at a Former Zinc Smelter Site near Hegeler, Illinois, August 1-3, 2007

Surface water can exhibit substantial diel variations in the concentration of a number of constituents. Sampling regimens that do not characterize diel variations in water quality can result in an inaccurate understanding of site conditions and of the threat posed by the site to human health and the environment. Surface- and groundwater affected by acid drainage were sampled every 60 to 90 minutes over a 48-hour period at a former zinc smelter known as the Hegeler Zinc Superfund Site, in Hegeler, Ill. Groundwater-quality data from a well at the site indicate stable, low pH, weakly oxidizing geochemical conditions in the aquifer. With the exceptions of temperature and pH, no constituents exhibited diel variations in groundwater. Variations in temperature and pH likely were not representative of conditions in the aquifer. Surface water was sampled at a site on Grape Creek. Diel variations were observed in temperature, dissolved oxygen, pH, and specific conductance, and in the concentrations of nitrite, barium, iron, lead, vanadium, and possibly uranium. Concentrations during the diel cycles varied by about an order of magnitude for nitrite and varied by about a factor of two for barium, iron, lead, vanadium, and uranium. Temperature, dissolved oxygen, specific conductance, nitrite, barium, lead, and uranium generally reached maximum values during the afternoon and minimum values during the night. Iron, vanadium, and pH generally reached minimum values during the afternoon and maximum values during the night. These variations would need to be accounted for during sampling of surface-water quality in similar hydrologic settings. The temperature variations in surface water were affected by variations in air temperature. Concentrations of dissolved oxygen were affected by variations in the intensity of photosynthetic activity and respiration. Nitrite likely was formed by the oxidation of ammonium by dissolved oxygen and degraded by its anaerobic oxidation by ammonium or as part of the decomposition of organic matter. Variations in pH were affected by the photoreduction of Fe3+ to Fe2+ and the precipitation of iron oxyhydroxides. Diel variations in concentrations of iron and vanadium were likely caused by variations in the dissolution and precipitation of iron oxyhydroxides, oxyhydroxysulfates, and hydrous sulfates, which may have been affected by in the intensity of insolation, iron photoreduction, and the concentration of dissolved oxygen. The concentrations of lead, uranium, and perhaps barium in Grape Creek may have been affected by competition for sorption sites on iron oxyhydroxides. Competition for sorption sites was likely affected by variations in pH and the concentration of Fe2+. Constituent concentrations likely also were affected by precipitation and dissolution of minerals that are sensitive to changes in pH, temperature, oxidation-reduction conditions, and biologic activity. The chemical and biologic processes that resulted in the diel variations observed in Grape Creek occurred within the surface-water column or in the underlying sediments.

Scientific Investigations Report↗