SEARCH · USGS Science

Results for “Uranium”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,189 records · Page 66Linked to original sources

USGS2023

Quality of groundwater used for domestic supply in the Modesto, Turlock, and Merced Subbasins of the San Joaquin Valley, California

Summary More than 2 million Californians rely on groundwater from privately owned domestic wells for drinking-water supply. This report summarizes a water-quality survey of domestic and small-system drinking-water supply wells in the Modesto, Turlock, and Merced subbasins of the San Joaquin Valley where more than 78,000 residents are estimated to use privately owned domestic wells. Results indicate that inorganic and organic constituents in groundwater were respectively present above regulatory (maximum contaminant level, MCL) benchmarks for public drinking-water quality in 37 percent and 9 percent of the aquifer area used for domestic drinking-water supplies (herein, “domestic groundwater resources”). The most prevalent inorganic constituents exceeding regulatory benchmarks were nitrate, uranium, and arsenic. The only organic constituents exceeding regulatory benchmarks were the fumigant constituents 1,2,3-trichloropropane (1,2,3-TCP) and 1,2-dibromo-3-chloropropane (DBCP), but the herbicides atrazine and simazine were detected at low concentrations below one-tenth of regulatory benchmarks in 30 percent of domestic groundwater resources. Total dissolved solids (TDS) and manganese exceeded aesthetic-based (secondary maximum contaminant level [SMCL]) benchmarks for drinking water in 3 percent and 13 percent of domestic groundwater resources, respectively. Per- and polyfluoroalkyl substances (PFAS) were detected in 23 percent of domestic groundwater resources, with 4 percent exceeding California state notification or response levels for specific compounds. Total coliform bacteria were detected in 20 percent of domestic groundwater resources. Elevated concentrations of nitrate, uranium, TDS, and pesticides (fumigant constituents and herbicides) are related to agricultural land use and were typically present at shallow depths up to 75 meters below land surface. Agriculturally derived constituents were detected in wells screened below the Corcoran Clay Member of the Tulare Formation (herein, “Corcoran Clay”) in the southeastern part of the study area, where the Corcoran Clay tends to be shallower and thinner than in areas to the northwest. Nitrate, uranium, and TDS were most prevalent in the northwest part of the study area proximal to the valley trough where soils are poorly drained and agricultural land uses are predominantly grain, alfalfa, and dairy farms. Pesticides tended to occur in groundwater below coarse-grained surficial deposits and within a northwest to southeast trending band along the eastern extent of the Corcoran Clay that typically demarcates the western extent of well-drained soils associated with perennial orchard crops. Elevated concentrations of arsenic tended to occur west of this band in reducing groundwater but also sometimes co-occurred with elevated nitrate in oxic groundwater, most likely because of geochemical conditions in agriculturally affected groundwater that can enhance the mobility of arsenic from aquifer sediments.

California↗

USGS1975

Depositional environments and paleocurrent directions in the Precambrian Moeda Formation, Minas Gerais, Brazil

The middle Precambrian Moeda Formation of Minas Gerais, Brazil, contains uranium and other minerals believed to be of detrital origin. Two areas of anomalously high concentrations of uranium have been discovered in conglomeratic zones that are interpreted as paleochannels. Because the distribution of uranium is believed to be controlled at least in part by sedimentation, a reconnaissance study was undertaken to assess the depositional environment and sediment dispersal pattern of the Moeda Formation.

Minas Gerais↗

USGS1978

Mineral potential of altered rocks near Blawn Mountain, Wah Wah Range, Utah

A mineralized area near Blawn Mountain in the southern Wah Wah Range has potential for deposits of lithophile metals, including uranium, tin, molybdenum, and beryllium. An area of iron oxide, alunite, and kaolinite alteration in rhyolite on Blawn Mountain overlaps southward with an area of fluorite, montmorillonite, and illite alteration in rhyolite and breccia near the Staats mine. The area on Blawn Mountain is largely depleted of metals other than iron, but the area near the Staats mine has produced some fluorspar and uranium and has anomalous amounts of tin, molybdenum, and beryllium in altered rock. Topaz rhyolites near the Staats mine and on The Tetons are similar to those in the Thomas Range of Utah, which are associated with deposits of fluorspar, uranium, and beryllium. Unmineralized topaz rhyolite in the Wah Wah Range contains anomalous traces of Be, Ga, Li, Mo, Nb, and Sn. Extensive areas of jasperoid with very low trace metal contents are associated with the areas of mineralization and alteration. The age of alteration and mineralization in the southern Wah Wah Range can De inferred from the age of host rocks. The rhyolite of Blawn Mountain, which is the host for alunite and kaolinite, is dated as 30.7?1.5 m.y. old. The intrusive topaz rhyolite of the Staats mine area, which with its altered breccia zone is the host and probable source of fluorine and lithophile metals, is 19.7?0.8 m.y. old. The overlap of both kaolinite and montmorillonite in altered breccia along the north side of the intrusive topaz rhyolite suggests that all of the alteration and mineralization may be younger than 19.7?0.8 m.y.

Open-File Report↗

USGS1978

A summary of niobium and rare earth localities from Ha'il and other areas in western Saudi Arabia: a preliminary study

Investigations in 1965 located veins containing radioactive material in the Halaban Group on the east side of a granite pluton at Jabal Aja near Ha'il. Later study extended the known area of radioactivity to a total length of about 30 km. Mineralogic studies indicated that the samples were low in uranium and that the radioactivity was due principally to thorium in niobium-bearing minerals. Two samples were reexamined to identify the sources of radioactivity, but X-ray and alpha plate studies did not reveal the radioactive minerals, even though uranium mineralization was indicated by the alpha plates. Further sampling is suggested to isolate the sources of radioactivity. This study indicates that niobium occurrences are related to alkaline intrusives in many areas of western Saudi Arabia. These areas should be investigated for their possible niobium and rare earth contents; their uranium content is apparently too low to be of economic interest.

Open-File Report↗

USGS2014

A deposit model for carbonatite and peralkaline intrusion-related rare earth element deposits

Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. A wide variety of other commodities have been exploited from carbonatites and alkaline igneous rocks including niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other elements enriched in these deposits include manganese, strontium, tantalum, thorium, vanadium, and uranium. Carbonatite and peralkaline intrusion-related rare earth element deposits are presented together in this report because of the spatial, and potentially genetic, association between carbonatite and alkaline rocks. Although these rock types occur together at many locations, carbonatite and peralkaline intrusion-related rare earth element deposits are not generally found together. Carbonatite hosted rare earth element deposits are found throughout the world, but currently only five are being mined for rare earth elements: Bayan Obo, Daluxiang, Maoniuping, and Weishan deposits in China and the Mountain Pass deposit in California, United States. These deposits are enriched in light rare earth elements, including lanthanum, cerium, praseodynium, and neodynium. The principal rare earth element-minerals associated with carbonatites are fluocarbonates (bastnäsite, parisite, and synchysite), hydrated carbonates (ancylite), and phosphates (monazite) with bastnäsite being the primary ore mineral. Calcite and dolomite are the primary gangue minerals. At present, the only rare earth element production from a peralkaline intrusion-related deposit is as a byproduct commodity at the Lovozero deposit in Russia. Important rare earth element minerals found in various deposits include apatite, eudialyte, loparite, gittinsite, xenotime, gadolinite, monazite, bastnäsite, kainosite, mosandrite, britholite, allanite, fergusonite, and zircon, and these minerals tend to be enriched in heavy rare earth elements. Carbonatite and alkaline intrusive complexes are derived from partial melts of mantle material, and neodymium isotopic data are consistent with the rare earth elements being derived from the parental magma. Deposits and these associated rock types tend to occur within stable continental tectonic units, in areas defined as shields, cratons, and crystalline blocks; they are generally associated with intracontinental rift and fault systems. Protracted fractional crystallization of the magma leads to enrichment in rare earth elements and other incompatible elements. Rare earth element mineralization associated with carbonatites can occur as either primary mineral phases or as mineralization associated with late stage orthomagmatic fluids. Rare earth element mineralization associated with alkaline intrusive complexes may occur as primary phases in magmatic layered complexes or as late-stage dikes and veins. The greatest environmental challenges associated with carbonatite and peralkaline intrusion-related rare earth element deposits center on the associated uranium and thorium. Considerable uncertainty exists around the toxicity of rare earth elements and warrants further investigation. The acid-generating potential of carbonatites and peralkaline intrusion-related deposits is low due to the dominance of carbonate minerals in carbonatite deposits, the presence of feldspars and minor calcite within the alkaline intrusion deposits, and only minor quantities of potentially acid-generating sulfides. Therefore, acid-drainage issues are not likely to be a major concern associated with these deposits. Uranium has the potential to be recovered as a byproduct, which would mitigate some of its environmental effects. However, thorium will likely remain a waste-stream product that will require management since progress is not being made towards the development of thorium-based nuclear reactors in the United States or other large scale commercial uses. Because some deposits are rich in fluorine and beryllium, these elements may be of environmental concern in certain locations.

Scientific Investigations Report↗

USGS2013

Status and understanding of groundwater quality in the Madera, Chowchilla Study Unit, 2008: California GAMA Priority Basin Project

Groundwater quality in the approximately 860-square-mile Madera and Chowchilla Subbasins (Madera-Chowchilla study unit) of the San Joaquin Valley Basin was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in California's Central Valley region in parts of Madera, Merced, and Fresno Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The Project was designed to provide statistically robust assessments of untreated groundwater quality within the primary aquifer systems in California. The primary aquifer system within each study unit is defined by the depth of the perforated or open intervals of the wells listed in the California Department of Public Health (CDPH) database of wells used for municipal and community drinking-water supply. The quality of groundwater in shallower or deeper water-bearing zones may differ from that in the primary aquifer system; shallower groundwater may be more vulnerable to contamination from the surface. The assessments for the Madera-Chowchilla study unit were based on water-quality and ancillary data collected by the USGS from 35 wells during April-May 2008 and water-quality data reported in the CDPH database. Two types of assessments were made: (1) status , assessment of the current quality of the groundwater resource, and (2) understanding , identification of natural factors and human activities affecting groundwater quality. The primary aquifer system is represented by the grid wells, of which 90 percent (%) had depths that ranged from about 200 to 800 feet (ft) below land surface and had depths to the top of perforations that ranged from about 140 to 400 ft below land surface. Relative-concentrations (sample concentrations divided by benchmark concentrations) were used for evaluating groundwater quality for those constituents that have Federal or California regulatory or non-regulatory benchmarks for drinking-water quality. A relative-concentration (RC) greater than 1.0 indicates a concentration above a benchmark. RCs for organic constituents (volatile organic compounds and pesticides) and special-interest constituents (perchlorate) were classified as "high" (RC is greater than 1.0), "moderate" (RC is less than or equal to 1.0 and greater than 0.1), or "low" (RC is less than or equal to 0.1). For inorganic constituents (major and minor ions, trace elements, nutrients, and radioactive constituents), the boundary between low and moderate RCs was set at 0.5. The assessments characterize untreated groundwater quality, not the quality of treated drinking water delivered to consumers by water purveyors; drinking-water benchmarks, and thus relative-concentrations, are used to provide context for the concentrations of constituents measured in groundwater. Aquifer-scale proportion was used in the status assessment as the primary metric for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the percentage of the area of the primary aquifer system with RCs greater than 1.0 for a particular constituent or class of constituents; moderate and low aquifer-scale proportions are defined as the percentages of the area of the primary aquifer system with moderate and low RCs, respectively. Percentages are based on an areal, rather than a volumetric basis. Two statistical approaches--grid-based, which used one value per grid cell, and spatially weighted, which used multiple values per grid cell--were used to calculate aquifer-scale proportions for individual constituents and classes of constituents. The spatially weighted estimates of high aquifer-scale proportions were within the 90% confidence intervals of the grid-based estimates for all constituents except iron. The status assessment showed that inorganic constituents had greater high and moderate aquifer-scale proportions in the Madera-Chowchilla study unit than did organic constituents. RCs for inorganic constituents with health-based benchmarks were high in 37% of the primary aquifer system, moderate in 30%, and low in 33%. The inorganic constituents contributing most to the high aquifer-scale proportion were arsenic (13%), uranium (17%), gross alpha particle activity (20%), nitrate (6.7%), and vanadium (3.3%). RCs for inorganic constituents with non-health-based benchmarks were high in 6.7% of the primary aquifer system, and the constituent contributing most to the high aquifer-scale proportion was total dissolved solids (TDS). RCs for organic constituents with health-based benchmarks were high in 10% of the primary aquifer system, moderate in 3.3%, and low in 40%; organic constituents were not detected in 47% of the primary aquifer system. The fumigant 1,2-dibromo-3-chloropropane (DBCP) was the only organic constituent detected at high RCs. Seven organic constituents were detected in 10% or more of the primary aquifer system: DBCP; the fumigant additive 1,2,3-trichloropropane; the herbicides simazine, atrazine, and diuron; the trihalomethane chloroform; and the solvent tetrachloroethene (PCE). RCs for the special-interest constituent perchlorate were moderate in 20% of the primary aquifer system. The second component of this study, the understanding assessment , identified the natural and human factors that may affect groundwater quality by evaluating statistical correlations between water-quality constituents and potential explanatory factors, such as land use, position relative to important geologic features, groundwater age, well depth, and geochemical conditions in the aquifer. Results of the statistical evaluations were used to explain the distribution of constituents in the study unit. Depth to the top of perforations in the well and groundwater age were the most important explanatory factors for many constituents. High and moderate RCs of nitrate, uranium, and TDS and the presence of herbicides, trihalomethanes, and solvents were all associated with depths to the top of perforations less than 235 ft and modern- and mixed-age groundwater. Positive correlations between uranium, bicarbonate, TDS, and the proportion of calcium and magnesium in the total cations suggest that downward movement of recharge from irrigation water contributed to the elevated concentrations of these constituents in the primary aquifer system. High and moderate RCs of arsenic were associated with depths to the top of perforations greater than 235 ft, mixed- and pre-modern-age groundwater, and location in sediments from the Chowchilla River alluvial fan, suggesting that increased residence time and appropriate aquifer materials were needed for arsenic to accumulate in the groundwater. High and moderate RCs of fumigants were associated with depths to the top of perforations of less than 235 ft and location south of the city of Madera; low RCs of fumigants were detected in wells dispersed across the study unit with a range of depths to top of perforations.

California↗

USGS2014

Stream-water and groundwater quality in and near the Citizen Potawatomi Nation Tribal Jurisdictional Area, Pottawatomie County, Oklahoma, 2012-13

The Citizen Potawatomi Nation needs to characterize their existing surface-water and groundwater resources in and near their tribal jurisdictional area to complete a water-resource management plan. Water resources in this area include surface water from the North Canadian and Little Rivers and groundwater from the terrace and alluvial aquifers and underlying bedrock aquifers. To assist in this effort, the U.S. Geological Survey (USGS), in cooperation with the Citizen Potawatomi Nation, collected water-quality samples at 4 sites on 3 streams and from 30 wells during 2012 and 2013 in and near the Citizen Potawatomi Nation Tribal Jurisdictional Area in central Oklahoma. Stream samples were collected eight times on the North Canadian River at the upstream USGS streamflow-gaging station North Canadian River near Harrah, Okla. (07241550); at the downstream USGS streamflow-gaging station North Canadian River at Shawnee, Okla. (07241800); and on the Little River at the USGS streamflow-gaging station Little River near Tecumseh, Okla., (07230500). Stream samples also were collected three times at an ungaged site, Deer Creek near McLoud, Okla. (07241590). Water properties were measured, and water samples were analyzed for concentrations of major ions, nutrients, trace elements, counts of fecal-indicator bacteria, and 69 organic compounds. The highest concentrations of dissolved solids and chlorides were measured in stream-water samples collected at the Little River near Tecumseh station. The Secondary Maximum Contaminant Level (SMCL) for dissolved solids in drinking water of 500 milligrams per liter (mg/L) was exceeded in 7 of 8 stream-water samples, with a median concentration of 844 mg/L at that station. The 250-mg/L SMCL for chloride was exceeded in 5 of the 8 stream-water samples collected at that station. Median concentrations of total dissolved nitrogen were about an order of magnitude higher in stream-water samples collected at the two stations on the North Canadian River than concentrations in stream-water samples collected at the Little River near Tecumseh station and the Deer Creek site. Median concentrations of total dissolved nitrogen were 4.36 and 2.89 mg/L in stream-water samples collected at the two North Canadian River stations, 0.35 mg/L in stream-water samples collected at the Little River near Tecumseh station, and 0.76 mg/L in stream-water samples collected at the Deer Creek site. Similar to nitrogen, median concentrations of total dissolved phosphorus were higher by about two orders of magnitude in stream-water samples collected at the two stations on the North Canadian River than concentrations in stream-water samples collected at the Little River near Tecumseh station and the Deer Creek site. Median concentrations of total dissolved phosphorus were 1.05 and 0.805 mg/L in stream-water samples collected at the two North Canadian River stations, 0.007 mg/L in stream-water samples collected at the Little River near Tecumseh station, and 0.032 mg/L from the Deer Creek site. Dissolved concentrations of total nitrogen, nitrate-nitrogen, orthophosphorus, and total phosphorus were highest in stream-water samples collected at the two North Canadian River stations at low streamflows, indicating that wastewater effluent may have been a notable source of these nutrients. Concentrations of most trace elements increased with increasing streamflow in stream-water samples collected at the two North Canadian River stations, indicating that most trace elements are washed into the river by runoff from the land surface or resuspended from streambed sediments. In general, most trace-element concentrations were below respective Maximum Contaminant Levels (MCLs) for public drinking-water supplies, except for one stream-water sample with an arsenic concentration of 10.1 micrograms per liter (µg/L) collected from the North Canadian River and one stream-water sample with a barium concentration of 2,690 µg/L collected from the Little River. At least one stream-water sample from each of the four stream sites sampled in this study contained a lead concentration exceeding the SMCL of 15 µg/L. All of these samples were collected during high streamflows. A greater number of organic compounds were detected in stream-water samples collected at the two stations on the North Canadian River than in stream-water samples collected at the Tecumseh station and Deer Creek site. In the 8 stream-water samples collected at the upstream Harrah station, 213 detections of organic compounds were measured, whereas in 8 samples collected at the downstream Shawnee station, 203 detections of organic compounds were measured. In contrast, 59 detections of organic compounds were measured in the 8 stream-water samples collected at the Tecumseh station, and 25 detections of organic compounds were measured in the 3 stream-water samples collected at the Deer Creek site; however, the 8 detections of 7 organic compounds in the 2 equipment-blank samples is problematic for evaluating these data, especially for the Deer Creek and Little River samples because of the comparatively low detection frequency and should be taken into consideration when evaluating these results. Groundwater samples also were collected once from 30 wells producing water from the Garber-Wellington aquifer; Admire, Chase, and Council Grove Groups; the Vanoss Formation; and the terrace and alluvial aquifers along the North Canadian River. Water properties were measured, and samples were analyzed for concentrations of major ions, nutrients, trace elements, and selected radionuclides in groundwater. Of 30 wells sampled for this study, 26 were completed in bedrock aquifers, and 4 were completed in terrace and alluvial aquifers. In general, groundwater in the study area is very hard, with a median concentration of 180 mg/L as calcium carbonate in water samples collected from the 30 wells. Concentrations of sulfate exceeded the 250-mg/L SMCL in two groundwater samples, and dissolved solids concentrations exceeded the 500-mg/L SMCL in nine groundwater samples. Trace-element concentrations did not exceed respective MCLs in the 30 groundwater samples collected for this study. Concentrations of the radionuclide uranium ranged from 0.03 to 79.5 µg/L, with a median concentration of 1.9 µg/L in the 30 groundwater samples collected. Two of the groundwater samples collected for this study had uranium concentrations exceeding the MCL of 30 µg/L, with concentrations of 79.5 and 31.1 µg/L. Generally, uranium concentrations were highest in water samples collected from wells completed in the Wellington Formation and the Chase, Council Grove, and Admire Groups in the southern and eastern parts of the study area.

Oklahoma↗

USGS2015

Status and understanding of groundwater quality in the Cascade Range and Modoc Plateau study unit, 2010: California GAMA Priority Basin Project

Groundwater quality in the Cascade Range and Modoc Plateau study unit was investigated as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project. The study was designed to provide a statistically unbiased assessment of untreated groundwater quality in the primary aquifer system. The depth of the primary aquifer system for the Cascade Range and Modoc Plateau study unit was delineated by the depths of the screened or open intervals of wells in the State of California’s database of public-supply wells. Two types of assessments were made: a status assessment that described the current quality of the groundwater resource, and an understanding assessment that made evaluations of relations between groundwater quality and potential explanatory factors representing characteristics of the primary aquifer system. The assessments characterize the quality of untreated groundwater, not the quality of treated drinking water delivered to consumers by water distributors. The status assessment was based on water-quality data collected in 2010 by the U.S. Geological Survey from 90 wells and springs (USGS-grid wells) and on water-quality data compiled from the State of California’s regulatory compliance database for samples collected from 240 public-supply wells between September 2007 and September 2010. To provide context, the water-quality data discussed in this report were compared to California and Federal drinking-water regulatory and non-regulatory benchmarks for treated drinking water. Groundwater quality is defined in terms of relative concentrations (RCs), which are calculated by dividing the concentration of a constituent in groundwater by the concentration of the benchmark for that constituent. The RCs for inorganic constituents (major ions, trace elements, nutrients, and radioactive constituents) were classified as “high” (the RC is greater than 1.0, indicating that the concentration is above the benchmark), “moderate” (the RC is from 1.0 to greater than 0.5), or “low” (the RC is less than or equal to 0.5). For organic constituents (volatile organic compounds and pesticides) and special-interest constituents (perchlorate), the boundary between moderate and low RCs was set at 0.1. All benchmarks used for organic constituents were health-based. For inorganic constituents, health-based and aesthetic-based benchmarks were used. Constituents without benchmarks were not considered in the status assessment . The primary metric used for quantifying regional-scale groundwater quality was the aquifer-scale proportion—the areal percentages of the primary aquifer system with high, moderate, and low RCs for a given constituent or class of constituents. The study unit was divided into six study areas on the basis of geologic differences (Eastside Sacramento Valley, Honey Lake Valley groundwater basin, Cascade Range and Modoc Plateau Low Use Basins, Quaternary Volcanic Areas, Shasta Valley and Mount Shasta Volcanic Area, and Tertiary Volcanic Areas), and each study area was divided into equal-area grid cells. Aquifer-scale proportions were calculated for individual constituents and constituent classes for each of the six study areas and for the study unit as a whole by using grid-based (one well per cell) and spatially weighted (many wells per cell) statistical methods. The status assessment showed that inorganic constituents were present at high and moderate RCs in greater proportions of the Cascade Range and Modoc Plateau study unit than were organic constituents. One or more inorganic constituents with health-based benchmarks were present at high RCs in 9.4 percent, and at moderate RCs in 14.7 percent of the primary aquifer system. Arsenic was present at high RCs in approximately 3 percent of the primary aquifer system; boron, molybdenum, uranium, and vanadium each were present at high RCs in approximately 2 percent of the primary aquifer system. One or more inorganic constituents with aesthetic-based benchmarks were present at high RCs in 15.1 percent of the primary aquifer system and at moderate RCs in 4.9 percent. Manganese, iron, and total dissolved solids were present at high RCs in approximately 12 percent, 5 percent, and 2 percent, respectively, of the primary aquifer system. Organic constituents were not detected at high or moderate RCs in the primary aquifer system, and one or more organic constituents were detected at low RCs in approximately 40 percent of the primary aquifer system. Two classes of organic constituents were detected in more than 10 percent of the primary aquifer system: trihalomethanes (chloroform only) and herbicides. The special interest constituent perchlorate was not detected at high RCs, but was detected at moderate RCs in approximately 2 percent of the primary aquifer system. The understanding assessment relied on statistical tests to evaluate relations between concentrations of constituents and values of potential explanatory factors representing geology, land use, well construction, hydrologic conditions, groundwater age, and geochemical conditions. The majority of the high and moderate RCs of arsenic, boron, molybdenum, uranium, and total dissolved solids were in samples from the Honey Lake Valley groundwater basin study area. Groundwater mixing with hydrothermal fluids present in the study area, evaporative concentration of groundwater in the Honey Lake playa, presence of uranium-bearing sediment derived from the adjacent Sierra Nevada, and release of arsenic and other trace elements from sediments under high pH and low dissolved oxygen conditions all appeared to contribute to these elevated concentrations. Thermal springs are in many parts of the Cascade Range and Modoc Plateau study unit and could account for locally elevated concentrations of arsenic, boron, molybdenum, and total dissolved solids in samples from the other study areas. Vanadium concentrations were greater in oxic samples than in anoxic samples, but were not correlated with pH, contrary to expectations from previous studies. Organic constituents were not detected at high or moderate RCs, and the occurrence of low organic constituents at low RCs ranged from 27 percent to 73 percent of the primary aquifers system in the six study areas. The Shasta Valley and Mount Shasta Volcanic study area had significantly greater occurrence of low RCs of herbicides compared to all of the other study areas, which could reflect the greater prevalence of modern groundwater in the Shasta Valley and Mount Shasta Volcanic study area and the presence of potential sources of herbicides, including applications to timberlands and roadside rights-of-way. The Eastside Sacramento Valley study area had the greatest occurrence of low concentrations of chloroform, and chloroform occurrence was most strongly associated with the combination of septic-tank density greater than two tanks per square kilometer and urban land use greater than 10 percent within a radius of 500 meters of the well. These conditions were most prevalent in the Eastside Sacramento Valley study area. The detection frequency of low concentrations of perchlorate was consistent with the probability of occurrence expected under natural conditions, except in the Eastside Sacramento Valley study area, where detection frequencies were much higher than expected and could not be explained by known anthropogenic sources of perchlorate.

California↗

USGS2016

Arsenic and radionuclide occurrence and relation to geochemistry in groundwater of the Gulf Coast Aquifer System in Houston, Texas, 2007–11

The U.S. Geological Survey (USGS), in cooperation with the City of Houston, began a study in 2007 to determine concentrations, spatial extent, and associated geochemical conditions that might be conducive for mobility and transport of selected naturally occurring trace elements and radionuclides in the Gulf Coast aquifer system in Houston, Texas. Water samples were collected from 91 municipal supply wells completed in the Evangeline and Chicot aquifers of the Gulf Coast aquifer system in northeastern, northwestern, and southwestern Houston; hereinafter referred to as northeast, northwest and southwest Houston areas. Wells were sampled in three phases: (1) 28 municipal supply wells were sampled during 2007–8, (2) 60 municipal supply wells during 2010, and (3) 3 municipal supply wells during December 2011. During each phase of sampling, samples were analyzed for major ions, selected trace elements, and radionuclides. At a subset of wells, concentrations of arsenic species and other radionuclides (carbon-14, radium-226, radium-228, radon-222, and tritium) also were analyzed. Selected physicochemical properties were measured in the field at the time each sample was collected, and oxidation-reduction potential and unfiltered sulfides also were measured at selected wells. The source-water (the raw, ambient water withdrawn from municipal supply wells prior to water treatment) samples were collected for assessment of aquifer conditions in order to provide community water-system operators information that could be important when they make decisions about which treatment processes to apply before distributing finished drinking water. Geochemical conditions of groundwater of the Gulf Coast aquifer system are suitable in some instances for release of arsenic and radionuclides from aquifer materials. Recent changes to the U.S. Environmental Protection Agency (EPA) primary drinking-water regulations for arsenic and a selected number of natural radionuclides have highlighted the necessity for municipal supply system managers to be aware of the occurrence and distribution of these constituents in their source water. Concentrations of arsenic ranged from 0.58 to 23.5 micrograms per liter (μg/L), with relatively low median and 75th percentile concentrations (2.7 and 3.6 μg/L, respectively). The gross alpha-particle activity completed within 72 hours after sample collection ranged from R-1.1 (nondetect where the result was below the sample specific critical level) to 39.7 picocuries per liter (pCi/L), with a median of 10.3 pCi/L. After 30 days, the gross alpha-particle activities in the 91 samples ranged from R-0.94 to 25.5 pCi/L, with a median of 5.60 pCi/L. Concentrations of uranium ranged from less than 0.02 to 42.7 μg/L, with a median value of 1.69 μg/L and a 75th-percentile value of 6.48 μg/L. The maximum concentrations of radium-226 and combined radium (sum of radium-226 plus radium-228) were 4.34 pCi/L and 3.23 pCi/L, respectively. Aquifer major-ion geochemistry was characterized and shown to contain three chemical types of water as grouped by a simplified predominant cation and anion classification system: (1) calcium- bicarbonate type, (2) sodium-bicarbonate type, and (3) sodium-chloride type. Aquifer geochemistry also was characterized into four reduction-oxidation (redox) categories: (1) oxic, (2) suboxic, (3) mixed, and (4) anoxic. Within the anoxic category, groundwater was further characterized into four presumed predominant reduction processes: (1) iron or sulfate or both [Fe(III)/SO 4 ] reducing, (2) iron [Fe(III)] reducing, (3) iron and sulfate [Fe(III)-SO 4 ] reducing, or (4) methanogenic, as defined by composition of redox species. The oxic category was associated with calcium-bicarbonate-type water, and the methanogenic-anoxic process was associated exclusively with the sodium-bicarbonate-type water. The species of arsenic and the dominant radionuclide present were associated with specific redox categories. Arsenate was associated primarily with oxic water and did not exceed 3.5 µg/L, whereas arsenite was associated with iron-reducing, anoxic water samples and, at the highest concentrations, occurred in sulfate-reducing, anoxic; methanogenic-anoxic; or both water samples. Uranium was associated exclusively with the oxic water, whereas the highest concentrations of combined radium were associated with the iron-reducing, anoxic water. The gross alpha-particle activity was greatest in the oxic waters where the source of the radioactivity was the uranium. Associated geochemical conditions conducive for mobility of arsenic and radionuclides and their spatial and vertical extent in the Gulf Coast aquifer system in Houston are important aspects to the areal management of the municipal groundwater supplies in Houston. Ongoing research is seeking to define chemical or geological factors that are the optimal indicators for elevated concentrations of these naturally occurring constituents.

Texas↗

USGS2026

Status and understanding of groundwater quality in the San Joaquin Valley Kern County subbasin domestic-supply aquifer study unit, 2022—California GAMA Priority Basin Project

The quality of water accessed by domestic wells (here referred to as domestic groundwater resources) in the San Joaquin Valley Kern County subbasin (basin number 5-022.14) was assessed as part of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project (GAMA-PBP), in cooperation with the California State Water Resources Control Board. Kern County is at the southern end of the San Joaquin Valley in California, and about 30,000 residents are estimated to use privately owned domestic wells for drinking water. Domestic wells typically draw from shallower parts of the aquifer system than public-supply wells and can be more vulnerable to effects from surface activities. Kern County is host to a highly productive agricultural industry, with Bakersfield as the main urban center. The Kern River runs through Bakersfield from the southern Sierra Nevada and intersects the Kern Water Bank, one of the largest groundwater banking operations in California, at the Kern River Intertie. The section of the Kern River running through the Kern Water Bank is dry most years. Kern County also encompasses some of the most productive oil and gas basins in California, with extensive underground and surface disposal of oil-field wastewater. This study was based on data collected from 33 sites sampled by the U.S. Geological Survey for the GAMA-PBP in 2022. To provide context for the water quality assessment, measured concentrations were compared to regulatory and non-regulatory health-based and aesthetic benchmarks. A grid-based method was used to estimate the proportions of the groundwater resources used for domestic-supply wells that have water-quality constituents below (low relative concentration), approaching (moderate relative concentration), or above (high relative concentration) benchmark concentrations. At least one measured constituent with a regulatory benchmark was categorized as having a high relative concentration in 72 percent of the aquifer area used for domestic groundwater resources. Inorganic constituents were detected at high concentrations in 45 percent of the domestic groundwater resources, and the constituents detected above regulatory benchmarks were arsenic, nitrate, and uranium. At least one organic constituent was detected at high concentrations in 41 percent of the domestic groundwater resources, and the constituents exceeding regulatory benchmarks were the fumigants 1,2,3-trichloropropane (1,2,3-TCP), 1,2-dibromo-3-chloropropane (dibromochloropropane [DBCP]), 1,2-dibromoethane (EDB), and the per-and polyfluoroalkyl substance (PFAS) perfluorooctanesulfonate. The disinfection by-product chloroform, the fumigant 1,2-dichloropropane, the herbicides atrazine and hexazinone, and the herbicide degradates 2-chloro-6-ethylamino-4-amino-s-triazine, 2-chloro-4,6-diamino-s-triazine, 4-hydroxychlorothalonil, and metolachlor sulfonic acid were detected in more than 10 percent of domestic groundwater resources, but concentrations did not exceed regulatory benchmarks. Land use, groundwater age (fraction of modern water and mean age), and geochemical environment (oxic or anoxic conditions, pH, alkalinity) were associated with the distribution of high relative concentrations of inorganic and organic constituents. Young, oxygenated water is recharged along the Kern River and adjacent recharge ponds, or as irrigation water in the agricultural areas. High concentrations of nitrate and volatile organic compounds occurred in the oxic water in urban and agricultural areas. The fumigants 1,2,3-TCP, DBCP, and EDB were reported throughout the agricultural areas, whereas chloroform, tetrachloroethene, and PFAS were associated with urban land use. High uranium concentrations were associated with young, modern groundwater in agricultural areas with low pH and high bicarbonate. Total dissolved solids increased with distance from the Kern River, as the contributions of fresh, oxic water decreased. High concentrations of arsenic were present in older anoxic or alkaline groundwater away from areas of recharge. Overall, groundwater age, redox conditions, and the source of recharge as a result of different land uses contribute to large aquifer-scale portions of domestic groundwater resources that exceed health-based benchmarks for nitrate, uranium, and fumigant concentrations.

California↗

USGS1953

Radioactive deposits of Nevada

Thirty-five occurrences of radioactive rocks had been reported from Nevada prior to 1952. Twenty-five of these had been investigated by the U. S. Geological Survey and the U. S. Atomic Energy Commission. Of those investigated, uranium minerals were identified in 13; two contained a thorium mineral (monazite); the source of radioactivity on 7 properties was not ascertained; and one showed no abnormal radioactivity. Of the other reported occurrences, one is said to contain uraniferous hydrocarbons and 9 are placers containing thorian monazite. Pitchblende occurs at two localities; the East Walker River area, and the Stalin's Present prospect, where it is sparsely disseminated in tabular bodies cutting granitic rocks. Other uranium minerals found in the state include: carnotite, tyuyamunite, autunite, torbernite, gummite, uranophane, kasolite, and an unidentified mineral which may be dumontit. Monazite is the only thorium mineral of possible economic importance that has been reported. From an economic standpoint 9 only 4 of the properties examined showed reserves of uranium ore in 1952; these are: the Green Monster mine, which shipped 5 tons of ore to Marysvale, Utah, during 1951, the Majuba Hill mine, the Stalin's Present prospect, and the West Willys claim in the Washington district. Reserves of ore grade are small on all of these properties and probably cannot be developed commercially unless an ore-buying station is set up nearby. No estimate has been made of thorium reserves and no commercial deposits of thorium are known.

Nevada↗

USGS1953

Preliminary report on the Clancy Creek area, Jefferson City quadrangle, Jefferson County, Montana

Several radioactivity anomalies and secondary uranium minerals have been found in the Clancy Creek area near the northern margin of the Boulder batholith. These are principally associated with chalcedonic zones that consist of one or more discontinuous stringers and veins of cryptocrystalline silica and fine-grained quartz in silicified quartz monzonite and alaskite. Uranium ore has been produced at the W. Wilson mine from one of these vein zones, and exploration work is being done on another--the G. Washington-A. Lincoln. Some very fine-grained pyrite and minute quantities of other sulfides have been recognized in deposits of this type. At the Lone Eagle mine small amount of uranium ore has been developed along a siliceous vein that contains sooty pitchblende (?) in small irregular fractures; significant amounts of galena and sphalerite are distributed sporadically along the vein. In the Clancy Creek area, no anomalous radioactivity has been detected in the pre-batholithic volcanic rocks or in the post-batholithic dacite and andesite.

Montana↗

USGS1952

Distribution of ore deposits and spectrographic analyses of some rocks and ores on the Colorado Plateau

The geographic pattern of known igneous rocks and ore deposits on the Colorado Plateau suggests a zonal arrangement of several types of ore deposits around centers of igneous activity. Spectrographic analyses of rocks and ores on the Plateau have been obtained in an effort to determine the distribution of elements and to examine the relationships between types of ore deposits and between the ore deposits and igneous rocks. Over 170 analyses of rocks and ores are given in this report. A preliminary study of these analyses suggests that the proportion of uranium, vanadium, copper, and silver in the uranium ores varies geographically, and that the pattern of variation may be in part concentric about some of the major laccolithic intrusions. It is also suggested that the following ratios of metals contained in the uranium ores are possible guides to larger-than-average ore deposits: (1) lead/uranium greater than 1, (2) lead/zinc greater than 10, and (3) zinc/geometric mean of cobalt and nickel less than 10.

Colorado↗

USGS1954

Wall-rock control of cortain pitchblende deposits in Golden Gate Canyon, Jefferson County, Colorado

Carbonate veins cutting pre-Cambrian metamorphic rocks in Golden Gate Canyon contain pitchblende and base-metal sulfides. The veins occupy extensive faults of Laramide age but normally contain pitchblende only where the cut hornblende gneiss. At the Union Pacific prospect, which was studied in detail, pitchblende, hermatite, and some ankerite formed in advance of sulfides, except possibly for minor pyrite. Base-metal sulfides and the bulk of ankerite-calcite vein-filling were deposited after the pitchblende. Chemical analyses show a high ferrous iron content in the hornblende gneiss in contrast to low ferrous iron in the adjacent biotite gneiss. It is hypothesized that ferrous iron released by alteration of hornblende was partly oxidized to hematite by the ore-bearing solutions and, contemporaneously, uranium was reduced and deposited as pitchblende. In other veins, biotite or iron sulfides may have been similarly effective in precipitating pitchblende. Apparently both the ferrous ion and the sulfide ion can serve as reducing agents and control pitchblende deposition. It is suggested that conditions particularly favorable for uranium deposition are present where uranium-bearing solutions had access to rocks rich in ferrous iron or pre-existing sulfides.

Colorado↗

USGS1955

Geologic investigations of radioactive deposits, semiannual progress report for June 1 to November 30, 1955

This report is a statement of progress during the six-months period from June 1 to November 30, 1955 on investigations of radioactive materials in the United States and Alaska, undertaken by the U.S. Geological Survey under the sponsorship of the U.S. Atomic Energy Commission. During the period the Geological Survey's program has been directed to an increasing extent toward the understanding of geologic conditions favorable for the concentration of uranium, rather than the search for minable deposits as such. This shift in emphasis is reflected in the decreased amount of exploration drilling during the period, and the accompanying increase in geologic programs of a long-range nature. The program is now directed toward a comprehensive understanding of the many factors involved in uranium geology, and the publication of reports that will make available information on all phases of the uranium program. Many investigations have progressed to the point where final reports are in preparation for future publication with the permission of the Atomic Energy Commission; for other investigations of a continuing nature it will be several years before final reports can be prepared. Formal publications (as distinguished from administrative Trace Elements Reports) published during the period include 10 Geological Survey Bulletins or Bulletin Chapters; 116 Geological Survey maps; 15 reports published in scientific journals; seven Trace Elements Reports sent to the Technical Information Service of the Atomic Energy Commission for distribution and sale to the public; and four Trace Elements reports placed on open file. In addition, a large number •of papers by geologists in the program were presented before scientific societies, and the 61 papers prepared for the United Nations International Conference .on the Peaceful Uses of Atomic Energy during the preceding report period were published by the United Nations.

Trace Elements Investigations↗

USGS1958

Airborne radioactivity surveys in geologic exploration

The value of airborne radioactivity surveys in guiding uranium exploration has been well established. Recent improvements in circuitry and development of semiquantitative analytical techniques permit a more comprehensive evaluation of the geologic distribution of radioactive materials that may prove useful in exploration for other minerals and in regional geologic studies. It is shown that placer deposits of heavy minerals can be detected from the air, and that the geometric configuration and average grade of the surficial part of the deposit can be approximated. Uranium-bearing phosphorite deposits may be similarly evaluated. Airborne surveys over the Coastal Plain area, Texas, show that the radioactivity profiles in some instances reflect the lithologic character of the underlying rocks. The sandstones are generally low in radioactivity (≈ 10 ppm equivalent uranium), the clays and tuffaceous rocks relatively higher. The intrinsic radioactivity of some lithologic units is sufficiently uniform and distinctive in character to permit their identification and lateral correlation on the airborne survey records. The results suggest that airborne surveys may thereby provide useful guidance in delineating lithologic continuity where the geology is poorly known or obscured.

Trace Elements Investigations↗

USGS1957

Uraniferous coal and carbonaceous shale in northeast Parana, Brazil

Uraniferous coal has been found in northeast Parana, Brazil, in the Rio Bonito formation of Pennsylvanian age. In the majority of coal samples taken the uranium oxide content ranges from 0.005 to 0.030 percent, but selected screened samples have contained as much as 0.445 percent uranium oxide. The sampled thickness of the coal seam ranges from 17 to 54 centimeters and averages 31 centimeters. Channel samples across the entire thickness of the coal zone were taken in two places. All other samples were taken as grab samples from either mine waste dumps or coal zones that had high radioactivity. Sufficient information is not yet available to justify any detailed considerations of such features as geologic distribution, mode of occurrence, and radioactive equilibrium conditions of the uranium in the coal.

Trace Elements Memorandum↗

USGS1952

Results of reconnaissance for uraniferous coal, lignite, and carbonaceous shale in western Montana

A reconnaissance search for uraniferous lignite and carbonaceous shale was made in western Montana and adjacent parts of Idaho during the summer of 1951. Particular emphasis in the examination was placed on coal and carbonaceous shale associated with volcanic rocks, as volcanic rocks in many area appear to have released uranium to circulating ground water from which it was concentrated in carbonaceous material. Twenty-two area in Montana and one area of Idaho were examine. The coal in five of these area is of Cretaceous age. The coal and carbonaceous shale in the remaining 18 area occur in Tertiary "lake-bed" deposits of Oligocene and younger age. Both the Cretaceous and Tertiary coal and carbonaceous shale are associated with contemporaneous or younger volcanic rocks and pyroclastic sequences. A sample of carbonaceous shale from the Prickly Pear Valley northeast of Helena, Montana, contained 0.013 percent uranium. A sample of carbonaceous shale from the Flint Creek Valley southwest of Drummond, Montana, contained 0.006 percent uranium. All other samples of both Cretaceous and Tertiary coal and carbonaceous shale were essentially non-radioactive. No further work is planned on the Cretaceous and Tertiary coal and carbonaceous shale in western Montana. A few localities in Idaho will be visited in the course of other work.

Idaho;Montana↗