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At least 1,657 records · Page 92Linked to original sources
USGS2001

An estimate of chemical loads from ground water to the Grand Calumet River and Indiana Harbor Canal, northwestern Indiana

Chemical loads from ground water to the Grand Calumet River and the Indiana Harbor Canal in northwestern Indiana were estimated to aid in determining the total maximum daily load. Data from two previous studies, completed in 1987 and 1993, were used to compute loads. The first study included a ground-water-flow model. Results from this model were used to determine ground-water fluxes to eight distinct reaches of the Grand Calumet River and the Indiana Harbor Canal at assumed horizontal hydraulic conductivities of 50 and 100 feet per day. In addition, water quality data collected during the first study and a second study that further described the quality of water from wells screened in the Calumet aquifer, were used with the ground-water fluxes to compute estimates of chemical loads for selected constituents contributing to the Grand Calumet River and Indiana Harbor Canal. Constituents included trace elements, polychlorinated biphenyls, pesticides, polynuclear aromatic hydrocarbons, and selected general chemistry properties. Total dissolved solids, sulfate, chloride, and dissolved ammonia as nitrogen had the largest estimated loads to the Grand Calumet River and the Indiana Harbor Canal for any river reach. The estimated loads for total dissolved solids ranged from 239 to 12,800 kilograms per day. Dissolved iron had the largest estimated load for the trace elements and exceeded 1 kilogram per day for all river reaches for which data were available. The majority of ground-water concentrations for polychlorinated biphenyls, pesticides, and polynuclear aromatic hydrocarbons were reported as less than the method reporting limit, resulting in small computed loads to the river and canal.

Indiana↗
USGS2017

Design and methods of the Midwest Stream Quality Assessment (MSQA), 2013

During 2013, the U.S. Geological Survey (USGS) National Water-Quality Assessment Project (NAWQA), in collaboration with the USGS Columbia Environmental Research Center, the U.S. Environmental Protection Agency (EPA) National Rivers and Streams Assessment (NRSA), and the EPA Office of Pesticide Programs assessed stream quality across the Midwestern United States. This Midwest Stream Quality Assessment (MSQA) simultaneously characterized watershed and stream-reach water-quality stressors along with instream biological conditions, to better understand regional stressor-effects relations. The MSQA design focused on effects from the widespread agriculture in the region and urban development because of their importance as ecological stressors of particular concern to Midwest region resource managers. A combined random stratified selection and a targeted selection based on land-use data were used to identify and select sites representing gradients in agricultural intensity across the region. During a 14-week period from May through August 2013, 100 sites were selected and sampled 12 times for contaminants, nutrients, and sediment. This 14-week water-quality “index” period culminated with an ecological survey of habitat, periphyton, benthic macroinvertebrates, and fish at all sites. Sediment was collected during the ecological survey for analysis of sediment chemistry and toxicity testing. Of the 100 sites, 50 were selected for the MSQA random stratified group from 154 NRSA sites planned for the region, and the other 50 MSQA sites were selected as targeted sites to more evenly cover agricultural and urban stressor gradients in the study area. Of the 50 targeted sites, 12 were in urbanized watersheds and 21 represented “good” biological conditions or “least disturbed” conditions. The remaining 17 targeted sites were selected to improve coverage of the agricultural intensity gradient or because of historical data collection to provide temporal context for the study. This report provides a detailed description of the MSQA study components, including surveys of ecological conditions, routine water sampling, deployment of passive polar organic compound integrative samplers, and stream sediment sampling at all sites. Component studies that were completed to provide finer scale temporal data or more extensive analysis at selected sites, included continuous water-quality monitoring, daily pesticide sampling, laboratory and in-stream water toxicity testing efforts, and deployment of passive suspended-sediment samplers.

Illinois, Indiana, Iowa, Kansas, Kentucky, Michiga↗
USGS2003

Changes in streamflow and summary of major-ion chemistry and loads in the North Fork Red River basin upstream from Lake Altus, northwestern Texas and western Oklahoma, 1945-1999

Upstream from Lake Altus, the North Fork Red River drains an area of 2,515 square miles. The quantity and quality of surface water are major concerns at Lake Altus, and water-resource managers and consumers need historical information to make informed decisions about future development. The Lugert-Altus Irrigation District relies on withdrawals from the lake to sustain nearly 46,000 acres of agricultural land. Kendall's tau tests of precipitation data indicated no statistically significant trend over the entire 100 years of available record. However, a significant increase in precipitation occurred in the last 51 years. Four streamflow-gaging stations with more than 10 years of record were maintained in the basin. These stations recorded no significant trends in annual streamflow volume. Two stations, however, had significant increasing trends in the base-flow index, and three had significant decreasing trends in annual peak flows. Major-ion chemistry in the North Fork Red River is closely related to the chemical composition of the underlying bedrock. Two main lithologies are represented in the basin upstream from Lake Altus. In the upper reaches, young and poorly consolidated sediments include a range of sizes from coarse gravel to silt and clay. Nearsurface horizons commonly are cemented as calcium carbonate caliche. Finer-grained gypsiferous sandstones and shales dominate the lower reaches of the basin. A distinct increase in dissolved solids, specifically sodium, chloride, calcium, and sulfate, occurs as the river flows over rocks that contain substantial quantities of gypsum, anhydrite, and dolomite. These natural salts are the major dissolved constituents in the North Fork Red River.

Oklahoma, Texas↗
USGS1992

Toxicity of trace element and salinity mixtures to striped bass ( Morone saxatilis ) and Daphnia magna

Acute toxicity tests with reconstituted water were conducted to investigate the relationship between water hardness, salinity, and a mixture of trace elements found in irrigation drain waters entering Stillwater Wildlife Management Area (SWMA), near Fallon, Nevada. The SWMA has been the site of many fish kills in recent years, and previous toxicity studies indicated that one drain water, Pintail Bay, was acutely toxic to organisms acclimated or cultured in fresh water or salt water. This toxicity could reflect both the ionic composition of this saline water and the presence of trace elements. The lowest water salinity tested with Daphnia magna was near the upper salinity tolerance of these organisms; therefore, we were unable to differentiate between the toxic effects of ion composition and those of trace elements. In toxicity tests conducted with striped bass ( Morone saxatilis ), we found that the extent to which salinity was lethal to striped bass depended on the ion composition of that salinity. Survival of striped bass increased as hardness increased. In addition, a trace element mixture was toxic to striped bass, even though the concentrations of individual elements were below expected acutely lethal concentrations. Although salinity is an important water quality characteristic, the ionic composition of the water must be considered when one assesses the hazard of irrigation drain waters to aquatic organisms.

Nevada↗
USGS2008

Volatile emissions and gas geochemistry of Hot Spring Basin, Yellowstone National Park, USA

We characterize and quantify volatile emissions at Hot Spring Basin (HSB), a large acid-sulfate region that lies just outside the northeastern edge of the 640 ka Yellowstone Caldera. Relative to other thermal areas in Yellowstone, HSB gases are rich in He and H2, and mildly enriched in CH4 and H2S. Gas compositions are consistent with boiling directly off a deep geothermal liquid at depth as it migrates toward the surface. This fluid, and the gases evolved from it, carries geochemical signatures of magmatic volatiles and water-rock reactions with multiple crustal sources, including limestones or quartz-rich sediments with low K/U (or 40*Ar/4*He). Variations in gas chemistry across the region reflect reservoir heterogeneity and variable degrees of boiling. Gas-geothermometer temperatures approach 300 C and suggest that the reservoir feeding HSB is one of the hottest at Yellowstone. Diffuse CO2 flux in the western basin of HSB, as measured by accumulation-chamber methods, is similar in magnitude to other acid-sulfate areas of Yellowstone and is well correlated to shallow soil temperatures. The extrapolation of diffuse CO2 fluxes across all the thermal/altered area suggests that 410 ?? 140??t d- 1 CO2 are emitted at HSB (vent emissions not included). Diffuse fluxes of H2S were measured in Yellowstone for the first time and likely exceed 2.4 t d- 1 at HSB. Comparing estimates of the total estimated diffuse H2S emission to the amount of sulfur as SO42- in streams indicates ~ 50% of the original H2S in the gas emission is lost into shallow groundwater, precipitated as native sulfur, or vented through fumaroles. We estimate the heat output of HSB as ~ 140-370 MW using CO2 as a tracer for steam condensate, but not including the contribution from fumaroles and hydrothermal vents. Overall, the diffuse heat and volatile fluxes of HSB are as great as some active volcanoes, but they are a small fraction (1-3% for CO2, 2-8% for heat) of that estimated for the entire Yellowstone system.

Journal of Volcanology and Geothermal Research↗
USGS2021

Storm-scale and seasonal dynamics of carbon export from a nested subarctic watershed underlain by permafrost

Subarctic catchments underlain by permafrost sequester a major stock of frozen organic carbon (C), which may be mobilized as the Arctic warms. Warming can impact C export from thawing soils by altering the depth and timing of runoff related to changing storm and fire regimes and altered soil thaw depths. We investigated C export in a first order headwater stream (West Twin Creek) and its receiving third order river (Beaver Creek) in interior Alaska using discrete sampling of dissolved organic and inorganic C (DOC and DIC) and 15-min collection of specific conductance (SC), fluorescent dissolved organic matter (fDOM) and water discharge (Q). Storm SC-Q relationships displayed negative slopes, indicating solute limitation and limited influence of seasonal soil thaw on storm runoff chemistry. Concurrently, fDOM-Q displayed positive slopes that decreased over the summer, indicating flushing of a limited fDOM pool. Baseflow DIC increased over the season concurrent with soil thaw, with higher DIC at the larger scale indicating greater influence of deeper, mineral-rich flow paths. Storm and seasonal trends were generally similar at both scales. The biggest difference was in fDOM, which displayed higher concentrations and slower depletion in the first order stream. Improved process understanding from this study can be used to better predict carbon export and cycling by stream networks as northern forests and arctic regions continue to warm.

Alaska↗
USGS2008

Effectiveness of an alluvial wetland on improving ground-water quality in a municipal well field, Cedar Rapids, Iowa, 1998-2006

Nutrients and pesticides are water-quality topics of concern in Iowa. Nitrate concentrations in the Cedar River and other streams in Iowa are among the highest in the Nation. A 12-mile reach of the Cedar River upstream from Cedar Rapids, Iowa, is identified on the Total Maximum Daily Load list for nitrate impairment by the U.S. Environmental Protection Agency. In addition, pesticide concentrations in water samples from alluvial aquifers in Iowa have been ranked as some of the largest in the Nation. The Cedar River, like many rivers with alluvium, affects the alluvial aquifer that is used as a municipal water supply for Cedar Rapids, Iowa. A continuing challenge for the Cedar Rapids Water Department is to provide drinking water that meets all drinking-water regulations; this is made more of a challenge because of the high (often over 10 milligrams per liter) nitrate concentrations in the Cedar River and the presence of other potential chemicals of concern, such as pesticides. An alluvial wetland proved useful in improving water quality. Samples from observation wells completed in the alluvial wetland near the municipal well field had nitrate concentrations that were four to six times lower when compared to river or upland sites; however, iron and manganese concentrations in samples from observation wells in the wetland areas were an order of magnitude higher when compared to the river or an upgradient well. Biological and chemical reduction processes were determined to mobilize inorganic constituents in accordance with physical chemistry principles. Generally, selected pesticides and two pesticide degradates of atrazine that were sampled for in alluvial wetland wells remained relatively unchanged, and indicated only a slight decrease in concentration compared to the Cedar River water samples. Pesticides were not detected above regulatory limits in any of the observation wells; however, one sample from the Cedar River had an atrazine detection at 4.5 micrograms per liter, which is above the maximum contaminant level of 3.0 micrograms per liter for drinking-water regulations for that compound. Results indicate that alluvial wetlands may provide substantial reductions of nitrate concentrations in ground water, and may be a useful strategy for the reduction of nitrate for municipal wells. Results for reducing pesticides were less dramatic than for nitrate, as pesticide concentrations were reduced slightly from the river to the wetland.

Iowa↗
USGS1988

Preliminary observations of streamflow generation during storms in a forested Piedmont watershed using temperature as a tracer

Variations in streamwater temperature at the outlet of a 41-ha forested watershed at Panola Mountain in the Georgia Piedmont indicate that the initial rapid hydrologic response is caused by a combination of groundwater discharge and channel interception of rainwater. A storm in May 1986 caused a rapid increase in discharge that was accompanied by a decrease in streamwater temperature and a rise in the water table level adjacent to the stream. The higher water table provided the hydraulic gradient necessary to increase the discharge of colder groundwater to the stream. Storms that occurred under very dry antecedent conditions in July 1986 and June 1987 caused a rapid hydrologic response but no change in water table level, indicating the response was caused by channel interception of rainwater. This conclusion was supported by increases in streamwater temperature in the June storm and by chemical changes in the July storm. When rainfall is sufficient, flow in the ephemeral part of the stream in the catchment headwaters generates a second and larger discharge peak that reflects the chemistry and temperature of runoff from a 3-ha granite outcrop in the headwaters; sulfate concentration and temperature increase and alkalinity decreases relative to prestorm conditions. The initial response, however, results from channel interception and groundwater discharge. Rapid rises in the water table level during some storms suggest that macropore flow may play a major role in the hydrologic response of the watershed to rainstorms.

Journal of Contaminant Hydrology↗
USGS2017

Predicted pH at the domestic and public supply drinking water depths, Central Valley, California

This scientific investigations map is a product of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) project modeling and mapping team. The prediction grids depicted in this map are of continuous pH and are intended to provide an understanding of groundwater-quality conditions at the domestic and public supply drinking water zones in the groundwater of the Central Valley of California. The chemical quality of groundwater and the fate of many contaminants is often influenced by pH in all aquifers. These grids are of interest to water-resource managers, water-quality researchers, and groundwater modelers concerned with the occurrence of natural and anthropogenic contaminants related to pH. In this work, the median well depth categorized as domestic supply was 30 meters below land surface, and the median well depth categorized as public supply is 100 meters below land surface. Prediction grids were created using prediction modeling methods, specifically boosted regression trees (BRT) with a Gaussian error distribution within a statistical learning framework within the computing framework of R ( http://www.r-project.org/ ). The statistical learning framework seeks to maximize the predictive performance of machine learning methods through model tuning by cross validation. The response variable was measured pH from 1,337 wells and was compiled from two sources: USGS National Water Information System (NWIS) database (all data are publicly available from the USGS: http://waterdata.usgs.gov/ca/nwis/nwis ) and the California State Water Resources Control Board Division of Drinking Water (SWRCB-DDW) database (water quality data are publicly available from the SWRCB: http://www.waterboards.ca.gov/gama/geotracker_gama.shtml ). Only wells with measured pH and well depth data were selected, and for wells with multiple records, only the most recent sample in the period 1993–2014 was used. A total of 1,003 wells (training dataset) were used to train the BRT model, and 334 wells (hold-out dataset) were used to validate the prediction model. The training r-squared was 0.70, and the root-mean-square error (RMSE) in standard pH units was 0.26. The hold-out r-squared was 0.43, and RMSE in standard pH units was 0.37. Predictor variables consisting of more than 60 variables from 7 sources were assembled to develop a model that incorporates regional-scale soil properties, soil chemistry, land use, aquifer textures, and aquifer hydrology. Previously developed Central Valley model outputs of textures (Central Valley Textural Model, CVTM; Faunt and others, 2010) and MODFLOW-simulated vertical water fluxes and predicted depth to water table (Central Valley Hydrologic Model, CVHM; Faunt, 2009) were used to represent aquifer textures and groundwater hydraulics, respectively. In this work, wells were attributed to predictor variable values in ArcGIS using a 500-meter buffer. Faunt, C.C., ed., 2009, Groundwater availability in the Central Valley aquifer, California: U.S. Geological Survey Professional Paper 1776, 225 p., accessed at https://pubs.usgs.gov/pp/1766/ . Faunt, C.C., Belitz, K., and Hanson, R.T., 2010, Development of a three-dimensional model of sedimentary texture in valley-fill deposits of Central Valley, California, USA: Hydrogeology Journal, v. 18, no. 3, p. 625–649, https://doi.org/10.1007/s10040-009-0539-7 .

California↗
USGS2025

Hydrologic variability and groundwater age of springs in eastern Oregon and northern Nevada, USA

The ecological importance of springs in semiarid regions is far greater than their small size and sparse distribution, yet little is known about the hydrologic functioning of these systems. During 2016–22, 261 springs were visited in the volcanic terrane of eastern Oregon and northern Nevada. When conditions were suitable, measurements of discharge, water temperature, and specific conductance were made, and samples for the analysis of carbon-14, tritium, and water stable isotopes (WSI) were collected. A subset of 60 springs was revisited during different seasons in the same year and during the dry season in multiple years to evaluate variability in discharge, chemistry, and groundwater age. Specific conductance and WSI varied considerably among springs across the study area but were unexpectedly stable across seasons and years at individual springs. Seasonal and interannual variability in spring discharge was related to the residence time of the discharging groundwater. Springs discharging older groundwater (10 3 –10 4 years) had significantly less variability in their discharge compared to springs discharging younger groundwater (10 0 –10 1 years). Variability among springs discharging younger groundwater included cessation of late-summer discharge at 18 % of the repeat-visit springs. A logistic regression model predicted the age of discharging spring water with 89 % accuracy using only the spring latitude, longitude, elevation, and δ 2 H value. This study framework provides a simple, inexpensive, and robust method to provisionally assess the hydrologic behavior of springs having little or no prior information in understudied, semiarid regions across the globe.

Nevada, Oregon↗
USGS2002

A Geochemical Trophic Cascade in Yellowstone's Geothermal Environments

We contrast the geochemistry of the Madison drainage, which has high concentrations of geothermal features, with the Lamar drainage of Yellowstone National Park, USA, and trace the consequences of geochemical differences through abiotic and biotic linkages in the ecosystem. Waters in the geothermal-dominated drainage contained anomalously high levels of fluoride (F) and silica (SiO 2 ). Soils, stream sediments, and surface waters that interact or mix with geothermal waters, in turn, had elevated F and SiO 2 concentrations compared to similar samples from the Lamar drainage. The geochemical differences were reflected in the chemistry of forage plants, with some plants from geothermally influenced areas containing four- to eightfold higher concentrations of F and SiO 2 than similar plants in the Lamar drainage. Geothermal heat reduced snowpack, and we found that elk (Cervus elaphus) concentrated in these refugia as snowpack increased each winter. The consequent high dietary intake of F in animals associated with the geothermal areas was confirmed by the finding that bone samples from elk living in the Madison drainage contained sixfold higher concentrations of F than samples collected from animals wintering in the Lamar drainage. High F exposure resulted in compromised dentition due to fluoride toxicosis, which was undoubtedly exacerbated by the abrasive action of silica. The consequent accelerated and aberrant tooth wear resulted in early onset of senescence, reduced life span, and an abbreviated age structure. We speculate that these altered demographics, combined with spatial heterogeneity of snowpack, will result in increased vulnerability of this large herbivore population to wolf predation and less resiliency to compensate demographically for predation.

Wyoming↗
USGS2019

Reactivity of As and U co-occurring in mine wastes in northeastern Arizona

The reactivity of co-occurring arsenic (As) and uranium (U) in mine wastes was investigated using batch reactors, microscopy, spectroscopy, and aqueous chemistry. Analyses of field samples collected in proximity to mine wastes in northeastern Arizona confirm the presence of As and U in soils and surrounding waters, as reported in a previous study from our research group. In this study, we measured As (<0.500 to 7.77 μg/L) and U (0.950 to 165 μg/L) in waters, as well as mine wastes (<20.0 to 40.0 mg/kg As and <60.0 to 110 mg/kg U) and background solids (<20.0 mg/kg As and <60.0 mg/kg U). Analysis with X-ray fluorescence (XRF) and electron microprobe show the co-occurrence of As and U with iron (Fe) and vanadium (V). These field conditions served as a foundation for additional laboratory experiments to assess the reactivity of metals in these mine wastes. Results from laboratory experiments indicate that labile and exchangeable As(V) was released to solution when solids were sequentially reacted with water and magnesium chloride (MgCl 2 ), while limited U was released to solution with the same reactants. The predominance of As(V) in mine waste solids was confirmed by X-ray absorption near edge (XANES) analysis. Both As and U were released to solution after reaction of solids in batch experiments with HCO 3 − . Both X-ray photoelectron spectroscopy (XPS) and XANES analysis determined the predominance of Fe(III) in the solids. Mössbauer spectroscopy detected the presence of nano-crystalline goethite, Fe(II) and Fe(III) in (phyllo)silicates, and an unidentified mineral with parameters consistent with arsenopyrite or jarosite in the mine waste solids. Our results suggest that As and U can be released under environmentally relevant conditions in mine waste, which is applicable to risk and exposure assessment.

Arizona↗
USGS2020

The GFDL Earth System Model Version 4.1 (GFDL-ESM 4.1): Overall coupled model description and simulation characteristics

We describe the baseline coupled model configuration and simulation characteristics of GFDL's Earth System Model Version 4.1 (ESM4.1), which builds on component and coupled model developments at GFDL over 2013–2018 for coupled carbon-chemistry-climate simulation contributing to the sixth phase of the Coupled Model Intercomparison Project. In contrast with GFDL's CM4.0 development effort that focuses on ocean resolution for physical climate, ESM4.1 focuses on comprehensiveness of Earth system interactions. ESM4.1 features doubled horizontal resolution of both atmosphere (2° to 1°) and ocean (1° to 0.5°) relative to GFDL's previous-generation coupled ESM2-carbon and CM3-chemistry models. ESM4.1 brings together key representational advances in CM4.0 dynamics and physics along with those in aerosols and their precursor emissions, land ecosystem vegetation and canopy competition, and multiday fire; ocean ecological and biogeochemical interactions, comprehensive land-atmosphere-ocean cycling of CO 2 , dust and iron, and interactive ocean-atmosphere nitrogen cycling are described in detail across this volume of JAMES and presented here in terms of the overall coupling and resulting fidelity. ESM4.1 provides much improved fidelity in CO 2 and chemistry over ESM2 and CM3, captures most of CM4.0's baseline simulations characteristics, and notably improves on CM4.0 in (1) Southern Ocean mode and intermediate water ventilation, (2) Southern Ocean aerosols, and (3) reduced spurious ocean heat uptake. ESM4.1 has reduced transient and equilibrium climate sensitivity compared to CM4.0. Fidelity concerns include (1) moderate degradation in sea surface temperature biases, (2) degradation in aerosols in some regions, and (3) strong centennial scale climate modulation by Southern Ocean convection.

Journal of Advances in Modeling Earth Systems (JAM↗
USGS1976

Physiological response to hooking stress in hatchery and wild rainbow trout (Salmo gairdneri)

This study evaluated the physiological response of rainbow trout to hooking stress after being played under standardized conditions (0&ndash;5 min) and estimated the time needed for recovery (to 72 h). Plasma osmolality and chloride measurements were used to evaluate osmoregulatory disturbances and gill ion-exchange function, and plasma glucose was used as an index of the generalized nonspecific physiological stress response. Hooking stress caused more severe blood chemistry differences in hatchery fish than in wild trout. Also, hooking stress imposed a greater stress on larger than on smaller hatchery rainbow trout. Higher water temperatures aggravated the delayed hyperglycemia and hyperchloremia in both hatchery and wild trout but only about 3 days were needed for recovery at 4, 10, or 20 C.

Transactions of the American Fisheries Society↗
USGS2019

Preliminary assessment of shallow groundwater chemistry near Goodell Creek, North Cascades National Park, Washington

Goodell Creek is located within North Cascades National Park and is high-quality habitat for Chinook salmon, which are listed as threatened under the Endangered Species Act. The creation of a levee near the mouth of the creek where it enters the Skagit River has cut off the historical flood plain from the active channel. There is an effort to remove the levee along the left bank of the creek to restore this connection and preserve this high-quality habitat; however, construction debris and blasting waste from the past have been used as fill during the creation of the levee in the 1980s, and there is concern that contaminated groundwater could reach the creek if the levee is breached. As a result, the U.S. Geological Survey, in cooperation with the National Park Service, assessed near-channel shallow-groundwater chemistry to determine how levee remediation should proceed. Groundwater was sampled in late summer in 2017. Deep groundwater at that time of year limited water-quality sampling. Six samples were collected in September 2017 and analyzed for nutrients, dissolved metals, and a suite of semi-volatile organic compounds. Laboratory data were almost always reported as below the method detection limits with the exception of data from a single shallow-groundwater well. Elevated concentrations of metals detected in water samples from this well were possibly caused by the buried metal in the vicinity of the sampling location. One sample collected close to the active channel of Goodell Creek showed no signs of contamination.

Washington↗
USGS2011

Characterization of stormwater runoff from bridges in North Carolina and the effects of bridge deck runoff on receiving streams

In 2008, the North Carolina General Assembly passed House Bill 2436 that required the North Carolina Department of Transportation (NCDOT) to study the water-quality effects of bridges on receiving streams. In response, the NCDOT and the U.S. Geological Survey (USGS) collaborated on a study to provide information necessary to address the requirements of the Bill. To better understand the effects of stormwater runoff from bridges on receiving streams, the following tasks were performed: (1) characterize stormwater runoff quality and quantity from a representative selection of bridges in North Carolina; (2) measure stream water quality upstream from selected bridges to compare bridge deck stormwater concentrations and loads to stream constituent concentrations and loads; and (3) determine if the chemistry of bed sediments upstream and downstream from selected bridges differs substantially based on presence or absence of a best management practice for bridge runoff.

North Carolina↗
USGS2011

Meteoric precipitation at Yucca Mountain, Nevada: Chemical and stable isotope analyses, 2006-09

Meteoric precipitation samples collected in 2006-09 at Yucca Mountain, Nevada, were analyzed for chemistry and stable isotope composition. Precipitation is the major source of infiltration to the unsaturated zone and of recharge to the saturated zone at Yucca Mountain. On February 28, 2005, seepage of water was observed about 40 to 80 meters below the ground surface within the Tiva Canyon Tuff in the South Ramp of the Exploratory Studies Facility tunnel within Yucca Mountain. This seepage was preceded by a 5-month period of above-average precipitation. Chemical and isotopic analysis of this seepage could not be used to estimate travel time, extent of water-rock interaction, and (or) evaporative water loss during percolation through the unsaturated zone due to the lack of corresponding chemical and isotopic analyses of precipitation inputs to the infiltration events that produced the seepage. In February 2006, collection of precipitation samples for chemical (major ions), delta oxygen-18 (&delta 18 O), and delta deuterium (&deltaD) analyses began at seven meteorological monitoring stations to provide baseline isotopic and chemical analyses. The sampling stations range in elevation from 1,131 to 1,562 meters. Each site has two collectors-one for chemical analysis and the other for isotopic analysis of precipitation. The collectors were sampled and emptied after each precipitation event. In 2006-09, 36 distinct precipitation events, with an average 3- to 4-day duration and an average 9.9 millimeters of accumulation, have been analyzed. The chemical composition of these samples of Yucca Mountain precipitation is relatively dilute but contains measurable and variable concentrations of Na + , Ca 2+ , NH + , NO 3 - , and SO 4 2- . Dust transported by typical winter storms and generated from soil carbonates is the main contributor to this precipitation chemistry. Elevated nitrate and ammonium concentrations may be linked to agriculture in the nearby Amargosa River valley to the south and west of Yucca Mountain. Cumulatively, &delta 18 O values range from 3.0 to -20.4 per mil (%o) and &deltaD values range from 10 to -14%o. Winter-season precipitation commonly has isotopically lighter compositions. The cumulative &delta18O plotted against &deltaD shows that precipitation samples define a line with slope of 6.4, less than the 8 of the Global Meteoric Water Line. This difference in slope, typical of arid environments, is chiefly the result of evaporation of falling raindrops due to warmer air temperatures. ;

Scientific Investigations Report↗