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At least 1,747 records · Page 97Linked to original sources
USGS1988

Comparison of methods to determine selenium species in saturation extracts of soils from the western San Joaquin Valley, California

Methods to determine soluble concentrations of selenite, selenate, and organic selenium were compared on saturation extracts of soil samples collected from three sites on the Panache Creek alluvial fan in the western San Joaquin Valley, California. The methods were used in combination with hydridegeneration atomic-absorption spectrometry for detection of selenium and included a selective chemical digestion method and three chromatography methods using XAD-8 resin, Sep-Pac C 18 cartridge, and a combination of XAD-8 resin and activated charcoal. Undigested organic matter in some of the extracts inhibited selenium detection when using the digestion and Sep-Pac C18 methods, but the interference was removed by using the XAD-8 method. Combining XAD-8 resin and activated charcoal was an unacceptable method, because the activated charcoal removed selenite and selenate. Ninety-eight percent of the selenium in the extracts was selenate and about 100 percent of the isolated organic selenium was associated with the humic acid fraction of dissolved-organic matter.

California↗
USGS1993

Water-quantity, water-quality, soil, and sediment data collected at Goose Egg Spring, Natrona County, Wyoming, May and July 1992

Recent, apparent increases in sediment accumulation in Goose Egg Spring, southwest of Casper, Wyoming, may have been the result of natural environmental processes or quarry operations near the spring in late 1991. Goose Egg Spring is the sole source of water for the Dan Speas Fish Rearing Station. This facility is operated by the Wyoming Game and Fish Commission and produces about 77,000 kilograms of stockable fish annually. Samples of the spring water, surrounding soils, and bottom sediment were collected. Methods used in obtaining all samples are discussed. Results of chemical analyses of the spring water, stratigraphic description of core samples, particle-size distribution analysis, visual mineralogical assessment, and X-ray diffraction analysis were used to characterize Goose Egg Spring and the immediately surrounding area in May and July 1992.

Open-File Report↗
USGS1995

Using chloride and chlorine-36 as soil-water tracers to estimate deep percolation at selected locations on the U.S. Department of Energy Hanford site, Washington

Long-term average deep-percolation rates of water from precipitation on the U.S. Department of Energy Hanford Site in semiarid south-central Washington, as estimated by a chloride mass-balance method, range from 0.008 to 0.30 mm/yr (millimeters per year) at nine locations covered by a variety of fine-grain soils and vegetated with sagebrush and other deep-rooted plants plus sparse shallow-rooted grasses. Deep-percolation rates estimated using a chlorine-36 bomb-pulse method at three of the nine locations range from 2.1 to 3.4 mm/yr. Because the mass-balance method may underestimate percolation rates and the bomb-pulse method probably overestimates percolation rates, estimates by the two methods probably bracket actual rates. These estimates, as well as estimates by previous investigators who used different methods, are a small fraction of mean annual precipitation, which ranges from about 160 to 210 mm/yr at the different test locations. Estimates by the mass-balance method at four locations in an area that is vegetated only with sparse shallow-rooted grasses range from 0.39 to 2.0 mm/yr. Chlorine-36 data at one location in this area were sufficient only to determine that the upper limit of deep percolation is more than 5.1 mm/yr. Although estimates for locations in this area are larger than the estimates for locations with deep-rooted plants, they are at the lower end of the range of estimates for this area made by previous investigators.

Washington↗
USGS1997

Fire-induced water-repellent soils, an annotated bibliography

The development and nature of water-repellent, or hydrophobic, soils are important issues in evaluating hillslope response to fire. The following annotated bibliography was compiled to consolidate existing published research on the topic. Emphasis was placed on the types, causes, effects and measurement techniques of water repellency, particularly with respect to wildfires and prescribed burns. Each annotation includes a general summary of the respective publication, as well as highlights of interest to this focus. Although some references on the development of water repellency without fires, the chemistry of hydrophobic substances, and remediation of water-repellent conditions are included, coverage of these topics is not intended to be comprehensive. To develop this database, the GeoRef, Agricola, and Water Resources Abstracts databases were searched for appropriate references, and the bibliographies of each reference were then reviewed for additional entries. Additional references will be added to this bibliography as they become available. The annotated bibliography can be accessed on the Web at http://geohazards.cr.usgs.gov/html_files/landslides/ofr97-720/biblio.html. A database consisting of the references and keywords is available through a link at the above address. This database was compiled using EndNote2 plus software by Niles and Associates, and is necessary to search the database.

Open-File Report↗
USGS1988

Element concentrations in soils and other surficial materials of Alaska

Mean concentrations of 35 elements, ash yields, and pH have been estimated for samples of sils and other unconsolidated surficial materials from 266 collection locations throughout Alaska. These background values can be applied to studies of environmental geochemistry and health, wildlife management, and soil-forming processes in cold climates and to computation of element abundances on a regional or worldwide scale. Limited data for an additoinal eight elements are also presented. Materials were collected using a one-way, three-level, analysis-of-variance samplling design in which collecting procedures were simplified for the convenience of the many volunteer field workers. The sample collectors were asked to avoid locations of known mineral deposits and obvious contamination, to take samples at a depth of about 20 cm where possible, and to take a replicate sample about 100 m distant from the first sample collected. With more than 60 percent of the samples replicated and 14 percent of the samples split for duplicate laboratory analyses, reliable estimates were made of the variability in element concentrations at two geographic scales and of the error associated with sample handling and laboratory procedures. Mean concentrations of most elements in surficial materials from the state of alaska correspond well with those reported in similar materials from the conterminous United STatess. Most element concentrations and ranges in samples of stream and lake sediments from Alaska, however, as reported in the literature, do not correspond well with those found in surficial materials of this study. This lack of correspondence is attributed to (1) a merger of two kinds ofsediments (stream and lake) for calculating means; (2) elimination from the sediment mean calculations of values below the limit of quantitative determination; (3) analytical methods different from those of the surficial materials study; and (4) most importantly, the inherent differences in chemistry of the materials. The distribution of variability in element concentrations o Alaskan surficial-material samples was, for most elements, largely among sampling locations, with only a samll part of the variability occurring between replicate samples at a location. The geochemical uniformity within sampling locations in Alaska is an expression of uniform geochemical cycling processes within small geographic areas. The concentration values for 35 elements in 266 samples were plotted on maps by symbols representing classes of concentration frequency distributions. These plotted symbols form patterns that may or may not be possible to interpret but nevertheless show differences that are observable at several geographical scales. The largest pattern is one generally low concentrations of many elements in materials from arctic and oceanic tundra regions, as contrasted to their often high concentrations in samples from interior and southeastern Alaska. The patttern for sodium isespecially pronounced. Intermediate-sized patterns are shown, for example, by the generally high values for magnesium and low values for silicon in the coastal forest region of southeastern Alaska. Many elements occur at low concentratoins in samples from the Alaskan peninsula and the Aleutian Islands. The degree of confidence in patterns of element abundance is expected to be in direct proportion to the number of samples included in the area. As the patterns become smaller, the probability increases that the patterns are not reproducible.

Alaska↗
USGS2006

Methane gas concentration in soils and ground water, Carbon and Emery Counties, Utah, 1995-2003

The release of methane gas from coal beds creates the potential for it to move into near-surface environments through natural and human-made pathways. To help ensure the safety of communities and determine the potential effects of development of coal-bed resources, methane gas concentrations in soils and ground water in Carbon and Emery Counties, Utah, were monitored from 1995 to 2003. A total of 420 samples were collected, which contained an average methane concentration of 2,740 parts per million by volume (ppmv) and a median concentration of less than 10 ppmv. On the basis of spatial and temporal methane concentration data collected during the monitoring period, there does not appear to be an obvious, widespread, or consistent migration of methane gas to the near-surface environment.

Utah↗
USGS2009

Using the Soil and Water Assessment Tool (SWAT) to Simulate Runoff in Mustang Creek Basin, California

This study is an evaluation of the calibration and validation of the Soil and Water Assessment Tool (SWAT) version 2005 watershed model for the Mustang Creek Basin, San Joaquin Valley, California. The study is part of a national study on the process of agricultural chemical movement through the hydrologic system, which is being done by the U.S. Geological Survey (USGS) National Water-Quality Assessment program. The SWAT model was used to simulate streamflow in the Mustang Creek Basin on the basis of a set of model inputs derived and modified from various data sources. The 2005 version of the model was calibrated for 29 days in February 2004, and validated for 58 days in January and February 2005. Measured streamflow for a USGS gaging station was used for model calibration and validation. Results of the simulated monthly streamflow had a Nash Sutcliffe efficiency value of 0.72 during the calibration period. The 2005 version of the model was unsuccessful in simulating streamflow during the validation period, as indicated by a Nash Sutcliffe efficiency value of 0.33. This lack of a successful simulation probably is due to the limited amount of measured streamflow data available for calibration, the ephemeral nature of flows in Mustang Creek, and the fact that the SWAT model was developed primarily for long time period (2 years and more) simulations and not for limited monthly simulations as used in Mustang Creek.

Scientific Investigations Report↗
USGS2017

Groundwater discharge by evapotranspiration, flow of water in unsaturated soil, and stable isotope water sourcing in areas of sparse vegetation, Amargosa Desert, Nye County, Nevada

This report documents methodology and results of a study to evaluate groundwater discharge by evapotranspiration (GWET) in sparsely vegetated areas of Amargosa Desert and improve understanding of hydrologic-continuum processes controlling groundwater discharge. Evapotranspiration and GWET rates were computed and characterized at three sites over 2 years using a combination of micrometeorological, unsaturated zone, and stable-isotope measurements. One site (Amargosa Flat Shallow [AFS]) was in a sparse and isolated area of saltgrass ( Distichlis spicata ) where the depth to groundwater was 3.8 meters (m). The second site (Amargosa Flat Deep [AFD]) was in a sparse cover of predominantly shadscale ( Atriplex confertifolia ) where the depth to groundwater was 5.3 m. The third site (Amargosa Desert Research Site [ADRS]), selected as a control site where GWET is assumed to be zero, was located in sparse vegetation dominated by creosote bush ( Larrea tridentata ) where the depth to groundwater was 110 m. Results indicated that capillary rise brought groundwater to within 0.9 m (at AFS) and 3 m (at AFD) of land surface, and that GWET rates were largely controlled by the slow but relatively persistent upward flow of water through the unsaturated zone in response to atmospheric-evaporative demands. Greater GWET at AFS (50 ± 20 millimeters per year [mm/yr]) than at AFD (16 ± 15 mm/yr) corresponded with its shallower depth to the capillary fringe and constantly higher soil-water content. The stable-isotope dataset for hydrogen (δ 2 H) and oxygen (δ 18 O) illustrated a broad range of plant-water-uptake scenarios. The AFS saltgrass and AFD shadscale responded to changing environmental conditions and their opportunistic water use included the time- and depth-variable uptake of unsaturated-zone water derived from a combination of groundwater and precipitation. These results can be used to estimate GWET in other areas of Amargosa Desert where hydrologic conditions are similar.

Nevada↗
USGS2023

Updated estimates of water budget components for the Mississippi Embayment Region using a soil-water-balance model, 2000–2020

A Soil-Water-Balance (SWB) model for the Mississippi embayment region in Arkansas, Tennessee, Mississippi, and Louisiana was constructed and calibrated to gain insight into potential recharge patterns for the Mississippi River Valley alluvial aquifer, which has had substantial drawdown under intense pumping stress over the last several decades. An analysis of the net infiltration term from the SWB model combined with newly gathered airborne electromagnetic geophysical data on the surficial sediments in a calibrated modular three-dimensional finite-difference (MODFLOW 6) groundwater flow model of one area in the alluvial plain found that the distribution of net infiltration was significantly different from the recharge that gets to the water table through the complicated silt and clay stratigraphy of the unsaturated zone. The net infiltration of water through the rooting zone as simulated by SWB ranges from 5.7 to 12.3 inches per year in the alluvial plain part of the model domain, and is fairly evenly distributed within local areas. Recharge to the underlying aquifer is less and is much more focused in particular zones where the connectivity through the upper layers of the unsaturated zone above the water table is greater, indicating possible horizontal flow and perched water table conditions in the unsaturated zone. Runoff and net infiltration together account for 32 percent of the incoming precipitation overall and somewhat higher percentages in the alluvial plain area on an annual basis. These terms are much higher in the fall and winter than in the summer. Actual evapotranspiration accounts for between 62 and 72 percent on average of the annual precipitation but dominates all other terms in the summer months. Without irrigation, summertime net infiltration and runoff would be near zero in the crop-dominated alluvial plain area. The SWB model reproduced reported irrigation rates for corn, soybeans, rice, and cotton on an annual basis fairly well. The SWB model for the Mississippi embayment region was calibrated using more than 15,000 observations representing four parts of the calculated water budget: actual evapotranspiration, surface runoff, net infiltration, and irrigation. Using a Monte Carlo approach to determine the uncertainty in the model results stemming from the uncertainty in the model parameters used in the calibration, the uncertainty in the annual actual evapotranspiration values was around 5 percent, whereas the uncertainty in the irrigation, net infiltration, and runoff was around 20 percent.

Mississippi Embayment Region↗
USGS2007

U.S. Geological Survey Field Leach Test for Assessing Water Reactivity and Leaching Potential of Mine Wastes, Soils, and Other Geologic and Environmental Materials

The U. S. Geological Survey (USGS) has developed a fast (5-minute), effective, simple, and cost-effective leach test that can be used to simulate the reactions that occur when materials are leached by water. The USGS Field Leach Test has been used to predict, assess, and characterize the geochemical interactions between water and a broad variety of geologic and environmental matrices. Examples of some of the samples leached include metal mine wastes, various types of dusts, biosolids (processed sewage sludge), flood and wetland sediments, volcanic ash, forest-fire burned soils, and many other diverse matrices. The Field Leach Test has been an integral part of these investigations and has demonstrated its value as a geochemical characterization tool. It has enabled investigators to identify which constituents are water reactive, soluble, mobilized, and made bioaccessible because of leaching by water, and to understand potential impacts of these interactions on the surrounding environment.

Techniques and Methods↗
USGS1993

Distribution of volatile organic compounds in soil vapor in the vicinity of a defense fuel supply point, Hanahan, South Carolina

Two passive soil-vapor sampling techniques were used in the vicinity of a defense fuel supply point in Hanahan, South Carolina, to identify areas of potential contamination of the shallow water table aquifer by volatile organic compounds (VOC's). Both techniques involved the burial of samplers in the vadose zone and the saturated bottom sediments of nearby streams. One method, the empty-tube technique, allowed vapors to pass through a permeable membrane and accumulate inside an inverted empty test tube. A sample was extracted and analyzed on site by using a portable gas chromatograph. As a comparison to this method, an activated-carbon technique, also was used in certain areas. This method uses a vapor collector consisting of a test tube containing activated carbon as a sorbent for VOC's.

Water-Resources Investigations Report↗
USGS2009

Improving the design of amphibian surveys using soil data: A case study in two wilderness areas

Amphibian populations are known, or thought to be, declining worldwide. Although protected natural areas may act as reservoirs of biological integrity and serve as benchmarks for comparison with unprotected areas, they are not immune from population declines and extinctions and should be monitored. Unfortunately, identifying survey sites and performing long-term fieldwork within such (often remote) areas involves a special set of problems. We used the USDA Natural Resource Conservation Service Soil Survey Geographic (SSURGO) Database to identify, a priori, potential habitat for aquatic-breeding amphibians on North and South Manitou Islands, Sleeping Bear Dunes National Lakeshore, Michigan, and compared the results to those obtained using National Wetland Inventory (NWI) data. The SSURGO approach identified more target sites for surveys than the NWI approach, and it identified more small and ephemeral wetlands. Field surveys used a combination of daytime call surveys, night-time call surveys, and perimeter surveys. We found that sites that would not have been identified with NWI data often contained amphibians and, in one case, contained wetland-breeding species that would not have been found using NWI data. Our technique allows for easy a priori identification of numerous survey sites that might not be identified using other sources of spatial information. We recognize, however, that the most effective site identification and survey techniques will likely use a combination of methods in addition to those described here.

Natural Areas Journal↗
USGS2014

Anthrax and the geochemistry of soils in the contiguous United States

Soil geochemical data from sample sites in counties that reported occurrences of anthrax in wildlife and livestock since 2000 were evaluated against counties within the same states (MN, MT, ND, NV, OR, SD and TX) that did not report occurrences. These data identified the elements, calcium (Ca), manganese (Mn), phosphorus (P) and strontium (Sr), as having statistically significant differences in concentrations between county type (anthrax occurrence versus no occurrence). Tentative threshold values of the lowest concentrations of each of these elements (Ca = 0.43 wt %, Mn = 142 mg/kg, P = 180 mg/kg and Sr = 51 mg/kg) and average concentrations (Ca = 1.3 wt %, Mn = 463 mg/kg, P = 580 mg/kg and Sr = 170 mg/kg) were identified from anthrax-positive counties as prospective investigative tools in determining whether an outbreak had “potential” or was “likely” at any given geographic location in the contiguous United States.

Alabama, California, Colorado, Minnesota, Montana,↗
USGS2018

Calibration of a field-scale Soil and Water Assessment Tool (SWAT) model with field placement of best management practices in Alger Creek, Michigan

Subwatersheds within the Great Lakes “Priority Watersheds” were targeted by the Great Lakes Restoration Initiative (GLRI) to determine the effectiveness of the various best management practices (BMPs) from the U.S. Department of Agriculture-Natural Resources Conservation Service National Conservation Planning (NCP) Database. A Soil and Water Assessment Tool (SWAT) model is created for Alger Creek, a 50 km 2 tributary watershed to the Saginaw River in Michigan. Monthly calibration yielded very good Nash–Sutcliffe efficiency (NSE) ratings for flow, sediment, total phosphorus (TP), dissolved reactive phosphorus (DRP), and total nitrogen (TN) (0.90, 0.79, 0.87, 0.88, and 0.77, respectively), and satisfactory NSE rating for nitrate (0.51). Two-year validation results in at least satisfactory NSE ratings for flow, sediment, TP, DRP, and TN (0.83, 0.54, 0.73, 0.53, and 0.60, respectively), and unsatisfactory NSE rating for nitrate (0.28). The model estimates the effect of BMPs at the field and watershed scales. At the field-scale, the most effective single practice at reducing sediment, TP, and DRP is no-tillage followed by cover crops (CC); CC are the most effective single practice at reducing nitrate. The most effective BMP combinations include filter strips, which can have a sizable effect on reducing sediment and phosphorus loads. At the watershed scale, model results indicate current NCP BMPs result in minimal sediment and nutrient reductions (<10%).

Michigan↗
USGS2011

Enhanced decomposition offsets enhanced productivity and soil carbon accumulation in coastal wetlands responding to climate change

Coastal wetlands are responsible for about half of all carbon burial in oceans, and their persistence as a valuable ecosystem depends largely on the ability to accumulate organic material at rates equivalent to relative sea level rise. Recent work suggests that elevated CO 2 and temperature warming will increase organic matter productivity and the ability of marshes to survive sea level rise. However, we find in a series of preliminary experiments that organic decomposition rates increase by about 20% per degree of warming. Our measured temperature sensitivity is similar to studies from terrestrial systems, three times as high as the response of salt marsh productivity to temperature warming, and greater than the productivity response associated with elevated CO 2 in C 3 marsh plants. Although the experiments were simple and of short duration, they suggest that enhanced CO 2 and warmer temperatures could actually make marshes less resilient to sea level rise, and tend to promote a release of soil carbon. Simple projections indicate that elevated temperatures will increase rates of sea level rise more than any acceleration in organic matter accumulation, suggesting the possibility of a positive feedback between climate, sea level rise, and carbon emissions in coastal environments.

Virginia↗
USGS2012

Sensitivity analysis of the GEMS soil organic carbon model to land cover land use classification uncertainties under different climate scenarios in Senegal

Spatially explicit land cover land use (LCLU) change information is needed to drive biogeochemical models that simulate soil organic carbon (SOC) dynamics. Such information is increasingly being mapped using remotely sensed satellite data with classification schemes and uncertainties constrained by the sensing system, classification algorithms and land cover schemes. In this study, automated LCLU classification of multi-temporal Landsat satellite data were used to assess the sensitivity of SOC modeled by the Global Ensemble Biogeochemical Modeling System (GEMS). The GEMS was run for an area of 1560 km 2 in Senegal under three climate change scenarios with LCLU maps generated using different Landsat classification approaches. This research provides a method to estimate the variability of SOC, specifically the SOC uncertainty due to satellite classification errors, which we show is dependent not only on the LCLU classification errors but also on where the LCLU classes occur relative to the other GEMS model inputs.

Biogeosciences↗
USGS2011

Enhanced decomposition offsets enhanced productivity and soil carbon accumulation in coastal wetlands responding to climate change

Coastal wetlands are responsible for about half of all carbon burial in oceans, and their persistence as a valuable ecosystem depends largely on the ability to accumulate organic material at rates equivalent to relative sea level rise. Recent work suggests that 5 elevated CO2 and temperature warming will increase organic matter productivity and the ability of marshes to survive sea level rise. However, we find that organic decomposition rates increase by about 12% per degree of warming. Our measured temperature sensitivity is similar to studies from terrestrial systems, twice as high as the response of salt marsh productivity to temperature warming, and roughly equivalent to the productivity response associated with elevated CO2 10 in C3 marsh plants. Therefore, enhanced CO2 and warmer temperatures may actually make marshes less resilient to sea level rise, and tend to promote a release of soil carbon. Simple projections indicate that elevated temperatures will increase rates of sea level rise more than any acceleration in organic matter accumulation, suggesting the possibility of a positive feedback between 15 climate, sea level rise, and carbon emissions in coastal environment

Biogeosciences Discussions↗
USGS2019

Climate, snow, and soil moisture data set for the Tuolumne and Merced river watersheds, California, USA

We present hourly climate data to force land surface process models and assessments over the Merced and Tuolumne watersheds in the Sierra Nevada, California, for the water year 2010–2014 period. Climate data (38 stations) include temperature and humidity (23), precipitation (13), solar radiation (8), and wind speed and direction (8), spanning an elevation range of 333 to 2987 m. Each data set contains raw data as obtained from the source (Level 0), data that are serially continuous with noise and nonphysical points removed (Level 1), and, where possible, data that are gap filled using linear interpolation or regression with a nearby station record (Level 2). All stations chosen for this data set were known or documented to be regularly maintained and components checked and calibrated during the period. Additional time-series data included are available snow water equivalent records from automated stations (8) and manual snow courses (22), as well as distributed snow depth and co-located soil moisture measurements (2–6) from four locations spanning the rain–snow transition zone in the center of the domain. Spatial data layers pertinent to snowpack modeling in this data set are basin polygons and 100 m resolution rasters of elevation, vegetation type, forest canopy cover, tree height, transmissivity, and extinction coefficient. All data are available from online data repositories ( https://doi.org/10.6071/M3FH3D ).

California↗