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Source-linked reports with geographic coverage including Nebraska.

At least 235 records · Page 13Linked to original sources
USGS2003

Differences in habitat use by blanding's turtles, Emydoidea blandingii, and painted turtles, Chysemys picta, in the Nebraska sandhills

We sampled a variety of wetlands in the Nebraska sandhills at Valentine National Wildlife Refuge. Significantly more individuals of painted turtles ( Chrysemys picta ) occurred in lakes and open waters than in marshes or small ponds, and the opposite was true for Blanding's turtles ( Emydoidea blandingii ). Besides this marked difference in habitat use, 46% of the captured E. blandingii in pond/marsh habitat were juveniles, but only 31.6% in lakes and open water. Current information suggests that marshes and small ponds are important habitat for juvenile turtles, especially Emydoidea blandingii .

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USGS2002

Use of environmental tracers and isotopes to evaluate sources of water, nitrate, and uranium in an irrigated alluvial valley, Nebraska

The effects of irrigation canals and the North Platte River on ground-water movement and quality in an irrigated alluvial valley, western Nebraska, were evaluated using environmental tracers. The results indicated that most of the ground water in the alluvium was derived from the North Platte River and generally was less than 30 years old. Ground-water-recharge rates varied substantially from about 0.6 to 9 feet per year with the larger recharge rates reflecting localized canal seepage. Younger water had higher nitrate concentrations than older water. Increases in nitrate concentrations in recharging ground water over time may be associated with an increase in nitrogen fertilizer use over time. Denitrification was limited in the ground water in the alluvium. Uranium concentrations in ground water resulted from dissolution of volcanic ash or other sediments in the underlying bedrock or incorporated in the alluvium. High uranium concentrations in the North Platte River during the winter months were a result of the addition of uranium-rich water from local tributaries and seepage of uranium-rich ground water.

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USGS2002

Flux of dissolved forms of mercury across the sediment-water interface in Lahontan Reservoir, Nevada

Field and laboratory studies were conducted between April 30, 2001 and July 19, 2001 to provide the first direct measurements of the benthic flux of dissolved (0.2-micrometer filtered) mercury species (total and methylated forms) between the bottom sediment and water column at three sites: two in the southern lobe and one in the northern lobe of Lahontan Reservoir, Nevada (Background, Fig. 1). Dissolved-mercury species and predominant ligands (represented by dissolved organic carbon, and sulfides) were the solutes of primary interest. Benthic flux, sometimes referred to as internal recycling, represents the transport of dissolved chemical species between the water column and the underlying sediment. Water-quality managers often assess and prioritize remediation strategies for aquatic systems, in particular Super Fund sites that have been adversely affected by anthropogenic activities. In the case of the Lahontan Reservoir along the Carson River, mercury associated with historic gold and silver extraction has been fluvially transported and accumulated in the bottom sediments. Frequent demands have been made by Super Fund site managers and the general public to quantify the connections between fluxes of contaminants and the health, abundance, and distribution of biological resources (Kuwabara and others, 1999). As part of a comprehensive examination of transport processes affecting mercury dynamics in Lahontan Reservoir, this study focuses on a poorly understood, yet potentially predominant, source of mercury to the reservoir water column, which is internal recycling, or benthic flux of mercury species and associated ligands. Mobilization, flux, and biological availability of mercury into the water column of the reservoir are affected by physical (e.g., advection and diffusion), chemical (i.e., oxidationreduction reactions, complexation and repartitioning) and biological processes (Flegal and others, 1991; Kuwabara and others, 1996; Grenz and others, 2000, Topping and others, 2001). The results described herein followed from the integration of current project studies with information needs identified by the U.S. Environmental Protection Agency, Region 9 (USEPA) to provide initial determinations of dissolved total and methyl-mercury fluxes from the sediments into the water column of Lahontan Reservoir. Recent mercury distribution and transformation studies in the Carson River system by Marvin-Dipasquale and others (2001) indicated the potential importance of sediment-water interactions in describing mercury speciation, its sources and sinks. Quantifying and understanding the magnitude and variability of these interactions are critical to the accurate assessment of contaminant sources and loads as well as to the development of process-integrated water-quality models for this mining-affected system. With a variety of strategies under consideration to determine how to most efficiently improve the water quality in the Carson River system, the primary question posed in this study was, “What processes regulate the fate and transport of mercury species in Lahontan Reservoir? In particular, are sources and sinks of dissolved total and methyl mercury associated with the bottom sediment within Lahontan Reservoir significant relative to major surface-water inputs from the Carson River?” The question was motivated by a number of factors. First, extraction of precious metals up gradient of the reservoir provide a historic source of elemental mercury that continues to be fluvially transported in dissolved and particulate phases (Hoffman and Taylor, 1998; Carroll and others, 2000; Carroll and Warwick, 2001). Elevated total and methyl mercury concentrations into the reservoir have been well documented (Priessler and others, 1999; Jones and others, 1999; Allander and others, 2001, Marvin-Dipasquale and others, 2001). Therefore, determining whether some fraction of this sediment-associated mercury can remobilize for transport to the overlying water and subsequently to down-stream portions of the Carson River is necessary. Second, elevated concentrations of mercury species in reservoir water, sediment, and fish have prompted a compilation, and comparison of dominant contaminant sources so that appropriate remedial strategies can be designed and implemented. Third, changes in oxidizing or reducing (redox) conditions and nutrient availability near the sediment-water interface (e.g., during phytoplankton blooms) can dramatically alter the mobility of metals and ligands associated with the bottom sediment as episodic sources of carbon settle out and accumulate (Thompson and others, 1981). Finally, there is a growing body of evidence from other aquatic systems that benthic flux or internal recycling of contaminants and nutrients is an important process to consider in developing appropriate ecosystem water-quality models (Wood and others, 1995; Kuwabara and others, 2000). The need for more refined numerical and conceptual models for mercury dynamics within the Carson River system thus clearly exists. This report is formatted unconventionally in a pyramid-like structure to effectively serve the needs of diverse parties interested in reviewing or acquiring information at various levels of detail (Appendix 1). The report enables quick transitions between the initial summary information (figuratively at the top of the pyramid) and later details of methods or results (that is, figuratively towards the base) using hyperlinks to supporting figures and tables, and an electronically linked Table of Contents.

Nebraska↗
USGS2002

Selection of nesting habitat by sharp-tailed grouse in the Nebraska sandhills

We evaluated nesting habitat selection (disproportionate use compared to availability) by plains sharp-tailed grouse ( Tympanuchus phasianellus jamesi ) on rangelands grazed by cattle ( Bos taurus ) relative to height, density, and heterogeneity of residual herbaceous vegetation remaining from previous growing seasons. Residual cover is critical for nesting sharp-tailed grouse and can be lacking on grazed rangelands. Aerial photography and a geographic information system were used to analyze residual cover height classes and several measures of residual cover heterogeneity in nest (n = 38) and random (n = 38) plots. Height classes corresponded to visual obstruction readings (VORs), the height to which total visual obstruction by vegetation occurs. Analyses were conducted for five spatial scales ranging from 1 to 16 ha to test for scale effects on nesting habitat selection. Sharp-tailed grouse selected nesting habitat with more area in tall (greater than or equal to 4 cm VOR) residual cover than at random sites at all scales, less area in short residual cover (less than 2 cm VOR) at the I-ha scale, and less area in short and medium (2 to 3.9 cm YOR) residual cover at the 2- through 16-ha scales. Selection of shrub habitat containing patches of shrubs was evident only at the 16-ha scale. Patches of tall residual cover were larger in nest plots than in random plots at the 8- and 16-ha scales, and patches of short cover were smaller in nest plots at the I-ha scale. Two scales of pattern defined by mean patch size were detected for overall residual cover, but did not relate to nesting habitat selection.

Nebraska↗
USGS2001

Toxicity and bioavailability of metals in the Missouri River adjacent to a lead refinery

This study is an evaluation of the potential environmental impacts of contaminated groundwater from the ASARCO metals refining facility adjacent to the Missouri River in Omaha, Nebraska. Surface waters, sediments, and sediment pore waters were collected from the Burt-Izard drain, which transects the facility, and from the Missouri River adjacent to the facility. Groundwater was also collected from the facility. Waters and sediments were analyzed for inorganic contaminants, and the toxicity of the waters was evaluated with the Ceriodaphnia dubia 7-day test. Concentrations of several elemental contaminants were highly elevated in the groundwater, but not in river sediment pore waters. Lead concentrations were moderately elevated in whole sediment at one site, but lead concentrations in pore waters were low due to apparent sequestration by acid-volatile sulfides. The groundwater sample was highly toxic to C. dubia , causing 100% mortality. Even at the lowest groundwater concentration tested (6.25%) C. dubia survival was reduced; however, at that concentration, reproduction was not significantly different from upstream porewater reference samples. Sediment pore waters were not toxic, except reproduction in pore water collected from one downstream site was somewhat reduced. The decrease in reproduction could not be attributed to measured elemental contaminants.

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USGS2001

Selected field and analytical methods and analytical results in the Dutch Flats area, western Nebraska, 1995-99

A study of the water resources of the Dutch Flats area in the western part of the North Platte Natural Resources District, western Nebraska, was conducted from 1995 through 1999 to describe the surface water and hydrogeology, the spatial distribution of selected water-quality constituents in surface and ground water, and the surface-water/ground-water interaction in selected areas. This report describes the selected field and analytical methods used in the study and selected analytical results from the study not previously published. Specifically, dissolved gases, age-dating data, and other isotopes collected as part of an intensive sampling effort in August and November 1998 and all uranium and uranium isotope data collected through the course of this study are included in the report.

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USGS2001

Hydrogeology and water quality of five principal aquifers in the Lower Platte South Natural Resources District, eastern Nebraska, 1994

The U.S. Geological Survey, in cooperation with the Lower Platte South Natural Resources District, conducted a hydrogeologic and water-quality reconnaissance study of the five principal aquifers in deposits of Quaternary age in the Natural Resources District. The purpose of the study was to delineate the approximate extent of the aquifers, to estimate volumes of drainable water in three aquifers, to provide information that could be useful in designing future ground-water-quality monitoring, and to determine baseline water-quality conditions in the aquifers, focusing on nitrate concentrations. The approximate lateral boundaries of the Dwight-Valparaiso, Crete-Princeton-Adams, and Waverly aquifers were defined as areas in which the thickness of continuous sand and gravel deposits was less than 40 feet. The three aquifers were determined to contain about 1,340,000; 1,540,000; and 172,000 acre-feet of drainable water, respectively, assuming a specific yield of 0.20. During the summer of 1994, ground-water samples were collected from 46 wells in the five aquifers and analyzed for nitrate and screened for triazine herbicides. Additionally, water samples from 39 of these wells were analyzed for major ions, iron, and manganese, and 35 were analyzed for radon. Water-quality analyses revealed that the water in the five aquifers had specific conductances that ranged from 399 to 2,040 micro-siemens per centimeter and was a calcium-carbonate to calcium-magnesium-sodium carbonate type. The most mineralized water samples were from the Crete-Princeton-Adams aquifer, which contained a median concentration of dissolved solids of 520 milligrams per liter. Concentrations of nitrate in water samples from the aquifers ranged from less than 0.05 to 23 milligrams per liter as nitrogen, and only six water samples exceeded the Maximum Contaminant Level established by the U.S. Environmental Protection Agency of 10 milligrams per liter. The median concentration of radon for water samples from the five aquifers was 300 picocuries per liter, which is the proposed Maximum Contaminant Level. Water samples from the Crete-Princeton-Adams and Waverly aquifers had the largest concentrations of radon among the five aquifers. The Crete-Princeton-Adams aquifer had a median concentration of 440 picocuries per liter, and the Waverly aquifer had a median concentration of 390 picocuries per liter. Herbicides were detected in water from only six wells, which were in four of the five aquifers. Atrazine, metabolites of atrazine, metolachlor, and metribuzin were detected in concentrations generally less than 1.00 microgram per liter.

Nebraska↗
USGS2001

Vertical profiles of streambed hydraulic conductivity determined using slug tests in central and western Nebraska

Many issues of water-resources management rely on modeling of ground-water/surfacewater interactions, and streambed hydraulic conductivity is a key parameter controlling the water fluxes across the stream/aquifer interface. However, in central and western Nebraska, this parameter is generally undefined. The U.S. Geological Survey, in cooperation with the Nebraska Platte River Cooperative Hydrology Study Group, performed slug tests at 15 stream sites in the Platte, Republican, and Little Blue River watersheds to determine the hydraulic conductivity of streambeds in central and western Nebraska. Slug tests were completed at several discrete depth intervals using pneumatic or mechanical methods, and the water-level response was monitored on site using a pressure transducer and laptop computer. Responses were analyzed using either the Bouwer and Rice or Springer and Gelhar methods. Vertical profiles of hydraulic conductivity with depth were developed and were compared to available information on lithology. The profiles and corresponding lithology showed that different types of streambeds were tested and suggested that some streambeds display a large variability in hydraulic conductivity with depth. In some cases, hydraulic conductivity values associated with nonstreambed materials could be identified from nearby lithologic descriptions. Seven of 15 sites had streambed values that ranged over more than 3 orders of magnitude, and that variability increased significantly when the measurements considered to be from nonstreambed materials were included. Streambed profiles from the Platte and South Platte River sites generally were more homogeneous and of larger hydraulic conductivity than the other sites. No restrictive layers were detected at any of the streambed sites on the main stems or the flood plains of the main stems of their respective watersheds. Alternatively, the profiles characterized by a restrictive streambed layer at some depth below the streambed surface were all from tributary sites out of the main-stem flood plain. These profiles can be used to represent the streambed hydraulic conductivity in central and western Nebraska in various applications, including modeling ground-water/surfacewater interactions.

Nebraska↗
USGS2000

Integration of a numerical model and remotely sensed data to study urban/rural land surface climate processes

Simulation of urban/rural land surface climate processes using boundary layer climate models requires accurate input data with regard to surface thermal and radiative properties. The research reported here resulted in development of a procedure to integrate the satellite-derived surface biophysical parameters with a boundary layer climate model for simulating spatial surface energy exchange. The procedure was tested through spatial surface energy balance simulation of an urban/rural landscape in eastern Nebraska. The modeled surface temperature and net radiation were compared to those derived from the concurrent satellite data. The errors of the modeled surface temperature were small, and were mainly attributed to uncertainties in the estimation of surface moisture availability and satellite-derived surface radiant temperature. Modeled net radiation was also in agreement with the values calculated from satellite data. Modeled turbulent heat fluxes were in general agreement as compared to those reported in the literature, but the model tended to overestimate the latent heat flux for most rural land cover types. It was concluded that by incorporation of satellite-derived surface physical parameters into a boundary layer model, simulation of spatial land surface climate processes was much improved. The method and procedures developed from this study can be utilized in other boundary layer climate models.

Nebraska↗
USGS2000

Identifying populations potentially exposed to agricultural pesticides using remote sensing and a Geographic Information System

Pesticides used in agriculture may cause adverse health effects among the population living near agricultural areas. However, identifying the populations most likely to be exposed is difficult. We conducted a feasibility study to determine whether satellite imagery could be used to reconstruct historical crop patterns. We used historical Farm Service Agency records as a source of ground reference data to classify a late summer 1984 satellite image into crop species in a three-county area in south central Nebraska. Residences from a population-based epidemiologic study of non-Hodgkin lymphoma were located on the crop maps using a geographic information system (GIS). Corn, soybeans, sorghum, and alfalfa were the major crops grown in the study area. Eighty-five percent of residences could be located, and of these 22% had one of the four major crops within 500 m of the residence, an intermediate distance for the range of drift effects from pesticides applied in agriculture. We determined the proximity of residences to specific crop species and calculated crop-specific probabilities of pesticide use based on available data. This feasibility study demonstrated that remote sensing data and historical records on crop location can be used to create historical crop maps. The crop pesticides that were likely to have been applied can be estimated when information about crop-specific pesticide use is available. Using a GIS, zones of potential exposure to agricultural pesticides and proximity measures can be determined for residences in a study.

Nebraska↗
USGS2000

Areas of gain and loss along the Platte River, central Nebraska, spring 1999

In an effort to protect endangered and other wildlife species, the governors of Nebraska, Colorado, and Wyoming, and the Secretary of the U.S. Department of the Interior signed an agreement in 1997 (Platte River Endangered Species Partnership, 1997) to initiate the development of a basin-wide habitat recovery program for the central reaches of the Platte River in Nebraska. This agreement recognizes the need to maintain minimal flows in the central reaches of the Platte River. An understanding of the surface-water and ground-water interaction along the central reaches of the Platte River is critical to deliver water to the targeted habitat areas. Therefore, a study by the U.S. Geological Survey (USGS), in cooperation with the Bureau of Reclamation and the U.S. Fish and Wildlife Service, was conducted to determine qualitatively the areas of gain and loss along the central Platte River between Gothenburg and Silver Creek, Nebraska (fig. 1). The purpose of this report is to present the results of the study.

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