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The Microscopic Imager (MI) on the Mars Exploration Rover Opportunity has returned images of Mars with higher resolution than any previous camera system, allowing detailed petrographic and sedimentological studies of the rocks and soils at the Meridiani Planum landing site. Designed to simulate a geologist's hand lens, the MI is mounted on Opportunity's instrument arm and can resolve objects 0.1 mm across or larger. This paper provides an overview of MI operations, data calibration, and analysis of MI data returned during the first 900 sols (Mars days) of the Opportunity landed mission. Analyses of Opportunity MI data have helped to resolve major questions about the origin of observed textures and features. These...
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This map shows the distribution of anomalous tungsten in the two sample fractions, magnetic (M-1) and nonmagnetic (NM-1) gold in the nonmagnetic (NM-1) fraction; these are plotted on a base which includes sample localities, topography, and generalized geology modified from Hedlund (1975a, b). It is part of a series of maps for several metals that accompany this folio. Distributions of the tungsten and gold values are shown on the accompanying histograms.
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A pore network model with cubic chambers and rectangular tubes was used to estimate the nonaqueous phase liquid (NAPL) dissolution rate coefficient, Kdissai, and NAPL/water total specific interfacial area, ai. Kdissai was computed as a function of modified Peclet number(Pe′) for various NAPL saturations (SN) and ai during drainage and imbibition and during dissolution without displacement. The largest contributor to ai was the interfacial area in the water-filled corners of chambers and tubes containing NAPL. When Kdissai was divided by ai, the resulting curves of dissolution coefficient, Kdiss versus Pe′ suggested that an approximate value of Kdiss could be obtained as a weak function of hysteresis or SN. Spatially...
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Unlike conventional flood control systems that frequently isolate rivers from ecologically-essential floodplain habitat, California's Yolo Bypass has been engineered to allow Sacramento Valley floodwaters to inundate a broad floodplain. From a flood control standpoint, the 24,000 ha leveed floodplain has been exceptionally successful based on its ability to convey up to 80% of the flow of the Sacramento River basin during high water events. Agricultural lands and seasonal and permanent wetlands within the bypass provide key habitat for waterfowl migrating through the Pacific Flyway. Our field studies demonstrate that the bypass seasonally supports 42 fish species, 15 of which are native. The floodplain appears to...
Categories: Publication; Types: Citation; Tags: Fisheries
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Hydrologists often attempt to estimate formation properties from aquifer tests for which only the hydraulic responses in a pumped well are available. Borehole storage, turbulent head losses, and borehole skin, however, can mask the hydraulic behavior of the formation inferred from the water level in the pumped well. Also, in highly permeable formations or in formations at significant depth below land surface, where there is a long column of water in the well casing, oscillatory water levels may arise during the onset of pumping to further mask formation responses in the pumped well. Usually borehole phenomena are confined to the early stages of pumping or recovery, and late-time hydraulic data can be used to estimate...
Categories: Publication; Types: Citation; Tags: Journal of Hydrology
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More than 70 individual VOCs were identified in the leachate plume of a closed municipal landfill. Concentrations were low when compared with data published for other landfills, and total VOCs accounted for less than 0.1% of the total dissolved organic carbon. The VOC concentrations in the core of the anoxic leachate plume are variable, but in all cases they were found to be near or below detection limits within 200 m of the landfall. In contrast to the VOCs, the distributions of chloride ion, a conservative tracer, and nonvolatile dissolved organic carbon, indicate little dilution over the same distance. Thus, natural attentuation processes are effectively limiting migration of the VOC plume. The distribution of...
Categories: Publication; Types: Citation; Tags: Groundwater
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The crystallization of calcium carbonate minerals plays an integral role in the water chemistry of terrestrial ecosystems. Humic substances, which are ubiquitous in natural waters, have been shown to reduce or inhibit calcite crystal growth in experiments. The purpose of this study is to quantify and understand the kinetic effects of hydrophobic organic acids isolated from the Florida Everglades and a fulvic acid from Lake Fryxell, Antarctica, on the crystal growth of calcite (CaCO3). Highly reproducible calcite growth experiments were performed in a sealed reactor at constant pH, temperature, supersaturation (Ω = 4.5), PCO2(10−3.5atm), and ionic strength (0.1 M) with various concentrations of organic acids. Higher...
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Investigation of water resources by the United States Geological Survey has consisted in large part of measurements of the volume of flow of streams and studies of the conditions affecting that flow, but it has comprised also investigation of such closely allied subjects as irrigation, water storage, water powers, underground waters, and quality of waters. Most of the results of these investigations have been published in the series of water-supply papers, but some have appeared in the monographs, bulletins, professional papers, and annual reports.
Categories: Publication; Types: Citation; Tags: Water Supply Paper
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The Sierra Nevada region is critical to the environment and economy of California. Its places and peoples provideessential natural resources including fresh water, clean power, working lands, and famous wilderness. The regionencompasses tremendous geographical, climatological, and ecological diversity that spans majestic mountains todeep desert basins. The climate consists of cool, wet winters and warm, dry summers with large differences due tolatitude (e.g., the southern Sierra is snowier than northern Sierra) and topography (e.g., the Westside is wetter thanthe Eastside). Variability is another notable feature of the climate with the region experiencing some of the largestyear-to-year climatic fluctuations in...
Categories: Publication; Types: Citation
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We investigate the spectral reflectance properties of channels and mountain ranges on Titan using data from Cassini's Visual and Infrared Mapping Spectrometer (VIMS) obtained during the T9 encounter (26 December 2005). We identify the location of channels and mountains using synthetic aperture radar maps obtained from Cassini's RADAR instrument during the T13 (30 April 2006) flyby. Channels are evident even in VIMS imaging with spatial resolution coarser than the channel size. The channels share spectral characteristics with Titan's dark blue terrain (e.g., the Huygens landing site) that is consistent with an enhancement in water ice content relative to the rest of Titan. We use this fact to measure widths of ???1...
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Extensive research has been conducted regarding the occurrence of herbicides in the hydrologic system, their fate, and their effects on human health and the environment. Few studies, however, have considered herbicide transformation products (degradates). In this study of Iowa ground water, herbicide degradates were frequently detected. In fact, herbicide degradates were eight of the 10 most frequently detected compounds. Furthermore, a majority of a herbicide's measured concentration was in the form of its degradates — ranging from 55 to over 99%. The herbicide detection frequencies and concentrations varied significantly among the major aquifer types sampled. These differences, however, were much more pronounced...
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During the summer of 1997, water samples were collected and analyzed for pesticides from 32 playa lakes of the High Plains that receive drainage from both cotton and corn agriculture in West Texas. The major cotton herbicides detected in the water samples were diuron, fluometuron, metolachlor, norflurazon, and prometryn. Atrazine and propazine, corn and sorghum herbicides, were also routinely detected in samples from the playa lakes. Furthermore, the metabolites of all the herbicides studied were found in the playa lake samples. In some cases, the concentration of metabolites was equal to or exceeded the concentration of the parent compound. The types of metabolites detected suggested that the parent compounds had...
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Water samples were collected from Midwestern streams in 1994–1995 and 1998 as part of a study to help determine if changes in herbicide use resulted in changes in herbicide concentrations since a previous reconnaissance study in 1989–1990. Sites were sampled during the first significant runoff period after the application of pre-emergent herbicides in 1989–1990, 1994–1995, and 1998. Samples were analyzed for selected herbicides, two atrazine metabolites, three cyanazine metabolites, and one alachlor metabolite. In the Midwestern USA, alachlor use was much greater in 1989 than in 1995, whereas acetochlor was not used in 1989 but was commonly used in 1995. The use of atrazine, cyanazine, and metolachlor was approximately...
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The Cuyuna iron-ore district is in central Minnesota in Morrison, Crow Wing, and Aitkin Counties. The length of the district is about 68 miles, extending from near Randall in Morrison County ot a point 11 miles east of the community of Hassmann in Aitkin County, and the maximum know width is about 25 miles near the center of the district. Current mining activity is confined to a much smaller area about 10 miles longs and 3 miles wide near Crosby and Ironton in Crow Wing County. This investigation has been restricted to the active area plus a marginal strip in which much exploratory drilling has been done. The average annual production of iron ore and manganiferous iron ore from the district during 1940-50 was...
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As restoration of tidal freshwater wetlands has progressed in North America and Eurasia, research findings have continued to emerge on the postrestoration success of these ecosystems. The most common approaches used to restore tidal freshwater wetlands involve excavation or placement of dredged sediment to restore tidal hydrology compatible with vegetation establishment and managed realignment or diversion, which involves reconnecting former wetlands to tides by breaching dikes or levees. Postconstruction monitoring of tidal freshwater wetland restoration projects commonly includes not only studies of hydrology, soil, and vegetation but also geomorphology, microbial communities, seed banks, fish, birds, and invertebrates....
Categories: Publication; Types: Citation
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Cassini radar images show a variety of fluvial channels on Titan's surface, often several hundreds of kilometers in length. Some (predominantly at low- and mid-latitude) are radar-bright and braided, resembling desert washes where fines have been removed by energetic surface liquid flow, presumably from methane rainstorms. Others (predominantly at high latitudes) are radar-dark and meandering and drain into or connect polar lakes, suggesting slower-moving flow depositing fine-grained sediments. A third type, seen predominantly at mid- and high latitudes, have radar brightness patterns indicating topographic incision, with valley widths of up to 3 km across and depth of several hundred meters. These observations...
Categories: Publication; Types: Citation; Tags: Planetary and Space Science