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This dataset includes the field measurements and laboratory analyses of surface water, seston, and sediment collected from Lake Powell, within Glen Canyon National Recreation area (GLCA), during high flow (May-June 2014) and low flow (August 2015) conditions. The study area includes 12-13 sampling sites that follow a transect spanning the entire length of the reservoir from the Colorado River inflow to the Glen Canyon dam, as well as the San Juan River arm, the Escalante River arm and West Canyon. Bed sediment samples were analyzed for mercury speciation, methylmercury production and degradation rates, total reduced sulfur, iron speciation, organic content, and 16S rRNA gene templates as a proxy for microbial abundances....
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This dataset contains stable isotope (δ13C) and radioisotope (Δ14C) compositions of dissolved inorganic carbon, dissolved organic carbon, particulate organic carbon, and bed material organic carbon samples collected from rivers in the Upper Mississippi River Basin between October 2014 and February 2016. Rivers were sampled at USGS gaging stations: Minnesota River at Fort Snelling State Park, MN (gage #05330920), Mississippi River at Hwy 610 in Brooklyn Park, MN (gage #05288500), St. Croix River at Prescott, WI (gage #05344490), Mississippi River at Prescott, WI (gage #05344500), and Chippewa River at Durand, WI (gage #05369500). One site was also sampled at a location that is not co-located with a gaging station:...
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The U.S. Geological Survey is studying Lake Koocanusa, a border reservoir between British Columbia in Canada and Montana, in collaboration with the Montana Department of Environmental Quality and the U.S. Environmental Protection Agency (Region 8). This work is part of a multi-agency project to apply an ecosystem-scale selenium modeling methodology (Presser and Luoma, 2010) to the lake to support development of a site-specific selenium guideline for the protection of aquatic life. This Data Release makes available measurements taken during the periods of May, 2015 to October, 2015 and April, 2016 to September, 2016. Spatially and temporally matched sets of dissolved and suspended particulate material selenium concentrations...
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Our research focuses on assessing the components of the Net Ecoystem Carbon Balance using the eddy covariance approach to measure atmospheric fluxes of heat, energy, carbon dioxide and methane and testing equipment and techniques to measure the tidal exchange of dissolved organic (DOC) and inorganic carbon (DIC). The atmospheric flux tower is located south of Solano Land Trust's Rush Ranch, a working ranch encompassing 2,070 acres of marsh and rolling grasslands that provides both recreational and educational experiences for the public (http://www.solanolandtrust.org/RushRanch.aspx). Lateral fluxes are being collected at the San Francisco Bay National Estuarine Research Reserve First Mallard water quality station...
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The Gulf of Alaska is one of the most productive marine ecosystems on Earth, supporting salmon fisheries that alone provide large economic benefits to Southeast Alaska. The region also has a vibrant and growing tourism industry. Glaciers are central to many of the area’s natural processes and economic activities, but the rates of glacier loss in Alaska are among the highest on Earth. Glacier loss threatens to significantly change the amount and timing of nutrients delivered by streams to near-shore habitats. Changes in glacier runoff into the ocean may also impact coastal currents that contribute to vibrant nearshore marine ecosystems. Improving our understanding of how ecosystems depend on glaciers and what glacier...
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Invasions of the annual species cheatgrass (Bromus tectorum) in North American ecosystems present a threat to the population viability of native plant and animal species. In the interest of curtailing B. tectorum success, we manipulated the biogeochemistry of Canyonlands National Park soils in greenhouse and germination experiments. We compared growth parameters of B. tectorum and a native perennial, Hilaria jamesii, in greenhouse experiments utilizing 10 soil additives. Biomass of B. tectorum growing in conjuction with H. jamesii was greater than that growing in monocultures, suggesting facilitation of Bromus growth by H. jamesii. The opposite trend was true for H. jamesii, indicating that Bromus inhibits H. jamesii...
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Atmospheric depostion and stream discharge and solutes were measured for three years (September 1984 - August 1987) in two mixed conifer watersheds in Sequoia National Park, in the southern Sierra Nevada of California. The Log Creek watershed (50 ha, 2067-2397 m elev.) is drained by a perennial stream, while Tharp's Creek watershed (13 ha, 2067-2255 m elev.) contains an intermittent stream. Dominant trees in the area include Abies concolor (white fir), Sequoiadendron giganteum (giant sequoia), A. magnifica (red fir), and Pinus lambertiana (sugar pine). Bedrock is predominantly granite and granodiorite, and the soils are mostly Pachic Xerumbrepts. Over the three year period, sulfate (SO42-), nitrate (NO3-), and chloride...
Categories: Publication; Types: Citation; Tags: Biogeochemistry
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In this study, we examined N gas loss as nitric oxide (NO) from N-fixing biologically crusted soils in Canyonlands National Park, Utah. We hypothesized that NO gas loss would increase with increasing N fixation potential of the biologically crusted soil. NO fluxes were measured from biologically crusted soils with three levels of N fixation potential (Scytonema-Nostoc-Collema spp. (dark)>Scytonema-Nostoc-Microcoleus spp. (medium)>Microcoleus spp. (light)) from soil cores and field chambers. In both cores and field chambers there was a significant effect of crust type on NO fluxes, but this was highly dependent on season. NO fluxes from field chambers increased with increasing N fixation potential of the biologically...
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Pollution of inland waters by agricultural land use is a concern in many areas of the world, and especially in arid regions, where water resources are inherently scarce. This study used physical and chemical water quality and stable nitrogen isotope (δ15N) measurements from zooplankton to examine nitrogen (N) sources and concentrations in four small lakes of Khorezm, Uzbekistan, an arid, highly agricultural region, which is part of the environmentally-impacted Aral Sea Basin. During the 2-year study period, ammonium concentrations were the highest dissolved inorganic N species in all lakes, with a maximum of 3.00 mg N l−1 and an average concentration of 0.62 mg N l−1. Nitrate levels were low, with a maximum concentration...
Categories: Publication; Types: Citation; Tags: Biogeochemistry
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Abstract Decomposition is central to understanding ecosystem carbon exchange and nutrient-release processes. Unlike mesic ecosystems, which have been extensively studied, xeric landscapes have received little attention; as a result, abiotic soil-respiration regulatory processes are poorly understood in xeric environments. To provide a more complete and quantitative understanding about how abiotic factors influence soil respiration in xeric ecosystems, we conducted soil- respiration and decomposition-cloth measurements in the cold desert of southeast Utah. Our study evaluated when and to what extent soil texture, moisture, temperature, organic carbon, and nitrogen influence soil respiration and examined whether...
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We investigated several forms of phosphorus (P) in dryland soils to examine the chemical and textural controls on P stabilization on a diverse set of substrates. We examined three P fractions including labile, moderately labile, and occluded as determined by a modified Hedley fractionation technique. The P fractions were compared to texture measurements and total elemental concentrations determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Labile P related to the absence of materials involved in P sorption. Moderately labile P was most strongly associated with high total Al & Fe content that we interpret to represent oxides and 1:1 clay minerals. The occluded P fraction was strongly associated...
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The Adirondack region of New York has been identified as a hot spot where high methylmercury concentrations are found in surface waters and biota, yet mercury (Hg) concentrations vary widely in this region. We collected stream and groundwater samples for Hg and organic carbon analyses across the upper Hudson River, a 493 km2 basin in the central Adirondacks to evaluate and model the sources of variation in filtered total Hg (FTHg) concentrations. Variability in FTHg concentrations during the growing seasons (May-Oct) of 2007-2009 in Fishing Brook, a 66-km2 sub-basin, was better explained by specific ultra-violet absorbance at 254 nm (SUVA254), a measure of organic carbon aromaticity, than by dissolved organic carbon...
Categories: Publication; Types: Citation; Tags: Biogeochemistry
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Drainages are important features of semiarid landscapes because they are areas where surface water, groundwater, and terrestrial and aquatic ecosystems converge. Management of these critical ecohydrological systems requires a sound understanding of surface water-groundwater interactions. At the basin- to landscape-scale, drainage density, location, and channel characteristics are formed upon a geomorphic and geologic template that limit where and how surface water-groundwater interactions occur. At smaller scales, semiarid surface water-groundwater interactions exhibit a high degree of temporal and spatial variability that links directly to biogeochemical characteristics and ecosystem dynamics. In this paper, we...
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In this study, we conducted rainfall simulation experiments in a cool desert ecosystem to examine the role of biological soil crust disturbance and composition on dissolved and sediment C and N losses. We compared runoff and sediment C and N losses from intact late-successional dark cyanolichen crusts (intact) to both trampled dark crusts (trampled) and dark crusts where the top 1 cm of the soil surface was removed (scraped). In a second experiment, we compared C and N losses in runoff and sediments in early-successional light cyanobacterial crusts (light) to that of intact late-successional dark cyanolichen crusts (dark). A relatively high rainfall intensity of approximately 38 mm per 10-min period was used to...
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The exotic annual grass Bromus tectorum has replaced thousands of hectares of native perennial vegetation in semi-arid ecosystems of the western United States. Inorganic N availability and production were compared in soil from monodominant patches of Bromus tectorum, the perennial bunchgrass Elymus elymoides, and the shrub Artemisia tridentata, in Curlew Valley, a salt-desert shrub site in Northern Utah. Bromus-dominated soil had greater %N in the top 10 cm than Artemisia or Elymus-dominated soils. As determined by spring isotope-dilution assays, gross mineralization and nitrification rates were higher in Bromus-dominated than Artemisia-dominated soils, but gross rates of NH4+ and NO3- consumption were also higher....
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Organic carbon supply is linked to nitrogen transformation in ecosystems. However, the role of organic carbon quality in nitrogen processing is not as well understood. We determined how the quality of particulate organic carbon (POC) influenced nitrogen transformation in stream sediments by burying identical quantities of varying quality POC (northern red oak (Quercus rubra) leaves, red maple (Acer rubrum) leaves, red maple wood) in stream mesocosms and measuring the effects on nitrogen retention and denitrification compared to a control of combusted sand. We also determined how POC quality affected the quantity and quality of dissolved organic carbon (DOC) and dissolved oxygen concentration in groundwater. Nitrate...
Categories: Publication; Types: Citation; Tags: Biogeochemistry
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In order to determine the effect of increased nitrogen inputs on fluxed of N2O and CH4 from alpine soils, we measured fluxes of these gases from fertilized and unfertilized soils in wet and dry alpine meadows. In the dry meadow, the addition of nitrogen resulted in a 22-fold increase in N2O emissions, while in the wet meadow, we observed a 45-fold increase in N2O emission rates. CH4 uptake in the dry meadow was reduced 52% by fertilization; however, net CH4 production occurred in all the wet meadow plots and emission rates were not significantly affected by fertilization. Net nitrification rates in the dry meadow were higher in fertilized plots than in non-fertilized plots throughout the growing season; net mineralization...
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A survey of nitric oxide (NO) emission from Chihuahuan desert soils found mean NO fluxes <0.1 ng NO-N cm-2 h-1 during the dry season. These fluxes were at the lower end of the range reported for temperate grassland and woodland ecosystems. NO fluxes from wet or watered soils were higher (0.1-35 ng NO-N cm-2 h-1 ). Watering of black grama grassland soils produced an initial pulse of 12 ng cm-2 h-1 (12-h after 1-cm watering) with high fluxes sustained over 4 days with repeated watering. Initial pulses from shrubland soils were lower (maximum 5 ng cm-2 h-1 ), and fluxes declined with repeated watering. Repeated watering of creosotebush soils depleted the soil NH4 + pool, and NO emissions were directly related to soil...


map background search result map search result map Environmental Controls on Nitric Oxide Emission from Northern Chihuahuan Desert Soils Surface water-groundwater interactions in semiarid drainages of the American southwest Fluxes of nitrous oxide and methane from nitrogen-amended soils in a Colorado alpine ecosystem Soil Respiration in the Cold Desert Environment of the Colorado Plateau (USA): Abiotic Regulators and Thresholds Biogeochemical control of cheatgrass (Bromus tectorum) germination, emergence, and growth Chemical and textural controls on phosphorus mobility in drylands of southeastern Utah Impacts of Biological Soil Crust Disturbance and Composition on C and N Loss from Water Erosion Inorganic N turnover and availability in annual- and perennial-dominated soils in a northern Utah shrub-steppe ecosystem NO gas loss from biologically crusted soils in Canyonlands National Park, Utah Identification of nitrogen sources to four small lakes in the agricultural region of Khorezm, Uzbekistan Specific ultra-violet absorbance as an indicator measurement of merucry sources in an Adirondack River basin Particulate organic matter quality influences nitrate retention and denitrification in stream sediments: evidence from a carbon burial experiment Atmospheric deposition and solute export in giant sequoia: mixed conifer watersheds in the Sierra Nevada, California Ice2O: A Continued Assessment of Icefield-to-Ocean Change in the Pacific Coastal Temperate Rainforest Isotopic and chemical composition (δ13C, Δ14C, δ15N, C:N, SUVA254nm, % HPOA) of aquatic carbon and field conditions (water temperature, pH, discharge) in the Upper Mississippi River Basin, October 2014 – February 2016 Cottonwood Lake Study Area - Water Chemistry - Wetlands Cottonwood Lake Study Area - Water Chemistry - Wells Suisun Marsh, CA:  Net Ecosystem Carbon Balance Data for Biogeochemical and Physical Processes Controlling Mercury Methylation and Bioaccumulation in Lake Powell, Glen Canyon National Recreation Area, Utah and Arizona, 2014-2015 USGS Measurements of Dissolved and Suspended Particulate Material Selenium in Lake Koocanusa in the Vicinity of Libby Dam (MT), 2015-2016 Cottonwood Lake Study Area - Water Chemistry - Wetlands Cottonwood Lake Study Area - Water Chemistry - Wells Atmospheric deposition and solute export in giant sequoia: mixed conifer watersheds in the Sierra Nevada, California Fluxes of nitrous oxide and methane from nitrogen-amended soils in a Colorado alpine ecosystem Suisun Marsh, CA:  Net Ecosystem Carbon Balance Particulate organic matter quality influences nitrate retention and denitrification in stream sediments: evidence from a carbon burial experiment Soil Respiration in the Cold Desert Environment of the Colorado Plateau (USA): Abiotic Regulators and Thresholds Biogeochemical control of cheatgrass (Bromus tectorum) germination, emergence, and growth Chemical and textural controls on phosphorus mobility in drylands of southeastern Utah Impacts of Biological Soil Crust Disturbance and Composition on C and N Loss from Water Erosion NO gas loss from biologically crusted soils in Canyonlands National Park, Utah Data for Biogeochemical and Physical Processes Controlling Mercury Methylation and Bioaccumulation in Lake Powell, Glen Canyon National Recreation Area, Utah and Arizona, 2014-2015 Inorganic N turnover and availability in annual- and perennial-dominated soils in a northern Utah shrub-steppe ecosystem Isotopic and chemical composition (δ13C, Δ14C, δ15N, C:N, SUVA254nm, % HPOA) of aquatic carbon and field conditions (water temperature, pH, discharge) in the Upper Mississippi River Basin, October 2014 – February 2016 Identification of nitrogen sources to four small lakes in the agricultural region of Khorezm, Uzbekistan Surface water-groundwater interactions in semiarid drainages of the American southwest Specific ultra-violet absorbance as an indicator measurement of merucry sources in an Adirondack River basin Ice2O: A Continued Assessment of Icefield-to-Ocean Change in the Pacific Coastal Temperate Rainforest