Characterization of the shallow groundwater system in an alpine watershed: Handcart Gulch, Colorado, USA
Katherine G. Kahn, Shemin Ge, Jonathan S. Caine, A. Manning
2008, Hydrogeology Journal (16) 103-121
Water-table elevation measurements and aquifer parameter estimates are rare in alpine settings because few wells exist in these environments. Alpine groundwater systems may be a primary source of recharge to regional groundwater flow systems. Handcart Gulch is an alpine watershed in Colorado, USA comprised of highly fractured Proterozoic metamorphic and...
Multi-residue method for the analysis of 85 current-use and legacy pesticides in bed and suspended sediments
K.L. Smalling, K.M. Kuivila
2008, Journal of Chromatography A (1210) 8-18
A multi-residue method was developed for the simultaneous determination of 85 current-use and legacy organochlorine pesticides in a single sediment sample. After microwave-assisted extraction, clean-up of samples was optimized using gel permeation chromatography and either stacked carbon and alumina solid-phase extraction cartridges or a deactivated Florisil column. Analytes were determined...
Wetlands as principal zones of methylmercury production in southern Louisiana and the Gulf of Mexico region
B.D. Hall, G. R. Aiken, D. P. Krabbenhoft, M. Marvin-DiPasquale, C.M. Swarzenski
2008, Environmental Pollution (154) 124-134
It is widely recognized that wetlands, especially those rich in organic matter and receiving appreciable atmospheric mercury (Hg) inputs, are important sites of methylmercury (MeHg) production. Extensive wetlands in the southeastern United States have many ecosystem attributes ideal for promoting high MeHg production rates; however, relatively few mercury cycling studies...
Trace analysis of antidepressant pharmaceuticals and their select degradates in aquatic matrixes by LC/ESI/MS/MS
M.M. Schultz, E. T. Furlong
2008, Analytical Chemistry (80) 1756-1762
Treated wastewater effluent is a potential environmental point source for antidepressant pharmaceuticals. A quantitative method was developed for the determination of trace levels of antidepressants in environmental aquatic matrixes using solid-phase extraction coupled with liquid chromatography-electrospray ionization tandem mass spectrometry. Recoveries of parent antidepressants from matrix spiking...
Acetylene as fast food: Implications for development of life on anoxic primordial earth and in the outer solar system
R.S. Oremland, M.A. Voytek
2008, Astrobiology (8) 45-58
Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been...
A comparison of winter mercury accumulation at forested and no-canopy sites measured with different snow sampling techniques
S.J. Nelson, K.B. Johnson, K.C. Weathers, C.S. Loftin, I.J. Fernandez, J. S. Kahl, D. P. Krabbenhoft
2008, Applied Geochemistry (23) 384-398
Atmospheric mercury (Hg) is delivered to ecosystems via rain, snow, cloud/fog, and dry deposition. The importance of snow, especially snow that has passed through the forest canopy (throughfall), in delivering Hg to terrestrial ecosystems has received little attention in the literature. The snowpack...
Evapotranspiration rates and crop coefficients for a restored marsh in the Sacramento-San Joaquin Delta, California, USA
Judith Z. Drexler, Frank E. Anderson, Richard L. Snyder
2008, Hydrological Processes (22) 725-735
The surface renewal method was used to estimate evapotranspiration (ET) for a restored marsh on Twitchell Island in the Sacramento–San Joaquin Delta, California, USA. ET estimates for the marsh, together with reference ET measurements from a nearby climate station, were used to determine crop coefficients over a 3‐year period during...
Transport of elemental mercury in the unsaturated zone from a waste disposal site in an arid region
Michelle Ann Walvoord, Brian J. Andraski, D. P. Krabbenhoft, Robert G. Striegl
2008, Applied Geochemistry (23) 572-583
Mercury contained in buried landfill waste may be released via upward emission to the atmosphere or downward leaching to groundwater. Data from the US Geological Survey’s Amargosa Desert Research Site (ADRS) in arid southwestern Nevada reveal another potential pathway of Hg release: long-distance (102 m) lateral migration of elemental Hg (Hg0)...
Developing conceptual hydrogeological model for Potsdam sandstones in southwestern Quebec, Canada
Miroslav Nastev, R. Morin, Rejean Godin, Alain Rouleau
2008, Hydrogeology Journal (16) 373-388
A hydrogeological study was conducted in Potsdam sandstones on the international border between Canada (Quebec) and the USA (New York). Two sandstone formations, arkose and conglomerate (base) and well-cemented quartz arenite (upper), underlie the study area and form the major regional aquifer unit. Glacial till, littoral sand and gravel, and...
Reconstructing late Pliocene to middle Pleistocene Death Valley lakes and river systems as a test of pupfish (Cyprinodontidae) dispersal hypotheses
J.R. Knott, M. N. Machette, R.E. Klinger, A.M. Sarna-Wojcicki, J. C. Liddicoat, J. C. Tinsley III, B.T. David, V.M. Ebbs
2008, Conference Paper, Special Paper of the Geological Society of America
During glacial (pluvial) climatic periods, Death Valley is hypothesized to have episodically been the terminus for the Amargosa, Owens, and Mojave Rivers. Geological and biological studies have tended to support this hypothesis and a hydrological link that included the Colorado River, allowing dispersal of pupfish throughout southeastern California and western...
New global hydrography derived from spaceborne elevation data
B. Lehner, K.L. Verdin, A. Jarvis
2008, Eos, Transactions, American Geophysical Union (89) 93-94
To study the Earth system and to better understand the implications of global environmental change, there is a growing need for large-scale hydrographic data sets that serve as prerequisites in a variety of analyses and applications, ranging from regional watershed and freshwater conservation planning to global hydrological, climate, biogeochemical, and...
The role of hydrologic regimes on dissolved organic carbon composition in an agricultural watershed
P.J. Hernes, R.G.M. Spencer, R.Y. Dyda, B.A. Pellerin, P.A.M. Bachand, B.A. Bergamaschi
2008, Geochimica et Cosmochimica Acta (72) 5266-5277
Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled weekly in 2006 in order to investigate seasonal concentrations and compositions of dissolved organic carbon (DOC). Average DOC concentrations nearly doubled from winter baseflow (2.75 mg L-1) to summer irrigation (5.14 mg L-1), while a...
Flood trends and river engineering on the Mississippi River system
N. Pinter, A.A. Jemberie, J.W.F. Remo, R.A. Heine, B.S. Ickes
2008, Geophysical Research Letters (35)
Along >4000 km of the Mississippi River system, we document that climate, land-use change, and river engineering have contributed to statistically significant increases in flooding over the past 100-150 years. Trends were tested using a database of >8 million hydrological measurements. A geospatial database of historical engineering construction was used...
Middle to late cenozoic geology, hydrography, and fish evolution in the American Southwest
J.E. Spencer, G.R. Smith, T.E. Dowling
2008, Conference Paper, Special Paper of the Geological Society of America
An evaluation of the poorly understood Cenozoic hydrologic history of the American Southwest using combined geological and biological data yields new insights with implications for tectonic evolution. The Mesozoic Cordilleran orogen next to the continental margin of southwestern North America probably formed the continental divide. Mountain building migrated eastward to...
Dry down impacts on apple snail (Pomacea paludosa) demography: Implications for wetland water management
P.C. Darby, R.E. Bennetts, H.F. Percival
2008, Wetlands (28) 204-214
Florida apple snails (Pomacea paludosa Say) are prey for several wetland-dependent predators, most notably for the endangered Florida snail kite (Rostrhamus sociabilis Vieillot). Management concerns for kites have been raised regarding the impacts of wetland dry downs on snails, but little data exists to validate these concerns. We simulated drying...
Is there enough sand? Evaluating the fate of Grand Canyon sandbars
S.A. Wright, J. C. Schmidt, Theodore S. Melis, D.J. Topping, D. M. Rubin
2008, GSA Today (18) 4-10
Large dams have the potential to dramatically alter the flow regime, geomorphology, and aquatic ecosystem of downstream river reaches. Development of flow release regimes in order to meet multiple objectives is a challenge facing dam operators, resource managers, and scientists. Herein, we review previous work and present new analyses related...
Stream denitrification across biomes and its response to anthropogenic nitrate loading
P. J. Mulholland, A. M. Helton, G. C. Poole, R. O. Hall Jr., S. K. Hamilton, B. J. Peterson, J. L. Tank, L. R. Ashkenas, L. W. Cooper, Clifford N. Dahm, W. K. Dodds, S.E.G. Findlay, S.V. Gregory, N. B. Grimm, S. L. Johnson, W. H. McDowell, J.L. Meyer, H. M. Valett, J.R. Webster, C. P. Arango, J. J. Beaulieu, M. J. Bernot, A. J. Burgin, C. L. Crenshaw, L. T. Johnson, B.R. Niederlehner, J. M. O’Brien, J. D. Potter, R.W. Sheibley, D. J. Sobota, S. M. Thomas
2008, Nature (452) 202-205
Anthropogenic addition of bioavailable nitrogen to the biosphere is increasing and terrestrial ecosystems are becoming increasingly nitrogen-saturated, causing more bioavailable nitrogen to enter groundwater and surface waters. Large-scale nitrogen budgets show that an average of about 20-25 per cent of the nitrogen added to the biosphere is exported from rivers...
National, holistic, watershed-scale approach to understand the sources, transport, and fate of agricultural chemicals
P. D. Capel, K. A. McCarthy, J.E. Barbash
2008, Journal of Environmental Quality (37) 983-993
This paper is an introduction to the following series of papers that report on in-depth investigations that have been conducted at five agricultural study areas across the United States in order to gain insights into how environmental processes and agricultural practices interact to determine the transport and fate of agricultural...
Using heat to characterize streambed water flux variability in four stream reaches
H.I. Essaid, C.M. Zamora, K. A. McCarthy, J. R. Vogel, J.T. Wilson
2008, Journal of Environmental Quality (37) 1010-1023
Estimates of streambed water flux are needed for the interpretation of streambed chemistry and reactions. Continuous temperature and head monitoring in stream reaches within four agricultural watersheds (Leary Weber Ditch, IN; Maple Creek, NE; DR2 Drain, WA; and Merced River, CA) allowed heat to be used as a tracer to...
Hydrochemical characterization of groundwater in the Akyem area, Ghana
B. Banoeng-Yakubo, S.M. Yidana, Y. Anku, T. Akabzaa, D. Asiedu
2008, Journal of Environmental Hydrology (16) 1-12
The Akyem area is a small farming community located in southeastern Ghana. Groundwater samples from wells in the area were analyzed for concentrations of the major ions, silica, electrical conductivity and pH. The objective was to determine the main controls on the hydrochemistry of ground-water. Mass balance modeling was used...
The effects of land use on fluvial sediment chemistry for the conterminous U.S. - Results from the first cycle of the NAWQA Program: Trace and major elements, phosphorus, carbon, and sulfur
A. J. Horowitz, V. C. Stephens
2008, Science of the Total Environment (400) 290-314
In 1991, the U.S. Geological Survey (USGS) began the first cycle of its National Water Quality Assessment (NAWQA) Program. The Program encompassed 51 river basins that collectively accounted for more than 70% of the total water use (excluding power generation), and 50% of the drinking water supply in the U.S....
Effect of hydrological conditions on nitrous oxide, methane, and carbon dioxide dynamics in a bottomland hardwood forest and its implication for soil carbon sequestration
K. Yu, S.P. Faulkner, M.J. Baldwin
2008, Global Change Biology (14) 798-812
This study was conducted at three locations in a bottomland hardwood forest with a distinct elevation and hydrological gradient: ridge (high, dry), transition, and swamp (low, wet). At each location, concentrations of soil greenhouse gases (N2O, CH4, and CO2), their fluxes to the atmosphere, and soil redox potential (Eh) were...
Nitrogen fluxes through unsaturated zones in five agricultural settings across the United States
C.T. Green, L.H. Fisher, B.A. Bekins
2008, Journal of Environmental Quality (37) 1073-1085
The main physical and chemical controls on nitrogen (N) fluxes between the root zone and the water table were determined for agricultural sites in California, Indiana, Maryland, Nebraska, and Washington from 2004 to 2005. Sites included irrigated and nonirrigated fields; soil textures ranging from clay to sand; crops including corn,...
Relative importance of natural disturbances and habitat degradation on snail kite population dynamics
J. Martin, W.M. Kitchens, Christopher E. Cattau, M.K. Oli
2008, Endangered Species Research (6) 25-39
Natural disturbances and habitat degradation are major factors influencing the dynamics and persistence of many wildlife populations, yet few large-scale studies have explored the relative influence of these factors on the dynamics and persistence of animal populations. We used longterm demographic data and matrix population models to examine the potential...
Inverse geochemical modeling of groundwater evolution with emphasis on arsenic in the Mississippi River Valley alluvial aquifer, Arkansas (USA)
M.U. Sharif, R.K. Davis, K.F. Steele, B. Kim, T.M. Kresse, J.A. Fazio
2008, Journal of Hydrology (350) 41-55
Inverse geochemical modeling (PHREEQC) was used to identify the evolution of groundwater with emphasis on arsenic (As) release under reducing conditions in the shallow (25-30 m) Mississippi River Valley Alluvial aquifer, Arkansas, USA. The modeling was based on flow paths defined by high-precision (??2 cm) water level contour map; X-ray...
