Influences of organic matter and calcification rate on trace elements in aragonitic estuarine bivalve shells
R.K. Takesue, C. R. Bacon, J.K. Thompson
2008, Geochimica et Cosmochimica Acta (72) 5431-5445
A suite of elements (B, Na, Mg, S, K, Ca, V, Mn, Cr, Sr, and Ba) was measured in aragonitic shells of the estuarine bivalve Corbula amurensis, the Asian clam, using the Sensitive High-Resolution Ion MicroProbe with Reverse Geometry (SHRIMP RG). Our initial intent...
Measuring real-time streamflow using emerging technologies: Radar, hydroacoustics, and the probability concept
J. Fulton, J. Ostrowski
2008, Journal of Hydrology (357) 1-10
Forecasting streamflow during extreme hydrologic events such as floods can be problematic. This is particularly true when flow is unsteady, and river forecasts rely on models that require uniform-flow rating curves to route water from one forecast point to another. As a result, alternative methods for measuring streamflow are needed...
Complex seasonal patterns of primary producers at the land-sea interface
J. E. Cloern, A.D. Jassby
2008, Ecology Letters (11) 1294-1303
Seasonal fluctuations of plant biomass and photosynthesis are key features of the Earth system because they drive variability of atmospheric CO2, water and nutrient cycling, and food supply to consumers. There is no inventory of phytoplankton seasonal cycles in nearshore coastal ecosystems where forcings from ocean,...
Solute profiles in soils, weathering gradients and exchange equilibrium/disequilibrium
A. F. White, M. S. Schulz, David A. Stonestrom, D.V. Vivit, J. Fitzpatrick, T. Bullen
2008, Mineralogical Magazine (72) 149-153
The spatial and temporal changes in hydrology and pore water elemental and 87/86Sr compositions were used to determine contemporary weathering rates in a 65 to 226 ky old soil chronosequence formed from granitic sediments deposited on marine terraces along coastal California. Cl-corrected Na, K and Si increased with depth denoting inputs...
Application of synchrotron methods to assess the uptake of roadway-derived Zn by earthworms in an urban soil
S.M. Lev, E. R. Landa, K. Szlavecz, R. Casey, J. Snodgrass
2008, Mineralogical Magazine (72) 191-195
The impact of human activities on biogeochemical cycles in terrestrial environments is nowhere more apparent than in urban landscapes. Trace metals, collected on roadways and transported by storm water, may contaminate soils and sediments associated with storm water management systems. These systems will accumulate metals and associated sediments may reach...
Eulerian-Lagrangian numerical scheme for simulating advection, dispersion, and transient storage in streams and a comparison of numerical methods
T.J. Cox, R.L. Runkel
2008, Journal of Environmental Engineering (134) 996-1005
Past applications of one-dimensional advection, dispersion, and transient storage zone models have almost exclusively relied on a central differencing, Eulerian numerical approximation to the nonconservative form of the fundamental equation. However, there are scenarios where this approach generates unacceptable error. A new numerical scheme for this type...
Numerical model for the uptake of groundwater contaminants by phreatophytes
M.A. Widdowson, A. El-Sayed, J. E. Landmeyer
2008, Conference Paper, WIT Transactions on Ecology and the Environment
Conventional solute transport models do not adequately account for the effects of phreatophytic plant systems on contaminant concentrations in shallow groundwater systems. A numerical model was developed and tested to simulate threedimensional reactive solute transport in a heterogeneous porous medium. Advective-dispersive transport is coupled to biodegradation, sorption, and plantbased attenuation...
Characteristics of mangrove swamps managed for mosquito control in eastern Florida, USA
B. Middleton, D. Devlin, E. Proffitt, Karen McKee, K.F. Cretini
2008, Marine Ecology Progress Series (371) 117-129
Manipulations of the vegetation and hydrology of wetlands for mosquito control are common worldwide, but these modifications may affect vital ecosystem processes. To control mosquitoes in mangrove swamps in eastern Florida, managers have used rotational impoundment management (RIM) as an alternative to the worldwide practice of mosquito ditching. Levees surround...
The persistence of lead from past gasoline emissions and mining drainage in a large riparian system: Evidence from lead isotopes in the Sacramento River, California
C.E. Dunlap, Charles N. Alpers, R. Bouse, Howard E. Taylor, D.M. Unruh, A.R. Flegal
2008, Geochimica et Cosmochimica Acta (72) 5935-5948
Lead concentrations and isotope ratios measured in river water colloids and streambed sediment samples along 426 km of the Sacramento River, California reveal that the influence of lead from the historical mining of massive sulfide deposits in the West Shasta Cu-mining district (at the...
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...
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)...
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...
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...
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...
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...
A simulation/optimization model for groundwater resources management in the Afram Plains area, Ghana
S.M. Yidana
2008, Journal of Environmental Hydrology (16) 1-14
A groundwater flow simulation model was developed using available hydrogeo logical data to A groundwater flow simulation model was developed using available hydrogeological data to describe groundwater flow in the Afram Plains area. A nonlinear optimization model was then developed and solved for the management of groundwater resources to meet...
Compound-specific stable isotopes of organic compounds from lake sediments track recent environmental changes in an alpine ecosystem, Rocky Mountain National Park, Colorado
S.K. Enders, M. Pagani, S. Pantoja, Jill Baron, A.P. Wolfe, N. Pedentchouk, L. Nunez
2008, Limnology and Oceanography (53) 1468-1478
Compound-specific nitrogen, carbon, and hydrogen isotope records from sediments of Sky Pond, an alpine lake in Rocky Mountain National Park (Colorado, United States of America), were used to evaluate factors contributing to changes in diatom assemblages and bulk organic nitrogen isotope records identified in lake sediments across Colorado, Wyoming, and...
InSAR detects possible thaw settlement in the Alaskan Arctic Coastal Plain
Russell P. Rykhus, Zhong Lu
2008, Canadian Journal of Remote Sensing (34) 100-112
Satellite interferometric synthetic aperture radar (InSAR) has proven to be an effective tool for monitoring surface deformation from volcanoes, earthquakes, landslides, and groundwater withdrawal. This paper seeks to expand the list of applications of InSAR data to include monitoring subsidence possibly associated with thaw settlement over the Alaskan Arctic Coastal...
Boulder Creek: A stream ecosystem in an urban landscape
Philip L. Verplanck, Sheila F. Murphy, Peter W. Birkeland, Pitlick John, Larry B. Barber, Travis S. Schmidt
Robert G.H. Raynolds, editor(s)
2008, Book chapter, Roaming the Rocky Mountains and environs: Geological field trips
The Boulder Creek Watershed, within the Front Range region of Colorado, is typical of many western watersheds because it is composed of a high-gradient upper reach mostly fed by snowmelt, a substantial change in gradient at the range front, and an urban corridor within the lower gradient section. A stream...
Modeling soil moisture processes and recharge under a melting snowpack
A. L. Flint, L. E. Flint, M. D. Dettinger
2008, Conference Paper, Vadose Zone Journal
Recharge into granitic bedrock under a melting snowpack is being investigated as part of a study designed to understand hydrologic processes involving snow at Yosemite National Park in the Sierra Nevada Mountains of California. Snowpack measurements, accompanied by water content and matric potential measurements of the soil under the snowpack,...
Attribution of declining Western U.S. Snowpack to human effects
D.W. Pierce, T.P. Barnett, H.G. Hidalgo, T. Das, Celine Bonfils, B.D. Santer, G. Bala, M. D. Dettinger, D.R. Cayan, A. Mirin, A.W. Wood, T. Nozawa
2008, Journal of Climate (21) 6425-6444
Observations show snowpack has declined across much of the western United States over the period 1950-99. This reduction has important social and economic implications, as water retained in the snowpack from winter storms forms an important part of the hydrological cycle and water supply in the region. A formal model-based...
Application of a geomorphic and temporal perspective to wetland management in North America
L.M. Smith, N.H. Euliss Jr., D.A. Wilcox, M.M. Brinson
2008, Wetlands (28) 563-577
The failure of managed wetlands to provide a broad suite of ecosystem services (e.g., carbon storage, wildlife habitat, ground-water recharge, storm-water retention) valuable to society is primarily the result of a lack of consideration of ecosystem processes that maintain productive wetland ecosystems or physical and social forces that restrict a...
Late Quaternary MIS 6-8 shoreline features of pluvial Owens Lake, Owens Valley, eastern California
A. S. Jayko, S.N. Bacon
2008, Conference Paper, Special Paper of the Geological Society of America
The chronologic history of pluvial Owens Lake along the eastern Sierra Nevada in Owens Valley, California, has previously been reported for the interval of time from ca. 25 calibrated ka to the present. However, the age, distribution, and paleoclimatic context of higher-elevation shoreline features have not been formally documented. We...
Fiber‐optic distributed temperature sensing: A new tool for assessment and monitoring of hydrologic processes
John W. Lane Jr., Frederick D. Day-Lewis, Carole D. Johnson, Cian B. Dawson, David L. Nelms, Cheryl A. Eddy-Miller, Jerrod D. Wheeler, Charles F. Harvey, Hanan N. Karam
2008, Conference Paper, Symposium on the Application of Geophysics to Engineering and Environmental Problems 2008
Fiber‐optic distributed temperature sensing (FO DTS) is an emerging technology for characterizing and monitoring a wide range of important earth processes. FO DTS utilizes laser light to measure temperature along the entire length of standard telecommunications optical fibers. The technology can measure temperature every meter over FO cables up to...
Application of MODFLOW’s farm process to California’s Central Valley
Claudia C. Faunt, Randall T. Hanson, Wolfgang Schmid, Kenneth Belitz
2008, Conference Paper, California Central Valley Groundwater Modeling Workshop, Proceedings
Historically, California’s Central Valley has been one of the most productive agricultural regions in the world. The Central Valley also is rapidly becoming an important area for California’s expanding urban population. During 1980–2007, the population nearly doubled in the Central Valley, increasing the competition for water. Because of the importance...
