Phosphate oxygen isotope ratios as a tracer for sources and cycling of phosphate in North San Francisco Bay, California
K. McLaughlin, C. Kendall, S. R. Silva, M. Young, A. Paytan
2006, Journal of Geophysical Research G: Biogeosciences (111)
[1] A seasonal analysis assesing variations in the oxygen isotopic composition of dissolved inorganic phosphate (DIP) was conducted in the San Francisco Bay estuarine system, California. Isotopic fractionation of oxygen in DIP (exchange of oxygen between phosphate and environmental water) at surface water temperatures occurs only as...
Step wise, multiple objective calibration of a hydrologic model for a snowmelt dominated basin
L.E. Hay, G.H. Leavesley, M.P. Clark, S.L. Markstrom, Roland J. Viger, M. Umemoto
2006, Journal of the American Water Resources Association (42) 877-890
The ability to apply a hydrologic model to large numbers of basins for forecasting purposes requires a quick and effective calibration strategy. This paper presents a step wise, multiple objective, automated procedure for hydrologic model calibration. This procedure includes the sequential calibration of a model's simulation of solar radiation (SR),...
Effects of long-term water table drawdown on evapotranspiration and vegetation in an arid region phreatophyte community
D.J. Cooper, J.S. Sanderson, D.I. Stannard, D.P. Groeneveld
2006, Journal of Hydrology (325) 21-34
Evapotranspiration rates and the ground water component of evapotranspiration at a site in Colorado's San Luis Valley that is dominated by shrubby phreatophytes (greasewood and rabbitbrush) were compared before and after a water table drawdown. Evapotranspiration (ET) rates at the site were first measured in 1985-1987 (pre-drawdown) when the mean...
Effects of hurricanes Katrina and Rita on the chemistry of bottom sediments in Lake Pontchartrain, Louisiana, USA
P. C. Van Metre, A. J. Horowitz, B.J. Mahler, W.T. Foreman, C. C. Fuller, M.R. Burkhardt, K. A. Elrick, E. T. Furlong, S. C. Skrobialowski, J.J. Smith, J.T. Wilson, S.D. Zaugg
2006, Environmental Science & Technology (40) 6894-6902
The effects of Hurricanes Katrina and Rita and the subsequent unwatering of New Orleans, Louisiana, on the sediment chemistry of Lake Pontchartrain were evaluated by chemical analysis of samples of street mud and suspended and bottom sediments. The highest concentrations of urban-related elements and compounds (e.g., Pb,...
A 16-year record of eolian dust in Southern Nevada and California, USA: Controls on dust generation and accumulation
M.C. Reheis
2006, Journal of Arid Environments (67) 487-520
An ongoing project monitors modern dust accumulation in the arid southwestern United States to (1) determine the rate and composition of dust inputs to soils and (2) relate dust accumulation to weather patterns to help predict the effects of climate change on dust production and accumulation. The 16-year records of...
Tracer test with As(V) under variable redox conditions controlling arsenic transport in the presence of elevated ferrous iron concentrations
R. Hohn, M. Isenbeck-Schroter, D.B. Kent, J.A. Davis, R. Jakobsen, S. Jann, V. Niedan, C. Scholz, S. Stadler, A. Tretner
2006, Journal of Contaminant Hydrology (88) 36-54
To study transport and reactions of arsenic under field conditions, a small-scale tracer test was performed in an anoxic, iron-reducing zone of a sandy aquifer at the USGS research site on Cape Cod, Massachusetts, USA. For four weeks, a stream of groundwater with added As(V) (6.7 μM) and bromide...
Environmental and geochemical record of human-induced changes in C storage during the last millennium in a temperate wetland (Las Tablas de Daimiel National Park, central Spain)
F. Dominguez-Castro, J.I. Santisteban, R. Mediavilla, W.E. Dean, E. Lopez-Pamo, M. J. Gil-Garcia, M. B. Ruiz-Zapata
2006, Conference Paper, Tellus, Series B: Chemical and Physical Meteorology
Las Tablas de Daimiel National Park has experienced many hydrological and ecological modifications through out its history, both of natural as well as anthropogenic origin, which have affected its carbon storage capacity and carbon fluxes. The study of those variations has been carried out by the analysis of its sedimentary...
Development of the performance confirmation program at YUCCA mountain, nevada
G.D. LeCain, D. Barr, D. Weaver, R. Snell, S.W. Goodin, F.D. Hansen
2006, Conference Paper, Proceedings of the 11th International High Level Radioactive Waste Management Conference, IHLRWM
The Yucca Mountain Performance Confirmation program consists of tests, monitoring activities, experiments, and analyses to evaluate the adequacy of assumptions, data, and analyses that form the basis of the conceptual and numerical models of flow and transport associated with a proposed radioactive waste repository at Yucca Mountain, Nevada. The Performance...
Use of borehole radar tomography to monitor steam injection in fractured limestone
C. Gregoire, P. K. Joesten
2006, Near Surface Geophysics (4) 355-365
Borehole radar tomography was used as part of a pilot study to monitor steam‐enhanced remediation of a fractured limestone contaminated with volatile organic compounds at the former Loring Air Force Base, Maine, USA. Radar tomography data were collected using 100‐MHz electric‐dipole antennae before and during steam injection to evaluate whether...
Aspects of the biology of Salicornia bigelovii torr. In relation to a proposed restoration of a wind-tidal flat system on the South Texas, USA Coast
C.P. Onuf
2006, Wetlands (26) 649-666
Wind-tidal flats are the dominant coastal wetland type in southern Texas USA. Succulent vascular plants are colonizing the flats in some locations, often where past dredge disposal along navigation channels and other activities have interrupted natural water communication between hypersaline bays and large areas of wind-tidal flats. The objective of...
Denitrification in nitrate-rich streams: Application of N2:Ar and 15N-tracer methods in intact cores
Lesley K. Smith, M.A. Voytek, J.K. Böhlke, J. W. Harvey
2006, Ecological Applications (16) 2191-2207
Rates of benthic denitrification were measured using two techniques, membrane inlet mass spectrometry (MIMS) and isotope ratio mass spectrometry (IRMS), applied to sediment cores from two NO3−‐rich streams draining agricultural land in the upper Mississippi River Basin. Denitrification was estimated simultaneously from measurements of N2:Ar (MIMS) and 15N[N2]...
Survey of organic wastewater contaminants in biosolids destined for land application
C.A. Kinney, E. T. Furlong, S.D. Zaugg, M.R. Burkhardt, S.L. Werner, J.D. Cahill, G.R. Jorgensen
2006, Environmental Science & Technology (40) 7207-7215
In this study, the presence, composition, and concentrations of organic wastewater contaminants (OWCs) were determined in solid materials produced during wastewater treatment. This study was undertaken to evaluate the potential of these solids, collectively referred to as biosolids, as a source of OWCs to soil and water...
Occurrence and fate of organic contaminants during onsite wastewater treatment
K.E. Conn, L. B. Barber, G.K. Brown, R.L. Siegrist
2006, Environmental Science & Technology (40) 7358-7366
Onsite wastewater treatment systems serve approximately 25% of the U.S. population. However, little is known regarding the occurrence and fate of organic wastewater contaminants (OWCs), including endocrine disrupting compounds, during onsite treatment. A range of OWCs including surfactant metabolites, steroids, stimulants, metal-chelating agents, disinfectants, antimicrobial agents, and...
Factors influencing soil invertebrate communities in riparian grasslands of the central platte river floodplain
C.A. Davis, J. E. Austin, D. A. Buhl
2006, Wetlands (26) 438-454
In the Platte River Valley of central Nebraska, USA, riparian grasslands (also known as wet meadows) have been severely impacted by a reduction in river flows, causing lower ground-water levels and altered seasonal hydroperiods. The potential impacts of these hydrologic changes, as well as the environmental factors that influence wet...
New ghost-node method for linking different models with varied grid refinement
S.C. James, J.E. Dickinson, S.W. Mehl, M. C. Hill, S. A. Leake, G.A. Zyvoloski, A.-A. Eddebbarh
2006, Conference Paper, Proceedings of the 11th International High Level Radioactive Waste Management Conference, IHLRWM
A flexible, robust method for linking grids of locally refined ground-water flow models constructed with different numerical methods is needed to address a variety of hydrologic problems. This work outlines and tests a new ghost-node model-linking method for a refined "child" model that is contained within a larger and coarser...
Testing of stack-unit/aquifer sensitivity analysis using contaminant plume distribution in the subsurface of Savannah River Site, South Carolina, USA
J.M. Rine, J.M. Shafer, E. Covington, R. C. Berg
2006, Hydrogeology Journal (14) 1620-1634
Published information on the correlation and field-testing of the technique of stack-unit/aquifer sensitivity mapping with documented subsurface contaminant plumes is rare. The inherent characteristic of stack-unit mapping, which makes it a superior technique to other analyses that amalgamate data, is the ability to deconstruct the sensitivity analysis on a unit-by-unit...
Location and timing of river-aquifer exchanges in six tributaries to the Columbia River in the Pacific Northwest of the United States
C.P. Konrad
2006, Journal of Hydrology (329) 444-470
The flow of water between rivers and contiguous aquifers influences the quantity and quality of water resources, particularly in regions where precipitation and runoff are unevenly distributed through the year, such as the Columbia Basin (CB) in northwestern United States. Investigations of basin hydrogeology and gains and losses of streamflow...
Modeling the influence of river rehabilitation scenarios on bed material sediment flux in a large river over decadal timescales
Michael B. Singer, Thomas Dunne
2006, Water Resources Research (42)
A stochastic flood generator and calibrated sediment transport formulae were used to assess the decadal impact of major river rehabilitation strategies on two fraction bed material sediment flux and net storage, first‐order indicators of aquatic riverine habitat, in a large river system. Model boundary conditions were modified to reflect the...
DNA damage and external lesions in brown bullheads (Ameiurus nebulosus) from contaminated habitats
X. Yang, J. Meier, L. Chang, M. Rowan, P. C. Baumann
2006, Environmental Toxicology and Chemistry (25) 3035-3038
The Comet assay was used to compare levels of DNA damage in brown bullheads (Ameiurus nebulosus) collected from three known contaminated locations, the Cuyahoga River (OH, USA), Ashtabula River (OH, USA; both tributaries to Lake Erie, USA), and Ashumet Pond (Cape Cod, MA, USA), with brown...
Applications of GIS and database technologies to manage a Karst Feature Database
Y. Gao, R.G. Tipping, E.C. Alexander Jr.
2006, Journal of Cave and Karst Studies (68) 144-152
This paper describes the management of a Karst Feature Database (KFD) in Minnesota. Two sets of applications in both GIS and Database Management System (DBMS) have been developed for the KFD of Minnesota. These applications were used to manage and to enhance the usability of the KFD. Structured Query Language...
Light-mediated Zn uptake in photosynthetic biofilm
J.M. Morris, A.M. Farag, D. A. Nimick, J.S. Meyer
2006, Hydrobiologia (571) 361-371
Our experiments conducted under controlled laboratory conditions demonstrate diel uptake and release of zinc (Zn) in lab-cultured biofilm exposed to Zn concentrations that are present in some mining-impacted streams (1–2 mg Zn/l). Specifically, at constant pH, temperature, and aqueous Zn concentrations in the exposure water, biofilm accumulated Zn during the light...
Hyporheic exchange and fulvic acid redox reactions in an alpine stream/wetland ecosystem, Colorado front range
Matthew P. Miller, Diane M. McKnight, R.M. Cory, Mark W. Williams, Robert L. Runkel
2006, Environmental Science & Technology (40) 5943-5949
The influence of hyporheic zone interactions on the redox state of fulvic acids and other redox active species was investigated in an alpine stream and adjacent wetland, which is a more reducing environment. A tracer injection experiment using bromide (Br-) was conducted in the stream system. Simulations...
Global synthesis of groundwater recharge in semiarid and arid regions
Bridget R. Scanlon, K.E. Keese, A. L. Flint, L. E. Flint, C.B. Gaye, W.M. Edmunds, I. Simmers
2006, Hydrological Processes (20) 3335-3370
Global synthesis of the findings from ∼140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many...
Late Holocene lake-level fluctuations in Walker Lake, Nevada, USA
F. Yuan, B.K. Linsley, S. S. Howe, S.P. Lund, J. P. McGeehin
2006, Palaeogeography, Palaeoclimatology, Palaeoecology (240) 497-507
Walker Lake, a hydrologically closed, saline, and alkaline lake, is situated along the western margin of the Great Basin in Nevada of the western United States. Analyses of the magnetic susceptibility (??), total inorganic carbon (TIC), and oxygen isotopic composition (??18O) of carbonate sediments including ostracode shells (Limnocythere ceriotuberosa) from...
Intradaily variability of water quality in a shallow tidal lagoon: Mechanisms and implications
L.V. Lucas, D.M. Sereno, J.R. Burau, T.S. Schraga, C.B. Lopez, M.T. Stacey, K.V. Parchevsky, V.P. Parchevsky
2006, Estuaries and Coasts (29) 711-730
Although surface water quality and its underlying processes vary over time scales ranging from seconds to decades, they have historically been studied at the lower (weekly to interannual) frequencies. The aim of this study was to investigate intradaily variability of three water quality parameters in a small freshwater tidal...
