Comparative performance of fixed-film biological filters: Application of reactor theory
B.J. Watten, P.L. Sibrell
2006, Aquacultural Engineering (34) 198-213
Nitrification is classified as a two-step consecutive reaction where R1 represents the rate of formation of the intermediate product NO2-N and R2 represents the rate of formation of the final product NO3-N. The relative rates of R1 and R2 are influenced by reactor type characterized hydraulically as plug-flow, plug-flow with...
Microbial transformations of arsenic in the environment: From soda lakes to aquifers
J.R. Lloyd, R.S. Oremland
2006, Elements (2) 85-90
Arsenic is a highly toxic element that supports a surprising range of biogeochemical transformations. The biochemical basis of these microbial interactions is described, with an emphasis on energy-yielding redox biotransformations that cycle between the As5+ and As3+ oxidation states. The subsequent impact of As3+-oxidising and As 5+-reducing prokaryotes on the...
Inverse modeling for seawater intrusion in coastal aquifers: Insights about parameter sensitivities, variances, correlations and estimation procedures derived from the Henry problem
E. Sanz, C.I. Voss
2006, Advances in Water Resources (29) 439-457
Inverse modeling studies employing data collected from the classic Henry seawater intrusion problem give insight into several important aspects of inverse modeling of seawater intrusion problems and effective measurement strategies for estimation of parameters for seawater intrusion. Despite the simplicity of the Henry problem, it embodies the behavior of a...
Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil
W. Borken, E.A. Davidson, K. Savage, E.T. Sundquist, P. Steudler
2006, Soil Biology and Biochemistry (38) 1388-1395
Soil moisture strongly controls the uptake of atmospheric methane by limiting the diffusion of methane into the soil, resulting in a negative correlation between soil moisture and methane uptake rates under most non-drought conditions. However, little is known about the effect of water stress on methane uptake in temperate forests...
The allometric relationship between resting metabolic rate and body mass in wild waterfowl (Anatidae) and an application to estimation of winter habitat requirements
M. R. Miller, J. McA Eadie
2006, Condor (108) 166-177
Breeding densities and migration periods of Common Snipe in Colorado were investigated in 1974-75. Sites studied were near Fort Collins and in North Park, both in north central Colorado; in the Yampa Valley in northwestern Colorado; and in the San Luis Valley in south central Colorado....Estimated densities of breeding snipe...
Seasonal migration and environmental conditions of Pacific halibut Hippoglossus stenolepis, elucidated from pop-up archival transmitting (PAT) tags
Timothy Loher, Andrew C. Seitz
2006, Marine Ecology Progress Series (317) 259-271
Pop-up archival transmitting (PAT) tags were used to study the fall migration of halibut in the Gulf of Alaska (GOA). We tagged 6 Pacific halibut Hippoglossus stenolepis on summer feeding grounds in the eastern GOA and another 6 in the western GOA from June 13 to August 6, 2002. The...
Application of artificial neural networks to assess pesticide contamination in shallow groundwater
G.B. Sahoo, C. Ray, E. Mehnert, D.A. Keefer
2006, Science of the Total Environment (367) 234-251
In this study, a feed-forward back-propagation neural network (BPNN) was developed and applied to predict pesticide concentrations in groundwater monitoring wells. Pesticide concentration data are challenging to analyze because they tend to be highly censored. Input data to the neural network included the categorical indices of depth to aquifer material,...
Effects of nest density, location, and timing on breeding success of Caspian Terns
Michelle Antolos, D.D. Roby, Donald E. Lyons, Scott K. Anderson, K. Collis
2006, Waterbirds (29) 465-472
One of the proposed benefits of colonial nesting in birds is the protection afforded against avian predators. This advantage may be counter-balanced by the negative effects of intraspecific aggression on breeding success. Effects of nest density, nest location within the colony, and timing of nest initiation on productivity of Caspian...
Modeling the effect of varying swim speeds on fish passage through velocity barriers
T. Castro-Santos
2006, Transactions of the American Fisheries Society (135) 1230-1237
The distance fish can swim through zones of high-velocity flow is an important factor limiting the distribution and conservation of riverine and diadromous fishes. Often, these barriers are characterized by nonuniform flow conditions, and it is likely that fish will swim at varying speeds to traverse them. Existing models used...
Emplacement of subaerial pahoehoe lava sheet flows into water: 1990 Kūpaianaha flow of Kilauea volcano at Kaimū Bay, Hawai`i
Susumu Umino, Miyuki Nonaka, James P. Kauahikaua
2006, Bulletin of Volcanology (69) 125-139
Episode 48 of the ongoing eruption of Kilauea, Hawai`i, began in July 1986 and continuously extruded lava for the next 5.5 years from a low shield, Kūpaianaha. The flows in March 1990 headed for Kalapana and inundated the entire town under 15–25 m of lava by the end of August. As the...
Geochemical evolution of solutions derived from experimental weathering of sulfide-bearing rocks
L. Munk, G. Faure, R. Koski
2006, Applied Geochemistry (21) 1123-1134
The chemical composition of natural waters is affected by the weathering of geologic materials at or near the surface of the Earth. Laboratory weathering experiments of whole-rock sulfide rocks from the Shoe-Basin Mine (SBM) and the Pennsylvania Mine (PM) from the Peru Creek Basin, Summit County, Colorado, indicate that the...
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...
Geochemistry of low-temperature springs northwest of Yellowstone caldera: Seeking the link between seismicity, deformation, and fluid flow
William C. Evans, Deborah Bergfeld, Matthias C. van Soest, Mark Huebner, John Fitzpatrick, Kinga M. Revesz
2006, Journal of Volcanology and Geothermal Research (154) 169-180
A comprehensive geochemical survey of springs outside the northwest margin of the Yellowstone caldera was undertaken in 2003 and 2004. This survey was designed to detect: (1) active leakage from a huge reservoir of CO2 gas recently postulated to extend from beneath the caldera into this area; and (2) lingering evidence...
Arsenic, cadmium, lead, and mercury in surface soils, Pueblo, Colorado: Implications for population health risk
D.M. Diawara, J.S. Litt, D. Unis, N. Alfonso, L.A. Martinez, J.G. Crock, D. B. Smith, J. Carsella
2006, Environmental Geochemistry and Health (28) 297-315
Decades of intensive industrial and agricultural practices as well as rapid urbanization have left communities like Pueblo, Colorado facing potential health threats from pollution of its soils, air, water and food supply. To address such concerns about environmental contamination, we conducted an urban geochemical study of the city of Pueblo...
Gas-water-rock interactions in Frio Formation following CO2 injection: Implications for the storage of greenhouse gases in sedimentary basins
Yousif K. Kharaka, David R. Cole, Susan D. Hovorka, W.D. Gunter, Kevin G. Knauss, Barry M. Freifeild
2006, Geology (34) 577-580
To investigate the potential for the geologic storage of CO2 in saline sedimentary aquifers, 1600 t of CO2 were injected at 1500 m depth into a 24-m-thick sandstone section of the Frio Formation, a regional brine and oil reservoir in the U.S. Gulf Coast....
Sediment mineralogy based on visible and near-infrared reflectance spectroscopy
R. D. Jarrard, Vanden Berg
Rothwell R.G., editor(s)
2006, Geological Society Special Publication 129-140
Visible and near-infrared spectroscopy (VNIS) can be used to measure reflectance spectra (wavelength 350-2500 nm) for sediment cores and samples. A local ground-truth calibration of spectral features to mineral percentages is calculated by measuring reflectance spectra for a suite of samples of known mineralogy. This approach has been tested on...
Gas hydrate transect across northern Cascadia margin
M. Riedel, T. Collett, M. Malone, F. Akiba, M. Blanc-Valleron, M. Ellis, G. Guerin, Y. Hashimoto, V. Heuer, Y. Higashi, M. Holland, P. Jackson, M. Kaneko, M. Kastner, J.-H. Kim, H. Kitajima, P. Long, A. Malinverno, Gwen E. Myers, L. Palekar, J. Pohlman, P. Schultheiss, B. Teichert, M. Torres, A. Trehu, Jingyuan Wang, U. Worthmann, H. Yoshioka
2006, Eos, Transactions, American Geophysical Union (87) 329-330
Gas hydrate is a solid compound mainly comprised of methane and water that is stable under low temperature and high pressure conditions. Usually found in offshore environments with water depths exceeding about 500 meters and in arctic regions associated with permafrost, gas hydrates form an efficient storage system for natural...
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]...
The contingent behavior of charter fishing participants on the Chesapeake Bay: Welfare estimates associated with water quality improvements
P.J. Poor, M. Breece
2006, Journal of Environmental Planning and Management (49) 265-278
Water quality in the Chesapeake Bay has deteriorated over recent years. Historically, fishing has contributed to the region's local economy in terms of commercial and recreational harvests. A contingent behavior model is used to estimate welfare measures for charter fishing participants with regard to a hypothetical improvement in water quality....
The application of acoustic Doppler current profilers to measure the timing and patterns of coral larval dispersal
Curt D. Storlazzi, E.K. Brown, Michael E. Field
2006, Coral Reefs (25) 369-381
An experiment was conducted along the reefs off west Maui, Hawaii, during the summer of 2003 to monitor the spawning of the reef-building coral Montipora capitata and to determine the role of ocean currents in dispersing the larvae from the natal reef. Instruments documented the environmental forcing during the coral...
Ground-water surface-water interactions and long-term change in riverine riparian vegetation in the southwestern United States
R. H. Webb, S. A. Leake
2006, Conference Paper, Journal of Hydrology
Riverine riparian vegetation has changed throughout the southwestern United States, prompting concern about losses of habitat and biodiversity. Woody riparian vegetation grows in a variety of geomorphic settings ranging from bedrock-lined channels to perennial streams crossing deep alluvium and is dependent on interaction between ground-water and surface-water resources. Historically, few...
Case study: Mapping tsunami hazards associated with debris flow into a reservoir
J. S. Walder, P. Watts, C. F. Waythomas
2006, Journal of Hydraulic Engineering (132) 1-11
Debris-flow generated impulse waves (tsunamis) pose hazards in lakes, especially those used for hydropower or recreation. We describe a method for assessing tsunami-related hazards for the case in which inundation by coherent water waves, rather than chaotic splashing, is of primary concern. The method involves an experimentally based initial condition...
Nitrogen loads to estuaries from waste water plumes: Modeling and isotopic approaches
K.D. Kroeger, Marci L. Cole, J.K. York, I. Valiela
2006, Ground Water (44) 188-200
We developed, and applied in two sites, novel methods to measure ground water-borne nitrogen loads to receiving estuaries from plumes resulting from land disposal of waste water treatment plant (WWTP) effluent. In addition, we quantified nitrogen losses from WWTP effluent during transport through watersheds. WWTP load to receiving water was...
Trends in the nutrient enrichment of U.S. rivers during the late 20th century and their relation to changes in probable stream trophic conditions
R. B. Alexander, R. A. Smith
2006, Conference Paper, Limnology and Oceanography
We estimated trends in concentrations of total phosphorus (TP) and total nitrogen (TN) and the related change in the probabilities of trophic conditions from 1975 to 1994 at 250 nationally representative riverine monitoring locations in the U.S. with drainage areas larger than about 1,000 km2. Statistically significant (p < 0.05)...
Aqueous processes at Gusev crater inferred from physical properties of rocks and soils along the Spirit traverse
N.A. Cabrol, J.D. Farmer, E.A. Grin, L. Ritcher, L. Soderblom, R. Li, Kenneth E. Herkenhoff, G. A. Landis, R. E. Arvidson
2006, Journal of Geophysical Research E: Planets (111)
Gusev crater was selected as the landing site for Spirit on the basis of morphological evidence of long-lasting water activity, including possibly fluvial and lacustrine episodes. From the Columbia Memorial Station to the Columbia Hills, Spirit's traverse provides a journey back in time, from relatively recent volcanic plains showing little...
