Effects of imposed salinity gradients on dissimilatory arsenate reduction, sulfate reduction, and other microbial processes in sediments from two California soda lakes
T.R. Kulp, S. Han, C.W. Saltikov, B.D. Lanoil, K. Zargar, Ron Oremland
2007, Applied and Environmental Microbiology (73) 5130-5137
Salinity effects on microbial community structure and on potential rates of arsenate reduction, arsenite oxidation, sulfate reduction, denitrification, and methanogenesis were examined in sediment slurries from two California soda lakes. We conducted experiments with Mono Lake and Searles Lake sediments over a wide range of salt concentrations...
Dams, floodplain land use, and riparian forest conservation in the semiarid Upper Colorado River Basin, USA
D.C. Andersen, D.J. Cooper, K. Northcott
2007, Environmental Management (40) 453-475
Land and water resource development can independently eliminate riparian plant communities, including Fremont cottonwood forest (CF), a major contributor to ecosystem structure and functioning in semiarid portions of the American Southwest. We tested whether floodplain development was linked to river regulation in the Upper Colorado River Basin (UCRB) by relating...
Simulation of submarine groundwater discharge salinity and temperature variations: Implications for remote detection
A.M. Dausman, C.D. Langevin, M.C. Sukop
2007, Conference Paper, IAHS-AISH Publication
A hydrological analysis using a numerical simulation was done to identify the transient response of the salinity and temperature of submarine groundwater discharge (SGD) and utilize the results to guide data collection. Results indicate that the amount of SGD fluctuates depending on the ocean stage and geology, with the greatest...
Efficiency of conventional drinking-water-treatment processes in removal of pharmaceuticals and other organic compounds
Paul E. Stackelberg, Jacob Gibs, Edward T. Furlong, Michael T. Meyer, Steven D. Zaugg, R.L. Lippincott
2007, Science of the Total Environment (377) 255-272
Samples of water and sediment from a conventional drinking-water-treatment (DWT) plant were analyzed for 113 organic compounds (OCs) that included pharmaceuticals, detergent degradates, flame retardants and plasticizers, polycyclic aromatic hydrocarbons (PAHs), fragrances and flavorants, pesticides and an insect repellent, and plant and animal steroids. 45 of these compounds were detected...
Groundwater noble gas, age, and temperature signatures in an Alpine watershed: Valuable tools in conceptual model development
Andrew H. Manning, Jonathan S. Caine
2007, Water Resources Research (43)
Bedrock groundwater in alpine watersheds is poorly understood, mainly because of a scarcity of wells in alpine settings. Groundwater noble gas, age, and temperature data were collected from springs and wells with depths of 3–342 m in Handcart Gulch, an alpine watershed in Colorado. Temperature profiles indicate active groundwater circulation...
Groundwater flow with energy transport and water-ice phase change: Numerical simulations, benchmarks, and application to freezing in peat bogs
J.M. McKenzie, Clifford I. Voss, D. I. Siegel
2007, Advances in Water Resources (30) 966-983
In northern peatlands, subsurface ice formation is an important process that can control heat transport, groundwater flow, and biological activity. Temperature was measured over one and a half years in a vertical profile in the Red Lake Bog, Minnesota. To successfully simulate the transport of heat within the peat profile,...
The chemical response of particle-associated contaminants in aquatic sediments to urbanization in New England, U.S.A.
A.T. Chalmers, P. C. Van Metre, E. Callender
2007, Journal of Contaminant Hydrology (91) 4-25
Relations between urbanization and particle-associated contaminants in New England were evaluated using a combination of samples from sediment cores, streambed sediments, and suspended stream sediments. Concentrations of PAHs, PCBs, DDT, and seven trace metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) were correlated strongly with urbanization, with the strongest relations...
Ground water stratification and delivery of nitrate to an incised stream under varying flow conditions
John Karl Bohlke, M. E. O’Connell, K.L. Prestegaard
2007, Journal of Environmental Quality (36) 664-680
Ground water processes affecting seasonal variations of surface water nitrate concentrations were investigated in an incised first-order stream in an agricultural watershed with a riparian forest in the coastal plain of Maryland. Aquifer characteristics including sediment stratigraphy, geochemistry, and hydraulic properties were examined in combination with chemical and isotopic analyses...
Eogenetic karst hydrology: Insights from the 2004 hurricanes, peninsular Florida
L.J. Florea, H. Leonard Vacher
2007, Ground Water (45) 439-446
Eogenetic karst lies geographically and temporally close to the depositional environment of limestone in warm marine water at low latitude, in areas marked by midafternoon thunderstorms during a summer rainy season. Spring hydrographs from such an environment in north-central Florida are characterized by smooth, months-long, seasonal maxima. The passage of...
Using biodynamic models to reconcile differences between laboratory toxicity tests and field biomonitoring with aquatic insects
D.B. Buchwalter, Daniel J. Cain, W.H. Clements, S. N. Luoma
2007, Environmental Science & Technology (41) 4821-4828
Aquatic insects often dominate lotic ecosystems, yet these organisms are under-represented in trace metal toxicity databases. Furthermore, toxicity data for aquatic insects do not appear to reflect their actual sensitivities to metals in nature, because the concentrations required to elicit toxicity...
The influence of river regulation and land use on floodplain forest regeneration in the semi-arid upper Colorado River Basin, USA
K. Northcott, D.C. Andersen, D.J. Cooper
2007, River Research and Applications (23) 565-577
Flow regulation effects on floodplain forests in the semi-arid western United States are moderately well understood, whereas effects associated with changes in floodplain land use are poorly documented. We mapped land cover patterns from recent aerial photos and applied a classification scheme to mainstem alluvial floodplains in 10 subjectively selected...
Simple predictions of maximum transport rate in unsaturated soil and rock
John R. Nimmo
2007, Water Resources Research (43)
In contrast with the extreme variability expected for water and contaminant fluxes in the unsaturated zone, evidence from 64 field tests of preferential flow indicates that the maximum transport speed Vmax, adjusted for episodicity of infiltration, deviates little from a geometric mean of 13 m/d. A model based on constant‐speed travel...
Concentrations of metals in water, sediment, biofilm, benthic macroinvertebrates, and fish in the Boulder River watershed, Montana, and the role of colloids in metal uptake
Aida Farag, David A. Nimick, Briant A. Kimball, Stanley E. Church, David D. Harper, William G. Brumbaugh
2007, Archives of Environmental Contamination and Toxicology (52) 397-409
To characterize the partitioning of metals in a stream ecosystem, concentrations of trace metals including As, Cd, Cu, Pb, and Zn were measured in water, colloids, sediment, biofilm (also referred to as aufwuchs), macroinvertebrates, and fish collected from the Boulder River watershed, Montana. Median concentrations of Cd, Cu, and...
The oxygen-18 isotope approach for measuring aquatic metabolism in high-productivity waters
Craig R. Tobias, John Karl Bohlke, Judson W. Harvey
2007, Limnology and Oceanography (52) 1439-1453
We examined the utility of δ18O2 measurements in estimating gross primary production (P), community respiration (R), and net metabolism (P : R) through diel cycles in a productive agricultural stream located in the midwestern U.S.A. Large diel swings in O2(±200 µmol L−1) were accompanied by large diel variation in δ18O2 (±10‰). Simultaneous...
Anaerobic biodegradation and hydrogeochemical controls on natural attenuation of trichloroethene in an inland forested wetland
M.M. Lorah, L.J. Dyer, D.R. Burris
2007, Bioremediation Journal (11) 85-102
Anaerobic biodegradation was conducted in a forested wetland where a plume of trichloroethylene discharges from a sand aquifer through organic-rich wetland and stream-bottom sediments. The rapid response of the wetland hydrology to precipitation events altered groundwater flow and geochemistry during wet conditions in the spring compared to the drier conditions...
Mars reconnaissance orbiter's high resolution imaging science experiment (HiRISE)
Alfred S. McEwen, Eric M. Eliason, James W. Bergstrom, Nathan T. Bridges, Candice J. Hansen, W. Alan Delamere, John A. Grant, Virginia C. Gulick, Kenneth E. Herkenhoff, Laszlo P. Keszthelyi, Randolph L. Kirk, Michael T. Mellon, Steven W. Squyres, Nicolas Thomas, Catherine M. Weitz
2007, Journal of Geophysical Research E: Planets (112)
The HiRISE camera features a 0.5 m diameter primary mirror, 12 m effective focal length, and a focal plane system that can acquire images containing up to 28 Gb (gigabits) of data in as little as 6 seconds. HiRISE will provide detailed images (0.25 to 1.3 m/pixel) covering ∼1% of...
Biotransformation of caffeine, cotinine, and nicotine in stream sediments: Implications for use as wastewater indicators
Paul M. Bradley, Larry B. Barber, Dana W. Kolpin, Peter B. McMahon, Francis H. Chapelle
2007, Environmental Toxicology and Chemistry (26) 1116-1121
Microbially catalyzed cleavage of the imadazole ring of caffeine was observed in stream sediments collected upstream and downstream of municipal wastewater treatment plants (WWTP) in three geographically separate stream systems. Microbial demethylation of the N-methyl component of cotinine and its metabolic precursor, nicotine, also was observed in these sediments. These...
Formation of tellurium nanocrystals during anaerobic growth of bacteria that use Te oxyanions as respiratory electron acceptors
Shaun M. Baesman, Thomas D. Bullen, J. Dewald, Donghui Zhang, S. Curran, F.S. Islam, T.J. Beveridge, Ronald S. Oremland
2007, Applied and Environmental Microbiology (73) 2135-2143
Certain toxic elements support the metabolism of diverse prokaryotes by serving as respiratory electron acceptors for growth. Here, we demonstrate that two anaerobes previously shown to be capable of respiring oxyanions of selenium also achieve growth by reduction of either tellurate [Te(VI)] or tellurite [Te(IV)] to elemental...
Effects of intraborehole flow on groundwater age distribution
B.A. Zinn, Leonard F. Konikow
2007, Hydrogeology Journal (15) 633-643
Environmental tracers are used to estimate groundwater ages and travel times, but the strongly heterogeneous nature of many subsurface environments can cause mixing between waters of highly disparate ages, adding additional complexity to the age-estimation process. Mixing may be exacerbated by the presence of wells because long open intervals or...
Field-derived relationships for flow velocity and resistance in high-gradient streams
F. Comiti, L. Mao, A. Wilcox, E.E. Wohl, M.A. Lenzi
2007, Journal of Hydrology (340) 48-62
We measured velocity and channel geometry in 10 reaches (bed gradient = 0.08-0.21) of a predominantly step-pool channel, the Rio Cordon, Italy, over a range of discharges (3-80% of the bankfull discharge). The resulting data were used to compute flow resistance. At-a-station hydraulic geometry relations indicate that in most reaches,...
Determining metal assimilation efficiency in aquatic invertebrates using enriched stable metal isotope tracers
Marie Noele Croteau, Samuel N. Luoma, B. Pellet
2007, Aquatic Toxicology (83) 116-125
We employ a novel approach that combines pulse-chase feeding and multi-labelled stable isotopes to determine gut passage time (GPT), gut retention time (GRT), food ingestion rate (IR) and assimilation efficiency (AE) of three trace elements for a freshwater gastropod. Lettuce isotopically enriched in 53Cr, 65Cu and 106Cd was fed for 2 h to Lymnaea stagnalis....
Geoelectrical evidence of bicontinuum transport in groundwater
K. Singha, Frederick D. Day-Lewis, John W. Lane Jr.
2007, Geophysical Research Letters (34)
Bicontinuum models and rate-limited mass transfer (RLMT) explain complex transport behavior (e.g., long tailing and rebound) in heterogeneous geologic media, but experimental verification is problematic because geochemical samples represent the mobile component of the pore space. Here, we present geophysical evidence of RLMT at the field scale during an aquifer-storage...
Increased groundwater to stream discharge from permafrost thawing in the Yukon River basin: Potential impacts on lateral export of carbon and nitrogen
Michelle Ann Walvoord, Robert G. Striegl
2007, Geophysical Research Letters (34)
Arctic and subarctic watersheds are undergoing climate warming, permafrost thawing, and thermokarst formation resulting in quantitative shifts in surface water - groundwater interaction at the basin scale. Groundwater currently comprises almost one fourth of Yukon River water discharged to the Bering Sea and contributes 5-10% of the dissolved organic carbon...
Altered stream-flow regimes and invasive plant species: The Tamarix case
J.C. Stromberg, S.J. Lite, R. Marler, C. Paradzick, P.B. Shafroth, D. Shorrock, J. M. White, M.S. White
2007, Global Ecology and Biogeography (16) 381-393
Aim: To test the hypothesis that anthropogenic alteration of stream-flow regimes is a key driver of compositional shifts from native to introduced riparian plant species. Location: The arid south-western United States; 24 river reaches in the Gila and Lower Colorado drainage basins of Arizona. Methods: We compared the abundance of...
Origin of halite brine in the Onondaga Trough near Syracuse, New York State, USA: Modeling geochemistry and variable-density flow
Richard M. Yager, William M. Kappel, Niel Plummer
2007, Hydrogeology Journal (15) 1321-1339
Halite brine (saturation ranging from 45 to 80%) lies within glacial sediments that fill the Onondaga Trough, a bedrock valley deepened by Pleistocene glaciation near Syracuse, New York State, USA. The most concentrated brine occupies the northern end of the trough, about 10 km downgradient of the northern limit of...
