Nutrient dynamics as indicators of karst processes: Comparison of the Chalk aquifer (Normandy, France) and the Edwards aquifer (Texas, U.S.A.)
B.J. Mahler, D. Valdes, M. Musgrove, N. Massei
2008, Journal of Contaminant Hydrology (98) 36-49
Karst aquifers display a range of geologic and geomorphic characteristics in a wide range of climatic and land-use settings; identification of transport dynamics representative of karst aquifers in general could help advance our understanding of these complex systems. To this end, nutrient, turbidity, and major ion dynamics in response to...
Inverse modeling of surface-water discharge to achieve restoration salinity performance measures in Florida Bay, Florida
E.D. Swain, D.E. James
2008, Journal of Hydrology (351) 188-202
The use of numerical modeling to evaluate regional water-management practices involves the simulation of various alternative water-delivery scenarios, which typically are designed intuitively rather than analytically. These scenario simulations are used to analyze how specific water-management practices affect factors such as water levels, flows, and salinities. In lieu of testing...
Distinguishing black carbon from biogenic humic substances in soil clay fractions
D.A. Laird, M.A. Chappell, D.A. Martens, R.L. Wershaw, M. Thompson
2008, Geoderma (143) 115-122
Most models of soil humic substances include a substantial component of aromatic C either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. We physically separated coarse (0.2–2.0 μm e.s.d.), medium (0.02–0.2 μm e.s.d.), and fine (> 0.02 μm e.s.d.)...
Factors controlling nitrogen release from two forested catchments with contrasting hydrochemical responses
S.F. Christopher, M.J. Mitchell, Michael McHale, E.W. Boyer, Douglas A. Burns, C. Kendall
2008, Hydrological Processes (22) 46-62
Quantifying biogeochemical cycles of nitrogen (N) and the associated fluxes to surface waters remains challenging, given the need to deal with spatial and temporal variability and to characterize complex and heterogeneous landscapes. We focused our study on catchments S14 and S15 located in the Adirondack Mountains...
A comparative analysis of simulated and observed landslide locations triggered by Hurricane Camille in Nelson County, Virginia
M.M. Morrissey, G. F. Wieczorek, B. A. Morgan
2008, Hydrological Processes (22) 524-531
In 1969, Nelson County, Virginia received up to 71 cm of rain within 12 h starting at 7 p.m. on August 19. The total rainfall from the storm exceeded the 1000-year return period in the region. Several thousands of landslides were induced by rainfall associated with Hurricane Camille causing fatalities...
A biodynamic understanding of dietborne metal uptake by a freshwater invertebrate
M.-N. Croteau, S. N. Luoma
2008, Environmental Science & Technology (42) 1801-1806
Aquatic organisms accumulate metals from dissolved and particulate phases. Dietborne metal uptake likely prevails in nature, but the physiological processes governing metal bioaccumulation from diet are not fully understood. We characterize dietborne copper, cadmium, and nickel uptake by a freshwater gastropod (Lymnaea stagnalis) both in terms of biodynamics and membrane...
Removal of dissolved organic matter by anion exchange: Effect of dissolved organic matter properties
T.H. Boyer, P.C. Singer, G. R. Aiken
2008, Environmental Science & Technology (42) 7431-7437
Ten isolates of aquatic dissolved organic matter (DOM) were evaluated to determine the effect that chemical properties of the DOM, such as charge density, aromaticity, and molecular weight, have on DOM removal by anion exchange. The DOM isolates were characterized as terrestrial, microbial, or intermediate humic substances...
Tile drainage as karst: Conduit flow and diffuse flow in a tile-drained watershed
K. E. Schilling, M. Helmers
2008, Journal of Hydrology (349) 291-301
The similarity of tiled-drained watersheds to karst drainage basins can be used to improve understanding of watershed-scale nutrient losses from subsurface tile drainage networks. In this study, short-term variations in discharge and chemistry were examined from a tile outlet collecting subsurface tile flow from a 963 ha agricultural watershed. Study...
Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes
L.G. Miller, R.S. Oremland
2008, Extremophiles (12) 837-848
Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate...
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...
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...
Chemical contaminants, health indicators, and reproductive biomarker responses in fish from rivers in the Southeastern United States
J.E. Hinck, V. S. Blazer, N. D. Denslow, K. R. Echols, R.W. Gale, C. Wieser, T.W. May, M. Ellersieck, J.J. Coyle, D. E. Tillitt
2008, Science of the Total Environment (390) 538-557
Largemouth bass (Micropterus salmoides) and common carp (Cyprinus carpio) were collected from 13 sites located in the Mobile (MRB), Apalachicola–Flint–Chattahoochee (ARB), Savannah (SRB), and Pee Dee (PRB) River Basins to document spatial trends in accumulative chemical contaminants, health indicators, and reproductive biomarkers. Organochlorine residues,...
Decomposition of soil organic matter from boreal black spruce forest: Environmental and chemical controls
K.P. Wickland, J. C. Neff
2008, Biogeochemistry (87) 29-47
Black spruce forests are a dominant covertype in the boreal forest region, and they inhabit landscapes that span a wide range of hydrologic and thermal conditions. These forests often have large stores of soil organic carbon. Recent increases in temperature at northern latitudes may be stimulating decomposition rates of...
Mercury and organic carbon dynamics during runoff episodes from a northeastern USA watershed
P. F. Schuster, J. B. Shanley, M. Marvin-DiPasquale, M.M. Reddy, G. R. Aiken, D.A. Roth, Howard E. Taylor, D. P. Krabbenhoft, J.F. DeWild
2008, Water, Air, & Soil Pollution (187) 89-108
Mercury and organic carbon concentrations vary dynamically in streamwater at the Sleepers River Research Watershed in Vermont, USA. Total mercury (THg) concentrations ranged from 0.53 to 93.8 ng/L during a 3-year period of study. The highest mercury (Hg) concentrations occurred slightly before peak flows and were associated with the highest...
Mid-infrared diffuse reflectance spectroscopic examination of charred pine wood, bark, cellulose, and lignin: Implications for the quantitative determination of charcoal in soils
J. B. Reeves III, G.W. McCarty, D.W. Rutherford, R.L. Wershaw
2008, Applied Spectroscopy (62) 182-189
Fires in terrestrial ecosystems produce large amounts of charcoal that persist in the environment and represent a substantial pool of sequestered carbon in soil. The objective of this research was to investigate the effect of charring on mid-infrared spectra of materials likely to be present in forest...
Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 3. Use of microspheres to estimate the transport potential of Cryptosporidium parvum oocysts
Ronald W. Harvey, David W. Metge, Allen M. Shapiro, Robert A. Renken, Christina L. Osborn, Joseph N. Ryan, Kevin J. Cunningham, Lee L. Landkamer
2008, Water Resources Research (44)
The vulnerability of a municipal well in the Northwest well field in southeastern Florida to potential contamination by Cryptosporidium parvum oocysts was assessed in a large‐scale, forced‐gradient (convergent) injection and recovery test. The field study involved a simultaneous pulse introduction of a nonreactive tracer (SF6, an inert gas) and oocyst‐sized (1.6, 2.9,...
Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir
A.R. Stewart, M. K. Saiki, J.S. Kuwabara, Charles N. Alpers, M. Marvin-DiPasquale, D. P. Krabbenhoft
2008, Canadian Journal of Fisheries and Aquatic Sciences (65) 2351-2366
Physical and biogeochemical characteristics of the aquatic environment that affect growth dynamics of phytoplankton and the zooplankton communities that depend on them may also affect uptake of methylmercury (MeHg) into the pelagic food web of oligotrophic reservoirs. We evaluated changes in the quality and quantity of suspended particulate material, zooplankton...
Biomarkers of mercury exposure at a mercury recycling facility in Ukraine
H.J. Gibb, K. Kozlov, J.P. Buckley, J. Centeno, V. Jurgenson, A. Kolker, K. Conko, E. Landa, B. Panov, Y. Panov, H. Xu
2008, Journal of Occupational and Environmental Hygiene (5) 483-489
This study evaluates biomarkers of occupational mercury exposure among workers at a mercury recycling operation in Gorlovka, Ukraine. The 29 study participants were divided into three occupational categories for analysis: (1) those who worked in the mercury recycling operation (Group A, n = 8), (2) those...
Effects of ionic strength, temperature, and pH on degradation of selected antibiotics
K.A. Loftin, C.D. Adams, M. T. Meyer, R. Surampalli
2008, Journal of Environmental Quality (37) 378-386
Aqueous degradation rates, which include hydrolysis and epimerization, for chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TET), lincomycin (LNC), sulfachlorpyridazine (SCP), sulfadimethoxine (SDM), sulfathiazole (STZ), trimethoprim (TRM), and tylosin A (TYL) were studied as a function of ionic strength (0.0015, 0.050, or 0.084 mg/L as Na2HPO4), temperature (7, 22, and 35°C), and...
Permeability of continental crust influenced by internal and external forcing
S.A. Rojstaczer, S. E. Ingebritsen, D.O. Hayba
2008, Geofluids (8) 128-139
The permeability of continental crust is so highly variable that it is often considered to defy systematic characterization. However, despite this variability, some order has been gleaned from globally compiled data. What accounts for the apparent coherence of mean permeability in the continental crust (and permeability–depth relations) on a very...
Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow
Robert A. Renken, Kevin J. Cunningham, Allen M. Shapiro, Ronald W. Harvey, Michael R. Zygnerski, David W. Metge, Michael A. Wacker
2008, Water Resources Research (44)
The Biscayne aquifer is a highly transmissive karst limestone that serves as the sole source of drinking water to over two million residents in south Florida. The aquifer is characterized by eogenetic karst, where the most transmissive void space can be an interconnected, touching‐vug, biogenically influenced porosity of biogenic origin....
Passive microwave (SSM/I) satellite predictions of valley glacier hydrology, Matanuska Glacier, Alaska
S.E. Kopczynski, J. Ramage, D. Lawson, S. Goetz, E. Evenson, J. Denner, G. Larson
2008, Geophysical Research Letters (35)
We advance an approach to use satellite passive microwave observations to track valley glacier snowmelt and predict timing of spring snowmelt-induced floods at the terminus. Using 37 V GHz brightness temperatures (Tb) from the Special Sensor Microwave hnager (SSM/I), we monitor snowmelt onset when both Tb and the difference between...
Evaporite-karst problems and studies in the USA
K.S. Johnson
2008, Conference Paper, Environmental Geology
Evaporites, including rock salt (halite) and gypsum (or anhydrite), are the most soluble among common rocks; they dissolve readily to form the same types of karst features that commonly are found in limestones and dolomites. Evaporites are present in 32 of the 48 contiguous states in USA, and they underlie...
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...
Susceptibility to enhanced chemical migration from depression-focused preferential flow, High Plains aquifer
Jason J. Gurdak, Michelle Ann Walvoord, Peter B. McMahon
2008, Vadose Zone Journal (7) 1172-1184
Aquifer susceptibility to contamination is controlled in part by the inherent hydrogeologic properties of the vadose zone, which includes preferential-flow pathways. The purpose of this study was to investigate the importance of seasonal ponding near leaky irrigation wells as a mechanism for depression-focused preferential flow and enhanced chemical migration through...
