Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3787
Patterns of hydrological exchange and nutrient transformation in the hyporheic zone of a gravel-bottom stream: examining terrestrial- aquatic linkages
The terrestrial-aquatic interface beneath a riparian corridor was investigated as a region of hydrological and biological control of nutrient flux. Dissolved oxygen (DO) concentration in the hyporheic zone ranged from <1.0 to 9.5 mg l-1 due to permeability variations in bankside sediments. DO concentration was related to the proportion of stream water in the lateral hyporheic zone, indicating that
Authors
F.J. Triska, J.H. Duff, R. J. Avanzino
Surface chemistry of ferrihydrite: Part 2. Kinetics of arsenate adsorption and coprecipitation
The kinetics of As(V) adsorption by ferrihydrite was investigated in coprecipitation and postsynthesis adsorption experiments conducted in the pH range 7.5-9.0. In coprecipitation experiments, As(V) was present in solution during the hydrolysis and precipitation of iron. In adsorption experiments, a period of rapid (<5 min) As(V) uptake from solution was followed by continued uptake for at least e
Authors
C. C. Fuller, J.A. Dadis, G.A. Waychunas
Dissolved inorganic nitrogen composition, transformation, retention, and transport in naturally phosphate-rich and phosphate-poor tropical streams
The composition, transformation, and transport of dissolved inorganic nitrogen (DIN) was compared in waters associated with two lowland streams in Costa Rica. The Salto River is enriched by geothermal-based soluble reactive phosphorus (SRP), which raises the concentration up to 200 μg/L whereas Pantano Creek, an unimpacted tributary, has an SRP concentration <10 μg/L. Ammonium concentration in spr
Authors
F.J. Triska, C. M. Pringle, G. W. Zellweger, J.H. Duff, R. J. Avanzino
Deposition of aerially applied BT in an oak forest and its prediction with the FSCBG model
Data are provided from 17 single-swath aerial spray trials that were conducted over a fully leafed, 16-m tall, mixed oak forest. The distribution of cross-swath spray deposits was sampled at the top of the canopy and below the canopy. Micrometeorological conditions were measured above and within the canopy during the spray trials. The USDA Forest Service FSCBG (Forest Service-Cramer-Barry-Grim) mo
Authors
Dean E. Anderson, David R. Miller, Yansen Wang, William G. Yendol, Karl Mierzejewski, Michael L. McManus
Deep-living microbes mount a relentless attack on rock
No abstract available.
Authors
T. Appenzeller
A geochemical transport model for redox-controlled movement of mineral fronts in groundwater flow systems: A case of nitrate removal by oxidation of pyrite
A one-dimensional prototype geochemical transport model was developed in order to handle simultaneous precipitation-dissolution and oxidation-reduction reactions governed by chemical equilibria. Total aqueous component concentrations are the primary dependent variables, and a sequential iterative approach is used for the calculation. The model was verified by analytical and numerical comparisons a
Authors
Peter Engesgaard, Kenneth L. Kipp
Modeling biotic uptake by periphyton and transient hyporrheic storage of nitrate in a natural stream
To a convection-dispersion hydrologic transport model we coupled a transient storage submodel (Bencala, 1984) and a biotic uptake submodel based on Michaelis-Menten kinetics (Kim et al., 1990). Our purpose was threefold: (1) to simulate nitrate retention in response to change in load in a third-order stream, (2) to differentiate biotic versus hydrologie factors in nitrate retention, and (3) to pro
Authors
Brian K.A. Kim, Alan P. Jackman, Frank J. Triska
Inductively coupled plasma-mass spectrometry as an element-specific detector for field-flow fractionation particle separation
An inductively coupled plasma-mass spectrometer was used for the quantitative measurement of trace elements In specific,submicrometer size-fraction particulates, separated by sedimentation field-flow fractionation. Fractions were collected from the eluent of the field-flow fractionation centrifuge and nebulized, with a Babington-type pneumatic nebulizer, into an argon inductively coupled plasma-ma
Authors
Howard E. Taylor, John R. Garbarino, Deirdre M. Murphy, Ronald Beckett
Use of chlorofluorocarbons (CCl3F and CCl2F2) as hydrologic tracers and age‐dating tools: The alluvium and terrace system of central Oklahoma
The use of Chlorofluorocarbons (CFCs) as an age‐dating tool and tracer in shallow groundwaters has been investigated. New methodology for field sampling and preserving groundwaters containing parts per trillion concentrations of the CFCs, F‐1l and F‐12, is presented. Samples are analyzed by purge‐and‐trap gas chromatography with an electron capture detector. Physical and chemical processes that ca
Authors
Eurybiades Busenberg, Niel Plummer
Relation of nickel concentrations in tree rings to groundwater contamination
Increment cores were collected from trees growing at two sites where groundwater is contaminated by nickel. Proton-induced X ray emission spectroscopy was used to determine the nickel concentrations in selected individual rings and in parts of individual rings. Ring nickel concentrations were interpreted on the basis of recent concentrations of nickel in aquifers, historical information about site
Authors
Thomas M. Yanosky, Don A. Vroblesky
Large-scale natural gradient tracer test in sand and gravel, Cape Cod, Massachusetts: 3. Hydraulic conductivity variability and calculated macrodispersivities
Hydraulic conductivity (K) variability in a sand and gravel aquifer on Cape Cod, Massachusetts, was measured and subsequently used in stochastic transport theories to estimate macrodispersivities. Nearly 1500 K measurements were obtained by borehole flowmeter tests and permeameter analyses of cores. The geometric mean for the flowmeter tests (0.11 cm/s) is similar to that estimated from other fiel
Authors
Kathryn M. Hess, Steven H. Wolf, Michael A. Celia
Discussion of "The modeling process and model validation" by Chin-Fu Tsang
No abstract available.
Authors
Leonard F. Konikow