Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
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Effects of small-scale vertical variations in well-screen inflow rates and concentrations of organic compounds on the collection of representative ground-water-quality samples
Because a water sample collected from a well is an integration of water from different depths along the well screen, measured concentrations can be biased if analyte concentrations are not uniform along the length of the well screen. The resulting concentration in the sample, therefore, is a function of variations in well-screen inflow rate and analyte concentration with depth. A multiport sampler
Authors
Jacob Gibs, G. Allan Brown, Kenneth S. Turner, Cecilia L. MacLeod, James Jelinski, Susan A. Koehnlein
Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate
EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages. Spectra also were collected for arsenate adsorbed on the surfaces of three FeOOH crystalline polymorphs, α (goethite), β (akaganeite), and γ (lepidocrocite), and as a free ion in aq
Authors
G.A. Waychunas, B.A. Rea, C. C. Fuller, J.A. Davis
A finite-volume Eulerian-Lagrangian Localized Adjoint Method for solution of the advection-dispersion equation
A new mass-conservative method for solution of the one-dimensional advection-dispersion equation is derived and discussed. Test results demonstrate that the finite-volume Eulerian-Lagrangian localized adjoint method (FVELLAM) outperforms standard finite-difference methods, in terms of accuracy and efficiency, for solute transport problems that are dominated by advection. For dispersion-dominated p
Authors
R. W. Healy, T.F. Russell
Effect of treated-sewage contamination upon bacterial energy charge, adenine nucleotides, and DNA content in a sandy aquifer on Cape Cod
Changes in adenylate energy charge (ECA) and in total adenine nucleotides (AT) and DNA content (both normalized to the abundance of free-living, groundwater bacteria) in response to carbon loading were determined for a laboratory-grown culture and for a contaminated aquifer. The latter study involved a 3-km-long transect through a contaminant plume resulting from continued on-land discharge of sec
Authors
David W. Metge, Myron H. Brooks, Richard L. Smith, Ronald W. Harvey
The role of water exchange between a stream channel and its hyporheic zone in nitrogen cycling at the terrestrial-aquatic interface
The subsurface riparian zone was examined as an ecotone with two interfaces. Inland is a terrestrial boundary, where transport of water and dissolved solutes is toward the channel and controlled by watershed hydrology. Streamside is an aquatic boundary, where exchange of surface water and dissolved solutes is bi-directional and flux is strongly influenced by channel hydraulics. Streamside, bi-dire
Authors
F.J. Triska, J.H. Duff, R. J. Avanzino
Concentration history during pumping from a leaky aquifer with stratified initial concentration
Analytical and numerical solutions are employed to examine the concentration history of a dissolved substance in water pumped from a leaky aquifer. Many aquifer systems are characterized by stratification, for example, a sandy layer overlain by a clay layer. To obtain information about separate hydrogeologic units, aquifer pumping tests are often conducted with a well penetrating only one of the l
Authors
Daniel J. Goode, Paul A. Hsieh, Allen M. Shapiro, Warren W. Wood, Thomas F. Kraemer
Application of mixed-mode, solid-phase extraction in environmental and clinical chemistry. Combining hydrogen-bonding, cation-exchange and Van der Waals interactions
Silica- and styrene-divinylbenzene-based mixed-mode resins that contain C8, C18 and sulphonated cation-exchange groups were compared for their efficiency in isolation of neutral triazine compounds from water and of the basic drug, benzoylecgonine, from urine. The triazine compounds were isolated by a combination of Van der Waals and hydrogen-bonding interactions, and benzoylecgonine was isolated b
Authors
M. S. Mills, E. M. Thurman, M.J. Pedersen
Development of a model of phytoplankton blooms in Manukau Harbour
No abstract available.
Authors
Graham B. McBride, W. N. Vant, J. E. Cloern, J. B. Liley
Seasonal relationships between planktonic microorganisms and dissolved organic material in an alpine stream
The relationships between the abundance and activity of planktonic, heterotrophic microorganisms and the quantity and characteristics of dissolved organic carbon (DOC) in a Rocky Mountain stream were evaluated. Peak values of glucose uptake, 2.1 nmol L−1 hr−1, and glucose concentration, 333 nM, occurred during spring snowmelt when the water temperature was 4.0°C and the DOC concentration was great
Authors
Diane M. McKnight, R. L. Smith, R.A. Harnish, C.L. Miller, K.E. Bencala
Manganese minerals and associated fine particulates in the streambed of Pinal Creek, Arizona, U.S.A.: a mining-related acid drainage problem
The Pinal creek drainage basin in Arizona is a good example of the principal non-coal source of mining-related acid drainage in the U.S.A., namely copper mining. Infiltration of drainage waters from mining and ore refining has created an acid groundwater plume that has reacted with calcite during passage through the alluvium, thereby becoming less acid. Where O2 is present and the water is partial
Authors
Carol J. Lind, J. D. Hem
Tidal, Residual, Intertidal Mudflat (TRIM) Model and its Applications to San Francisco Bay, California
A numerical model using a semi-implicit finite-difference method for solving the two-dimensional shallow-water equations is presented. The gradient of the water surface elevation in the momentum equations and the velocity divergence in the continuity equation are finite-differenced implicitly, the remaining terms are finite-differenced explicitly. The convective terms are treated using an Eulerian
Authors
R. T. Cheng, V. Casulli, J. W. Gartner
New reference materials for nitrogen-isotope-ratio measurements
Three new reference materials were manufactured for calibration of relative stable nitrogen‐isotope‐ratio measurements:USGS25 (ammonium sulfate) δ615″=−30 per milUSGS26 (ammonium sulfate) δ615″=+54 per milUSGS32 (potassium nitrate) δ615″=+180 per milwhere δN′, relative to atmospheric nitrogen, is an approximate value subject to change following interlaboratory comparisons. These materials are isot
Authors
John K. Böhlke, C. J. Gwinn, T. B. Coplen