Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
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Evaluation of hydraulic conductivities calculated from multi-port permeameter measurements
A multiport permeameter was developed for use in estimating hydraulic conductivity over intact sections of aquifer core using the core liner as the permeameter body. Six cores obtained from one borehole through the upper 9 m of a stratified glacial-outwash aquifer were used to evaluate the reliability of the permeameter. Radiographs of the cores were used to assess core integrity and to locate 5-
Authors
Steven H. Wolf, Michael A. Celia, Kathryn M. Hess
Quartz dissolution in organic-rich aqueous systems
Organic electrolytes are a common component of natural waters and are known to be important in many rock-water interactions. The influence of organic electrolytes on silica mobility, quartz solubility, and quartz dissolution kinetics, however, is less well understood. While there is mounting evidence supporting the presence of an aqueous organic-silica complex in natural waters, the significance o
Authors
Philip C. Bennett
Agricultural research to improve water quality
ime courses for ingest~on, retention and release via feces of microbial food was investigatedusing 2 b~valves w~th d~fferent feeding strategies, Potamocorbula amurensis and Macomabalthica. The results showed 2 pathways for the uptake of food material in these clams. The first isrepresented by an initlal label pulse in the feces. The second pathway operates over longer timeperiods. Inert "Cr-labele
Authors
C.A. Onstad, M. R. Burkart, G.D. Bubenzer
Centrifugal techniques for measuring saturated hydraulic conductivity
Centrifugal force is an alternative to large pressure gradients for the measurement of low values of saturated hydraulic conductivity (Ksat). With a head of water above a porous medium in a centrifuge bucket, both constant-head and falling-head measurements are practical at forces up to at least 1800 times normal gravity. Darcy's law applied to the known centrifugal potential leads to simple formu
Authors
John R. Nimmo, Karen A. Mello
Extent of reaction in open systems with multiple heterogeneous reactions
The familiar batch concept of extent of reaction is reexamined for systems of reactions occurring in open systems. Because species concentrations change as a result of transport processes as well as reactions in open systems, the extent of reaction has been less useful in practice in these applications. It is shown that by defining the extent of the equivalent batch reaction and a second contribut
Authors
John C. Friedly
Large-scale natural gradient tracer test in sand and gravel, Cape Cod, Massachusetts: 1. Experimental design and observed tracer movement
A large-scale natural gradient tracer experiment was conducted on Cape Cod, Massachusetts, to examine the transport and dispersion of solutes in a sand and gravel aquifer. The nonreactive tracer, bromide, and the reactive tracers, lithium and molybdate, were injected as a pulse in July 1985 and monitored in three dimensions as they moved as far as 280 m down-gradient through an array of multilevel
Authors
Denis R. LeBlanc, Stephen P. Garabedian, Kathryn M. Hess, Lynn W. Gelhar, Richard D. Quadri, Kenneth G. Stollenwerk, Warren W. Wood
Sampling design for groundwater solute transport: Tests of methods and analysis of Cape Cod tracer test data
Tests of a one-dimensional sampling design methodology on measurements of bromide concentration collected during the natural gradient tracer test conducted by the U.S. Geological Survey on Cape Cod, Massachusetts, demonstrate its efficacy for field studies of solute transport in groundwater and the utility of one-dimensional analysis. The methodology was applied to design of sparse two-dimensional
Authors
Debra S. Knopman, Clifford I. Voss, Stephen P. Garabedian
Neotectonic effects on sinuosity and channel migration, Belle Fourche River, Western South Dakota
Short-term instability in the behaviour of a small, meandering alluvial channel is identified from the relation between sinuosity and either floodplain slope or channel slope within 17 reaches along an 81-kilometre section of the Belle Fourche River in western South Dakota. In reaches 1 to 4 and 11 to 17 the channel is relatively stable and sinuosity varies inversely with channel slope. In reaches
Authors
Basil Gomez, Donna C. Marron
Large-scale natural gradient tracer test in sand and gravel, Cape Cod, Massachusetts: 2. Analysis of spatial moments for a nonreactive tracer
A large-scale natural gradient tracer test was conducted to examine the transport of reactive and nonreactive tracers in a sand and gravel aquifer on Cape Cod, Massachusetts. As part of this test the transport of bromide, a nonreactive tracer, was monitored for about 280 m and quantified using spatial moments. The calculated mass of bromide for each sampling date varied between 85% and 105% of the
Authors
Stephen P. Garabedian, Dennis R. LeBlanc, Lynn W. Gelhar, Michael A. Celia
Comment on the treatment of residual water content in “A consistent set of parametric models for the two-phase flow of immiscible fluids in the subsurface” by L. Luckner et al.
Luckner et al. [1989] (hereinafter LVN) present a clear summary and generalization of popular formulations used for convenient representation of porous media fluid flow characteristics, including water content (θ) related to suction (h) and hydraulic conductivity (K) related to θ or h. One essential but problematic element in the LVN models is the concept of residual water content (θr; in LVN, θw,
Authors
John R. Nimmo
Assessing the solubilities and reaction kinetics of aluminous minerals in soils
The use of chemical thermodynamics and reaction kinetics is necessary to quantitatively model the transformation of aluminous minerals and their dissolved constituents in soils and other geochemical systems. Soils are thermodynamically open systems subject to atmospheric and biological forces and do not attain overall thermodynamic equilibrium with respect to either mass or time. However, local or
Authors
Howard M. May, D. Kirk Nordstrom
Evaluation of unsaturated zone air permeability through pneumatic tests
Predicting the steady state distribution of air pressure in the unsaturated zone resulting from a pneumatic test provides a method for determining air-phase permeability. This technique is analogous to the inverse problem of well hydraulics; however, air flow is more complicated than ground water flow because of air compressibility, the Klinkenberg effect, variations in air density and viscosity t
Authors
Arthur L. Baehr, Marc F. Hult