Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
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Simulation of solute transport in a mountain pool-and-riffle stream: A transient storage model
The physical characteristics of mountain streams differ from the uniform and conceptually well- defined open channels for which the analysis of solute transport has been oriented in the past and is now well understood. These physical conditions significantly influence solute transport behavior, as demonstrated by a transient storage model simulation of solute transport in a very small (0.0125 m3s−
Authors
Kenneth E. Bencala, Roy A. Walters
Requirements for modeling trace metal partitioning in oxidized estuarine sediments
The fate of particulate-bound metals is of particular importance in estuaries because major biological energy flows involve consumption of detrital particles. The biological impact of particulate-bound metals is strongly influenced by the partitioning of metals among sediment components at the oxidized sediment-water interface. Adequate methods for directly measuring this partitioning are not avai
Authors
Samuel N. Luoma, J.A. Davis
Variable tolerance to copper in two species from San Francisco Bay
In static toxicity experiments, tolerance to soluble Cu of the bivalve, Macoma balthica, and the copepod, Acartia clausi, varied substantially among populations sampled within San Francisco Bay. Intraspecific tolerance differed ten-fold or more for both species over relatively small distances, suggesting geographical isolation of populations is not a prerequisite for the development of intraspecif
Authors
Samuel N. Luoma, D.J. Cain, K. Ho, A. Hutchinson
Nonequilibrium models for predicting forms of precipitated manganese oxides
Manganese oxides precipitated by bubbling air through 0.01 molar solutions of MnCl2, Mn(NO3)2, MnSO4, or Mn(ClO4)2 at a constantly maintained pH of 8.5 to 9.5 at temperatures of 25°C or higher consisted mainly of hausmannite, Mn3O4. At temperatures near 0°C, but with other conditions the same, the product is feitknechtite, βMnOOH, except that if the initial solution is MnSO4 and the temperature is
Authors
J. D. Hem, Carol J. Lind
Gas-film coefficients for streams
Equations for predicting the gas-film coefficient for the volatilization of organic solutes from streams are developed. The film coefficient is a function of windspeed and water temperature. The dependence of the coefficient on windspeed is determined from published information on the evaporation of water from a canal. The dependence of the coefficient on temperature is determined from laboratory
Authors
R. E. Rathbun, D. Y. Tai
Simulation of solute transport in a mountain pool-and-riffle stream with a kinetic mass transfer model for sorption
In natural channels there are often long periods of low flow during which solutes have repeated opportunity for contact with relatively immobile bed materials. Such conditions can exist in very small pool-and-riffle mountain streams. If a solute can sorb onto bed materials, then both hydrodynamic and chemical processes control solute transport. A simulation of these processes is presented for a ca
Authors
Kenneth E. Bencala
Kinetic analysis of strontium and potassium sorption onto sands and gravels in a natural channel
A kinetic, first-order mass transfer model was used to describe the sorption of strontium onto sand- and gravel-sized streambed sediments. Rate parameters, empirically determined for strontium, allowed for the prediction of potassium sorption with moderate success. The model parameters varied significantly with particle size. The sorption data were collected during an experimental injection of sev
Authors
Kenneth E. Bencala, Alan P. Jackman, Vance C. Kennedy, Ronald J. Avanzino, Gary W. Zellweger
Clay mineral formation and transformation in rocks and soils
Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for the origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a
Authors
D. D. Eberl
Ultrastructural changes in the hepatocytes of juvenile rainbow trout and mature brown trout exposed to copper or zinc
Morphological changes in hepatocytes of mature brown trout (Salmo trutta Linnaeus) and juvenile rainbow trout (Salmo gairdneri Richardson), accompanying chronic exposures to copper and zinc, were examined by transmission electron microscopy. At a concentration of copper not inhibitory to the final stages of gonadal development or spawning of brown trout, structural alterations included contraction
Authors
H.V. Leland
A reexamination of the effects of adsorbates on the Raman spectrum of gibbsite
Previous workers have attributed substantial changes in the Raman intensities of the OH stretching bands in solid, powdered gibbsite of surface area 10 m2/g to surface interactions with the adsorbates 093Ca2+,HxPO43x- and SiO2.xH2O. These changes apparently resulted from an unsatisfactory Raman measurement procedure as a re-examination using an internal intensity standard (Na2C2O4 crystals) with g
Authors
K.W. Cunningham, M. C. Goldberg
Bioavailability of trace metals to aquatic organisms — A review
No abstract available.
Authors
Samuel N. Luoma
Complexation of copper by aquatic humic substances from different environments
The copper-complexing properties of aquatic humic substances isolated from eighteen different environments were characterized by potentiometric titration, using a cupric ion selective electrode. Potentiometric data were analyzed using FITEQL, a computer program for the determination of chemical equilibrium constants from experimental data. All the aquatic humic substances could be modelled as havi
Authors
Diane M. McKnight, Gerald L. Feder, E. Michael Thurman, Robert L. Wershaw