Characterization of Contaminant Transport Using Naturally-Occurring U-Series Disequilibria

Study the migration of nuclear waste contaminants in subsurface fractured systems using naturally occurring uranium and thorium-series radionuclides as tracers under in-situ physico-chemical and hydrogeologic conditions. Radioactive disequilibria among members of these decay-series nuclides can provide information on the rates of adsorption-desorption and transport of contaminants as well as on fluid transport and rock dissolution in a natural setting

Decadal hydroclimatic variability in the western coastal United States: temporal and spatial variations in precipitation, streamflow, and lake level

EXTRACT (SEE PDF FOR FULL ABSTRACT): We have analyzed streamflow variations recorded at 15 USGS gauging stations in California during the past 90 years or so. The anomalies (departures from the 1960-1990 mean discharge) of streamflow on annual-to-decadal time scales are strongly correlated with precipitation anomalies in each drainage basin. ... Although causes of the decadal climate (precipitation) variability are not known with certainty, the use of streamflow records may help us understand the relative strengths of moisture sources and shift of the jet stream in atmospheric circulation

An evaluation of the U234/U238 method as a tool for dating pelagic sediments

The possibility of using the 15% excess U234 activity in oceanic uranium for dating pelagic sediments in the age range 100,000 years to more than 1 m.y. has been explored. Results from a series of analyses of bulk samples, mechanical separates, and acid leach fractions indicate that separation of authigenic uranium from detrital uranium by either mechanical or chemical means is impractical. Measurements on totally dissolved samples reveal that the sediments do not form a closed system; post-depositional migration of U234 in the sedimentary column takes place. Based on the experimental data obtained from three red-clay cores with sedimentation rates ranging from 2 to 6 mm/1000 yr, a model depicting diffusion of the U234 generated within the sediments is proposed. The diffusion equation includes three parameters: sedimentation rate, diffusion coefficient for U234, and fraction of the internally produced U234 subject to mobility. If the amount of U234 lost from these cores is typical, a sizeable part of the U234 excess in the sea must be from this source

Characterization of Contaminant Transport Using Naturally Occurring U-Series Disequilibria

The main goal of the research is to understand the migratory behavior of radioactive contaminants in subsurface fractured systems by using naturally occurring U-series radionuclides as tracers under in-situ physico-chemical and hydrogeologic conditions. Naturally-occurring uranium- and thorium-series radioactive disequilibria can provide information on the rates of adsorption-desorption and transport of radioactive contaminants as well as on fluid transport and rock dissolution in a natural setting. This study will also provide an improved understanding of the hydrogeologic features of the site and their impact on the migration of radioactive contaminants. We intend to produce a realistic model of radionuclide migration in the Snake River Plain Aquifer beneath the INEEL by evaluating the retardation processes involved in the rock/water interaction. The major tasks are to (1) determine the natural distribution of U, Th, Pa and Ra isotopes in the groundwater as well as in rock minerals and sorbed phases, and (2) study rock/water interaction processes using U/Th series disequilibrium and a statistical analysis based model code for the calculation of in-situ retardation factors of radionuclides and rock/water interaction time scales