Research on the application of soluble, metal chelates for water tracing using thermal neutron activation analysis for tracer determination has led to the development of several tracers with promising solution stabilities (conservative behavior) and determination sensitivities. The solution stabilities of the ethylenediamine tetraacetic acid (EDTA) and the diethylenetriamine pentaacetic acid (DTPA) chelates of the activable elements Cr, Co, Eu, In, Sb, Sc and Tb were evaluated in a series of laboratory, radiotracer experiments conducted under simulated field conditions. They showed that 1) chelation of metals produces highly conservative solution behavior, 2) DTPA is generally better than EDTA for improving tracer behavior, 3) non-chelated metals are rapidly sorbed onto sediments and 4) chelation reduces sorption of metals onto sediments. Field tests of EuDTPA, TbDTPA, InDTPA and Rhodamine B fluorescent dye in a small eastern Washington stream demonstrated that the metal chelates have significantly improved solution stabilities in natural water compared to widely used Rhodamine B. Minimum detection levels in natural waters for the activable tracers were determined to be 0.075 ppb for Eu, 0.10 ppb for Tb and 0.55 ppb for In in comparison to 0.49 ppb for Rhodamine B. Associated determination uncertainties (one standard deviation) amount to ±12% for Eu at 12 ppb, ±12% for Tb at 13 ppb, and ±13% for In at 10 ppb compared to ±7.3% for Rhodamine B at 1-10 ppb. Activation procedures are feasible which decrease the minimum detection levels to 0.0015 ppb for Eu, 0.0019 ppb for Tb and 0.0057 ppb for In in comparison to 0.075 ppb for Rhodamine B. Anion-exchange proved uniquely suited for recovery and concentration of metal-chelate tracers from natural water and as a low background irradiation and counting matrix. A method evaluation and economic analysis clarify the potential application of activable metal chelates for water tracing. / Graduation date: 1970

No description available.

No description available.

No description available.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1984. / Includes bibliographical references (leaves 72-74).

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1984. / Bibliography: leaves 61-63.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The measurement of lead isotope abundances with a gas source mass spectrometer has been limited to lead ores and minerals. This thesis describes a technique by means of which the sample size necessary for a precise gas source analysis has been decreased by more than two orders of magnitude. In this way, the range of minerals which may be studied by means of a gas source mass spectrometer has been greatly extended. No particular effort has been made to analyze very small samples. The technique which has been developed begins with the evaporation of lead from a mineral to form a mirror. The synthesis of tetramethyllead is completed by the reaction of free methyl radicals with the lead mirror followed by gas chromatographic purification. The free radical method has been applied to the study of lead isotope abundance variations in the mining district of Sudbury, Ontario. A satisfactory chronological history for this region has not been obtained from the many conventional age determinations that exist. The analysis of lead from various sulphides has yielded lead isotope ratios which are linearly related on a plot of Pb²⁰⁷/Pb²⁰⁴ vs. Pb²⁰⁶/Pb²⁰⁴ with a slope of 0.131 ± 0.003. The standard deviation of points from their best straight line is 0.37% of the average Pb²⁰⁷/Pb²⁰⁴ value. From these results it is concluded that the linear relationship is the result of just two geological events, which fact simplifies the possible interpretations. The maximum ages for these two events are 2150 ± 50 million years and 1280 ± 50 million years. Two interpretations of the results are suggested. The first gives ages of 1950 million years and 350 million years for the primary and secondary events. The two events in the second interpretation are considered to have occurred 1600 million years and 950 million years ago. The second interpretation is more easily defended on geological grounds. The simple relationship of lead isotope ratios which has been observed in the Sudbury district is particularly significant in view of the geological complexity of this region. Thus the technique developed may be expected to have wide application. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The use of trichlorofluoromethane (C1₃CF) as a refrigerant, aerosol-can propellant, and foam-blowing agent leads to the subsequent release of C1₃CF into the atmosphere. During the mid-1970's, the build-up of C1₃CF in the stratosphere resulted in much atmospheric research investigating the destruction of the earth's ozone layer by C1₃CF. C1₃CF enters the hydrologic cycle during precipitation. Hydrologic investigations led to the detection of C1₃CF in ground water and postulation of C1₃CF as a tracer and age dating technique. The Edwards Aquifer in the vicinity of San Antonio, Texas, was chosen as a test case for demonstration of C1₃CF as an environmental tracer. The aquifer has been modeled for mass transport using extensive tritium measurements to calibrate and verify a discrete-state model (DSM). The DSM was the first successful attempt at modeling both flow and mass transport in that aquifer. Without changing the calibration, the DSM was used to model the input-output and predict the concentration of C1₃CF in the aquifer. Field sampling of surface water, well discharge, springs, and the atmosphere was done in 1977 in order to compare actual with predicted results. C1₃CF was measured using a custom field operable gas chromatograph (FOGC). The FOGC has a solute-stripping bottle, a backflushing column, a pulsed electron capture detector, and an automatic peak-window integrator. The theoretical detection limit is 10⁻⁴ grams per second. The FOGC was calibrated for a dynamic range of 0.25 to 300 picograms, using a permeation tube and dynamic gas sampler. The FOGC can measure C1₃CF in ground waterat concentrations of 0.01 picograms per milliliter (pg/ml) within 2 percent. Analysis and interpretation of the ground-water data indicated two distinct associations -- regional data points and plume data points. The regional data points fell into two separate groups, those above and those below the lower calibration limit. The data points were high in the recharge areas, intermediate in the center of the aquifer, lower at the discharge points (springs), and below the calibration limit in areas of low circulation in the aquifer. Comparison of the regional data with other investigations indicates that the C1₃CF technique works. The data points in the plume area indicate artificial introduction of C1₃CF into the aquifer near San Antonio. The distribution of the concentrations follows the flow paths toward the springs and confirms the movement of ground water as determined from previous investigations utilizing other techniques. The artificial introduction of C1₃CF may have been accidental or intentional. It appears that about 15 liters C1₃CF would be required to produce the concentrations detected. Air sample concentrations of C1₃CF (0.42 pg/ml) were about half those reported for recent global measurements. Surface water concentrations of C1₃CF (0.12 pg/ml) were very close to recent global measurements (0.13 pg/ml), but below the input to the model (0.34 pg/ml). The data indicate that the C1₃CF technique is workable in the Edwards Aquifer and should be in other systems containing water recharged during the last 30 years. The consistency of the data indicates that the technique probably is more usable than tritium because of the much simpler input function. The FOGC is appealing because of its portability, low cost, and ease of operation.

Thesis--Universiteit van Utrecht. / Bibliography: p. 101-104.