This thesis reports two new methods developed to study the free ion activity of aluminum and copper. Both methods could be applied to the study of other metals. The first method measures the apparent solubility of aluminum and sulfate in a dynamic, leached system. This system is believed to give a good representation of the field situation where soils are continuously leached and never at equilibrium. This study was done under three sulfate concentrations. The part of the experiment using low sulfate concentrations showed aluminum solubility control by a gibbsite-like solid phase with a log K$ sp circ$ of 7.49. It was also shown, however, that under natural soil solution concentrations of sulfate in acidic forest soils, an interaction with sulfate controls aluminum activity rather than gibbsite solubility equilibria. This interaction is either, an aluminum-sulfate solid phase or, a stoichiometric ion-pair co-adsorption of aluminum and sulfate. / The second method is a simple determination of free Cu$ sp{2+}$ in soils using a cupric ion-selective electrode. Free copper has been demonstrated to be the toxicity controlling component in aquatic studies and this study was undertaken to measure free copper activity in soils. The possible interference due to ionic strength variations or the presence of aluminum in the soil solution was checked and found to be negligible. The free activity of copper (pCu$ sp{2+}$) measured in a variety of pristine and contaminated soils varied between 6.33 to 12.20 pCu$ sp{2+}$ units. Total soil copper content and acidity were shown to strongly increase copper solubility and free Cu$ sp{2+}$ activity in the soil solution extracts. (Abstract shortened by UMI.)

Radon transport mechanisms in soils were studied to determine the dominant transport mechanism for Delaware county soils. In modeling the soil, it was assumed that is was homogenous and moisture-free. Two transport mechanisms were investigated, the transport of radon in the soil by molecular diffusion (assumed to be governed by Fick's law) and transport by pressure-induced flow or convection (assumed to be governed by Darcy's law). Following the previous work of W. E. Clements, a general transport equation was described which incorporated both diffusion and convection. In steady-state conditions, a closed-form solution was obtained for the concentration of radon in the soil interstices as a function of depth. Similarly, solutions were examined for transport by diffusion alone. Representative soil parameters were assigned and the diffusion fraction (the ratio of concentration due to diffusion to the concentration due to both diffusion and convection) was calculated. Referring to the work of A. B. Tanner, a radon availability number (RAN) was determined for the soils; the RAN value was a measure of the activity of radon per unit area. Analyses were also performed to determine the significance of pressure variations on calculated diffusion fractions and RAN values. For 99% of the acreage in Delaware county, the diffusion fraction was 0.95 or greater. Therefore, it was concluded that molecular diffusion is the dominant transport mechanism for the soils of Delaware county. / Department of Physics and Astronomy

Although the soil solution lies at the centre of many of the processes which occur in soils, little information is available on the chemical composition of the soil solutions of field soils, or on the temporal and spatial variability of such solutions. The suitability of an immiscible fluid centrifugation method for obtaining samples of the soil solution was evaluated. The method was found to be substantially free from interferences and well suited to routine use. It was adapted for use with soils of low bulk density. Yields of soil solution from soils at or near field capacity ranged from 20 to 50% of the total water present. However little or no soil solution could be extracted from dry soils. Displaced solutions were analysed for about 20 solutes principally by inductively coupled plasma spectroscopy. Typical solute concentrations in soil solutons from six neutral and calcareous soil series in the Oxford area were in the range 10^-2.4 to 10^-3.4 M for Na, K, Ca, S, Cl, N0₃, alkalinity and dissolved organic carbon (DOC); 10^-3.4 to 10^-4.4 M for Mg, Si and P and <10^-5.33 M for B, Li r Y, Ba, Mn, Cu, Fe, V, Zn, Al, Pb f Ni, Cd, Co, Sr and Mo. Short-range (5-10 m) variability was significantly less, and between-soil series variability significantly more, than the variability found between grass fields on the same soil series for most solutes. The main exception to this was N0₃ which exhibited a large between-field variability. In general, soil solutions from arable soils were more dilute than those from nearby pasture soils. Solutions from poorly drained sites on a heavy clay soil were more concentrated than those from freely draining sites on the same soil series. A year-long sampling programme showed that with the exception of P and alkalinity the concentrations of solutes in the soil solution changed significantly with time. The temporal range in the concentrations of solutes was found to increase in the order Si-Pandlt;alkalinity-Feandlt;Naandlt;Ca-Sr-Mg-Cuandlt;S-DOCandlt;K-Znandlt;Cl-pHandlt;Mn.

In this research project, systematic studies of polymer-assisted flocculation and dewatering behaviour of colloidal gibbsite (y-Al(OH)3) dispersions, together with polymeric flocculant structure-mediated interfacial chemistry and particle interactions, have been performed. Clear links between flocculation performance, interfacial chemistry, particle interactions, dispersion settling rate and sediment consolidation were established for improved dewaterability.

Copies of author's previously published works inserted. / Bibliography: leaves 260-299. / xxii, 299 leaves, [7] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis describes the concept of organic matter turnover and various methods to measure the decay rates of organic materials in the soil. Methods are developed to separate SOM from different locations within the soil matrix. Free particulate organic matter (POM), located between or outside the soil aggregates is isolated. Occluded POM is disaggregeted by sonification. The compositional differences noted among the three components of SOM are used to describe the changes that OM undergoes during decomposition. The process is followed as organic matter enters the soil, is enveloped in aggregates and is eventually incorporated into the microbial biomass and metabolites then becoming associated with clay minerals. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1997

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains ix, 128 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (Ph.D.)--Tufts University, 2005. / Adviser: Samuel P. Kounaves. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph. D.?)--Universitat Bayreuth, 2006.

Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed June 17, 2009). Vita. Includes bibliographical references.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 26, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Robert J. Kremer. Vita. Includes bibliographical references.