Thesis (Ph. D.)--University of Wisconsin--Madison, 1951. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 191-205).

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Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 219-237). Available also in a digital version from Dissertation Abstracts.

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The products of pyrite oxidation, including solution phase Fe2+, Fe3+, S2O32-, S4O62-, SO32- and SO42- and solid phase Fe(OH)3, were measured under controlled conditions in order to investigate the behavior of pyrite in calcareous and alkaline soils. The distribution of sulfur oxidation products is pH dependent and can be interpreted in terms of metastable equilibrium among thiosulfate, disulfane disulfonate and sulfite. Thisulfate and sulfite predominate in the pH range greater than about pH 7 or 8. Sulfane disulfonates are more predominant at more acid pH. Solution concentration data were consistent with the presence of Fe(OH)3. Concentrations of thiosulfate and sulfane disulfonate were consistent with a redox equilibrium among solution iron and sulfure species at pH 6 to 9. Linear or zero-order kinetics were found to be sufficient for description of pyrite oxidation in this study. Linear kinetics were observed as electrical conductivity, solution sulfur products and solution plus solid phase iron products. The measurement of solution iron plus solid-phase iron oxide is a more rigorous approach to the extent of reaction than the measurement of sulfate. The rate of pyrite oxidation is pH dependent, increasing from 10-20 pmol(Fe) m-2 s-1 to 40-60 pmol(Fe) m-2 s-1 between pH 5 and 9. This is consistent with an oxidation mechanism involving the reoxidation of solution Fe2+ via a reaction between an iron hydroxide complex and hydrated oxygen as the rate-determining step. The effect o background electrolytes on oxidation rates at low pH also supports this interpretation. Pyrite oxidation rates in the presence of calcium carbonate, sodium bicarbonate, sodium thiosulfate and calcium-saturated bentonite can be related to the pH effect. Sodium thiosulfate and DTPA appeared to have specific inhibitory effects. Column studies show that the disposal of pyritic mine spoils or tailings by mixing with calcareous material may produce thiosulfate, a good reducing agent for toxic metals. Burial of lime below pyritic materials may protect groundwater quality more effectively than application of lime to the surface.

Chemical input-output analyses were used to evaluate the rate of rock weathering and soil development on a granitic inselberg of the Dragoon Mountains in southeastern Arizona. Soil genesis relationships were investigated through field and laboratory study of the soil profile, parent rock, microclimate and vegetation, on different catena positions and hillside aspects. Precipitation and runoff water qualities were determined, with increased summer acidity. Precipitation volume was estimated by extrapolating data from a nearby recording station. Runoff volume was estimated by the U.S.D.A.-S.C.S. Curve Number Method (1972). These data enabled the quantitative determination of cationic solution loss. The indicated decreasing order of cation mobility is calcium, sodium, potassium and magnesium. Cations of higher mobility are relatively depleted in the hillcrest soils, while transported to the footslope or beyond. Calcium, and to a lesser extent sodium, have experienced more extensive off-site removal. Differences resulting from the transformation of parent material to soil were analyzed by field morphology, X-ray analysis, laser light-scattering particle size analysis, and chemical analyses. The study site was surveyed, mapped and the spatial arrangement of soil taxa and their compositional variation were studied. Nearly all pedons on the crest or transport slope are Lithic Ustic Torriorthents; whereas footslope soils show greater development, as exemplified by the occurrence of various Haplargids, Haplustolls and Argiustolls. Weathering rates were calculated using a methodology similar to that of F. W. Barth (1961). Potassium and magnesium provided the most reasonable data of 350 and 430 Kg ha⁻¹ yr⁻¹, respectively. (equivalent to 13.5 and 16.5 mm of rock weathered per 1000 years). Two serrated projectile points were found inbedded on the clayey soil surface of an adjacent ancient pond site. These artifacts resemble another projectile point found in southeastern Arizona which has been radiocarbon dated ~7,000 yr B.P. A minimum age for the pond and immediate surrounding topography is suggested to correspond with the end of the western subhumid pluvial period. The assessment of the geochemical budget provided a valuable framework for quantification of the various processes which interactively determine the rates of weathering and soil formation.

O presente trabalho visa se aprofundar em estudos para se obter uma melhor compreensão das maneiras que os processos de intemperismo químico na região tropical influem no rebaixamento do relevo. Este tema é de grande relevância e sua adequada compreensão é necessária para o avanço dos conhecimentos de geomorfologia da atualidade. Assim pretende-se a partir da compartimentação do relevo efetuar análises físicas e químicas de horizontes do solo e do manto de alteração, em perfis de contexto de litologia ígnea e metamórfica, efetuando comparações e demonstrando através dos resultados dos parâmetros selecionados de que forma o horizonte B se relaciona com o horizonte C do solo, bem como as semelhanças e diferenças ocasionadas pelos diferentes compartimentos litológicos. Para isso será efetuado um estudo de caso no Planalto do Paraitinga/Paraibuna-SP procurando correlacionar indicadores de maneira a demonstrar possíveis caminhos que forneçam informações quanto ao rebaixamento do relevo através de processos geoquímicos. / This study aims to deepen studies trying to understand ways of the chemical weathering processes influence the relief in the tropics. This matter have great relevance and need be better understanding to advance the geomorphology knowledge. Thus it is intended from the partitioning of relief make physical and chemical analysis of soil horizons and alteration mantle, in the context of igneous and metamorphic lithology profiles, making comparisons and demonstrated by the results of the selected parameters that form the B horizon is related to the soil horizon C as well as similarities and differences caused by different lithologic compartments. For it will be made a case study at the Plateau Paraitinga/Paraibuna-SP to correlate indicators in order to demonstrate possible ways to provide information regarding the lowering of relief through geochemical processes.

Soil development on upland landscapes in east-central Iowa Peoria Loess deposits has been occurring for approximately the last 12,500 years. Weathering zone and pedogenic processes depend on environmental factors such as climate, precipitation, time, parent material, biota, and topography, among others. Analyzing the weathering zones of modern and paleosol profiles provides insight into current and paleo-environmental processes. This study employs several bulk geochemical analytic techniques (XRF, pXRF, LIBS, ICP-MS) to examine the weathering profiles formed in modern Peoria Loess deposits and underlying weathering profiles formed during the Farmdale Interstadial and the Sangamon Interglacial. Results indicate advanced weathering occurred in the paleosol sequences of the Farmdale and Sangamon compared to the modern weathering zone, based on depletion and enrichment of elemental concentrations. The interstadial/last interglacial paleosol weathering profiles exhibit increased depletion in CaO, MgO, Na2O, and K2O compared to the Holocene weathering profile formed in Peoria Loess. Enrichment of CaO and MgO in non-pedogenically altered Peoria Loess deposits is a possible indication of rapid loess accumulation, representing insufficient weathering of deposited material synchronous with deposition. Post-depositional weathering and hydrogeological mechanisms may also account for this mid-profile enrichment, providing for some complexity for interpretation. Regional comparison between three sediment cores - an agricultural field, a restored prairie and a pioneer cemetery - exhibit minor land-use influence on geochemical evolution with the agricultural field core exhibiting greater relative depletion in most oxides in the upper one meter, compared to the other sediment cores. However, slight regional heterogeneity in parent material, vegetation cover, and slope position may also account for geochemical variations. Therefore, it is difficult to conclude how the last 150 years of extensive land-use from human activity has impacted weathering and pedogenesis in this region. Additionally, this study validates using pXRF technology on Quaternary weathering profiles, and documents its technological shortcomings which provides essential information for drawing interpretations from these data.

The contribution of dissolved organic carbon (DOC) to mineral weathering was investigated under the changing Eh and pH conditions in three subarctic fens, near Schefferville, Quebec. No evidence of increased weathering rates nor different weathering patterns were found in the fen basal sediment despite DOC-rich and low Eh (0 to +200 mV) conditions. / Solutions containing 50 mg DOC/L derived from subarctic fen peat, and of 50 and 300 mg DOC/L, derived from deciduous leaf litter were used as weathering agents. Clinochlore, microcline and the Fe-rich basal till from the Schefferville fens were used as weatherable mediums. The DOC rich solutions and controls (made of distilled water buffered to the same initial pH) were used to investigate the relative weathering ability of DOC-rich waters under aerobic and anaerobic conditions. The relative ability was determined by comparing the changing cation concentrations in the solutions.

Mémoire (M.Sc.T.)-- Université du Québec à Chicoutimi, 1992. / Bibliogr.: f. 70-77. Document électronique également accessible en format PDF. CaQCU