Thesis (Ph. D.)--University of Illinois, 1916. / Biographical.

Thesis (Ph. D.)--University of Illinois, 1916. / Biographical.

Two studies concerning low molecular weight organic acids in soils were conducted. In the first study, anion exclusion chromatography was used to separate and identify 12 common organic acids, and the accuracy, precision and detection limits of the method were determined. The method was found to be sensitive and accurate to between 1.5 and 9 ��M, depending on the acid in question. The stability of the selected acids was examined, and the large concentration changes observed underscore the importance of timely analysis of soil solutions. No significant interferences were encountered in the analysis of two soil solutions. In the second study, the reaction of a forest soil with oxalic acid at four concentrations was monitored for a period of 96 hours. A large release of aluminum, sulfate, and phosphate was observed, with the greatest release occurring with the highest concentration of added oxalate. Solution aluminum increased by up to a factor of twenty, and though [Al�����] values were consistent with control by thermodynamic equilibrium with an amorphous aluminum oxide phase, exchangeable Al appeared to be the source of the increase. Sulfate increased abruptly at the start of the reaction and continued to rise, though more slowly, throughout the study. Solution phosphate was increased by up to four times and was maintained at the elevated level throughout the study. Changes in both sulfate and phosphate concentrations were attributed directly to exchange with oxalate. The persistence of elevated phosphate concentrations after 96 hours indicates that the effects of oxalate production by mycorrhizae could have lasting effects on the nutrient status of a soil. / Graduation date: 2000

Atmospheric particulates have been known to act as cloud condensation nuclei (CCN) and therefore their presence can indirectly affect important processes such as global radiation balance through cloud formation. Soot particles are well known to be atmospheric constituents, but the hydrophobic nature of fresh soot likely prohibits them from encouraging cloud development. Soot aged through contact with oxygenated organic compounds may become hydrophilic enough to promote water uptake. In this study I have observed the interaction between a number of carboxylic acids and soot from different fuel sources and formation mechanisms. A low pressure fast flow reactor was used to control the contact between the solid phase soot and gas phase organics, while chemical ionization-mass spectrometry was utilized to monitor concentrations of gas phase organics. Most acids irreversibly deposited on the soot surfaces, and the uptake coefficient was measured in the wide range of 9.0 x 10-4 to 1.0 x 10-1. The Brunauer, Emmett, and Teller (BET) surface areas of the soots were measured and the soot bulk and surface chemical compositions were investigated with Fourier transform infrared (FTIR) spectroscopy and attenuated total reflection (ATR) spectroscopy to help explain differences in uptake. By comparing the mono and dicarboxylic acids and the information gathered from soot physiochemical properties I have discussed possible uptake mechanisms.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M.S.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 152-157). Also available on the World Wide Web.

Thesis (Ph. D.)--Johns Hopkins University. / Biographical.

Thesis (Ph. D.)--Johns Hopkins University, 1912. / Biographical.

Thesis (Ph. D.)--Johns Hopkins University. / Biographical.

Thesis (Ph. D.)--University of Michigan.