Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 124-128). Also available in electronic version.

Thesis (M. Sc.)--University of Hong Kong, 2001.

The main purpose of this study was to delineate ecosystem forest types within the forest associations of the Coastal Western Hemlock Zone. This aim was realised through the study of the ecotope of 116 sample plots in fifteen different associations. The study involved examination of topographic position and macroscopic soil properties in all sample plots. Twenty-four soil profiles were analysed for chemical properties. The forest associations were divided into two or more forest types or kept as a single forest type. This was done by the author and coworker, L. Orloci, primarily on the basis of ecoptopic information. Results of the study of edaphic factors in relation to plant associations indicate that the moisture regime, soil depth, organic matter/nitrogen ratio and potassium concentration of the soils are the most important factors edaphically differentiating the forest associations. Soil succession studies included in this work suggest that the climate, the kind of vegetation and water economy of the soil determine the course of soil development. Soil succession may initiate on six essentially different kinds of substrata, in the Coastal Western Hemlock Zone. Soil forming processes contributing to development of soils are podzolization, gleyzation, melanization and peat formation in the study area. / Science, Faculty of / Botany, Department of / Graduate

An ap horizon of a soil collected from a highly mineralized area was fractionated into five organic and mineral components and the distribution of cu, zn, pb, ca and mg within these components was determined. Zn and ca were removed to a considerable degree in the 0.1n hcl extract. Of the five metals, cu and pb were the only ones present which combined with organic matter to any considerable degree. Of the five organic and mineral components, fulvic acid was shown to display the greatest complexing activity. Although gel filtration has been used extensively in the field of biochemistry, it was shown that the metal retaining properties of the various sephadex and agar gels used caused the technique to be unsuitable for the separation of naturally occurring metal-organic complexes. In addition the distribution of fe, cu and zn within the profiles of two soils from less mineralized areas was determined but the low levels of metal found did not permit a direct investigation of their metal-organic complexes. In order to study in detail metal-0rganic matter reactions, humic acids were extracted from several of the above soils. Functional group analysis coupled with elemental analysis for c, h, N and 0 in these humic acids revealed that a large percentage of the oxygen was unaccounted for in carboxylic acid and phenolic Hydoxylic groups, thus indicating the presence of other oxygen containing groups. Infrared spectra showed decreases in the amount of aliphatic material present with increasing maturity of the humic acids and also gave supporting evidence of complex formation upon the addition of cu. The humic acids were used in a series of incremental potentio- Metric titration experiments which monitored the pattern of proton release in response to copper additions at a series of ph levels. The resultant curves for humic acids of various origins were alike in their general shapes but displayed differences in detail which were especially marked between the juvenile and the more mature acids. Whereas in all cases of humic acids derived from mineral soils the proton release increased with ph, the peat humic acid displayed a greater proton release at ph 5.0 than at ph 6.0. The shapes of the curves obtained with humic acids were compared with those obtained in similar experiments from a series of model compounds of known chemical composition and were found to approximate most closely the patterns derived from salicylic acid and phthalic acid. This provides additional evidence for the hypothesis that salicylic and phthalic acid-like functional groups play a significant role in the formation of metal-organic complexes in soils. / Land and Food Systems, Faculty of / Graduate

No description available.

No description available.

No description available.

No description available.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1978.

No description available.