Thesis (Ph. D.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 106-115). Also available on the World Wide Web.

A study was undertaken on the pedogenesis of a Podzol sequence of soils on the West Coast of Vancouver Island. The area is one of abundant rainfall and rather luxuriant vegetation. The soils occur on relatively level topography (glacial fluvial deposits) and have varying degrees of development of placic (pan) horizons. The objectives of the study included characterization, classification and genesis of the soils, based on physical, chemical and mineralogical investigations. Four soils were chosen for the study. Three of the soils comprised the Ucluelet soil series, while one soil was a member of the Wreck Bay soil series. The soils were described morphologically, sampled and selected analyses were performed on the major genetic horizons. More detailed analyses, including differential thermal analyses, were conducted on the placic materials. The soils were classified into the Canadian Classification Scheme as as follows: Ucluelet I Placic Ferro-Humic Podzol Ucluelet II Orthic Humo-Ferric Podzol Ucluelet III Placic Humo-Ferric Podzol Wreck Bay Gleyed Placic Ferro-Humic Podzol Analyses of the placic materials indicated, that although the material appeared vitreous in the field, no crystallinity could be determined by X-ray diffraction. It appeared that the major component of the placic horizon is composed of iron and organic matter, probably in some intimate association. It was observed that the placic horizon could form in materials of initially low iron contents. From the foregoing observations the following chronosequence of soil development appears to be justified: Orthic Humo-Ferric Podzol (Ucluelet II) → Placic Humo-Ferric Podzol (Ucluelet III) → Placic Ferro-Humic Podzol (Ucluelet I) → Gleyed Placic Ferro-Humic Podzol (Wreck Bay) The differences in pedogenic age of the three Ucluelet sites can be attributed to degrees of "churning" by the trees at these sites. / Land and Food Systems, Faculty of / Graduate

Three soils occurring on a climosequence were studied to clarify certain aspects of Podzol genesis and Podzol classification. Data on physical, chemical, and soil solution characteristics of the three soils were collected and analysed. All measures of iron and aluminum were analysed and presented as mass per horizon. Rates of movement for calcium, magnesium, sodium, potassium, iron and aluminum between the canopy, forest floor, B₁ and B₂ horizons were also measured. The interpretations of different measures of iron and aluminum as an index of Podzol expression were shown to be inconsistent. A simple linear model was developed and applied to data from the three soils. The model defined the balance of additions, losses, transformations, and translocations within and between horizons for each site. The model results supported the following hypotheses: 1) The balance of additions, losses, translocations, and transformations vary across the climosequence. 2) The three soils studied can be identified by the balance of processes acting to produce sesquioxide rich B horizons. 3) Current Podzol classification criteria do not reflect differences in the balance of these processes. The model did not support the hypothesis that rates of biochemical cycling would be reflected in Podzol B horizon expression. Two distinct balances of processes forming iron and aluminum rich B horizons were shown to occur. In one site iron and aluminum accumulate primarily as a result of preferential loss of other soil constituents; in the other sites iron and aluminum are dominantly the product of eluviation from the Ae horizon and deposition in the B horizons. Current classification criteria grouped the two soils showing the most strongly contrasting genetic processes together as Brunisols while the intermediate balance was classified as a Podzol. The reasons for this inconsistency are discussed. / Land and Food Systems, Faculty of / Graduate

No description available.

The interplay between geology and biology has shaped the Earth during billions of years. Microbe-mineral interactions are prime examples of this interplay and underscore the importance of microorganisms in making Earth a suitable environment for all forms of life. The present thesis takes an interdisciplinary approach to obtain an integrated understanding of microbe-mineral interactions. More specifically it addresses how the composition and distribution of biogenic weathering agents (siderophores) differ with regard to soil horizon and mineral type in situ, what siderophore type soil microorganisms produces under laboratory conditions, what role microbial surface attachment plays in mineral weathering reactions and what central roles and applications siderophores have in the environment. Podzol, the third most abundant soil in Europe, and most abundant in Scandinavia, was chosen for a field experiment, where three minerals (apatite, biotite and oligoclase) were inserted in the organic, eluvial and upper illuvial soil horizons. The study started with an investigation of the siderophore composition in the bulk soil profile and on the mineral surfaces (paper I), which was followed by a study of the siderophore producing capabilities of microorganisms isolated from the soil profile under laboratory conditions (paper II). Subsequently, a study was done on the impact of microbial surface attachment on biotite dissolution (paper III). Finally, the roles of siderophores in nature and their potential applications were reviewed (paper IV). The major findings were that the concentration of hydroxamate siderophores in the soil attached to the mineral surfaces was greater than those in the surrounding bulk soil, indicating that the minerals stimulate the microbial communities attached to their surfaces to produce more siderophores than the microorganisms in the bulk soil. Each mineral had a unique assemblage of hydroxamate siderophores, that makes the mineral type one of the main factors affecting siderophore composition in the natural environment. Siderophore production varied between the microbial species originating from different soil horizons, suggesting that the metabolic properties of microbes in deep soil horizons function differently from those at upper soil horizons. Microbial surface attachment enhanced the biotite dissolution, showing that attached microbes has a greater influence on weathering reactions in soil than planktonic populations. In conclusion, our findings reflected that the complicated relationship between microorganisms and mineral surfaces reinforces the central theme of biogeochemistry that the mineral controls the biological activity in the natural environments. However, the importance of these relationships to the biogeochemical systems requires further investigation. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: In press.</p><p> </p>

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Thesis (M.Sc.) -- Memorial University of Newfoundland. / Typescript. Bibliography: leaves 106-115. Also available online.

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Os Espodossolos são os solos de maior ocorrência na planície costeira do litoral do Estado de São Paulo e são caracterizados pela presença de um horizonte espódico (Bh ou Bhm). Poucas são as informações relacionadas à gênese destes solos em regiões tropicais, assim como da composição química da matéria orgânica (MO) nos mesmos e da influência dos micro-organismos em sua formação. É possível que micro-organismos envolvidos na degradação seletiva da MO sejam importantes para a gênese de Espodossolos, como observado anteriormente em Espodossolos de Bertioga e Ilha Comprida. O primeiro estudo teve como objetivo avaliar a variação espacial da estrutura das comunidades e a abundância de bactérias e fungos em três perfis de Espodossolos sob drenagem intermediária, nos diferentes horizontes e nas manchas brancas através de PCR-DGGE e quantificação por qPCR dos genes rRNA 16S de bactérias e ITS de fungos. O segundo estudo teve como objetivo avaliar a variabilidade espacial das comunidades de bactérias nos horizontes e nas manchas brancas de Espodossolos sob três regimes de drenagem, e determinar se a diversidade genética e estrutura das comunidades de bactérias estão associadas à composição molecular da MO nessas regiões, através do sequenciamento massivo da região V4 do gene do rRNA 16S de bactéria e análise de compostos orgânicos por pirólise-GC/MS. As estruturas das comunidades bacterianas, determinada por PCR-DGGE, nos diferentes horizontes de cada perfil foram mais similares entre si do que nos mesmos horizontes em diferentes perfis de Espodossolos. A estrutura das comunidades fungos não apresentou diferenças significativas, independente da localidade do perfil e profundidade dos horizontes. A abundância de cópias do gene rRNA 16S e região ITS, determinada por qPCR, foi maior no horizonte A do que no horizonte Bh, para os três perfis de Espodossolos estudados. Apesar de não haver diferenças significativas na estrutura das comunidades, grupos específicos de bactérias e fungos podem estar envolvidos na degradação seletiva da matéria orgânica nos diferentes horizontes, bem como nas manchas brancas e suas adjacências. A estrutura das comunidades de bactérias, determinada por sequenciamento massivo do gene rRNA 16S, nos horizontes mais superficiais (A e AE) foi distinta daquela observada nos horizontes mais profundos (EB, BE e Bh). Porém, as comunidades bacterianas nas manchas brancas e suas regiões adjacentes foram mais similares entre si, do que em relação as comunidades bacterianas nos horizontes, em todos os perfis analisados, independente do regime de drenagem. Acidobacteria, Proteobacteria e Actinobacteria foram os filos mais abundantes nos solos estudados. Actinobacteria e Alphaproteobacteria mostraram associação positiva com moléculas orgânicas derivadas da pirólise da lignina, as quais foram mais abundantes nos horizontes superficiais (A e AE), enquanto Acidobacteria mostrou associação positiva com compostos mais recalcitrantes encontrados em horizontes mais profundos (Bh), sugerindo um papel específico e diferenciado de cada grupo bacteriano na degradação de compostos orgânicos específicos. Os resultados desses estudos sugerem que grupos bacterianos específicos podem estar envolvidos na gênese de Espodossolos através da degradação de compostos orgânicos específicos em diferentes horizontes. / Podzols are highly frequent soils in the coastal plains of the São Paulo State, and are characterized by the presence of a spodic horizon (Bh or Bhm). Studies on the pedogenetic processes in Podzols of tropical regions are scarce, as well as studies on the molecular characterization of their organic matter (OM) and on the microorganisms involved in their genesis. It is possible that microorganisms involved in the selective degradation of the soil OM are important for the genesis of Podzols, as previously observed in Podzols of Bertioga and Ilha Comprida. The aim of the first study was to evaluate the spatial variation of the community structure and abundance of bacterial and fungi in the different horizons, bleached mottles and their immediate vicinity of three Podzol profiles under intermediary drainage regime, using PCR-DGGE and qPCR of the bacterial rRNA 16S gene and fungal ITS region. The aim of the second study was to determine the spatial variability of the bacterial communities in the horizons and bleached mottles of Podzols under three drainage regimes, and whether the bacterial genetic diversity and community structure were associated to the molecular OM composition, using high-throughput sequencing of the V4 region of the bacterial 16S rRNA gene and analyses of organic compounds by pyrolysis GC/MS. The structure of bacterial communities, determined by PCRDGGE, in the different horizons of each soil profile were more similar to each other than in the same horizons of different soil profiles. The fungal community structures did not show significant differences, independent of the soil profile location and horizons depth. Abundance of copies of the bacterial 16S rRNA gene and fungal ITS region, determined by qPCR, was higher in the A horizon than in the Bh horizon, for the three Podzol profiles studied. Even though there were no significant differences in community structures, specific groups of bacteria and fungi may be involved in the selective degradation of organic matter in different horizons, bleached mottles and their immediate vicinity. The bacterial community structures, determined by highthroughput sequencing of the 16S rRNA gene, in the surface horizons (A and AE) were distinct of that in the deeper horizons (EB, BE and Bh). However, the bacterial community structures in the bleached mottles and their immediate vicinity were more similar to each other than to the community structures in the horizons, in all profiles studied, regardless of the drainage regime. Acidobacteria, Proteobacteria and Actinobacteria were the most abundant phyla in the soils studied. Actinobacteria and Alphaproteobacteria showed a positive relationship organic compounds derived from lignin degradation, which were more abundant in the surface horizons (A and AE), whereas Acidobacteria showed a positive relationship with more recalcitrant compounds detected in deeper horizons (Bh), suggesting a specific and distinct roles of each bacterial group in the degradation of specific organic compounds. The results of these studies suggest that specific bacterial groups may be involved in the genesis of Podzols by degrading specific organic compounds in different horizons.