The first chapter is a brief review of the geology, geography and the soils in Iceland, with particular reference to peat soils. The field work (Chapter 2) included measuring the thickness of organic layers between dated tephra layers and it was found that the mean rate of thickening of the peat was slowest 0.1 mm/year in the period 4500 to 2900 B. P., but fastest 0.26 mm/year in the period since 1104 A. D. Two profiles were selected for detailed study, one in north Iceland, and the other in west Iceland. Micromorphology, physical, and chemical properties were investigated, see-Chapters 3,4 and 5 respectively; and a review of peat soil classification and the application to the soils studied is given in Chapter 6. The main constituents observed in the thin sections were underground plant organs, fine organic material, and mineral material. Woody, cork, epidermal and lign ifi ed tissues were best preserved, parenchymatous tissue had predominantly disappeared, but was present in some leaf and herbaceous root residues. Conspicuous secondary mineral phenomena included bog iron, pyrite and siderite; and in Chapter 7a hypothesis is proposed for the formation of s ider it e. The range of hydraulic conductivies was from about 9.10-3 to 1_ 10-4 cm sec-1 . The moisture content at saturation was mainly > 90 , and 10 to 20; 4 at pr 4.2. Bulk density was mainly 0.1 to 0.2 g cm-1 in organic layers and up to 0.5 g cm-1 in those rich in mineral material. Most samples shrunk to less than half the original volume upon oven drying and it was concluded that it is important to consider shrinkage when moisture retention is determined. The pH in water was highest at 6.8 in the top layer of the profile in north Iceland, but was mainly 4.4 to 5.0 in the organic layers. The loss on ignition of the organic layers varied mainly from 40; ') to 90 The C/N range was normally 17 to 30, but lowest at 15 in the top layer of the profile from North Iceland

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

M.Sc. / The objectives of this thesis were to map, categorise and document the peat resources of Maputaland in terms of: • extent and distribution of peat occurrences • description of peat types • a proximate analysis of the energy content • chronology: C 14 ages and accumulation rates • utilisation of the peat resource. The study area is situated in Maputaland, on the northern KwaZulu-Natal coastline and is confined by the South African-Mozambique boundary in the north, the Indian Ocean in the east, the Mfolozi River in the south and the Lebombo Mountains in the west. Peatlands were identified and delineated on 1 :50 000 maps and aerial photographs. Peat cores were taken to describe peat profiles and cross-sections. The physical characteristics of the peat were described in the field according to colour, moisture content, fibre length and fibre content and compared with the Von Post humification scale. Selected samples were C14 dated and the C14 ages used to determine peat accumulation rates and to characterise the peatlands together with calorific value (MJ/kg) (air-dried samples) and proximate analysis. Two hundred and sixty-six peatlands were investigated during this study. Peat thicknesses varies from 0.5 to 10m and wetlands vary in size from a few hectares up to 8 800 ha. The peat resource is inferred to be 158-million m3 moist peat and it comprises 60% of South Africa's peat. Peatlands occur in areas where the rainfall exceeds 600 mm/year and at elevations between sea level and 50 m above mean sea level.

This thesis examines whether short term (one to three weeks) microbial sensitivity to temperature and carbon (C) inputs can be predicted from peat characteristics driven by nutrient gradients. The aim was to determine if relationships exist between peat macronutrient (C, nitrogen (N), phosphorus (P)) concentrations, microbial community composition and the microbial response to changes in temperature and C supply. The focus of this thesis was on using peat macronutrient concentrations as explanatory variables as this is a metric which is easy to define and measure consistently, unlike other factors such as peat C quality and availability of nutrients. It was observed that, over short timescales, microbial respiration rates in peat soils increased in response to warming, nutrient (N and P) additions and increased labile C supply. In the first two experimental chapters it was found that peat respiration was sensitive to temperature, with increases of 10°C shown to increase microbial CO2 production by factors of 2.8 to 4.4. In the final two experimental chapters priming effects in peat were examined with C additions found to stimulate microbial activity and increases in peat derived CO2 flux, which could be attributed to priming. Despite the wide variation in nutrient concentrations in the peat soils examined no clear relationships between peat nutrient properties (total and available concentrations) and the magnitude of the microbial responses were observed.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 174-187).

Thesis (Ph.D.) -- La Trobe University, 2006. / Research. "A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy, [to the] Centre for Applied Alpine Ecology, Department of Agricultural Sciences, School of Life Sciences, Faculty of Science, Technology and Engineering, La Trobe University, Bundoora". Includes bibliographical references (leaves 172-186). Also available via the World Wide Web.

The Florida Everglades is considered as a vulnerable wetland composed primary of organic rich peat soils, experiencing saltwater intrusion. Impact of increasing salinity on the strength and deformation properties of peat is unknown. A laboratory study was undertaken to evaluate how the growing salinity level due to sea level rise may alter the compressibility behavior of the Everglades soils. Sixteen 1-dimensional oedometer tests were conducted on undisturbed Everglades peat soils in two phases. Phase I included samples from Site 1 (saltwater) and Site 3 (freshwater) without any salinity addition. Phase II consisted of soil from Site 3 (freshwater) saturated in six different levels of salinity artificially added to the samples. Compressibility properties investigated in this study include compression index (Cc), coefficient of consolidation (Cv), hydraulic conductivity (K), and the Ca/Cc ratio. In general, it was observed that the increase in salinity beyond a threshold value tends to increase the soil compressibility properties, indicating a possible reduction in soil stability with saltwater intrusion. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

While repeated transgressive and regressive sea level cycles have shaped south Florida throughout geological history, modern rates of sea level rise pose a significant risk to the structure and function of the freshwater wetland ecosystems throughout the low-lying Everglades region. Current regionally corrected sea level projections for south Florida indicate a rise of 0.42m by 2050 and 1.15m by 2100, suggesting the salinization of previously freshwater areas of the Everglades is conceivable. As freshwater areas become increasingly exposed to saltwater they experience shifts in vegetation composition, soil microbial populations, plant productivity, and physical soil properties that ultimately result in a phenomenon called peat collapse. Recent work in the Everglades has sought to further explain the mechanisms of peat collapse, however the physical changes to the peat matrix induced by saltwater intrusion are still uncertain. Moreover, the combination of physical alterations to the peat matrix associated with peat collapse and shifts in wetland salinity regimes will also likely disrupt the current carbon gas dynamics of the Everglades. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

No description available.

Methanogenesis was studied in soils from two sawgrass wetlands of the Florida Everglades. Marl soils exhibited a significantly higher potential rate of methanogenesis than peat soils. In these wetlands, methanogenesis: (1) decreased rapidly with increasing soil depth, (2) increased at higher temperatures and lower Eh, (3) was stimulated by organic compounds (cellulose, glucose and acetate), and (4) remained unaffected by added ammonium. Lowering the Eh in the peat and marl soils with sulfide or sulfate stimulated methanogenesis. In January 1990, phosphate caused a significant increase in methanogenesis. The potential rates of methanogenesis decreased to undetectable levels when water levels dropped below the surface, and peaked one month after the start of the wet season. Methanogenesis appeared to be a relatively important process in carbon cycling in marl soils and these soils do not accumulate peat. Therefore, one possible explanation for peat accumulation in sawgrass wetlands may be their low rates of methanogenesis.