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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Effects of sodium, potassium, ammonium on dispersion of calcareous soils

Ibrahim, Ismail K January 2011 (has links)
Typescript. / Digitized by Kansas Correctional Industries
12

The effects of decling environmental pH on coral microstructure and morphology

Tibbits, Matthew A 01 December 2009 (has links)
Coral reefs are faced and will be faced with many challenges this century. One danger is the rapid decline of oceanic pH due to anthropogenic sources. The more acidic the environment becomes, the harder reefs and coral (order: scleractinia) in particular will be hit. Experiments to measure the effect on scleractinian coral were performed to glean a better understanding of the processes that will be affected by our acidifying oceans. Additionally, the search for and analysis of coral microstructure and micromorpholgy were carried out in an attempt to understand homology within an environmentally responsive taxa.
13

The effects of earthworms on soil structure in an upland grassland

Spring, Christian Alexander January 2003 (has links)
As Charles Darwin first noted in 1881, earthworms through their burrowing and casting activities, play an important role in the creation and maintenance of soil structure. Burrowing activity leads to the reorganisation of voids and creation of macropores within the soil. This has implications for aeration and the flow properties of water through soils. Casting activity affects the structural stability of soil through the stabilisation of aggregates. The overall aim of this research project has been to investigate the effects of earthworm activity and diversity on void space and aggregation in an upland soil. This research has been carried out as part of NERC's Thematic Programme on Soil Biodiversity. The field site was located on the Macaulay Land Use Research Institute's experimental farm at Sourhope in the Scottish Borders. Three experiments were designed to investigate the impact of earthworms on soil fabric, with each experiment representing an increased level of system complexity. The simplest experiment took place in a controlled environment and used an artificial soil and different earthworm treatments. The second level of system complexity used soil from Sourhope which had its structure removed, and then earthworm and liming treatments applied. The most complex experiment also used Sourhope soil and liming and earthworm treatments, except in this case the soil was undisturbed. The effects of earthworms and liming on void space were characterised using saturated hydraulic conductivity to measure macroporosity, and image analysis to quantify total porosity and void size distribution. Aggregation was assessed through aggregate stability and point counts of earthworm excremental features. The effect of earthworm inoculation in the simplest experiment led to the reorganisation of voids through increased abundance of voids > 2 mm2 in area, and decreases in the proportion of voids with an area < 2 mm2. No significant effects were observed on aggregate stability. The effect of liming in the experiment using disturbed soil was to increased abundance of voids > 2 mm2. No significant effects were observed on aggregation due to either liming or earthworm inoculation. In the most complex experiment, neither liming nor earthworm inoculation led to changes in void space or aggregation, except for an increase in saturated hydraulic conductivity and therefore macroporosity due to earthworm inoculation. The overall conclusions from this research were that as system complexity increased, then the effects of the treatments on void space and aggregation became more difficult to isolate. Nevertheless, it was clear that liming significantly affected void space through increased abundance of earthworms. Out of the two treatments applied to the Sourhope soil, liming had the strongest effect on both earthworm abundance and void space.
14

Cryogenic alteration of a frost susceptible soil.

White, Thomas Leslie, Carleton University. Dissertation. Geology. January 1992 (has links)
Thesis (M. Sc.)--Carleton University, 1992. / Also available in electronic format on the Internet.
15

Site formation processes at three Viking Age farm middens in Skagafjörður, Iceland

Sawyer, Alicia Hart 12 February 2016 (has links)
Archaeological sites are not static records of the past. They exist within a dynamic environment, and, as part of this environment, they undergo changes upon deposition. In order to make confident interpretations of past human behavior based on patterns observed in the archaeological record, it is first necessary to determine if these patterns were produced by human behavior or if they are the result of geogenic or biogenic process following burial. This investigation of site formation processes of farm middens at three Viking Age farms (Reynistaður, Stóra-Seyla and Syðra Skörðugil) in Skagafjörður, Northern Iceland, uses micromorphological analysis of thin sections to discern between cultural and natural processes which have contributed to the formation and preservation of the middens. My interpretations of the depositional and post-depositional processes of these three middens is based on micromorphological analysis of thin sections of 11 resin-impregnated intact sediment samples.
16

A Taxonomic Revision of <i>Tovomita</i> (Clusiaceae)

Gahagen, Benjamin A. 17 September 2015 (has links)
No description available.
17

Micromorphology of soil fabric at tree root-soil interface /

Blevins, R. L. January 1967 (has links)
No description available.
18

The nature, distribution and significance of amended and anthropogenic soils on old arable farms and the elemental analysis of black carbonised particles

Pears, Ben January 2009 (has links)
Ever since the development of farming humans have been implicitly linked with the landscape. Influences include the manipulation of natural environments by woodland clearance, field developments and animal husbandry. Development can also be determined by the identification and distribution of soils developed and modified by the addition of organic and inorganic components. Anthropogenic or amended soils have been identified in many forms across north west Europe that retain distinctive physical and chemical indications of historical agrarian and settlement history. This thesis researched the on-site distribution of anthropogenic and amended soils across different landuse areas and identified and quantified a range of black carbonised particles in order to investigate their role in the soils ability to retain high elemental concentrations of manuring and elements associated with domestic activity and industrial processes. Three sites in contrasting environments were chosen for analysis; in Fair Isle, the Netherlands and Ireland on the basis of an excellent agararian and settlement history and previous analysis of anthropogenic soils. The fieldwork results showed extremly deep plaggen soils in the Netherlands but considerably shallower horizons of amended arable soils on Fair Isle and in Ireland contrary to previous analysis. There was however, clear evidence of a reduction in anthropogenic and amended soils with increased distance from the farm centres as a result of less manuring. The soil pH, organic matter, particle size, magnetic susceptibility and bulk elemental analysis results showed unexpected increases in the amended soils of Fair Isle and Ireland and reflected a similar manuring process. In the Netherlands the deep plaggen soils had very low results reflecting modern arable farming. The micromorphology results illustrated distinctive characteristics associated with localised manuring techniques. On Fair Isle and in Ireland the main organic manuring material was peat and burnt peat, whereas in the Netherlands the plaggen soils were predominantly composed of meadowland and heathland turf. At all three sites there was a large number of black carbonised and black amorphous inclusions and point counting and image analysis results showed a decrease with depth and distance from settlement nucleii mirroring the fieldwork observations. The elemental analysis conducted has proved to be an extremly useful tool for the identification of various forms of black carbon and for identifying the provenance of high elemental concentrations. The oxygen:carbon ratios confirmed the origins of organic components used in the development of the amended and anthropogenic soils and the elemental analysis showed that at each site over 80% of visually unidentifiable amorphous black carbon particles were heavily decomposed carbonised inclusions. Overall the elemental concentrations within the black carbonised particles was very low but this reflected the elemental results found in the bulk soils and the inclusions contained higher concentrations of P, Ca, K, Fe and Al and considerably lower concentrations of elements associated with domestic activity or industry Zn, Cu, Ba, Cr, As and Pb.
19

A Quantitative Assessment of Site Formation at the Dmanisi Archaeological Site, Republic of Georgia

Crislip, Peter S. 08 1900 (has links)
The focus of this thesis was to gather and analyze micromorphological and petrographic data on soils at the archaeological site of Dmanisi in order to better understand the extent to which the deposition and alteration of the sediments has affected the preservation of artifacts and faunal remains. A major goal of this research was to test hypothesis related to why bone material is discovered in some strata and not in others. This research focuses on the application of micromorphology (supplemented with other methods) to the soils through the use of petrographic analysis of thin sections and scanning electron microscopy. These techniques complement previous field analyses by providing a quantitative assessment of individual strata through point counting and chemical mapping. The results of this research support the hypothesis that the sediments are predominantly mafic ashes, while showing that there is very little soil development in the strata. This suggests quick episodic burial in a relatively dry climate, confirming the hypothesis for a short time sequence in the strata. Additionally, differential weathering probably did not play a significant role in the differential abundance of bone remains among the strata at Dmanisi.
20

Caracterização macro e micromorfológica do solo para compreensão de processos erosivos lineares, topossequência Manacá, São Carlos - SP / Macro and micromorphological characterization for understanding linear erosion, Toposequence Manacá, São Carlos/ SP

Cerminaro, Ana Clara 15 February 2016 (has links)
A presente pesquisa tem como objetivo compreender a dinâmica de comportamento do solo sob escala macro e micromorfológica visualizados em topossequência, no que concerne aos agentes morfológicos que condicionam e contribuem para deflagração de processos erosivos. A área de estudo está inserida na sub-bacia hidrográfica do Laranja Azeda localizada na região centro-leste do estado de São Paulo, no município de São Carlos/SP, e têm fundamental importância por pertencer à bacia hidrográfica do Ribeirão Feijão, importante manancial urbano para a cidade. O planejamento de uso e ocupação adequados aos fatores físicos que compõe a dinâmica desta paisagem são essenciais visando a conservação e preservação dos recursos hídricos ali existentes, onde a expressiva ocorrência de processos erosivos são objetos de preocupação, já que estes podem causar assoreamento de rios e reservatórios. Utilizando uma metodologia multiescalar para seleção da área de pesquisa em detalhe e compreensão da organização e dinâmica da cobertura pedológica, foram utilizados os procedimentos propostos pela Análise Estrutural da Cobertura Pedológica e conceitos e técnicas da micromorfologia de solos. Verifica-se que a distribuição dos solos na Topossequência Manacá está estritamente correlacionada à transformação vertical do materialde origem em solo, em cuja vertente existe uma diferenciação litológica que condiciona a morfologia diferenciada, tanto em escala macromorfológica quanto micromorfológica. O terço superior e médio da vertente está associado à depósitos colúvio-eluvionaresda Formação Itaqueri, onde desenvolve-se um Latossolo Vermelho Amarelo. Já o terço inferior da vertente corresponde a um solo formado a partir dos arenitos da Formação Botucatu, sendo enquadrado enquanto Neossolo Quartzarênico. Com o auxílio técnicas de análise bidimensional de imagens retiradas das lâminas delgadas de solo, foi possível visualizar e quantificar a macroposidade ao longo da vertente, importante atributo morfológico que controla os fluxos de água e são agentes condicionantes para o desenvolvimento de processos erosivos. Conclui-se que a ocorrência de voçorocas no terço médio inferior da vertente é a materialização em forma de processos erosivos deste comportamento diferencial da massa do solo, onde portanto, na Topossequência Manacá a busca de equilíbrio dinâmico na vertente é induzida pela dinâmica genética evolutiva das formações geológicas que sustentam a paisagem, desencadeada em processos erosivos que tendem a progredir em desequilíbrio, a depender do manejo estabelecido para o local. / This dissertation aimed to understand the soil behavior under macro and micromorphological dynamic viewed in topossequence, in what concern the morphological agents that influence and con-tribute to outbreaks of erosion. The study area is within the sub basin of the brook Laranja Azeda, located in the central eastern region of São Paulo, in São Carlos / SP. Its study is of fundamental importance because it belongs to the basin of Ribeirão Feijão, an important source of water supply to the city. Planning the land use and occupation suited to the physical factors that compose the land-scape dynamics are essential to promote the conservation and preservation of water resources therein, where the significant occurrence of erosive processes are objects of concern, as these can cause silta-tion of rivers and reservoirs. It was applied a multiscale methodology to select the research area in detail for understanding the organization and soil cover dynamics, therefore, the procedures proposed by the Structural Analysis of Pedologic Coverage and also concepts and techniques of soil micromor-phology were used. It is found that the soil distribution in Toposequence Manacá is strictly correlated to the vertical transformation of the source material in soil, in which there is present a lithology dif-ferentiation, which makes the differentiated morphology both as macromorfológica micromorpho-logic scale. The upper and middle hillside its associated with colluvial alluvial deposits of Itaqueri formation, which develops a yellow red Oxisol. But the lower third of the hillside corresponds to a soil formed from the sandstones of the Botucatu Formation, being framed as Quartzipsamment. With the aid techniques bidimensional image analysis of thin sections taken from soil, it was possible to visualize and quantify macroposidade along the slope, a major morphological traits that controls wa-ter flow and is a conditioning agent to develop erosion. It is concluded that the occurrence of gullies in the lower and middle slope is the embodiment, in the form of erosion process, of this differential behavior of soil mass, where, in the Toposequence Manacá, the aim for dynamic equilibrium in the hillside is induced by genetic evolutionary dynamics of geological formations that underlie the land-scape, triggered in erosive process that tend to evolve unbalanced depending on the management of the land use established for the area.

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