The mainline railway track between Dublin and Belfast in Northern Ireland was constructed during the 1850's. Substantial lengths of railway embankment were constructed over poor-quality peaty soils. This was accomplished using tree trunk fascines placed directly on the natural ground surface; with poor-quality local peaty soils used as light weight fill.<p>In recent years, Northern Ireland Railways have noticed that these sections of railway track have been deteriorating more rapidly than sections of the track where the foundations are more competent. The magnitudes of displacement of the track under train loading appear to be increasing gradually over time and train speeds have had to be reduced.<p>This thesis is based on the research done to monitor the response of these railway track and embankment structures to dynamic train loading. The displacements were monitored for two different embankments under a variety of loading conditions and for various seasonal conditions. These displacements were recorded using a sensor created for this task. The sensor consisted of a photo-sensitive array mounted on the sleepers and a laser, which was placed outside the area of influence of train loading, and shone on the photo-sensitive array. <p>Analytical (Winkler) modelling was conducted to determine the effects of train speed and the cause of the large train-induced displacements. Analytical and finite element modelling were used to determine the effectiveness of alternative methods of embankment stabilization.<p>The results from the analytical modelling suggest that the deformation of the embankment under train loading was not due to dynamic excitation, but static deformation of the poor-quality fill and soft foundation materials. From both the analytical and finite element modelling of possible remediation techniques, methods that stiffen the embankment and foundation material are shown to be the most effective at reducing the train induced deflection of the embankment.

Two peat cores from two mires with different characteristics, but both containingpermafrost features and located in the eastern part of the Tavvavuoma mire complex innorthernmost Sweden, were analysed for macrofossils and geochemical properties. Local vegetationsequences and changes in geochemical properties of peat were used to reconstruct development ofthe studied mires during the Holocene. The study includes measurements of water/ice content, bulkdensity, loss-on-ignition and C/N ratio. Radiocarbon dates for peatland inception and permafrostaggradation are available. The main purpose of the study is to verify permafrost history in thepeatlands. The results of the macrofossil analysis and values of C/N ratio indicate nutrient poor tointermediate fen environments in both studied mires until recently. Signs of permafrost upheavalwhich caused formation of xerophilic peat can be proved only since late 1950’s. The study resultscorroborate with other studies from Northern Fennoscandia and infer peatland initiation soon afterthe deglaciation of the area and permafrost-free conditions throughout entire Holocene untilrecently.

Peatlands are carbon sinks and occupy approximately 13% of Canada’s terrestrial surface of which 0.02% have been harvested for horticultural peat. The extraction of peat from natural peatlands alters the hydrology which affects the growth and survival of Sphagnum the primary peat forming vegetation. Ericaceous shrubs do not require specific water content and soil water pressure conditions for their existence and in cutover peatlands they occupy more than 70% of the surface. Rainfall interception, transpiration and root water uptake and redistribution are processes that alter water availability at the soil surface. The high abundance of shrubs at cutover peatlands will influence the surface water balance and more importantly soil water availability and, inevitably determine the success of Sphagnum reestablishment at the site. This study seeks to understand the role that ericaceous shrubs play in the surface hydrological balance at a cutover site and how these changes impact Sphagnum development. Rainfall interception, transpiration, litter layer evaporation and soil water flux was investigated in the field and lab. Approximately 334 mm of rainfall was measured over the season. The shrub canopy and litter had a maximum storage capacity of 4 and 1.2 mm respectively and intercepted ca. 36.7% (120 mm) of rainfall over the season. The effects of rainfall intensity and duration were more important than gross rainfall in determining the amount of water intercepted by the canopy, while the thickness and mass of the litter layer largely determined the storage capacity. Evapotranspiration from shrubs averaged 2.5 mm day-1 with a total of 211 mm over the season. Transpiration was 68% (142 mm) of total evapotranspiration losses, and represented the greatest water loss from the shrub canopy. From these analyses only 22% (72 mm) of rainfall is available for other soil processes and moss development. The evaporation under a litter cover is lower than bare peat and in the field represents water storage of 17 mm over the season. Reduced water input by litter interception is offset by the increased water storage under the litter. Laboratory analyses of soil water flux under ericaceous shrubs show that water loss under the shrubs was greater than bare peat. Water use under the shrubs was highest between -10 and -30 cm and was ca. 2 times greater than bare peat at the same levels. Volumetric water content (θ) decreased throughout the day and water use by shrubs during the day was twice that at night. The shrubs also maintained θ and soil water pressure (ψ) above the threshold values of 50% and -100 cm, respectively, needed for Sphagnum survival. Based on these analyses the shrubs will be beneficial to Sphagnum reestablishment and survival once the primary water losses have been compensated. I recommend raising the water table above -20 cm. In peatland restoration activities, at this level, water used between -10 and -30 cm can quickly be recharged and surface moisture maintained above threshold by capillary rise helping to offset water loss by interception and transpiration through capillary rise.

Two eruptions from Icelandic volcanoes have in the last years caused widespread dispersalof volcanic ash in the atmosphere. The transportation of tephra from Iceland to mainlandEurope is not an uncommon event and it can cause large disruptions to society. In thisthesis I present the ndings of a tephrochronological study of recent sediment from a bogcalled Trolls mosse in southern Sweden. The results show the presence of recent tephrafrom what is most likely the Grímsvötn eruption in May 2011, but geochemical analysisof the tephra could not conrm the exact origin of it, and a possibility that the Eyafjal-lajökull eruption also has contributed exists. By correlating atmospheric data about thelocation of the ash clouds produced during the eruptions and tephrochronological studiesof where tephra fallout has occurred could improve our understanding of tephra falloutdynamics and could help understand complex fallout patterns for past eruptions.

Peatlands are carbon sinks and occupy approximately 13% of Canada’s terrestrial surface of which 0.02% have been harvested for horticultural peat. The extraction of peat from natural peatlands alters the hydrology which affects the growth and survival of Sphagnum the primary peat forming vegetation. Ericaceous shrubs do not require specific water content and soil water pressure conditions for their existence and in cutover peatlands they occupy more than 70% of the surface. Rainfall interception, transpiration and root water uptake and redistribution are processes that alter water availability at the soil surface. The high abundance of shrubs at cutover peatlands will influence the surface water balance and more importantly soil water availability and, inevitably determine the success of Sphagnum reestablishment at the site. This study seeks to understand the role that ericaceous shrubs play in the surface hydrological balance at a cutover site and how these changes impact Sphagnum development. Rainfall interception, transpiration, litter layer evaporation and soil water flux was investigated in the field and lab. Approximately 334 mm of rainfall was measured over the season. The shrub canopy and litter had a maximum storage capacity of 4 and 1.2 mm respectively and intercepted ca. 36.7% (120 mm) of rainfall over the season. The effects of rainfall intensity and duration were more important than gross rainfall in determining the amount of water intercepted by the canopy, while the thickness and mass of the litter layer largely determined the storage capacity. Evapotranspiration from shrubs averaged 2.5 mm day-1 with a total of 211 mm over the season. Transpiration was 68% (142 mm) of total evapotranspiration losses, and represented the greatest water loss from the shrub canopy. From these analyses only 22% (72 mm) of rainfall is available for other soil processes and moss development. The evaporation under a litter cover is lower than bare peat and in the field represents water storage of 17 mm over the season. Reduced water input by litter interception is offset by the increased water storage under the litter. Laboratory analyses of soil water flux under ericaceous shrubs show that water loss under the shrubs was greater than bare peat. Water use under the shrubs was highest between -10 and -30 cm and was ca. 2 times greater than bare peat at the same levels. Volumetric water content (θ) decreased throughout the day and water use by shrubs during the day was twice that at night. The shrubs also maintained θ and soil water pressure (ψ) above the threshold values of 50% and -100 cm, respectively, needed for Sphagnum survival. Based on these analyses the shrubs will be beneficial to Sphagnum reestablishment and survival once the primary water losses have been compensated. I recommend raising the water table above -20 cm. In peatland restoration activities, at this level, water used between -10 and -30 cm can quickly be recharged and surface moisture maintained above threshold by capillary rise helping to offset water loss by interception and transpiration through capillary rise.

A patterned, partially-treed, fen in the mid-boreal region of central Saskatchewan was the site of renewed hydrological research from 2002 to 2004. Hydraulic conductivity, transmissivity, and storativity were determined through use of a surface loading test, pumping tests, and an enclosed field drainage test. None of these field tests have been previously described in the literature as having been used in peat environments. The combined results of field and laboratory drainage tests were used to obtain a general storativity with water table depth relationship in the upper peat layer. The hydraulic conductivity, measured with slug tests, the loading test, and pumping tests, is high near the surface, declining greatly with depth. These previously untested field methods have the advantage of representing volumes of peat from tenths of a meter to cubic meters. </p>Characterization of the hydrology of the peatland involved year round observations of water table, piezometric head, peat surface elevations, frost depth and peat temperatures. Fluctuations of the water table, and soil moisture changes produce changes in effective stress that lead to volume change in the highly compressible peat. This is particularly important for sites with thick peat deposits. Independent compressibility estimates were as high as 10-5 N/m2 in the upper peat. At three fen sites, changes in peat thickness were estimated from monthly estimates of effective stress change, using year round hydrological observations, and compared to measured annual peat thickness changes. Water table changes causing soil moisture changes, and freeze-thaw processes, explained the majority of peat surface movements.

The mainline railway track between Dublin and Belfast in Northern Ireland was constructed during the 1850's. Substantial lengths of railway embankment were constructed over poor-quality peaty soils. This was accomplished using tree trunk fascines placed directly on the natural ground surface; with poor-quality local peaty soils used as light weight fill.<p>In recent years, Northern Ireland Railways have noticed that these sections of railway track have been deteriorating more rapidly than sections of the track where the foundations are more competent. The magnitudes of displacement of the track under train loading appear to be increasing gradually over time and train speeds have had to be reduced.<p>This thesis is based on the research done to monitor the response of these railway track and embankment structures to dynamic train loading. The displacements were monitored for two different embankments under a variety of loading conditions and for various seasonal conditions. These displacements were recorded using a sensor created for this task. The sensor consisted of a photo-sensitive array mounted on the sleepers and a laser, which was placed outside the area of influence of train loading, and shone on the photo-sensitive array. <p>Analytical (Winkler) modelling was conducted to determine the effects of train speed and the cause of the large train-induced displacements. Analytical and finite element modelling were used to determine the effectiveness of alternative methods of embankment stabilization.<p>The results from the analytical modelling suggest that the deformation of the embankment under train loading was not due to dynamic excitation, but static deformation of the poor-quality fill and soft foundation materials. From both the analytical and finite element modelling of possible remediation techniques, methods that stiffen the embankment and foundation material are shown to be the most effective at reducing the train induced deflection of the embankment.

In this study agriculturally important Pseudomonas spp. which may solubilize phosphate and Azotobacter chroococcum which can fix atmospheric nitrogen were grown on waste beer with 4 different concentrations and conditions for best growth were determined. Having potential of use as biofertilizers, they were put in the carrier material peat and survivals of them were observed for 3 months at three different temperatures. Biofertilizer can be defined as a substance which contains living microorganisms which, when applied to seed, plant surface, or soil, colonizes the rhizosphere or the interior of the plant and promotes growth by replacing soil nutrients or making nutrients more available or increasing plant access to nutrients. In order to benefit from the biofertilizers, viable and active microorganisms in high numbers must be present which requires high quality inoculants. The carrier substrate is a critical part of the product formulation and must be capable of supporting high numbers of the intended microbe(s). It was found that Pseudomonas spp. can solubilize phosphate. Furthermore, conditions for best growth for both bacteria were determined as 30 % of waste beer. Peat was found as an appropriate carrier due to preservation of viable cells for 3 months at 0 &ordm / C, 20 &ordm / C and 30 &ordm / C. However, peat couldn&rsquo / t support high numbers of Pseudomonas spp. at 30 &ordm / C.

No description available.

Thesis (M.Sc.), Memorial University of Newfoundland, 2000. / Bibliography: leaves 133-144.