The Constant Rate of Strain (CRS) test is currently the most widely used method for determination of consolidation parameters in Sweden. These parameters are used to calculate the probable settlements and behavior of soils. With the Swedish standard strain rate, the duration of a single the test is about 24h, but a higher strain rate would allow for more tests to be performed in the same amount of time. For all clays in Sweden, the Swedish standard for the CRS test suggests a fixed rate of strain that is independent of soil properties, while the North American standard proposes a strain rate that generates a pore pressure ratio of 3-15%. Soil properties such as water content, liquid limit, sensitivity and shear strength vary greatly between different regions of Sweden. It would be beneficial if these properties could be used to find the ideal strain rate for the CRS test. Performing the tests at a higher strain rate, and thus performing more tests within a shorter amount of time, would save both time and money. In this report, 24 CRS tests are performed on three different clays with distinctive properties. Each clay is tested with three different strain rates: the Swedish standard rate of 0.680%/h, a higher rate of 3.00%/h and a lower rate of 0.154%/h. The results are evaluated according to both standards, and are compared and analyzed to determine whether there is any indication that the strain rate can be selected based on the soil properties. The results indicate that the selection of the strain rate is dependent on the soil properties. In addition, the majority of the tests can be conducted with higher strain rates than what is required by the Swedish standard and still manage to lie within the 3-15% limit of the pore pressure ratio, which is acceptable for the North American standard. However, the preconsolidation pressure does rise with increased strain rates, which can generate problems and erroneous results when calculating the settlements. A more extensive testing program with CRS tests and full-scale field tests must be carried out before any recommendation of a higher strain rate can be made.

Ground Penetrating Radar (GPR) is an effective tool to measure the geological properties. A lot of information can be interpreted from the GPR data, such as soil water content. One of the common approaches is to determine the apparent electrical permittivity from the transmission velocity of the impulse electromagnetic wave, and to use empirical relationships to estimate the soil water content. For example, Ferre equation & Topp equation are all expressing the relationship between soil water content and electrical permittivity. However, this method has some limitations; most notably the necessity to determine the velocity from a known depth to a reflecting surface. Therefore, another approach using the frequency dependent attenuation represented by a parameter called Q* was tested and studied in this thesis. The Q* method was evaluated using laboratory measurements, which consists of a series of experiments. A new empirical model was established using experiments where Q* was estimated from measurements on a soil sample with known water contents using two types of antennas (1.6 GHz & 2.3 GHz). Finally, the adaptability of Topp equation and Ferre equation were verified, and a new empirical equation was defined. What’s more, the other method using Q* was proved to be feasible.

Philosophiae Doctor - PhD / Mountainous areas are important water sources in many landscapes. An understanding of how mountainous catchments function is important particularly in semi-arid areas, where water shortages are prevalent. In addition to climate and physiographic factors, the hydrological responses of mountainous catchments can be influenced by land uses and land cover types. Although the general effects of land use and land cover types on hydrological processes are known, prediction of the specific effects in a given catchment is still problematic. This study characterized flowpaths, and hydrological responses to different land cover types in a semi-arid, mountainous Kromme River catchment (Eastern Cape province of South Africa), located in the Cape Fold Mountains of the Table Mountain Group (TMG) geological region.

Philosophiae Doctor - PhD / This thesis aimed at contributing knowledge on how the widespread changes in land use/cover resulting from increasing human population and their associated activities, are influencing hydrological responses in a sub-humid catchment. The study therefore hypothesised that reduced forest cover over time in favour of agricultural activities is altering hydrological processes of the catchment which is affecting the flow characteristics in a sub-humid catchment. The sub-humid catchment selected to investigate these issues is the Nyangores River Catchment in Kenya.

This study evaluated the effectiveness of chiselling and elemental sulfur fertilization in improving an upland and a swale range site with fine loamy, carbonatic, typic calcixeroll soils in the Ait Rbaa Perimeter of central Morocco. Ponding infiltration, soil water content on a mass basis of the 0- to 10-cm and 10- to 20-cm soil layers, peak season biomass production, and botanical composition were monitored during the two growing seasons following the treatments (1984/85 and 1985/86). Chiselling significantly improved infiltration on both sites, although the improvement was greater on the finer and less stony swale site, where chiselling resulted in more stable ridges. The land treatment also increased the average water content by weight of the 0- to 20-cm soil layer. The increase was more frequent on the upland site and most pronounced on its o- to 10-cm surface soil layer. In the chiselled treatments, average soil water content decreased with soil depth on the upland site while it increased on the swale site because of differential furrow stability and soil texture. Both the average infiltration rates of 5 cm of water and the average water content varied with sampling time, although generally in opposite directions. The application of elemental sulfur at the rates of 0, 30, and 60 kg ha-1 did not significantly affect any of the measured variables. Average peak season biomass production was 11% greater with chiselling. Chiselling also positively affected botanical composition on the upland site by depressing average forb proportion and increasing legume ratio in the first growing season. The gain in biomass does not seem to be high enough to strongly recommend chiselling in the Ait Rbaa Perimeter before performing an economic analysis of the operation.

Indiana University-Purdue University Indianapolis (IUPUI) / Non-rainfall waters such as fog and dew are considered as important source of water in drylands, and the knowledge of possible sources of its formation is very important to make future predictions. Prior studies have suggested the presence of radiation fog in drylands; however, its formation mechanism still remains unclear. There have been earlier studies on the effects of fog on soil moisture dynamics and groundwater recharge. On the contrary, no research has yet been conducted to understand the contribution of soil moisture and groundwater to fog formation. This study, therefore, for the first time intends to examine such possibility in a fog-dominated dryland ecosystem, the Namib Desert. The study was conducted at three sites representing two different land forms (sand dunes and gravel plains) in the Namib Desert. This thesis is divided into two parts: the first part examines evidences of fog formation through water vapor movement using field observations, and the second part simulates water vapor transport using HYDRUS-1D model. In the first part of the study, soil moisture, soil temperature and air temperature data were analyzed, and the relationships between these variables were taken as one of the key indicators for the linkage between soil water and fog formation. The analysis showed that increase in soil moisture generally corresponds to similar increase in air or soil temperature near the soil surface, which implied that variation in soil moisture might be the result of water vapor movement (evaporated soil moisture or groundwater) from lower depths to the soil surface. In the second part of the study, surface fluxes of water vapor were simulated using the HYDRUS-1D model to explore whether the available surface flux was sufficient to support fog formation. The actual surface flux and cumulative evaporation obtained from the model showed positive surface fluxes of water vapor. Based on the field observations and the HYDRUS-1D model results, it can be concluded that water vapor from soil layers and groundwater is transported through the vadose zone to the surface and this water vapor likely contributes to the formation of non-rainfall waters in fog-dominated drylands, like the Namib Desert.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13181号 / 論農博第2860号 / 新制||農||1061(附属図書館) / 学位論文||H30||N5103(農学部図書室) / (主査)教授 小杉 緑子, 教授 北山 兼弘, 教授 舟川 晋也 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

No description available.

One of the most important volatiles in magma is water. In magma, water is incorporated in both the melt and in crystals, including hydrous and nominally anhydrous minerals (NAMs). The purpose of this study is to determine the role of magmatic water content in controlling volcano explosivity especially at Merapi volcano, Indonesia, which is one of the most active volcanoes in the world. Here I apply clinopyroxene from two types of eruption products, lava and ash, to test the magmatic water content in the Merapi 2010 eruption. Both oriented and unoriented crystals were analysed using Fourier-Transformed Infrared (FTIR) spectroscopy to establish the clinopyroxene’s crystal water content. By combining the water content of clinopyroxene and geochemical data obtained from EPMA analysis, the magmatic water content is then estimated by inserting the data into the equation of O’Leary et al. (2010) [lnD= -4.2(60.2)16.5(60.5) VI[Al3+]-1.0(60.2) [Ca2+]]. I also investigated clinopyroxene crystals that were experimentally rehydrated, including four oriented crystals from a Merapi 2010 eruption ash sample annealed at a temperature of 700°C and pressure of 1 atm. Magmatic water contents of Merapi 2010 from rehydration experiments were then compared to the Merapi 2006 magmatic water content which were treated under the same conditions. The results revealed a wide variation between samples and among crystals taken from the same sample. However, oriented samples yielded a smaller variation between minimum and maximum clinopyroxene crystal water content and, overall, ash samples yielded higher water content in clinopyroxene than lava samples. The rehydration experiment significantly amplified clinopyroxene crystal water content by 3 to 7-fold compared to the result without the rehydration procedure. Comparison of data between the 2006 and 2010 Merapi eruptions demonstrates that there was a significant difference in magmatic water contents with the 2010 eruption displaying more than twice as much magmatic water than the 2006 eruption. The result implies that magmatic water plays potentially a crucial role in controlling explosivity of Merapi eruptions. / Indonesien är det land i Världen som har den största befolkningen som lever inom 100 km av en aktiv vulkan. Merapi är en av de mest farliga vulkanerna i Indonesien, som också är en av de mest aktiva vulkanerna i Världen och ligger på ön Java runt 15-25 km från Yogyakarta med en total befolkningstäthet på 1000 personer per kvadratkilometer. Utbrott från Merapi har dödat cirka 5000 personer under de senaste 500 åren. Således är det viktigt att studera hur vulkanen beter sig och orsaken till utbrotten för att kunna vita förebyggande åtgärder för att minska antalet dödsfall eller till och med undvika dödsfall helt. Vulkanutbrott kontrolleras av många faktorer, en av faktorerna är flyktiga ämnen i magman och en av de viktigaste flyktiga ämnen är vatten. Det här projektet syftar till att ta reda på vattnets roll på explosiviteten hos utbrotten genom att undersöka eruptiva produkter från utbrotten av Merapi under 2006 och 2010 med hjälp av Fourier-Transformed Infrared (FTIR) spektroskopi. Experimentet använder normalt vattenfria mineraler (NAMs) så som klinopyroxen men vatten kan införlivas i NAMs genom att binda väte i kristallgitteret under kristalltillväxten. Tidigare studier har visat att vattenhalten i klinopyroxenkristall skulle kunna användas för att beräkna magmatisk vattenhalt och därmed jämföra den magmatiska vattenhalt mellan olika utbrott med olika explosivitet i samma vulkan, vilket kan indikera hur vattenhalten påverkar vulkanutbrotten. Magmatiskt vatteninnehåll beräknat utifrån klinopyroxenvattenhalten visade en variation mellan de undersöka proverna från samma utbrott, varför ytterligare undersökning genom rehydreringsexperiment gjordes genom annealing av proverna vid en temperatur av 700 °C och tryck vid 1 atm. Även om det var variation i magmatisk vattenhalt mellan proverna, så har utbrotten av Merapi under 2010 högre magmatiskt vatteninnehåll än utbrottet under 2006 med 3-7 gånger. Sammantaget har Merapi 2010 utbrottet högre explosivitet och högre magmatisk vattenhalt än 2006 utbrottet, vilket innebär att högre vattenhalt ger högre explosivitet. På detta sätt kontrollerade vattnet vulkanens explosivitet för Merapivulkanen.Nyckelord: Merapi vulkan, NA

Forestry has been found to increase the accumulation of methyl mercury (MeHg), a highly neurotoxic compound, in forest soils. However, little is known about how forestry influences catchment processes that governs the mercury (Hg) methylation process. Logging residues are used in harvested catchments in stick roads to reduce soil disturbances caused by forestry machinery. Logging residues left on site after harvest have been suggested to act as a source of high-quality organic matter that stimulates the activity of the microorganisms that carry out the methylation of Hg. In addition, logging residues might influence the activity and abundance of methylating bacteria by reducing the temperature fluctuations in soils below residues and by increasing the soil moisture content. To evaluate the impact of logging residues on the accumulation of MeHg, an experimental field study was carried out in three sites, one in Uppland and two in Västerbotten. The concentration of MeHg was compared between soils covered with residues and soils without residues, and between the lower and upper parts residue piles. Logging residues were not found to influence the levels of MeHg in soils. However, an increased accumulation of MeHg was found in the lower part of residue piles. The accumulation of MeHg in the lower parts was accompanied by a reduced temperature amplitude and an increased water content compared to the upper part of the piles. The increased formation of MeHg might have been mediated by an increased water content in the lower part of the residue piles, possibly by increasing the abundance and activity of Hgmethylating microorganisms due to suboxic/anoxic conditions within biofilms around decomposing needles. The dissolved organic matter composition in soil water differed in soils below residues compared to without residues, but the organic matter signature in soil water under residues was not found to be compliant with an elevated mercury methylation rate. As MeHg accumulated in the lower part of residue piles could become mobilized and transferred to surface water, the suitability of using logging residues in stick roads depends on the location within the catchment. The removal of logging residues could prevent the potential mobilization of MeHg from residue piles. Though, as soil disturbances may cause an increased Hg methylation rate and mediate MeHg export to surface waters, other form of protection, e.g. logging mats, should be used if logging residues are not used to protect soils. / Mänsklig aktivitet har lett till förhöjda halter av kvicksilver (Hg) i atmosfären. Genom långväga transport och deposition har detta orsakat förhöjda halter i svensk natur. Den huvudsakliga exponeringsvägen av Hg för människan sker genom konsumtion av fisk. Halterna av Hg i svensk insjöfisk överstiger EU:s gränsvärden för god kemisk status samt Världshälsoorganisationens riktlinjer för konsumtion i majoriteten av svenska vatten. Ackumuleringen av Hg i biota sker främst i form av metylkvicksilver (MeHg) som är starkt neurotoxiskt. Avverkning av skog tros bidra till en ökad bildning av MeHg i skogsmark genom att skapa miljöer som gynnar etableringen och aktiviteten av de mikroorganismer som omvandlar icke-organiskt kvicksilver (Hg(II)) till organiskt kvicksilver (MeHg). Dessutom kan skogsbruk bidra till en ökad export av MeHg till följd av ändrade hydrologiska förhållanden samt markskador. En ökad bildning av MeHg är oönskad då mobilisering sedermera kan ske till vattendrag där MeHg kan ackumuleras i akvatisk biota. Dock är kunskapen om hur skogsbruk påverkar specifika processer som är av betydelse för metyleringen av Hg begränsad. Inom skogsbruk används avverkningsrester, bestående av till exempel grenar och toppar, i rishögar för att skydda marken mot körskador. Avverkningsrester som lämnas kvar på området efter avverkning tros bidra till en ökad metylering genom att utgöra en källa av högkvalitativt organiskt material vilket kan stimulera bakteriell aktivitet. Dessutom kan avverkningsrester bidra till en ökad metylering av Hg genom att minska temperaturfluktuationerna i mark täckt med ris samt öka markens vattenhalt, vilket kan bidra till en ökad etablering samt att stimulera aktiviteten av Hg-metylerande mikroorganismer. För att utvärdera effekten av avverkningsrester på ackumuleringen av MeHg genomfördes en experimentell fältstudie där koncentrationen av MeHg jämfördes i mark täckt med ris och mark utan ris. Dessutom undersöktes huruvida en ökad metylering kan ske i den nedre delen av riset, vilket skulle kunna möjliggöras av bakterier i biofilmer kring ris under nedbrytning. Koncentrationen MeHg var högre i den nedre delen av rishögarna jämfört med den övre delen. I den nedre delen av riset var temperaturfluktuationerna lägre och vattenhalten högre än i den övre delen av riset. Ackumuleringen av MeHg kan ha skett via biofilmer i de nedre delarna av riset, där tillgången till hög kvalitativt organiskt material samt mer syrefria förhållanden kan ha gynnat etableringen och aktiviteten av de bakterier som utför metyleringen av Hg. Däremot hade typen av marktäcke, dvs mark täckt med ris och mark utan ris, inte någon påverkan på metyleringen av Hg. Karaktären av organiskt material i markvatten skiljde sig mellan typ av marktäcke, men visar inte på att avverkningsrester utgör en källa av högkvalitativt organiskt material. Vattenhalten i mark under rishögar skiljde sig inte jämfört med mark utan ris, men temperaturen var lägre med mindre variation i mark under rishögar. Därmed visar resultatet på att avverkningsrester kan bidra till en ökad bildning av MeHg. En potentiell mobilisering av MeHg som bildats i rishögarna skulle därför kunna bidra till en ökad export av MeHg från avverkade områden. Användningen av avverkningsrester, för att skydda marken vid körning med skogsmaskiner, anses ändå vara fördelaktig för att minimera utläckage av MeHg. Körskador kan skapa stående vattensamlingar där MeHg kan bildas samt kompaktera mark och skapa snabba ytliga flödesvägar i området. Däremot tyder resultatet på att användningen bör ske med hänsyn till att förhindra eventuell transport av MeHg till vattendrag. Ifall avverkningsrester inte används för att motverka markskador bör ett substitut användas, exempelvis stock-mattor, då körskador kan bidra till en ökad metylering och mobilisering av MeHg. Dock saknas kunskap om eventuell mobilisering av MeHg från rishögar till vattendrag och detta bör utvärderas i framtida studier.