Thèses : « Volcanic effects »

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Miles, Georgina. « Detection and effects of volcanic sulphur in the stratosphere ». Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558461.

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Explosive volcanic eruptions perturb the atmosphere, and their main impact arises from the large quantities of 802 emitted. Within this thesis this effect is characterised from a modelling perspective and the detection and measure- ment of 802 by a satellite are improved. A stratospheric aerosol box model is developed that parameterises the aerosol evolution from an emitted mass of volcanic 802. Using aerosol optical depth measurements and a simple energy balance model, the 802 mass is directly related to a global average tempera- ture change. Combining this model with historical eruption records yields a measure of the significance of eruptions based on frequency and magnitude. The model predicts that eruptions of 0.1-1 Mt of 802 are the most significant for perturbing the climate. This is consistent with recent satellite observations of stratospheric optical depth. The model establishes that the radiative forcing from a large volcanic eruption is determined by the mass of 802 erupted, sug- gesting accurate measurement of volcanic 802 is paramount for quantitative monitoring of its atmospheric impact. The brightness temperature difference method developed by Prata et al. (2003) demonstrated the potential for mon- itoring volcanic 802 using the High Resolution Infrared Radiation Sounder 2 (HIR8/2) instruments on the NOAA and MetOp platforms. The Prata method is fast but of limited accuracy. This thesis improves upon this by using an optimal estimation retrieval approach yielding increased accuracy for only moderate computational cost. This is principally achieved by fitting the column water vapour and accounting for its interference in the retrieval of 802. A cloud and aerosol model is used to evaluate the sensitivity of the scheme to the presence of ash and water/ice cloud. This identifies that the cloud or ash above 6 km limits the accuracy of the water vapour fit, increasing the error in the 802 estimate. Cloud top height is also retrieved and this finding quantifies a cloud screening limit that can be imposed. The scheme is applied to a case study event, the 1991 eruption of Cerro Hudson in Chile. A new total erupted mass estimate was found to be 2200 kT ± 600 kT. This fit method yields a minimum mass per unit area detection limit of 3 DU, which is comparable with that for the Total Ozone Mapping 8pectrometer (TOM8), the only other instrument capable of monitoring 802 from 1979-1996. v.

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Haskins, Jessica D. « The effects of volcanic aerosols on mid-latitude ozone recovery ». Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90662.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 30-31).
In this paper, comparisons between the derived Chemistry Climate Model Initiative aerosol data set to balloon sonde measurements of aerosols made in Laramie, Wyoming are made between 1979- 2012. Using the derived CCMI aerosol data set as the input for surface area density of aerosols in the Specified Dynamics-Whole Atmosphere Climate Community Model (SD-WACCM), the impacts of volcanic aerosols on mid-latitude ozone loss are investigated. These results are compared to the ozone column expected recovery from a run of SD-WACCM with no volcanic eruptions in the same period. Particular emphasis is placed on the last decade to investigate how the small volcanic eruptions that have characterized the period of 2008-2012 have impacted the ozone column recovery during this time at northern mid-latitudes as atmospheric chlorine levels decrease from regulation. It is found that the CCMI aerosol data set underestimates aerosol surface area density between the local tropopause and approximately 70mbar in the lower stratosphere. This underestimation is corrected and the resulting change in the ozone column is compared to the initial model output with no volcanic aerosols. Using the correct aerosol values, it is shown that ozone loss in the lower stratosphere after these small, recent volcanoes rivals that of the post-Pinatubo years around 1995-1996.
by Jessica D. Haskins.
S.B.

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Marshall, Lauren Rebecca. « Effects of volcanic eruption source parameters on radiative forcing and sulfate deposition ». Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/22551/.

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Explosive volcanic eruptions can inject sulfur dioxide (SO2) into the stratosphere, which forms stratospheric sulfate aerosol that can significantly impact the climate. The radiative forcing of an eruption depends on several eruption source parameters: the mass of SO2 emitted, the latitude and the emission height. However, the combined effects of these parameters are not well understood. Reconstructions of historic volcanic radiative forcing, which are essential for understanding the role of volcanism on climate variability, are derived from ice core sulfate records, but rely on relationships between ice sheet deposition, stratospheric aerosol burdens and radiative forcing from limited observations. The aim of this thesis is to understand the impact of explosive volcanic eruptions on radiative forcing and volcanic sulfate deposition. The role of individual and combined eruption source parameters are comprehensively investigated using interactive stratospheric aerosol models, perturbed parameter ensembles and statistical emulation. The results demonstrate that radiative forcing is primarily determined by the SO2 emission magnitude, is stronger for tropical eruptions and has a greater dependency on the injection height if the eruption is tropical. The ice sheet deposition is relatively independent of the injection height. The results reveal complex combined effects of the eruption parameters and illustrate the importance of explicitly simulating aerosol microphysical processes to determine aerosol mass, size and lifetime. A wide range of eruption-realisations is found that produce ice sheet deposition that is consistent with ice-core-derived estimates for historic eruptions in the last 2500 years. These eruptions have a range in time-integrated radiative forcing (> ~300 MJ m-2) that is not considered in reconstructions. Sulfate deposition differs considerably between models for the 1815 eruption of Mt. Tambora. The results suggest there is a large uncertainty in radiative forcing derived from ice cores. Consequently, the efficacy of volcanic radiative forcing derived from previous reconstructions may be incorrect.

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Walter, Gary R. « The effects of molecular diffusion on groundwater solute transport through fractured tuff ». Diss., The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_458_sip1_w.pdf&type=application/pdf.

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Zhuo, Zhihong [Verfasser]. « The hydrological effects of explosive volcanic eruptions in the Asian monsoon region / Zhihong Zhuo ». Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1202041981/34.

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Faizy, Shelly Mardhia. « Assessing a Modeling Standard in Volcanic-Geothermal Systems : the Effects of the Lower System Boundary ». Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-438664.

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Geothermal energy consumption is projected to increase along with other renewable energy in the future. Therefore, it is important to have a better understanding on the evolution of geothermal systems to optimize the exploitation of such resources. Generally, numerical models are used as a fundamental tool to study a potential geothermal field. However, current modeling practices tend to focus on the shallow area around the heat source, while ignoring the deeper part below the heat source. The purpose of this project is to observe the influence of lower boundary at the bottom of intrusion towards the evolution of geothermal system, while changing the permeability and topography of host rock systematically, using a software from USGS called HYDROTHERM. Simulations differed in three main aspects: 1) having a layer below, or having the bottom boundary directly below intrusion, 2) different topographies with volcanic significance, and 3) varying permeabilities of the host rock. The study is based on a fossil geothermal system, the Cerro Bayo laccolith in Chachahuén volcanic complex (Neuquén Basin), Argentina. The input parameters were obtained in several ways. ILMAT Geothermometry analysis provide the temperature value related to the intrusion. The whole rock data is used to determined density of the intrusion by calculating partial molar volume of the oxides. The other parameters, e.g. densities of the host rock and the impermeable layer, permeability, porosity, and thermal conductivity were obtained from literature. The result from numerical modeling shows that the bottom boundary below intrusion strongly affect the entire system evolution. The added layer (with constant permeability) has strong influence on the life-span of the system. Additionally, while taking into account on the variation of topography and permeabilities, the models show two temperature anomalies: 1) A caldera volcano’s geometry “traps” heat below the caldera, whereas shield and strato-volcano geometries “push” heat away from below the volcanic edifice, and 2) a low temperature anomaly develops beneath the intrusion in all high permeability models with an added layer. Finally, this assessment could prove to be useful as prior knowledge for optimizing the extraction of heat from a given geothermal field, as well as future investigations towards geological applicability of numerical models of geothermal systems, hydrothermal alteration, and ore formation processes.

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Romine, William Whittington Alan G. « Flow and heat transfer properties of Mono Craters rhyolites effects of temperature, water content, and crystallinity / ». Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/5685.

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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 5, 2009). Thesis advisor: Dr. Alan G. Whittington. Includes bibliographical references.

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Marske, Katharine Ann. « Effects of volcanic ash on the insect food of the Montserrat Oriole Ictereus oberi Lawrence 1880 ». Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/marske/MarskeK0804.pdf.

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The Montserrat Oriole, Icterus oberi Lawrence, endemic to the West Indian island of Montserrat, has grown critically endangered since volcanic eruption began on that island in 1995. The Soufriere Hills Volcano has devastated much of the oriole's native habitat, and populations within intact forests have plummeted in recent years. One hypothesized cause for the Montserrat Oriole's decline is that low insect prey numbers during the nesting season, as a result of volcanic ash in the environment, is resulting in increased nest failure. The hypothesis of a negative effect of ash on canopy arthropods was tested. Four sites, varying in the level of ash deposition they typically receive, were sampled via canopy fogging over a 14-month period. Results indicate that ash is having a significant negative impact on canopy arthropods, particularly at the sampling sites closest to the volcano, but that that the decline is limited to a few insect taxa. To investigate whether the arthropod taxa utilized by the Montserrat Oriole were among those negatively affected by volcanic ash, observational studies were conducted to identify the main insect prey types and sizes brought to oriole nests, and to examine whether nestling feeding rates have declined since the onset of volcanic eruption. Ortoptera, which were not significantly affected by volcanic ash, were the most important nestling food resources utilized in 2002 and 2003. The most frequently delivered size of prey item was calculated at bill length long (approx. 2 cm), and were not significantly affected by ash. Orioles appear to be selecting their prey from the portion of the insect fauna that is least affected by ash in the environment. Oriole nestling feeding rates appear to have declined since 1995, but this may not be strictly due to reduced insect prey numbers. Montserrat's Orthoptera (including Phasmida and Blattaria) were catalogued. Thirty-seven species were reported for the island, including several new species and at least 16 new distribution records for the island.

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Lyu, Han. « EFFECTS OF CLIMATE AND GEOCHEMISTRY ON SECONDARY MINERAL DISTRIBUTION AND SOIL ORGANIC CARBON POOLS IN TROPICAL VOLCANIC REGIONS ». Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263813.

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MINAGAWA, Tetsuo, Takafumi TAKAHASHI, Kazuya TANAKA et Iwao KAWABE. « Evidence for lanthanide tetrad effect in mafic volcanic rocks : Concave tetrad effects in REE patterns for MORB and alkali olivine basalt in western Kyushu, Japan ». Dept. of Earth and Planetary Sciences, Nagoya University, 2008. http://hdl.handle.net/2237/14728.

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Cross-Najafi, Isabella. « Effects of Volcanic Ash Deposition and the Manson Impact on Marine Paleoredox and Paleoproductivity| Geochemical Evidence from the Cretaceous Pierre Shale ». Thesis, West Virginia University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10256866.

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Cretaceous Period. There is limited research on organic carbon content of the Pierre Shale in South Dakota. Frequent volcanic eruptions combined with climate change resulted in an increase in carbon dioxide in the atmosphere, leading to decreases in marine oxygen content. Decreasing marine oxygen has been attributed to higher amounts of preserved organic matter in marine sediment. Impact of volcanic ash deposition in the Cretaceous Interior Seaway has not been thoroughly studied. The Pierre Shale also contains the Crow Creek Member, a 5 foot thick layer of unconsolidated sand and rip-up clasts which may indicate a high-energy depositional event. Some hypothesize that it was deposited by a tsunami generated by the Manson impact. Others believe the Crow Creek Member is evidence of a marine low-stand that occurred before the Bearpaw Cyclothem. It is possible that the depositional event that deposited the Crow Creek Member may have led to increases in organic carbon preservation depending on the burial rates and amount of organic carbon preserved.

To investigate the connection between volcanic ash deposition, the Crow Creek Member deposition, and organic matter preservation of the coastal Cretaceous Interior Seaway, stable isotope geochemistry, trace element geochemistry, and total organic carbon analyses were performed on a 500 foot core drilled near Fort Pierre, South Dakota. Ash beds were identified using X-ray diffraction analysis. Core sampling was driven by location of the Crow Creek Member (above below and within one foot) and by location of ash beds (above below and within one inch), but samples were also taken based on highest and lowest gamma ray values for each five foot (1.52m) core segment. Core sampling was restricted because every other five foot (1.52 meter) section of the Treedam core segement was available for sampling. Statistical T-tests and Z-tests were performed on sample data to determine if there was a significant difference in geochemical signatures between core deposited before and after ash bed deposition and Crow Creek Member deposition. Results and T and Z statistical analyses show no significant changes in stable isotopes nor trace elements as a result of ash bed deposition nor the Crow Creek Member depositional event. Results also indicate that variability of the coastal brackish marine system made any significant trends harder to isolate on such a small scale. Overall δ¹³C_org signatures ( -27 to -26 ‰) indicate that the Cretaceous Interior Seaway was deposited in a brackish shallow marine environment and that there were no drastic changes in sea level throughout the deposition of the Pierre Shale Group that was sampled (Gregory Member up through Virgin Creek Member). The δ

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N data range (-6 to +1 ‰) show that fixed nitrogen was scarce during the deposition of the Pierre Shale and that most of the available marine nitrogen was likely fixed by cyanobacteria.

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Iles, Carley Elizabeth. « Effect of volcanic eruptions on the hydrological cycle ». Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9918.

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Large explosive volcanic eruptions inject SO2 into the stratosphere where it is oxidised to sulphate aerosols which reflect sunlight. This causes a reduction in global temperature and precipitation lasting a few years. Here the robust features of this precipitation response are investigated, using superposed epoch analysis that combines results from multiple eruptions. The precipitation response is first analysed using the climate model HadCM3 compared to two gauge based land precipitation datasets. The analysis is then extended to a large suite of state-of-the art climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). This is the first multi-model study focusing on the precipitation response to volcanoes. The large ensemble allows analysis of a short satellite based dataset which includes ocean coverage. Finally the response of major world rivers to eruptions is examined using historical records. Whilst previous studies focus on the response of just a few rivers or global discharge to single eruptions, here the response of 50 major world rivers is averaged across multiple eruptions. Results are applicable in predicting the precipitation response to future eruptions and to geoengineering schemes that seek to counteract global warming through reducing incoming solar radiation. The main model-simulated features of the precipitation response include a significant global drying over both land and ocean, which is dominated by the wet tropical regions, whilst the dry tropical ocean regions get significantly wetter following eruptions. Monsoon rainfall decreases, whilst in response to individual eruptions the Intertropical Convergence Zone shifts away from the hemisphere with the greater concentration of volcanic aerosols. The ocean precipitation response is longer lived than that over land and correlates with near surface air temperature, whilst the land response correlates with aerosol optical depth and a reduction in land-ocean temperature gradient Many of these modelled features are also seen in observational data, including the decrease in global mean and wet tropical regions precipitation over land and the increase of precipitation over dry tropical ocean regions, all of which are significant in the boreal cold season. The land precipitation response features were robust to choice of dataset. Removing the influence of the El Nino Southern Oscillation (ENSO) reduces the magnitude of the volcanic response, as several recent eruptions coincided with El Nino events. However, results generally remain significant after subtraction of ENSO, at least in the cold season. Over ocean, observed results only match model expectations in the cold season, whilst data are noisy in the warm season. Results are too noisy in both seasons to confirm whether a long ocean precipitation response occurs. Spatial patterns of precipitation response agree well between observational datasets, including a decrease in precipitation over most monsoon regions. A positive North Atlantic Oscillation-like precipitation response can be seen in all datasets in boreal winter, but this is not captured by the models. A detection analysis is performed that builds on previous detection studies by focusing specifically on the influence of volcanoes. The influence of volcanism on precipitation is detectable using all three observational datasets in boreal winter, including for the first time in a dataset with ocean coverage, and marginally detectable in summer. However, the models underestimate the size of the winter response, with the discrepancy originating in the wet tropics. Finally, the number of major rivers that undergo a significant change in discharge following eruptions is slightly higher than expected by chance, including decreased flow in the Amazon, Congo, Nile, Orange, Ob and Yenisey. This proportion increases when only large or less humanly influenced basins are considered. Results are clearer when neighbouring basins are combined that undergo the same sign of CMIP5 simulated precipitation response. In this way a significant reduction in flow is detected for northern South American, central African and less robustly for high-latitude Asian rivers, along with a significant increase for southern South American and SW North American rivers, as expected from the model simulated precipitation response.

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Hill-Butler, C. « Evaluating the effect of large magnitude earthquakes on thermal volcanic activity : a comparative assessment of the parameters and mechanisms that trigger volcanic unrest and eruptions ». Thesis, Coventry University, 2015. http://curve.coventry.ac.uk/open/items/5f612a7d-ebbf-4d38-90aa-89c4984a1c0f/1.

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Volcanic eruptions and unrest have the potential to have large impacts on society causing social, economic and environmental losses. One of the primary goals of volcanological studies is to understand a volcano’s behaviour so that future instances of unrest or impending eruptions can be predicted. Despite this, our ability to predict the onset, location and size of future periods of unrest remains inadequate and one of the main problems in forecasting is associated with the inherent complexity of volcanoes. In practice, most reliable forecasts have employed a probabilistic approach where knowledge of volcanic activity triggers have been incorporated into scenarios to indicate the probability of unrest. The proposed relationship between large earthquakes and volcanic activity may, therefore, indicate an important precursory signal for volcanic activity forecasting. There have been numerous reports of a spatial and temporal link between volcanic activity and high magnitude seismic events and it has been suggested that significantly more periods of volcanic unrest occur in the months and years following an earthquake than expected by chance. Disparities between earthquake-volcano assessments and variability between responding volcanoes, however, has meant that the conditions that influence a volcano’s response to earthquakes have not been determined. Using data from the MODVOLC algorithm, a proxy for volcanic activity, this research examined a globally comparable database of satellite-derived volcanic radiant flux to identify significant changes in volcanic activity following an earthquake. Cases of potentially triggered volcanic activity were then analysed to identify the earthquake and volcano parameters that influence the relationship and evaluate the mechansisms proposed to trigger volcanic activity following an earthquake. At a global scale, this research identified that 57% [8 out of 14] of all large magnitude earthquakes were followed by increases in global volcanic activity. The most significant change in volcanic radiant flux, which demonstrates the potential of large earthquakes to influence volcanic activity at a global scale, occurred between December 2004 and April 2005. During this time, new thermal activity was detected at 10 volcanoes and the total daily volcanic radiant flux doubled within 52 days. Within a regional setting, this research also identified that instances of potentially triggered volcanic activity were statistically different to instances where no triggering was observed. In addition, assessments of earthquake and volcano parameters identified that earthquake fault characteristics increase the probability of triggered volcanic activity and variable response proportions at individual volcanoes and regionally demonstrated the critical role of the state of the volcanic system in determining if a volcano will respond. Despite the identification of these factors, this research was not able to define a model for the prediction of volcanic activity following earthquakes and, alternatively, proposed a process for response. In doing so, this thesis confirmed the potential use of earthquakes as a precursory indicator to volcanic activity and identified the most likely mechanisms that lead to seismically triggered volcanic unrest.

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Walia, Rakesh Kumar. « Effect of horizon roughness on lateral continuity and amplitude variation of deeper reflections ». Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242226.

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Davies, Ceri John. « Assessing the effect of mineral alteration on palaeointensities derived from volcanic rocks of cretaceous age ». Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511065.

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Davidson, Jonathan Robert Joseph. « The Effect of Fractures on Fluid Flow in Geothermal Systems, Taupo Volcanic Zone, New Zealand ». Thesis, University of Canterbury. Department of Geological Sciences, 2014. http://hdl.handle.net/10092/9566.

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The goal of this thesis is to evaluate the effect of fractures on the bulk permeability of rocks. Several methods are used to address this problem: 1) surface radon gas measurements, 2) stress induced fracture permeability 3) fracture generation conditions. Each method was variably effective in providing answer to the initial question. The radioactive radon isotopes (220Rn and 222Rn) were measured in soil gas extracted from 1 m depth in two areas and the concentrations for both isotopes tended to be higher near mapped faults. Soil samples recovered from 1 m depth indicate that the isotopic anomalies are coincident with changes in soil colour and the emanation of 220Rn, but are unrelated to the 222Rn emanation. The lack of a relationship for the latter can be explained by small-scale (~1m) diffusion for >90% of the soil gas measurements. However, diffusion cannot explain all of the observed patterns in the data, and in some specific locations along the fault, 222Rn concentrations are more likely sensitive to advective flow of sub-surface gases, suggesting channelizing of flow along faults. Stress is estimated using Leak-off Tests, estimating overburden weigth, and using drilling induced features observable in boreholes to model stress conditions. The results of the stress interpretation in the Rotokawa Geothermal Field show a relationship between the differential stress and alteration zones containing smectite, where the presence of smectite lowers the differential stress in the crust. This confirms a well-recorded relationship between the friction of rocks, and the strength of the crust. The magnitude of the principal stress axes, which are determined in this thesis, are used to predict the fracture orientations prone to slip in the Rotokawa Reservoir. The precise range of fracture orientations prone to slip is critically dependent on the poorly constrained intermediate stress. However, analysis of stresses on fracture orientations observed in the Rotokawa Andesite, coupled with independent permeability estimates reveal a complex relationship between fracture slip, and permeability, suggesting that slip on fractures can have both a positive or negative effect on slip. This is will depend on the degree of alteration of the Rotokawa Andesite. Failure in the Rotokawa Andesite is a result of: 1) the constant tectonic strain and 2) the increase in fluid pressure. Mathematical models used in this thesis show that if failure occurs through increase in fluid pressure, it is unlikely that the overpressures required to induce rock mass failure are solely generated by porosity/permeability reduction in the Rotokawa geothermal reservoir, requiring a constant external flux of fluids to induce the overpressures. Large-scale failure of the Rotokawa Andesite is modelled as a rock mass using the Hoek-Brown failure criterion, and indicates that the current dominant mode of failure is for the Rotokawa Andesite is shear failure at depth. However, small scale changes in stress, or an increase in rock mass strength will favour tensile failure. High fracture densities observed in three wells of the Rotokawa Andesite are oriented consistent with fractures formed in shear mode, consistent with ‘Healy’ faulting being the main mode of fracture formation in the Rotokawa Andesite.

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Aranzulla, Massimo. « Atmospheric water vapour tomography for DInSAR application and effect of volcanic plume on the microwaves ». Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1543.

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A particular synergy among GPS and SAR techniques, to improve the precision of the current ground deformation monitoring techniques,is investigated. The study of atmospheric anomalies in the GPS EM waves propagation is useful to extrapolate information about the wet refractivity ?eld. Because of its height and the quite variable weather conditions, the estimation of Mount Etna atmospheric anomalies using GPS measurements have noticeable importance to calibrate the SAR interferograms and to establish the effective ground deformation of the volcanic edifice. In this study we presented a method to obtain a 3D electromagnetic waves velocity tomography, starting from the GPS output data analysis. Thanks to the agreement between the University of Catania and the INGV-OE, the GPS data used in this work come from Etnanet framework. The GPS processing has been carried out by using the GAMIT software, by adopting appropriate processing parameters. A new software was developed for deriving the tropospheric tomography from the GPS data. The code was validated by using synthetic tests which assume different structure of atmospheric anomalies and with random noise about twice severe than the typical errors of the GPS. The results of the tests proved that the tomography software is able to reconstruct the simulated anomalies faithfully. The code was applied to study the structure of the atmosphere in an actual case: the period of August 12, 2011 at 10.00 am. The results of the tomography indicate clearly important features of the refractivity field of the studied day. In conclusion, the synthetic tests and the application on actual data sets of the new software demonstrate that it is able to reveal the tropospheric anomalies and thus it is an useful tool to improve the results of the SAR interferometry. An indirect outcome of the use of the GPS for the atmospheric sounding on an active volcanic area is that concerning the detection of volcanic products in the atmosphere. Due to the Mt. Etna persistent activity occurred during the last two years, the capability of GPS to detect the volcanic plume was investigated. The Etna volcano is particularly suited for an in-depth investigation into the aptitude of GPS observations to detect volcanic plumes, owing to both the high frequency of explosive episodes and also the well-developed GPS network. Two di?erent approaches were tested, in order to examine the capability of the GPS network to detect volcanic plumes at Etna. The ?rst approach is applied on the signal strength of the GPS L2 carrier phase data, the second approach, instead, is statistical, and analyzes the single di?erence post ?t residual of elaboration signals to assert the hypothesis that the plume a?ects the GPS data. The proposed method has been tested for the September 4 5, 2007 activity of Mt. Etna. Results from nineteen GPS permanent stations show that during this explosive activity, the GPS residuals definitely include the contribution of the volcanic plume. In the future, data derived from the GPS stations located on Etna's flanks could be used to improve the alerting system of volcanic ash, already operating at the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo.

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Bergström, Marcus. « Explaining Volcanism on Iceland – a review of the Mechanism and Effects of Historic Eruptions ». Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229130.

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Iceland is the land-based expression of the Mid-Atlantic Ridge and is one of the most volcanically active regions of the world. Volcanic eruptions on Iceland are a source of geological hazard to humans and the environment due to the release of ash, gases and lava. The composition of the material released is determined by the chemical composition of the surrounding bedrock and the magma upwelling from the Earth’s crust. The effects of historical eruptions on Iceland have been locally devastating and of global impact. The eruption of Lakagígar in 1783-1784 is known to have been the largest eruption in historical time, and is responsible for the death of ~22 % of theIcelandic population. Skeletal fluorosis is a disease that is sometimes observed following large volcanic eruptions. Volcanic ash can travel great distances in the upper atmosphere and spread over vast areas far away from the erupting volcano. Volcanic ash can change incomposition in the atmosphere, and bring about climate-changing effects. Most notably in recent times, violent ash eruptions can also cause problems to the aviation industry, when ash enters and damages airplane engines. Iceland has many active volcanoes and needs to ensure plans for future eruptions are in place. One such measure is an evacuation plan that protects people living close to an active volcano, such as the most lively on Iceland: Hekla, Katla and Eyjafjallajökull.

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Grove, Clayton. « Direct and indirect effects of flood basalt volcanism on reservoir quality sandstone ». Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10665/.

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This thesis describes the direct diagenetic effects on porous clean sand substrate due to the emplacement of basalt lava flows. The thesis also describes the effects of the emplacement of basaltic dykes and sills into clean porous sandstone. The primary dataset comes from the Cretaceous Etendeka Group, NW Namibia, where the Etendeka Flood Basalts (and associated subsurface plumbing system) interacted with the aeolian Twyfelfontein Formation sandstone. Secondary datasets from the recent Rekjanes Peninsular basalts, Iceland; the Miocene Columbia River Flood Basalt province and the Miocene Snake River Basalts, NW USA are used to constrain the direct effects of lava on substrates in a variety of palaeoenvironmental conditions. The thesis makes use of a number of analytical techniques including: petrography, scanning electron microscopy, image analysis, X-ray diffraction, X-Ray fluorescence, stable isotope spectroscopy (δ18 O and δ13 C) and gas permeability (Hasler and probe). The findings of this work constrain the degree of porosity reduction in clean sandstones due to intrusion emplacement over a complete range of thermal regimes, controlled by the magma flow pathways and duration. The effects range from mild hydrothermal activity and compaction through to intense pyrometamorphism, sediment melting and segregation. Beneath lava flows, the degree of porosity loss is determined by palaeoenvironment (specifically the availability of free water), the lava thickness and the substrate composition. Together the geometries of the igneous components (intrusions and extrusive flows) of the Etendeka Group compartmentalise the sedimentary components (Twyfelfontein Formation), which can be traced due to their effects on hydrothermal activity. The main compartment forming lithologies are vertical-subvertical intrusions, with the lava flows being a minor contributor. The diagenesis during hydrothermal activity was found to be a natural sequestration mechanism of CO2 derived from igneous activity as well as a highly compartmentalised porosity degradation mechanism.

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Shinozaki, Maya. « The effect of sintering and CMAS on the stability of plasma-sprayed zirconia thermal barrier coatings ». Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/244944.

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State of the art thermal barrier coatings (TBCs) for gas turbine applications comprise (7 wt.%) yttria partially stabilized zirconia (7YSZ). 7YSZ offers a range of attractive functional properties – low thermal conductivity, high thermal expansion coefficient and high in-plane strain tolerance. However, as turbine entry temperatures are raised, the performance of 7YSZ coatings will be increasingly affected by sintering and environmental contamination, by calcia-magnesia-alumina-silica (CMAS) deposits. The effect of sintering-induced stiffening on the driving force for spallation of plasma-sprayed (PS) TBCs was investigated. Spallation lifetimes of TBC specimens sprayed onto alumina substrates were measured. A simple fracture mechanics approach was employed in order to deduce a value for the strain energy release rate. The critical strain energy release rate was found to be constant, and if this value had been known beforehand, then the rationale presented here could be used for prediction of coating lifetime. The effect of vermiculite (VM) and volcanic ash (VA) contamination on the sintering-induced spallation lifetime of PS TBCs was also investigated. The presence of both VM and VA was found to accelerate the rise in their Young’s modulus with sintering. Spallation results show that coating lifetime may be significantly reduced, even at relative low addition levels, due to the loss of strain tolerance caused by the penetration of glassy deposits. This result gives a clear insight into the role CMAS plays in destabilizing TBCs. Finally, the adhesion characteristics of ingested volcanic ash were studied using a small jet engine. The effects of engine speed and particle size were investigated. Deposition on turbine surfaces was assessed using a borescope. Deposition mainly occurred on the nozzle guide vane and blade platform. A numerical model was used to predict particle acceleration and heating in flight. It was observed that larger particles are more likely to adhere because they have greater inertia, and thus are more likely to impact surfaces. The temperature of the larger particles at the end of its flight was predicted to be below its softening point. However, since the component surface temperatures are expected to be hotter, adhesion of such particles is probable, by softening/melting straight after impact.

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Thomas, Mark Edward. « Geomechanics of volcano instability and the effects of internally elevated pore fluid (gas) pressures ». Thesis, Kingston University, 2007. http://eprints.kingston.ac.uk/20389/.

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Volcano flank collapse events affect volcanic edifices where a range of different processes are at work. However, there is at least one mechanism of generating instability that may be present at all volcano collapse locations: increases of edifice pore fluid pressures from internal sources. The use of geomechanical classification schemes such as the Rock Mass Rating (RMR) show that a volcano can be considered mechanically weak and little more than a pile of granular material. Initial field work and laboratory testing demonstrated that it is possible to estimate volcanic rock-mass compressive ([sigma][sub]cm), tensile ([sigma][sub]tm) and cohesive (c) strength from the RMR using the power law relationships ([sigma][sub]cm = O.5161e[sup](0.0581*RMR), ([sigma][sub]tm = 0.0055e[sup](0.0744*RMR) and c = 0.0349e[sup](0.0649*RMR) . Simple analogue models using sand piles as scaled proxies for a volcano edifice demonstrate that internal gas pressure is a viable mechanism for promoting structural instability. Complementary two-dimensional limit equilibrium methods (LEM) confirm this effect, showing a clear reduction in edifice stability with increasing degrees of internal pressurisation. However, internal pressures in excess of 25 MPa are needed to reduce the Factor of Safety below unity, indicating this mechanism is unlikely to be the solitary contributor to sector collapse. Three-dimensional numerical modelling of edifice stability using FLAc[sup]3D provides a sophisticated means of undertaking a complex analysis of volcano instability caused by internal pressurisation. Five model geometries were examined over a pressure range of 0 to 20 MPa that allowed the sensitivity of gas pressure on structural stability to be assessed quantitatively. Significant reductions in stability were observed in all cases, with the most unstable modelled edifice possessing a combination of 'weak' foundations and shallow regional gradient. A key finding is that the instability observed in both the analogue and LEM results are replicated in the 3D numerical models, confirming for the first time the significance of internal (gas) pressurisation as a potential trigger mechanism for volcano flank failure.

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Zlotnicki, Jacques. « Sur les effets volcanomagnetiques et tectonomagnetiques ». Paris 7, 1987. http://www.theses.fr/1987PA077296.

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Etude du champ magnetique terrestre sur les edifices volcaniques ou dans les regions soumises a une activite sismotectonique. Trois themes de recherche sont developpes: l'acquisition des mesures de terrain, les mesures experimentales realisees en laboratoire, et les simulations numeriques. L'etude de terrain porte sur des resultats obtenus sur les volcans de la soufriere de guadeloupe, la montagne pelee de martinique et le piton de la fournaise a la reunion

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Durand, Jonathan. « Modélisation de la dynamique et de l'évolution physico-chimique des gaz volcaniques lors de l'éruption d'avril 2007 du Piton de la Fournaise ». Thesis, La Réunion, 2016. http://www.theses.fr/2016LARE0004/document.

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Le dioxyde de soufre (SO2) est un des principaux gaz émis lors des éruptions volcaniques. Au Piton de la Fournaise (La Réunion) environ 230 kT de SO2 ont été libérés pour la seule éruption d'avril 2007. Ces émissions ont provoqué d'importants problèmes sanitaires associés à des dégradations des infrastructures et des écosystèmes. Les mesures de SO2 réalisées par l'ORA ont relevé des concentrations supérieures aux seuils critiques pour la santé mais pas aux périodes où l'éruption était la plus intense. SO2 étude consiste à utiliser le modèle meso-échelle atmosphérique Meso-NH pour simuler le transport de SO2 entre le 2 et le 7 avril, avec une attention portée sur l'influence des flux de chaleur provenant des coulées de lave. Trois domaines sont imbriqués de 2 km à 100m de résolution horizontale. Cette étude de modélisation couple simultanément (i) la dynamique atmosphérique de méso-échelle Meso-NH, (ii) un module de chimie en phase gazeuse et phase aqueuse, et (iii) un modèle de surface simulant une propagation de coulée de lave. Tous les flux (chaleur, vapeur, SO2, CO2 et HCl) sont déclenchés en ligne et sont fonction de la dynamique du front de propagation. Nos simulations reproduisent les observations des concentrations en surface de SO2 pour cette période et diverses analyses de sensibilité montrent que la distribution de soufre a été principalement contrôlée par le flux de chaleur de lave. Les dernières simulations incluent la modélisation du panache de vapeur d'eau lors de l'entrée de la lave en mer. Enfin, deux tests de sensibilités ont été réalisés sur la journée du 5 avril afin d'analyser les interactions dynamiques entre les différentes convections : au cratère et au-dessus de la lave (flux de chaleur sensible) et lors de l'entrée de la lave en mer (flux de chaleur latente)
Sulphur dioxide (SO2) is one of the main gases emitted during volcanic eruptions. The Reunion Island experienced its biggest eruption of Piton de la Fournaise Volcano during April 2007 and this event degassed more than 230 kt of SO2. Theses emissions led to important health issues, accompanied by environmental and infrastructure degradations. SO2 measurements made by the ORA noted higher concentrations than the critical threshold for health but not to periods when the eruption was the most intense. Our study is to use the atmospheric mesoscale model Meso-NH to simulate the transport of SO2 between 2 and 7April, with a focus on the influence of heat flow from lava flows. Three domains are nested from 2km to 100m of horizontal resolution. This modeling study torque simultaneously (i) atmospheric dynamics of mesoscale Meso-NH, (ii) a chemistry module in the gas phase and aqueous phase, and (iii) a surface model simulating a lava flow spread. All flow (heat,vapor, SO2, CO2 and HCl) are triggered online and are function of the dynamics of thepropagation front. Our simulations reproduce the observations of surface concentrations of SO2 for that period and various sensitivity analyzes show that the sulfur distribution was mainly controlled by the lava heat flow. The latest simulations include the modeling of the Laze plume when the lava meet the sea. Finally, two sensitivity tests were performed on the day of April 5 to analyze the dynamic interactions between convections: the crater andover the lava (sensible heat flux) and at the entry of lava into the sea (latent heat flux)

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Kushnir, Alexandra Roma Larisa. « Permeability development and evolution in volcanic systems : insights from nature and laboratory experiments ». Thesis, Orléans, 2016. http://www.theses.fr/2016ORLE2006/document.

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La transition entre le comportement effusif et explosif des volcans de magma riche en silice est en partie contrôlée par la capacité des surpressions gazeuses à se dissiper hors du magma. La libération efficace des gaz est associée aux éruptions effusives tandis que la rétention de ces gaz contribue aux processus explosifs. L’une des approches pour évaluer la facilité d’échappement des gaz est de considérer l’évolution et le développement de la perméabilité dans la colonne magmatique et dans l'édifice. J'évalue dans ce travail de thèse le rôle des changements post-mise en place sur la microstructure dans des andésites basaltiques du Merapi (Indonésie). La perméabilité de ces roches est principalement contrôlée par des fissures liées à leur mise en place. Malgré l’influence importante de ces fissures post-mise en place pour dégazer à travers l'édifice, elles ne contribuent pas au dégazage intrinsique du magma en cours d’ascension. Pour s’affranchir de l'influence des microstructures post-mise en place du magma, j'étudie le développement et l'évolution in situ des réseaux perméables en déformant des magmas à deux phases (bulles de gaz et liquide silicaté) en cisaillement simple dans une presse Paterson selon des viscosités et des vitesses de déformation réalistes pour la partie haute des conduits des strato-volcans. Le développement de la perméabilité est confirmé in situ et se développe à des vitesses de déformation supérieures à 4,5 x 10⁻⁴ s⁻¹. À des vitesses de déformation élevées (> 5 x 10⁻⁴ s⁻¹) le magma est fragile et l’échappement du gaz est lente, facilitée par l'interconnexion de courtes fractures de Mode I. À des vitesses de déformation < 5 × 10⁻⁴ s⁻¹, le magma se comporte à la fois de manière fragile et visqueuse et la perméabilité se développe lorsque la déformation est importante; le gaz s’échappe rapidement par de longues fractures de Mode I bien développées. Les fractures de Mode I sont idéalement orientées pour le dégazage du conduit central et sont, surtout, soumises à peu de déformation jusqu'à ce qu'elles soient réorientées dans la direction de cisaillement. Ces caractéristiques de dégazage peuvent, à long terme, favoriser un dynamisme éruptif effussif
The transition from effusive to explosive behaviour at silicic volcanoes is, in part, governed by how efficiently gas overpressures are dissipated from the volcanic plumbing. Efficient gas release is associated with effusive eruptions while inadequate outgassing contributes to explosive processes. One approach to assessing the facility of gas escape is by considering how permeability develops and evolves in the magma column and surrounding edifice. Here, I appraise the role of post-emplacement changes to microstructure in edifice-forming basaltic andesites from Merapi (Indonesia). The permeability of these rocks is dominantly crack-controlled and while these features exert important controls on gas escape through the edifice, they do not represent the escape pathways available to gas within ascending magma. To avoid the influence of postemplacement microstructure, I investigate the development and evolution of permeable networks in magmas by deforming initially impermeable two-phase magmas in simple shear. This is done in a Paterson apparatus at viscosities and shear strain rates appropriate to upper conduits in stratovolcanoes. Permeability development is confirmed in situ and develops at moderate to high shear strain rates (> 4.5 × 10⁻⁴ s⁻¹). At very high strain rates (> 5 × 10⁻⁴ s⁻¹) the magma behaves in a brittle manner and gas egress is slow, facilitated by the interconnection of short, Mode I fractures. At moderate shear strain rates (< 5 × 10⁻⁴ s⁻¹), the magma displays both brittle and viscous behaviour and permeability develops at high strain; gas escape is rapid owing to long, well-developed, sample-length Mode I fractures. Mode I fractures are ideally oriented for outgassing of the central conduit and, critically, accommodate little deformation until they are rotated into the direction of shear, making them long-lived outgassing features that may favour volcanic effusion

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Williams, Trevor David. « Surviving Catastrophe : Resource Allocation and Plant Interactions Among the Mosses of Mount St. Helens Volcano ». PDXScholar, 2016. https://pdxscholar.library.pdx.edu/open_access_etds/3373.

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Mosses are some of the first colonizers to disturbed sites, yet their roles in early plant community structuring are not well understood. The primary succession zones of volcanoes provide opportunities to conduct natural experiments into how mosses contribute to early plant community formation, as well as how the unique environments found in such zones affect plant traits, particularly those associated with stress tolerance. Though plant community changes have been well-documented since Mount St. Helens (MSH) volcano erupted in 1980, the volcano's moss assemblages, their influence on other plants, and their potential roles in chemical-mediated competition and biogeochemical cycling have garnered little attention. Using a natural stress gradient from primary to secondary succession zones on MSH, and in control and nutrient manipulated test plots, I sought to elucidate how populations of three dominant moss species, Polytrichum juniperinum, Ceratodon purpureus, and Racomitrium canescens, respond to abiotic stress, as well as to provide life history and interaction data on establishment stages of these stress tolerant taxa. I first analyzed possible tradeoffs in survival strategies of four moss communities in test plots along an abiotic stress gradient. In P. juniperinum, seta specific density (mg/mm) increased significantly in response to nitrogen (N) addition. Differences in both vegetative and sexual reproductive morphological measurements were dependent on site and did not correlate with abiotic stress. In C. purpureus, the percentage of total spores germinated increased with N addition. Site dependent responses in nutrient allocation to vegetative and reproductive structures may be a result of phenotypic plasticity alone or may be a result of local adaptation. In mosses adapted to environmental stress, the allocation of nitrogen must be balanced between growth and survival. Efficient nitrogen uptake confers a competitive advantage if allocated to the higher dispersal of quickly germinating spores. Second, my results show the moss R. canescens may be able to inhibit the germination rate of co-occurring moss spores when spores were germinated in moss gametophyte infusions. R. canescens may also inhibit the germination of the co-occurring vascular plant Lupinus lepidus when seeds are germinated within intact moss patches. By uncovering chemical-mediated interactions between mosses on the germination and initial growth of neighboring mosses and vascular plants we can gain a better understanding of the mechanisms stress tolerant plants may use to limit resource competition. Such advantages offer insight into how mosses effectively colonize and affect primary succession landscapes.

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Merlhiot, Gaëtan. « Perception des risques, incertitude et prise de décision en situation de catastrophe naturelle liée au volcanisme ». Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF20019.

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L’objectif général de cette thèse est d’étudier la prise de décision des individus en situation de catastrophe naturelle, en l’occurrence d’origine volcanique, et d’aboutir à des applications possibles, notamment à une amélioration de la prise de décision des populations exposées. Nous nous sommes intéressés à l’incertitude, dimension essentielle des situations de catastrophe naturelle, qui présente un impact important sur les émotions et la prise de décision des individus. D’une part, l’incertitude situationnelle est déterminante quant aux émotions prospectives comme la peur, et, d’autre part, l’incertitude des conséquences influence l’utilisation des heuristiques émotionnelles (émotions comme éléments pertinents à la décision) dans la prise de décision (système 1). Ce travail de thèse a été traité selon trois axes complémentaires. Dans le premier axe, intitulé Incertitude situationnelle, effet de cadrage et prise de décision, nous avons montré que la simple exposition à l’incertitude situationnelle impliquerait une absence d’effet de cadrage, qui, selon les travaux précédents, pourrait provenir d’une augmentation du traitement systématique (système 2), liée au processus de régulation fronto-amygdalienne. Dans le second axe, Incertitude des conséquences, information à la population et prise de décision, nous avons mis en évidence le fait qu’une réduction de l’incertitude des conséquences dans l’information donnée à la population permettait, dans certains cas précis, d’aboutir à de meilleures prises de décision. L’effet obtenu n’a néanmoins été identifié que dans les situations impliquant de fortes émotions anticipatoires (domicile, dilemmes moraux), situations fréquentes au cours des catastrophes naturelles. Enfin, dans le troisième axe, Création d’une base de stimuli pour l’étude du comportement humain face aux risques naturels, nous avons présenté la construction et la validation d’une base d’images liées aux catastrophes naturelles et au volcanisme, nommée « Natural Disasters Picture System » (NDPS)
The overall aim of this thesis is to examine the decision-making of individuals at risk of natural disaster, specifically related to volcanism, and to achieve potential applications, notably to improve the decision-making of individuals at risk. We focused on the uncertainty, an essential aspect of natural disaster events, which greatly impacts individuals’ emotions and decision-making. On the one hand, the situational uncertainty is an essential component for prospective emotions such as fear, and on the other hand, the uncertainty of consequences determines the use of affect heuristics (emotions used as relevant aspects of the decision) in decision-making (system 1). This doctoral thesis followed three complementary axes. In the first axis, namely Situational Uncertainty, Framing Effect and Decision-Making, we exhibited that the mere exposure to situational uncertainty could negate the framing effect, which could be explained, based on previous works, by an increase of systematic processing (system 2), stemming from the processes of the fronto-amygdala regulation. In the second axis, Uncertainty of Consequences, Information to Population and Decision-Making, we have evidenced that a reduction of the uncertainty of consequences applied to the information to population could improve, under certain circumstances, the individuals’ decisions. This effect was only identified in situations of highly charged anticipatory emotions (home environment, moral dilemmas), which are frequently encountered situations during natural disasters. Lastly, in the third axis, Creation of a Stimuli Dataset for the Study of the Human Behavior Facing Natural Hazard, we detailed the conception and validation of an image dataset dedicated to natural disasters and volcanism, named “Natural Disasters Picture System” (NDPS)

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Aloupogiannis, Panagiotis. « Etude theorique et experimentale des effets de matrice en analyse par emission de rayons x induite par particules chargees (pixe) : etablissement d'une nouvelle methode de correction dite des "parametres alpha" ». Paris 7, 1988. http://www.theses.fr/1988PA077002.

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Mora, Fernandez Mauricio Manuel. « Étude de la structure superficielle et de l'activité sismique du volcan Arenal, Costa Rica ». Chambéry, 2003. http://www.theses.fr/2003CHAMS004.

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Le volcan Arenal présente une activité explosive continue de type strombolien caractérisée par l'effusion permanente de coulées de lave, la formation d'écoulements pyroclastiques et une sismicité intense. Cette activité est suivie depuis 1974 par l'Observatorio Sismologico y Vulcanologico de Arenal y Miravalles (OSIVAM) rattaché à l'Institut Costarisien d'Electricité (ICE). Dans la première partie de ce travail, nous avons étudié l'activité volcanique de l'Arenal entre 1986 et 2000 à partir des données obtenues par l'OSIVAM que nous avons regroupées en une base de données unique. Nous avons analysé ces informations en nous focalisant sur le comportement du volcan à l'échelle de plusieurs années. Il est actuellement difficile d'établir si les évolutions des paramètres observés reflètent de réelles modifications de l'activité éruptive de l'Arenal. Nous avons mis en évidence les limites du système de surveillance et nous porposons des améliorations. La suite de ce mémoire est une étude de la structure de l'activité sismique réalisée à l'aide de plusieurs réseaux denses de capteurs (triangles, demi-cercles, profils, réseaux en L). A partir des données de deux profils sismiques déployés à l'Est et l'Ouest du volcan, nous avons analysé les effets de la structure sur les signaux sismo-volcaniques. De fortes variations de l'amplitude des pics spectraux sont observées localement le long des profils. Nous avons étudié ces anomalies en utilisant la méthode des rapports spectraux U/V et avons montré que la forme de ces rapports est indépendante du type de signal utilisé. Les résultats mettent en évidence dans certains sites des effets de résonance à des fréquences qui correspondent à celles des amplifications observées. Des fonctions de transfert théoriques des ondes S ont été calculées en chaque site en utilisant des modèles de vitesse obtenus par sismique réfraction. Lorsqu'il existe un contraste d'impédance suffisant entre les couches peu consolidées et les couches plus profondes les rapports spectraux et les fonctions de transfert présentent des pics de même fréquence. Cela montre le lien entre les amplifications observées et la structure géologique. Nous avons également sondé la structure superficielle de l'Arenal en utilisant la méthode d'auto-corrélation spatiale basée sur le calcul de coefficient de corrélation entre station de réseaux semi-circulaires. Nous avons amélioré l'inversion de ces coefficients pour mieux estimer les vitesses de phase des ondes de surface. A l'ouest du volcan, les vitesses des ondes de Rayleigh varient de 765 m s-1 à 1 Hz à 300 m s-1 à 12 Hz et pour les ondes de Love entre 780 et 295 m-1 dans la même bande de fréquence. A l'est, les vitesses des ondes de Raleigh sont comprises entre 1386 et 300 m s-1 et celle de Love entre 1983 et 315 m s-1. Ces courbes de dispersion ont ensuite été inversées pour obtenir des modèles de structure, en tenant compte des connaissances géologiques disponibles. Les modèles de vitesse obtenus sont cohérents avec les résultats de sismique réfraction et les calculs de rapports spectraux. L 'analyse d'enregistrements continus large bande montre une grande variété de comportement du trémor et des explosions volcaniques. Les résultats révèlent notamment l'existence de deux processus de résonance non stationnaires pouvant se produire simultanément mais ayant des caractéristiques spectrales différentes. Cela suggère qu'à certains moments, deux sources de trémor peuvent être actives. Les méthodes auto-régressives utilisées fournissent des mesures robustes et de haute résolution fréquentielle et temporelle de la fréquence des pics spectraux. Elles montrent également que les fréquences et les facteurs de qualité de ces pics varient rapidement au cours du temps, reflétant des évolutions des propriétés physiques des sources sismo-volcaniques
Arenal volcano presents a continuous strombolian explosive activity characterized by permanent lava flows, sporadic pyroclastic flows and intense seismic activity. This activity is monitored since 1974 by the "Observatorio Sismologico y Volcanologico de Arenal y Miravellas (OSIVAM)" of the Instituto Costarricence de Electricidad. In the first part of this work we study the volcanic activity between 1984 to 2000 using data obtained by OSIVAM that we grouped in a unique database. Data were analysed focusing on the volcano's behavior at the time scale of several years. So far it is difficult to establish whether the observed variations of different parameters represent real changes in volcanic activity or not. We highlight limitations of volcanic monitoring system and proposed improvements. The next part of this work consists in a study of the volcanic structure and seismic activity using different dense array data (triangles, semi-circles, profiles, L-array)

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Clarke, Dawn Elizabeth. « Silencing the voices of women : a case study on the effects of the "Supporting People" programme on survivors of domestic abuse in a support and housing association ». Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/4342.

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For centuries women have experienced domestic violence from men they know, as a consequence of which many turn to public services for support. Traditionally, these services have failed to provide adequate support, yet it is through these interactions with the services that abused women's lives are shaped and defined. Service providers therefore need to hear their voices in order to develop effective support services that enable survivors to 'move on' with their lives. A government initiative ¬- the Supporting People Programme (SPP) - has the potential to ensure that housing support providers develop their services in this manner. The main aim of the SPP is to place service users at the 'heart' of the system through user participation. Whilst this is certainly a step in the right direction, my concern is whether this actually happens or whether services adopt a tokenistic approach to user participation that marginalises and silences women survivors. My primary research question, therefore, is: 'What is the impact of the SPP on women survivors of domestic abuse?' Using a research design that included document analysis, observation and semi-structured interviews, I argue that the SPP has the potential to improve the lives of survivors and even to ameliorate, if not eradicate, domestic abuse. However, far from achieving this, the SPP through lack of commitment to ensuring that services actually meet the funding requirement of user participation continues to marginalise and silence the voices of women survivors.

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Clarke, Dawn E. « Silencing the voices of women. A case study on the effects of the "Supporting People" programme on survivors of domestic abuse in a support and housing association ». Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/4342.

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For centuries women have experienced domestic violence from men they know, as a consequence of which many turn to public services for support. Traditionally, these services have failed to provide adequate support, yet it is through these interactions with the services that abused women's lives are shaped and defined. Service providers therefore need to hear their voices in order to develop effective support services that enable survivors to 'move on' with their lives. A government initiative ¬- the Supporting People Programme (SPP) - has the potential to ensure that housing support providers develop their services in this manner. The main aim of the SPP is to place service users at the 'heart' of the system through user participation. Whilst this is certainly a step in the right direction, my concern is whether this actually happens or whether services adopt a tokenistic approach to user participation that marginalises and silences women survivors. My primary research question, therefore, is: 'What is the impact of the SPP on women survivors of domestic abuse?¿ Using a research design that included document analysis, observation and semi-structured interviews, I argue that the SPP has the potential to improve the lives of survivors and even to ameliorate, if not eradicate, domestic abuse. However, far from achieving this, the SPP through lack of commitment to ensuring that services actually meet the funding requirement of user participation continues to marginalise and silence the voices of women survivors.

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Foucart, Brice. « Observation et modélisation de la Formation de Nouvelles Particules (FNP) au sein du panache volcanique du Piton de la Fournaise ». Thesis, La Réunion, 2019. http://www.theses.fr/2019LARE0014/document.

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L'activité volcanique peut représenter une source naturelle de pollution atmosphérique. Cette pollution peut engendrer une dégradation de la qualité de l'air, affecter la santé humaine et perturber la sécurité aérienne. Le Piton de la Fournaise à La Réunion est l'un des volcans basaltique les plus actifs au monde. Ses éruptions sporadiques génèrent des panaches volcaniques essentiellement constitués de gaz et de nanoparticules qui se propagent dans l'atmosphère. En journée, la formation d'oxydants (photolyse) permet d'oxyder une partie du dioxyde de soufre en acide sulfurique. Les molécules d'H2SO4 peuvent réagir avec les molécules d'eau atmosphérique pour former des embryons via la nucléation binaire homogène. Puis, ces embryons grossissent grâce aux processus de condensation et/ou coagulation conduisant alors à la formation d'un aérosol volcanique submicronique. Cette thèse vise à observer, comprendre et modéliser les processus de Formation de Nouvelles Particules (FNP) au sein des panaches volcaniques. De ce fait, elle s'organise en deux parties. La première se base sur les données recueillies lors de la campagne multidisciplinaire STRAP menée à l’observatoire du Maïdo et au Piton de la Fournaise en 2015. Elle expose les résultats issus d’une double analyse de la fréquence et de l’intensité des événements de FNP à l’observatoire. Tandis que la première analyse s’intéresse aux processus en l’absence du panache volcanique, la seconde met en exergue les spécificités de la FNP liées à sa présence au Maïdo. La seconde partie s'axe autour de la modélisation d'abord 0D puis 3D des processus de FNP au sein des panaches volcaniques via le modèle atmosphérique Méso-NH
Volcanic activity can be a natural source of air pollution. This pollution can lead to a deterioration in air quality, affect human health and disrupt aviation safety. The Piton de la Fournaise in Reunion Island is one of the most active basaltic volcanoes in the world. Its sporadic eruptions generate volcanic plumes consisting mainly of gases and nanoparticles that spread in the atmosphere. During the day, a part of the sulphur dioxide can be oxidized to sulphuric acid thanks to oxidants production (photolysis). H2SO4molecules tend to react with atmospheric water molecules and form clusters via homogeneous binary nucleation. Then, these clusters grow by condensation and/or coagulation processes leading to the formation of a submicronic volcanic aerosol. This thesis aims to observe, understand and model the New Particle Formation (NPF) processes within volcanic plumes. Consequently, it is organized in two parts. The first is based on the data gathered during the multidisciplinary STRAP campaign conducted at both the Maïdo Observatory and Piton de la Fournaise volcano in 2015. It presents the results from a dual analysis of the NPF events frequency and intensity at the observatory. While the first analysis focuses on processes in the absence of the volcanic plume, the second highlights the specificities of the NPF related to the presence of the plume at Maïdo. The second part focuses on 0D then 3D NPF processes modelling within volcanic plumes via the Meso-NH atmospheric model

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Michel, Sylvie. « Effets électriques et magnétiques sur le Piton de la Fournaise (île de La Réunion) : influence des circulations des fluides ». Paris 7, 1995. http://www.theses.fr/1995PA077057.

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Localisé sur l'île de la Réunion, le Piton de la Fournaise est l'un des volcans basaltiques les plus actifs au monde. Aux signaux volcanomagnétiques engendrés par les éruptions, s'ajoutent des variations magnétiques plus inhabituelles. En certains points du volcan, apparaissent de lentes variations, irréversibles sur 9 ans, et des variations cycliques annuelles, distinctes de la variation magnétique annuelle ionosphérique. Dans cette thèse nous nous intéresserons uniquement aux variations magnétiques à long terme. Les lentes variations sont corrélées à l'activité globale de la Fournaise, tandis que les ondes annuelles évoluent au rythme des modulations saisonnières de la température atmosphérique et de la pluviosité, totalement indépendantes de l'activité éruptive. Centrée sur l'axe principal, l'amplitude des ondes annuelles est maximale sur le cône. Sur ce massif fortement fracturé et soumis à une forte pluviosité, les mécanismes envisagés pour interpréter les variations volcanomagnétiques sont basés sur les circulations des fluides et leurs perturbations sous l'effet des variations du champ de contraintes et des modulations saisonnières de paramètres climatiques. Pour argumenter cette hypothèse, une cartographie de polarisation spontanée (ps) a été réalisée en 1992. Elle montre d'intenses anomalies ps centrées sur le cône et sur l'axe principal de fractures. Cette cartographie confirme l'existence de circulations hydrothermales à l'aplomb du cône et le long de l'axe principal de fractures où l'amplitude des ondes annuelles est maximale. La comparaison des cartographies de 1981 et 1992 montre que la géométrie du système hydrothermal a évolué en moins de dix ans. Des variations temporaires de ps ont aussi été observées lors de l'éruption du 27 août 1992. L'amplitude de ces potentiels ps et leur variabilité temporelle confortent l'hypothèse d'effets électrocinétiques à l'origine des variations volcanomagnétiques observées sur la Fournaise. D'autre part, cette étude ps a également révélé l'existence d'une structure ancienne régionale à l'aplomb du volcan, orientée n 120, qui interagit sur son dynamisme éruptif actuel. (Doc Thèses)

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Dumont, Marc. « Caractérisation multi-échelle des structures hydrogéologiques en contexte volcanique insulaire par électromagnétisme héliporté : application à l’île de La Réunion ». Thesis, La Réunion, 2018. http://www.theses.fr/2018LARE0010/document.

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L’île de La Réunion a été couverte par une vaste campagne de géophysique héliportée en 2014. Le dispositif SkyTEM a permis de cartographier l’anomalie du champ magnétique et la résistivité électrique du sous-sol jusqu’à 300 m de profondeur, et ce, sur l’ensemble de l’île. L’acquisition de ce jeu de données met en évidence la problématique de l’interprétation des données électromagnétiques héliportées à l’échelle régionale. L’interprétation d’un modèle 3D de résistivité d’une superficie 2 500 km2 nécessite la mise en place de méthodologies innovantes pour le confronter aux données géologiques, climatiques et hydrogéologiques. L’objectif de la thèse est de valoriser ce jeu de données géophysique à l’échelle régionale en intégrant l’analyse hydrogéologique à différentes échelles spatiales. Pour répondre à ces problématiques, cette thèse s’organise autour d’une méthodologie hydrogéophysique multi-échelle qui permet d’étudier la répartition et le fonctionnement des aquifères à des échelles inédites jusqu’alors. Pour interpréter les 350 000 sondages électromagnétiques de la campagne, une approche statistique a été développée pour synthétiser une information sur les contrastes 3D en 2D. Les résultats, cohérents avec les connaissances géologiques et hydrogéologiques de l’île, ont permis d’analyser l’impact des paramètres géologiques et climatiques régionaux sur la répartition des aquifères et les processus d’altération. Sur le littoral, les données de résistivité sont confrontées à des logs de conductivité électrique de l’eau souterraine afin de valider l’interprétation de la géophysique. Le modèle de résistivité permet ainsi de cartographier et d’analyser les paramètres de contrôle du phénomène d’intrusion saline à l’échelle de l’île. En altitude, l’utilisation conjointe des données électromagnétiques et magnétiques héliportées permet de caractériser la géométrie des structures géologiques et d’imager les profils et paléo-profils d’altération météorique
In 2014, Reunion Island was covered by a vast airborne geophysics campaign. The SkyTEM device mapped magnetic anomalies and bulk resistivity at an extra 300 m depth throughout the island. The resulting dataset revealed the issue of interpreting airborne electromagnetic data at the regional scale. The interpretation of a 3D resistivity model wrapping 2 500 km2 requires the implementation of innovative methodologies to compare it with geological, climatic and hydrogeological data. The aim of the thesis is to enhance this geophysical dataset at the regional scale by integrating hydrogeological analysis at different spatial scales. To answer these issues, this thesis revolves around a multi-scale hydrogeophysical methodology, which allows to analyze how aquifers are distributed and their behaviors on unprecedented scales. A statistical approach has been developed to synthesize 3D geo-electrical contrasts in 2D to interpret the 350 000 soundings. All outcomes are consistent with the geological and hydrogeological knowledge of the island, enabling us to study how regional geological and climatic parameters impact the distribution of aquifers and weathering processes. In the coastal zone, resistivity data are compared with groundwater electrical conductivity logs to validate the interpretation of geophysics. Thus, the resistivity model helped mapping saltwater intrusion and analyzing its control parameters at the island scale. Inland, the combined use of airborne electromagnetic and magnetic data made it possible to characterize the geometry of geological structures and to image weathering profiles and paleo-profiles. Combining results gathered on various scales allows the analysis of weathering impact on aquifers of shield volcanoes. On the coastal zone, un-weathered and highly permeable lithological units (up to 10-1 m/s) are subject to saltwater intrusion, even with recharge rates up to 6 to 8 m per year. With decreasing transmissivity, aquifers become less exposed to saltwater intrusion. According to geophysics outcomes, the contacts between different eruptive phase products at high altitude are characterized by specific weathering paleo-profiles which create permeability contrasts conducive to perched aquifers establishment. Examining the geophysical response in different areas of the island made it possible to analyze the dynamics of weathering processes, initially controlled by the age of the formations and secondly, by the rainfall rates and the temperature. These results showed that weathering and structure of basaltic volcanoes depend on their age and on windward/leeward slopes. Thus, our research helped improve the accuracy of the conceptual hydrogeological model including geological structuring and time evolution of basaltic volcanic aquifers in an insular environment

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Martelli, Kim. « Vulnérabilité physique des milieux urbanisés face à la menace des inondations (lahars et crues éclair) : application au cas d'étude d'Arequipa au Pérou ». Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00881754.

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Les écoulements volcaniques (lahars, écoulements hyperconcentrés) et les crues soudaines représentent des phénomènes destructeurs et dangereux. Malgré leur pouvoir destructeur (e.g. Armero, Colombie, 1985), il existe très peu d'études centrées sur les effets des lahars en zone urbaine, alors qu'ils représentent une menace réelle pour de nombreuses villes, comme Arequipa, au Pérou. Arequipa est une ville de presque 1 million d'habitants située à 17 km au sud-est du volcan El Misti. La dernière éruption majeure du Misti remonte à 550 ans (1460 après J.C.) et de plus petites éruptions ont parsemé le 18ème et le 19ème siècle. Des lahars dont les volumes sont compris entre 0,01x106 et 11x106 m3 se sont formés et des inondations ont balayé les vallées tous les 5 à 10 ans. Suite à l'augmentation de la population d'Arequipa, la zone urbanisée s'étend maintenant sur les flancs du volcan, jusqu'à 9 km du sommet. En réponse à cette croissance rapide et apparemment incontrôlée, il est essentiel d'évaluer l'utilisation des sols, les bâtiments et les infrastructures en fonction de leur vulnérabilité. Des scénarios d'aléas ont été développés à partir d'anciennes et d'actuelles études géologiques, de cartes traditionnelles et des modèles numériques (tels que Titan2D) des dépôts volcaniques et fluviaux, d'études de terrain sur l'utilisation des sols, le type de bâtiments et d'infrastructures, d'analyses statistiques (y compris des analyses multi variantes) et enfin des caractéristiques géotechniques des matériaux utilisés pour les constructions. Trois scénarios de référence ont été utilisés allant d'un scénario de crue (récurrence de 5 à 10 ans) à une éruption (sub) Plinienne (VEI >3, récurrence de 5000 à 20 000 ans). Les zones inondables ont été délimitées en utilisant des résultats de code de simulation couplés à des cartographies géologiques et à des analyses de magnitude/fréquence. L'amélioration d'un MNT, construit à partir d'études DGPS et de données ASTER (10 m de résolution), a permis de modéliser les écoulements à partir de Titan2D. Les résultats du modèle montrent une extension des écoulements plus longue que celles proposées dans les études précédentes (e.g Vargas et al, 2010). L'étude de terrain a permis de classifier l'utilisation des sols selon 19 catégories et les principaux bâtiments et infrastructures selon 10 catégories. Par exemple, les bâtiments ont été classés et ordonnés selon des critères de nature du matériau principal les constituant, nombre d'étages, etc. De la même manière, la classification de l'utilisation des sols et du type d'infrastructures ont été classé en fonction de différents éléments comme le taux d'occupation, l'importance des évacuations d'urgence etc. Les effets mécaniques des écoulements sur les immeubles et les infrastructures ont été recherchés dans le but d'élaborer des fonctions de vulnérabilité. Cette étude a révélé que les bâtiments et l'utilisation des sols du Quebrada Huarangal sont particulièrement vulnérables et exposés au risque même lors d'un écoulement de faible magnitude. Ceci est essentiellement dû à la très faible qualité des constructions dans les zones à hauts risques du Quebrada Huarangal. Au contraire, le risque présent dans la vallée du Rio Chili est une zone à faible risque. Le niveau de risque inhérent au système d'énergie hydroélectrique et aux réserves d'eau potable reste inquiétant pour la ville, notamment durant une crise volcanique. Cette étude a mis en évidence les capacités d'intégration des données SIG générant de l'information sur le risque via la combinaison de scénarios d'aléas et d'éléments de vulnérabilité. Ces méthodes semblent être prometteuses pour l'étude et la prévention des risques volcaniques. De plus, une base de données mise à jour pourrait aider à gérer de manière efficace une possible crise volcanique en temps réel, et ce qui est plus important encore, assister les tâches de réduction des risques.

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Pei, Ling Kai, et 裴令凱. « Atmospheric and Ionospheric Effects Triggered by Volcanic Eruptions ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/90195655010665873181.

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碩士
國立中央大學
太空科學研究所
100
Volcanic activity plays an important role on weather/climate and atmosphere-ionosphere coupling. Volcanic eruptions can disturb atmospheric temperature and ionospheric electron density. FOMORSAT-3/COSMIC (F3/C) observations and ECMWF data are uesd to probe atmospheric temperature changes during 8 great volcanoes of Volcanic Exlosivity Index (VEI) ≥ 4. It is found that 3 out of the 8 events yield tropospheric warming and stratospheric cooling. On the contrary, 4 out of the 8 events are tropospheric cooling and stratospheric warming. 1 out of the 8 events shows no obvious change. Results show that strong volcanic eruptions could trigger pressure waves which propagate upward eventually reach the ionosphere fluctuating on the electron density within it. The HHT (Hilbert-Huang Transform) is applied to compute spectra of perturbations in the vertical profile of the ionospheric electron density and find the wavelength being around 150km. Base on the speed-wavelength relationship, the period of the perturbations are 4 minutes.

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Thordarson, Thorvaldur. « Volatile release and atmospheric effects of basaltic fissure eruptions ». Thesis, 1995. http://hdl.handle.net/10125/9865.

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Carlsen, Hanne Krage. « Health effects of air pollution in Iceland : respiratory health in volcanic environments ». Doctoral thesis, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-89153.

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Air pollution has adverse effects on human health. The respiratory system is the most exposed and short-term changes in air pollution levels have been associated with worsening of asthma symptoms and increased rates of heart attacks and stroke. Air pollution in cities due to traffic is the major concern, as many people are exposed. However, natural sources of air pollution such as natural dust storms and ash from volcanic eruptions can also compromise human health. Exposure to volcanic eruptions and other natural hazards can also threaten mental health. Air pollution has not been extensively studied in Iceland, in spite of the presence of several natural pollution sources and a sizeable car fleet in the capital area. The aim of this thesis was to determine if there was a measurable effect on health which could be attributed to air pollution in Iceland. This aim was pursued along two paths; time series studies using register data aimed to determine the short-term association between daily variation in air pollution and on one hand daily dispensing of anti-asthma medication or the daily number of emergency room visits and emergency admissions for cardiopulmonary causes and stroke. The other method was to investigate if exposure to the Eyjafjallajökull volcanic eruption was associated with adverse health outcomes, either at the end of the eruption, or 6 months later. In paper I time series regression was used to investigate the association between the daily number of individuals who were dispensed anti-asthma medication and levels of the air pollutants particle matter with an aerodynamic diameter less than 10 μm (PM10), nitrogen dioxide (NO2), ozone (O3), and hydrogen sulfide (H2S) during the preceding days. For the study period 2006-9, there were significant associations between the daily mean of PM10 and H2S and the sales of anti-asthma medication 3 to 5 days later. Giving the exposure as the highest daily one-hour mean gave more significant results. Air pollution negatively affected the respiratory health of asthma medication users, prompting them to refill their prescriptions before they had originally intended to. In paper II the main outcome was the number of individuals seeking help at Landspitali University Hospital emergency room for cardiopulmonary disease or stroke. Time series regression was used to identify the lag that gave the best predictive power, and models were run for data for 2003-9 pollutants PM10, NO2, and O3. O3 was significantly associated with the number of emergency hospital visits the same day and two days later in all models, and both for men, women and the elderly. Only emergency hospital visits of the elderly were associated with NO2, and there were no associations with PM10. In paper III the aim was to investigate if the health effects of PM10 were affected by the addition of volcanic ash from the 2010 eruption of Eyjafjallajökull and 2011 eruption of Grímsvötn to PM10 in the capital area. Time series regression of emergency hospital visits and PM10 before and after the Eyjafjallajökull eruption showed that the effect tended to be higher after the eruption, but the results were not significant. Analysis with a binary indicator for high levels of PM10 from volcanic ash and other sources showed that volcanic ash was associated with increased emergency hospital visits. There were no associations with high levels of PM10 from other sources. In paper IV, the health of the population exposed to the ongoing eruption of Eyjafjallajökull in 2010 was investigated thoroughly. Lung function in adults was better than in a reference group from the capital area, though many reported sensory organ irritation symptoms and symptoms of stress and mental unhealth, especially those with underlying diseases. Paper V report the results from a questionnaire study which was carried out six months after the Eyjafjallajökull eruption. The study population comprised a cohort of south Icelanders exposed to the eruption to varying degrees and a reference group from north Iceland. Respiratory and eye symptoms were much more common in south Icelanders than in the reference group, after adjusting for demographic characteristics. Mental unhealth rates had declined considerably. In the studies, we found that urban air pollution and natural particles have short-term effects on anti-asthma medication dispensing and emergency room visits and hospital admissions. Exposure to natural particles in the form of volcanic dust was associated with increased respiratory symptoms in a very exposed population. There were indications that volcanic ash particles were associated with increased emergency hospital visits in the following days.

Statement of collaboration

This thesis and the work in it have been produced in collaboration between University of Iceland and Umeå University. The thesis was issued and defended at both institutions. Responsible

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Chen, Yu-Shu, et 陳玉樹. « Effects of salt and drought stress on plant distribution in Wushanting Mud Volcanic areas ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/07182822463226666572.

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碩士
國立高雄師範大學
生物科學研究所
90
Abstract This research is based on two different plants were sampling from the peak of Wushanting Mud Volcanic areas. The plants mentioned in this abstract consist of Bidens pilosa, a widely sprawling plant in the area, and Pluchea indica, a regional dominant plant found in this mountain. Aside from taking the samples from Wushanting, different ratios of mud were added into the planting, and the situation of drought was simulated a month later, so as to analyze the impact of salt and drought on the distribution of these plants. The result shows that the protein in Bidens pilosa sampled from the wild decreases slightly with the impact of drought, whereas Pluchea indica does not have this phenomenon. The amount of proline in Bidens pilosa alters with place and time, whereas the amount in Pluchea indica varies only with place. The total protein electrophoresis analysis for Bidens pilosa shows that a protein belt appears in places number 4 and 8 at 77KD, 55KD, 40KD, and 26KD. The analysis for Pluchea indica calls for a protein belt in 50KD and 26KD. Both Bidens pilosa and Pluchea indica demonstrate an increase of peroxidase as drought arrives, with the situation more apparent in Bidens pilosa. The results in peroxidase electrophoresis analysis show that when these two plants are situated under saline and water crisis situations, acid peroxidase belts appear to intensify. Although the total amount of protein for different mud proportions of Bidens pilosa does not alter greatly before the dehydration, the amount of proline in high proportions of mud (above 50%) will augment to over 4000ug/g, then show signs of death. The protein in low mud groups (below 33.3%) increases greatly after dehydration, but the amount of proline decreases, instead of increasing as expected. From total protein electrophoresis, we can discover that the total protein electrophoresis belt in the first 4 sample collection periods, particularly apparent near 55KD, 40KD and 26KD. Pluchea indica 100% and 75% mud groups demonstrated an obvious belt during the second sample collection at 26KD, and another during the fifth sample collection at 30KD. The peroxidase activity in high mud groups (over 50%) of Bidens pilosa is evidently more prominent than in low mud groups (below 33.3%), and it could reach up to 7 times the difference within groups. The peroxidase activity changes within Pluchea indica showed little difference before and after dehydration. After dehydration, the peroxidase of 100% and 75% lava groups increased 40 times the original amount, and the peroxidase activity of 50% and 25% lava groups increased 8 times. As for the 0% group, the increase of only 2 times was found. From the peroxidase IEF electrophoresis, we have discovered that the acid peroxidase belt intensifies with the increase of salt and dehydration. Peroxidase activity and proline affect the plants’ growth and their ability to resist tough environments, which in turn influences their adaptability of different surroundings. This research illustrates that Bidens pilosa and Pluchea indica show different reactions to difficult environments, particularly in the aspects of peroxidase activity and proline. Pluchea indica survives in highly saline areas (around the mud volcano) whereas Bidens pilosa distributes in non-saline environments.

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Cunha, Luis Filipe das Neves. « Effects of the extreme environment of volcanic origin in organisms : using earthworms as biological models ». Doctoral thesis, 2012. http://hdl.handle.net/10400.3/3968.

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Tese de Doutoramento, Biologia (Biologia Celular e Molecular), 18 de Maio de 2012, Universidade dos Açores.
Understanding how living processes persist under the challenges of intense physical or chemical stress emanating from diverse geogenic sources, such as those originated by volcanic activity have increasingly gained importance mainly compelled by biotechnology imperatives. Volcanically active regions, such as Furnas, a geothermal field located in São Miguel Island (Azores), often have a high-density of human inhabitants due to the elevated natural fertility of its soils, despite of creating significant risk scenarios of exposure to a wide range of chemical substances. The volcanic gases at the Furnas caldera create a hypoxic and hypercapnia environment combined with 10˚ C elevated soil temperatures and acidic conditions promoting bioavailability of heavy metals. These tripartite stress factors combine to create an in-hospitable challenge to the resident biota; therefore, it is surprising that this extreme soil environment supports a viable earthworm population. In fact, the epidermis of Amynthas gracilis resident on Furnas soil is ~50% thinner than the respiratory exchange surface in conspecifics resident on inactive volcanic soils. This was also found in resident Pontoscolex icorethrurus. This leads to the plausible conclusion that the earthworm’s responses to the multi-stressor challenges in active volcanic soils are, like the adaptations of arthropods and vertebrates to hypoxic conditions, multifactorial and involve integrated modifications ranging from genetic and biochemical, to cellular and physiological levels of organization. Analyses of mitochondrial data using different approaches corroborate the existence of two different genetic lineages living in São Miguel Island. Furnas population showed lower genetic diversity when compared to the populations living within pineapple plantations. Molecular markers included the mitochondrial regions of the cytochrome c oxidase subunit I gene (COI), small ribosomal unit (s- rRNA), the NADH desidrogenase subunit 2 and 3. The importance of genetic reduction in the population genetic structure of earthworms living under the stress of the volcanic environment is further discussed. Analysis using AFLP markers showed Pontoscolex corethrurus to be a genetically heterogeneous complex with direct association with the previous results of mitochondrial divergence. The complete congruence between molecular markers suggests that cryptic speciation is a plausible explanation for the deep mitochondrial divergence in P. corethrurus in São Miguel Island. Four pairs of primers generated 425 loci. The average ratio of polymorphic loci among the studied populations was of 84%. Shannon information index was 0.28 with a higher value of 0.3 in Furnas. These results show that the genetic diversity detected with AMOVA was mainly caused by individual differences within a population. In fact, three different ancestral clusters were identified among populations. One cluster showed to be almost exclusive to Furnas individuals showing and confirming the genetic differentiation of this apparently isolated geographic group. On the one hand it is plausible to consider that the homogenizing effect of selection on genomic diversity would intensify in populations successfully inhabiting intensely stressful environmental conditions, such as actively volcanic soils. In contrast, an intriguing alternative scenario may pertain where chemical contaminants increase genetic diversity by causing genomic mutation which could explain why Furnas population showed the highest number of private bands. Microbial populations associated with the earthworms revealed some conspicuous results. Some bacteria were found in both earthworm populations as resident microbial flora (e.g. Nitrobacter, Serratia, Bradyrhizobium, and Methylobacterium) while others seem to be restrict to one of the studied populations. The Azorean P. corethrurus has some conspicuous genera such Anaeromyxobacter and Desulfovibrio that may result of adaptations to the environment in which the host lives. This is also the first report of Verminephrobacter phylotypes within the Pontoscolex genus. With this project was possible to elucidate some of functional mechanisms employed by annelids that allow it to maintain viable populations in soil exhibiting elevated heavy metal availability, low oxygen/high CO2 content and a high ambient temperature (~37˚C) as well the consequences of living under such environment revealed at genetics level from the individual to the population.
This study was financially supported by CIRN (University of the Azores), DRCT (Government of the Azores) and by the research grant PTDC/AAC-AMB/115713/2009 from Fundação para a Ciência e Tecnologia (FCT). Luis Cunha was supported by a Doctoral grant from DRCT (M312/F/029/2007).

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Marske, Katharine Ann. « Effects of volcanic ash on the insect food of the Montserrat Oriole Icterus oberi Lawrence 1880 ». 2005. http://etd.lib.montana.edu/etd/2004/marske/MarskeK0804.pdf.

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Morrow, James W. « A longitudinal study to characterize Hawaiʻi's volcanic aerosol and investigate its potential acute effects on asthmatic children ». 2000. http://wwwlib.umi.com/dissertations/fullcit/9968046.

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Matz, Stephan E. « The effects of the Mazama tephra-falls : a geoarchaeological approach ». Thesis, 1987. http://hdl.handle.net/1957/33997.

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About 7,000 years ago two major tephra-falls blanketed the Pacific Northwest in volcanic ash. These two tephra-falls, identified as the Llao and climatic tephra-falls, were a part of the eruptive events that led up to the collapse of Mount Mazama to form Crater Lake in the southern Oregon Cascades. The tephra-falls occurred about 200 years apart at around 7,000 years B.P. and 6,800 years B.P. for the Llao and climatic eruptions respectively. The effects of the tephra-falls on the flora, fauna, and people of the period have been characterized by different researchers as ranging from minimal to catastrophic. In an attempt to better understand the affects of these two events on the flora, fauna, and people, a model is presented to help organize the various lines of research into a coherent whole and to suggest profitable areas of research which have not yet been completed. The model is based on ecological and anthropological theory with a strong reliance on analogy with modern ecosystems and volcanic hazards research. The model makes use of the ecosystem concept as the framework for the interaction of the abiotic, or nonliving habitat, with the biotic, or living system. The biotic organisms are adapted to the characteristics of the abiotic habitat and in many respects the composition, frequencies, and distributions of biotic organisms are determined by their tolorance levels to these characteristics. Tephra-falls act as environmental disturbances which change the abiotic habitat of the ecosystem. Therefore, any changes caused by such a disturbance in the abiotic characteristics that are not optimal or are outside of the tolorance limits of the biotic (flora and fauna) components should cause changes in the composition, distribution, and frequency of organisms within the ecosystem. The changes brought about by the tephra-falls may be described by successional and evolutionary processes through analysis of pollen and faunal remains, population demography as described by mortality profiles, and research into the reaction of specific flora and fauna within adaptational types to the properties of tephra-falls and the tephra as a soil body. The state factors used to describe the abiotic component of the ecosystem are: time, distribution, material properties, climate, and geomorphology. The state factor of time involves the determination of the occurrence in time of the event(s), the duration of the event(s), the season of occurrence of the event(s), and the residence time of tephra in the ecosystem. This state factor is used to define the specific point in time and duration of the effects of the tephra-fall(s) for individual ecosystems. The state factor of distribution describes the aerial extent and thickness of the air-fall deposits. This state factor determines the extent of the initial disturbance. The state factor of climate describes the specific components of rainfall, wind, and temperature which control ecosystem composition and development, and the changes to the climate which may have occurred due to volcanic aerosols associated with the eruption. The state factor of geomorphology describes the location of tephra and nontephra bodies across the landscape and through time as the tephra is reworked by wind, water, and gravity from the initial air-fall positions. The determination of the long term distribution of the tephra is important in determining post-event influences on ecosystems as described by the material properties of the tephra. It is argued that most people were not greatly harmed by the Mazama tephra-fall events themselves, but instead may have been greatly affected by a loss of food resources during and after the events. Changes in food resource availability and exploitation locations due to the tephra-falls may have resulted in changes in both settlement and subsistence activities. Changes in settlement and subsistence activities may be seen in a corresponding change in differential frequencies of functional tool types across space and time. The kind and amount of expected changes in settlement and subsistence systems are linked to distance from the source of the tephra, the stability and compostion of pre-disturbance ecosystems, the types and intensity of resource exploitation, and the amount of variability in subsistence and settlement traits which were available to the sociocultural system.
Graduation date: 1988

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Krupitsky, Dmitry. « Effects of volcanic gas (vog) on the lung function and self-reported symptoms of Hawai'i Volcanoes National Park workers ». Thesis, 2008. http://hdl.handle.net/10125/20437.

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Thesis (Ph.D.)--University of Hawaii at Manoa, 2008.
Conclusion. Visual vog observers can provide reliable data which are correlated with data from SO2 and PM1.0 monitors. Visually observed vog is as useful tool of predicting self-reported symptoms as SO2 and PM1.0 monitors. Network of visual observes can provide useful assessment of the park.
Introduction. Kilauea, the largest stationary source of sulfur dioxide (SO2) in the nation, has been erupting continuously since 1986. The visible cloud (vog) formed by emitted gases in combination with moisture and sunlight may be directed by the wind and can be visible throughout the Hawaii Islands. Kilauea is located in the Hawaii Volcanoes National Park (HVNP) which has 5,000 visitors daily and is the workplace of 750 employees who have the highest exposure to vog.
Methods. This cohort study was designed to examine the association between volcanic emissions (vog) as indicated by the degree of particulate matter (PM1.0), sulfur dioxide SO2, and visual assessment (VVI) and its impact on self-reported symptoms and lung function measurements in HVNP workers. Self-reported symptoms and PEF and FEV1 measurements were recorded daily by park workers and volunteers.
Results. Visually observed vog, PM1.0 and SO2 were statistically significantly associated with self-reported symptoms: cough, wheeze, headache, shortness of breath, sore, itchy, watery eyes, and irritation of nose/sinus/throat but not with PEF and FEV1. Increases in SO2 seemed to have an immediate (0 days lag) effect on symptoms; during maximum SO2 days of the period of study (SO2 max = 173 ppb) the odds of having symptoms increased by two fold for the same day compared to days with the lowest SO2 measurement (SO2 min = 0 ppb). The greatest relationship between PM1.0 and symptoms is delayed by one day; one day after the maximum PM1.0 (PM1.0 max = 7.85 um/m3), the odds of having symptoms increase by 1.5 times compared to days with the lowest PM1.0 measurement (PM1.0 min = 0 ppb). In contrast, the relationship between visual vog index (VVI) and symptoms seem to be greatest two days after exposure; two days after "heavy haze" (VVI = 3) the odds of having symptoms increase by 1.53 compared to "clear" days (VVI = 0).
Includes bibliographical references (leaves xxx-xxx).
Also available by subscription via World Wide Web
181 leaves, bound 29 cm

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Wu, De-Lun, et 吳德倫. « The effect of exotic species habitat expansion on arthropod disease vectors in a volcanic island ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/rg778g.

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碩士
國立臺灣師範大學
生命科學系
107
Lack of predators and competitors in small and hard-to-reach volcanic oceanic islands can facilitate ecological release of introduced species, including rodents that serve as hosts or reservoirs of a variety of zoonotic diseases. The volcanic Lanyu Island has a high prevalence of scrub typhus, which is transmitted by chigger mites; in addition, spotted fever group rickettsiae have been detected in hard ticks. Rodents are the primary hosts of chiggers and hard ticks. The rodent community in Lanyu is dominated by the exotic Asian house rat (Rattus tanezumi), which can be observed in different types of habitats, including grasslands and natural forests. This is in contrast to Taiwan main island where this species is limited to human residence areas. This study investigated the role of the Asian house rat in hosting chiggers and ticks and whether the grasslands and natural forests in Lanyu also shelter chiggers and ticks. From September 2017 to June 2018, we set up rodent traps and collected ectoparasites from captured rodents in each of the three human residence sites, three grassland sites, and four natural forest sites. Results showed that the Asian house rat was the only rodent trapped across all three habitat types. Abundance of R. tanezumi was significantly lower in human residence sites (2.9±0.8 individuals; mean±SE) than in grasslands (5.9±1.2; p < 0.05) and in forests (9.3±1.3; p < 0.001); their abundance in grasslands also lower than in forest (p < 0.05). Meanwhile, rat abundance was significantly higher in December (10.3±1.9) than the other month (all p < 0.05). All rats were infested with chiggers, which includes three species, although the chigger fauna is dominated (>95%) by Leptotrombidium deliense. There was a significant interactive effect of habitat and season on mean chigger load (total number of chiggers/number of rats; p < 0.001); seasonal change in mean chigger load varied among human residence (285.8±84.9), grasslands (545.5±100.9) and forests (450.7±77.1). The grasslands had the highest total number of chiggers in September(5579.3±1519.1), while total number in forests peaked in June(4958.0±1357.4). Prevalence of tick infestation was 64.6%. Three tick genus were identified, with Ixodes granulatus being the most commonly observed (>70%). Mean ticks load (total number of ticks/number of rats) was significantly lower in human residence (0.9±0.4) than in grasslands (14.8±8.1; p < 0.001); while forests (6.9±1.9) did no differ from the other two habitats (both p > 0.05), and December had a significantly lower tick load than the other months (p < 0.001). In September and December, the total number of ticks in grasslands and in forests were significantly higher than in human residence (p < 0.001), and increased significantly in March (all p < 0.05). This study found that the exotic Asian house rats, and the chiggers and ticks that they carry, are also observed in grasslands and forests of Lanyu, and usually attained higher abundance than in human residence sites. These results suggest that the introduction of exotic rodents to volcanic islands will not only have devastating effect on ecosystems but can also increase human exposure to rodent-borne diseases.

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Juhariah, Jujuk, et Jujuk Juhariah. « Effect of Merapi Volcano Eruption on Land Use Change and Agriculture ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/93582253369902347974.

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碩士
國立東華大學
自然資源與環境學系
104
ABSTRACT JUJUK JUHARIAH. The Effect of Merapi Volcano Eruption on Land Use Change and Agriculture. Adviser: Prof. Zue-Er Chen There are four purposes of this research. To know the effect of Merapi Volcano eruption on land use change and agriculture. Identify the most suitable crops in for affected areas. To advise the Sleman government about more suitable land use, thus increasing the local potential. To help the farmers overcome negative effects of the eruption as soon as possible. This research conducted in Cangkringan District, Sleman Regency, Yogyakarta Province, Indonesia and only focused on three eruptions, 2001, 2006, and 2010. The methodologies to do this research are interview, questionnaire, observation, collect data from Sleman Regency Government, and study the satellite images from the United States Geological Survey. The researcher interviews seven government officers and uses 300 questionnaires to get the information from the farmers. The researcher observes the study site and distributes the questionnaire at the same time. Data from Sleman Regency government is about the farming product of Cangkringan and maps of Sleman Regency. This research use satellite images from Landsat 7 ETM+ starts from 2000-2011 in path 120 and row 65. The result shows that the eruption in 2001 and 2006 did not gives significant effect on land use change and agriculture in Cangkringan. The eruption in 2010 gives huge effect to the land use and agriculture in Cangkringan. Agriculture is the most suitable land use in Cangkringan. In addition, the suitable crops for the areas around Merapi Volcano are corn, peanut, spring onions, and onions that resistant to silica content in the fresh volcanic soil. To improve the local potential and improve the socio-economic level for people in Cangkringan, a combination of agriculture and tourism industry in Cangkringan can be use. Key words: Merapi Volcano, eruption, Cangkringan, agriculture, land use, socioeconomic

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Hill, Brittain E. « Petrogenesis of compositionally distinct silicic volcanoes in the Three Sisters region of the Oregon Cascade Range : the effects of crustal extension on the development of continental arc silicic magmatism / ». 1991. http://hdl.handle.net/1957/10395.

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Tsitas, Steven R. « I. The effect of volcanic aerosols on ultraviolet radiation in Antarctica. II. A novel method for enhancing subsurface radar imaging using radar interferometry ». Thesis, 1998. https://thesis.library.caltech.edu/7456/1/Tsitas%201998.pdf.

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The theory of radiative transfer is used to explain how a stratospheric aerosol layer may, for large solar zenith angles, increase the flux of UV-B light at the ground. As previous explanations are heuristic and incomplete, I first provide a rigorous and complete explanation of how this occurs. I show that an aerosol layer lying above Antarctica during spring will decrease the integrated daily dose of biologically weighted irradiance, weighted by the erythema action spectrum, by only up to 5%. Thus after a volcanic eruption, life in Antarctica during spring will suffer the combined effects of the spring ozone hole and ozone destruction induced by volcanic aerosols, with the latter effect only slightly offset by aerosol scattering.

I extend subsurface radar imaging by considering the additional information that may be derived from radar interferometry. I show that, under the conditions that temporal and spatial decorrelation between observations is small so that the effects of these decorrelations do not swamp the signature expected from a subsurface layer, the depth of burial of the lower surface may be derived. Also, the echoes from the lower and upper surfaces may be separated. The method is tested with images acquired by SIR-C of the area on the Egypt/Sudan border where buried river channels were first observed by SIR-A. Temporal decorrelation between the images, due to some combination of physical changes in the scene, changes in the spacecraft attitude and errors in the processing by NASA of the raw radar echoes into the synthetic aperture radar images, swamps the expected signature for a layer up to 40 meters thick. I propose a test to determine whether or not simultaneous observations are required, and then detail the radar system requirements for successful application of the method for both possible outcomes of the test. I also describe in detail the possible applications of the method. These include measuring the depth of burial of ice in the polar regions of Mars, enhancing the visibility of buried features and, most importantly, the ability to map soil moisture in arid regions of the earth at high spatial resolution.

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Mora, Fernandez Mauricio. « Etude de la structure superficielle et de l'activité sismique du volcan Arenal, Costa Rica ». Phd thesis, 2003. http://tel.archives-ouvertes.fr/tel-00766832.

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Le volcan Arenal présente une activité explosive continue de type strombolien caractérisée par l'effusion permanente de coulées de lave, la formation d'écoulements pyroclastiques et une sismicité intense. Cette activité est suivie depuis 1974 par l'Observatorio Sismologico y Vulcanologico de Arenal y Miravalles (OSIVAM) rattaché à l'Institut Costarisien d'Electricité (ICE). Dans la première partie de ce travail, nous avons étudié l'activité volcanique de l'Arenal entre 1986 et 2000 à partir des données obtenues par l'OSIVAM que nous avons regroupées en une base de données unique. Nous avons analysé ces informations en nous focalisant sur le comportement du volcan à l'échelle de plusieurs années. Il est actuellement difficile d'établir si les évolutions des paramètres observés reflètent de réelles modifications de l'activité éruptive de l'Arenal. Nous avons mis en évidence les limites du système de surveillance et nous proposons des améliorations.La suite de ce mémoire est une étude de la structure de l'activité sismique réalisée à l'aide de plusieurs réseaux denses de capteurs (triangles, demi-cercles, profils, réseaux en L). A partir des données de deux profils sismiques déployés à l'Est et l'Ouest du volcan, nous avons analysé les effets de la structure sur les signaux sismo-volcaniques. De fortes variations de l'amplitude des pics spectraux sont observées localement le long des profils. Nous avons étudié ces anomalies en utilisant la méthode des rapports spectraux U/V et avons montré que la forme de ces rapports est indépendante du type de signal utilisé. Les résultats mettent en évidence dans certains sites des effets de résonance à des fréquences qui correspondent à celles des amplifications observées. Des fonctions de transfert théoriques des ondes S ont été calculées en chaque site en utilisant des modèles de vitesse obtenus par sismique réfraction. Lorsqu'il existe un contraste d'impédance suffisant entre les couches peu consolidées et les couches plus profondes les rapports spectraux et les fonctions de transfert présentent des pics de même fréquence. Cela montre le lien entre les amplifications observées et la structure géologique. Nous avons également sondé la structure superficielle de l'Arenal en utilisant la méthode d'auto-corrélation spatiale basée sur le calcul de coefficient de corrélation entre station de réseaux semi-circulaires. Nous avons amélioré l'inversion de ces coefficients pour mieux estimer les vitesses de phase des ondes de surface. A l'ouest du volcan, les vitesses des ondes de Rayleigh varient de 765 m s-1 à 1 Hz à 300 m s-1 à 12 Hz et pour les ondes de Love entre 780 et 295 m-1 dans la même bande de fréquence. A l'est, les vitesses des ondes de Raleigh sont comprises entre 1386 et 300 m s-1 et celle de Love entre 1983 et 315 m s-1. Ces courbes de dispersion ont ensuite été inversées pour obtenir des modèles de structure, en tenant compte des connaissances géologiques disponibles. Les modèles de vitesse obtenus sont cohérents avec les résultats de sismique réfraction et les calculs de rapports spectraux. L 'analyse d'enregistrements continus large bande montre une grande variété de comportement du trémor et des explosions volcaniques. Les résultats révèlent notamment l'existence de deux processus de résonance non stationnaires pouvant se produire simultanément mais ayant des caractéristiques spectrales différentes. Cela suggère qu'à certains moments, deux sources de trémor peuvent être actives. Les méthodes auto-régressives utilisées fournissent des mesures robustes et de haute résolution fréquentielle et temporelle de la fréquence des pics spectraux. Elles montrent également que les fréquences et les facteurs de qualité de ces pics varient rapidement au cours du temps, reflétant des évolutions des propriétés physiques des sources sismo-volcaniques..

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LIAN, CHEN YU, et 陳玉蓮. « Effect of Temperature, Photosynthetic Photon Flux, and Simulated Dark Transport on Growth andFlowering of Oncidium Puli Grifith, Gower Ramsey ‘Volcano Queen’ and Colmanaras Wildcat ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/56519422212211119512.

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碩士
國立臺灣大學
園藝學研究所
90
The effect of day/night temperature and photosynthetic photo flux ( PPF ) on growth cycle, flowering quality and photosynthesis of Onc. Puli Grifith, Gower Ramsey ‘Volcan Queen’ and Colm. Wildcat. Plants Onc. Puli Grifith with 2 back shoots (after deflask for 11months ) were grown in Puli and plants Colm. Wildcat with 2 back shoots ( after deflask for 18months ) were grown at phytotron 20℃ day/15℃night, accumulated hightest carbohydrate and hightest flower stalk emergence rate 70% and 92%, respectively among the treatments (Taipei, 30/25℃ and 25/20℃ ). However, low temperature ( 20/15℃) delay pseudobulb maturation and new shoot sporuting of plant. The flowering quality in 4th generation was better than 3rd generation among all treatments. The 3rd and 4th generations of Colm. Wildcat grown in lowland of Taipei under Venlo glasshouse with fan-and-pad cooling system emerged double flower stalk and produced excellent inflorescence quality. So, we subjected the young plant grown in 20 — 30℃ temperature range, subsequent flowering plant should be grown in lower temperature about 15 — 25℃. The net photosynthetic rate of Colm. Wildcat was 4 — 5 CO2μmol•m-2•s-1 at range of 16 — 23℃ was hightest than Onc. Puli Grifith and Gower Ramsey ‘Volcan Queen’, respectively. When temperature reached 34℃, the photosynthetic rate of Colm. Wildcat still maintained about 3 CO2μmol•m-2•s-1, but Onc. Puli Grifith and Gower Ramsey ‘Volcan Queen’ decresed to 1.5 CO2μmol•m-2•s-1. It was showed Wildcat had higher net photosynthetic rate than Onc. Puli Grifith and Gower Ramsey ‘Volcan Queen’. During the late of spring in Taipei, the PPF reach to 600μmol•m-2•s-1 and temperature reach to 40℃ at noon, the net photosynthetic rate decreased nearly to 0 CO2μmol•m-2•s-1 in polycarbonate roof greenhouse with natural ventilation. In the afternoon under high temperature ( 33℃) and low light ( below 200μmol•m-2•s-1 ), the photosynthetic rate still maintained in 1 CO2μmol•m-2•s-1. The data showed high temperature deceresed net photosynthetic ratewhich caused low carbohydrate content in pseudobulb, then failure to emerge flower stalk in Colm. Wildcat. Mature plants of Onc. Puli Grifith and Gower Ramsey ‘Volcan Queen’ with flower stalk 3 — 5cm in length, forced in 23/18℃, the floret number increased significantly various irradance from 5 to 200μmol•m-2•s-1. Plants with flower stalk 3 — 5cm in length simulated dark transport at 18±1℃ for 4, 7days, Then forced in 25/20℃, 20/15℃or 180μmol•m-2•s-1 reduced floret number and longevity but still have acceptable quality for sale. Plants with 2 back shoots which accumulated less carbohydrate and compared with 3 back shoot were more susceptable to dark stress.

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Mazzini, Virginia. « Specific ion effects in non-aqueous solutions ». Phd thesis, 2017. http://hdl.handle.net/1885/144595.

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Electrolyte solutions play a central role in life and technological processes because of their complexity. This complexity is yet to be described by a predictive theory of the specific effects that different ions induce in solution. The vast majority of investigations of specific-ion effects have been conducted in aqueous solutions. These studies have revealed that amongst the complexity, the effectiveness of the ions often follow trends that are apparent across a number of very different experiments, revealing an underlying order (e.g. the Hofmeister series). It is often assumed that water itself is intricately involved in these trends. Here I investigate specific-ion effects in non-aqueous solvents rather than water. By extending the investigation to a number of non-aqueous solvents, the role of the solvent in specific-ion effect trends can be elucidated and a better understanding of the general phenomenon gained. Firstly, a more definite terminology is developed for describing the specific-ion effects trends in order to address the current confusion in the literature and provide a basis for the following investigations. An extensive investigation of the scarce literature demonstrates that water is by no means a special solvent with regards to ion-specificity, and that within the complexity there is universality. An investigation of electrostriction under the conditions of infinite dilution shows that the same fundamental specific ion trends are observed across all solvents, demonstrating that ion-specificity arises from the ions themselves. In this regard the influence of solvents, surfaces and real concentrations of electrolytes can be seen as perturbations to this fundamental series. Further work shows that for systems that are perturbed, the trends in non-aqueous protic solvents can be expected to follow the same trend in water; and in aprotic solvents the cations are more likely to adhere to the trend in water than the anions. My experimental work focuses on specific-anion effects of seven Hofmeister sodium salts in the solvents: water, methanol, formamide, dimethyl sulfoxide and propylene carbonate. Two very different experiments were performed; the elution of electrolytes from a size-exclusion chromatography column and an investigation of the electrolyte moderated swelling of a cationic brush (PMETAC) using a Quartz Crystal Microbalance (QCM). The trends observed are consistent across these experiments. A forward or reverse Hofmeister series is observed in practically all salt-solvent combinations, and the reversal is attributed to the polarisability of the solvent. Finally, a qualitative model of ion specific trends is formulated, where the specific-ion effects are fundamentally a property of the ion, and the associated trends correspond to the Hofmeister series for anions and the lyotropic series for cations. When the concentration is increased, or surfaces introduced, the effects of ion-ion interactions and ion-surface interactions can perturb the fundamental series. The perturbation of the series is related to the proticity of the solvent for ion-ion interactions, whereas the polarisability of the solvent and ion are important when a surface is present. This work for the first time individuates the principal properties of the solvent that affect their ordering: proticity and polarisability.

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