Dissertations / Theses: 'Volcanic impacts'

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Witham, Claire Suzanne. "Volcanic plumes : impacts, chemistry and dispersion." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615011.

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Peters, Michael Steven. "Temporal impacts of volcanic ash in freshwater systems." Thesis, University of Canterbury. Geological Sciences, 2012. http://hdl.handle.net/10092/7639.

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Volcanic ash can cause acidification and metal contamination of freshwater systems. Shmt-te1m chemical and pH fluxes in water have been attributed to dissolution of the ash surface film while dissolution of the glassy matrix has been linked to metal input over longer time periods. The rate at which ash surface film and glassy matrix dissolution occurs and the associated impact of ash to freshwater pH and chemistry over time has not previously been established. The influence of volcanic ash BET surface area on initial pH fluxes and metal dissolution rates in freshwater systems was investigated using pristine basaltic-andesite volcanic ashes from Mt. Ruapehu (New Zealand), Mt. Sakurajima (Japan) and Soufriere Hills (Montserrat). The aim of this study was to investigate the bi-temporal hazard of volcanic ash in freshwater systems including freshwater drinking-water supplies. All ashes provided an immediate pH decrease to water that was directly related to sulphur concentrations released from ash surface film (p < 0.02). The maximum pH decrease was observed after 2.5 minutes. The rate of change was independent of ash surface area due to the high solubility of the surface film. Initial pH decreases for all ashes were transient with the degree of acidification lessening following surface film removal via water rinse(s) and time in solution. The rapid rate of dissolution means in 'real-world' settings the surface film will be removed within the upper layer of a water body and will only provide a shmt-te1m source of acidification and chemical contamination. Release rates for (Al, Mn and As) from the glassy matrix of ashes over longer-time periods (0-1 00 hours) were dependent on BET surface area and ash to water ratios for each ash. The influence of differing physical and chemical characteristics between the three ashes, however, prevented surface area being used as a proxy for all dissolution rates. The metal release rates were used to calculate the time needed for the drinking water quality guidelines to be exceeded under three different ashfall scenarios. Using the derived metal release rates for the Mt Ruapehu Ash, Al was the element most likely to exceed the drinking water standards. This exceedance can be attributed to the relatively fast release rate (Al 10.4 flg h -I m-2 ) and high concentration within the ash (14% by weight). An ashfall of 1 Omm would result in exceedances of the drinking water standards for AI in the Waitakere and Hays Creek Reservoirs (Auckland city water supply) after ~8 hours.

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Giles, Teresa Mary. "Volcanic emissions and distal palaeoenvironmental impacts in New Zealand." Thesis, University of Plymouth, 1999. http://hdl.handle.net/10026.1/2176.

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This thesis is a palaeoenviromnental investigation into possible non-climatic effects on the environment from volcanic ash fall and toxic emissions outside the blast zone of a volcanic eruption. These effects are determined from palynological and geochemical changes following tephra fall at a range of sites across the North Island of New Zealand which were located at increasing distances from the main volcanic source, the Taupo Volcanic Zone. These sites collectively covered a wide variety of habitats existing under different climatic regimes. The first site is a peat bog at a warm temperate, comparatively unstable coastal location, Matakana Island. The peat profile extends to 1000 yrs BP and contains the Kaharoa Tephra layer, erupted around the time of early human settlement in New Zealand. The second study site is Kaipo peat bog which, in contrast to Matakana Island, is an upland sub-alpine site existing under a harsher climatic regime with cool temperatures, strong winds and heavy rainfall. The Kaipo record covers the Holocene period up to recent times. Lake Rotoroa is the third site which is located inland, sheltered within the Waikato valley, an area of rich fertile soils and mild temperate climate. The Lake Rotoroa record extends to approximately 15,000 yrs BP including the end of the last glacial period and the Holocene. The final site investigated, Kohuora bog, is situated in an extinct late Quaternary volcanic crater within Auckland urban area, a region of warm temperate climate. This record extends from the last glacial period to the present. Fine resolution sampling methods were employed above tephra layers preserved at each of these sites to examine the immediate short-term palaeoenvironmental impacts from volcanic tephra deposition. The methods used included pollen analysis, and the relatively new technique of Energy Dispersive X-ray Micro Analysis (EDMA) which investigated changes in sediment geochemistry to provide further information on local environmental change following tephra impact. The use of pollen analysis together with EDMA proved beneficial in assessing overall short term environmental impacts from tephra fell. Results revealed that thicker tephra layers did not always cause extensive environmental damage, as impacts seen above the 0.5 cm thick Egmont 15 Tephra at Lake Rotoroa were among the most significant recorded at this site. Instead, the contributing factors of prevailing climate and local site factors (e.g. drainage, soils, vegetation cover and shelter) at the time of an eruption, together with local forest diversity and species sensitivity to tephra deposition, proved more important in determining the degree of tephra impact. Taxa found to be particularly sensitive to tephra deposition included Halocarpus, with inconsistent impacts from tephra fell on Dacrydium and Metrosideros. Duration of tephra impacts varied between sites, but broad estimates from the results showed the time taken for recovery of forest vegetation following an eruption was >100 years, with environmental stability returning after a minimum period of 50 years. The results from Matakana Island revealed that any possible tephra impacts from deposition of the Kaharoa Tephra were obscured owing to large-scale deforestation following Polynesian settlement on the island around the time of the Kaharoa eruption. This study indicates the importance of investigating distal volcanic impacts prior to human settlement to eliminate ambiguity in interpretation of palaeoenvironmental data.

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Driscoll, Simon. "Climate impacts of stratospheric particle injection." Thesis, University of Oxford, 2014. https://ora.ox.ac.uk/objects/uuid:5460c624-75d0-448e-b9a0-c1bc70cc9ad0.

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Geoengineering has attracted large attention over recent years as to being a possible way to ameliorate some of the effects of climate change. One of the proposals, involving injecting sulphate aerosols into the stratosphere in order to cool Earth's temperature back to pre-industrial levels, has been assessed as one of the leading geoengineering proposals. Despite this, large uncertainties remain in both the physical and social sciences. Small scale trials of sulphate aerosol injection are not seen as ways to provide large amounts of useful data to inform on the climate response to stratospheric sulphate aerosol loading (whilst also facing many social and ethical barriers). Large scale trials involving injecting amounts of aerosol more comparable to what would be required to cool the Earth's temperature back to pre-industrial levels are viewed as too risky. Assessments of the climate effects of sulphate aerosol geoengineering by the scientific community therefore have largely relied on climate modelling studies. The thesis begins by reviewing sulphate aerosol geoengineering and the modelling that have been conducted to date. In light of the need to verify modelling results with observations the thesis seeks to understand the effects of nature's analogue to sulphate aerosol geoengineering: large volcanic eruptions. When a volcano erupts it can inject large amounts of SO2 gas into the stratosphere, which then undergo conversion to form sulphate aerosol, cooling the Earth in a way analogous to sulphate aerosol engineering. The ability of the climate models submitted to the Coupled Model Intercomparison Project 5 (CMIP5) database is assessed, with a particular focus on dynamical changes in the Northern Hemisphere winter period. These models fail to capture the observed NH dynamical response following eruptions, which is of concern for the accuracy of geoengineering modelling studies that assess the atmospheric response to sulphate aerosol geoengineering. Simulations of volcanic eruptions are then performed with high-top and low-top configurations of the HadGEM2-CC climate model. The high-top version of HadGEM2-CC, with enhanced vertical resolution and model height, gives a markedly improved and statistically significant post-volcanic winter dynamical simulation to its low-top counterpart. The post-winter dynamical simulation in the high-top model agrees with the observed response following volcanic eruptions. Accordingly, mechanisms involved in the dynamical changes are analysed and it is concluded that the HadGEM2-CC high-top model would give more confident simulations of sulphate aerosol geoengineering over its low-top counterpart. Given the identification of a more suitable model for geoengineering simulations following extensive investigation, the final chapter analyses simulations of the HadGEM2-CC high-top model for asymmetries between the climate response to an immediate onset of geoengineering and a rapid cessation of geoengineering - known as a 'termination' of geoengineering. The project is summarised and discussed, and future work is proposed, involving a large host of projects.

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Jones, Anthony Crawford. "Investigating the climatic impacts of stratospheric aerosol injection." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/27786.

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In this thesis, we assess various climatic impacts of stratospheric aerosol injection (SAI), a geoengineering proposal that aims to cool Earth by enhancing the sunlight-reflecting aerosol layer in the lower stratosphere. To this end, we employ simpleradiative transfer models, a detailed radiative transfer code (SOCRATES), and two Hadley Centre general circulation models (HadGEM2-CCS and HadGEM2-ES). We find that the use of a light-absorbing aerosol (black carbon) for SAI would result in significant stratospheric warming and an unprecedented weakening of the hydrological cycle. Conversely, we find that SAI with sulphate or titania aerosol could counteract many of the extreme climate changes exhibited by a business-as-usual scenario (RCP8.5) by the end of this century. In a separate investigation, we show that volcanic aerosol dispersion following low-altitude volcanic eruptions can exhibit high sensitivity to the ambient weather state. Volcanic aerosol may get 'trapped' in a single hemisphere or transported to the opposite hemisphere depending simply on the meteorological conditions on the day of the eruption. In a final study, we investigate the impacts of SAI on North Atlantic tropical storm frequency. We find that SAI exclusively promoted in the southern hemisphere would increase North Atlantic storm frequency, and vice versa for northern hemisphere SAI. The results of this thesis should promote further research into SAI, which could conceivably be deployed to maintain global-mean temperature below the COP21 target of +1.5 K above pre-industrial levels, whilst society transitions onto a sustainable energy pathway. Conversely, the possibility of SAI being weaponised, for instance, to specifically increase North Atlantic tropical storm frequency, should motivate policymakers to implement effective regulation and governance to deter unilateral SAI deployments.

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Schmidt, Anja. "Modelling tropospheric volcanic aerosol : from aerosol microphysical processes to Earth system impacts." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540764.

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Scaini, Chiara. "Modeling strategies for volcanic ash dispersal and management of impacts on civil aviation." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/288372.

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During April-May 2010, the eruption of Eyjafjallajokull volcano in Iceland caused the larger breakdown of civil aviation after World War II. Although the eruption was weak in intensity, the dispersal of volcanic ash clouds over northern and central Europe resulted in more than 100.000 flights canceled and caused over USD 1.7 billion economical losses. This event and its unexpected effects raised many questions amongst the affected communities and stakeholders. How could volcanic eruptions cause severe disruptions at continental scales? Were these impacts totally unexpected? What could have been done to improve preparedness of aviation sector and reduce societal impacts of disruptions? The harmful effects of volcanic ash on aircraft's components have long been recognized, and volcanic ash dispersal patterns can be forecasted thanks to sophisticated numerical models. However, the procedures to be implemented in case of ash-contaminated airspace where applied only in few occasions, due to the relatively low frequency of explosive eruptions events. The 2010 Eyjafjallajokull crisis revealed a low preparedness of society to direct and indirect impacts of volcanic eruptions, and pointed out some flaws to be improved for mitigating impacts of explosive eruptions on aviation operations. The issues pointed out by the 2010 crisis are the starting point of this PhD research, which aims at offering new methods for improving aviation management during explosive volcanic eruptions. This manuscript describes the novel contributions developed during a 4-year period of research. The adoption of new techniques is proposed in order to improve current tephra dispersal modeling strategies and produce results focused on aviation needs. This research develops the first methodology to assess vulnerability of air traffic system and its elements to volcanic tephra dispersal. In addition, an impact assessment methodology has been designed to estimate expected impacts of explosive volcanic eruptions on the air traffic network and its elements. The impact assessment methodology has been implemented into a map-based tool to automatically assess expected impacts of volcanic eruptions based on real ash dispersal and air traffic data. Results of the vulnerability and impact assessment can support the stakeholders involved in the definition of risk-management strategies. Contributions of this research have been applied to case-studies and specific results have been published in a collection of journal papers. Main outcomes of the research are discussed identifying further work to be done in this rapidly evolving field. This research provides useful insights to reduce impacts of volcanic eruptions on civil aviation and, eventually, on the whole society. En Abril 2010, la erupción del volcán Islandés Eyjafjallajokull causó la interrupción mas grande del tráfico aéreo en Europa desde la segunda guerra mundial. A pesar de su baja intensidad, esta erupción produjo una nube de ceniza que cubrió Europa central causando la cancelación de mas de 100.000 vuelos y perdidas económicas de más de 1.700 millones de USD. Este evento generó muchas preguntas en la opinión publica y las comunidades impactadas. ¿Pero cómo pudo una erupción volcánica provocar impactos tan fuertes a escala continental? ¿Fueron estos impactos realmente inesperados? ¿Qué se habría podido hacer para mejorar la preparación de la aviación civil? Los daños que la ceniza volcánica puede provocar en los componentes de los aviones se han documentado desde los años ochenta. También, gracias a sofisticados modelos numéricos desarrollados en las ultimas décadas, los patrones de dispersión de ceniza volcánica se pueden pronosticar. Aun así, la erupción de Eyjafjallajokull en 2010 evidenció que la sociedad no estaba preparad a lidiar con este tipo de eventos y sus impactos directos e indirectos. En Europa los procedimientos a seguir en caso de ceniza volcánica en el espacio aéreo se habían aplicado en pocas ocasiones, debido a la frecuencia relativamente baja de erupciones volcánicas explosivas. Las dificultades sufridas por los gestores del trafico aéreo en 2010 subrayan algunos aspectos a mejorar para mitigar impactos similares en el futuro. Estos aspectos son el punto de partida de esta investigación, que tiene como objetivo ofrecer nuevos métodos para mejorar la gestión del tráfico aéreo durante erupciones volcánicas explosivas. Este documento describe las contribuciones desarrolladas durante los 4 años de investigación pre-doctoral. Esta investigación propone algunas mejoras en las estrategias de modelado utilizadas actualmente para dispersión de ceniza en la atmósfera, y generar resultados que satisfagan las necesidades de la aviación civil. Se presenta la primera metodología que permite estimar la vulnerabilidad del trafico aéreo en caso de erupciones volcánicas y los impactos de la ceniza volcánica sobre sus elementos. También se ha creado una herramienta informática que permite automatizar el análisis de impactos y producir resultados utilizando datos reales de dispersión de ceniza y de trafico aéreo. Este documento discute los resultados principales de la investigación y propone directrices para su desarrollo futuro. Las contribuciones de esta investigación se han aplicado a varios casos de estudio para producir resultados específicos, y se pueden potencialmente aplicar a otras zonas. Los resultados se han presentado y discutido en un compendio de artículos científicos, publicados en revistas internacionales. Los análisis de vulnerabilidad e impacto pueden dar soporte a los actores involucrados en la gestión de trafico aéreo y la definición de estrategias para la gestión de riesgo. Sus resultados son significativos para dar soporte y definir estrategias para la gestión de riesgo. Los desarrollos futuros de esta investigación podrían utilizarse para reducir el impacto de erupciones volcánicas sobre la aviación civil, que afectan indirectamente a toda la sociedad

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Olgun, Nazlı [Verfasser]. "Impacts of airborne volcanic ash on the surface ocean biogeochemistry and marine ecosystems / Nazlı Olgun." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/1020283823/34.

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Young, Cindy L. "A satellite and ash transport model aided approach to assess the radiative impacts of volcanic aerosol in the Arctic." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53404.

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The Arctic radiation climate is influenced substantially by anthropogenic and natural aerosols. There have been numerous studies devoted to understanding the radiative impacts of anthropogenic aerosols (e.g. those responsible for producing the Arctic haze phenomenon) and natural aerosols (e.g. dust and smoke) on the Arctic environment, but volcanic aerosols have received less attention. Volcanic eruptions occur frequently in the Arctic and have the capacity to be long duration, high intensity events, expelling large amounts of aerosol-sized ash and gases, which form aerosols once in the atmosphere. Additionally, volcanic eruptions deposit ash, which can alter the surface reflectivity, and remain to influence the radiation balance long after the eruptive plume has passed over and dissipated. The goal of this dissertation is to quantify the radiative effects of volcanic aerosols in the Arctic caused by volcanic plumes and deposits onto ice and snow covered surfaces. The shortwave, longwave, and net direct aerosol radiative forcing efficiencies and atmospheric heating/cooling rates caused by volcanic aerosol from the 2009 eruption of Mt. Redoubt were determined by performing radiative transfer modeling constrained by NASA A-Train satellite data. The optical properties of volcanic aerosol were calculated by introducing a compositionally resolved microphysical model developed for both ash and sulfates. Two compositions of volcanic aerosol were considered in order to examine a fresh, ash rich plume and an older, ash poor plume. The results indicate that environmental conditions, such as surface albedo and solar zenith angle, can influence the sign and the magnitude of the radiative forcing at the top of the atmosphere and at the surface. Environmental conditions can also influence the magnitude of the forcing in the aerosol layer. For instance, a fresh, thin plume with a high solar zenith angle over snow cools the surface and warms the top of the atmosphere, but the opposite effect is seen by the same layer over ocean. The layer over snow also warms more than the same plume over seawater. It was found that plume aging can alter the magnitude of the radiative forcing. For example, an aged plume over snow at a high solar zenith angle would warm the top of the atmosphere and layer by less than the fresh plume, while the aged plume cools the surface more. These results were compared with those reported for other aerosols typical to the Arctic environment (smoke from wildfires, Arctic haze, and dust) to demonstrate the importance of volcanic aerosols. It is found that the radiative impacts of volcanic aerosol plumes are comparable to those of other aerosol types, and those compositions rich in volcanic ash can have greater impacts than other aerosol types. Volcanic ash deposited onto ice and snow in the Arctic has the potential to perturb the regional radiation balance by altering the surface reflectivity. The areal extent and loading of ash deposits from the 2009 eruption of Mt. Redoubt were assessed using an Eulerian volcanic ash transport and dispersion model, Fall3D, combined with satellite and deposit observations. Because observations are often limited in remote Arctic regions, we devised a novel method for modeling ash deposit loading fields for the entire eruption based on best-fit parameters of a well-studied eruptive event. The model results were validated against NASA A-train satellite data and field measurements reported by the Alaska Volcano Observatory. Overall, good to moderate agreement was found. A total cumulative deposit area of 3.7 X 10^6 km2 was produced, and loadings ranged from ~7000 ± 3000 gm-2 near the vent to <0.1 ± 0.002 gm-2 on the outskirts of the deposits. Ash loading histories for total deposits showed that fallout ranged from ~5 – 17 hours. The deposit loading results suggest that ash from short duration events can produce regionally significant deposits hundreds of kilometers from the volcano, with the potential of significantly modifying albedo over wide regions of ice and snow covered terrain. The solar broadband albedo change, surface radiative forcing, and snowmelt rates associated with the ash deposited from the 2009 eruption of Mt. Redoubt were calculated using the loadings from Fall3D and the snow, ice, and aerosol radiative models. The optical properties of ash were calculated from Mie theory, based on size information recovered from the Fall3D model. Two sizes of snow were used in order to simulate a young and old snowpack. Deposited ash sizes agree well with field measurements. Only aerosol-sized ashes in deposits were considered for radiative modeling, because larger particles are minor in abundance and confined to areas very close to the vent. The results show concentrations of ash in snow range from ~ 6.9x10^4 – 1x10^8 ppb, with higher values closer to the vent and lowest at the edge of the deposits, and integrated solar albedo reductions of ~ 0 – 59% for new snow and ~ 0 – 85% for old snow. These albedo reductions are much larger than those typical for black carbon, but on the same order of magnitude as those reported for volcanic deposits in Antarctica. The daily mean surface shortwave forcings associated with ash deposits on snow ranged from 0 – 96 Wm-2 from the outmost deposits to the vent. There were no significantly accelerated snowmelts calculated for the outskirts of the deposits. However, for areas of higher ash loadings/concentrations, daily melt rates are significantly higher (~ 220 – 320%) because of volcanic ash deposits.

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Moore, Oliver. "Chemical weathering of volcanic rocks in the tropics : using small scale studies to determine the mechanisms, rates and impacts of perturbations." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738514.

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Kleinschmitt, Christoph. "Climate engineering with stratospheric sulphate aerosol : development and application of a global atmosphere-aerosol model for studying potential efficacy and impacts." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066560/document.

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L'augmentation artificielle de la couche stratosphérique d'aérosol de sulfate a été proposée comme méthode pour réduire le réchauffement climatique causé par les émissions anthropiques de gaz à effet de serre. Dans cette thèse, nous présentons un modèle global atmosphère-aérosol nouvellement développé, évaluons sa performance par rapport aux observations et l'appliquons pour étudier l'efficacité et les impacts de cette forme possible d'ingénierie climatique. Nous trouvons que l'effet de refroidissement réalisable par unité de masse de soufre injectée peut diminuer de façon plus drastique qu'estimé précédemment pour des taux d'injection élevés et que des injections à plus haute altitude ou dans des régions plus grandes n'entraînent pas un refroidissement plus fort. L'efficacité de la méthode pourrait donc être plutôt limitée, tout au moins dans les cas d'injections tropicales de dioxyde de soufre que nous avons modélisées. Par ailleurs, il existe plusieurs effets secondaires potentiellement nocifs, tels que le chauffage stratosphérique dû à l'absorption de rayonnement par l'aérosol provoquant de fortes perturbations dans la dynamique atmosphérique, la composition chimique de la stratosphère et les nuages hauts. Enfin, nous trouvons que les effets radiatifs de l'injection d'aérosol stratosphérique et de l'éclaircissement des nuages marins, une autre technique de géo-ingénierie proposée, seraient largement additifs et complémentaires lors de leur application parallèle. Cela pourrait permettre de concevoir un port-folio d'approches pour atteindre des objectifs climatiques spécifiques et réduire les effets secondaires indésirables de l'ingénierie climatique The enhancement of the stratospheric sulphate aerosol layer has been proposed as a method to abate the global warming caused by anthropogenic greenhouse gas emissions. In this thesis we present a newly developed global atmosphere-aerosol model, evaluate its performance against observations, and apply it to study the effectiveness and impacts of this possible form of climate engineering. We find that the achievable cooling effect per injected sulphur mass unit may decrease more drastically for larger injections than previously estimated and that injections at higher altitude or over larger areas do not result in a stronger cooling. The effectiveness of the method may therefore be rather limited, at least when using tropical injections of sulphur dioxide as in our model experiments. In addition, there are several potentially harmful side effects, such as stratospheric heating due to absorption of radiation by the aerosol causing strong perturbations in atmospheric dynamics, composition, and high-level clouds. Furthermore, we find that the radiative effects of stratospheric aerosol injection and marine cloud brightening, another proposed geoengineering technique, would be largely additive and complementary when applying them together. This might allow the design of portfolio approaches to achieve specific climate goals and reduce unintended side effects of climate engineering

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Picquout, Adrien. "Impacts géographiques de l'éruption de 2010 du volcan Merapi, Java, Indonésie." Thesis, Paris 1, 2013. http://www.theses.fr/2013PA010581/document.

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Le 26 octobre 2010, le Merapi, volcan le plus peuplé et le plus actif de l'île de Java en Indonésie, est entré en éruption. Depuis plusieurs mois, l'activité du volcan avait crû de manière exponentielle et les scientifiques s'attendaient à une éruption exceptionnelle. Leurs pronostics furent confirmés puisqu'un blast parcourut une distance de 8 km, rasa en partie deux villages évacués, et tua mbah Marijan, le « gardien des clés du volcan » et son entourage, ce qui perturba l'équilibre culturel de la région. Dans les jours suivants, l'activité du volcan continua de s'intensifier et des évacuations massives furent organisées. L'éruption paroxysmale du Merapi eut lieu dans la nuit du 4 au 5 novembre ; alors que plusieurs dizaines de milliers de villageois étaient en train de fuir le volcan, de puissantes coulées pyroclastiques dévastèrent les flancs du volcan, tuant et détruisant tout sur leur passage sur une distance maximale de 17 km. Cette nuit-là, plus de 250 personnes furent tuées et des milliers d'autres blessées. Le secteur agricole subit de lourdes pertes puisque de nombreuses récoltes et un grand nombre de têtes de bétail furent perdus. L'activité touristique de la région connut une réaction en chaîne d'impacts, générée en grande partie par la fermeture de l'aéroport de Yogyakarta. La thèse propose de faire une étude transversale et systémique de ces impacts en analysant comment gouvernement et populations se remettent de cette éruption et s'apprêtent à faire face à une future crise causée par le Merapi On October 26th 2010, the Merapi volcano, the most populated and active volcano on the Java Island in Indonesia, began erupting. During several months, the volcano's activity grew exponentially and scientists were expecting an exceptional eruption. Their predictions got confirmed as a blast ran through a distance of 8 km, partially destructed two villages (that got evacuated) and killed mbah Marijan, the « Volcano's keys guardian » and his entourage. As a consequence, the cultural balance of the region got disrupted for a while. In the following days, the volcano's activity kept increasing and mass evacuations were organized. The paroxysmal eruption of Merapi occurred in the night of November 4th to 5th 2010, while tens of thousands of villagers were running away from the volcano. Powerful pyroclastic flows ran down its flanks, killing and destroying everything on their way over a maximum distance of 17 km. During that night, over 250 people were killed and thousands were injured. The agricultural sector suffered from heavy losses as many crops and livestock were lost. The tourism industry in the region experienced a chain reaction of impacts generated by the closure of Yogyakarta airport. The thesis offers to make a transversal and systemic study of these impacts by analyzing how the government and people recovered from the eruption and how they are to face a future crisis caused by the Merapi

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Kleinschmitt, Christoph. "Climate engineering with stratospheric sulphate aerosol : development and application of a global atmosphere-aerosol model for studying potential efficacy and impacts." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066560.

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Abstract:

L'augmentation artificielle de la couche stratosphérique d'aérosol de sulfate a été proposée comme méthode pour réduire le réchauffement climatique causé par les émissions anthropiques de gaz à effet de serre. Dans cette thèse, nous présentons un modèle global atmosphère-aérosol nouvellement développé, évaluons sa performance par rapport aux observations et l'appliquons pour étudier l'efficacité et les impacts de cette forme possible d'ingénierie climatique. Nous trouvons que l'effet de refroidissement réalisable par unité de masse de soufre injectée peut diminuer de façon plus drastique qu'estimé précédemment pour des taux d'injection élevés et que des injections à plus haute altitude ou dans des régions plus grandes n'entraînent pas un refroidissement plus fort. L'efficacité de la méthode pourrait donc être plutôt limitée, tout au moins dans les cas d'injections tropicales de dioxyde de soufre que nous avons modélisées. Par ailleurs, il existe plusieurs effets secondaires potentiellement nocifs, tels que le chauffage stratosphérique dû à l'absorption de rayonnement par l'aérosol provoquant de fortes perturbations dans la dynamique atmosphérique, la composition chimique de la stratosphère et les nuages hauts. Enfin, nous trouvons que les effets radiatifs de l'injection d'aérosol stratosphérique et de l'éclaircissement des nuages marins, une autre technique de géo-ingénierie proposée, seraient largement additifs et complémentaires lors de leur application parallèle. Cela pourrait permettre de concevoir un port-folio d'approches pour atteindre des objectifs climatiques spécifiques et réduire les effets secondaires indésirables de l'ingénierie climatique The enhancement of the stratospheric sulphate aerosol layer has been proposed as a method to abate the global warming caused by anthropogenic greenhouse gas emissions. In this thesis we present a newly developed global atmosphere-aerosol model, evaluate its performance against observations, and apply it to study the effectiveness and impacts of this possible form of climate engineering. We find that the achievable cooling effect per injected sulphur mass unit may decrease more drastically for larger injections than previously estimated and that injections at higher altitude or over larger areas do not result in a stronger cooling. The effectiveness of the method may therefore be rather limited, at least when using tropical injections of sulphur dioxide as in our model experiments. In addition, there are several potentially harmful side effects, such as stratospheric heating due to absorption of radiation by the aerosol causing strong perturbations in atmospheric dynamics, composition, and high-level clouds. Furthermore, we find that the radiative effects of stratospheric aerosol injection and marine cloud brightening, another proposed geoengineering technique, would be largely additive and complementary when applying them together. This might allow the design of portfolio approaches to achieve specific climate goals and reduce unintended side effects of climate engineering

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Assbichler, Donjá [Verfasser], and Thomas [Akademischer Betreuer] Kunzmann. "Impact of CO2 on alkali-rich explosive volcanism : case studies from Saray Volcano, Iran and Laacher See Volcano, Germany / Donjá Assbichler ; Betreuer: Thomas Kunzmann." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1221062093/34.

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Schneider, Lea [Verfasser]. "Climatic impact of volcanic eruptions over the past millennium / Lea Schneider." Mainz : Universitätsbibliothek Mainz, 2017. http://d-nb.info/1133216919/34.

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16

Zhu, Zihang. "Study of volcanic ash impact onto turbine blades in jet engines." Thesis, University of Surrey, 2019. http://epubs.surrey.ac.uk/850038/.

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Gas turbines are of great importance in industry. In the turbine section within a jet engine, thermal barrier coatings (TBCs) are utilized to protect the metal turbine blades, thus improve the efficiency of engine. However, this coating is extremely vulnerable to attack by injected particulates. This ingested particulate is often referred to as "CMAS" (Calcia-Magnesia-Alumina-Silica). Among all the CMAS materials, Volcanic Ash (VA) is the most common type which aeroengines may encounter during the flight. This type of CMAS material would melt in the combustion section by ultra high temperature and then impact the turbine blades with relatively high speed. Some of the particles would then stick on and bond with the TBC, thus cause degradation of the protecting coating. In this way, the jet engine would be permanently damaged. In the recent years, experiments have been done by different researchers to elaborate the effect of CMAS materials on TBCs. However, there is still a lack of knowledge in the bonding mechanism and physical adhesion between the CMAS particles (especially VA particles) and the substrate. A study of VA particle impingement is required in order to understand particle impingement, phase transition and heat transfer, bonding mechanism and splat morphology in detail. In this research, experiments were carried at Cambridge University, by Prof. Trevor William Clyne, Dr. James Dean and Dr. Catalina Taltavull to reproduce the VA-substrate impingement in jet engine. A Vacuum Plasma Spray (VPS) system was utilized to create a high-temperature, high-velocity flow field. Different types of Volcanic Ashes (VAs) were introduced into the experimental set-up. Sticking rate, Scanning Electron microscope (SEM) micrographs of deposition morphology were examined and collected. Chapter 3 elaborates the details of this experiment set-up and data collected from the experiment. This experiment set-up is utilized by the author for building numerical models and the result of this experiment is used to validate the numerical models. Three numerical models were built to perform a systematic study. Firstly, in Chapter 4, a Computational Fluid Dynamic (CFD) model was created to simulate the steady-state of the VPS flow field. The Discrete Particle Method (DPM) model was then utilized to simulate the injection of volcanic ash particles. After calculating the BI number, non-isothermal effects within the ceramic particles were simulated by introducing the heat transfer function by a user-defined function (UDF). This model gives the temperature gradient within and velocity of the in-flight VA particles at any time during the spray. It is shown that small particles (diameter < $10\ \mu m$) would easily be melted and reach the iso-thermal state. However, these particles would be largely influenced by the flow field thus bypass the turbine blades. The large particles (diameter > $50\ \mu m$) would easily impact the turbine blades, but would remain unmelted due to the large grain size. It is concluded that VA particles with diameter of $15\ \mu m$ to $40\ \mu m$ are the most "dangerous" particles, because these particles have both relatively high possibility to be melted, and high possibility to impact thus adhere on the substrate. Second of all in Chapter 5, systematic study of Yttria-stabilized Zirconia (YSZ) particle impingement and deposition on stainless steel in thermal spray process has been performed. A Coupled Eulerian and Lagrangian model was developed. This model contributes to simulate the process of semi-molten particle impact. By utilizing this model, both the large deformation of liquid part and the plastic deformation of the solid part could be extracted. One fully molten and two semi-molten(solid core with liquid shell and solid shell with liquid core) cases were studied. The results of the numerical model matches well with the experiment and analytical data. Interest parameters such as velocity, temperature, fraction of liquid part were varied. The contact area, splat morphology and local contact temperature were collected and studied. It is shown that, the larger the liquid fraction is, the larger the contact area would be. Moreover, effect of roughness of substrate is also studied. It is suggested that substrate roughness whose average asperity size is higher than the 1/10 of particle size is beneficial for adhesion. Third of all in Chapter 6, in order to simulate the impact for high-viscosity glass-state ceramic particles, Smoothed Particle Hydrodynamic (SPH) model was built. For high/ultra viscosity cases, traditional CFD method and Finite Element Method (FEM) would be extremely slow. SPH model transfers the Eulerian equations into Lagrangian equations. By utilizing this method, computational resources could be saved, and high viscosity impact could be simulated. The SPH algorithm was coded and equations for heat transfer was introduced to simulate the solidification of liquid. Systematic study were performed by utilizing this model. Viscosity, contact angle, velocity of particles were varied. Contact area, splat morphology and solidification at the contact area were examined. It is shown that, large contact angle would result in large contact area. However, particles impingement with low viscosity and high contact angle could result in the break up of the particles. The similar phenomena could be seen in experiment - small particles have lower viscosity and are approaching the substrate with a large contact angle. Therefore, the deposition of these types of particles show an obvious evidence of break up and oblique impact.

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17

Lamur, A. L. "Development, impact and longevity of fractures in magmatic, volcanic and geothermal systems." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3019206/.

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The migration of fluids in the Earth’s crust embodies the last stage of the internal heat release of our planet. Either spectacularly expressed at the surface through volcanic activity, or more subtly as internal hydrothermal circulation, this phenomenon involves the upwards motion of fluids and magmas that contribute to more efficient heat transfer. On one hand, volcanic eruptions result from the movement of buoyant magmatic liquids towards the surface. On their way up, these magmas cool down, crystallise and upon decompression, build up an internal pressure that dictate the eruptive style: Effusive when the internal pressure is released as it builds up; explosive when the internal pressure accumulates until it is able to fracture the magma. In nature, the shift from effusive to explosive activity is often periodic, reflecting cycles of pressure accumulation and relaxation in the conduit. On the other hand, hydrothermal circulation results from the infiltration of water, of meteoric or magmatic origin, into the rocks making up the crust. Higher temperatures at depth and/ or due to the presence of a magmatic body, trigger the formation of convective cells in which chilled, denser water percolates downwards then heats up, losing density before moving back upwards. Importantly, the circulation of both hydrothermal fluids and magmatic liquids is controlled by the presence of fractures in the crust and the permeability of the surrounding rocks. In this thesis, I first investigate how fractures affect the localisation of fluids in fractured porous rocks through permeability measurements, both at atmospheric pressure and at shallow confining conditions (< 30 MPa; ~1 km depth). I demonstrate that the impact of fractures is greater at lower porosities as the permeability is greatly increased. In more porous rocks, higher pore connectivity means that macro-fractures affect the permeability less significantly, as at least some of the fluid flows through the pre-existing connected porous network. I further demonstrate that, during confinement, most of the mechanical closure occurs at shallow conditions (< 5 MPa; ~200m depth) for the porosity range tested. In addition, I show that mechanically shutting a fracture does not seal the permeable pathways, and that the fractured system is unable to retrieve the same permeability as the intact system. I then develop an analytical solution for the permeability of variably porous, fractured systems as a function of depth before numerically solving it. I complement this work with two “case studies” in which tensile fractures form and open or heal, and link this to the system permeability evolution through time and the implications for magmatic, volcanic and geothermal systems. In the first scenario, tensile fractures open in a cooling magmatic body to form columnar joints in a basalt. Because the temperature at which cooling joints form remains elusive, causing a lingering scientific debate, I develop a novel type of mechanical testing and show for the first time that, in basaltic systems, these macro-fractures form purely in the elastic regime. This is further supported by the use of the rock’s thermo-mechanical characteristics (namely thermal expansion and tensile strength) to model the tensile stress build-up upon cooling and, once formed, the evolution of the fracture width between two columns. Applying the analytical solution for fractured systems permeability defined earlier, I further model the permeability evolution of a columnar jointing magmatic body, important for the understanding of fluid migration during drilling close to magmatic chambers. Finally, in magmas, the entrapment of exsolving gases, during ascent, force the accumulation of stress in the liquid, building pore pressure and potentially resulting in magmatic fragmentation. Consequently, the accumulated stresses can then be dissipated at times longer than the relaxation timescale of the melt, allowing fractures to heal and the system to recover strength lose permeability. Using synthetic glasses in a newly designed experimental setup, I show that the time required to start the healing process is proportional to the relaxation timescale of the melt. I further demonstrate that the kinetics of fracture healing involve two distinct stages. The first stage sees the fracture walls viscously deforming to dissipate excessive energy along the fracture plane (wetting regime), while the second stage consists of the diffusive exchange of elements across the fracture interface (diffusive regime). I finally surmise that the cyclic activity of persistently active silicic volcanoes could be explained by dynamic permeability and strength variations of material due to repeating fracture and healing cycles. Overall, I show that the development and longevity of fractures have significant impacts on the localisation of fluid flow, highlighting that fractures significantly contribute to the development of anisotropy in magmatic, volcanic and geothermal environments. A better understanding of the longevity of fractures in these systems is of prime importance in the mitigation of hazards associated to volcanic eruptions, but also in the development of cheaper, more efficient geothermal energy.

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Poret, Matthieu <1989&gt. "Modelling ash cloud dispersion and the impact of ash aggregation during volcanic eruptions." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8633/1/Poret_Matthieu_Tesi_Revised.pdf.

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Improvements for characterizing eruption processes are made commonly through field or remote-sensing measurements, lab experiments and numerical models. However, the main volcanological parameters inter-dependency makes challenging the assessment of tephra dispersion and sedimentation, from which mass eruption rate, total erupted mass, and Total Grain-Size Distribution (TGSD) are typically estimated. This thesis aims at better constraining Eruption Source Parameters (ESP) and in particular the TGSD, usually derived from field sample analysis. The estimation of very fine ash (i.e. < 30 μm) fraction, within the TGSD, commonly suffers from the lack of distal field data, especially for basaltic eruptions. Besides, particle-particle aggregation affects ash dispersal and deposition. Although numerical simulations can account for ash aggregation, they need an accurate TSGD as input. Here, I report the use of the FALL3D model with airborne and ground-based data to quantify i) the very fine ash and the effect on the results and ii) the occurrence of ash aggregation during ash transport. I focus on the integration of field and satellite data to better estimate the TGSD and the PM10 fraction especially. The methodology, which integrates field, ground-based and satellite measurements to improve the TGSD characterization, is applied first to the 23rd February 2013 Etna paroxysm, then to the 23rd November 2013 Etna eruption. Indeed, these eruptions benefited from south-westerly winds dispersing tephra towards the Puglia region (southern Italy; ~410 km from the source), allowing collection of field samples to very distal areas. Then, I studied ash aggregation processes characterizing the explosive eruption of La Soufrière Saint Vincent on 26th April 1979. During this event, a significant aggregate fraction was observed contributing to premature tephra fallout from the vent to Bequia Island (36 km southwards). I investigated the effect of various TGSD together with different aggregation schemes on the resulting tephra loading and ash dispersal.

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Fitzgerald, Rebecca Hanna. "An assessment of ballistic hazard and risk from Upper Te Maari, Tongariro, New Zealand." Thesis, University of Canterbury. Department of Geological Sciences, 2014. http://hdl.handle.net/10092/9581.

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Explosive volcanic eruptions frequently expel ballistic projectiles, producing a significant proximal hazard to people, buildings, infrastructure and the environment from their high kinetic and thermal energies. Ballistic hazard assessments are undertaken as a risk mitigation measure, to determine probabilities of eruptions occurring that may produce ballistics, identify areas and elements likely to be impacted by ballistics, and the potential vulnerabilities of elements to ballistics. The 6 August, 2012 hydrothermal eruption of Upper Te Maari Crater, Tongariro, New Zealand ejected blocks over a 6 km2 area, impacting ~2.6 km of the Tongariro Alpine Crossing (TAC), a walking track hiked by ~80,000 people a year, and damaging an overnight hut along the track. In this thesis ballistic hazard and risk from Upper Te Maari Crater are assessed through a review of its eruptive history, field and orthophoto mapping of the 6 August ballistic impact distribution, forward modelling and analysis of possible future eruption scenarios using a calibrated 3D ballistic trajectory model, and analysis of the vulnerability of hikers along the impacted Tongariro Alpine Crossing. Orthophoto mapping of the 6 August ballistic impact crater distribution revealed 3,587 impact craters with a mean diameter of 2.4 m. However, field mapping of accessible regions indicated an average of at least four times more observable impact craters and a smaller mean crater diameter of 1.2 m. By combining the orthophoto and ground-truthed impact frequency and size distribution data, it is estimated that approximately 13,200 ballistic projectiles were generated during the eruption. Ballistic impact distribution was used to calibrate a 3D ballistic trajectory model for the 6 August eruption. The 3D ballistic trajectory model and a series of inverse models were used to constrain the eruption directions, angles and velocities. When combined with eruption observations and geophysical observations and compared to the mapped distribution, the model indicated that the blocks were ejected in five variously directed eruption pulses, in total lasting 19 seconds. The model successfully reproduced the mapped impact distribution using a mean initial particle velocity of 200 m/s with an accompanying average gas flow velocity over a 400 m radius of 150 m/s. Assessment of the vulnerability of hikers to ballistics from the August eruption along the TAC utilised the modelled spatial density of impacts and an assumption that an average ballistic impact will cause serious injury or death (casualty) over an 8 m2 area. It is estimated that the probability of casualty ranged from 1% to 16% along the affected track (assuming an eruption during the time of exposure). Future ballistic hazard and vulnerability along the TAC are also assessed through application of the calibrated model. A magnitude larger eruption (than the 6 August) in which 10x more particles were ejected, doubled the affected length of the TAC and illustrated that the probability of casualty could reach 100% in localised areas of the track. In contrast, ballistics ejected from a smaller eruption did not reach the track as was the case with the 21 November 2012 eruption. The calibrated ballistic model can therefore be used to improve management of ballistic hazards both at Tongariro and also, once recalibrated, to other volcanoes worldwide.

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20

Raschke, Ulli [Verfasser]. "The El’gygytgyn impact structure, Siberia: Impactites from a mid-size impact structure in volcanic target rocks / Ulli Raschke." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1140487086/34.

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21

Peers, Justin. "A Systematic Assessment of Socio-Economic Impacts of Prolonged Episodic Volcano Crises." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etd/3580.

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Uncertainty surrounding volcanic activity can lead to socio-economic crises with or without an eruption as demonstrated by the post-1978 response to unrest of Long Valley Caldera (LVC), CA. Extensive research in physical sciences provides a foundation on which to assess direct impacts of hazards, but fewer resources have been dedicated towards understanding human responses to volcanic risk. To evaluate natural hazard risk issues at LVC, a multi-hazard, mail-based, household survey was conducted to compare perceptions of volcanic, seismic, and wildfire hazards. Impacts of volcanic activity on housing prices and businesses were examined at the county-level for three volcanoes with a “very high” threat designation from the U.S. Geological Survey (USGS); LVC, (caldera system), Mount St. Helens, WA (stratovolcano), and Kīlauea, HI (shield volcano). A negative relationship was found between volcanic risk perception and preparedness. Additionally, the perception that housing prices declined after volcano alerts was confirmed by econometric modeling.

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22

Grattan, John Patrick. "The impact of Icelandic volcanic eruptions upon the ancient settlement and environment of northern and western Britain." Thesis, University of Sheffield, 1995. http://etheses.whiterose.ac.uk/14822/.

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Percival, Lawrence. "Exploring the use of mercury in reconstructing the environmental impacts of Large Igneous Provinces." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:eb84e4a0-5229-405b-8c8d-a015f601ca39.

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Large Igneous Provinces (LIPs) represent geologically rapid emplacements of vast quantities of igneous material into/onto Earth's crust. There is a marked correlation in the known ages of LIPs and Mesozoic extinctions and other environmental perturbations, suggesting a possible causal link between these events. However, uncertainties in matching LIP basalt ages to the stratigraphic record of Mesozoic events mean that a sedimentary tracer of volcanism would better indicate a precise coincidence between the two phenomena. Mercury (Hg) has shown potential as such a proxy. Volcanism is a major source of Hg to the natural environment, and its relatively long atmospheric residence time (0.5â2 years) allows global distribution of the element before it is deposited to sediments. However, questions remain about how the manner of LIP emplacement might influence its impact on the Hg cycle, as well as how sedimentary processes may locally overprint any global signal. Here, the Hg records of three Mesozoic events are investigated: the end-Triassic extinction (TJ: ~201.5 Ma), Cretaceous Oceanic Anoxic Event 2 (OAE 2: ~94 Ma), and the latest Cretaceous (KâPg: ~67â66 Ma). These events coincided with markedly different LIPs: OAE 2 with multiple submarine LIPs; the KâPg and TJ with subaerial LIPs; with the TJ also featuring release of additional thermogenic volatiles from intrusion of organic-rich lithologies by LIP sills. Additionally, mercury is used with osmium and carbon isotopes to study the temporal relationships between volcanism, weathering, and the carbon cycle during the Toarcian Oceanic Anoxic Event (~183 Ma). This work highlights the links between LIP volcanism and other surface processes, and shows that subaerial LIPs featuring thermogenic emissions are most likely to perturb the global Hg cycle, with the record of such perturbations dependent on the nature of the sedimentary archive.

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Namiki, Noriyuki. "Tectonics and volcanism on Venus : constraints from topographic relief, impact cratering, and degassing." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/55042.

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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 &permil;) 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 δ15N data range (-6 to +1 &permil;) 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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Geisen, Carla. "Macro- and micronutrient dissolution from desert and volcanic aerosols in rain and seawater : impact on phytoplankton in the Southern Indian Ocean." Electronic Thesis or Diss., Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS151.pdf.

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Les aérosols constituent une source importante de macro- et micronutriments pour l’océan hauturier. Cependant, uniquement les nutriments dissous sont considérés comme biodisponibles, c’est-à-dire assimilables par le phytoplancton. Ainsi, la quantification de leur solubilité se révèle primordiale pour (i) estimer l’influence d’un dépôt d’aérosols sur le phytoplancton, et (ii) boucler les cycles biogéochimiques de ces éléments. Dans le cadre de cette thèse, nous avons établi des gammes de solubilité de deux types d’aérosols (désertique ou volcanique) selon le mode de dépôt (sec et humide), en intégrant la variabilité en fonction de l’origine des aérosols. Ainsi, le macronutriment silicium issu des poussières désertiques est plus soluble comparé aux cendres volcaniques (jusqu’à 0.7 % contre 0.2 %), notamment via la dissolution du quartz. Le micronutriment fer se dissout majoritairement dans l’eau de pluie lors d’un dépôt humide des aérosols à l’océan via la dissolution d’aluminosilicates, avec une solubilité généralement inférieure à 0.14 % et 0.02 %, dans l’eau de pluie et eau de mer respectivement, et ce indépendamment du type d’aérosol. L’ensemble de ces résultats permet ainsi une révision des flux de nutriments atmosphériques à l’océan de surface qui pourra être in fine intégrée dans les estimations globales de modélisation biogéochimique. La réponse biologique suite à un apport de nutriments par voie atmosphérique a été déterminée dans l’Océan Indien Austral et les nutriments ont majoritairement profité à la communauté de diatomées, notamment au niveau du plateau de Kerguelen Aerosols are an important source of macro- and micronutrients for the open ocean. However, only dissolved nutrients are considered bioavailable, i.e. assimilable by phytoplankton. Thus, the quantification of their solubility is essential to (i) estimate the influence of aerosol deposition on phytoplankton, and (ii) closing the biogeochemical cycles of these elements. We thus established the solubility ranges of two types of aerosols (desert or volcanic) according to the deposition mode (dry and wet), by integrating the variability depending on the aerosol origin. Thus, the macronutrient silicon found in desert dust is more soluble compared to volcanic ash (up to 0.7 % against 0.2 %), in particular via the dissolution of quartz. The micronutrient iron dissolves mainly in rainwater during wet deposition of aerosols in the ocean via the dissolution of aluminosilicates, with solubilities generally below 0.14% and 0.02%, in rainwater and seawater respectively, regardless of the type of aerosol. Thus, these results allow a re-estimation of atmospheric nutrients fluxes to the surface ocean which could ultimately be integrated into global biogeochemical models. Finally; the biological response to an atmospheric nutrient input has been determined in the Southern Indian Ocean and the nutrients have mainly benefited the diatom community, especially at the Kerguelen plateau

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Alves, Ana. "Impact de l’éruption du volcan Toba sur le climat et la dynamique océan-atmosphère." Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS060.pdf.

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Les éruptions volcaniques explosives tropicales, surtout si elles sont de nature stratosphérique, sont des phénomènes naturels qui peuvent influencer de manière significative le climat. Ce sont les émissions de soufre vers l'atmosphère qui jouent un rôle majeur. En effet, ce gaz précurseur d'aérosols, peut d'une part engendrer une modification de la température en diminuant le rayonnement solaire incident, et d'autre part, perturber la chimie des océans. L'éruption du volcan Toba (Younger Toba Tuff, YTT), s'est produite il y ~74 000 ans sur l'ile de Sumatra. Elle est actuellement considérée comme la plus grande éruption du Quaternaire. Ses émissions vers l'atmosphère sont estimées entre 3.5 x 1010 et 3.3 x 1012 kg de soufre, et ~8600 km3 de cendres qui se sont réparties sur près de ~40 millions de km2. De nombreuses incertitudes sur les paramètres clés de l'éruption (durée, dynamique éruptive, émissions) persistent et rendent difficile l'estimation de son impact sur le climat. Cependant, certaines études ont suggéré que l'éruption du Toba aurait eu un impact sur la mousson indienne. L'hypothèse est que le refroidissement global causé par les aérosols d'origine volcanique a pu altérer les gradients de température de surface et perturber la circulation atmosphérique et les vents de mousson. Cette thèse a pour objectif de (1) reconstruire la variabilité de la mousson indienne lors des derniers 150 000 ans, (2) étudier à très haute résolution la transition entre le stade isotopique marin 5 (interglaciaire) et le stade 4 (glaciaire) afin d'observer l'impact de l'éruption du Toba sur l'océan de surface et la dynamique océan-atmosphère. Pour réaliser cette étude, un analyse multi-proxy (isotopes du bore (δ11B) et de l'oxygène (δ18O), rapport Mg/Ca des foraminifères G. ruber, fluorescence de rayons X (XRF) et abondance des foraminifères G.bulloides et G. ruber) a été réalisée sur deux carottes marines provenant de l'océan Indien tropical. La carotte BAR94-25 a été prélevée en mer d'Andaman (~600 km du volcan Toba) et la carotte MD00-2355 en mer d'Arabie (~4500 km). Ces carottes sont idéalement situées dans deux régions fortement influencées par la mousson indienne. Plusieurs niveaux de téphra appartenant au volcan Toba ont été identifiés dans ces deux carottes et correspondent à plusieurs événements explosifs pendant la transition climatique MIS5-MIS4. Nos résultats ont montré que lors des dernier 150 000 ans, les variations de la salinité en mer d'Andaman sont en phases avec l'insolation d'automne à 6°N. Ceci a été interprété comme une influence de « El Niño-oscillation australe » (ENSO) et du dipôle de l'océan Indien (DOI) sur le régime de précipitations. En mer d'Arabie, nous avons observé une variabilité glaciaire-interglaciaire de la mousson indienne, avec un affaiblissement de la mousson d'été (Sud-Ouest) en période glaciaire.L'étude détaillé de la transition MIS 5/4 a mis en évidence une acidification de l'océan de surface en mer d'Andaman qui coïncide avec l'activité éruptive du volcan Toba. Nous avons également observé une augmentation graduelle de la salinité qui témoigne d'une diminution des précipitations dans cette région. Ainsi, l'activité volcanique du Toba aurait perturbé la circulation atmosphérique caractérisée par un état moyen semblable à El Niño et à un DOI-. En mer d'Arabie, nos résultats ont permis de voir que l'activité éruptive du volcan Toba a diminué, voire arrêté, la mousson d'été (Sud-Ouest) Tropical explosive volcanic eruptions, especially the stratospheric ones, are natural phenomena that can have a significant influence on climate. Sulfur emissions into the atmosphere play a major role. This aerosol-precursor gas can both modify temperatures by reducing incident solar radiation, and disrupt ocean chemistry. The eruption of the Toba volcano (Younger Toba Tuff, YTT) occurred ~74,000 years ago on the island of Sumatra. It is currently considered the largest eruption of the Quaternary period. Its emissions of material into the atmosphere are estimated at between 3.5 x 1010 and 3.3 x 1012 kg of sulfur and ~8600 km3 of ash spread over nearly ~40 million km2. Numerous uncertainties about the eruption's key parameters (duration, eruptive dynamics, emissions) persist, making it difficult to estimate its impact on climate. However, some studies have suggested that the Toba eruption may have had an impact on the Indian Monsoon. The hypothesis is that the global cooling caused by the release of volcanic aerosols may have altered atmospheric conditions and Monsoon winds. The aim of this thesis is to reconstruct the variability of the Indian Monsoon during the last ice age (150 ka). Then, to study the impact of the Toba eruption on the surface ocean and ocean-atmosphere dynamics, by analyzing at very high resolution the transition between marine isotope stage 5 (interglacial) and stage 4 (glacial). To carry out this study, a multi-proxy analysis (boron (δ11B) and oxygen (δ18O) isotopes, G. ruber Mg/Ca ratio, X-ray fluorescence (XRF) and G.bulloides and G. ruber abundance) was carried out on two marine cores from the tropical Indian Ocean. Core BAR94-25 was taken from the Andaman Sea (~600 km from volcano Toba) and core MD00-2355 from the Arabian Sea (~4500 km). These cores are ideally located in two regions strongly influenced by the Indian Monsoon. Several tephra levels belonging to the Toba volcano were identified in these two cores, corresponding to several explosive events during the MIS5-MIS4 climatic transition. Our results show that during the last 150 ka, salinity variations in the Andaman Sea are in phase with autumn insolation at 6°N. This was interpreted as the influence of El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (DOI) on the precipitation regime. In the Arabian Sea, we observed glacial-interglacial variability of the Indian Monsoon, with a weakening of the summer (southwest) Monsoon during the glacial period. A detailed study of the MIS 5/4 transition revealed acidification of the surface ocean in the Andaman Sea, coinciding with the Toba eruption. We also observed a gradual increase in salinity, reflecting a decrease in precipitation in this region. Thus, the volcanic activity of Toba would have disrupted the atmospheric circulation characterized by a mean state similar to El Niño and a DOI-. In the Arabian Sea, our results showed that the eruption of Toba reduced or even halted the summer Monsoon (Southwest)

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Ettinger, Susanne. "Geomorphological impact of lahars on the southwestern flank of Cotopaxi volcano, Ecuador : drainage system and alluvial fan." Thesis, Clermont-Ferrand 2, 2012. http://www.theses.fr/2012CLF20017.

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Pendant une éruption volcanique sur des sommets englacés, des coulées de débris syn-eruptifs,dénommées lahars, peuvent être générées par la fonte partiale de glaciers. Ce phénomène estbien connu sur le volcan Cotopaxi, Equateur. La présente étude concerne trois vallées et un cônede déjection sur le flanc sud-ouest de ce volcan. Une première analyse a été conduite par relevésde formes géomorphologiques dans ces vallées qui témoignent des processus d’érosion et desédimentation lors du passage de lahars dans le passé, notamment ceux du dernier événementéruptif datant de 1877 AD. Bien que les types des formes géomorphologiques déterminées sontles mêmes, leur distribution spatiale varie d’une vallée à l’autre en fonction d’une interaction deparamètres morphologiques locaux. Les conditions environnementales individuelles déterminentégalement le volume de l’écoulement, paramètre crucial dans la délimitation de zones de risques delahars dans les plaines adjacentes. Pour cela, une deuxième étude a été menée à grande échelle surle cône de déjection à l’exutoire de la vallée la plus au Sud des trois. Une analyse intégrale de la morphologiede surface et des affleurements naturels a été complétée par des données stratigraphiquesde subsurface obtenues via un sondage avec un Géoradar. Reconstituer l’architecture sédimentairede ce cône permet de visualiser la distribution spatiale de formes érosives et de dépôts. L’étude àrévélé que différentes parties du cône sont actives à des moments distincts et les épaisseurs dedépôts de lahars sont variables en fonction du type d’écoulement et de son volume. Ceci permetde relier les dynamiques géomorphologiques des plaines alluviales aux zones d’initiation de laharssur les flancs du volcan. Enfin, cette étude a débouché sur la mise en place d’une nouvelle fonctiondans le logiciel de modélisation de lahars LAHARZ prenant en compte l’incorporation progressive desédiment dans un contexte érosif dans les vallées, ce qui permet une meilleure délimitation de zonesde risque de lahars sur le cône During a volcanic eruption at ice capped volcanoes, syn-eruptive volcanic debris flows, lahars, canbe triggered through the partial melting of the glaciers. This phenomenon is well known to have happenedat Cotopaxi volcano, Ecuador, where the present study has been realized. The latter concernsthree drainages on the southwestern flank of the volcano and one alluvial fan. A first analysis hasbeen conducted assessing geomorphologic features in the drainages testifying from erosional anddepositional processes during past lahars, in particular of those generated during the last eruptiveevent dating back to 1877 AD. Although the types of determined geomorphologic features are thesame, their spatial distribution varies among the three valleys as a function of an interplay of localmorphologic parameters. The individual environmental conditions determine also the flow volumeof such lahars, a critical parameter when to delineating hazard zones in the adjacent lowlands. Thesecond analysis has therefore be performed at large scale on the alluvial fan forming at the mouthof the southernmost of the three drainages. An integral study of the surface morphology and naturalexposures was enriched with subsurface stratigraphic information obtained through a ground penetratingradar survey. The sediment architecture of the fan provides valuable insights on the distributionof erosional features and deposits. Different fan parts appear to be active at different times andlahar deposit thicknesses are highly variable as a function of flow type and volume. This allows torelate floodplain dynamics to the initiation zone of lahars on the upper flanks of the volcano. At last,this research led to integrate a new bulking function acknowledging for erosional processes in thevalleys into the lahar-modeling software LAHARZ allowing to better delineate lahar hazard zones onthe fan

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Cousineau, Mélanie L. "Tracing Biogeochemical Processes Using Sulfur Stable Isotopes: Two Novel Applications." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/23714.

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Abstract Dissimilatory microbial sulfate reduction (MSR) The specific objectives of the study were to provide the first measurements of sulfur isotope fractionation associated with acidophilic sulfate reducing-microorganisms, and to examine whether pH influences sulfur fractionation during MSR. The fractionation associated with the strains investigated was comparable to that of neutrophilic strains with similar metabolisms (4-12‰), but varied with pH. Two fractionation regimes were identified: one regime is consistent with fractionation during exponential growth, while the other – not identified previously - is not linked to active sulfate reduction and may result from internal sulfate accumulation. This would represent the first measurement of sulfur fractionation during sulfate uptake, the first step of MSR. Geological processes at the Cretaceous-Paleogene (KPg) boundary The KPg boundary is associated with one of the largest biological extinctions in the history of our planet. Two major geologic events - the Chicxulub bolide impact with evaporite terrane and the eruption of the Deccan continental flood basalts - coincide with the KPg boundary and have been identified as possible triggers for the extinctions, but their relative timing remains unresolved. The objectives of this study were to identify the contribution of these processes to the sulfur burden in the sedimentary environment of two freshwater KPg sections, and to determine their relative timing. The results demonstrate that the peak of Deccan volcanism post-dates the Chicxulub impact and the associated abrupt KPg mass extinction, thus precluding a direct volcanic causal mechanism, but shedding light on the underlying causes for the delayed recovery of ecosystems in the early Paleogene.

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Cripps, Jennifer Ann. "Environmental impact of Deccan Trap flood basalt volcanism : assessment of regional floral responses to late Cretaceous-early Tertiary activity." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272896.

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Fitrianto, Achmad Room. "The Socio-Economic Impacts of the Porong Mud Volcano on the Shrimp Fisheries Sector in Sidoarjo District, East Java Province, Indonesia." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/80915.

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This thesis analyses the socioeconomic impact of the Sidoarjo mud volcano on shrimp fisheries’ production. It adapts the sustainable livelihoods framework in order to investigate how local livelihood assets are utilised to maintain and adapt livelihood strategies in response to river pollution in the context of a local and globalised aquaculture industry.

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Dondin, Frédéric. "Simulations numériques et impact tsunamogène d'une déstabilisation de flanc au volcan sous-marins Kick'em Jenny : petites Antilles." Antilles-Guyane, 2010. http://www.theses.fr/2011AGUY0388.

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Les déstabilisation de flancs sont un phénomène destructeur capable d'affecter un volcan quel que soit son contexte géodynamique. Dans cette thèse, le cas d'un épisode de déstabilisation de flanc est étudié pour le volcan sous-marin Kick'em Jenny. L'objectif primordial est de pouvoir appréhender le comportement dynamique de l'écoulement généré par la déstabilisation d'un flanc du proto-édifice. Pour ce faire, une étude du dépôt considéré comme étant issu de cet épisode de destruction est présentée afin d'évaluer le volume mobilisé. Cette déstabilisation de flanc est simulée à l'aide du modèle VolcFlow, basé sur une approche eulérienne de la résolution des équations de St-Venant moyennées sur l'épaisseur de l'écoulement. Deux modèles rhéologiques sont testés afin d'estimer lequel est plus à même de reproduire le comportement dynamique de l'écoulement et la mise en place du dépôt dans sa position finale. L'effet tsunamogène local (i. E. à la source) de cet épisode de déstabilisation de flanc est simulé l'aide de VolcFlow et de TOPICS (code de génération de caractéristiques de la perturbation de la surface libre à partir des spécificités de la déstabilisation). Enfin l'effet tsunamogène régional, lié à la propagation du tsunami dans le Bassin de Grenade est évalué à partir de simulations effectuées à l'aide de FUNWAVE (modèle propagation de tsunami) en considérant un modèle de propagation de type Boussinesq Flank collapses are destructive phenomena affecting volcanoes no matter their geodynamical context. In this thesis, we focus on the case of a flank collapse episode that occured at Kick'em Jenny submarine volcano. The main goal of this thesis is to assess the dynamical behaviour of the flow generated by the flank collapse episode at the proto-edifice. To do so, we first estimate volume involved in the collapse. The collapse event is simulated using VolcFlow, a model based on depth-averaged approximation of the St-Venant equations. Two rheological models are tested so that we can evaluate which one is most appropriate to reproduce the dynamical behaviour of the flow and the deposit features. Tsunamigenic effect at the source (local effect) is investigated by simulation tests using both VolcFlow and TOPICS (code providing tsunami source parameters from collapse characteristics). At last the regional tsunamigenic effect due to wave propagation towards the neighbouring islands is assessed using FUNWAVE, a Boussinesq-based model of wave propagation

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Dupart, Yoan. "Impact de la chimie des poussières minérales sur la photochimie atmosphérique." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10292/document.

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Les travaux de cette thèse reposent sur l’étude des processus hétérogènes à la surface desparticules minérales en présence d’irradiation UV-A. Nous savons que les poussièresminérales contiennent des oxydes métalliques pouvant absorber la radiation solaire et ainsiactiver une chimie très différente de celle observée à l’obscurité. Un réacteur à écoulementd’aérosols a été utilisé pour étudier les interactions des gaz (SO2, NO2 et O3) avec devéritables poussières minérales, évitant ainsi les artéfacts de mesure liés à la naturemacroscopique des films comme dans les études précédentes.La mise en suspension des poussières minérales a permis d’observer une formation inattenduede nouvelles particules ultrafines en présence de SO2. Le mécanisme proposé pour expliquerce phénomène de nucléation suggère une désorption de radicaux OH photoproduits à lasurface des minéraux vers la phase gazeuse. Ce mécanisme a pu être corroboré par descampagnes de mesure en atmosphère réelle. Nous avons étudié la chimie des échantillons de réelles cendres volcaniques issus de la dernière éruption du volcan Eyjafjallajökull en Islande (2010). Ceci nous a permis d’élaborerdes cinétiques de capture du SO2 sur des films macroscopiques de cendres aboutissant à descoefficients de capture de l’ordre de 10-7. Ces cinétiques couplées à des analyses chimiquesont permis de proposer un mécanisme réactionnel expliquant la formation de sulfate de fer àla surface des cendres. Finalement, nous avons étudié les interactions photochimiques de O3 et NO2 sur les poussièresminérales dans le réacteur à écoulement mettant en évidence un bon accord avec des étudesantérieures sur des surfaces macroscopiques The objective of this work is to study the heterogeneous processes of mineral dust surfacesunder UV-A radiation. It is know that mineral dust containing metal oxides which can absorbsolar radiation and therefore activate a different chemistry compared to that observed in thedark. In order to avoid measurement artifacts related to the nature of macroscopic films, anaerosol flow tube was developed during this work and applied to study the interactions ofSO2, NO2 and O3 with real mineral dust.An unexpected formation of new particles in the presence of SO2 was observed. In order toexplain this phenomenon, we suggest the desorption of OH radicals from the mineral dustsurface to the gas phase. This mechanism has also been supported by field campaigns.Using real samples of volcanic ash from the last eruption of Eyjafjallajökull in Iceland (2010)allowed us study capture of SO2 on macroscopic ashes films with uptake coefficient around10-7. Associated kinetic experiments combined with chemical analysis allowed us to propose areaction mechanism explaining the formation of iron sulfate on the surface of ashes.Finally, we investigated the photochemical interactions of O3 and NO2 with minerals dustaerosols in the flow tube reactor showing a good agreement with previous data obtained onmacroscopic surfaces

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Iwalewa, Tajudeen. "Coupling source term, mineral reactivity and flow in radionuclide transport." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/265633.

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The focus of this work is to investigate the dissolution of MW25, a non-radioactive simulant of UK high-level nuclear waste borosilicate glass, and to predict its performance in the near field of a geological repository. A single-pass flow-through (SPFT) experimental system was used to measure the forward dissolution rates of MW25. Experiments were conducted in two parts. Experiment Part 1 considers the dissolution of the waste glass in deionised water at 40 and 90 oC and circum-neutral pH. Experiment Part 2 considers the dissolution of the waste glass in simulant groundwaters, with similar compositions to groundwaters of Callovo-Oxfordian clay (lower-strength sedimentary rock (LSSR)) and Borrowdale Volcanic Group rocks (higher-strength rock (HSR)), at 40 oC and pH 7. The forward dissolution rate measured in deionised water was found to be approximately one order of magnitude higher at 90 oC than at 40 oC. A similar release was observed for Si, Mg and Al at 40 oC and 90 oC, whereas the B, Cs, Na, Li and Mo showed an order of magnitude increase when the temperature was increased from 40 to 90 oC for low q/S values. The activation energy (Ea) of the reactions shows that the dissolution process is a surface phenomenon. At 90 oC the net effect of the processes governing MW25 dissolution led to the preferential release of boron and alkali metals relative to the release of Si during the transient dissolution stage, accompanied by an increase in the concentration of silicic acid. This suggests that the solution activity of silicic acid at a higher temperature has a weak influence on the release of the mobile elements. The forward dissolution rate measured in LSSR simulant groundwater was found to be slightly higher than that measured in HSR simulant groundwater. The dissolution behaviour of MW25 in both groundwaters is consistent with its behaviour in deionised water at 40 oC, with the dissolution rates of elements increasing as flow rates were increased. However, forward dissolution rates measured in the simulant groundwaters were lower than the forward dissolution rates measured in deionised water under these experimental conditions. This is attributable to the interaction of the components of the simulant groundwaters with the glass, as revealed by post-reaction surface analyses, and a consequential lower alkalinity of the leachates collected in the experiments with simulant groundwater than in deionised water. Reactive chemical transport simulations of waste glass dissolution and radionuclide release in a hypothetical near field were conducted over a time span of a million years with GoldSim. The results showed that enclosing the waste glass in a steel canister covered by a copper canister and emplacing the waste package in a granite host rock is optimal for the long-term isolation of the radionuclides. The waste glass was found to play a significant role in the overall performance of the near field. This study features a new method for estimating the surface area of reacted glass powder more accurately than the geometric surface area estimate, which is the preferred standard method among researchers.

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Predybaylo, Evgeniya. "Volcanic Impacts on El Niño / Southern Oscillation." Diss., 2019. http://hdl.handle.net/10754/660122.

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El Niño / Southern Oscillation (ENSO) is arguably the most influential climate driver on Earth, so there is immense value for accurately forecasting it. The strong explosive volcanic eruptions provide a valuable opportunity to study the ENSO response to external forcing. Such volcanic eruptions can inject millions of tons of SO2 into the stratosphere, where they can convert into sulfate aerosols. For equatorial volcanoes, these aerosols can spread globally, scattering and absorbing incoming sunlight, and induce surface cooling worldwide. Despite this global cooling effect, the tropical Pacific Ocean surface often shows El Niño-like warming after strong volcanic eruptions. However, limited instrumental data cannot uncover the actual ENSO response to a robust external perturbation. Even modeling studies provide a limited understanding of the Volcano-and-ENSO interaction mechanism. This dissertation develops a firm understanding of the dynamical mechanisms of the ENSO response to tropical and high-latitude eruptions. It does so by developing a unified modeling framework that combines the roles of the seasonal cycle, stochastic forcing, eruption magnitude, and various tropical Pacific climate feedbacks. This study analyzes specifically designed climate model simulations spanning over 20000 years. This framework illuminates the nature of ENSO’s responses to past eruptions and explains why the El Niño-like response is more likely to occur during particular seasons and ENSO phases. It clarifies why prior studies obtained different and seemingly conflicting results. The ENSO response to strong volcanic eruptions is analyzed here in terms of stochastic and deterministic components. The partial contribution of these components determines the predictability and strength of the ENSO response to volcanic perturbation, and the ratio between them varies depending on the perturbation season and the ocean preconditioning. For boreal winter eruptions, stochastic dispersion largely obscures the deterministic response, being the largest for the strong El Niño preconditioning. Deterministic El Niño-like responses to summer eruptions are well seen on neutral ENSO and weak to moderate El Niño onsets and grow with the eruption magnitude. This improved understanding is expected to advance climate model simulations, predictions, and projections of ENSO, and its response to both tropical and high-latitude volcanic eruptions.

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"The Formation and Degradation of Planetary Surfaces: Impact Features and Explosive Volcanic Landforms on the Moon and Mars." Doctoral diss., 2018. http://hdl.handle.net/2286/R.I.48463.

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abstract: Impact cratering and volcanism are two fundamental processes that alter the surfaces of the terrestrial planets. Though well studied through laboratory experiments and terrestrial analogs, many questions remain regarding how these processes operate across the Solar System. Little is known about the formation of large impact basins (>300 km in diameter) and the degree to which they modify planetary surfaces. On the Moon, large impact basins dominate the terrain and are relatively well preserved. Because the lunar geologic timescale is largely derived from basin stratigraphic relations, it is crucial that we are able to identify and characterize materials emplaced as a result of the formation of the basins, such as light plains. Using high-resolution images under consistent illumination conditions and topography from the Lunar Reconnaissance Orbiter Camera (LROC), a new global map of light plains is presented at an unprecedented scale, revealing critical details of lunar stratigraphy and providing insight into the erosive power of large impacts. This work demonstrates that large basins significantly alter the lunar surface out to at least 4 radii from the rim, two times farther than previously thought. Further, the effect of pre-existing topography on the degradation of impact craters is unclear, despite their use in the age dating of surfaces. Crater measurements made over large regions of consistent coverage using LROC images and slopes derived from LROC topography show that pre-existing topography affects crater abundances and absolute model ages for craters up to at least 4 km in diameter. On Mars, small volcanic edifices can provide valuable insight into the evolution of the crust and interior, but a lack of superposed craters and heavy mantling by dust make them difficult to age date. On Earth, morphometry can be used to determine the ages of cinder cone volcanoes in the absence of dated samples. Comparisons of high-resolution topography from the Context Imager (CTX) and a two-dimensional nonlinear diffusion model show that the forms observed on Mars could have been created through Earth-like processes, and with future work, it may be possible to derive an age estimate for these features in the absence of superposed craters or samples. Dissertation/Thesis Doctoral Dissertation Geological Sciences 2018

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"Ponds, Flows, and Ejecta of Impact Cratering and Volcanism: A Remote Sensing Perspective of a Dynamic Moon." Doctoral diss., 2016. http://hdl.handle.net/2286/R.I.38376.

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abstract: Both volcanism and impact cratering produce ejecta and associated deposits incorporating a molten rock component. While the heat sources are different (exogenous vs. endogenous), the end results are landforms with similar morphologies including ponds and flows of impact melt and lava around the central crater. Ejecta from both impact and volcanic craters can also include a high percentage of melted rock. Using Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (LROC NAC) images, crucial details of these landforms are finally revealed, suggesting a much more dynamic Moon than is generally appreciated. Impact melt ponds and flows at craters as small as several hundred meters in diameter provide empirical evidence of abundant melting during the impact cratering process (much more than was previously thought), and this melt is mobile on the lunar surface for a significant time before solidifying. Enhanced melt deposit occurrences in the lunar highlands (compared to the mare) suggest that porosity, target composition, and pre-existing topography influence melt production and distribution. Comparatively deep impact craters formed in young melt deposits connote a relatively rapid evolution of materials on the lunar surface. On the other end of the spectrum, volcanic eruptions have produced the vast, plains-style mare basalts. However, little was previously known about the details of small-area eruptions and proximal volcanic deposits due to a lack of resolution. High-resolution images reveal key insights into small volcanic cones (0.5-3 km in diameter) that resemble terrestrial cinder cones. The cones comprise inter-layered materials, spatter deposits, and lava flow breaches. The widespread occurrence of the cones in most nearside mare suggests that basaltic eruptions occur from multiple sources in each basin and/or that rootless eruptions are relatively common. Morphologies of small-area volcanic deposits indicate diversity in eruption behavior of lunar basaltic eruptions driven by magmatic volatiles. Finally, models of polar volatile behavior during impact-heating suggest that chemical alteration of minerals in the presence of liquid water is one possible outcome that was previously not thought possible on the Moon. Dissertation/Thesis Doctoral Dissertation Geological Sciences 2016

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Alvarez, Barra Valentina. "Holocene vegetation dynamics and disturbance regimes in north Patagonia Argentina (40°S)." Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-141A-8.

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"Impact-Related Processes on Mercury and the Moon." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.20984.

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abstract: Impact craters are ubiquitous throughout the Solar System, formed by one of the principal processes responsible for surface modification of terrestrial planets and solid bodies (i.e., asteroids, icy moons). The impact cratering process is well studied, particularly on the Moon and Mercury, where the results remain uncomplicated by atmospheric effects, plate tectonics, or interactions with water and ices. Crater measurements, used to determine relative and absolute ages for geologic units by relating the cumulative crater frequency per unit area to radiometrically-determined ages from returned samples, are sensitive to the solar incidence angle of images used for counts. Earlier work is quantitatively improved by investigating this important effect and showing that absolute model ages are most accurately determined using images with incidence angles between 65° and 80°, and equilibrium crater diameter estimates are most accurate at ~80° incidence angle. A statistical method is developed using crater size-frequencies to distinguish lunar mare age units in the absence of spectral differences. Applied to the Moon, the resulting areal crater densities confidently identify expansive units with >300–500 my age differences, distinguish non-obvious secondaries, and determine that an area >1×104 km2 provides statistically robust crater measurements. This areal crater density method is also applied to the spectrally-homogeneous volcanic northern smooth plains (NSP) on Mercury. Although crater counts and observations of embayed craters indicate that the NSP experienced at least two resurfacing episodes, no observable age units are observed using areal crater density measurements, so smooth plains emplacement occurred over a relatively short timescale (<500 my). For the first time, the distribution of impact melt on Mercury and the Moon are compared at high resolution. Mercurian craters with diameters ≥30 km have a greater areal extent of interior melt deposits than similarly sized lunar craters, a result consistent with melt-generation model predictions. The effects of shaking on compositional sorting within a granular regolith are experimentally tested, demonstrating the possibility of mechanical segregation of particles in the lunar regolith. These results provide at least one explanation toward understanding the inconsistencies between lunar remote sensing datasets and are important for future spacecraft sample return missions. Dissertation/Thesis Ph.D. Geological Sciences 2013

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Holmes, TM. "The impact of volcanism on trace metal biogeochemistry in the Southern Ocean." Thesis, 2019. https://eprints.utas.edu.au/31725/1/Holmes_whole_thesis.pdf.

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Iron (Fe) is now recognised as a limiting, or co-limiting, micronutrient for biological production in the ocean. Areas of the ocean that are high in the macronutrients nitrogen (N) and phosphorous (P) but low in chlorophyll producing organisms are known as HNLC regions and cover approximately one third of the world’s oceans, the largest of which is the Southern Ocean (SO). When coupled with the inhibition of nitrogen fixation by microbes under low Fe conditions in low-latitude regions, this means that Fe regulates biological productivity in as much as half the world’s oceans. As such, Fe plays a key role in biogeochemical cycling and the drawdown of carbon from the atmosphere. Sources of Fe to the SO include resuspension of coastal and shallow sediments, glacial and iceberg melt, seasonal sea ice retreat, island wakes, vertical diffusive flux, interaction between bathymetry and currents, dust deposition and hydrothermal inputs. Hydrothermal inputs, in particular, have gained increasing recognition in recent years as a previously overlooked source of Fe to the deep ocean that may potentially affect surface productivity in some ocean basins. Furthermore, shallow hydrothermal vents and subaerial volcanic islands, while less common than deep mid-ocean ridge vents, may supply Fe directly to the surface mixed layer. This dissertation explores the impact of both hydrothermal and subaerial aspects of volcanism on Fe biogeochemistry in the SO. First, the impact of hydrothermalism on Fe cycling in the SO is explored through an extensive compilation of global hydrothermal studies and hydrothermal Fe measurements. This review highlights a dearth of hydrothermal studies conducted in the SO, with only 72 of the 631 vents discovered located south of 30° at the time of writing. A total of 31 of the 72 SO vents are located in the upper 2000 m of the water column, with 16 located in the upper 1000 m, increasing the probability of hydrothermal Fe reaching surface waters transported in upwelling SO meridional circulation. However, with only a small fraction of the ~20,000 km of tectonic plate boundaries located in the SO surveyed to date, many more observations at hydrothermal vent sites and further investigation of Fe transport mechanisms are required in order to constrain the impact of hydrothermalism on the SO and global ocean Fe cycles. Within the Indian sector of the SO lies an oasis of relatively Fe rich waters overlaying the Kerguelen Plateau. At the southern part of the central Kerguelen plateau is an active volcanic hotspot, hosting two subaerial volcanically active islands, Heard and McDonald (HIMI), the former of which is largely covered by glaciers. Waters in the region are subject to an intense mixing regime, caused by shallow bathymetry and the location of the plateau in the path of strong currents associated with the polar front. Fed by the Fe rich waters formed on the plateau, a phytoplankton bloom on the order of thousands of square kilometres forms in the lee of the plateau annually each summer. Few studies to date have focused on HIMI due to its extreme isolation. As such, the role of HIMI in the region’s biogeochemical cycling is relatively unknown. In order to examine the impact of these subaerial volcanoes on biogeochemical cycling in the area, dissolved iron (DFe) and macronutrient (NO$_3$$^-$, PO$_4$$^{3-}$ and Si) data from waters surrounding HIMI was collected on the RV Investigator during the Heard Earth-Ocean-Biosphere Interactions (HEOBI) voyage (GEOTRACES process study GIpr05) in January to February 2016. Results show that DFe availability drives macronutrient uptake on the plateau. In late summer the majority of the plateau to the north of HIMI contains a deficit of DFe relative to macronutrients with respect to phytoplankton requirements, although dissolution of particulate Fe is expected to fulfil at least some of the Fe demand. Comparison of Fe:N and Fe:P drawdown ratios with the Redfield ratio indicate that recycling of Fe decreases near HIMI, indicating that Fe limitation is alleviated close to the islands. Comparison with data from the only previous study in the area shows that DFe distribution varies between years due to the complex oceanographic conditions on the plateau, with greatest variability observed over the rough bathymetry and strongly tidally influenced region closest to HIMI. Together these data highlight the central role of Fe and the complexity of biogeochemical cycling in the HIMI region of the Kerguelen plateau. Finally, processes supplying DFe around HIMI are further constrained by examining the DFe redox speciation and hydrogen peroxide (H$_2$O$_2$) chemistry in the region, analysed during the HEOBI voyage. Dissolved iron(II) (DFe(II)) is the reduced, short lived, potentially more bioavailable oxidation state of Fe in the ocean. Concentrations of DFe(II) in the surface ocean are inversely correlated to the concentration of reactive oxygen species such as H$_2$O$_2$, which decrease DFe(II) half-life. Surface DFe(II) concentrations at the open ocean reference station were very low (<0.09 nmol L$^{-1}$), while stations near HIMI showed elevated concentrations over the entire water column (mean 0.24 nmol L$^{-1}$ and 0.36 nmol L$^{-1}$, respectively). At Heard Island, the greatest DFe(II) concentrations (max 0.57 nmol L$^{-1}$) were detected north of the island, and an inverse correlation of DFe(II) concentrations with salinity suggest the origin is from a marine-terminating glacier on the island. At McDonald Islands, the greatest DFe(II) concentrations (1.01 nmol L$^{-1}$) were detected east of the island which, based on water column profiles from five targeted stations and observed excess $^3$He concentrations, appears likely to originate from shallow diffuse hydrothermalism. DFe(II):DFe(total) ratios at the sites of high DFe(II) concentrations at Heard and McDonald Islands (25% and 37%, respectively) adds further evidence that strong, but different sources of reduced Fe exist at each of the islands. Furthermore, lack of correlation with H$_2$O$_2$ and irradiance data suggest that over the plateau near HIMI, DFe(II) concentrations are more strongly governed by strong DFe(II) sources rather than by H$_2$O$_2$ and irradiance. The findings presented in this thesis highlight the importance and sparse knowledge of the impact of hydrothermalism to Fe cycling in the SO, and significantly improve understanding of how the subaerial HIMI volcanoes influence biogeochemical cycling at a biological and volcanic hotspot in the SO.

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"Analysis of Spacecraft Data for the Study of Diverse Lunar Volcanism and Regolith Maturation Rates." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.20943.

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abstract: Lunar Reconnaissance Orbiter (LRO) and MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft missions provide new data for investigating the youngest impact craters on Mercury and the Moon, along with lunar volcanic end-members: ancient silicic and young basaltic volcanism. The LRO Wide Angle Camera (WAC) and Narrow Angle Camera (NAC) in-flight absolute radiometric calibration used ground-based Robotic Lunar Observatory and Hubble Space Telescope data as standards. In-flight radiometric calibration is a small aspect of the entire calibration process but an important improvement upon the pre-flight measurements. Calibrated reflectance data are essential for comparing images from LRO to missions like MESSENGER, thus enabling science through engineering. Relative regolith optical maturation rates on Mercury and the Moon are estimated by comparing young impact crater densities and impact ejecta reflectance, thus empirically testing previous models of faster rates for Mercury relative to the Moon. Regolith maturation due to micrometeorite impacts and solar wind sputtering modies UV-VIS-NIR surface spectra, therefore understanding maturation rates is critical for interpreting remote sensing data from airless bodies. Results determined the regolith optical maturation rate on Mercury is 2 to 4 times faster than on the Moon. The Gruithuisen Domes, three lunar silicic volcanoes, represent relatively rare lunar lithologies possibly similar to rock fragments found in the Apollo sample collection. Lunar nonmare silicic volcanism has implications for lunar magmatic evolution. I estimated a rhyolitic composition using morphologic comparisons of the Gruithuisen Domes, measured from NAC 2-meter-per-pixel digital topographic models (DTMs), with terrestrial silicic dome morphologies and laboratory models of viscoplastic dome growth. Small, morphologically sharp irregular mare patches (IMPs) provide evidence for recent lunar volcanism widely distributed across the nearside lunar maria, which has implications for long-lived nearside magmatism. I identified 75 IMPs (100-5000 meters in dimension) in NAC images and DTMs, and determined stratigraphic relationships between units common to all IMPs. Crater counts give model ages from 18-58 Ma, and morphologic comparisons with young lunar features provided an additional age constraint of <100 Ma. The IMPs formed as low-volume basaltic eruptions significantly later than previous evidence of lunar mare basalt volcanism's end (1-1.2 Ga). Dissertation/Thesis Ph.D. Geological Sciences 2013

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"The Ancient Rocky Surfaces of Mars: Analysis of Spacecraft Data and the Development of Laboratory Instrumentation." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.15789.

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abstract: Early spacecraft missions to Mars, including the Marnier and Viking orbiters and landers revealed a morphologically and compositionally diverse landscape that reshaped widely held views of Mars. More recent spacecraft including Mars Global Surveyor, Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, and the Mars Exploration Rovers have further refined, enhanced, and diversified our understanding of Mars. In this dissertation, I take a multiple-path approach to planetary and Mars science including data analysis and instrument development. First, I present several tools necessary to effectively use new, complex datasets by highlighting unique and innovative data processing techniques that allow for the regional to global scale comparison of multiple datasets. Second, I present three studies that characterize several processes on early Mars, where I identify a regional, compositionally distinct, in situ, stratigraphically significant layer in Ganges and Eos Chasmata that formed early in martian history. This layer represents a unique period in martian history where primitive mantle materials were emplaced over large sections of the martian surface. While I originally characterized this layer as an effusive lava flow, based on the newly identified regional or global extent of this layer, I find the only likely scenario for its emplacement is the ejecta deposit of the Borealis Basin forming impact event. I also re-examine high thermal inertia, flat-floored craters identified in Viking data and conclude they are typically more mafic than the surrounding plains and were likely infilled by primitive volcanic materials during, or shortly after the Late Heavy Bombardment. Furthermore, the only plausible source for these magmas is directly related to the impact process, where mantle decompression melting occurs as result of the removal of overlying material by the impactor. Finally, I developed a new laboratory microscopic emission and reflectance spectrometer designed to help improve the interpretation of current remote sensing or in situ data from planetary bodies. I present the design, implementation, calibration, system performance, and preliminary results of this instrument. This instrument is a strong candidate for the next generation in situ rover instruments designed to definitively assess sample mineralogy and petrology while preserving geologic context. Dissertation/Thesis Ph.D. Geological Sciences 2012

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Chao, Hung-Chun, and 趙鴻椿. "Chemical Compositions of the Mud Volcano Gases on land in Taiwan: Possible Impact on Global Methane Sources." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/74673840388649929890.

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碩士 國立成功大學 地球科學系碩博士班 91 Mud volcanoes are important pathway for methane emission from deeply buried sediments but were considered to be negligible in global budget consideration. The emitting gases from various mud volcanoes on land in Taiwan were collected and analyzed. The major components in southwestern mud volcanoes are methane (>80%), air (N2+O2+Ar, 1~10%) and carbon dioxide (1~5%). The highest methane concentration of 98% CH4 was detected at Siaoguenshui. It is interesting to note that the Juoshuitan at Chunglune, Chiayi shows much lower methane content, carbon dioxide (78%), methane (14%) and air (8%). Mud volcano gases collected from eastern Taiwan display significantly higher air (5~20%) with extremely low carbon dioxide (<0.2%). Applying a maturation index [C1 (methane) / C2 (ethane)+C3 (propane)], mud volcanoes gases in Chiayi and Yangnvhu fields are of thermogenic origin (R=59 - 138). The gasses collected from southwestern and eastern Taiwan are mixtures of thermogenic and biogenic (R=542 - 2438). High spatial time-series experiments were conducted at four mud volcano fields, Wusandin, Siaoguenshui, Guenshuipin, and Loushan. There are large variations in methane flux (up to 20% at Wusandin). The estimated methane flux generated from mud volcanoes on land in Taiwan ranges from 980 and 2000 tons/year. The possible methane release globally from mud volcanoes can reach a total amount 8.45 to 16.9 Tg per year, which may impact significantly the budget distributions of natural methane.

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Williams, Rebecca. "Modeling lahars using Titan2D for the southern drainage of Volcan Cotopaxi: Impact on the city of Latacunga." 2006. http://proquest.umi.com/pqdweb?did=1203555331&sid=7&Fmt=2&clientId=39334&RQT=309&VName=PQD.

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Thesis (M.S.)--State University of New York at Buffalo, 2006. Title from PDF title page (viewed on Mar. 16, 2007) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Sheridan, Michael F. Includes bibliographical references.

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Michelangeli, Diane Vera. "I. Impact of Volcanic Aerosols on Stratospheric Chemistry. II. O₂(¹Σg⁺) and O₂(¹Δg⁺) in the H + O₂ Reaction System. III. Barotropic Instability of Zonal Jets on Mars, Earth and Venus". Thesis, 1989. https://thesis.library.caltech.edu/2550/3/michelangeli-dv_1989.pdf.

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In order to fully understand an atmospheric system, we must answer questions in radiative transfer (Paper I), dynamics (Paper II), and chemistry (Paper I). The adequacy of the chemical models at reproducing the atmosphere depends on the fundamental knowledge of rate constants and absorption cross sections, which are determined in laboratory experiments (Paper III). All these issues are investigated in the three independent papers of this thesis. While seemingly unrelated, they all attempt to explain observations of terrestrial atmospheres. Paper I focuses on the chemical effects, in the Earth's stratosphere, of a volcanic eruption. Paper II reports experimental results important for the understanding of nightglow emissions on Earth. And finally, Paper III discusses barotropic instabilities as a possible explanation for thermal waves on Mars.

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Bellomo, S. "Environmental impact of magmatic fluorine emission in the Mt. Etna area." Thesis, 2005. http://hdl.handle.net/2122/349.

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Fluorine is the most reactive and the most electronegative of all elements, meaning that it has a powerful attraction for electrons and that it is able to attack all other elements, with the exception of oxygen and nitrogen, so it is not found in the free elemental state in nature. Fluorine is widely distributed throughout the earth’s crust as the fluoride ion. Fluorine is reported to be the 13th most abundant element in the earth’s crust (Smith and Hodge, 1979), with an average concentration of 0.032% by weight. Fluorides are released into the environment naturally through the weathering and dissolution of minerals, the emissions from volcanoes and from marine aerosols (WHO, 2002). Fluorides are also released into the environment via coal combustion and process waters and waste from various industrial processes, including steel manufacture, primary aluminium, copper and nickel production, phosphate ore processing, phosphate fertilizer production and use, petroleum refining, glass, brick and ceramic manufacturing, and glue and adhesive production (WHO, 2002). Based on available data, phosphate ore production and use as well as aluminium manufacture are the major industrial sources of fluoride release into the environment. According to Wellburn (1997), fluorine (in the form of HF) occupies - after O3, SO2 and nitrogencontaining air pollutants - the fourth place with regard to its detrimental effects on harvest, at least in the US. Relative to its weight fluorine even has the highest level of phytotoxicity of all air pollutants. Wellburn (1997) reports that F-related damages at sensitive plants can develop at concentration levels 10 to 10.000 times lower than other pollutants. There is no doubt that inorganic fluoride was one of the major air pollutants of the 20th century damaging crops, forests and natural vegetation, and causing fluorosis in factory workers, livestock and wild mammals. However there have been enormous improvements during the last 40 years in the containment and scrubbing of emissions, so that modern fluoride emitting industries generally have little or no environmental impact outside the factory fence at the present time (Weinstein and Davison, 2003). On the other hand, fluoride emissions from volcanoes and the natural occurrence of excessive amounts of fluoride in drinking water have affected the health of humans and livestock for centuries, if not millennia. For example some historical report tells that Pliny the Elder was dispatched by fluoride-containing fumes from a Vesuvian eruption, although other state that the cause of its death had actually no relation to volcanic activity. Whether the story is true or not,fluoride was certainly the agent responsible for the death of sheep after the volcanic eruption described in the Icelandic sagas, and fluoride emissions from volcanoes continue to affect the health of humans and livestock today (Georgsson and Petursson, 1972; Fridriksson, 1983; Araya et al.,1990; Cronin et al., 2002). Fluorine is emitted by volcanoes mostly as HF, but emissions from Vesuvius and Vulcano in Italy have been shown to contain also NH4F, SiF4, (NH4)2SiF6, NaSiF6, K2SiF6 and KBF4 (Weinstein and Davison, 2003). Volcanoes are also an important source of organo-fluorides, including some CFCs (Schwandner et al., 2004). Estimations of the global release of fluorine to the atmosphere by volcanic activity ranges from 50 to 8600 Gg/a (Cadle, 1980; Symonds et al., 1988; Halmer et al., 2002) with the lowest figures being probably an underestimate. Average HF emission rates from Mt. Etna can be estimated to about 75 Gg/a (Aiuppa et al., 2004a). This makes Mt. Etna the largest known point atmospheric source of fluorine (Francis et al., 1998), even stronger than todays estimated anthropogenic release over whole Europe (Preunkert et al., 2001). The environmental impact of anthropogenic fluorine emissions have long been studied considering all main type of activity, for example coal burning (Ando et al., 2001), aluminium smelters (Egli et al., 2004) or phosphate fertiliser production (Klumpp et al, 1996) and all types of receptors (air – Liu, 1995; glaciers - Preunkert et al., 2001; surface waters – Skjelkvale, 1994; vegetation – Weinstein, 1977; Weinstein and Davison, 2003; soils – Polomski et al., 1982; wildlife – Kierdorf and Kierdorf, 2000; etc.). Considerably fewer studies have been devoted to the consequences of volcanic fluorine emissions and most of them were focussed on the impact of fluorine released through explosive volcanic eruptions (Georgsson and Petursson, 1972; Oskarsson, 1980; Thorarinsson, 1979; Cronin et al., 2002). Recent researches have highlighted that passive degassing – quietly but persistently releasing volcanogenic pollutants - may also have profound impact on the ecosystems downwind, sometimes disrupting the social and economic activities of populations (Delmelle et. al., 2002; Delmelle, 2003). In this context, the impact of volcanogenic fluorine has been assessed on vegetation growing along the flanks of volcanoes (Guadeloupe – Garrec et al., 1977; Masaya – Garrec et al., 1984; Etna – Garrec et al., 1984; Notcutt and Davies, 1989; La Palma – Davies and Nottcut, 1989; Hawaii - Notcutt and Davies, 1993; Furnas - Notcutt and Davies, 1999) on rainwater chemistry (Hawaii - Harding & Miller, 1982; Vulcano Island – Capasso et al., 1993; Etna – Aiuppa et al., 2001; Stromboli Island – Bellomo et al., 2003) and on soils (Delmelle et al.,2003). The aim of the present PhD thesis is to provide original data on the geochemical cycling of fluorine of an active volcanic system like Mt. Etna. An assessment of the impact of volcanic fluorine on the local environment is also attempted by analysing different media (atmospheric air, rainwater, volcanic ashes, vegetation and soil). -UniversitÃ degli Studi di Palermo, Italy -Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo - Unione Europea, Fondo Sociale Europeo Published open

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Michelangeli, Diane V. "I. Impact of volcanic aerosols on stratospheric chemistry. II. O2(1sigma g+) and O2(1delta g) in the H + O2 reaction system. III. Barotropic instability of zonal jets on Mars, Earth and Venus." Thesis, 1989. https://thesis.library.caltech.edu/2550/1/Michelangeli_dv_1989.pdf.

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In order to fully understand an atmospheric system, we must answer questions in radiative transfer (Paper I), dynamics (Paper II), and chemistry (Paper I). The adequacy of the chemical models at reproducing the atmosphere depends on the fundamental knowledge of rate constants and absorption cross sections, which are determined in laboratory experiments (Paper III). All these issues are investigated in the three independent papers of this thesis. While seemingly unrelated, they all attempt to explain observations of terrestrial atmospheres. Paper I focusses on the chemical effects, in the Earth's stratosphere, of a volcanic eruption. Paper II reports experimental results important for the understanding of nightglow emissions on Earth. And finally, Paper III discusses barotropic instabilities as a possible explanation for thermal waves on Mars.

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48

Durowoju, Olatunde Samod. "Trace element concentrations in geothermal springs and their impact on soil and vegetation in Siloam and Tshipise." Diss., 2015. http://hdl.handle.net/11602/336.

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MENVSC Department of Hydrology and Water Resources ABSTRACT Siloam and Tshipise Springs are scalding geothermal springs geologically located within the Soutpansberg Group in the Limpopo Province of South Africa. These geothermal springs are associated with faults and impermeable dykes and are assumed to be of meteoric origin. The optimal use of a geothermal spring largely depends upon its physical and chemical properties as well as the geological controls at source and surrounding pathway to the surface. This study aimed at investigating trace element concentrations in these geothermal springs in order to quantify their impacts on neighbouring soil and vegetation. Impact on vegetation was assessed by incorporating seasonal variations of the trace element mobility from the geothermal springs to the vegetation (Mangifera indica at Siloam and Acacia robusta at Tshipise) via soil. The geothermal spring water, soil and vegetation samples at both sites were collected from May – July (winter) and September – November (summer), 2014. The soil samples were collected at 5 m intervals up to 20 m away from the geothermal spring in each of the sites. The bark and leaf parts of the vegetation were sampled. The control samples for water, soil and vegetation were obtained from Riverside residence at University of Venda, Thohoyandou, Limpopo Province, where there is non-geothermal source of water. The temperature, electrical conductivity (EC), pH and total dissolved solid (TDS) of the geothermal spring water and control samples were determined in situ and in the laboratory. The water samples were acidified for major cations and trace elements determination. There were also non-acidified water samples for major anion analyses. The soil and vegetation samples were digested using microwave and hot block methods, respectively. Concentrations of arsenic (As), antimony (Sb), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), mercury (Hg), lanthanum (La), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), tin (Sn), strontium (Sr), tellurium (Te), thallium (Tl), titanium (Ti), tungsten (W), vanadium (V), and zinc (Zn) were determined by inductively coupled plasma – mass spectrometry (ICP-MS) (Agilent 7700 series). Concentrations of calcium (Ca), magnesium (Mg), sodium (Na) and potassium (K) were analysed using inductively coupled plasma – optical emission spectrometry (ICP-OES) (X – Series 2) whereas the concentrations of chloride (Cl-), fluoride (F-), nitrate (NO3-), phosphate (PO42-), bicarbonate (HCO3-) and sulphate (SO42-) were determined by ion chromatography (IC) (Dionex Model DX 500). Results from this study revealed that the geothermal springs were rich in trace elements compared to that from non-geothermal source of water. The mineral elements present were vii mainly due to rock-water interaction in the deep aquifer at both sites. The geothermal spring water is not fit for drinking because it is particularly high in fluoride (F) having 6.66 and 5.97 mg/L at Siloam ; 6.72 and 7.28 mg/L at Tshipise for winter and summer, respectively. Also, high Nickel (Ni) with 462 µg/L and 868 µg/L: Lead (Pb) with 652 µg/L and 211 µg/L at Siloam and Tshipise respectively, for summer season. In addition, it is not suitable for irrigation owing to high sodium absorption ratio (SAR) values which were above the standard guidelines (˂1) by South African Bureau of Standards (SABS) and World Health Organization (WHO) at both sites. In summer season, there were higher trace elements concentrations than in the winter season. The higher concentration values could be attributed to rainfall, which aids in the dissociation of rock particles, resulting in higher concentrations of these elements. Siloam spring water was more mineralised than Tshipise spring water, hence its neighbouring soils and vegetation possess more trace elements concentrations than the latter. Owing to their high mineral elements content, the geothermal spring water flows across the soil, making it vulnerable to sorption of the trace elements. The trace elements present in the surrounding soil of the geothermal spring were as a result of geothermal water and soil pedogenesis. The geothermal water contaminates the surrounding soil with substantial quantity of trace elements, which decreases with the distance from the geothermal spring, making far distanced soil less-contaminated. High levels of Cr, Co, Ni, Cu, Zn and Pb at Siloam soil can be attributed to more minerals present in the spring, therefore making absorption by Mangifera indica inevitable. Soils at Tshipise are moderately concentrated owing to moderate trace elements concentrations from the geothermal spring water. Generally, seasonal variations were observed in the parameters analysed in the geothermal spring water, surrounding soil and vegetation to ascertain the most favourable season in terms of the trace elements concentrations. There were higher concentrations of trace elements in the geothermal spring, particularly during the summer season, compared to the winter season; this leads to more contamination of the surrounding soils and vegetation. This study showed that geothermal spring has potential to enrich the neighbouring soils and vegetation with trace elements, which could result in contamination. It can be concluded that geothermal spring, despite its benefits to humans, also contaminates the surrounding surface soils with toxic trace elements. Soils are a platform for vegetation. Therefore, if the soil is contaminated by toxic elements, there are high possibilities that these trace elements are absorbed by the neighbouring vegetation, which is likely to affect human beings adversely.

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Krutilová, Kateřina. "Vliv složení a mikrostruktury vulkanických hornin na jejich technologické vlastnosti." Doctoral thesis, 2015. http://www.nusl.cz/ntk/nusl-349325.

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Because of a very variable geological composition of the Czech Republic, there is a various scale of all genetic types of rocks that are used for the production of crushed stone. The most often used group of rocks are effusive magmatic rocks, which represent about 34 % of crushed stone marketed (Starý et al. 2010). These rocks are used for all kinds of construction purposes including roads. The experimental material of crushed stone used in this thesis was sampled from 40 active quarries in the Czech Republic. The studied volcanic rocks originated from Neoproterozoic and Paleozoic complexes of Barrandien, Carboniferous and Permian of Krkonose Piedmont Basin, Carboniferous and Permian of Intrasudetic basin, area of ordovician Železné Hory, from the main volcanic center of Bohemian Massif in the north-west Bohemia (České středohoří Mts. and Doupov Mts.), Neovolcanic area of Czech Cretaceous basin and area of Neovolcanic East and West Sudeten. Petrographic study was carried out in a form of standard petrographic analysis of thin sections and chemical analysis, which helped inclusion of rocks to a classified systems. The whole suite of volcanic rocks was separated to five petrographic-technologic subgroups defined as: (1) rhyolites / porphyres, (2) phonolites, (3) basalts s.l., (4) spilites and (5)...

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Dissertations / Theses on the topic 'Volcanic impacts'

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