Дисертації з теми "Environment and Earth Sciences"
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Black, Benjamin A. (Benjamin Alexander). "Volatiles as a link between planetary interiors and the environment." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84920.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 163-179).
Volatiles derived from planetary interiors influence magma evolution and environmental processes. Over appropriate timescales, Earth's mantle, crust, ocean, and atmosphere constitute coupled systems. The apparently synchronous Siberian Traps eruption and end-Permian mass extinction offer an ideal test case to study the interactions between magmatism and climate. In this thesis, I use experimental petrology, numerical modeling, geochemical measurements, and field observations to investigate the petrologic sources, eruptive transfer, and climatic effects of volatiles released during emplacement of the Siberian large igneous province. In an extreme variation on terrestrial volatile cycling, I also explore the erosional history of Titan as recorded in valley networks carved by rivers of liquid hydrocarbons.
by Benjamin A. Black.
Ph.D.
Johnson, Sarah Stewart. "Mars in the late Noachian : evolution of a habitable surface environment." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45605.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
This dissertation addresses whether simple life forms might have existed on Mars during the late Noachian epoch, and whether those life forms, or their traces, can be detected today. It begins by analyzing the ancient Martian climate in light of new evidence that sulfur chemistry played a prominent role in the planet's early evolution. It finds that sulfur-induced greenhouse warming could have periodically heated the planet enough to support liquid water, thereby creating warm, wet, clement conditions. Moreover, it finds that those warming pulses, while short-lived over geologic time, may have persisted for hundreds of years. If sulfur helped create environmental conditions capable of hosting life, however, it also created conditions that were adverse to sustaining it. In particular, dissipation of sulfur volatiles cooled the climate, and sulfur rainout contributed to the acidity of Martian surface waters. The dissertation therefore proceeds to analyze the potential for persistence and detection of life in terrestrial environments with Mars-like characteristics. It first investigates the potential for detecting ancient life by searching for lipid biomarkers in sulfur-rich acid salt lakes, concluding that a variety of biomarkers may be more resistant to decay than previously believed. It then analyzes soil samples from permafrost, discovering the oldest independently authenticated viable organisms ever found, and positing low-level metabolic activity and DNA repair as a survival mechanism in ancient cells. Finally, the dissertation uses deep sequencing to examine prokaryotic diversity in a terrestrial Mars-like river characterized by low pH and high concentrations of iron and sulfur, with results considered in light of the implications for life detection approaches incorporating new, in situ "PCR in a chip" technology. The dissertation concludes by proposing future work, including the ultimate goal of developing a life detection instrument for Mars.
by Sarah Stewart Johnson.
Ph.D.
Mloszewski, Aleksandra. "Environmental and microstructural controls of short-term shell degradation in temperate, macrotidal environments." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40807.
Повний текст джерелаL’état de préservation des coquilles d’organismes marins dépend directement des conditions environnementales dans lesquelles elles se dégradent. Cette étude a pour but de déterminer les conditions de dégradation progressive de coquillages (Mytilus edulis) et de cristaux abiotiques d’aragonite déployés à l’interface eau-sédiment ainsi qu’enfouis (à 10-20 cm) durant treize mois, dans les zones haute et moyenne d’un marais salant, une plage et une crique de la Baie de Fundy (NB, Canada). Les changements macroscopiques, microscopiques et de masse sont discutés relativement aux conditions environnementales. Nos résultats montrent que: 1) la dégradation et les processus agissent très tôt après la déposition, et produisent des changement d’état significatifs en deçà de 13 mois post-mortem. 2) Dans les environments ci-dessus, la mue des tablettes de nacre de la surface de la coquille est le processus le plus efficace, suivi par la bioérosion, et la macération. 3) La dissolution joue un rôle secondaire durant la dégradation précoce des coquillages.
Dunn-Sigouin, Etienne. "Evaluation of northern hemisphere blocking climatology in the global environment multiscale (GEM) model and in the present and future climate as simulated by the CMIP5 models." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110589.
Повний текст джерелаLes performances du modele Global Environment Multiscale (GEM), qui est le modele numerique operationel Canadien, a reproduire les variabilites atmospheriques de basse frequence sont evaluees en premier lieu dans le contexte de la climatologie de bloquage atmospherique dans l'hemisphere Nord. Afin de valider le modele, un algorithme de detection de bloquage qui est a la fois comprehensif et relativement simple est applique aux donnees atmospheriques. Les resultats montrent que la frequence maximum de bloquage au dessus de l'Atlantique Nord et l'Europe de l'Ouest est generalement sous-estimee et il y un delai dans la saison d'amplitude maximale puisqu'elle se produit au printemps au lieu de tard en hiver. De plus, la frequence de bloquage est generalement sur-estimee au dessus du Pacifique Nord. Il a ete trouve que les erreurs dans la frequence de bloquage sont grandement associees aux erreurs dans la circulation climatologique de l'atmosphere. En fait, les ondes stationnaires modelisees montrent un delai saisonnier dans le nombre d'onde zonal 1 et un deplacement vers l'Est des composantes du nombre d'onde zonal 2. Ayant confiance en la capacite de notre index pour identifier des bloquages atmospheriques, nous appliquons notre methodologie sur des analyses preliminaires de bloquage climatologique dans l'hemisphere Nord a partir d'un sous-ensemble de modeles climatologiques faisant partie du Coupled Model Inter-Comparison Project Phase 5 (CMIP5). Les integrations historiques revelent que la frequence maximale de bloquage sur l'Euro-Atlantique est generalement sous-estimee durant la saison froide et que la sur-estimation de la frequence maximale de bloguage sur le Pacifique se produit tout au long de l'annee dans certains modeles. En comparaison, les integrations de type RCP8.5 montrent un leger indice d'une reduction de la frequence de bloquage sur le Pacifique meme si aucune tendance significative en terme de duree de bloquage n'a ete trouvee.
Meredith, Laura Kelsey 1982. "Field measurement of the fate of atmospheric H₂ in a forest environment : from canopy to soil." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79283.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 245-254).
Atmospheric hydrogen (H₂ ), an indirect greenhouse gas, plays a notable role in the chemistry of the atmosphere and ozone layer. Current anthropogenic emissions of H₂ are substantial and may increase with its widespread use as a fuel. The H₂ budget is dominated by the microbe-mediated soil sink, and although its significance has long been recognized, our understanding is limited by the low temporal and spatial resolution of traditional field measurements. This thesis was designed to improve the process-based understanding of the H₂ soil sink with targeted field and lab measurements. In the field, ecosystem-scale flux measurements of atmospheric H₂ were made both above and below the forest canopy for over a year using a custom, automated instrument at the Harvard Forest. H₂ fluxes were derived using a flux-gradient technique from the H₂ concentration gradient and the turbulent eddy coefficient. A ten-fold improvement in precision was attained over traditional systems, which was critical for quantifying the whole ecosystem flux from small H2 concentration gradients above the turbulent forest canopy. Soil uptake of atmospheric H₂ was the dominant process in this forest ecosystem. Rates peaked in the summer and persisted at reduced levels in the winter season, even across a 70 cm snowpack. We present correlations of the H₂ flux with environmental variables (e.g., soil temperature and moisture). This work is the most comprehensive attempt to elucidate the processes controlling biosphere-atmosphere exchange of H₂ . Our results will help reduce uncertainty in the present-day H₂ budget and improve projections of the response of the H₂ soil sink to global change. In the lab, we isolated microbial strains of the genus Streptomyces from Harvard Forest and found that the genetic potential for atmospheric H₂ uptake predicted H₂ consumption activity. Furthermore, two soil Actinobacteria were found to utilize H₂ only during specific lifecycle stages. The lifecycle of soil microorganisms can be quite complex as an adaptation to variable environmental conditions. Our results indicate that H₂ may be an important energetic supplement to soil microorganisms under stress. These results add to the understanding of the connections between the environment, organismal life cycle, and soil H₂ uptake.
by Laura Kelsey Meredith.
Ph.D.
Chan, Gabriel Angelo Sherak. "Trade and the environment : the political economy of CO₂ emission leakage with analysis of the steel and oil sands industries." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/115466.
Повний текст джерелаThesis: S.B., Massachusetts Institute of Technology, Department of Political Science, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 113-116).
Introduction: In 2007, scientists and governmental officials from around the world contributed to the United Nations-authorized Intergovernmental Panel on Climate Change's (IPCC) Fourth Assessment Report. Through peer-reviewed scientific research and governmental review, the IPCC came to the conclusion that "warming of the climate system is unequivocal," and that "most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations." The IPCC Fourth Assessment states that humans have "more likely than not" contributed to the phenomena of more frequent "warm spells/heat waves," larger "area[s] affected by droughts," more "intense tropical cyclones.. .and heavy precipitation events," and "extreme high sea level[s]." Citing "high agreement" and "much evidence," the IPCC states that "with current climate change mitigation policies and related sustainable development practices, global GHG [greenhouse gas] emissions will continue to grow over the next few decades." (Intergovernmental Panel on Climate Change, 2007)
by Gabriel A. Chan.
S.B.
Rapopo, Mafusi. "Petrogenesis of the syntectonic Matok Pluton in the Limpopo Belt (South Africa) and its implications of the geodynamic environment." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17993.
Повний текст джерелаENGLISH ABSTRACT: The ~2.67 Ga Matok pluton comprises calc‐alkaline pyroxene (px)‐bearing and px‐free granitoids. The pluton was constructed by means of two episodes of intrusion each of which had co‐magmatic px‐bearing and px‐free granitoid groups. All the granitoid groups (px‐bearing and px‐free) are characterised by non‐porphyritic and porphyritic varieties. The phenocrysts in both episodes of intrusion are plagioclase ± alkali feldspar and are aligned parallel to the trend of the Limpopo Belt, attesting to a syntectonic emplacement. The time gap between the first and second intrusion is insignificant and magma was most likely stored in the chamber after the first intrusion. Petrography and geochemical signature of both px‐bearing and px‐free granitoid samples have been studied and a petrogenetic model which accounts for the coeval px‐bearing and px‐free granitoids is proposed. The relevance of the syntectonic emplacement of the Matok pluton ie n the Limpopo Belt is also addrssed. Px‐bearing granitoids always have clinopyroxene but orthopyroxene is not always present. Magnetite and ilmenite are present in both px‐bearing and px‐free granitoids but are more abundant in the px‐bearing granitoids and subordinate in the px‐free granitoids. Plagioclase in both px‐bearing and px‐free granitoids is of oligoclase (An12‐30) composition but is relatively more calcic and increases in modal abundance in the px‐bearing granitoids. Alkali feldspar is more dominant in the px‐free granitoids. Hornblende is present in all the px‐bearing granitoids and the px‐free granitoids with ≤71 wt.% SiO2 but is absent in the px‐free granites with >71 wt.% SiO2. Both magmatic epidote and titanite occur exclusively in the px‐free granitoids with ≤71 wt.% SiO2 and are absent in all the px‐bearing granitoids as well as the px‐free gra nites with >71 wt.% SiO2. Px‐bearing granitoids are mainly of dioritic and granodioritic and have subordinate granitic composition while px‐free granitoids are mainly of granitic and granodioritic and have subordinate dioritic composition. All the rocks define well correlated variation of SiO2 with the rest of the major elements. However, there is always a hiatus between the granites with >71 wt.% SiO2 and all other rocks. Px‐bearing and px‐free granitoids at the same SiO2 concentrations tend to have approximately equal concentrations of MgO, CaO and TiO2, whereas K2O concentration is distinctively higher for the px‐free granitoids. The distribution of the high field strength elements (HFSE; Nb, Ta, Zr and Hf) and rare earth elements (REE) is similar in both px‐bearing and px‐free granitoids. On contrary, Th, U, Cs and Rb are characteristically higher in the px‐free granitoids. All granitoids are characterised by negative anomalies of the HFSE (Nb, Ta and Ti) and the LILE (Th, U and Sr) on primitive mantle normalised diagrams. On the one hand, concentrations of compatible elements (Cr, Ni and Mg) in the Matok pluton granitoids are rather low for a mantle source. On the other hand, all the granitoids have superchondtritic Nb/Ta ratios that overlap with those of the Ventersdorp continental flood basalts which extruded in the Kaapvaal Craton at ~2.7 Ga. The continental crust typically has subchondritic Nb/Ta ratio, and superchondtritic Nb/Ta ratios are widely accepted to resemble a mantle source. The implication is that the Matok pluton granitoids had inherited the superchondtritic Nb/Ta ratio from their source; juvenile underplated mafic magmas that had ponded owing to the impact of the Ventersdorp mantle plume. The large volumes of ponded magma s probably induced the high grade metamorphism in the Limpopo Belt. All the granitoids of the Matok pluton are probably products of one partial melting event. One possible way to account for the co‐existence of px‐bearing and px‐free granitoids in the Matok pluton is by means of, at least, two magma chambers; one which was filled with anhydrous magma and the other which was filled with hydrous magma. An alternative model would be that in which there was only one chamber. In the one chamber scenario, the magma was hydrodynamically sorted into zones that differed mostly in fH2O and concentrations of highly fluid‐mobile elements but conserved the uniformity in fluid immobile elements. Regardless of the number of chambers, magma batches intruded in the form of feeder dikes which minimally interacted, thus avoiding the hydration of pyroxene in the px‐bearing granitoids.
SELELEKELA: Plutone ya Matok e fumanehang profinsing ya Limpopo sebakeng seo ho digeologist se tsebahalang ka hore ke Lebanta la Limpopo e ile ya aheya dilemong tse 2.67 biliyone tse fetileng. Plutone ena eile ya aheya ka mekgahlelo e mmeli, mme mokgahlelo ka mong o ne o bopilwe ka majwe a nang le pyroxene le a senang yona. Majwe kaofela ke a mofuta wa calc‐alkaline. Phapang e kgolo dipakeng tsa mefuta ena e mmedi ya majwe ke boteng ba pyroxene le boteng ba epidote le titanite majweng a nang le pyroxene le a senang pyroxene ka ho latellana. Ha e le diminerale tse ding kaofela tsona ha likgethe mofuta wa lejwe; liteng mefuteng ya majwe ka bobedi. Kgonahalo ya hore plutone ya Matok e ahwe ka mefuta ena e mmedi (px‐bearing and px‐free) e tlile ka mekgoa e mmedi kapa o mong wa mekgwa ena yo ka bobedi e ka etsahalang. (1)Tlaase semelong sa lesheleshele moralla (magma) hone ho ena le didiba tse pedi, seseng se tshetse lesheleshele le chesang haholo ebile le le metsi a fokolang (anhydrous magma) ha se seng se ne se tshetse lesheleshele le metsi a mangata (hydrous magma). Ho tloheng moo didibeng tse pedi ho tla moo plutone ea Matok eleng teng kajeno masheleshele ana a ne a tla ka mokgwa wa di‐dike tseo kaofela phello ya tsona e neng e le sebakeng se le seng‐plutone ya Matok. (2) Mokgwa wa bobedi ke haeba ho ne ho ena le sediba se le seng sa lesheleshele moralla, mme ka sedibeng ka moo ho ne ho ena le maqulwana (zones) a neng a fapane ka bongata ba metsi. Ho tloha sedibeng moo masheleshele ana a ne a tloha ka bona boqulwana boo entse ele ka mokhwa wa di‐dike, mme kaofela phello ya di‐dike ene ele plutone ya Matok. Kaofela majwe a plutone ya Matok a na le feldspar eo boholo ba nako e patlameng ho ya nqa bophirimela‐bochabela (W‐E), e leng nqa eo Lebanta la Limpopo le phatlaletseng ka teng. Hona ho tiisa hore plutone ya Matok e aheile nakong yo Lebanta la Limpopo le neng le ntse le aheya le lona. Ke dilemong tse kabang 2.7 biliyone tse fetileng ha dikarolong tse ding tsa Cratone ya Kaapvaal ho ne ho aheya majwe a moralla a Ventersdorp. Majwe ana ke a hlahang tlaase botebong ba lefatshe (mantle), mme a susumeditswe ke plumo. Karolo boholo ya lesheleshele moralla hae ya ka ya nyoloha ho fihla hodimo lefatsheng. Empa mofuthu o mongata ho nyoloha leshelesheleng moo ke ona oileng wa 'pheha' majwe ho phatlalla le Lebanta la Limpopo. Ho nyoloha hona ha plumo ho etsahetse ka nako e lengwe le ho tsukutleha ho hoholo ho potapota le Cratone ya Kalahari, mme bobedi diketsahalo tsena diile tsa tswala Lebanta la Limpopo. Hobane plutone ya Matok e aheile hanghang ka mora hore lesheleshele la moralla le dule tlaase ho lekgapetla la lefatshe (crust), dielemente tse ratang haholo diminerale tsa ditemperetjha tse hodimo diile tsa feela jwalo di nkile lefa hotswa lesheleshele moralleng la Ventersdorp.
Wilkinson, John L. "Occurrence, bioaccumulation, fate and transport of pharmaceuticals, plasticisers, illicit drugs and perfluorinated compounds in the aquatic environment." Thesis, Kingston University, 2017. http://eprints.kingston.ac.uk/39283/.
Повний текст джерелаAdelman, Jessica. "Mineral interactions in a gold mining environment: change in oxidation rate of stibnite as affected by the addition of varying amounts of pyrite in an oxygenated flow through system." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92390.
Повний текст джерелаOn croit qu'un des mécanismes importants de dissolution de la stibnite (Sb₂S₃) dans les résidus miniers est par contact avec un minéral ayant un plus fort potentiel électrique, tel que la pyrite (FeS₂). L'objectif de la recherche était de déterminer l'impact du ratio stibnite vs. pyrite et l'effet du pH sur le taux de dissolution de la stibnite. Quatre essais de lessivage en colonnes ont été réalisés. Les deux premiers essais de lessivage avec de l'eau déionisée ont montré que le traitement contenant la plus forte proportion de pyrite (95% pyrite) a résulté en la plus grand quantité cumulative de Sb dissous (Exp #2-16730 mg Sb/kg stibnite). L'analyse spectroscopique par absorption des rayons-X (XANES) de la phase solide a révélé que la proportion de Sb total sous forme Sb(V)-O était plus importante dans le traitement 95% pyrite comparé à tous les autres traitements mixtes et au traitement contrôle de 100% stibnite. Ces observations indiquent que des interactions galvaniques ont eu lieu entre la stibnite et la pyrite. En utilisant une solution tamponnée à pH 7.5, il fut possible de déterminer l'effet d'un pH légèrement alcalin sur ces interactions entre la stibnite et la pyrite. Dans ces conditions, la quantité maximale de Sb dissous a été atteinte dans le traitement 95% pyrite (Exp #3-18090 mg Sb/kg stibnite), ce qui est comparable au traitement 95% pyrite dans l'expérience #2 de lessivage à l'eau. Cependant, l'analyse XANES a révélé une proportion moindre du Sb total sous forme d'oxide dans l'essai de lessivage à pH 7.5, possiblement en raison de la formation d'un complexe soluble entre Sb et HCO₃-. L'expérience #4 a testé l'impact de l'arsenopyrite sur la dissolution de la stibnite lors d'un lessivage à l'eau. Dans ce cas, le traitement 95% arsenopyrite (Exp #4-10311 mg Sb/kg stibnite) a libéré moins de Sb en solution comparé au traitement 95% pyrite de l'expérience #2, et ce résultat s'explique par la plus p
Williams, Jeni Kimberly. "Inquiry learning in the earth science classroom." CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2641.
Повний текст джерелаFenwick, Emily L. "The impact of an integrative 3-d virtual learning environment in diverse ninth grade earth and space science classes." Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/4231.
Повний текст джерелаDepartment of Geology
Iris M. Totten
Problem-based learning in the sciences has been demonstrated to be a successful educational approach to engage students and increase content knowledge. However, the power of collaborative learning to engage students, increase content knowledge and develop problem-solving skills in the sciences has not yet been fully researched. Collaborative learning has an enormous potential not only to foster student learning, but also to increase interest in the sciences and promote cutting-edge education strategies worldwide. Collaborative learning tactics in this study take place within the virtual learning environment entitled “GeoWorlds.” GeoWorlds is an online educational gaming program within the Second Life 3-D Teen Grid. The curriculum was developed as a collaborative, investigative and engaging program to promote learning of Earth science content. The program allows students to be submersed-in and explore different geologic time periods; enabling them to observe species and geological structures while interacting with one another to complete tasks. This study investigates the educational impact, emotional response and overall feedback of the GeoWorlds virtual learning environment on Midwest ninth graders.
Kalyva, Maria. "Fate of pharmaceuticals in the environment - A review-." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-132995.
Повний текст джерелаEbo, Obiorah Odili. "Evaluation of inquiry-based Learning in high school earth science and biology classrooms: learning environment and attitudes." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1299.
Повний текст джерелаJames, Michael R. "Electric charge within volcanic plumes on Earth and Io." Thesis, Lancaster University, 1999. http://eprints.lancs.ac.uk/35043/.
Повний текст джерелаSáenz, James Peter. "Exploring the distribution and physiological roles of bacterial membrane lipids in the marine environment." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59757.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references.
Lipids have a legacy in the geologic record extending back to the Archaean. Since the phylogenetic diversity of life is reflected in the structural diversity of biomolecules, lipid biomarkers that are shown to be diagnostic of certain organisms that carry out specific biochemical processes or that are demonstrated to have unique physiological roles can be used to trace the biogeochemical influence of bacteria in modern and ancient environments. In this thesis I explore the application of two classes of bacterial membrane lipids as biomarkers for marine biogeochemical processes in marine environments: ladderanes and hopanoids. Through the detection of ladderane lipids - biomarkers for anaerobic ammonium oxidizing (anammox) bacteria - I demonstrate the presence and distribution of anammox bacteria in a subterranean estuary. Through a survey of hopanoids in marine environments and cultured marine cyanobacteria I show that hopanoids are ubiquitous in the oceans and that their presence in ancient marine sediments could provide information about biogeochemical processes in past environments. Based on novel results demonstrating that hopanoids are resistant to extraction by non-ionic detergent, I propose that they may play a role in lipid ordering and the formation of putative lipid rafts in hopanoid-producing bacteria.
by James Peter Sáenz.
Ph.D.
Rodriguez, Tablante Johiris Isabel. "Extracting 3D Information from 2D Crooked Line Seismic Data on Hardrock Environments." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6510.
Повний текст джерелаSeismic methods have been used in sedimentary environment for almost 80 years. During that time, exploration geophysicists have developed a number of techniques to handle specific aspects of working in sedimentary areas. This is not the case for studies in the hardrock environment, where significantly less time and money have been invested on seismic investigations. Therefore, there is still a need to develop the right techniques appropriate for working in hardrock environments. The research presented here, covers aspects of acquisition, processing and interpretation in hardrock environments. A cost-effective alternative for two-dimensional data acquisition is presented. Acquisition parameters are also discussed and recommendations for future work are given. The main effort of this thesis, however, was to find appropriate processing methods to address some of the different problems present in datasets acquired in the hardrock environment. Comparison of two computer programs for first arrival seismic tomography was performed in order to find the most suitable one for processing crooked line geometries. Three-dimensional pre-stack depth migration was also tested to find a detailed near-surface image. A processing method geared to enhance the signal-to-noise ratio was applied to the dataset with the lowest signal amplitudes to improve the quality of the stack. Finally, cross-dip analysis and corrections were performed on two of the three datasets included in this thesis. Cross-dip analysis was also applied as an interpretation tool to provide the information needed for estimation of the true dip of some of the reflectors related to geological structures. The results presented in this thesis indicate that cross-dip analysis and corrections are one of the most powerful tools for processing and interpretation in the presence of complex geology. Therefore, it is recommended to include this method as a standard step in the processing and interpretation sequence of data acquired in hardrock environments.
Chaisan, Kittisak. "Modelling the environmental transfers of radioactivity following the Fukushima accident." Thesis, University of Portsmouth, 2015. https://researchportal.port.ac.uk/portal/en/theses/modelling-the-environmental-transfers-of-radioactivity-following-the-fukushima-accident(60b31ec7-b843-4878-b374-931c5234b90c).html.
Повний текст джерелаGu, Ailiang. "Stable Isotope Geochemistry of Sulfate in Groundwater of Southern Arizona: Implications for Groundwater Flow, Sulfate sources, and Environmental Significance." Diss., The University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2005_023_sip1_w.pdf&type=application/pdf.
Повний текст джерелаBohlin, Hanna. "The influence by point sources on carbon, nitrogen and metals in two sedimentary environments." Doctoral thesis, Stockholm : Dept. of geology and geochemistry, Stockholm university, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-753.
Повний текст джерелаFilion, Anna-Belle. "Severe weather intensity index using the 1-km global environmental multiscale limited area model output." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119464.
Повний текст джерелаLe temps violent (TV) estival peut avoir un impact important sur la vie des gens et leurs biens. En ce moment, aucun outil n'est assez performant pour aider les prévisionnistes à prévoir le TV. Cette thèse a pour but de créer un outil automatisé pour aider les prévisionnistes dans leurs prévisions de TV d'été. Un indice d'intensité de TV à été créé à partir des données du modèle global environnemental à multiéchelles à aire limitée (GEM-LAM) avec une résolution horizontale de 1 km. Le GEM-LAM 1-km à été roulé pour tous les jours d'été 2008 et 2009 sur les régions de l'Alberta, le sud de l'Ontario et le sud du Québec. Les données de l'été 2009 ont été utilisées pour créer des algorithmes qui utilisent les sorties du modèle pour détecter les structures particulières aux orages violents, évaluer les quantités de plusieurs éléments nécessaires à la formation d'orages violents, et estimer l'intensité et le type de TV attendu. Les champs post-traités ont été subjectivement analysé avec les observations de TV et les images radar pour l'été 2009 permettant de bâtir un arbre de décision pour l'indice d'intensité de TV pour chaque région. Une méthode par objet a été utilisée pour faire une vérification des prévisions de l'indice d'intensité de TV avec les observations de TV pour l'été 2008. Les résultats montrent que la prévision de l'indice d'intensité de TV est très juste pour l'Ontario, est assez juste pour le Québec, mais l'ai beaucoup moins pour l'Alberta. Le faible nombre d'observations de TV et le temps d'ajustement du modèle affectent les résultats. Finalement, la précision de l'indice d'intensité de TV et celle de la prévision de TV émit par un prévisionniste ont été comparées de façon à vérifier si l'indice peut aider le prévisionniste à améliorer sa prévision. Les résultats démontrent que l'indice d'intensité de TV pourrait améliorer la prévision d'un évènement, mais pas son positionnement.
Cooke, Melanie. "The synoptic- and planetary-scale environments associated with significant 1000-hPa geostrophic wind events along the Beaufort Sea coast." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86997.
Повний текст джерелаL'étude du climat régional et du météorologie du Mer Beaufort est motivée par son variabilité interannuelle important et par la réchauffement qui y est observée. En essayant de comprendre les évenements à vents forts, qui peuvent forcer les dynamiques du glace marine et les ondes tempêtes, leurs environnements caractéristiques aux échelles synoptiques et planétaires sont définies et analysées en utilisant la donnée globale réanalysée. Une dépendance sur une dépression Aleutienne augmentée ou diminuée est trouvée. Ca produit un évenement à vents géostrophiques forts à 1000-hPa soit du soud-est soit du nord-ouest. La modèle caractéristique du mi-troposphère pour ces deux types d'évenements distincts démontrent des similarités aux modèles Pacifique/Nord-Américain positive et negative, mais leurs corrélations ont besoin d'être évaluées.
Hadley, Kershaw Eleanor. "Co-producing Future Earth : ambiguity and experimentation in the governance of global environmental change research." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49869/.
Повний текст джерелаHenry, Christina. "Flash Flooding in Eastern Kentucky: An Analysis of the 3-4 August 2001 Event." TopSCHOLAR®, 2006. http://digitalcommons.wku.edu/theses/275.
Повний текст джерелаOlstrup, Henrik. "The Arctic Ice Melting Caused by Black Carbon from an Environmental Risk Analysis Perspective." Thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-15955.
Повний текст джерелаStrollo, Angelo. "Development of techniques for earthquake microzonation studies in different urban environment." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2011/5380/.
Повний текст джерелаAufgrund des enormen Wachstums neuer Megastädte und deren Vordringen in gefährdete Gebiete auf der einen Seite sowie der mangelnden Erdbebenvorsorge in vielen Entwicklungsländern auf der anderen Seite sind verbesserte Verfahren für die Beurteilung der Gefährdung sowie eine rasche Umsetzung bei der Raumplanung erforderlich. Im Rahmen der seismischen Gefährdungsabschätzung spielt insbesondere die Beurteilung lokaler Standorteffekte und deren Einfluss auf die durch ein Erdbeben verursachte räumliche Verteilung der Bodenerschütterung eine wichtige Rolle. Es ist daher unabdingbar, mittels seismischer Mikrozonierungsstudien diejenigen Bereiche innerhalb dicht besiedelter Gebiete zu ermitteln, in denen ein ähnliches Verhalten im Falle seismischer Anregung erwartet wird, um daraus eine zuverlässige Basis bei der Risikoabschätzung großer städtischer Gebiete zu erhalten. Aufgrund des schnellen Wachstums vieler Großstädte in Entwicklungsländern ist eine seismische Mikrozonierung zwingend erforderlich, stellt aber auch eine große Herausforderung dar; insbesondere müssen Verfahren verfügbar sein, mit deren Hilfe rasch eine Abschätzung der Standorteffekte durchgeführt werden kann. In der vorliegenden Arbeit entwickle ich daher Verfahren für die Untersuchung in Großstädten, die darauf abzielen, nicht-invasiv, kostengünstig und schnell durchführbar zu sein. Damit lassen sich innerhalb eines relativ kurzen Zeitraums große Gebiete untersuchen, falls der räumlichen Abstand zwischen den Messpunkten klein genug ist, um eine zuverlässige Mikrozonierung zu gewährleisten. Obwohl es eine gegenläufige Tendenz zwischen der Vollständigkeit aller Informationen und der Größe des untersuchten Gebiets gibt, versuche ich, diese Einschränkung durch Verknüpfung zweier Informationsebenen zu umgehen: In der ersten Ebene werden die Standorteffekte für einige Kalibrierungspunkte durch die Analyse von Erdbeben oder mittels anderer geophysikalischer Datensätze (z.B. Scherwellengeschwindigkeitsprofile) bestmöglich abgeschätzt, in der zweiten Ebene werden die Standorteffekte durch Einzelstationsmessungen des seismischen Rauschens für ein größeres Gebiet bestimmt. Die Mikrozonierung erfolgt hierbei mittels spezifischer, fallabhängiger Parameter unter Berücksichtigung eines geeigneten Anknüpfungspunktes zwischen den beiden Informationensebenen. Um diesen Ansatz der Mikrozonierung, der in dieser Arbeit verfolgt wurde, zu präzisieren, wurden in Potenza (Italien), wo eine beträchtliche Menge an Daten verfügbar war, verschiedene Verfahren untersucht. Insbesondere kann das Spektralverhältnis zwischen den horizontalen und vertikalen Seismometerkomponenten, welche für das seismische Rauschen an mehreren Orten aufgenommen wurde, als eine erste Näherung für die relative Verstärkung der Bodenbewegung verwendet werden, um darauf aufbauend die beiden Informationsebenen zu verknüpfen und eine Mikrozonierung hinsichtlich des Verhältnisses der spektralen Intensität durchzuführen. Anschließend führte ich diesen Zwei-Ebenen-Ansatz auch für Istanbul (Türkei) und Bischkek (Kirgisistan) durch. Für die Mikrozonierung dieser beiden Städte habe ich denselben Hybridansatz, der Daten von Erdbeben und von seismischem Rauschen verbindet, verwendet. Für beide Städte wurde nach Gegenüberstellung der Resonanzfrequenz des Untergrunds, die zum einen mit Hilfe des seismischen Rauschens, zum anderen durch Analyse von Erdbebendaten bestimmt worden ist (erste Ebene), eine Karte der Resonanzfrequenz unter Verwendung weiterer Messungen des seismischen Rauschens innerhalb des Stadtgebiets erstellt (zweite Ebene). Durch die Anwendung dieses neuen Ansatzes sind vor kurzem zum ersten Mal auch Karten für die Resonanzfrequenz des Untergrunds für Istanbul und Bischkek veröffentlicht worden. Parallel dazu wurde für das Testgebiet in Potenza eine auf dem spektralen Intensitätsverhältnis (SIR) basierende Mikrozonierungskarte in ein Risikoszenario mittels der Regression zwischen SIR und makroseismischer Intensität (EMS) integriert. Diese Szenariostudie bestätigt die Bedeutung von Standorteffekten innerhalb der Risikokette; insbesondere führt deren Einbeziehung in das Szenario zu einem Anstieg von etwa 50% bei der Zahl der Gebäude, für die ein teilweiser oder gar vollständiger Zusammenbruch erwartet werden kann. Abschließend wurde der im Rahmen dieser Arbeit entwickelte und angewandte Ansatz auf seine Zuverlässigkeit geprüft. Ein theoretisches Modell, das zur Beschreibung des Eigenrauschens verschiedener Instrumente, die in der Regel in Mikrozonierungsstudien (z. B. in Potenza, Istanbul und Bischkek) zum Einsatz kommen, wurde untersucht, und die Ergebnisse wurden mit Daten verglichen, die vorher bereits in Köln (Deutschland) und Gubbio (Italien) aufgenommen worden waren. Die Ergebnisse zeigen, dass abhängig von den geologischen und umgebenden Bedingungen das Eigenrauschen der Geräte die Ergebnisse bei der Analyse des seismischen Rauschens stark verzerren kann. Deshalb liefere ich in dieser Arbeit auch einige Leitlinien für die Durchführung von Messungen des seismischen Rauschens.
Ravindran, Nimmy. "Hide-Metadata Based Data Integration Environment for Hydrological Datasets." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/36157.
Повний текст джерелаMaster of Science
Bassein, Emma (Emma R. ). "A digital path to environmental education." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/114116.
Повний текст джерелаCataloged from PDF version of thesis. Pages 25 and 37-39 missing from original thesis.
Includes bibliographical references (page 28).
Digital technology has become completely engrained in the process of scientific research. Grade schools are beginning to incorporate computers and other digital devices into the learning process as tools for learning other subjects, including science. Educators have experimented with a variety of programs that incorporate computers, such as digital tutors, simulations of natural systems, and interactive simulations. This study aimed to demonstrate that handheld computers are a useful resource in problem-based learning environments. A "mini-curriculum", focused on making handheld computer-aided measurements of the key environmental parameters in marine estuaries, was designed and taught to eleven students from the Palmetto Ridge High School in Naples, Florida over a two week period. Students' reactions to both the curriculum and the computers were overwhelmingly positive. This proof-of-concept trial indicates that handheld computers have the potential to be a very useful tool in problem-based learning.
by Emma Bassein.
S.B.
Gydemo, Östbom Viktor. "Lake water chemistry and the changing arctic environment : Topographic or climatic control?" Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-155903.
Повний текст джерелаDanielson, Richard E. "Environmental influences on cold-season cyclones over the North Pacific Ocean." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19723.
Повний текст джерелаJensen, Mai-Britt Mose. "Geophysical tools for prognosis of deformation in hardrock environments." Doctoral thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25779.
Повний текст джерелаGodkänd; 2011; 20111021 (maimos); DISPUTATION Ämnesområde: Tillämpad geofysik/Applied Geophysics Opponent: PhD Satu Mertanen, Geological Survey of Finland, Åbo Ordförande: Professor Sten-Åke Elming, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Måndag den 19 december 2011, kl 10.00 Plats: F531, Luleå tekniska universitet
Green, Sarah A. "Applications of fluorescence spectroscopy to environmental chemistry." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13167.
Повний текст джерелаSzucs, Andrea. "Geochemical Landscape Analysis for the Risk Assessment of Acid Mine Drainage in a Wetland Environment." Doctoral thesis, Uppsala universitet, Institutionen för geovetenskaper, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6992.
Повний текст джерелаNewman, Sharon Audrey. "Taphonomic studies of fossil preservation in coarse-grained siliciclastic environments." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/115777.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references.
Ediacaran and early Cambrian sandy and silty sediments commonly preserve microbial fossils and textures as well as the fossils of soft-bodied organisms. The rarity of similar fossils and textures in coarse-grained siliciclastic strata of the later Phanerozoic suggests that a taphonomic window facilitated this mode of fossil preservation. However, environmental and biological factors that promoted fossilization remain unclear. To experimentally identify mechanisms of preservation in siliciclastic sediments, cyanobacteria and soft tissues (scallop adductor muscles) were incubated in silica sand or clay minerals for up to two months. Clay mineral veneers coated both cyanobacterial filaments and the surfaces of soft tissues and were formed by two main processes: 1) the adhesion of fine particles from the sediment and 2) the precipitation of authigenic minerals. Photosynthetic, sheathed microorganisms were best preserved in the presence of high concentrations of dissolved silica (>0. 1 mM) and suspended fine particles (>5.6 mg/L) in solution. We showed that these organisms could be preserved in oxic environments and that the degradation of cyanobacteria by heterotrophic microorganisms was not necessary for fossilization. In contrast, soft tissues buried in sand/clay were preserved under anaerobic conditions and mineral veneers around them contained reduced iron. All scallops decayed in the presence of endogenous bacteria and the redox cycling of iron that included the microbial reduction of iron(III). We showed that the early precipitation of silica and the formation of microbial death masks is not critical for preservation. Additionally, when the degradation of soft tissues advanced within the first 15 to 30 days, all soft tissues decayed completely and left no morphological imprint. Taken together, these results show that the early microbial reduction of iron(III) present in sedimentary minerals and the formation of mineral veneers are critical for the preservation of organic material. The same processes may have facilitated the formation of exceptionally preserved fossils and textures throughout the Ediacaran and early Cambrian. Future studies should focus on the roles of iron redox cycling, sediment composition and microbial metabolisms in the preservation of soft tissues to better understand mechanisms for Ediacaran-style preservation in siliciclastic environments.
by Sharon Audrey Newman.
Ph. D.
Nolan, Marie. "Levee stability and the evolution of 'A'a lava flow-fields." Thesis, University of Portsmouth, 2014. https://researchportal.port.ac.uk/portal/en/theses/levee-stability-and-the-evolution-of-a-a-lava-flowfields(d2bf4697-8120-4645-97fa-a2cc1f05b8bb).html.
Повний текст джерелаArgyriou, Athanasios. "A methodology for the rapid identification of neotectonic features using geographical information systems and remote sensing : a case study from western Crete, Greece." Thesis, University of Portsmouth, 2012. https://researchportal.port.ac.uk/portal/en/theses/a-methodology-for-the-rapid-identification-of-neotectonic-features-using-geographical-information-systems-and-remote-sensing(0f0ae683-6170-49f2-b8a6-7e00d821377c).html.
Повний текст джерелаEnea, Cornelia Florentina. "Rutile : a new petrogenetic tool to investigate old subduction zones." Thesis, University of Portsmouth, 2012. https://researchportal.port.ac.uk/portal/en/theses/rutile(a2054ec4-89ca-42a7-ae9e-dcabac80e73c).html.
Повний текст джерелаBrown, Sarah Krystyna. "The distribution and development of eruptive centres and lava flow-field characteristics at Somma-Vesuvius, Italy." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/the-distribution-and-development-of-eruptive-centres-and-lava-flowfield-characteristics-at-sommavesuvius-italy(5ce1bfb2-dc28-4513-b1a4-62d4eaedcff3).html.
Повний текст джерелаTurner, Geraldine Sarah Clinton. "The application of the passive sampling technique diffusive gradients in thin-films (DGT) to the measurement of uranium in natural waters." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/the-application-of-the-passive-sampling-technique-diffusive-gradients-in-thinfilms-dgt-to-the-measurement-of-uranium-in-natural-waters(107c3ce9-2c00-435f-b241-0b668c36bf9b).html.
Повний текст джерелаMcCall, Stephanie Jane. "Investigating the effects of nutrient concentration and light intensity on benthic biofilm development and phytoplankton growth in UK rivers." Thesis, University of Portsmouth, 2014. https://researchportal.port.ac.uk/portal/en/theses/investigating-the-effects-of-nutrient-concentration-and-light-intensity-on-benthic-biofilm-development-and-phytoplankton-growth-in-uk-rivers(5bb096f7-b9fb-4a4f-a714-e2f05271800d).html.
Повний текст джерелаGiles, David. "Computer-based modelling and analysis in engineering geology." Thesis, University of Portsmouth, 2014. https://researchportal.port.ac.uk/portal/en/theses/computerbased-modelling-and-analysis-in-engineering-geology(091c5104-4dbb-4e90-b897-aaf34702100a).html.
Повний текст джерелаYuangdetkla, Kwanjai. "Distribution of landslides and geotechnical properties within the Hampshire Basin." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/distribution-of-landslides-and-geotechnical-properties-within-the-hampshire-basin(ce5ae2ee-9a68-41e2-bdc1-de067dc0b507).html.
Повний текст джерелаBatenburg, Sietske J. "Orbital pacing of Maastrichtian climate : integrated stratigraphy of the Zumaia and Sopelana sections (N-Spain)." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/orbital-pacing-of-maastrichtian-climate(7eb822d4-1fce-4db8-8909-cdac7e65bd91).html.
Повний текст джерелаHeroy, David Carlson. "Sand- and Clay-Size Mineralogy of the Ganges and Brahmaputra Rivers: Records of River Switching and Late-Quaternary Climate Change." W&M ScholarWorks, 2000. https://scholarworks.wm.edu/etd/1539617766.
Повний текст джерелаLima, Ana Lúcia Cessel de 1969. "Molecular and isotopic records of the combustion inputs to the environment over the last 250 yrs." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/39413.
Повний текст джерелаIncludes bibliographical references.
The most ubiquitous source of polycyclic aromatic hydrocarbons (PAHs) to the environment is incomplete combustion. This study generated a high-resolution historical record of pyrogenic PAH emissions since pre-industrial times from anoxic aquatic sediments, allowing for detailed comparison with energy consumption data. We show that an increase in PAH concentrations over the last decade may be due to a rise in emissions from diesel-powered vehicles. Compound-specific radiocarbon measurements demonstrated unequivocally that the proportion of PAHs derived from fossil fuel combustion has increased substantially during the 20th century. [delta]¹³C and [delta]¹⁴C measurements were also used to constrain the relative importance of combustion versus in situ production as sources of perylene. In addition, a comparison of the down-core concentration and isotopic profiles of black carbon (BC) generated by a combination of chemical and/or thermal oxidation methods highlighted the limitations of these methods when applied to sedimentary matrices. Finally, parallel lead and cesium isotopic records revealed two new potential stratigraphic markers in North American sedimentary records. ²⁰⁶Pb/²⁰⁷Pb profiles show a distinct peak in the mid-19th century, while a ¹³⁷Cs peak was found to coincide with the 1986 Chernobyl accident.
by Anna Lúcia Cessel de Lima.
Ph.D.
Maheras, Anastasia Francis. "Elemental and reactive gaseous mercury deposition and diurnal cycles over terrestrial environments." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/114365.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 88-93).
The atmospheric component of the global biogeochemical mercury cycle was studied to determine the mechanisms behind diurnal trends and amplitudes in elemental and reactive gaseous mercury concentrations over terrestrial environments. This analysis was done using the 3D GEOS-Chem chemical transport model and the creation of a simple one-box model. Mercury is a significant neurotoxin for humans and other species that has been addressed in the policy realm on both national and international levels. Being able to model atmospheric mercury processes correctly is an important part of regulation and policy drafting. GEOS-Chem model results were compared with Weiss-Penzias et al. [2009] measurements for three Nevada, USA sites. The magnitude of elemental mercury concentrations differed by 0.07-0.2 ng/m3 , with GEOS-Chem underestimating concentrations due to an under-representation of mercury emissions at naturally enriched sites. The amplitude of reactive gaseous mercury diurnal variations differed by a factor of 3-4, with GEOS-Chem underestimating the diurnal trend. Based on the diurnal nature of this error, it is hypothesized that GEOS-Chem under represents the magnitude of elemental mercury emissions, the amount of oxidation occurring in the atmosphere, and the scale of entrainment from the free troposphere.
by Anastasia F. Maheras.
S.B.
Matys, Emily D. "Environmental controls on the distribution of bacterial membrane lipids." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119985.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references.
Since their discovery in ancient sediments, hopanes and their biological precursors, bacteriohopanepolyols (BHPs), have been of great interest for their potential to serve as proxies for bacteria in the geological record. The validation of these and other biomarkers have implications for understanding the coevolution of organisms and the environment throughout Earth's history. 2-Methylhopanoids are of particular interest because their occurrence may be confined to cyanobacteria and alphaproteobacteria. Similarly, a stereoisomer of bacteriohopanetetrol (BHT), BHT II, has been identified exclusively in anaerobic ammonium oxidation (anammox) bacteria. However, the interpretation of sedimentary hopanoids is presently limited by an incomplete understanding of their phylogenetic associations, biological functions, and spatial and temporal disposition throughout diverse environments. I address some of these shortcomings through lipid biomarker characterization of water column and benthic microbial mat samples collected across geochemical and physiochemical gradients in the Eastern Tropical South Pacific oxygen minimum zone off the coast of northern Chile and in two ice-covered lakes of the McMurdo Dry Valleys, Antarctica. The results will enhance our ability to interpret the molecular fossil record, particularly those biomarkers that might preserve evidence of ancient marine and glacial environments. I will provide evidence that supports the use of BHT II as a biomarker for suboxia/anoxia, confirm the biosynthesis of 2- MeBHT in cyanobacteria as a response to photosynthetic stress, and describe improved methods that allow us to better detect, quantify, and interpret these markers in modern environments.
by Emily D. Matys.
Ph. D.
Maheras, Anastasia Francis. "Assessing United States hurricane damage under different environmental conditions." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78479.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 47-53).
Hurricane activity between 1979 and 2011 was studied to determine damage statistics under different environmental conditions. Hurricanes cause billions of dollars of damage every year in the United States, but damage locations and magnitudes vary from year to year. Seasonal hurricane forecasts predicting the strength of the upcoming hurricane season have the potential to be used by many industries and sectors to reduce and mitigate the effects of hurricanes. However, damage itself is not predicted by these forecasts. This work analyzed trends in hurricane damage due to atmospheric and oceanic conditions, and the results could be applied to and included in seasonal hurricane forecasts, thus increasing forecast applicability and value. This work used synthetic hurricane tracks generated from background climate conditions, a U.S. property portfolio, and a damage function based on wind speed to determine 1979-2011 hurricane damage. Damage was split into La Niña/El Niño and pre-/post- 1995 year sets to determine spatial and temporal trends in U.S. hurricane damage. This work concluded that different regions of the country experienced more or less hurricane damage under different environmental conditions. Knowledge of these trends can be applied to seasonal hurricane forecasts and can influence property owner, regulator, and insurer behavior across the nation.
by Anastasia Francis Maheras.
S.M.in Atmospheric Science
Kempes, Christopher Andrew Poling. "The physical, environmental, and evolutionary determinants of biological architecture." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79281.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 201-224).
The relationship between structure and function is a longstanding and central topic in biology, evolution, and ecology. The importance of morphology is clearly visible in the diverse forms taken by innumerable organisms in order to perform a myriad of functions. Examining the great variety of morphological characteristics it would seem that the overall principle of evolution is the only way to generalize the observed diversity: given differences in environments and random biological variation a great multitude of body plans have been invented as adaptations to many dynamic habitats given specific evolutionary histories. In this thesis I will show how focusing on diverse organisms makes it possible to identify common first-order laws of evolutionary organization. More specifically I will show how these common laws derive from a connection between organism structure, physical limitations, environmental constraints, and basic metabolic, biochemical, or energetic principles. Furthermore, I will show how this top level of biological organization holds significant predictive power for regional ecology and for interpreting the general trends of evolutionary history. In Chapter 2 we begin by deriving a model for the growth of single cells and populations of cells. This model is based on the partitioning of metabolic resources and the scaling relationship between metabolism and body size. We show that the growth of diverse classes of organisms is connected by common unit energetics. However there exist striking differences in the broad trends between growth rate and body size across these different classes and we show that this is a consequence of major evolutionary transitions which adjust the partitioning of metabolic resources. We interpret major evolutionary transitions to occur in response to energetic limitations. We also find that multicellular living for unicellular organisms provides a metabolic and reproductive advantage. In Chapters 3 and 4 we further investigate these features in microbial biofilms which exhibit rich spatial patterning. Using a mathematical model and experimentation we find that the tall vertical structures produced by these biofilms have optimal geometry for resource uptake and the growth efficiency of the entire colony. Our model allows us to predict the observed changes in feature geometry given alterations to the environmental conditions that the biofilms are grown in. Furthermore, we are able to show that the morphology of these structures is dependent on single cell physiology. For example, single genetic knockouts of flagellar motility radically alter the temporal dynamics of feature spacing. Our work highlights morphology as a central property in multicellular organisms which mediates the interaction between environmental conditions and physiology. In Chapter 5 we highlight the importance of morphology in complex multicellular life where we develop a general model of tree architecture which we link to physiological success within a given environment. Although this model is general, uses only tree size as a governing parameter, and does not consider speciation we are able use local resource availability to predict broad regional patterns in plant traits such as maximum tree height. Each of these chapters highlights the importance of structure and morphology at multiple biological scales. In Chapter 6 we show how the importance of structure extends to the genetic level where the specific encoding of a gene can have implicit information and functionality beyond the basic translation of codons. We investigate the observed implicit function of dramatic and frequent changes in the mutation rate of an organism given the structure of the mutL gene. We show mathematically that altering mutation rates is an evolutionarily advantageous strategy, and we show bioinformatically that the specific genetic structure that gives rise to this trait is under positive evolutionary selection.
by Christopher Andrew Poling Kempes.
Ph.D.in Physical Biology
Jackson, Randolph L. "Collaboration and learning within tele-immersive virtual environments /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7869.
Повний текст джерелаMolitor, Edvard. "Miljöfarliga transporter till sjöss : Kartläggning och riskanalys." Thesis, Uppsala University, Department of Earth Sciences, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88854.
Повний текст джерелаAn increasing number of chemicals are being transported by ships along the Swedish coastline. Many of these chemicals may pose a threat to the environment. Accidents and spills are luckily rare, but nonetheless it is important to be prepared for a possible chemical spill. The Swedish Coast Guard is responsible for responding to chemical spills at sea, and has both equipment and trained personnel for the purpose. In order to prepare for a possible accident one also needs to know what is currently being transported at sea. The aim of this project is therefore to survey the chemical transports in Swedish waters.
The survey shows that many of the chemicals transported at sea are environmentally harmful and may harm the environment in the event of a spill. The number of accidents that occur is difficult to determine since not all of the smaller ones are reported. It is clear, however, that the main reasons for accidents are groundings and collisions. The collection of information about chemical transports has been difficult because many of the companies and ports are unwilling to give their information. This is part because of concurrence and part due to the fact that it is considered too much work to gather the data.
The project also aims to make a risk analysis for chemical transports at sea. Because of the insufficient data the risk analysis has only dealt with qualitative assessments for certain chemicals. These assessments show that chemicals which are less environmentally harmful may still pose a threat because of the safety issues for the personnel may delay or even prevent a response action.
International regulations for transports at sea can sometimes be complicated to apply because of the vast number of different chemicals. The classification process takes time because of the extensive research which is needed. Furthermore, many of the chemicals transported are classified in different systems and these do not always correspond. It is therefore difficult to conclude which chemicals that are actually a threat to the environment.
Varje år transporteras allt större mängder kemikalier med fartyg längs Sveriges kust. Många av dessa kan vara farliga för miljön. Olyckor och utsläpp sker lyckligtvis ganska sällan men det krävs ändå en beredskap för att kunna ta hand om ett eventuellt utsläpp. I Sverige har Kustbevakningen ansvaret för miljöräddningstjänst till sjöss och har både utrustning och personal som är speciellt utbildad för att bekämpa just kemikalieutsläpp. För att kunna förbereda sig på en eventuell olycka måste man dock också ha en aktuell bild av vilka kemikalier det är som transporteras till sjöss. Detta projekt har därför syftat till att kartlägga kemikalietransporterna i svenska farvatten.
Kartläggningen visar att flera av de kemikalier som transporteras till sjöss är miljöfarliga och kan skada miljön vid ett utsläpp eller en olycka. Hur många olyckor som sker är svårt att veta eftersom många av de mindre olyckorna inte rapporteras. Däremot kan man tydligt se att de vanligaste olycksorsakerna är kollisioner och grundstötningar. Att få tag i uppgifter om hur mycket kemikalier som transporteras har visat sig vara svårt eftersom flera företag och hamnar inte vill tala om hur mycket som transporteras. Det beror dels på konkurrensen mellan kemikalieföretag och dels på att man tycker att det är för jobbigt att behöva sammanställa informationen.
Projektet har också syftat till att göra en riskanalys över kemikalietransporterna. På grund av det bristfälliga underlaget har riskanalysen endast behandlat kvalitativa bedömningar av ett antal olika kemikalier. Dessa bedömningar visar att även kemikalier som är mindre miljöfarliga kan utgöra en stor risk eftersom de säkerhetsmässiga riskerna för insatspersonalen kan försena eller till och med förhindra en bekämpningsinsats.
De internationella reglerna kring transporter till sjöss kan ibland vara svåra att tillämpa eftersom det finns ett stort antal olika kemikalier. Klassningen av de olika kemikalierna tar också lång tid då det krävs omfattande underlag. Många av kemikalierna som transporteras är dessutom klassade enligt flera olika system och det är inte alltid dessa system överensstämmer. Det kan därför vara svårt att ta reda på vilka kemikalier som egentligen kan anses vara miljöfarliga.