Les tourbières couvrent 3 % des surfaces continentales et jouent un rôle important dans le cycle du carbone en stockant le tiers du carbone des sols. L'accumulation de tourbe est liée au déséquilibre production primaire/décomposition du à une activité microbienne limitée par les conditions environnementales. L'infection et la lyse virale ont un impact sur la diversité et l'activité des communautés microbiennes, et influent sur le cycle du carbone. Cependant, le fonctionnement de ce compartiment viral n'avait jamais été pris en compte dans les études de fonctionnement des tourbières. Le but de ce travail de thèse était d'analyser et comprendre la dynamique spatiale et temporelle de l'abondance et de la diversité virale des tourbières à Sphagnum. L'analyse de l'abondance virale et procaryote et de 12 metaviromes en lien avec la physico-chimie d'une tourbière tempérée en France montre une forte variation saisonnière des communautés virales. Cette variation semble très liée aux conditions environnementales générées par la fluctuation de la nappe d'eau. Dans cette même tourbière, l'analyse de la diversité taxonomique et fonctionnelle des communautés de microorganismes présents (métagénomes) et métaboliquement actifs (métatranscriptomes) indique que la structure taxonomique est différente entre les des deux principaux stades, le fen et le bog, mais que ces communautés présentent une diversité fonctionnelle similaire, dont l'expression est liée aux changements des conditions environnementales avec la profondeur. L'abondance des particules virales étudiées dans 5 tourbières à Sphagnum réparties en Finlande, au Canada, en France, et sur l'île subantarctique d'Amsterdam varie fortement avec les sites. L'analyse de la diversité virale de la matrice et de l'eau de tourbe du Canada et de Finlande montre que la diversité virale est structurée par le site, puis le stade dynamique, puis la profondeur, avec un rôle important de la saturation en eau au niveau du site. Ces résultats valident le fonctionnement proposé du compartiment viral et de la communauté d'hôtes procaryotes. Ces connaissances ont été utilisées pour analyser le fonctionnement du compartiment microbien de tourbières à Sphagnum soumises à des perturbations d'origine anthropique. Les 31 métaviromes produits pour cette thèse constituent l'une des plus grandes bases de données sur la diversité virale des écosystèmes alors que la diversité virale des sols n'avait presque jamais été étudiée auparavant. / Peatlands cover 3 % of the continental surfaces but represent up to a third of the soil carbon stock. Peat accumulation results from the imbalance between primary production and decomposition due to the limitation of the prokaryote activity caused by the environmental conditions. Viral infection and lysis impact the diversity and the activity of the microbial communities and influence the carbon cycle. However, the functioning of the viral compartment had never been taken into account in peatlands. The aim of this thesis was to gain knowledge about the spatio-temporal dynamic of viral abundance and diversity in Sphagnum-dominated peatlands. Spatio-temporal analysis of viral and prokaryote abundance and of 12 metaviromes (viral diversity) in relation to the physico-chemical features in a temperate Sphagnum-dominated peatland in France revealed the high seasonal variability of the viral communities. This dynamic appeared mainly related to the environmental conditions shaped by the fluctuation of the water-table level. In the same peatland the taxonomic diversity of the present microorganisms (metagenomes) differed between the fen and the bog, but these communities present a similar functional diversity, which expression in selected in the same way in the two dynamic stages, in relation to depth-related environmental conditions. Viral abundance analyzed in 5 Sphagnum-dominated peatlands from Finland, Canada, France and subantarctic Amsterdam Isle presented a high geographical variability. Investigation of the diversity of the viral communities from the peat matrix and the pore-water in Finland and Canada emphasized the structuration of the viral communities by the site, then the dynamic stage, and finally depth. These results confirm the first hypotheses about the functioning of the viral compartment depending on environmental conditions and prokaryote activity. Effects of human-derived disturbances on viral ecology in peatlands were investigated based on this knowledge. While soil viral diversity was poorly documented at the start of this thesis, the collection of 31 metaviromes from Sphagnum-dominated peatlands produced for this project represents the second largest dataset representing the viral diversity from environmental samples.

The primary focus of this project is with the interaction between nature and people. How did the Obispeno Chumash affect their surroundings and what was the outcome? Did changes occur in the environment when other people took over the care of the land? Over the last 250 years, the Obispeno Chumash land has evolved from an ecologically green dominion under their stewardship to the present day where the area is noted for its mission, recreational value, wealth of opportunity, and a nuclear power plant located between Morro Bay and Point Buchon along the ocean.

This study uses the storm surge sediment beds deposited by Hurricanes Audrey (1957), Carla (1961), Rita (2005) and Ike (2008) to investigate spatial and temporal changes in sedimentation rates on the McFaddin National Wildlife Refuge in Southeast Texas. Fourteen sediment cores were collected along a transect extending from 90 to 1230 meters inland from the Gulf Coast. Storm-surge-deposited sediment beds were identified by texture, organic content, carbonate content, the presence of marine microfossils, and Cesium-137 dating. The hurricane-derived sediment beds are marker horizons that facilitate assessment of marsh sedimentation rates from nearshore to inland locations as well as over decadal to annual timescales. Near the shore, on a Hurricane Ike washover fan, where hurricane-derived sedimentation has increased elevation by up to 0.68 m since 2005, there was no measurable marsh sedimentation in the period 2008-2014. Farther inland, at lower elevations, sedimentation for the period 2008-2014 averaged 0.36 cm per year. The reduction in sedimentation in the period 2008-2014 on the nearshore part of the marsh is likely due to reduced flooding in response to increased elevation from hurricane storm surge sediment deposition. These results provide valuable knowledge about the sedimentary response of coastal marshes subject to storm surge deposition and useful guidance to public policy aimed at combating the effects of sea level rise on coastal marshes along the Gulf of Mexico.

Land degradation has been a global agenda. It has been affecting both developed and developing nations (including Ethiopia). The overall objective of the study was to assess the impact of landscape restoration (including area closure) on the environment and farmers‘ livelihood in Hita-Borkena watershed, northeastern Ethiopia. Three Landsat images (1986, 2001 and 2015) were used to detect land cover dynamics. Laboratory analysis of selected soil physico-chemical properties were made to compare the soil properties of closed/restored and open grazing areas. Household questionnaire was administered to investigate environmental problems before and after landscape restoration, the role of area closure and different conservation measures, and the impact of the restoration on farmers‘ livelihood. A total of 255 household heads were selected randomly for the questionnaire survey. This survey was also substantiated by interviewing agricultural experts, observation and reviewing reports prepared by Kalu District Agriculture Office. Both descriptive and inferential statistics were employed to analyze quantitative data. Besides, qualitative approach was implemented in order to analyze qualitative data. The study found out that forestlands and shrublands shrunk through 1986 – 2015, grasslands expanded mainly due to the implementation of area closure under MERET project since 2001. The study revealed that better organic matter, total nitrogen, clay and silt contents, CEC and total porosity were recorded under area closure than under open grazing land. However, both available P and K were found minimum under the former land use type. This may be due to the reason that such nutrients exist more in unavailable form or it may be because of the fact that large amount of those nutrients are extracted by the restored vegetation. The study showed that rates of soil erosion, overgrazing and illegal cutting of trees were relatively higher before landscape restoration. The respondents also appreciated the positive role of land restoration in improving the fertility of the soils of the study watershed and then the positive impact to their livelihood. Based on the results of the study, it is recommended that similar restoration activities shall be implemented in similar environments in Ethiopia to improve both the environment and farmers‘ livelihood / Geography / Ph. D. (Geography)

The purpose of this study was to explore and describe the EcoHealth markers and health promotion interventions in the behaviour and practices of vegetables growers in Addis Ababa. The objectives were to assess the urban and peri-urban community members’ knowledge and practices on the existing environmental health policies/regulations/guidelines, assess the perspectives of women and youth on urban and peri-urban EcoHealth promotions and protections and evaluate the development and implementation of the health promotion activities on waste water use by applying an ecological model aimed at changing behaviour and by providing Bio-sand filter to promote hand wash practice which helps to reduce potential health risks among urban vegetable growers. Both quantitative and qualitative descriptive researches were conducted to identify the urban and peri urban community members’ knowledge and practices of the existing environmental health regulators and the perspectives of women and the youth on EcoHealth. Additional quasi experimental method; multiple baseline survey along with the EcoHealth Stress Process promotion method was employed to identify stressors, measure changes in environmental health promotion intervention and use of hand wash (biosand filter for hand wash). Six woredas from two subcities of the Addis Ababa City Administration were purposely selected, and a total of 845 (98.9% response rate) households participated in the quantitative study, while 142 community members (public sector offices, factories and establishments’ management and employee), participated in the qualitative survey. For quasi experimental method, six settings/blocks (of which 3 sites were provided with a bio-sand filter for hand washing) cultivated by 6 to 8 vegetable growers and their family members, were included in the intervention (multiple baseline survey). The findings revealed that about 77 percent of participants reported, knowledge of one or more of the selected environmental health and EcoHealth regulations. Ownership of assets and education tend to influence the public awareness of selected EcoHealth and environmental health regulations. Women and youth found to be significant contributors to better urban and peri-urban EcoHealth conditions and were the ones primarily affected by environmental hazards. The intervention study results also indicated evidence-based IEC interventions and ecological health promotion methods proved useful in promoting EcoHealth in an urban environment. Moreover, the biosand filter used to provide evidence of health promotion was found to be valuable for wastewater treatment and significantly reduced chemical, physical and biological contaminates from the wastewater. / Health Studies / D. Litt. et Phil. (Health Studies)

[ES] La adición de fibras a la matriz cementicia ha sido una práctica común desde los años sesenta para mejorar las propiedades de los hormigones tradicionales. Con el tiempo, los avances en la tecnología han llevado a la introducción de varios tipos de fibras en el mercado, dado lugar a diferentes tipos de hormigones reforzados con fibras (FRC). En comparación con las fibras de acero, las macro- fibras sintéticas han aparecido recientemente. A pesar de los estudios sobre su comportamiento, no se ha estudiado exhaustivamente cómo la temperatura afecta al hormigón reforzado con macro-fibras sintéticas (MSFRC). El uso de MSFRC podría promoverse siempre y cuando se llevaran a cabo más investigaciones sobre su comportamiento para verificar su desempeño. El propósito de esta Tesis surge de la necesidad de comprender el comportamiento mecánico del MSFRC bajo temperaturas y aclarar ciertas implicaciones, como el efecto de la prefisuración en su envejecimiento (por temperatura). Este trabajo analiza el comportamiento a corto (3 días de exposición) y largo plazo (90 y 180 días de exposición) de tres tipos de MSFRCs y un hormigón reforzado con fibras de acero (SFRC) bajo diferentes condiciones ambientales extremas (temperaturas que oscilan entre -15 y 60 °C). Además, se evalúa el comportamiento de una macro-fibra sintética comercial, a nivel de filamento (de -30 a 140 °C) y también se estudia la interacción entre la fibra y la matriz a meso-escala (de -30 a 40 °C). Para su investigación, se han utilizado diferentes metodologías: compresión en cubos de 150 mm de lado y ensayos de flexión a tres puntos en vigas de 150 × 150 × 600 mm, ensayo uniaxial en fibras y en cilindros entallados de 150 × Ø125 mm. Todos estos ensayos se realizaron bajo las temperaturas objetivo. Los resultados muestran que las propiedades de la fibra estudiada dependen de la temperatura. Además, la temperatura y del tiempo de exposición afectan las propiedades mecánicas analizadas de los MSFRCs, pero estos efectos no son muy importantes. Estos resultados están respaldados por un estudio estadístico que, a su vez, ha permitido desarrollar una aproximación numérica sim-ple a las propiedades mecánicas del FRC cuando se diseña para condiciones ambientales extremas a lo largo del tiempo. Esta Tesis promueve la comprensión de los FRCs, particularmente los MSFRCs, mejorando la confianza en su aplicación en proyectos de ingeniería civil. / [CA] L'addició de fibres a la matriu cimentosa ha sigut una pràctica comuna des dels anys seixanta per a millorar les propietats dels formigons tradicionals. Amb el temps, els avanços en la tecnologia han portat a la introducció de diversos tipus de fibres en el mercat, resultant en diferents tipus de formigons reforçats amb fibres (FRC). En comparació amb les fibres d'acer, les macro- fibres sintètiques han aparegut recentment. Malgrat els estudis sobre el seu comportament, no s'ha estudiat exhaustivament com la temperatura afecta al formigó reforçat amb macro-fibres sintètiques (MSFRC). L'ús de MSFRC podria promoure's sempre que es dugueren a terme més investigacions sobre el seu comportament per a el seu acompliment. El propòsit d'esta Tesi sorgix de la necessitat de comprendre el comportament mecànic del MSFRC sota temperatures no estàndard i aclarir unes certes implicacions, com a elements MSFRC prefissurats i no prefissurats, en termes d'envelliment (per temperatura). Este treball analitza el comportament a curt (3 dies d'exposició) i llarg termini (90 i 180 dies d'exposició) de tres tipus de MSFRCs i un formigó reforçat amb fibres d'acer (SFRC) baix diferents condicions ambientals extremes (temperatures que oscil·len entre -15 i 60 °C). A més, s'avalua el comportament d'una fibra comercial tipus II, a nivell de filament (de -30 a 140 °C) i també s'estudia la interacció entre la fibra i la matriu a meso-escala (de -30 a 40 °C). Per al seu investigació, s'han utilitzat diferents metodologies: compressió en cubs de 150 mm de costat i assajos de flexió en tres punts en bigues de 150 × 150 × 600 mm, assaig uniaxial en fibres i en cilindres dentats de 200 × Ø125 mm. Tots estos assajos es van realitzar en condicions de servici, és a dir, a les temperatures objectiu. Els resultats mostren que les propietats de la fibra estudiada depengen de la temperatura. A més, la temperatura i el temps de exposició són factors importants en les propietats mecàniques analitzades dels MSFRCs. Estos resultats estan recolzats per un estudi estadístic que, al seu torn, ha permés desenvolupar una aproximació numèrica simple a les propietats mecàniques del FRC quan es dissenya per a condicions ambientals extremes al llarg del temps. Esta Tesi promou la comprensió dels FRC, particularment els MSFRC, que poden millorar la confiança en l'aplicació de MSFRC en projectes d'enginyeria civil. / [EN] Adding fibers into concrete-matrix has been a common practice since the sixties to enhance the properties of traditional concretes. Over time, advancements in construction sector have led to the introduction of various fiber types into the market, resulting on different types of Fiber Reinforced Concretes (FRCs). Unlike steel fibers, macrosynthetic fibers are a more recent addition. Despite studies on their behavior, there has not been investigated deeply how temperature affects macrosynthetic fiber reinforced concrete (MSFRC). The use of MSFRC could be promoted as long as further investigations into their behavior were carried out to verify their performance and mitigate mistrust. The purpose of this Thesis comes from the need to understand the mechanical behavior of MSFRC under non-standard temperatures and to clarify certain implications, as pre-cracking state of MSFRC elements in terms of aging (by temperature). This work analyzes the short- (3 days of exposure) and long-term (90 and 180 days of exposure) behavior of three types of MSFRCs and one steel fiber reinforced concrete (SFRC) at different extreme environmental conditions (temperatures ranging from -15 to 60 °C). Additionally, the behavior of a commercial macro synthetic fiber is evaluated at single-fiber level (from -30 to 140 °C) and the interaction between fiber and matrix is also studied at meso-scale (from -30 to 40 °C). Different methodologies have been used to investigate herein: compression tests in 150 mm side cubes and three-point bending tests in 150 × 150 × 600 mm beams, uniaxial tests on individual fibers and on notched cylinders of 150 × Ø 125 mm. All these tests were performed in specimens at service conditions, that is, tested at the target temperatures, making a total of 186 cubes, 434 beams, 210 fibers and 30 cylinders. The results show that properties of the studied fiber are dependent on temperature. Additionally, temperature and time of exposure affect mechanical properties of MSFRCs, but their effects are not to a great extent. These results are supported by a statical study which, in turn, have allowed to develop a simple numerical approach to the mechanical properties of FRC when designing for extreme environmental conditions over time. This Thesis advances the understanding of the FRCs, particularly MSFRCs, which may be improved their use in some civil engineering applications. / Caballero Jorna, M. (2024). Study of the Influence of Extreme Environmental Conditions on the Behavior of Macrosynthetic Fiber Reinforced Concretes [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/207918

羅杜芳. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 210-215) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in Chinese and English. / Luo Dufang.

Information regarding the ecological wellbeing of the Natalspruit and its adjoining wetlands is essential if the river is being managed using sound ecological management principles. Despite this, little is known about this river, with little documentation at the regional or municipal level. This study partially addresses this knowledge gap by evaluating the impacts of human activity on a section of the Natalspruit and its adjoining wetlands. It reports on pollution concentrations found at selected sample sites and compares the results to Rand Water data and the National Standards and Guidelines of South Africa for physicochemical parameters and contaminated soils. Water samples were collected at five chosen sample sites during May and July 2018. Soil samples were taken during July 2018. The study found that water at all five sample sites is not suitable for drinking, the health of livestock and recreational use due to the present and high Total Coliform levels (ranging from 450 CFU/100ml to 100 000 CFU/100ml), as well as Turbidity, Total Hardness, TDS, Mg, NO2, SO4, and BOD which also exceeded the guidelines. Only site SS1 (May) exceeded the CaCO3 concentrations regarding livestock health. No guidelines were available for DO levels on the health of livestock. Cl levels in the Natalspruit was suitable for drinking. PO4 concentration at all the sites were all within the guidelines of acceptable levels for aquatic ecosystems. In terms of heavy metals, Cr levels significantly exceeded the guidelines at all five sample sites with the exception of ecosystem health. This is of great concern due to the toxicity of Cr. Cu concentrations exceeded the guidelines for both all land-uses protective of water resources and ecosystem health, at SS1, SS2, SS3 and SS5. Ni concentrations exceeded the guidelines for all land-uses protective of the water resources at SS5. Pb and Zn concentrations exceeded the guidelines for the land-uses protective of the water resources at all the sites with the exception of SS4 for Pb and SS2 and SS4. SS1 and SS5 reported Zn concentrations higher than the guideline for the protection of ecosystem health. SASS 5, PES and EIS assessments indicated moderate to severe modifications of the river. Thus, mining, industrial activities, surface runoff from densely populated informal settlements and wastewater treatment plants have negatively impacted upon the river. Decades of environmental neglect and effluent discharge have degraded the ecosystem, thus necessitating rehabilitation. However, as the study was limited in both time and scope, so additional research should be undertaken. / Environmental Sciences / M. Sc. (Environmental Management)

Indiana University-Purdue University Indianapolis (IUPUI) / Riparian buffers have well documented capacity to remove nitrate (NO3-) from runoff and subsurface flow paths, but information on field-scale N2O emission from these buffers is lacking. This study monitored N2O fluxes at two agricultural riparian buffers in the White River watershed (Indiana) from December 2009 to May 2011 to assess the impact of landscape and hydrogeomorphologic factors on emission. Soil chemical and biochemical properties were measured and environmental variables (soil temperature and moisture) were monitored in an attempt to identify key drivers of N2O emission. The study sites included a mature riparian forest (WR) and a riparian grass buffer (LWD); adjacent corn fields were also monitored for land-use comparison. With the exception of net N mineralization, most soil properties (particle size, bulk density, pH, denitrification potential, organic carbon, C:N) showed little correlation with N2O emission. Analysis of variance (ANOVA) identified season, land-use (riparian buffer vs. crop field), and site geomorphology as major drivers of N2O emission. At both study sites, N2O emission showed strong seasonal variability; the largest emission peaks in the riparian buffers (up to 1,300 % increase) and crop fields (up to 3,500 % increase) occurred in late spring/early summer as a result of flooding, elevated soil moisture and N-fertilization. Nitrous oxide emission was found to be significantly higher in crop fields than in riparian buffers at both LWD (mean: 1.72 and 0.18 mg N2O-N m-2 d-1) and WR (mean: 0.72 and 1.26 mg N2O-N m-2 d-1, respectively). Significant difference (p=0.02) in N2O emission between the riparian buffers was detected, and this effect was attributed to site geomorphology and the greater potential for flooding at the WR site (no flooding occurred at LWD). More than previously expected, the study results demonstrate that N2O emission in riparian buffers is largely driven by landscape geomorphology and land-stream connection (flood potential).