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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Dendrochronology of Bristlecone Pine

Ferguson, C. W., Graybill, D. A. 31 October 1981 (has links)
"A Terminal Report Submitted 31 October, 1981 on the National Science Foundation grant EAR 78-04436 with the assistance of the Department of Energy contract no. EE-78-A-28-3274"
2

Dendrochronology of Bristlecone Pine

Ferguson, C. W., Graybill, D. A. 31 May 1985 (has links)
"A Final Technical Report Submitted 31 May 1985 on the National Science Foundation grant EAR-8018687 for the period 1 April 1981 to 31 October 1984 with the assistance of the Department of Energy contract no. DE-AC02-81EV10680 covering the period 1 May 1981 to 31 October 1982" / Since Edmund Schulman’s initial interest in 1953, the Laboratory of Tree-Ring Research has conducted dendrochronological studies of bristlecone pine (Pinus longaeva D. K. Bailey, sp. Nov.) in the White Mountains of east-central California where living trees reach ages in excess of 4,000 years. The focus of this report relates to the support by the Geology and Anthropology sections in the National Science Foundation under grant EAR-8018687 for the period 1 April 1981 to 31 October 1984 with the assistance of the Department of Energy contract no. DE-AC02-81EV10680 covering the period 1 May 1981 to 31 October 1982. A summary of this research was recently published in Radiocarbon (Ferguson and Graybill 1983). In most cases various facets of the work were related to projects sponsored by all agencies. Therefore the full range of activities during that period is described herein. The primary project goals were: To extend the bristlecone pine chronology from the White Mountains of California beyond 6700 B.C. and strengthen it by incorporating additional specimens. To develop bristlecone pine chronologies in new areas for applications in archaeology, isotopic studies, and other earth sciences. To furnish dendrochronologically dated wood to researchers engaged in the study of past variations in carbon isotopes and climate.
3

Impatto e prevenzione dell'inquinamento delle acque sotterranee da pesticidi e nitrati nei vigneti collinari: valutazione delle fonti di contaminazione e sviluppo delle migliori pratiche di gestione e misure di mitigazione / IMPACT AND PREVENTION OF GROUNDWATER POLLUTION BY PESTICIDES AND NITRATE IN HILLY VINEYARDS: EVALUATION OF CONTAMINATION SOURCES AND DEVELOPMENT OF BEST MANAGEMENT PRACTICES AND MITIGATION MEASURES / Impact and prevention of groundwater pollution by pesticides and nitrate in hilly vineyards: evaluation of contamination sources and development of best management practices and mitigation measures

ZAMBITO MARSALA, ROBERTA 28 April 2021 (has links)
Molte attività antropiche danno origine a problemi ambientali per i quali è necessario trovare soluzioni. La presenza di sostanze indesiderabili nell'acqua, infatti, può rappresentare un rischio per la salute e l'igiene sia degli uomini che degli animali. È quindi fondamentale trovare metodi per evitare gli inquinanti di queste matrici, in modo da renderli compatibili con il mantenimento di condizioni ambientali adeguate e salutari. Questa tesi si propone di valutare la qualità delle acque sotterranee di un'area in cui la qualità dell'acqua non è mai stata studiata, in particolare indagando la presenza di pesticidi e nitrati al fine di comprendere l’impatto della viticoltura sull'inquinamento delle acque sotterranee. Questo studio nasce dalla necessità di migliorare la governance delle acque e di implementare le migliori pratiche di gestione e misure di mitigazione per prevenire l'inquinamento delle acque e quello ambientale. I risultati degli studi di monitoraggio hanno mostrato una contaminazione delle acque sotterranee da parte di pesticidi e nitrati e quindi è stata effettuata una valutazione della fonte di contaminazione da pesticidi e nitrati attraverso studi isotopici di N e O di NO3-, e attraverso analisi idrologiche utilizzando il modello CRITERIA 3D. Come una delle principali conclusioni del lavoro si può affermare che la presenza di pesticidi nelle acque sotterranee in un’area ad attività vitivinicola intensa, non può essere correlata solo alle proprietà e al destino chimico-ambientale delle sostanze o alle condizioni pedoclimatiche, ma anche al comportamento dell'utilizzatore finale. In effetti, la fonte di contaminazione valutata, è risultata essere dovuta sia a una contaminazione diffusa che a una contaminazione puntiforme. Per quanto riguarda l'influenza della fertilizzazione a base di azoto sulla presenza di nitrati nelle acque sotterranee, i risultati hanno mostrato un'elevata vulnerabilità dell'acquifero ai cambiamenti esterni. Dalle indagini isotopiche è emerso che la maggior parte dell'NO3- rilevato nelle acque sotterranee, deriva dall'utilizzo di fertilizzanti azotati inorganici, in accordo con le pratiche di uso del suolo e di viticoltura dichiarate dagli agricoltori della zona. Il risultato più importante dello studio, tuttavia, è stato che alla fine del processo, l'approccio multi-actor e la strategia di coinvolgimento adottati, hanno avuto successo nel migliorare gli atteggiamenti verso pratiche più sostenibili. / Many anthropic activities give rise to environmental problems for which it is necessary to find solutions. The presence of undesirable substances in water, indeed, can pose a risk to the health and hygiene of both men and animals. It is, therefore, essential to find methods in order to avoid pollutants from these matrices, so as to make them compatible with the maintenance of healthy environmental conditions. This thesis aims to assessing the groundwater quality of an area in which the quality of water was never studied, particularly investigating the occurrence of pesticides and nitrate in order to understand the grant of viticulture on water pollution. This study derives from the necessity to improve the water governance and to implement the best management practices and mitigation measures to prevent groundwater and environmental pollution. The results of monitoring studies showed a contamination of groundwater by pesticides and nitrate and thus an evaluation of PPPs and nitrates source contamination was carried out through isotopic studies of N and O of NO3- , and through hydrologic analysis by use of the model CRITERIA 3D. As one of the main conclusions of the work, the occurrence of PPPs in groundwater in areas with intensive viticultural activities cannot be related just to chemical environmental fate properties or pedoclimatic conditions, but also to end-user behavior. In fact, the contamination source evaluated, resulted to be due to both diffuse and point-source contamination. For what concerns the influence of nitrogen-based fertilization on nitrate occurrence in groundwater, the results showed a high vulnerability of the aquifer to external changes. Isotopic investigations showed that most of the NO3- detected in the groundwater, derived from the use of inorganic nitrogen fertilizers, in agreement with the land use and viticulture practices declared by the farmers. The most important result of the study, however, was that at the end of the overall process, the multi-actor approach and engagement strategy adopted were successful in improving attitudes to more sustainable practices.
4

THE IMPACT OF REFUSE ON THE KELP GULL (LARUS DOMINICANUS) IN THE RÍO DE LA PLATA ESTUARY, URUGUAY

Cesar J. Lenzi (5929943) 04 January 2019 (has links)
<p>Modern economic activities, like industry and agriculture, as well as household activities, generate an important amount of refuse. The way we collect, transport, and dispose it will determine the level of environmental contamination. May animals exploit refuse as a food source (i.e., anthropogenic food subsidy) and gulls are the most important group. Refuse subsidizes energetically gull populations, which impacts on their acquisition and allocation of resources, as well as on the environment, with ecological and evolutionary consequences are not well understood. In this dissertation we evaluated potential impacts of refuse on gulls by doing a literature review as well as empirical research on the Kelp Gull (<i>Larus dominicanus</i>) in the Rio de la Plata Estuary in South America. Direct and indirect impacts of refuse on gull species and the environment have been observed during the review process. We have detected positive impacts of refuse on body size, chick growth, fecundity, reproductive success, and population dynamics. However, negative impacts were also found focusing on fecundity, reproductive success, and population dynamics. Indirect negative impacts on other species, water bodies, and airport security were also found. Refuse produces numerous impacts on gulls at the individual, population, and species levels, with indirect negative consequences on ecosystems. There is a need to reduce the access of gulls to sources of refuse to mitigate the existing and potential conflicts with human activities and other species, especially those that are threatened and endangered. During our empirical research we found that refuse was ingested and assimilated by Kelp Gull chicks during the chick rearing period and that the ecological niche width increased with the age of the chick. We propose that parents incorporate isotopically unique food sources to nestling’s diet during their growth, increasing isotopic diversity of nestlings. Additionally, we found that refuse could affect foraging decisions of females during the pre-incubation period, which could positively affect future fecundity and negatively impact reproductive success. We found also that refuse consumption on fecundity and reproductive success of gulls is generally studied at the colony level, using conventional diet techniques, but not much has been done using stable isotopes at the individual level, making comparisons among studies and conclusions difficult to address. We encourage other researchers to continue incorporating the isotopic ecology perspective to study the effect of food subsidies on gulls. Additionally, we found that Kelp Gull on the coast of the Rio de la Plata Estuary ingest plastic debris. We conclude that plastic bags and plastic films might be the most important source of contaminants for the Kelp Gull on the coast of the estuary. Main findings of this dissertation suggests the need for an improvement of waste management practices and a regulation of plastic production and use in Uruguay to reduce plastic ingestion by gulls. Finally, next steps for research are provided in this important area of environmental science and natural resource management.</p>

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