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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

Resíduos sólidos bentônicos em ambientes recifais de Pernambuco e na abordagem das operadoras de mergulho

Spengler, Ângela 31 January 2009 (has links)
Made available in DSpace on 2014-06-12T22:58:21Z (GMT). No. of bitstreams: 2 arquivo1439_1.pdf: 475121 bytes, checksum: 82e04eb0fcc548ed3a876b624848b8ff (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Resíduos sólidos marinhos bentônicos são aqueles resíduos que se depositam no fundo dos oceanos. Estudos sobre esse tipo de poluente ainda são escassos em todo o mundo, tanto estudos de quali-quantificação quanto sobre a compreensão de como os atores sociais ligados ao meio marinho se comportam em relação a esse problema. Para tanto, o presente estudo teve como objetivos quali-quantificar os resíduos sólidos bentônicos em dois tipos de ambientes recifais da costa de Pernambuco, Brasil (um recife semi-submerso exposto a um alto grau de urbanização e exploração turística, localizado na praia da Boa Viagem, Recife; e um recife costeiro submerso em uma região pouco urbanizada e com pouca atividade turística, localizado em frente à foz do Rio Goiana, norte do estado). Outro objetivo foi avaliar a abordagem de escolas e operadoras de mergulho de Pernambuco em relação à poluição marinha, principalmente aquela gerada por resíduos sólidos. Em 28 amostragens realizadas no recife semi-submerso da Boa Viagem, um total de 11.261 resíduos foi observado, sendo a maioria plástico. Resíduos presos no recife, areia ou macroalgas são diferentes daqueles observados livres sobre o recife. A praia adjacente foi considerada como a principal fonte de resíduos para o recife estudado. No recife submerso próximo à foz do Rio Goiana foram amostrados 27 transectos, nos quais nenhum resíduo sólido submerso foi observado. Foram identificadas áreas com potencial para reter resíduos. Foram realizadas entrevistas com proprietários ou funcionários de 14 escolas/operadoras de mergulho. Foram observados diferentes comportamentos em relação à prevenção e remediação da poluição por resíduos sólidos. Através do presente estudo ficou evidenciado a necessidade de expandir os estudos sobre resíduos sólidos marinhos na costa do Brasil, incluindo também outros ambientes além das praias. Recifes costeiros submersos e semi-submersos devem ser incluídos também nos planos de limpeza e gerenciamento de poluição marinha. Estudos em locais ainda sob baixo impacto antrópico também devem ser ampliados, para haver dados de base para trabalhos futuros. Os atores sociais envolvidos diretamente com o ambiente marinho, dentre eles as escolas/operadoras de mergulho, precisam entender melhor o seu papel nas mudanças que devem ser feitas, passando de passivos a ativos nos processos de gerenciamento do ambiente costeiro
2

Marine Geophysical and Geomorphic Survey of Submerged Bronze Age Shorelines and Anchorage SItes at Kalamianos (Korphos, Greece)

Dao, Peter 10 1900 (has links)
<p>The modern coastline provides few clues as to the ancient harbour configuration since Kalamianos has been partially submerged by > 6 m of relative sea-level rise since the Early Helladic. In 2009, a detailed marine geophysical survey and underwater diver search was conducted in the inshore waters to identify potential anchorage sites and to examine evidence for coastal subsidence. Single-beam bathymetry and magnetic gradiometer data were acquired and integrated within a detailed digital bathymetric model (DBM).</p> <p>The DBM revealed two submerged beachrock platforms (BR-1, BR-2) paralleling the modern shoreline and a submerged isthmus connecting the mainland with small island 200 m offshore. The BR-1 platform (3.5-3.7 m depth) contained abundant Late Helladic (LH; 1300-1190 BC) pottery sherds (30-50%) and wood charcoal fragments.<sup>14</sup>C dating of the extracted charcoal yielded an AMS <sup>14</sup>C uncalibrated age of 3250±40 BP, consistent with the LH ceramics. The BR-2 platform (5.8-5.9 m depth) contained less pottery (<20%) and included well-preserved fragments of Early Helladic (EH) jars.</p> <p>The beachrock elevations and <sup>14</sup>C and pottery ages were used to reconstruct a sea level curve and a series of paleogeographic maps of the EH to LH shorelines. The presence of abundant pottery and wood charcoal in the BR-1 beachrock indicates that shipping activity during the LH was focused at the south end of the site in a western harbour basin. This is supported by magnetic gradiometer results, which identified several magnetic anomalies in the western harbour basin. These were investigated by diver search and found to be concentrations of ship ballast stones (mainly andesite) and clay pottery.</p> / Master of Science (MSc)
3

Tect?nica e sedimenta??o neog?nica-quatern?ria na plan?cie liter?nea do Rio Assu, Bacia Potiguar / Neogene - quaternary tectonics and sedimentation in the coastal plain of the Assu River, Potiguar Basin

Barbosa, Maria Emanuella Firmino 28 August 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-12T18:53:10Z No. of bitstreams: 1 MariaEmanuellaFirminoBarbosa_TESE.pdf: 17456528 bytes, checksum: 1ca17d60d4523399fe8138c2a7d13c40 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-13T21:30:21Z (GMT) No. of bitstreams: 1 MariaEmanuellaFirminoBarbosa_TESE.pdf: 17456528 bytes, checksum: 1ca17d60d4523399fe8138c2a7d13c40 (MD5) / Made available in DSpace on 2017-12-13T21:30:21Z (GMT). No. of bitstreams: 1 MariaEmanuellaFirminoBarbosa_TESE.pdf: 17456528 bytes, checksum: 1ca17d60d4523399fe8138c2a7d13c40 (MD5) Previous issue date: 2017-08-28 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Uma pesquisa geomorfol?gica detalhada usando Light Detection and Ranging (LIDAR) foi realizada ao longo da parte ocidental do rio Assu, estado do Rio Grande do Norte, Brasil. O estudo foi complementado por uma s?rie de sondagens com trado, indicadores de foramin?feros bent?nicos de sedimentos, bem como data??o por Optically Stimulated Luminescence (OSL) e por Radiocarbono (C14). Esses dados permitiram reconstruir a evolu??o desta ?rea desde o Pleistoceno tardio at? o presente. O ba?a rasa, que agora est? completamente preenchido formado dentro dos limites da morfologia antecedente desenvolvida desde a ?ltima interglacial. Os principais fatores for?adores respons?veis pelo reposicionamento do litoral, que correu em um ?ngulo de ca. 35% para a costa atual no Pre Holoceno e M?dio Holoceno foram: (1) atividade tect?nica ao longo da linha de falha de Afonso Bezerra, define a estrutura de horst-graben da Serra do Mel, (2) inunda??o r?pida da ba?a do paleovale raso durante a ?ltimo pulso da transgress?o do Holoceno ca. 7500 cal BP e (3) prograda??o r?pida do estu?rio do rio Assu atrav?s da acumula??o de sedimentos costeiros e sedimentos fluviais. / A detailed geomorphological survey using Light Detection and Ranging was carried out along the western part of Assu River, NE, Brazil. The study was complemented by a series of shallow boreholes, sediment benthic foraminifera indicators, as well as radiocarbon and optically stimulated luminescence dating and permitted to reconstruct the evolution of this area from the late Pleistocene until the present. The shallow embayment, which is now completely infilled formed within the limits of antecedent morphology developed since the last interglacial. The main forcing factors responsible for repositioning of the shoreline, which ran at an angle of ca. 35% to the present coast in Early/mid Holocene were: (1) tectonic activity along Afonso Bezerra a strike-slip fault line which defines the horst-graben structure of Mel dome, (2) fast inundation of the shallow paleovalley embayment during the last pulse of Holocene transgression ca. 7500 cal BP, and (3) fast progradation of the Assu estuary through accretion of coastal drift and fluvial sediments.
4

Evaluating the East Java Tsunami Hazard: What Can Newly-Discovered Imbricate Coastal Boulder Accumulations Near Pacitan and at Pantai Papuma, Indonesia Tell Us?

Meservy, William Nile 01 October 2017 (has links)
Our paleotsunami surveys of the southern Java coast led to the discovery of five imbricate coastal boulder fields near Pacitan, Indonesia that may date to the mid-to-late 19th century or prior and two similar fields at Pantai Papuma and Pantai Pasir Putih that were tsunami-emplaced during the 1994 7.9 Mw event in East Java. Estimated ages for the fields near Pacitan are based on historical records and radiocarbon analyses of coral boulders. The largest imbricated boulders in fields near Pacitan and in East Java are similar in size (approximately 3 m^3) and are primarily composed of platy beachrock dislodged from the intertidal platform during one or several unusually powerful wave impactions. Hydrodynamic wave height reconstructions of the accumulations near Pacitan indicate the boulders were likely tsunami rather than storm-wave emplaced, as the size of the storm waves needed to do so is not viable. We evaluate the boulders as an inverse problem, using their reconstructed wave heights and ComMIT tsunami modeling to suggest a minimum 8.4 Mw earthquake necessary to dislodge and emplace the largest boulders near Pacitan assuming they were all deposited during the same tsunami event and that the rupture source was located along the Java Trench south of Pacitan. A combined analysis of historical records of Java earthquakes and plate motion measurements indicates a seismic gap with >25 m of slip deficit along the Java Trench. A 1000-1500 km rupture along the subduction interface of this segment is capable of producing a 9.0-9.3 Mw megathrust earthquake and a giant tsunami. However, evidence for past megathrust earthquake events along the this trench remains elusive. We use epicenter independent tsunami modelling to estimate wave heights and inundation along East Java in the event that the trench were to fully rupture. By translocating ComMIT slip parameters of Japan's 2011 9.1 Mw event along the trench offshore East Java, we demonstrate possible wave heights in excess of 20 m at various locations along its southern coasts. Approximately 300,000-500,000 people in low-lying coastal communities on the southern coasts of East Java could be directly affected. We recommend at-risk communities practice the "20/20/20 principle" of tsunami hazard awareness and evacuation.
5

Porosity and Cement Development In Pleistocene Key Largo Limestone, Key Largo Florida

Cooper, Lorie Debra 05 1900 (has links)
<p> A detailed petrographic study of the Pleistocene Key Largo Limestone Formation, Key Largo, Florida, was undertaken observing three units of varying ages. From oldest to youngest, these are: Q4A (age unknown); Q4B, (180,000 years B.P.), and Q5, (125, 000 years B.P.). Fifty thin sections from four cored wells were point counted. Porosity remained constant for all three units at 28.5% as did total cements at 27.5%. These are still very porous rocks relative to ancient carbonates, which generally show 0-2% porosity. Q5 is diagenetically less mature than Q4B and Q4A, with the persistence of aragonite (which is being leached) and solution-enhanced interparticle porosity. Q5 has been exposed to a vadose environment. Multiple generation cements in Q4B indicate two periods of vadose exposure coincident with known Pleistocene eustatic sea level fluctuations. Moldic porosity is predominant in Q4B. Vague horizons of macroscopic vuggy porosity act as pathways of directed flow for percolating fluids precipitating late stage cements and stains rich in iron. Q4A has been interpreted as a beachrock in part, deposited at pH's greater than 9, resulting in dissolution of quartz grains. Of special interest in Q4A is the probable exploitation of a quartz substrate by endolithic borers. </p> / Thesis / Bachelor of Science (BSc)

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