This Ph.D. dissertation integrates stable isotope and trace element geochemistry in modern and fossil gastropod shells to study low-latitude marine paleoenvironments. First, stable isotopes (delta18O and delta13C) and Sr/Ca ratios are used to examine low-latitude temperature and salinity variations recorded in Plio-Pleistocene (3.5-1.6 Ma) fossils from western Florida during periods of high-latitude warming and "global" cooling. The middle Pliocene Pinecrest Beds (Units 7 and 4) and the overlaying Plio-Pleistocene Caloosahatchee Formation generate significantly different delta18O-derived paleotemperatures but identical Sr/Ca ratios. High delta18O values, together with low delta13C values and brackish fauna, indicate that Unit 4 was deposited in a lagoonal environment similar to modern Florida Bay. In contrast, relatively low delta18O and high delta13C values in Unit 7 and Caloosahatchee Formation represent deposition in an open-marine environment. The observed Unit 7 and Caloosahatchee paleotemperatures are inconsistent with middle Pliocene warming event, but consistent with the Plio-Pleistocene cooling trend. To quantify modern upwelling and freshening signals and contrast these signals between the tropical eastern Pacific (TEP) and southwestern Caribbean (SWC), methodologies are developed for reconstructing seasonal upwelling and freshening patterns from modern tropical gastropod shells from Panama using: 1) paired oxygen and carbon isotopic profiles and delta18O-delta13C (delta-delta) correlations, and 2) deviation from baseline delta18O values that represent conditions free of seasonal upwelling or freshening influences. Shell delta18O values normalized to the baseline faithfully record modern conditions of little or no upwelling in SWC and Gulf of Chiriqui, and strong upwelling in the Gulf of Panama, as well as strong freshwater input in most areas. The baseline and delta-delta methods are applied to identify and quantify changes in upwelling and freshening in the Neogene TEP and SWC seawaters associated with the final closure of Central American Isthmus. The records reveal significant upwelling in late Miocene SWC and mid Pliocene TEP waters, strong freshening in SWC waters from 5.7-2.2 Ma, and minimal seasonal upwelling and/or freshening variations in Plio-Pleistocene SWC waters. The reconstructed paleotemperatures agree with the global cooling trend through the late Miocene, but lack evidence for middle Pliocene warming or late Neogene global cooling.

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-05-16T23:42:54Z No. of bitstreams: 1 RaniereBL_TESE.pdf: 1911873 bytes, checksum: 9491f9b0de354e3c0d41ccb579f502f1 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-05-17T11:03:52Z (GMT) No. of bitstreams: 1 RaniereBL_TESE.pdf: 1911873 bytes, checksum: 9491f9b0de354e3c0d41ccb579f502f1 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-05-17T11:04:10Z (GMT) No. of bitstreams: 1 RaniereBL_TESE.pdf: 1911873 bytes, checksum: 9491f9b0de354e3c0d41ccb579f502f1 (MD5) / Made available in DSpace on 2017-05-17T11:04:28Z (GMT). No. of bitstreams: 1 RaniereBL_TESE.pdf: 1911873 bytes, checksum: 9491f9b0de354e3c0d41ccb579f502f1 (MD5) Previous issue date: 2016-08-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use of treated sewage effluents is a way of avoids environmental pollution and also a viable choice to increase water availability in arid and semiarid regions. However, it is necessary to understand characteristics of the end product to avoid undesirable effects and, to allow its use as material for irrigation and plant fertilization, among others. As option to agricultural produce, sorghum plants were growth in open-field under irrigation with treated domestic wastewater from wastewater treatment plant located in Milagres Settlement Project, Apodi state, Brazil. The experiment was carried out using the experimental design in completely randomized blocks, with three replications. Treatments followed a factorial scheme 3 x 3, with three water source (well water - control, treated sewage effluent and, mixture of 50% water well + 50% treated sewage effluent) and, three sorghum cultivars (IPA 2502, BRS 506 and BRS Ponta Negra). Result showed that BRS Ponta Negra cultivar responded positively to the increase of wastewater in relationship the variables leaf area, leaf number, dry matter and green mass weight, than the other treatments. Agricultural use of treated domestic wastewater and mixtures of 50% well water + 50% treated domestic wastewater were water sources that resulted in higher sorghum yields. The vegetative and productive increase of sorghum plants BRS 506, IPA 2502 and Ponta Negra was positively influenced by the waters: sewage, mixture and supply successively used in the fertirrigation and the waters sewage and mixture, resulted in greater production of biomass: briquettes production, Production of ethanol and calorific value / O uso de esgoto doméstico tratado é uma forma efetiva de controle da poluição ambiental e uma opção viável para aumentar a disponibilidade hídrica nas regiões áridas e semiáridas. No entanto, é necessário compreender as características do produto final para evitar efeitos indesejáveis e permitir seu uso como material para a fertilização e irrigação das plantas, entre outros. Como opção de produção agrícola, plantas de sorgo forrageiro foram cultivadas em campo aberto e irrigadas com esgoto doméstico tratado da estação de tratamento de águas residuais, localizado no projeto de Assentamento de Milagres, Apodi, RN. O experimento foi conduzido em delineamento experimental de blocos casualizados, com modelo em parcelas subdivididas, sendo três fontes hídricas referente às parcelas (Água de poço - controle, água de esgoto doméstico tratado e a mistura de 50% água de poço + 50% esgoto doméstico tratado) e três cultivares de sorgo ( IPA 2502, BRS 506 e BRS Ponta Negra). Os resultados mostram que a cultivar BRS Ponta Negra respondeu positivamente ao incremento de águas residuárias nas variáveis áreas foliar, número de folhas, massa de matéria seca e produção de massa verde quando comparadas com as demais. O uso agrícola do esgoto doméstico tratado e a misturas de 50% água de poço + 50% esgoto doméstico tratado foi a fonte hídrica que resultara na maior produção de sorgo. O aumento vegetativo e produtivo das plantas de sorgos BRS 506, IPA 2502 e Ponta Negra foi influenciado positivamente pelas águas: esgoto, mistura e abastecimento sucessivamente usado na fertirrigação e As águas esgoto e mistura, resultou em maior produção de biomassa: produção de briquetes, produção de etanol e poder calorífico / 2017-05-16