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Master's Dissertation
DOI
10.11606/D.44.1995.tde-11092015-093226
Document
Author
Full name
Cleyde Correa Roncaratti
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1995
Supervisor
Committee
Levi, Franco (President)
Hypólito, Raphael
Mesquita, Carlos Henrique de
Title in Portuguese
Modelo global do ciclo biogeoquímico do carbono-enxofre
Keywords in Portuguese
Biogeoquímica
Abstract in Portuguese
Os dois ciclos mais importantes nas reações de oxi-redução, no ambiente de superfície, são o do carbono e o do enxofre que fazem parte de um sistema maior que compreende a atmosfera, biosfera e litosfera sedimentar. Levando isso em conta, partimos de um modelo de simulação numérica do ciclo biogeoquímico global, para investigar o papel do sistema carbono-oxigênio-enxofre. A modelagem se baseia em estudos nos quais o ciclo do carbono é conjugado com o ciclo do enxofre, elaborada a partir dos principais mecanismos de oxi-redução envolvidos nos ciclos biogeoquímicos das rochas sedimentares e no registro isotópico do sulfato e carbonato marinho, durante o Fanerozóico. A descrição numérica que compõe a estrutura do modelo se apresenta sob a forma de um sistema de Equações Diferenciadas Ordinárias, empregando uma técnica de modelagem em Fortran que descreve as influências mútuas entre os diversos parâmetros geoquímicos envolvidos. Para o intervalo de tempo considerado, os resultados se apresentam qualitativamente válidos, embora contraditórios quando se observam os teores de oxigênio atmosférico estimados. Hipóteses mais elaboradas associadas a metodologias mais adequadas permitirão estender este estudo, possibilitando previsões mais precisas e abrangentes que conciliem de forma mais satisfatória os aspectos ambientais, tanto a nível local como regional e global.
Title in English
Not available.
Keywords in English
Not available.
Abstract in English
Carbon and sulfur cycles comprise a pair of cycles of outstanding importance when the redox processes of the atmosphere, biosphere and the sedimentary lithosphere are considered within an integrated whole. These considerations triggered in this work the development of numeric models capable of investigating the global biogeochemical within the carbon-oxigen-sulfur system. Modeling is based on studies the carbon is considered as coupled with the sulfur cycle, in terms of the main redox mechanisms involved in the biogeochemical cycles of sedimentary rocks and in the isotopic record of marine sulfates and carbonates, during the Phanerozoic. The model structure comprises a numerical description presented as a system of Ordinary Differential Equations, using a Fortran modeling technique that describes the mutual influences among the various geochemical variables involved. Along the investigated time interval, results are apparently coherent, although somewhat contradictory as far as the estimated oxygen contents are concerned. More elaborated hypotheses, associated to more adequate methodologies will allow us to extend this study in order to suggest predictions that will be both more precise and span wider intervals, including environmental aspects at the local, regional and global scales.
 
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Publishing Date
2015-09-16
 
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