Composició, origen i transport de matèria orgànica en marges continentals i conques de la mar Mediterrània = Composition, origin and transport of organic matter in continental margins and basins of the Mediterranean Sea
One of the grand challenges in marine biogeochemistry is to improve our understanding on the temporal (seasonal and multi-annual) and spatial (regional and global) variability of ocean uptake of CO2, and the physical and biological processes that regulate this process. In this context, the study of...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/400707 |
| Acceso en línea: | http://hdl.handle.net/10803/400707 |
| Access Level: | acceso abierto |
| Palabra clave: | Geologia submarina Geología submarina Submarine geology Fons marins Fondo del mar Ocean bottom Mediterrània (Mar) Mediterráneo Mediterranean Sea Geoquímica orgànica Geoquímica orgánica Organic geochemistry Ciències Experimentals i Matemàtiques 55 |
| Sumario: | One of the grand challenges in marine biogeochemistry is to improve our understanding on the temporal (seasonal and multi-annual) and spatial (regional and global) variability of ocean uptake of CO2, and the physical and biological processes that regulate this process. In this context, the study of the environmental conditions that control organic carbon (OC) fixation, OC sinking, OC burial, and thus OC sequestration becomes critical to better understand feedbacks between the atmospheric CO2 concentration and the oceans, and how they play a key role in climate regulation and climate change. This is of special importance in oligotrophic waters, which roughly cover 75% of the ocean’s surface and contribute over 30% of the global marine carbon fixation. In this PhD Thesis several fundamental questions have been studied such as ‘Which environmental forcings are involved in OC fixation and sinking in an oligotrophic and semi- enclosed environment such as the Mediterranean Sea?’, and ‘How and where does OC accumulate, and how its origin affects its preservation and burial in the deep sediments?’. The combined analysis of continental shelf, slope, and deep basin surface sediments and particle fluxes, together with the study of the meteorological, hydrological and oceanographic settings at each environment, have revealed that atmosphere-driven oceanographic events play a major role in the carbon cycle in the Mediterranean Sea. Thus, coastal storms with strong winds, high waves and intensified currents have been proved to be efficient at transporting OC from shallow to deeper environments, with submarine canyons acting as a preferential conduit. This transport to deep sedimentary environments is mainly controlled by the hydrodynamic sorting and differential deposition of particles with different grain sizes, being the finer those with the highest loadings of OC and those that can be transported long distances. In addition, open sea storms with cold and dry northerly winds trigger convective mixing, nutrient uplifting and episodic events of increased carbon export to abyssal areas. Moreover, in these cases, the arrival of additional nutrients due to extraordinary atmospheric deposition of volcanic ash can cause the intensification of export of fresh phytodetritus. |
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