Moreno Rivadeneira C. I. (2011). Natural variability of the atmospheric composition and anthropogenic influence in Patagonia : contribution to the understanding of transport pathways along the Equator - Mid latitudes - Pole transect.
Grenoble (FRA) ; Montpellier : Université de Grenoble ; IRD, 213 p. multigr. Th. : Sci. de la Terre, de l'Univers et de l'Environ., Université de Grenoble. 2011/01/19.
Titre du document
Natural variability of the atmospheric composition and anthropogenic influence in Patagonia : contribution to the understanding of transport pathways along the Equator - Mid latitudes - Pole transect
Année de publication
2011
Type de document
Diplôme
Auteurs
Moreno Rivadeneira C. I.
Source
Grenoble (FRA) ; Montpellier : Université de Grenoble ; IRD, 2011,
213 p. multigr.
Diplôme
Th. : Sci. de la Terre, de l'Univers et de l'Environ., Université de Grenoble. 2011/01/19.
Although tropical and subtropical South America play an important role in atmospheric global and hemispheric chemistry due to the coexistence of big reservoirs with large-scale atmospheric patterns, exchanges between tropics and higher latitudes have remained poorly documented. During the last few decades, the study of past climate and atmospheric composition has benefited greatly by information provided by ice core analysis. In the Southern Hemisphere, a large amount of data is now available from polar ice cores and more recently from ice cores recovered in the Andes. Despite a few studies on climate reconstruction, there is a lack of information on past atmospheric composition in Southern mid-latitudes, in terms of both natural variability and anthropogenic impact. This work is based on the analysis of a 122 m ice core extracted from a high altitude site in the Northern Patagonian Icefield (Monte San Valentin 46°35' W, summit at 4032 m.a.s.l., drilling plateau at 3723 m.a.s.l.). Besides high-resolution measurements of mineral and organic ions, a study of the precipitation events likely to influence the site was conducted in order to provide a basis for the interpretation of the ice archive. The selected site registers precipitation events of marine and continental origin. We have demonstrated that marine primary and biogenic contributions are not synchronous and they are very likely underrepresented along the ice archive due to the effect of accumulation processes. Contrary to sea salt, a significant part of marine biogenic aerosol is associated with a complex trends and major events involving combustion processes, urban pollution, volcanic and soil emissions. This set of mixed sources is responsible for almost half of the total sulface input. This important and ubiquitous sulfate concentration is related to that of nitrate and chloride and its understanding in terms of sources and transport needs further research. A comparison of our records with documented volcanic eruptions and Patagonian settlement periods allowed us to propose a few dating horizons, although an accurate dating of the entire core has not been possible so far. Background trends of continental species do not show any trend that can be clearly associated with and anthropogenic influence, except for ammonium, which increases likely in response to fertilizer consumption after ca. 1960.
