Chemical properties of continental aerosol transported over the Southern Ocean : Patagonian and Namibian sources

• Main Author: Qu, Zihan
• Other Authors: Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris VI, Emilie Journet, Rémi Losno
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2016
• Subjects: Atmospheric concentration; Micronutrient; Mineral dust; Solubilité; Composition élémentaire; Concentration atmosphérique; Océan Austral; Patagonie; Aérosol minéral; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Austral; Patagonia; Southern Ocean; South Atlantic Ocean
• Online Access: https://tel.archives-ouvertes.fr/tel-01349197; https://tel.archives-ouvertes.fr/tel-01349197/document; https://tel.archives-ouvertes.fr/tel-01349197/file/2016PA066002o.pdf

Mineral dust is considered to be an important supplier of micronutrient for the Southern Ocean where the primary production is limited by insufficient supply of micronutrients. Patagonia (South America) and Namibia (Southern Africa) are two main dust sources for the South Atlantic section of the Southern Ocean. Emission inventories of bioavailable micronutrients from these two regions regulate the final biological impact on marine ecosystem in the South Atlantic Ocean. This thesis is mainly focused on the investigation of 1) the atmospheric dust concentration and its temporal pattern in Patagonia, 2) the spatial heterogeneity of dust elemental composition in Patagonia and Namibia, and 3) the pH dependence of elemental solubility in Patagonian and Namibian dust. These three aspects are the key issues to model the emission inventories of bioavailable micronutrients from dust sources. Dust concentration measurements were conducted in Patagonia-Atlantic Coast and revealed a seasonal pattern of dust concentration with lower dust level in winter than the other three seasons. Meteorological records suggest that this seasonal pattern is associated with the variation of soil moisture in source areas rather than the recurrently high wind speed. Dust samples were generated from Patagonian and Namibian soils to investigate the elemental composition and the elemental solubility of source dust. Dust elemental composition differs to different degrees from their parents soils, particularly in Namibia due to the dilution effect of quartz in soil. Spatial variability of dust elemental composition was observed at both continental scale and regional scale in Patagonia and Namibia. Variations in Ca and Mg content are the main reasons for the spatial heterogeneity of dust elemental composition. Elemental solubility of Patagonian and Namibian dust increased with acidity of leaching solution. More soluble elements namely Ca, K, Mg, Mn, Sr and Ba showed much higher solubility in calcium-rich dust due to the presence of carbonate. The ...