Advances in geochemical tracing of atmospheric dust in Antarctica

• Main Author: Vanderstraeten, Aubry
• Other Authors: Mattielli, Nadine, Bonneville, Steeve, Debaille, Vinciane, Fripiat, François, Gabrielli, Paolo, Bory, Aloys, Deboudt, Karine
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universite Libre de Bruxelles 2020
• Subjects: Géochimie; Phénomènes atmosphériques; Géologie; Géographie physique; tracing of atmospheric dust; Geochemistry (REE-isotopes); Antarctica -PEA station; chromatography; Antarctic; Sør-Rondane; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/312773; https://dipot.ulb.ac.be/dspace/bitstream/2013/312773/5/ContratDiVanderstraeten.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/312773/4/Thesis_AVD_Difusion_table_des_matieres.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/312773/3/Thesis_AVD_Difusion.pdf

AbstractAtmospheric dust is a major component of the Earth System. The optical properties of dust and their roles in cloud nucleation processes have a major impact on Earth’s radiative budget and hydrological cycle. Dusts also take part in many biogeochemical cycles in surface waters of the oceans and on land through their capacity to supply key micronutrients (e.g. Fe, P) sustaining primary production. The aim of this thesis is to improve the understanding of dust cycle by creating new and innovative methods allowing to trace the source regions of dust and quantify their respective contributions. We developed a chromatographic method to isolate and analyze six isotopic systems (i.e. Pb, Nd, Sr, Zn, Cu, Fe) widely used to trace dust source areas. We optimized a new method for single, low-mass dust samples and, in doing so, we observed that the usual rock reference materials (RM) used to calibrate isotopic analysis were not representative of dust. In fact, there is little to no RM for dust and therefore, we set out to characterize precisely the isotopic signatures of two new dust reference materials, ATD and BCR-723. The latter two are representative of natural-like and urban-like dust that we propose now as new standards for atmospheric dust studies. We also investigated dust deposition, along a 250-km transect from the NE Antarctic coastline to the Princess Elisabeth Station area. Using dust samples collected from Sigma-2 passive samplers or isolated from snow samples, we determined the morphology, size distribution and chemical composition of the dust samples at the particle-scale using an automated Scanning Electron Microscope coupled to Energy Dispersive Spectroscopy (SEM-EDS). More than 5500 particles were analysed and the results showed that the grain-size distribution was <5 μm. We also observe difference in mineralogy at the coast compared to the inland section of our transect: dominance of quartz and aluminosilicates at the coast and of Fe-Mg silicates near the Sør Rondane. Based on this discrepancy, ...