Tracing of atmospheric and anthropic nanoparticules in urban area with natural and passive sensor

For the first time, this thesis project proposes to carry out a spatial study and trace urban atmospheric nanoparticles (NPs) or ultrafine particles (PUFs) by combining innovative and complementary analytical techniques: magnetic analyses, single-particle ICPMS, microscopic and geochemical analyses. In addition to the “classic” microphysical and geochemical characterization techniques (MET-EDX, ICP-MS), innovative techniques (sp-ICP-ToF-MS) are being developed and applied to the problem of NPs, as they can help overcome the analytical barriers that have so far limited their systematic detection and characterization. The study focuses on the Paris conurbation, the only megalopolis in Western Europe (10 million inhabitants), and as such the results of the study will have a global impact. Tree bark is regarded as a passive sensor, enabling PUFs to be collected in the vicinity of major roads, as well as in more remote areas such as parks. Several bark digestion methods are compared in order to optimize the extraction of NPs into solution, prior to their analysis by spICPMS. Microscopic analyses combined with spICPMS (chemical compositions of PUFs, including Fe, Cu, Sn, Sb, Zn, Cd, Co, Cr, Mn, Pb and Al) provide a multi-parameter signature of PUFs with a precision unmatched today. A study of the sources of these PUFs is also being undertaken, in order to determine the chemical signature of the various sources and to distinguish, at the scale of the agglomeration, anthropogenic from geogenic NPs.