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Reference : UMR5563-EVASCH-001
Workplace : TOULOUSE
Date of publication : Friday, October 8, 2021
Type of Contract : FTC Scientist
Contract Period : 12 months
Expected date of employment : 1 February 2022
Proportion of work : Full time
Remuneration : -between 2660 and 3785 € per month depending on experience
Desired level of education : PhD
Experience required : 1 to 4 years
The proposed post-doctorate is part of the DiagnOSE project funded since March 2021 by the Occitanie region. This project focuses on the environmental situation in the Orbiel valley, and in particular in the heart of the former mining district of Salsigne in the Aude. This mine has long been known as the largest gold mine in Europe and the largest arsenic mine in the world. However, the exploitation of the deposits led to the dispersion, in various chemical forms and often present in small particles or in a dissolved phase, of the elements exploited for years, or even centuries, over large territories. This dispersion has thus reached different compartments, such as surface and underground waters, the atmosphere, soils, sediments, the biosphere, etc.
Indeed, the dramatic flood of 14-15 October 2018, which cost the lives of 15 people, has also revived fears linked to this transport of contaminants. The DiagnOSe project therefore aims to provide answers to the population and decision-makers by establishing a global environmental and societal diagnosis of the Orbiel valley based on a multi- and interdisciplinary approach and without any preconceived ideas.
In this general context, the objective of this post-doctorate is to actively participate in the successful completion of batch 2 of the project "Monitoring the chemical composition of the atmosphere", for which everything remains to be done.
The main task will be to assess the air quality from the upstream Orbiel area (Miraval-Cabardès) to Conques-sur-Orbiel.
Contaminated surfaces, especially when they are devoid of vegetation, can be sources of contaminants (metals, metalloids, etc.) as a result of wind erosion (removal of particles). This action allows a large quantity of soil particles to be resuspended in the atmospheric reservoir. These terrigenous particles can be of very different granulometric sizes (a few micrometers to several tens of micrometers).
In addition to this specific source, there are other atmospheric dusts of anthropogenic or natural origin whose diameters can range from a few tens of nanometres to several micrometres (Calvo et al., 2008). The finest particles (PM1, PM2.5, with diameters of less than 1 and 2.5 µm respectively) are those that pose the greatest public health problems due to their ability to penetrate the pulmonary alveoli (Goix, 2012). These different aerosol sources have specific chemical signatures that evolve during their transport in the atmosphere. It is then possible to see the evolution of the degrees of oxidation of certain trace elements (terrigenous source, mining waste source) in contact with organic compounds (from combustion processes or emitted by vegetation depending on the season). Knowing the pulmonary bioaccessibility and the oxidising potential of the atmospheric dusts sampled will also make it possible to target the more or less inflammatory nature of the inhalable particles and is therefore of great interest to health, which will enable us to better assess the health risks generated.
Finally, biomonitoring of air quality by epiphytic plants and the study of the transfer of particles from the "air" compartment to the vegetation by dry and wet deposition will provide better knowledge of the transfer dynamics of these pollutants and their fate within the critical zone.
- The post-doctoral fellow recruited will be responsible for deploying all the equipment on site and ensuring its monitoring.
- He/she will coordinate all the measurements and participate in all the experiments carried out by the project partners.
- He/she will coordinate the experiments with those in charge of the DiagnOSE project's atmosphere package.
- He/she will also be responsible for synthesising all the analyses carried out by the partners in a database and will process the data on the missions directly related to the tasks listed in this work package.
- Finally, he/she will be able to propose an evaluation of the health risks linked to the inhalation of particles contaminated with As and other elements.
- French-native person required for interaction with the population and local communities
- Skills in atmospheric chemistry, geochemistry, isotopes, health risk assessment
- Autonomy, writing and communication skills
The two laboratories leading this study of air quality in the Orbiel valley are very complementary: the Aerology Laboratory (LAERO) brings its expertise in understanding the microphysical and chemical evolution of aerosols within the atmosphere reservoir from their source of emission to their deposition zone. The Geosciences Environment Toulouse (GET) laboratory brings its expertise in the geochemistry of trace elements, the study of their transfer within the various reservoirs (soil, atmosphere, vegetation) and the use of epiphytic plants as bioindicators of atmospheric chemical composition.
In addition to LAERO and GET, other partners will be involved in order to ensure that the planned experiments are carried out correctly: the HSM laboratory will contribute its expertise in the use of isotopic tracers, and the LCA laboratory will contribute its skills in the study of reactivity at interfaces (solid/liquid/gas). The assessments of the bioaccessibility of inorganic contaminants and the health risks will be carried out in partnership with (i) the Institut des Géosciences de l'Environnement (IGE) in Grenoble for the pulmonary bioaccessibility of trace elements and the evaluation of the oxidising potential of atmospheric particles; and (ii) the PEIRENE laboratory, at the University of Limoges, for the mineralogical characterisation of atmospheric particles.
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