Themes: Geological Sciences, Earth, Universe
location: Research Laboratory for Radionuclide Transfer in Terrestrial Ecosystems (LR2T) - Cadarache (13)
Masters degree or engineer degree in environmental physics, statistics and modeling. Autonomy, rigor (especially at the experimental level), ability to work in a team, motivation, fluency in English.
Age limit: 26 years old unless otherwise stated.
Soil heterogeneity strongly influences contaminant sorption in soils. Firstly because the different soil constituants do not have the same reactivity (e.g. calcareous soil vs mineralogic clays). Secondly because their spatial arrangement in a real soil can create particular conditions of reactive transport, like for instance a microporosity with strong reactivity but poorly accessible to mobile water. In general, laboratory data on sorption concern the 0-2 mm size fraction. The rest of the soil is excluded from experimental studies, even if it can represent a significant mass of the soil (e.g. the 2-5 mm fraction). Using sorption parameters concerning the 0-2 mm fraction to describe the whole soil may introduce errors in the reactivity of the real porous medium. In this PhD project, we propose to study the influence of the granulometric classes on sorption properties. This work will imply experiments in the laboratory with the 0-2mm and 2-5 mm fractions of soils: sorption isotherms, breakthrough experiments in small soil columns and dynamics of contaminant profiles in a heterogeneous media (mixture of 0-2 and 2-5 mm size fractions). The experiment with heterogenous porous media will be done in decimetric soil columns monitored with in situ gamma-ray spectrometry. In this project, the object of study will be specifically 137Cs and contrasted soils already studied at SRTE/LR2T: candidates soils are a sandy soil (EDF site), a more clayey soil (Hercqueville) and an andosoil (Kawamata, Fukushima prefecture).