CIFRE PhD position - Fate of PFAS in agricultural soils.

CIFRE: research partnership between academic and socio-economic spheres.
Host company: Veolia Agriculture
Host laboratories at INRAE :
– Laboratoire de Biotechnologie de l'Environnement (LBE), 11100 Narbonne
– Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes, (EMMAH), 84000 Avignon).
 

Context

Per- and polyfluoroalkyl substances (PFAS) are xenobiotics that have been used for several decades in a wide range of applications. Some are persistent in the environment and/or harmful to the health of living organisms. PFAS enter agroecosystems through certain pesticides, atmospheric deposition, irrigation with contaminated water, and the recycling of organic waste products (OWP). In soils, PFAS can be taken up by crops or soil organisms, migrate into groundwater, and thus pose a threat to water resources, crops, and consumer health. This thesis is part of the ANR-funded FluorAgro project (2026-2030) aimed at identifying sources of PFAS in agroecosystems, predicting their fate in soil, and studying their bioavailability. The thesis will contribute to improving predictions of PFAS fate in soil.
Objective: Study and model the fate of PFAS in the Organic-Waste–Soil–Water continuum. This objective is broken down into three research questions, which will be addressed using appropriate tools and methods:
 

• Do organic waste treatment processes (e.g., anaerobic digestion, composting) affect the distribution of PFAS across different organic fractions? Do they lead to the degradation of perfluoroalkyl acid precursors? What will be the consequences for PFAS mobility in soils after application?
  → Sampling of organic waste products from long-term field trials, physical and biochemical fractionation of organic matter, quantification of PFAS in each fraction
  ● Two mechanisms that have received little attention may control the fate of PFAS in soil: preferential transport in macropores and transport in the colloidal phase, which facilitates the mobility of pollutants that would otherwise be poorly mobile. Will the introduction of colloidal organic matter via the OWP exacerbate this transport mechanism for long-chain PFAS? Will diffusion from the soil matrix to preferential flow paths be the process that limits the leaching of shorter-chain PFAS?
  → Leaching experiments on soil column extracted from long-term field trials. Measurement of drainage hydrographs and water tracer elution curves. Quantification of the fraction of colloid-bound PFAS in the leachates, colloid characterization.
• To predict the fate of PFAS in soil, a numerical model will be developed during the FluorAgro project. The PhD student will parametrize this model from the column experiments and will test it by comparing its predictions with PFAS concentration measured in lysimeters located in the long-term field trials.
  → The modeling work will be carried out in the Vsoil platform developed by INRAE at EMMAH Avignon.
   

Training and skills

The candidates must hold a Master degree or an engineer diploma and have skills in soil physics or in modeling, ideally in the field of mass transfer (water, solutes, colloidal particles) in porous media. Previous experience with contaminant fate in soils would be a plus. An interest for experimental laboratory work is necessary.

Duration and location

36-months fixed term contract, starting ideally in September or October 2026. The candidate will spend 9 months at LBE, 20 months at EMMAH and 7 months at Veolia.