PhD at the University Claude Bernard Lyon 1 (LEHNA-IAPHY team)

PhD in micro and nano-plastics transfers in the vadose zone below infiltration systems: laboratory experiments and modelling

The Laboratory of Ecology of Natural and Anthropized Hydrosystems (LEHNA) invites applications for a 3-year PhD position integrated into the Marie Skłodowska-Curie Doctoral Network “PlasticUnderground” aiming to develop solutions to the emerging plastic pollution crisis in soils and groundwater.

Societal and scientific context

Due to the disturbance of the water cycle with global changes, particularly in urban areas (e.g., depletion of groundwater resources, urban heat island effect, stormwater runoff, and soil artificialization), aquifer recharge practices were developed to restore the natural water cycle in cities. Recharge practices include infiltrating water into specific infiltration systems (IS) or Sustainable Urban Drainage Systems (SUDS). The vadose zone (VZ) underneath IS is then crucial with regard to water fluxes regulation and pollutant filtration. In this context, the fate of pollutants carried by the infiltrating water and their transfer through the vadose zone below IS have been the subject of numerous studies for decades. The acknowledgment of the pollution with micro- and nano-plastic particles (MnP) pushed scientific communities to tackle the issue of MnP fate in the environment. So far, MnP transfers in IS have received little attention, and most studies have investigated MNP concentrations in different environments. Additional research is required to fill in the gaps in knowledge on the physical processes and geochemical mechanisms responsible for their transfer in the environment, notably in the vadose zone. This knowledge is essential for assessing the risk of degradation of groundwater quality by IS.

This study lies within the context of the investigation of MnP transfer in VZ below IS and related risk for the groundwater. Based on laboratory experiments and modeling approaches, we aim to identify the main drivers for MnP transfer and retention in the VZ and their links with the soil hydraulic and transfer properties and the hydrological context. Column experiments will be carried out with model metal-doped plastics under dynamic conditions (steady uniform flow) and for varying flow regimes (entering fluxes), hydric conditions (unsaturated versus saturated conditions), and materials (different types of materials, homogeneous versus layered profiles). Additional experiments (batch experiments and micro-observations) will be deployed to add information on processes at the particle scale. Experimental results will be coupled with a specific modeling approach for identifying the physical processes and geochemical mechanisms responsible for the MnP transfer in the columns and their links with the material hydraulic and transfer properties and the injection mode. In addition, the thesis will provide insight into the dependency of involved mechanisms upon the type of material and the hydrogeological context. The thesis results should provide a modeling framework for predicting MnP transfer in the vadose zone below IS and, thus, a tool for managing these systems.

Job description

The thesis will involve laboratory column experiments to simulate the transfer of MnP in materials encountered below IS. The experimental design will investigate the following contrasting conditions: unsaturated versus saturated conditions (to mimic wetting/drying cycles), injection of several flow rates, and transfer through different materials simulating soils, sediments, or layered systems representative of the IS in the region of Lyon (France). In more detail, materials will be embedded in the columns at a given bulk density in accordance with field measurements. Columns will then be submitted to steady flow and fed with different solutions (tracer and the studied MnPs). Bromide (Br) will be used as a tracer to characterize flow pathways. The MIM model will be used to model Br BTCs

(Breakthrough Curves) to characterize water fractionation into mobile-immobile water fractions and related hydrodynamic parameters. The injections of metal-doped MnP in pulse mode will be carried out to provide both breakthrough curves (BTC) and retention profiles at the end of the column experiment to characterize the elution at the column outlet and the retention in the system. The moment method will provide insight into retention mechanism reversibility and kinetics. The two signals, i.e., BTCs and retention profiles, will be modeled with different hypotheses of sorption (reversible versus irreversible, instantaneous versus kinetically limited sorption, etc.) on the basis of the results of batch experiments (sorption isotherms and kinetics). The resulting framework is expected to provide the identification of physical processes (solute transport) and geochemical mechanisms (sorption), the corresponding equations, and related parameters, thus enabling anyone to model MnP transfer in the vadose zone under both direct and inverse mode.

This position is offered as one of 14 fully funded Ph.D. positions funded by the Marie-Skłodowska-Curie Actions Doctoral Network “PlasticUnderground”. The PlasticUnderground Doctoral Network (DN) is an international, multi-partner, inter-sectoral doctoral research-training network aiming to prepare an international cohort of Doctoral Candidates to develop solutions to the emerging plastic pollution crisis in soils and groundwater. Given the evolving understanding of subsurface soil and groundwater ecosystems as long-term storage pools of micro- and nanoplastics, the interdisciplinary capacity that can support and provide guidance for the management of these systems, as well as the development of adequate technological, social-behavioral, and legislative solutions is urgently needed. This interdisciplinary DN will integrate comprehensive training opportunities in cutting-edge technological innovations and regulatory and behavioral approaches across traditional disciplinary and sectoral boundaries. The consortium comprises universities, research institutions, and companies in the UK, France, Spain, Serbia, Italy, Switzerland, Cyprus, and Germany.

Profile of the candidate:

1. 1-  Master’s degree in environmental science, soil physics, contaminant hydrology, modeling

2. 2-  Experience in solute transfer, modeling, and micro-nano-plastics would be an asset.

3. 3-  The ability for independent and organized work is essential

4. 4-  Skills for teamworking with integration into a team with diverse research backgrounds and

   collaboration within the PlasticsUnderground DN and the host laboratory.

5. 5-  The working language is English, and advanced communication skills in English (oral and

   written) are expected.

The selected candidate can be of any nationality but must comply with the mobility rules of the PlasticsUnderground DN. At the time of selection by the host organization, candidates must not have resided or carried out their main activity (work, studies, etc.) in the country of their host organization for more than 12 months in the three years immediately prior to their recruitment.

Work Location

This Ph.D. position will be hosted by the LEHNA-IAPHY team in ENTPE (National School of State Public Works); The Ph. D. will be supervised by a supervision team involving Laurent Lassabatere (Director), Laurence Volatier (co-supervisor), and Brice Mourier (co-supervisor). The supervision team has all the skills required to supervise and train the Ph. D. on experiments and modeling. The hosting laboratory will provide all the means required to conduct the work. Our research group focuses on the functioning of aquatic ecosystems. We have been interested in studying microplastics' fate, transport, and impacts in aquatic ecosystems for five years. We are working in coordination with the Metropole of Lyon on managed aquifer recharge systems offering all the tools required to quantify and model pollutant transfer at the laboratory scale (column experiments and batch experiments).

The position is fully funded for three years by the PlasticsUnderground DN. Ph.D. salaries will be in accordance with European standards. In addition to the facilities in the LEHNA lab, the PlasticsUnderground DN will provide ample opportunities for international and inter-sectoral secondments, International Joint Experiments, and Advance Training Courses (ATCs), among other activities. Consequently, the candidate is expected to travel internationally during the appointment.

Selection process
Please send your application to Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser., Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser., and

Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser. until May 07, 2023. The application should include: 1) CV

2. 2)  Copies of original diploma of bachelor’s and master’s degree

3. 3)  Letter of motivation

4. 4)  The names and contact details of two potential referees.