Ifsttar PhD subject

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Title : Microplastic in the land-to-sea continium: what about sediments from the Loire River?

Main host Laboratory - Referent Advisor GERS - EE  -  GASPERI Johnny      tél. : +33 240845882

Director of the main host Laboratory PEYNEAU Pierre-Emmanuel  -

PhD Speciality Sciences et Techniques de l'Environnement

Axis of the performance contract 3 - COP2017 - Planning and protecting regions

Main location Nantes

Doctoral affiliation UNIVERSITE JEAN MONNET SAINT-ETIENNE

PhD school

Planned PhD supervisor   -    -

Planned financing Contrat doctoral  - Ifsttar

Abstract

1. Contexte
Pollution by plastic debris is a high-profile and growing issue. From a scientific point of view, it focuses on microplastics (MP, size between 1 µm and 5 mm) and mobilises a large number of players at all levels (scientific community, governmental or local authorities, associations, etc.). At the legislative level, the European framework directive "strategy for the marine environment" (DCSMM) clearly targets this pollution with the implementation of actions to reduce and monitor MP in the environment.

Studies on MP in continental environments has only recently begun compared to the marine environment, whereas rivers are the main suppliers of MP to the ocean. A state of the art study of the contamination of continental hydrosystems shows that their sediments are important storage areas for MP, but that they remain a poorly studied and underestimated compartment (Dris et al., 2018). In the vast majority of studies, these sediments are sampled without questioning the hydro-sedimentary processes affecting MP levels and their distribution on different space and time scales (Dekiff et al., 2014; Mani et al., 2018). However, this consideration is crucial to enable both a correct assessment of contamination levels and a comparison of flows on different spatial and temporal scales. The distribution ofMP, particles subject to the same conditions of suspension and deposition as sediment on a catchment scale, depends strongly on the hydro-sedimentary processes involved but also on the intrinsic properties of MP.

This proposal for doctoral work is part of the Plasti-nium project (2021-2025) - Plastic Debris in the Man-Earth-Sea continuum - which aims to study plastic pollution from the city to the sea and to create a transverse and interdisciplinary dynamic on this topic within the Pays de la Loire Region. This project is co-financed by the Pays de la Loire Region and Nantes Métropole, territories that are particularly sensitive to the issue of plastic pollution. The Pays de la Loire region, as part of the "marine ambition" strategy for 2018, is specifically targeting plastic pollution, and points out that very concrete initiatives to reduce it are already operational or are about to be implemented. Nantes Métropole, a territory recognised as a "Zero waste, zero waste" area, also supports experimental, innovative initiatives contributing to a zero waste area. Evaluating the implementation of these actions, whatever their form - from awareness-raising to integrated and concerted management at the level of a territory - is a major challenge.

2. Scientific objectives
This thesis work aims to combine a sedimentological and geochemical approach to PM analysis at the scale of a watershed. In this context, the objectives of this work will be, on the one hand, to analyse the microplastic contents of Loire sediments, whether they have been sampled upstream of the Loire basin or downstream in the estuary zone. On the other hand, they will aim to relate sediment contamination in MP (content, size, chemical nature) to the properties of the sediments. One of the original features of the project lies in the use of complementary analytical techniques for the physico-chemical characterisation of MP by using both spectroscopic methods coupled with infrared spectroscopy (µ-IRTF) and chromatographic methods after pyrolysis and mass detection (Pyr-GC-MS). This analytical combination will provide a wealth of quantitative and qualitative information on PM (concentration vs. number of particles, size distribution, chemical composition) for particles up to a minimum size of 25 µm. Thanks to this identification of the coupling nature of PM/nature of sediments, based on hydro-sedimentary processes, it should be possible to identify the storage areas for these particular sediments. It would thus be possible to identify accumulation zones of MP whose sources are considered diffuse.

Dekiff, J.H., Remy, D., Klasmeier, J., Fries, E., 2014. Occurrence and spatial distribution of microplastics in sediments from Norderney. Environmental Pollution 186, 248–256. https://doi.org/10.1016/j.envpol.2013.11.019
Dris, R., Gasperi, J., Tassin, B., 2018. Sources and Fate of Microplastics in Urban Areas. A Focus on Paris Megacity. Freshwater Microplastics 69, 10–1007.
Mani, T., Lorenz, C., Gerdts, G., Burkhardt-Holm, P., 2018. High Concentrations of Microplastics in the Bed Sediments of the Rhine River. Presented at the Micro20181, Lanzarote.

Keywords : Microplastics, sédiments, Infra-red, Loire, Land-to-sea continium

Main host Laboratory - Referent Advisor	GERS - EE - GASPERI Johnny tél. : +33 240845882
Director of the main host Laboratory	PEYNEAU Pierre-Emmanuel -
PhD Speciality	Sciences et Techniques de l'Environnement
Axis of the performance contract	3 - COP2017 - Planning and protecting regions
Main location	Nantes
Doctoral affiliation	UNIVERSITE JEAN MONNET SAINT-ETIENNE
PhD school
Planned PhD supervisor	- -
Planned financing	Contrat doctoral - Ifsttar
Abstract 1. Contexte Pollution by plastic debris is a high-profile and growing issue. From a scientific point of view, it focuses on microplastics (MP, size between 1 µm and 5 mm) and mobilises a large number of players at all levels (scientific community, governmental or local authorities, associations, etc.). At the legislative level, the European framework directive "strategy for the marine environment" (DCSMM) clearly targets this pollution with the implementation of actions to reduce and monitor MP in the environment. Studies on MP in continental environments has only recently begun compared to the marine environment, whereas rivers are the main suppliers of MP to the ocean. A state of the art study of the contamination of continental hydrosystems shows that their sediments are important storage areas for MP, but that they remain a poorly studied and underestimated compartment (Dris et al., 2018). In the vast majority of studies, these sediments are sampled without questioning the hydro-sedimentary processes affecting MP levels and their distribution on different space and time scales (Dekiff et al., 2014; Mani et al., 2018). However, this consideration is crucial to enable both a correct assessment of contamination levels and a comparison of flows on different spatial and temporal scales. The distribution ofMP, particles subject to the same conditions of suspension and deposition as sediment on a catchment scale, depends strongly on the hydro-sedimentary processes involved but also on the intrinsic properties of MP. This proposal for doctoral work is part of the Plasti-nium project (2021-2025) - Plastic Debris in the Man-Earth-Sea continuum - which aims to study plastic pollution from the city to the sea and to create a transverse and interdisciplinary dynamic on this topic within the Pays de la Loire Region. This project is co-financed by the Pays de la Loire Region and Nantes Métropole, territories that are particularly sensitive to the issue of plastic pollution. The Pays de la Loire region, as part of the "marine ambition" strategy for 2018, is specifically targeting plastic pollution, and points out that very concrete initiatives to reduce it are already operational or are about to be implemented. Nantes Métropole, a territory recognised as a "Zero waste, zero waste" area, also supports experimental, innovative initiatives contributing to a zero waste area. Evaluating the implementation of these actions, whatever their form - from awareness-raising to integrated and concerted management at the level of a territory - is a major challenge. 2. Scientific objectives This thesis work aims to combine a sedimentological and geochemical approach to PM analysis at the scale of a watershed. In this context, the objectives of this work will be, on the one hand, to analyse the microplastic contents of Loire sediments, whether they have been sampled upstream of the Loire basin or downstream in the estuary zone. On the other hand, they will aim to relate sediment contamination in MP (content, size, chemical nature) to the properties of the sediments. One of the original features of the project lies in the use of complementary analytical techniques for the physico-chemical characterisation of MP by using both spectroscopic methods coupled with infrared spectroscopy (µ-IRTF) and chromatographic methods after pyrolysis and mass detection (Pyr-GC-MS). This analytical combination will provide a wealth of quantitative and qualitative information on PM (concentration vs. number of particles, size distribution, chemical composition) for particles up to a minimum size of 25 µm. Thanks to this identification of the coupling nature of PM/nature of sediments, based on hydro-sedimentary processes, it should be possible to identify the storage areas for these particular sediments. It would thus be possible to identify accumulation zones of MP whose sources are considered diffuse. Dekiff, J.H., Remy, D., Klasmeier, J., Fries, E., 2014. Occurrence and spatial distribution of microplastics in sediments from Norderney. Environmental Pollution 186, 248–256. https://doi.org/10.1016/j.envpol.2013.11.019 Dris, R., Gasperi, J., Tassin, B., 2018. Sources and Fate of Microplastics in Urban Areas. A Focus on Paris Megacity. Freshwater Microplastics 69, 10–1007. Mani, T., Lorenz, C., Gerdts, G., Burkhardt-Holm, P., 2018. High Concentrations of Microplastics in the Bed Sediments of the Rhine River. Presented at the Micro20181, Lanzarote.
Keywords :	Microplastics, sédiments, Infra-red, Loire, Land-to-sea continium

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