Gwenaël Imfeld soutiendra son habilitation à diriger des recherche intitulée "Transport of contaminants in wetland systems" / "Transport de contaminants en milieu humide" le 9 janvier à 14H.
Lieu : EOST, 1 rue Blessig, Amphithéâtre 2ème étage
Jury :
- Philippe Ackerer, LHyGeS ? Strasbourg (UMR 7517), France
- Olivier Atteia, Institut EGID-Bordeaux 3 (EA 4592), France
- Kümmerer, Leuphana University Lüneburg, Allemagne
- Ülo Mander, University of Tartu, Estonie
- Fabrice Martin-Laurent, INRA ? Dijon (UMR 1347), France
- Jérôme Rose, CEREGE ? Aix en Provence (UMR 7330), France
- Ralf Schulz, University of Koblenz-Landau, Allemagne
Résumé / Abstract :
Fifty years after ?Silent Spring?, the book of Rachel Carson that first lit in 1962 a beacon that continues to burn, the dangers and risks of the unrelenting use of pollutants cast a longer shadow than ever, as advances in scientific disciplines continue to document its consequences for human health and ecosystems. Understanding the transport of pollutants from all sources, toxic and diffuse, pollution in particular, represents a major challenge and have become of utmost importance at the social, environmental and economical levels for the preservation of soil and water resources. However, the hydro-biogeochemical processes governing the transport and biotransformation of industrial, agricultural or urban organic contaminants (e.g. solvents, pesticides) and heavy metals in hydrosystems are little known. Wetlands are ubiquitous biogeochemical hotspots characterised by dynamic interfaces between water, soil and organisms, which can intercept pollutant fluxes and improve water quality. Therefore, wetlands are insightful systems for better understanding the transport and biotransformation of contaminants with respect to the hydrological and biogeochemical characteristics.
The overall objective of my research is to identify, characterise and predict the transport and biotransformation of organic and inorganic contaminants in biogeochemically dynamic hydrosystems, such as wetlands. Emphasis is given on microbial processes that govern the reactive transport of contaminants in wetlands that are hydrologically connected to a contaminant source, such as a polluted aquifer, or an urban or agricultural catchment. My approach is to combine hydrological, isotopic, hydrochemical, microbial molecular ecology and reactive transport modelling methods and techniques to understand how hydrological and biogeochemical conditions control the reactive transport of contaminants in the environment. Following a presentation of the development of my scientific career, including past and on going scientific projects, teaching and animations, the major scientific outcomes of my research carried out between 2005 and 2012 on the transport of various contaminants in wetland systems are highlighted. My research has first focused on the biotransformation in wetlands receiving contaminated groundwater of chlorinated hydrocarbons, such as chlorobenzene and dichloroethylene. This first series of studies showed that different methods can be advantageously coupled to evaluate the transport and biodegradation of chlorinated hydrocarbons in wetlands, and enabled, for the first time, to characterise the dynamics of microbial processes and biogeochemical conditions determining the degradation of chlorobenzene and dichloroethenes in wetlands. I have then focused on the transport of herbicides, fungicides and insecticides in a stormwater wetland receiving agricultural runoff. This second series of studies showed that stormwater wetlands could efficiently remove pesticide mixtures in agricultural runoff during critical periods of pesticide use. However, fluctuations in the runoff regime and hydrochemical characteristics impact the removal rates of individual pesticides, and in particular glyphosate and its degradation product AMPA. These studies are the first to quantitatively evaluate the transport and attenuation of pesticides in a stormwater wetlands receiving runoff, with respect to the hydrological and hydrochemical conditions. We also anticipate our results to be a starting point for considering degradation products of runoff-associated pesticides during their transfer in wetlands, in particular when using stormwater wetlands as a management practice targeting pesticide attenuation.
These past and current scientific developments have provided the scientific and technical background for the research project ?PESTinWET-Transport and bioattenuation of chloroacetanilide herbicides in wetlands', which is presented in the third section of this thesis. Finally, the linkage between the scientific results, the research project presented here and other ongoing research developments is emphasised. In the future, research on biogeochemical processes governing transport of organic and inorganic contaminant in at water-soil-(micro-)organisms interfaces is essential to make way for widely accepted framework and paradigm for assessing, characterising and predicting micropollutants transport in continental hydrosystems, and in particular in environments at the terrestrial-aquatic interface.