Thesis in ecology - environmental chemistry

The student will carry out his/her research at the interface between functional ecology and environmental chemistry, between the two university sites (EDYSAN in Amiens, ICMR in Reims) and the different study sites.
The EDYSAN unit (UMR CNRS 7058) has an expertise in historical forest ecology and has worked on the long-term impacts of ancient land uses (since ancient times) through current forest biodiversity. For the purposes of the thesis, EDYSAN will bring different skills: forest ecology, botany, plant biology, pedology, history, cartography, remote sensing.
The Environmental Chemistry group of the ICMR unit (UMR CNRS 7312) studies the behavior of organic and inorganic contaminants at the soil/water interface (retention, transfer, speciation) and at the soil/plant interface. It will provide the student with its expertise in analytical chemistry, sorption and speciation processes concerning the fate of contaminants in the environment (soil, water, plant).
The student will be co-supervised by professors from both units with complementary skills: Déborah Closset (EDYSAN) HDR lecturer in botany and plant ecology and Stéphanie Sayen (ICMR) HDR lecturer in environmental chemistry.
The student will be registered at the doctoral school Sciences, Technology, Health of Amiens (UPJV EDSTS 585).

The toxic legacy of the Great War is a major public health concern in northern and eastern France: the slow degradation of buried munitions releases chemical pollutants that contaminate water and soil. The aim of the thesis is to relate the transfer of contaminants in the environment to the functioning of forest ecosystems and agroecosystems that have developed on former battlefields. The aim is to better understand the phenomena taking place at the soil-vegetation interface of former battlefields, in order to identify chemical, ecological, biological and ecophysiological indicators (potentially remotely detectable) of exposure to pollutants inherited from the Great War. This interdisciplinary thesis topic (functional ecology and environmental chemistry) combines comparative and correlative approaches, in the laboratory and in Natura.
The work will consist, in mapping the woods and fields of the former front and back-front zones of the Great War, from the available archives. A regression analysis of the landscape will reconstitute the land uses before 1914 and today (cultivation vs. forest) in order to distinguish between old forests that have been reconstituted where they were already present before 1914, versus recent forests established on former fields. The rate of destruction in 1914-1918 (total, partial, zero) will also be reconstructed from available archives. These historical data will be confirmed by remote sensing of microtopography using a LiDAR equipped drone.
From this mapping, the study sites will be identified in the forest and the work will consist in characterizing the soil-vegetation complex, through vegetation surveys (phytosociological method) and physico-chemical soil analyses. The absence of species, the overabundance of others, the presence of chlorosis, the alteration of life-history traits, or variations in plant biomass will serve as indicators of past disturbances and pollution.
Finally, it will be necessary to measure different pollutants in the soil, soil water and plant tissues (target species, from forest environments and agrosystems), and then to "measure" and characterize the physiological alterations (respiration, photosynthesis, etc.) of the plants linked to the presence of these pollutants.
This study will be completed by experiments under controlled conditions in greenhouses: exposure to pollutants identified in natura, in order to identify a spectral signature of these pollutants. This signature will be sought in the field, using a remote sensing method.
The ultimate goal of this thesis will be to identify indicators of soil and water contamination and to produce a map of human exposure via water and food.