ELIE EVENTS
Public Thesis Defense of Maëlle VILLANI
Public thesis defense of Maëlle VILLANI
"Dynamics of biogeochemical processes in permafrost landscapes : insights from the late shoulder season and deep winter"
19/10/2026 - 16:00
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Jury members:
President
Prof. Emmanuel HANERT (UCLouvain, Belgium)
Jury members
Prof. Yannick Agnan (UCLouvain, Belgium)
Prof. Marc BENEDETTI (IPGP, France)
Dr. Laure GANDOIS (CNRS and INP Toulouse, France)
Dr. Alexandre VOINOT (NRCan Geological Survey and Queen’s University, Canada)
Supervisor
Prof. Sophie OPFERGELT (UCLouvain, Belgium)
Abstract
Permafrost underlies about 25% of the Northern Hemisphere’s land surface and stores nearly twice as much carbon as the atmosphere. As the Arctic warms, permafrost thaw alters soil hydrology and redox conditions, mobilizing iron (Fe), associated metal(loid)s, and dissolved organic carbon (DOC) toward aquatic systems. Yet, the effects of these redox shifts on Fe, metal(loid)s, and DOC mobility during winter remain poorly constrained. This thesis investigates Fe, associated meta(loid)s, and DOC mobilization in soil and river waters at a discontinuous permafrost site in Healy (Alaska, USA) and a sporadic permafrost site in Abisko (Sweden), during the late shoulder season (i.e., the transitional period from the senescence of deciduous plants until the headwaters refreeze and cease to flow) and deep winter. We found that progressive soil freezing in Healy during the late shoulder season drives reducing conditions that mobilize metal(loid)s and DOC in soil waters. In Abisko, episodic snowmelt events during the late shoulder season induce water table fluctuations that control Fe and DOC mobilization in soil waters. In rivers, near-freezing soils in Healy reduce soil–river connectivity, whereas milder conditions with near-stagnant river flow in Abisko sustain lateral transfer of Fe and DOC. During deep winter, DOC transfer from lateral taliks to streams increases with warming without detectable increases in stream CO2 and CH4. Overall, the late shoulder season and deep winter emerge as biogeochemically active periods with spatially and temporally heterogeneous DOC mobility, underscoring the need to include winter fluxes in Arctic carbon budget models.
Public Thesis Defense of Riana RANDRESIHAJA
Public thesis defense of Riana RANDRESIHAJA
"Modelling storm surges in the Scheldt-North Sea continuum under present and future climate conditions"
18/11/2026 - 16:15
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President
Prof. Marnik VANCLOOSTER (UCLouvain)
Jury members
Dr. Jonathan LAMBRECHTS, secrétaire (UCLouvain)
Dr. Olivier GOURGUE (Royal Belgian Institute of Natural Sciences)
Prof. Xavier FETTWEIS (ULiège)
Prof. Emil STANEV (Helmholtz-Zentrum Hereon)
Supervisor
Prof Emmanuel HANERT, promoteur (UCLouvain)
Prof. Marilaure GRÉGOIRE, promotrice (ULiège)
Abstract
TBA
Public Thesis Defense of Hugo COUNOY
Public thesis defense of Hugo COUNOY
"Improving the interpretation and applicability of epiphytic lichen biomonitoring for air quality assessment"
"Advances in bioindication, bioaccumulation, and citizen science”
23/11/2026 - 16:00
SUD 01 - Croix du Sud - Louvain-la-Neuve
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Chairman
Prof. Emmanuel HANERT (UCLouvain)
Jury members
Prof. Gabrielle MARTIN (Université de Toulouse)
Prof. Guillaume LOBET (UCLouvain)
Prof. Nadine MATTIELLI (ULB)
Prof. Nathalie SEJALON-DELMAS (Université de Toulouse)
Prof. Emmanuel HANERT (UCLouvain)
Supervisors
Prof. Yannick AGNAN (UCLouvain)
Dr. Laure TURCATI (Sorbonne Université)
Abstract
Air pollution remains a major threat to human health and ecosystems, yet conventional monitoring networks are costly, too sparse to capture fine-scale variation in exposure, and restricted to a few pollutants. Biomonitoring with lichens offers a complementary approach, since these organisms respond to atmospheric conditions, integrate many contaminants over time and can be surveyed across large areas. However, inferring air quality from the composition of lichen communities (bioindication) remains hindered by identification difficulties and incomplete knowledge of how species respond to individual pollutants, while the contaminants accumulated in lichen tissues (bioaccumulation) are hard to trace back to their sources, notably because they reflect integrated and partly legacy inputs. This thesis aims to improve the interpretation and applicability of lichen bioindication and bioaccumulation. First, a European meta-analysis identifies species with consistent responses to NH3, NOx, SO2 and climate variables. These responses are then translated into operational indices which, tested in Wallonia (Belgium), partially discriminate NH3 from NOx. In the same region, trace elements accumulated in herbarium and contemporary samples of Xanthoria parietina reveal a marked, element-specific decline in enrichment since the 1960s and identify industry, non-exhaust traffic, and dust resuspension as the main current sources. Analyzing nitrogen content and δ15N indicates that isotopic signatures alone cannot discriminate sources in multi-source landscapes and vary with spatial scale. Finally, to open biomonitoring to non-specialists, the Lichens GO citizen science protocol is evaluated and adapted: targeted changes to sampling and identification procedures improve data quality without increasing sampling effort.
Overall, this thesis supports a more pollutant-specific, source-informed and widely deployable use of lichens to complement conventional monitoring.
Public thesis defense of Sabi Kidirou GBEDOUROROU
Public thesis defense of Sabi Kidirou GBEDOUROROU
"Dynamics of nitrogen in rainfed lowland rice intensification systems in Benin: characterization and modeling"
27/11/2026 - 16:15
Océan room - bâtiment de Serres - Croix du Sud - Louvain-la-Neuve
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Chairman
Prof. Frédéric GASPART (UCLouvain)
Jury members
Prof. Charles BIELDERS (Secretary, UCLouvain)
Dr. Bernard VANLAUWE ( Member, IITA, Kenya)
Dr. Pierre G. TOVIHOUDJI (Member, University of Parakou, Benin)
Supervisors
Prof. Marnik VANCLOOSTER (Supervisor, UCLouvain)
Prof. P. B. Irénikatché AKPONIKPE (Co-Supervisor, University of Parakou, Benin)
Abstract
TBA
Public Thesis Defense of Maxime BURON
Public thesis defense of Maxime BURON
"Estimating and mapping the habitat quality of bee pollinators at the agricultural landscape level: a combined approach of floral resources and pesticide exposure"
11/12/2026 - 16:00
SUD 03 - Croix du Sud - Louvain-la-Neuve
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Chairman
Prof. Emmanuel HANERT (UCLouvain)
Jury members
Prof. Anne-Laure JACQUEMART (UCLouvain, Belgium)
Prof. Mathilde BAUDE (Université d’Orléans, France)
Dr. Louis HAUTIER (CRA-W, Belgium)
Supervisors
Prof. Yannick AGNAN (UCLouvain)
Prof. Pierre DEFOURNY
Abstract
TBA