Duties
Project Rationale:
Coastal zones are on the front line of climate change and anthropogenic pressures. While rivers are recognized as major vectors of material transfer to the ocean, coastal groundwater remains a key component that is still poorly quantified. These diffuse fluxes, occurring through littoral sediments, transport nutrients, carbon, contaminants, and fine particles to coastal waters, thereby contributing to deoxygenation, eutrophication, and acidification of coastal waters, as well as sediment dynamics.
Project Description:
This PhD project aims to understand the role of groundwater discharge in the functioning and health of coastal ecosystems and addresses emerging challenges in coastal hydrogeology. It seeks to investigate and quantify the contribution of groundwater to coastal water chemistry and sediment dynamics by combining hydrogeochemical and hydrosedimentary budgets.
By integrating hydrogeological, geochemical, and coastal dynamics data, this project proposes a holistic approach that will deepen our understanding and contribute to the management—and thus the preservation—of this fragile ecosystem.
Objectives:
More specifically, the PhD project is structured around three main objectives:
- Quantify groundwater discharge at the scale of an island system in the St. Lawrence River, integrating different hydrostratigraphic contexts ;
- Evaluate major element fluxes derived from water–rock weathering and assess their role in the coastal carbon cycle, with particular emphasis on the impact of alkaline and nitrate inputs on the chemistry and biogeochemical balance of the St. Lawrence coastal waters;
- Examine the role of groundwater discharge in hydrosedimentary budgets to improve understanding of its impact on fine-particle dynamics and coastal morphodynamics.
Methods:
The PhD project will combine hydrogeological and oceanographic approaches and will include:
1) Seasonal fieldwork, including installation of piezometers; sampling of surface water, groundwater, soils, and sediments; LiDAR surveys; and thermal drone imaging;
2) Laboratory analyses, including general and isotopic geochemistry (stable isotopes of water, naturally occurring radon and radium isotopes) and biogeochemistry, with their interpretation using statistical software, among other tools; and
3) Hydrogeological modeling.
