Abstract
Water resources are a major issue due to their great vulnerability to global change (climate change,population growth, changing lifestyles). Groundwater in karst aquifers is an important resource,accounting for 25% of the world's drinking water supply and 40% in France (Chen et al., 2017).However, the understanding of the functioning of these aquifers is limited due to their highheterogeneity. The study of these aquifers thus relies heavily on natural tracing approaches to smoothout these heterogeneities at the scale of the system under study.The aim of this thesis is to improve a specific tracer, the fluorescence of organic matter, and todevelop a natural tracer of the types of limestone through which the water flows. Sampling andanalysis performed at a bi-monthly time scale from june 2020 to october 2021 have led to theconstitution of a new data set quantifying natural fluorescence, trace and major chemistry, totalorganic carbon of 16 springs and underground flows of the Fontaine de Vaucluse aquifer, as well asthe chemistry of 107 rock samples representative of different types of limestone.These results allowed (i) to establish a methodological review of the current use of fluorescenceindices and to propose technical and conceptual evolution paths, (ii) to reconstruct the qualitativerelationship between transit time and natural fluorescence, (iii) to highlight the potential of traceelements as a natural tracer of the types of limestones crossed by the water.