Characterisation of rapid infiltration flows and vulnerability in a karst aquifer using a decomposed fluorescence signal of dissolved organic matter

Abstract

International audienceThe fluorescent properties of dissolved organic matter (DOM) have been used as natural tracers in various water systems. However, only few studies have focused on groundwater systems, specifically, on karst systems. The aim of this study was to develop the use of the DOM fluorescence signal as a natural tracer, considering the multiple compartments of a karst system. This method was applied to the Lez hydrosystem, which supplies the city of Montpellier with drinking water. The hydrodynamics and hydrochemistry of the spring were monitored beginning March 2006. The DOM fluorescence was measured by the excitation-emission matrix spectroscopy technique. The analysis of the total fluorescence signal confirms the efficiency of this tool to trace rapid infiltration flows. Moreover, the decomposition of the signal into different fluorophores complements the information provided by the total signal. Indeed, the fluorescence emitted by the humic compounds seems to be the ideal tool for identifying rapid infiltration flows. Nevertheless, the fluorescence of proteinlike compounds is better correlated with the inflow of faecal bacteria at the outlet. This decomposition of the fluorescence signal is an interesting way to provide information on both the rapid infiltration flow as well as the vulnerability of the karst aquifers

SNO KARST: A French Network of Observatories for the Multidisciplinary Study of Critical Zone Processes in Karst Watersheds and Aquifers

“…In particular, what is the role played by the karst compartment in sustaining low water levels, allowing for flood mitigation or triggering flood amplification (Jourde et al, 2007, 2014; Bailly‐Comte et al, 2008; 2009; Maréchal et al, 2008; Charlier et al, 2015b)? Should the presence of karst be taken into account in stochastic approaches for the predetermination of hydrological extremes? The influence of karst on the mass balance of transported elements on the continental surface: mineral and organic C cycle (Batiot et al, 2003; Binet et al, 2006; Blondel et al, 2010; Quiers et al, 2014), transfer, storage, and release of suspended sediments (Massei et al, 2006; Valdes et al, 2006; Fournier et al, 2009), and the respective contributions of mechanical and chemical erosion.…”

Dimension Reduction and Analysis of a 10-Year Physicochemical and Biological Water Database Applied to Water Resources Intended for Human Consumption in the Provence-Alpes-Côte d’Azur Region, France

“…Groundwater conveys information acquired during its journey from the surface to the aquifer [1]. Its composition reflects the inputs from the atmosphere, and the interactions with the vegetation cover, presence of agricultural or industrial activities, characteristics of the soil through which it percolated, and lithology of the geological formations that shelter the aquifers [2][3][4][5][6][7][8][9]. Thus, the chemical and bacteriological composition of the water is a source of information that can help characterize different landscape units and the impact of human and industrial activities [10].…”

Tracking of Karst Contamination Using Alternative Monitoring Technologies: Hidden River Cave Kentucky

“…Dye tracing literature has long dealt with "background fluorescence" as a nuisance (Smart & Karunaratne 2002), but a wide range of environmental contaminants have expression in fluorescence. For example, fuels, raw sewage, road runoff and overland flow can all be revealed in the fluorescence spectrum, as can leaking treated water (Hartell et al, 2007;Mudarra, Andreo, & Baker, 2010;Quiers et al, 2014.). However, none of these contaminants has a direct quantifiable fluorescence signature, and this indicates an empirical rather than analytical approach.…”