Joint studies of classical hydrochemical data and DOM characterization methods for environmental tracing issues. Application to Chevaline karst system (Choranche, SE France)

This combines hydrochemical data, classically used to environmental tracing, and monitoring of different Dissolved Organic Matter (DOM) types. The studied area is karst system of Choranche caves in Vercors (Isere - France) because several previous works and measuring equipment allowed a good knowledge of its behaviour. thanks to daily sampling of Chevaline outlet, from August to November 2009, and usual hydrochemical analyses (alkalinity, hardness, TOC), knowledge about hydrogeological behaviour of system has been allowed to improve. Analytical methods of DOM characterization have been used simultaneously to observe their temporal evolution (UV-Vis absorbance spectrometry, pectrofluorescence). They allowed (i) a methodological development to monitor non-absorbent organic molecules, until then not easy to observe, and (ii) to show that, thanks to detailed DOM studies, complementary informations about karst aquifer behaviour can be obtained, when usual environmental tracing methods seem not to be enough distinguishing.