Carbon sources and water-rock interactions in the Allier River, France

Abstract : The Allier river is one of major river in France as it is the main contributor of the Loire river, The Allier river present both natural environment upstream and a plain zone deeply impacted by mines and human activities. The original combination of d13C and d7Li data allow to decipher sources effects and in-situ phenomenon in the riverine inorganic carbon cycle such as mineral phases precipitation or equilibration with the atmosphere. These data show that the riverine system of the Allier is a mixing between DIC from organic decay produced in a natural environment (upstream) progressively enriched in DIC of anthropogenic origin (downstream) and deep carbon inputs implying thermo-water rock interactions.