Interstitial waters were collected from Lake Aiguebelette sediment, Savoy, France, using an in situ sampler. Major ions, nutrients and trace metals Fe and Mn were measured. Early diagenesis in these sediments leads to the release of all the investigated elements. ΣPO4, NH+4 and H4SiO4 demonstrate significant concentration gradients reflecting organic matter decomposition. Thermodynamic calculations suggest that calcite, which precipitates from the overlying waters, dissolves in the pore fluids. A simplified model is presented to account for the increase of Ca2+, Alk and H+ concentrations with depth. Mineralogical investigations using SEM, TEM, microprobe analysis and step dissolution of the sediment complete and corroborate the conclusions based on the study of interstitial waters (i.e. calcium carbonate and silica dissolution).
ASJC Scopus subject areas
- Geochemistry and Petrology