Dynamic of dissolved organic matter and trace elements in a steady state lake bottom layer : molecular size fractionation.

Patrick Albéric (1) , Didier Jezequel (2) , Eric Viollier (2) , Christian Défarge (1) , Pascale Gautret (1)

1 ISTO - Institut des Sciences de la Terre d'Orléans
2 IPGP - Institut de Physique du Globe de Paris

Dissolved organic matter (DOM) in aquatic systems interacts with most processes including redox reactions, trace elements complexation, sorption and sedimentation. The complex nature of DOM in natural waters suggests that all the fractions constituting it do not contribute in the same way to its reactivity. The total stock of DOM can be split by various means like the difference in size of the molecules or the difference in affinity for adsorbent phases. The deep and stable layers of meromictic lakes are of a particular interest for the study of the mechanisms controlling the behaviour of chemical elements in natural systems. Quasi stationary conditions unroll and stratify the processes through a certain thickness of the water column. In the deep layer of the lake Pavin (Massif-Central, France), solutes dispersing from the water-sediment interface (92 meter depth) cross a succession of levels characterized by different physicochemical and microbiological conditions (redox conditions, interactions with neoformed or settling particles, bacterial metabolic types) before to reach the oxic layer around 60 meter depth (Viollier et al., 1995, 1997, Lehours et al., 2003).

Domaines: Géochimie

Patrick Albéric, Didier Jezequel, Eric Viollier, Christian Défarge, Pascale Gautret. Dynamic of dissolved organic matter and trace elements in a steady state lake bottom layer : molecular size fractionation.. IMOG 2007, Sep 2007, Torquay, United Kingdom. pp.P78-MO. ⟨insu-00189196⟩