FOR 580 ZWI
The contribution of low-molecular weight acids (LMWA) and dissolved organic sulfur compounds (DOSC) to the effects of dissolved organic matter (DOM) on redox processesVon 02/2006
Projektleiter: Christian Zwiener
Mitarbeiter: Carsten Jobelius
Bewilligung: FOR 580 Electron Transfer Processes in Anoxic Aquifers
In anoxic aquifers organic matter can be degraded biochemically under reduction of sulfate and ferric iron. The occurrence of aromatic and heterocyclic low-molecular weight acids (LMWA) has been attributed to metabolic and co-metabolic degradation pathways in anoxic aquifers. LMWA can make up a considerable portion of dissolved organic matter (DOM) in zones of high substrate concentrations and high biodegradation activity and therefore affect the biotic and abiotic reactivity of iron species in crystalline, colloidal or dissolved form. Furthermore it is expected that in sulfide rich environments as they occur under sulfate reducing conditions sulfur will be incorporated into dissolved organic matter (DOM) and thus produce dissolved organic sulfur compounds (DOSC) which considerably affect the properties of DOM concerning complexation, interaction with surfaces and redox reactions. In the proposed project we intend to identify the contribution of low-molecular weight acids (LMWA) and dissolved organic sulfur compounds (DOSC) to dissolved organic matter (DOM) in anoxic aquifers by analysis of field samples and by laboratory studies on sulfur incorporation into DOM. Furthermore, the effect of LMWA and DOSC to the effects of DOM on iron-based redox processes and colloid formation and reactivity will be investigated by electrochemical and spectroscopic analysis techniques in laboratory experiments.