Interaction of iron species and colloids with dissolved organic matter (DOM), dissolved organic sulfur compounds (DOSC) and low-molecular weight acids (LMWA)

• Applicant: Professor Dr. Christian Zwiener
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2006 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5471696

Specific biochemical and co-metabolic pathways of microbial degradation often form unique extracellular intermediates or metabolites, which can be used to indicate in situ electron transfer processes in aquifers. Arylsuccinate derivatives have emerged as potentially universal metabolic biomarkers for the transformation of toluene, xylene, ethylbenzene, and methylnaphthalene under anaerobic conditions. They were identified in laboratory cultures and partly in field samples. Their occurrence and distribution in the field has been neither investigated yet systematically, nor were the geochemical and hydraulic parameters investigated that may influence formation and further turnover of metabolites. Therefore, we will use in this project succinic acid derivatives and other acidic aromatic or aliphatic metabolites to monitor and understand the transformation of organic compounds by electron transfer processes. Data of the occurrence and spatial distribution of metabolites will be further used to elucidate their role as electron donors and to estimate the relevance of the electron donor function. For that purpose we will use column experiments with pure cultures to investigate the formation and turnover of specific metabolites (e.g. arylsuccinates, arylcarboxylic acids, low-molecular weight acids) and influencing parameters. The data obtained from those experiments will be used for reactive transport modeling. The calibrated model will then be used to simulate metabolite occurrence and distribution in different scenarios. Bioreactor experiments will address the question on contaminant degradation and metabolite formation/turnover with an inoculum of non-contaminated peat land under different geochemical conditions (boundary conditions). Metabolite accumulation will be of particular interest in this context. Field measurements will be performed in geochemically reactive zones of the site, where we will investigate metabolite pattern, their spatial distribution and accumulation. Analytical methods mainly with liquid chromatography-tandem mass spectrometry (LC-MS-MS) combined with different derivatization reactions will be developed to guarantee successful metabolite analysis in small sample volumes of column experiments and in groundwater samples of field sites.

• DFG Programme: Research Units
• Subproject of: FOR 580: Electron Transfer Processes in Anoxic Aquifers
• Participating Person: Professor Dr. Fritz Frimmel