Fluxes of redox equivalents in metabolic networks at active zones in aquifers

• Applicant: Privatdozent Dr. Hans Hermann Richnow
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2006 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5471696

The spatial and temporal distribution of reduced and oxidized carbon (e.g. CH4 and CO2), nitrogen, iron, manganese, and sulphur species is commonly used to analyse microbial mediated electron transfer reactions and to characterise the biogeochemical conditions in contaminated aquifers. However, the linkage of carbon, nitrogen, iron an sulphur cycles in aquifers with respect to electron flow mediated by chemolithoautotrophic communities is not thoroughly investigated yet. Reduced products from electron transfer reactions such as NH4+, Fe2+, S2-, and CH4 have the potential to support chemolithoautotrophic and heterotrophic microbial processes as electron donors, thus linking the nitrogen iron sulphur and carbon cycles in aquifers in various microbial mediated interactions. Once formed during organic carbon degradation, methane, ammonia or reduced sulphur species will be transported in the ground water, will leave the zone of formation and become potent electron donors for microbial processes in other geochemical zones of the aquifer. The microflora using these electron donors may compete for electron acceptors with organisms degrading contaminants. We will investigate the cascades of redox reactions coupling electron donor-acceptor interaction of heterotrophic and chemolithoautotrophic microbial processes at geochemical gradients. In particular, the transport of methane, ammonia and reduced sulphur species linking the metabolism of microbial communities over certain distance will be studied with respect to the regulation of carbon and electron lux in contaminated aquifers.

• DFG Programme: Research Units
• Subproject of: FOR 580: Electron Transfer Processes in Anoxic Aquifers
• Participating Persons: Dr. Kay Knöller; Professor Dr. Matthias Kästner