Distribution of contaminant degraders and redox guilds and expression of degradation genes in stationary and non-stationary contaminant plumes

• Applicant: Professor Dr. Tillmann Lüders
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5470602

The aim of TP4B in this Research Unit is to understand how redox oscillations and hydraulic shifts influence the spatial distribution and activity of contaminant degraders and anaerobic microbial communities in the field. It is a central hypothesis of this Research Unit that increased mixing in contaminant plumes under non-stationary conditions can be expected to enhance net biodegradation activities. On the other hand, we hypothesize that well established biological degradation capacities (i.e. highly specialised degrader populations) are an essential prerequisite for effective biodegradation in highly reactive zones. Biodegradation can be hypothesized to decrease or even collapse transiently under redox fluctuations caused by hydraulic shifts, if sessile degrader populations suddenly face opposing biogeochemical conditions, and have to re-establish in different sediment strata. In the 2nd phase of funding of the FOR252, we have provided primary evidence that the qualitative and quantitative distribution patterns of important contaminant-degrading microbial populations are subject to unexpected temporal dynamics in the field. An observed “collapse” of the established degrader population was connected to pronounced temporal oscillations of the contaminant plume. These are novel findings that will help to establish a more detailed understanding of the factors that affect and control contaminant degrading microbial populations in the field. In the last 1.5 years of this Research Unit (12 months of funding we hereby apply for), we aim to further elaborate and more profoundly establish these concepts by continued time-resolved samplings in the field, addressing also short-time dynamics. Furthermore, an established luminescent bioreporter strain will be employed in 2D aquifer mesocosms to follow and model the development of a specific degrader population and activities over the establishment of a contaminant plume, and also under non-stationary conditions. Thus, simulations of the distribution of microbial degradation activities and their adaptation to increased mixing for the tanks will actually become testable with temporally and spatially resolved non-invasive data.

• DFG Programme: Research Units
• Subproject of: FOR 525: Analysis and Modelling of Diffusion/Dispersion-limited Reactions in Porous Media
• Participating Person: Professor Dr. Rainer Udo Meckenstock