Groundwater in fractured limestone aquifers is often polluted by nitrate and pesticides, including legacy compounds such as atrazine. Due to long groundwater residence-times in these aquifers, microbial activities associated with pollutant turnover may substantially influence the fate of pollutants. A particular example is denitrification, which depends on the availability of electron donors such as organic carbon or Fe(II) minerals within the rock matrix. Further, storage of pollutants (e.g. atrazine) in immobile water of the rock matrix may become relevant and impact contaminant loads in these systems. A multidisciplinary approach is used to:
Determine the locations of pollutant (nitrate, atrazine) turnover in fractured rock aquifers
Identify microbial key players mediating these processes and study their physiology
Quantify rates of microbial pollutant turnover
Examine factors that limit microbial activities and associated pollutant transformations
A combination of field studies and laboratory experiments is employed to address the above mentioned research objectives:
To characterize reactive zones and determine residence and exposure times, rock and groundwater samples are collected for petrologic (e.g. sediment facies, potential electron donors) and geochemical analyses (e.g. age tracers, major and trace elements, isotopes).
To examine microbial key players of pollutant turnover and their metabolic capabilities in situ, molecular tools (e.g. 16S rRNA amplicon sequencing and omics) are applied to samples from the fractured aquifer.
To quantify pollutant turnover, examine the factors limiting pollutant turnover, identify the involved microorganisms, and determine sorption as well as diffusion of pollutants, laboratory experiments using aquifer limestone material are conducted.
Achievements
Identification and Characterization of Zones with High Denitrification Potential
Isotope-Geochemical Investigations to Determine the Fate of Nitrate
Isolation of Enrichment Culture Capable of Denitrification Coupled to Oxidation of Fe(II)-Minerals
Molecular and OMICS Methods to Detect Microbial Key Players and Genomic Potential
Travel-Time Based Modelling to Detect Transport Limitations of Denitrification
Drilling Campaign at Baisingen to Attain Contamination-Free Rock Samples
Picture and Video Gallery
07 September 2020: Research drilling to unravel microbial nitrate degradation in a fractured rock groundwater system
In Cooperation with the Center for Media Competence at the University of Tübingen CAMPOS produced a short video showing background and details of the aseptic drilling at the Baisingen research site: P5 researchers (Jun. Prof. Sara Kleindienst, Dr. Karsten Osenbrück) explain goals and plans of their project.