P5 Pollutant Transformations at the Water-Rock Interface

People Involved

Principal Investigators

Prof. Dr. Sara Kleindienst

University of Tübingen, Microbial Ecology (now at ISWA, Stuttgart University)

Prof. Dr. Andreas Kappler

University of Tübingen, Geomicrobiology

Prof. Dr. Peter Grathwohl

University of Tübingen, Hydrogeochemistry

Researchers

Dr. Karsten Osenbrück

Senior Scientist, University of Tübingen, Hydrogeochemistry (until 2021)

Dr. Sergey Abramov

PostDoc, University of Tübingen, Microbial Ecology (since 2020)

Dr. Eva Blendinger (associated)

Senior Scientist, University of Tübingen, Hydrogeochemistry (until 2022)

Dr. Nia Blackwell

PostDoc, University of Tübingen, Microbial Ecology (until 2020)

Dr. Natalia Jakus

PhD candidate, University of Tübingen, Geomicrobiology (graduated 2021)

Elena Petrova, MSc (associated)

PhD candidate, University of Tübingen, RTG Hydrosystem Modelling

Dr. Ana-Neva Visser, MSc

PhD candidate, University of Tübingen, Geomicrobiology (graduated 2018)

Research Questions and General Approach

Research Questions

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

General Approach of P5

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.

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