Groundwater

Event Date: 
Wednesday, September 30, 2015 - 18:00 - 18:15
Institution: 
Macquarie University
Title: 

Aquifer microbial community assembly: do neutral processes dominate?

Abstract: 

Community assembly processes can be condensed into four categories: dispersal, selection, drift and speciation. We tested aquifer communities (of Archaea, Bacteria, Fungi, and Eukarya generally) for evidence that dispersal limitation and environmental selection play a role in determining community biodiversity and composition. We found only weak evidence for these processes at a regional scale of up to 250 km and spanning several significant dispersal barriers. I discuss the possibility that neutral (i.e. non-deterministic, non-selective) processes dominate in groundwater ecosystems, and the spatial scaling of these processes.

 

Event Date: 
Wednesday, September 25, 2013 - 07:00 - 08:00
Institution: 
Helmholtz Centre for Groundwater Ecology, Munich, Germany
Title: 

Limiting factors for anaerobic aromatic hydrocarbon degradation in contaminated aquifers and oil reservoirs

Abstract: 

 
Biography

  • Rainer Meckenstock studied biology at University of Konstanz, Germany 1985-1990. He finished with a thesis in the group of Prof. Winfried Boss on microbial sugar transport systems (molecular microbiology). He did his PhD at the Swiss Federal Institute of Technology (ETH) in Zürich, Switzerland, with a thesis on biochemistry of light-harvesting complexes of phototrophic bacteria (1990-1993) in the Institute of Molecular Biology and Biophysics with Prof. Zuber. During his post-doc at the Swiss Federal Institute of Environmental Science andTechnology (EAWAG) in the group of Dr. van der Meer in Dübendorf, Switzerland, he developed molecular methods to monitor trichlorobenzene-degrading microorganisms and their degradation activities in the environment (PCR, RT/PCR, in situ hybridisation) (1993-1995). He changed to the investigation of anaerobic degradation of aromatic hydrocarbons in the Microbial Ecology Group of Prof. Bernhard Schink, University of Konstanz, Germany, in 1996. Here, he isolated novel anaerobic BTEX and PAH-degrading organisms and studied the degradation pathways. A new method to study microbial activities in the environment with analysis of stable isotope fractionation was developed. Since 2000 he changed to the Center of Applied Geosciences at the University of Tübingen, Germany, and set up a Geomicrobiology group within the Chair of Environmental Mineralogy (Prof. Stefan Haderlein). Research topics were the anaerobic degradation of mono- and polycyclic aromatic hydrocarbons (BTEX, PAH), isotope fractionation as a means to monitor biodegradation in contaminated groundwaters, limitations of natural attentuation, and the reduction of iron minerals as electron acceptor. Since July 2003, he became the director of the Institute of Hydrology at GSF which changed its name to Institute of Groundwater Ecology at the beginning of 2004. In 2007 he was appointed as a full professor for Groundwater Ecology at the Life Science Center (WZW) of the Technical University of Munich.
Event Date: 
Wednesday, May 29, 2013 - 19:00 - 19:45
Institution: 
CSIRO
Title: 

Sediment Biobarriers for Chlorinated Aliphatic Hydrocarbons in Groundwater Reaching Surface Water

Abstract: 

 
This study explored the potential of eutrophic river sediments to attenuate the infiltration of chlorinated aliphatic hydrocarbon (CAH)-polluted groundwater discharging into the Zenne River near Brussels, Belgium. Active biotic reductive dechlorination of CAHs in the riverbed was suggested by a high dechlorination activity in batch- and column biodegradation tests performed with sediment samples, and by the detection of dechlorination products in sediment pore water. Halorespiring Dehalococcoides spp. were present in large numbers in the riverbed as shown by quantification of their 16S rRNA and reductive dehalogenase genes. By using DGGE-fingerprint analysis of relevant nucleic acid markers, it was shown that the Zenne River sediments were inhabited by a metabolically diverse bacterial community. A large diversity of sulfate-reducing bacteria, Geobacteraceae and methanogens, which potentially compete with halorespiring bacteria for electron resources, was identified. The high organic carbon level in the top of the riverbed, originating from organic matter deposition from the eutrophic surface water, resulted in a homogeneous microbial community structure that differed from the microbial community structure of the sediment underneath this layer. Monitoring of CAH concentrations and stable isotope ratios of the CAHs (δ13C) and the water (δ2H and δ18O), allowed to identify different biotic and abiotic CAH attenuation processes and to delineate their spatial distribution in the riverbed. Reductive dechlorination of the CAHs was the most widespread attenuation process, followed by dilution by unpolluted groundwater discharge and by surface water-mixing. During a 21-month period, the extent of reductive dechlorination ranged from 27 to 89% and differed spatially but was remarkably stable over time, whereas the extent of abiotic CAH attenuation ranged from 6 to 94%, showed large temporal variations, and was often the main process contributing to the reduction of CAH discharge into the river. Although CAHs were never detected in the surface water, CAHs were not completely removed from the discharging groundwater at specific locations in the riverbed with high groundwater influx rates. Therefore, it was concluded that an increase in the extent of biotransformation in the riverbed is needed for acceptance of the Zenne biobarrier as a viable remedial option for attenuation of discharging CAH-polluted groundwater.

Event Date: 
Wednesday, November 28, 2012 - 07:00 - 08:00
Institution: 
University of Sydney
Title: 

Biodegradation of dichloroethane by aerobic bacteria at the Botany Industrial Park

Abstract: 

The chlorinated hydrocarbon 1,2-dichloroethane (DCA) is a common pollutant of groundwater, and poses both human and environmental health risks. The Botany Industrial Park in south Sydney is heavily contaminated with DCA and other organochlorines. The main user of the site (Orica Ltd) operates a large groundwater treatment plant (GTP) on site to contain and remediate the DCA-contaminated groundwater. At present, remediation is done by air-stripping and thermal oxidation, but this is very costly and energy-intensive. Orica is interested in alternative technologies for treating the groundwater, including bioremediation. In 2010, a pilot scale membrane bioreactor (MBR) was set up to treat a fraction of the groundwater. The aims of our study were to identify DCA-degrading bacteria and genes in the GTP and on the site at large, define the community structure and ecological successions occurring in the MBR, develop a qPCR for catabolic genes in the DCA biodegradation pathway, and field-test this qPCR assay in the MBR and in a survey of groundwater in monitoring wells on the site. We discovered that DCA-degrading bacteria using a hydrolytic pathway (dhlA/dhlB genes) were widespread and diverse at this site, and that the dhlA gene was carried on a catabolic plasmid. The community in the MBR was dominated by alpha- and beta-proteobacteria, and was highly dynamic, changing dramatically in composition as the percentage of raw groundwater in the feed was increased. By combining dhlA qPCR and 16S pyrosequencing data, we found evidence that thus-far-uncultured species of Azoarcus may play a major role in DCA bioremediation in situ in the MBR.

Syndicate content