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H1 Fate of trace organics in the hyporheic zone of urban rivers
Doctoral candidate: Birgit Maria Müller 
Supervisors: PD Dr. Jörg Lewandowski , Prof. Ferdinand Hellweger , Dr. Anke Putschew , Prof. Okke Batelaan 
Trace organic contaminants (TrOCs) are anthropogenic chemicals including pharmaceuticals, industrial compounds, personal care products, pesticides and drugs. They mainly reach rivers with effluents of wastewater treatment plants (Kasprzyk-Hordern et al., 2008). Being released into the environment, they undergo natural removal processes such as microbial degradation, photolysis or sorption onto the sediment (Li, 2014). For the attenuation of TrOCs, the hyporheic zone, which is basically the streambed sediment, was found to play an important role due to diverse biological, chemical and physical processes occurring there. Amongst these processes, microbial metabolism has the biggest influence on TrOCs attenuation (Boano et al., 2014; Lawrence et al., 2013).
The hyporheic zone itself is located within the upper parts of a riverbed where groundwater infiltration or exfiltration take place (Fohrer et al., 2016). It is characterized by heterogeneous physio- and biogeochemical conditions as well as gradients due to the mixing of groundwater and surface water (Fischer et al., 2005; Storey et al., 2001).
- Figure 1: Graphical overview for the doctoral project H1. DOC: dissolved organic carbon, TP: transformation product, TrOC: trace organic compound
- © Müller
Profound knowledge on processes contributing to the attenuation of TrOCs in the hyporheic zone is necessary for an effective and sustainable water quality management. This is especially the case in densely populated areas as urbanization increases the pressure on water recourses and their quality. In cities such as Berlin, this is even more important due to a semi-closed water cycle. While some lab studies on attenuation of TrOCs have already been conducted under controlled conditions (Alidina et al., 2015; Hoppe-Jones et al., 2012; Rauch-Williams et al., 2010), there is still a lack of field experiments and sampling campaigns under natural conditions investigating:
- The linkage of TrOCs attenuation with seasonal variations of oxygen levels and temperature in the hyporheic zone
- The influence of dissolved organic carbon (DOC) as a metabolic co-substrate on microbial TrOCs attenuation (Maeng et al., 2011)
For this doctoral project, field studies and sampling campaigns have been and will be conducted using automatic surface water samplers and active pore water samplers (Schaper et al., 2018), the latter with minimal impact on the surrounding hyporheic zone. This enables the generation of high frequency time series of biogeochemical analytes as well as TrOCs concentrations along depth profiles from the surface water into the river bed sediments. Oxygen and other redox indicators are used to describe the redox zonation of the hyporheic zone. Furthermore, hyporheic fluxes are analysed using daily patterns of electric conductivity which are caused by regular discharge fluctuations of the wastewater treatment plant.
- Figure 2: Setting up the automatic surface water sampler.
- © Lewandowski
The methods applied proved to be suitable for generating high frequency time series of biogeochemical analytes as well as TrOCs concentrations in both, surface and pore water. First results suggest that the hyporheic zone is more efficient in removing TrOCs from a river than degradation processes in the surface water of the small urban River Erpe which is highly influenced by a wastewater treatment plant.
UWI projects: H2, H3, H4, F1 
UWI kollegiates: Hanna Schulz 
External cooperations: Flinders University in Adelaide, Australia 
Common topic: Interface urban hyporheic zones 
Alidina, M., Shewchuk, J., Drewes, J.E., 2015. Effect of temperature on removal of trace organic chemicals in managed aquifer recharge systems. Chemosphere, 122: 23-31. DOI:https://doi.org/10.1016/j.chemosphere.2014.10.064 
Boano, F. et al., 2014. Hyporheic flow and transport processes: Mechanisms, models, and biogeochemical implications. Reviews of Geophysics, 52: 603 - 679. DOI:10.1002/2012RG000417
Fischer, H., Kloep, F., Wilzcek, S., Pusch, M.T., 2005. A River's Liver – Microbial Processes within the Hyporheic Zone of a Large Lowland River. Biogeochemistry, 76(2): 349-371. DOI:10.1007/s10533-005-6896-y
Fohrer, N. et al., 2016. Hydrologie, 1. UTB, Bern, 320 pp.
Hoppe-Jones, C., Dickenson, E.R., Drewes, J.E., 2012. The role of microbial adaptation and biodegradable dissolved organic carbon on the attenuation of trace organic chemicals during groundwater recharge. Sci Total Environ, 437: 137-44. DOI:10.1016/j.scitotenv.2012.08.009
Kasprzyk-Hordern, B., Dinsdale, R.M., Guwy, A.J., 2008. The occurrence of pharmaceuticals, personal care products, endocrine disruptors and illicit drugs in surface water in South Wales, UK. Water Research, 42(13): 3498-3518. DOI:https://doi.org/10.1016/j.watres.2008.04.026 
Lawrence, J.E. et al., 2013. Hyporheic Zone in Urban Streams: A Review and Opportunities for Enhancing Water Quality and Improving Aquatic Habitat by Active Management. Environmental Engineering Science, 30(8): 480-501. DOI:10.1089/ees.2012.0235
Li, W.C., 2014. Occurrence, sources, and fate of pharmaceuticals in aquatic environment and soil. Environmental Pollution, 187: 193-201. DOI:https://doi.org/10.1016/j.envpol.2014.01.015 
Maeng, S.K., Sharma, S.K., Abel, C.D.T., Magic-Knezev, A., Amy, G.L., 2011. Role of biodegradation in the removal of pharmaceutically active compounds with different bulk organic matter characteristics through managed aquifer recharge: Batch and column studies. Water Research, 45(16): 4722-4736. DOI:https://doi.org/10.1016/j.watres.2011.05.043 
Rauch-Williams, T., Hoppe-Jones, C., Drewes, J.E., 2010. The role of organic matter in the removal of emerging trace organic chemicals during managed aquifer recharge. Water Res, 44(2): 449-60. DOI:10.1016/j.watres.2009.08.027
Schaper, J.L. et al., 2018. Hyporheic Exchange Controls Fate of Trace Organic Compounds in an Urban Stream. Environmental Science & Technology, 52(21): 12285-12294. DOI:10.1021/acs.est.8b03117
Storey, R.G., Fulthorpe, R.R., Williams, D.D., 2001. Perspectives and predictions on the microbial ecology of the hyporheic zone. Freshwater Biology, 41(1): 119-130. DOI:10.1046/j.1365-2427.1999.00377.x