Temperature dependent redox zonation and attenuation of wastewater-derived organic micropollutants in the hyporheic zone Victoria Burke a, ⁎, Janek Greskowiak a , Tina Asmuß a , Rebecca Bremermann a , Thomas Taute b , Gudrun Massmann a a Carl von Ossietzky University of Oldenburg, Department of Biology and Environmental Sciences, Working Group Hydrogeology and Landscape Hydrology, D-26111 Oldenburg, Germany b Freie Universität Berlin, Institute of Geological Sciences, Malteserstr. 74-100, 12249 Berlin, Germany HIGHLIGHTS • Attenuation of organic micropollutants during infiltration is temperature influenced. • Changes in temperature significantly impact the redox milieu. • Temperature and redox dependencies were found for nearly all investigated compounds. • The first meter of infiltration is highly reactive regarding micropollutant attenuation. abstract article info Article history: Received 8 November 2013 Received in revised form 17 February 2014 Accepted 21 February 2014 Available online 15 March 2014 Keywords: Bank filtration Biodegradation Column experiments Industrial agents Pharmaceuticals Redox conditions The hyporheic zone - a spatially fluctuating ecotone connecting surface water and groundwater - is considered to be highly reactive with regard to the attenuation of organic micropollutants. In the course of the presented study an undisturbed sediment core was taken from the infiltration zone of a bank filtration site in Berlin and operated under controlled laboratory conditions with wastewater-influenced surface water at two different temperatures, simulating winter and summer conditions. The aim was to evaluate the fate of site-relevant micropollutants, namely metoprolol, iopromide, diclofenac, carbamazepine, acesulfame, tolyltriazole, benzotriazole, phenazone and two phenazone type metabolites, within the first meter of infiltration dependent on the prevailing temperature. A change in temperature resulted in a development of significantly distinct redox conditions. Both temperature dependencies and related redox dependencies were identified for all micropollutants except for benzotriazole and carbamazepine, which behaved persistent under all conditions. For the remaining compounds degradation rate constants generally decreased from warm and oxic/penoxic/suboxic over cold and oxic/penoxic to warm and manganese reducing (transition zone). Individual degradation rate constants ranged from 0 (e.g. diclofenac, acesulfame and tolyltriazole in the transition zone) to 1.4 × 10 -4 s -1 for metoprolol under warm conditions within the oxic to suboxic zone. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The occurrence of organic micropollutants within the aquatic environment has been frequently addressed throughout the literature published in recent years and is the topic of numerous review articles (e.g. Burkhardt-Holm, 2010; Jones et al., 2001; Kümmerer, 2009; Schwarzenbach et al., 2006). The entry pathways are diverse. Within urban areas, organic micropollutants are mainly introduced into the water cycle via sewage systems. As contaminants such as pharmaceuti- cal residues, disinfection products and industrial agents are constituents of municipal and industrial sewage, and they are discharged into wastewater treatment plants where some of them are not or only incompletely removed (e.g. Vieno et al., 2007). In partly closed water cycles, treated wastewater containing residuals of these pollutants is discharged into the surface water and thus resupplied to the water cycle. Apart from treated wastewater as the primary source of organic micropollutants in urban surface waters, runoff from sealed areas may significantly contribute to their contamination as well (e.g. Gan et al., 2012; Meyer et al., 2011). By infiltration of (polluted) surface water into the subsurface, a process which is frequently induced during managed aquifer recharge (MAR), organic micropollutants may conse- quently be recharged to groundwater (e.g. Heberer, 2002). The interface between the entities surface water and groundwater – also referred to as the hyporheic zone – is described as a spatially Science of the Total Environment 482–483 (2014) 53–61 ⁎ Corresponding author. Tel.: +49 441 7984683; fax: +49 441 7983769. E-mail address: victoria.burke@uni-oldenburg.de (V. Burke). http://dx.doi.org/10.1016/j.scitotenv.2014.02.098 0048-9697/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv