Fate of b-blockers in aquifer material under nitrate reducing conditions: Batch experiments Manuela Barbieri a,⇑ , Tobias Licha b , Karsten Nödler b , Jesús Carrera a , Carlos Ayora a , Xavier Sanchez-Vila c a GHS, Dept. of Geosciences, Institute of Environmental Assessment and Water Research, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain b Hydrochemistry Group, Dept. of Applied Geology, Geoscience Centre of the University of Göttingen, Goldschmidtstr. 3, 37077 Göttingen, Germany c GHS, Dept. of Geotechnical Engineering and Geosciences, Universitat Politècnica de Catalunya – BarcelonaTech (UPC), Jordi Girona 1-3, Modul D-2, 08034 Barcelona, Spain highlights " Fate of three b-blockers in aquifer material, denitrifying conditions, batch tests. " Abiotic and bio-activity related processes affecting atenolol. " Atenolol biotransformed to atenololic acid; quantitative study, zero order kinetics. " No mineralization for atenolol; atenololic acid stable under the studied conditions. " Abiotic processes dominating the decline of metoprolol and propranolol. article info Article history: Received 10 January 2012 Received in revised form 10 May 2012 Accepted 14 May 2012 Available online 6 June 2012 Keywords: Atenolol Metoprolol Propranolol Atenololic acid Sorption Biotransformation abstract The fate of the three environmentally relevant b-blockers atenolol, metoprolol and propranolol has been studied in batch experiments involving aquifer material and nitrate reducing conditions. Results from the about 90 d long tests indicate that abiotic processes, most likely sorption, jointly with biotransformation to atenololic acid were responsible for the 65% overall removal observed for atenolol. Zero order kinetics, typical of enzyme-limited reactions, controlled the transformation of this beta blocker to its correspond- ing carboxylic acid. The mass balance evidences that no mineralization of atenolol occurs in the biotic experiment and that atenololic acid is more stable than its parent compound under the studied condi- tions. This finding stresses the importance of considering atenololic acid as target compound in the envi- ronmental studies on the fate of atenolol. For metoprolol and propranolol the results from the experiment suggest a slower sorption to be the dominant removal process, which led to final decreases in concentra- tions of 25–30% and 40–45%, respectively. Overall, the removals observed in the experiments suggest that subsurface processes potentially constitute an alternative water treatment for the target beta-blockers, when compared to the removals reported for conventional wastewater treatment plants. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Beta-blockers (b-adrenergic receptor antagonists) are a class of widely prescribed cardiovascular drugs, used for the treatment of hypertension, cardiac arrhythmias, cardio protection after heart at- tacks, and anxiety disorders. After excretion, substantial amounts of these drugs get into the wastewater and end up in sewage treat- ment plants. Conventional wastewater treatments cannot remove them efficiently (Lin et al., 2009; Radjenovic et al., 2009; Gabet- Giraud et al., 2010; Gros et al., 2010). Therefore, b-blockers are dis- charged into surface waters, where indeed they have been detected at concentrations ranging from ng L 1 to lgL 1 (Kasprzyk-Hordern et al., 2008; Muñoz et al., 2009; Martínez Bueno et al., 2010; Nödler et al., 2011). Ecotoxicological studies reported b-blockers to affect the aquatic organisms, propranolol being the most harmful one (Fent et al., 2006; Küster et al., 2009). Several studies have thus been devoted to foster the understanding of their behaviour in aquatic-sediment systems. Such studies focus on phototransforma- tion, aerobic biotransformation and sorption to river sediments rich in organic carbon (Andreozzi et al., 2003; Liu and Williams, 2007; Yamamoto et al., 2009; Ramil et al., 2010). However, infor- mation on their fate in subsurface environments, especially under reducing conditions, is still scarce. Kibbey et al. (2007) studied the adsorption of nadolol, metoprolol and propranolol to a natural alluvial material, as well as to six individual mineral subcompo- nents of the sediments in batch experiments. Their results sug- gested that hydrophobicity serves as a predictor of adsorption even to low carbon sorbents, with propranolol, the most hydropho- bic compound studied, adsorbing to the greatest extent. At river 0045-6535/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2012.05.019 ⇑ Corresponding author. Tel.: +34 934006100x1640. E-mail address: manuela.barbieri1@gmail.com (M. Barbieri). Chemosphere 89 (2012) 1272–1277 Contents lists available at SciVerse ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere