Photolysis of the antidepressants amisulpride and desipramine in wastewaters: Identification of transformation products formed and their fate Meritxell Gros a,b , Mike Williams a, ⁎, Marta Llorca c , Sara Rodriguez-Mozaz c , Damià Barceló c,d , Rai S. Kookana a a Commonwealth Scientific and Industrial Research Organization (CSIRO), Land and Water Flagship, Waite Campus, Urrbrae, 5064 Adelaide, SA, Australia b Swedish University of Agricultural Sciences (SLU), Department of Aquatic Sciences and Assessment, Lennart Hjelms väg 9, 75007 Uppsala, Sweden c Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, C/Emili Grahit, 101 Girona, Spain d Water and Soil Quality Research Group, Department of Environmental IDAEA-CSIC, Jordi Girona 18-26, E-08034 Barcelona, Spain HIGHLIGHTS • Photolysis of both compounds resulted in several transformation products, some of which were previously unknown. • Short irradiation times may be adequate to degrade amisulpride whereas a longer exposure is required for desipramine. • Transformation of desipramine was enhanced by about three times due to indirect photolysis in wastewaters. • For desipramine, mixture acute toxicity increased after solar irradiation. • Photolysis is unlikely to be the main removal pathway for the two antidepressants during wastewater treatment. abstract article info Article history: Received 20 March 2015 Received in revised form 29 May 2015 Accepted 31 May 2015 Available online 8 June 2015 Editor: Adrian Covaci Keywords: Sewage Lagoon Photolysis Pharmaceuticals Transformation products High-resolution mass spectrometry Attenuation of pharmaceuticals due to natural sunlight is expected to be an important removal pathway in wastewater treatment plants using treatment lagoon systems. In this work, the photolysis of two antidepres- sants, amisulpride and desipramine, has been investigated in both ultrapure water and wastewater under simu- lated solar irradiation. Results showed that for amisulpride short irradiation times (t 1/2 approximately 3 h in pure water and 4 h in wastewater) were adequate to degrade the parent compound while a longer exposure period was required for desipramine (t 1/2 of approximately 36 h in pure water), although its degradation is enhanced almost three times by indirect photolysis in wastewaters. A significant number of transformation products (TPs) were identified for both pharmaceuticals by high-resolution mass spectrometry. In general, TPs formed are not persistent although acute toxicity tests for desipramine and its TPs showed an increase of the mixture toxicity after solar irradiation, suggesting that some TPs may be more toxic than the parent compound. In waste- waters collected from treatment lagoons, only amisulpride and one of its major TPs, TP 357, were detected. This indicates that long solar exposure times may be necessary for an effective elimination of these substances in lagoon systems or that photolysis may not be the main removal pathway for these particular compounds. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Discharges of effluents from municipal wastewater treatment plants (WWTPs) are an important pathway for pharmaceuticals to enter aquatic ecosystems. Several investigations have demonstrated that pharmaceuticals are only partially removed during conventional treat- ments applied in WWTPs (Jelic et al., 2011; Radjenovic et al., 2007; Gros et al., 2010). Some WWTPs also discharge effluents to lagoons for enhanced treatment, through settling and extended exposure to solar irradiation and microbial activity (Li et al., 2013). Lagoon-based waste- water treatment consists of wastewater flowing through shallow, open ponds with extended hydraulic retention times, typically between 7 and 20 days (Hoque et al., 2014). As an enhanced treatment process, lagoon-based treatments are less expensive and may be as equally effi- cient as conventional wastewater treatments in removing organic contaminants. Few studies, however, have evaluated the effectiveness of lagoons in removing organic pollutants and they only asses the removal of the par- ent compound (Hoque et al., 2014; Conkle et al., 2008; Lishman et al., 2006; MacLeod and Wonga, 2010; Camacho-Muñoz et al., 2012; Carlson et al., 2013). Science of the Total Environment 530–531 (2015) 434–444 ⁎ Corresponding author. E-mail address: Mike.Williams@csiro.au (M. Williams). http://dx.doi.org/10.1016/j.scitotenv.2015.05.135 0048-9697/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv