A new application of passive samplers as indicators of in-situ biodegradation processes Angel Belles a, b, * , Claire Alary a, b , Justine Criquet c , Gabriel Billon c a Mines Douai, LGCGE-GCE, F-59508, Douai, France b Univ. Lille, F-59500, Lille, France c LASIR UMR CNRS 8516, University Lille 1 Sciences and Technologies, Villeneuve d'Ascq, France highlights graphical abstract  Passive samplers were used with tracer compounds to analyze degra- dation processes.  Degradation increases the dissipation of labeled nitro-PAH from passive samplers.  In-situ nitro-PAH degradation was demonstrated in field sediments. article info Article history: Received 5 June 2016 Received in revised form 19 August 2016 Accepted 23 August 2016 Handling Editor: Caroline Gaus Keywords: Passive samplers Biodegradation Sediment Nitro-PAH abstract In this paper, a method for evaluating the in-situ degradation of nitro polycyclic aromatic hydrocarbons (nitro-PAH) in sediments is presented. The methodology is adapted from the passive sampler technique, which commonly uses the dissipation rate of labeled compounds loaded in passive sampler devices to sense the environmental conditions of exposure. In the present study, polymeric passive samplers (made of polyethylene strips) loaded with a set of labeled polycyclic aromatic hydrocarbons (PAH) and nitro- PAH were immersed in sediments (in field and laboratory conditions) to track the degradation pro- cesses. This approach is theoretically based on the fact that a degradation process induces a steeper concentration gradient of the labeled compounds in the surrounding sediment, thereby increasing their compound dissipation rates compared with their dissipation in abiotic conditions. Postulating that the degradation magnitude is the same for the labeled compounds loaded in polyethylene strips and for their native homologs that are potentially present in the sediment, the field degradation of 3 nitro-PAH (2- nitro-fluorene, 1-nitro-pyrene, 6-nitro-chrysene) was semi-quantitatively analyzed using the devel- oped method. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Regulated PAH (16 compounds according to the USEPA) are among the main compound classes responsible for sediment pollution. They produce numerous degradation products, and their occurrence, persistence and fate in the aquatic environment have been studied extensively. Conversely, the occurrence and persis- tence of nitro polycyclic aromatic hydrocarbons (nitro-PAH), are rarely reported in the literature, although they have stronger carcinogenic and mutagenic activities than do the parent PAH (Yaffe * Corresponding author. Ecole des Mines de Douai, Department of Civil and Environmental Engineering, 764 Boulevard Lahure, 59500, Douai, France. E-mail address: angel.belles-limeul@mines-douai.fr (A. Belles). Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere http://dx.doi.org/10.1016/j.chemosphere.2016.08.111 0045-6535/© 2016 Elsevier Ltd. All rights reserved. Chemosphere 164 (2016) 347e354