Assessment of seasonal variations in persistent organic pollutants across the region of Tuscany using passive air samplers * Victor H. Estellano a, b , Karla Pozo a, b, c, * , Petra P  ribylov  a a , Jana Kl  anov  a a , Ond  rej Audy a , Silvano Focardi b a RECETOX Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk University, Kamenice 753/5, Pavilion A29, 625 00 Brno, Czech Republic b Department of Physical, Earth and Environmental Sciences, University of Siena, Via Mattioli 4, 53100, Siena, Italy c Facultad de Ciencias, Universidad Cat olica Santísima Concepci on, Alonso de Ribera 2850, P.C. 407 01 29 Concepci on, Chile article info Article history: Received 22 February 2016 Received in revised form 30 August 2016 Accepted 31 August 2016 Available online xxx Keywords: POPs PAS-PUF Seasonal variability Urban and rural sites Tuscany abstract Concentrations of persistent organic pollutants (POPs) were measured for an entire year in the region of Tuscany, Italy. Passive air samplers consisting of polyurethane foam (PUF) disks were deployed over four sampling periods of 3e5 months from April 2008 to July 2009 in urban (n ¼ 6) and rural (n ¼ 4) sites. The aim of the study was to characterize the spatial and seasonal variations in selected POPs. The POP concentrations (pg m 3 ) in the air were dominated by dichlorodiphenyltrichloroethane and metabolites (DDTs) and polychlorinated biphenyls ( P 7 PCBs). DDTs, and P 7 PCBs showed a clear decreasing urban > rural gradient. The concentrations of DDTs and PCBs were up to 10 and 6 times higher, respectively, in urban sites than in rural sites. P 7 PCBs showed a significant correlation with the ur- banized areas located <5 km around the sampling sites. For hexachlorocyclohexanes (HCHs), a-HCH concentrations were similar at both sampling sites and were found to be quite uniform during the four sampling periods. Seasonal fluctuations were observed for DDTs, and P 7 PCBs, with the highest con- centrations observed during period 4 (summerespring); this is most likely due to a temperature-driven re-emission from local sources. These findings were also supported by an air back trajectory analysis in the study area. This study contributes new information about POP levels in the Italian atmosphere and demonstrates the feasibility of using PUF disks to simultaneously assess seasonal concentrations at different sampling sites. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Persistent organic pollutants (POPs) are a heterogeneous group of chemicals of particular concern because of their persistence, bioaccumulation, biomagnification, and toxicity (Roots et al., 2010). The Stockholm Convention (SC) on POPs was adopted in 2001 and was enforced in 2004 (Stockholm Convention, 2015). Initially, only 12 chemicals were recognized as POPs; more recently at the sev- enth conference of the parties, additional chemicals were included in the SC (Stockholm Convention, 2015). Currently, Italy and Malta are the only European countries that have not ratified the SC on POPs (Stockholm Convention, 2015). However, because Italy is part of the European Union (EU) and the EU is a signatory of the SC on POPs, the production and commercialization of POPs are banned in Italy. Because of the wide usage of POPs as pesticides, they are directly emitted into the atmosphere as a spray. A large amount is released into the air over a wide range as a product of combustion and many other industrial processes (De Laurentis et al., 2009) and by an agricultural spray drift, post application volatilization, and wind erosion of soil. These emissions are influenced by numerous physical and chemical factors (Bogdal et al., 2013). The atmosphere is a primordial medium for POP transport and responds relatively quickly to changes in POPs emission; conse- quently, it has been recognized as a key medium in the Global Monitoring plan of the SC on POPs, which intends to support the evaluation of the effectiveness of the SC (Stockholm Convention, 2015). Furthermore, the UNEP Guidance promotes the use of * This paper has been recommended for acceptance by Prof. von Hippel Frank A. * Corresponding author. Department of Physical, Earth and Environmental Sci- ences, University of Siena, Via Mattioli 4, 53100, Siena, Italy. E-mail addresses: pozo@recetox.muni.cz, kpozo@ucsc.cl (K. Pozo). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol http://dx.doi.org/10.1016/j.envpol.2016.08.092 0269-7491/© 2016 Elsevier Ltd. All rights reserved. Environmental Pollution xxx (2017) 1e8 Please cite this article in press as: Estellano, V.H., et al., Assessment of seasonal variations in persistent organic pollutants across the region of Tuscany using passive air samplers, Environmental Pollution (2017), http://dx.doi.org/10.1016/j.envpol.2016.08.092