First records of polycyclic aromatic hydrocarbons and metals in sediments from a shallow lake in the Pampean–Patagonian region (Argentina) Ana L. Oliva A,F , Noelia S. La Colla A , Andre ´ s H. Arias A,B , Sandra E. Botte ´ A,C , Gerardo M. E. Perillo A,D and M. Cintia Piccolo A,E A Instituto Argentino de Oceanografı ´a (IADO – CONICET/UNS), Camino La Carrindanga 7500 B8000FWB Bahı ´a Blanca, Argentina. B Departamento de Quı ´mica, Universidad Nacional del Sur, Avenida Alem 1253, B8000DIC Bahı ´a Blanca, Argentina. C Departamento de Biologı ´a, Bioquı ´mica y Farmacia, Universidad Nacional del Sur, Avenida Alem 1253, B8000DIC Bahı ´a Blanca, Argentina. D Departamento de Geologı ´a, Universidad Nacional del Sur, Avenida Alem 1253, 2 Piso B8000DIC Bahı ´a Blanca, Argentina. E Departamento de Geografı ´a y Turismo, Universidad Nacional del Sur, 12 de Octubre 1198, B8000DIC Bahı ´a Blanca, Argentina. F Corresponding author. Email: anaoliva@criba.edu.ar Abstract. This study evaluated, for the first time, organic and metal contaminants in sediments from Argentinean saline lakes, specifically La Salada shallow lake, a small polymictic lake on the south border of the Pampean region. The concentration of 16 priority polycyclic aromatic hydrocarbons (PAHs) and 8 metals (Cd, Cu, Cr, Fe, Mn, Ni, Pb and Zn) was assessed and the ecotoxicological effects of these pollutants were examined. The total concentration of the 16 PAHs ranged from 12.55 to 10 679.48 ng g À1 dry weight, with a predominance of four-ringed PAHs. Molecular ratio analysis showed pyrolytic sources as the main source of PAHs. Among the metals, Mn, Fe and Zn had the highest concentrations in sediments. General metal levels revealed a multiplicity of point sources and rock weathering as their main source. Regarding the potential ecotoxicological effects, adverse effects may be expected from PAHs because several compounds exceeded the sediment quality guidelines threshold effect level and likely effect level. Conversely, metal levels were below levels specified in safety guidelines. These results are interpreted in an international context, providing information that addresses a gap in the pollution record of Argentinean lakes, and should have strong implications for future planning management. Received 23 August 2018, accepted 5 February 2019, published online 18 April 2019 Introduction Pollution of aquatic environments by metals and xenobiotics such as polycyclic aromatic hydrocarbons (PAHs) is of major concern worldwide (Barlas et al. 2005; Chang et al. 2006; Cui et al. 2011). Their persistence, ubiquity, toxicity and carcino- genic and mutagenic properties make them important among environmental pollutants. The US Environmental Protection Agency (US EPA) includes 16 PAHs as priority compounds (US Environmental Protection Agency 1993); moreover, according to the US EPA and the International Agency for Research on Cancer (2010), over half of these are potentially carcinogenic to humans. Even though PAHs may have natural origins, anthro- pogenic activities are generally considered the major source of PAHs released into the environment. In the case of metals, even though many of them are essential for living organisms (e.g. Zn, Cu, Mn, Fe, Ni and Cr), others, such as Cd and Pb, have no known function in biological systems (non-essential metals). Moreover, both essential and non-essential metals may have toxic effects at certain concentrations (Merciai et al. 2014). Lakes are sensitive ecosystems that integrate the effects of diverse stressors in the watershed (Adrian et al. 2009; Williamson et al. 2014). These systems are affected by adjacent terrestrial processes, and their normally long water residence time may contribute to the accumulation of different types of pollutants (Dugan et al. 2017). Therefore, although lakes represent 3% of the continental land surface (Verpoorter et al. 2014), extended trends in lakes are often early warning signs of significant changes (Dugan et al. 2017). Sediments from these aquatic environments constitute an excellent target because they represent the most important reservoir of pollutants (Gagnon and Fisher 1997; Culotta et al. 2006; Abdollahi et al. 2013; Li and Cai 2015), and they are CSIRO PUBLISHING Marine and Freshwater Research https://doi.org/10.1071/MF18310 Journal compilation Ó CSIRO 2019 www.publish.csiro.au/journals/mfr