Perfluoroalkyl substances in the Maltese environment - (I) surface water and rain water

•The occurrence and distribution of 2 perfluorosulfonates and 5 perfluorocarboxylates in the Maltese surface and rain water were investigated.•PFOA and PFOS were the most abundant PFASs in surface water.•Except for a few samples PFAS concentrations and PFAS composition in precipitation were quite uniform suggesting common sources.•Air masses from source regions yielded rain with higher ƩPFAS concentrations than ones travelling over sea or having rain events prior to sampling.

The presence of perfluoroalkyl substances (PFASs) in rain water on the Maltese Islands is reported here for the first time and an extensive survey of these substances in surface water also reported. The Maltese archipelago lies at the centre of the Mediterranean Sea and consists of three main inhabited islands: Malta, Gozo and Comino. Surface water was collected from 41 valleys during the months of February and March 2015 at the peak of the wet season. Rain water was collected during the months of December 2014, February, August, September and October 2015. PFASs were extracted from the water samples using solid phase extraction and the extracts were then analysed using ultra performance liquid chromatography coupled to mass spectrometry in tandem (UPLC-MS/MS). All surface and rain water samples were contaminated with at least one PFAS. PFOS (< LOD - 8.6 ng/L) and PFOA (ND - 16 ng/L) were the two major PFASs being detected in 100% and 95% of the surface waters respectively. The ΣPFAS concentrations in rain water ranged between 0.38 ng/L (1st October 2015) and 6 ng/L (21st February 2015). The Maltese archipelago is surrounded by sea and disconnected from any other mainland; therefore the results confirm that remote environments can become contaminated by PFASs from rain events depending on wind prevailing trajectories.

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