Perfluoroalkyl substances: a risk for the aquatifc environment? A 1-year case study in river waters of central Italy.

Perfluoroalkyl substances (PFASs) are a large class of persistent emerging pollutants, ubiquitous in different environmental compartments. In this study, twenty-one PFASs were determined in seventy-eight water samples collected from six different rivers in the Umbria region (central Italy) during a 13-month monitoring campaign. The sum of the twenty-one target analytes (ΣPFASs) ranged from 2.0 to 68.5 ng L, with a mean value of 22.0 ng L. The highest concentrations of ΣPFASs were recorded in the warmest months (from June to September) due to reduced river streamflow caused by low rainfall and high temperatures. PFASs with a number of carbon atoms between four and nine prevail over C10-C18 congeners due to their higher water solubility and to their increased use in industry. PFBA, followed by PFPeA, PFHxA, and PFOA, was the most abundant congeners detected in the analyzed river water samples. Finally, the calculation of risk quotients (∑RQs) has allowed to assess the risk for three aquatic organisms (fish, algae, and daphnid) deriving from the exposure to PFASs. The survey showed that the risk for the three aquatic organisms during the four seasons and throughout the year was always negligible. The only exception was a low risk for fish and daphnid in GEN river considering the annual exposure.