Per- and polyfluoroalkyl substances (PFAS) in sediments collected from the Pensacola Bay System watershed

Sediment samples from 25 locations in the Pensacola Bay System (PBS) watershed were analyzed for the presence of 51 per- and polyfluoroalkyl substances (PFAS) using ultra high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and selected reaction monitoring. Results revealed quantifiable concentrations of PFAS in all sampling locations. More specifically, perfluorobutanoic acid (PFBA) was present in every sediment sample with a minimum and maximum concentration of 0.04 to 0.48 ng g^-1 dry weight, respectively, across the 25 sites with an average of 0.1 ± 0.09 ng g^-1. While PFOS, with an average of 0.11 ± 0.14 ng g^-1 (range: -1) was the most abundant by concentration. LOQ of PFBA and PFOS were 0.01 ng g^-1 and 0.1 ng g^-1, respectively. PBS 22 site had the highest concentration of total (ΣPFAS) PFAS with 3.89 ng g^-1 and the third highest number of PFAS were detected in this location (23 out of 51 PFAS monitored). These results could be due to the proximity of this site to a paper manufacturing company. Site PBS 21, which is close to the Pensacola International Airport (PNS), had the second highest concentration of PFAS with 1.68 ng g^-1. Comparison between the ΣPFAS concentration present in sediments collected in July 2020 and sediments collected from nine repeat sites after Hurricane Sally (HS, September 2020), showed values, on average, 47% lower. These results highlight that the PBS area require further environmental monitoring and management of PFAS.