QUANTIFYING PFAS IN THE EDWARDS AQUIFER IN SOUTH CENTRAL TEXAS

Per- and polyfluoroalkyl substances (PFAS) have received remarkable attention in the recent years as emerging contaminants. They are a family of fluorinated organic compounds with an anthropogenic origin. PFAS poses a risk to the human population and ecology due to their widespread usage in industry and tendency to bioaccumulation. It is crucial to quantify PFAS in aquifers as they may act as a potential source of these toxins to humans and the associated ecosystem. The present study focuses on the quantification of 23 species (C4 to C12) of PFAS from 12 different locations in the Edwards aquifer and surroundings in South Central Texas from March to June 2023 as well as rainwater samples collected during the same months. The analysis of PFAS is completed by using triple quadrupole liquid chromatography mass spectrometry (LC/MS-MS). The PFAS concentration in each sample varies with a mean value of 64.8ng/L for the total of 15 samples. The surface water in a rural region of the Cibolo Creek watershed contains predominately long-chain compounds, including 8:2 FTS (C8), PFDoA (C12), and PFOS (C8), whereas samples collected in urban and residential areas downstream contain 4:2 FTS (C4) and PFPeA (C5), highlighting both the mobility of short-chain compounds and the phasing out of long-chain compounds for short-chain alternatives in modern-day industries. The samples collected in Comal Springs display a dominance of NFDHA and 8:2 FTS (C8) compounds. Rainwater shows concentrations ranging from 2.3 ng/L to 23.3 ng/L in total 6 samples with the predominance of PFDA (C10), PFHpA (C7) and PFHxA (C6) compounds. Continuous monitoring the distribution and quantitative speciation of PFAS in water systems in this area, which is currently in progress, would shed light on identifying their potential sources and facilitate possible remediation in the future.