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Reconstructing Temporal PFAS Trends from a Sediment Core with Targeted and Nontargeted Analysis
Citation:
Cashman, M., A. Robuck, M. Morales-Mcdevitt, J. Koelmel, T. Boving, AND M. Cantwell. Reconstructing Temporal PFAS Trends from a Sediment Core with Targeted and Nontargeted Analysis. SETAC North America, 43rd Annual Meeting, Pittsburgh, PA, November 13 - 17, 2022.
Impact/Purpose:
It can be very difficult to determine sources of PFAS in the environment. Through the use of a radiometrically dated sediment core, we were able to develop an age-depth model to highlight a depositional timeline of PFAS in an urban river. This technique highlights the temporal variation of PFAS used over the past seven decades. Advanced techniques including oxidation assays, extractable organic fluorine, and nontarget analysis are also used to better constrain different types of PFAS present in the environment. Through a combination of techniques, we were able to determine many legacy PFAS that are rarely reported in the environment, largely due to a lack of analytical standards. These results will be communicated at a scientific confrence to highlight the benefit of using nontarget analysis on sediment cores for PFAS characterization.
Description:
Use of Per- and polyfluoroalkyl substances (PFAS) in commercial and consumer products predates techniques for their identification in environmental matrices. One approach to determine past PFAS releases to the environment is through examining radiometrically dated sediment cores. In this study, a sediment core was collected from the Pawtuxet River in Rhode Island, USA. The dated sediment core was analyzed for PFAS to develop an age-depth model of PFAS deposition. The coring site was a depositional area near former textile mills suspected to have used PFAS containing products. Initial targeted analysis showed 18 unique PFAS compounds in the core with long-chain perfluoroalkyl carboxylic acids (PFCAs) dominating the core profile. Peak ∑PFAS concentrations of 55 ng/g were seen in 1973. A modified total oxidizable precursor (TOP) assay and extractable organic fluorine (EOF) extraction indicated fluorine detected through targeted analysis accounted for <6% of fluorine detected in EOF, with peak fluorine detections occurring at 1976 and at the core surface (2021). Data from nontargeted liquid chromatography high-resolution mass spectrometry analysis were evaluated using FluoroMatch software. Over 20 additional PFAS compounds, including unsaturated and H-substituted PFCAs were determined. The additional compounds identified in nontarget analysis explain the unaccounted fluorine from EOF and further constrain temporal releases and distribution of PFAS from former manufacturing facilities. Ongoing research uses these data to track the transport of contaminated sediments from legacy sites in the aquatic environment.
