The driving factors of per- and polyfluorinated alkyl substance (PFAS) accumulation in selected fish species: The influence of position in river continuum, fish feed composition, and pollutant properties

Per- and polyfluorinated alkyl substances (PFASs) represent a group of highly recalcitrant micropollutants, that continuously endanger the environment. The present work describes the geographical trends of fish contamination by individual PFASs (including new compounds, e.g., Gen-X) assessed by analyzing the muscle tissues of 5 separate freshwater fish species from 10 locations on the Czech section of the Elbe River and its largest tributary, the Vltava River. The data of this study also showed that the majority of the detected PFASs consisted of long chain representatives (perfluorooctane sulfonate (PFOS), perfluorononanoic acid, perfluorodecanoic acid, and perfluoroundecanoic acid), whereas short-chain PFASs as well as other compounds such as Gen-X were detected in relatively small quantities. The maximum concentrations of the targeted 32 PFASs in fish were detected in the lower stretches of the Vltava and Elbe Rivers, reaching 289.9 ng/g dw, 140.5 ng/g dw, and 162.7 ng/g dw for chub, roach, and nase, respectively. Moreover, the relationships between the PFAS (PFOS) concentrations in fish muscle tissue and isotopic ratios (delta N-15 and delta C-13) were studied to understand the effect of feed composition and position in the river continuum as a proxy for anthropogenic activity. Redundancy analysis and variation partitioning showed that the largest part of the data variability was explained by the interaction of position in the river continuum and delta N-15 (delta C-13) of the fish. The PFAS concentrations increased downstream and were positively correlated with delta N-15 and negatively correlated with delta C-13. A detailed study at one location also demonstrated the significant relationship between delta N-15 (estimated trophic position) and PFASs (PFOS) concentrations. From the tested physicochemical properties, the molecular mass and number of fluorine substituents seem to play crucial roles in PFAS bioaccumulation. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study assessed the geographical trends of fish contamination by per- and polyfluorinated alkyl substances (PFASs) in the Czech section of the Elbe River and its tributary. Long chain PFASs were found in higher concentrations, while short-chain PFASs and Gen-X were detected in lower quantities. The study also revealed that PFAS concentrations increased downstream and were positively correlated with δ N-15 and negatively correlated with δ C-13. Additionally, molecular mass and the number of fluorine substituents were found to play crucial roles in PFAS bioaccumulation.