Per- and polyfluoroalkyl contaminated freshwater impacts adjacent riparian food webs

By Alina Koch, Micael Jonsson, Leo Wai-Yin Yeung, Anna Kärrman, Lutz Ahrens, Alf Ekblad, and Thanh Wang
Environ. Sci. Technol.
September 9, 2020
DOI: 10.1021/acs.est.0c01640

The occurrence of per- and polyfluoroalkyl substances (PFASs) in aquatic ecosystems is a global concern due to their persistence, potential bioaccumulation and toxicity. In this study, we investigated a PFAS-contaminated pond in Sweden to assess the cross-boundary transfer of PFASs from the aquatic environment to the riparian zone via emergent aquatic insects. Aquatic and terrestrial invertebrates, surface water, sediment, soil and plants were analysed for 24 PFASs including branched isomers. Stable isotope analysis of carbon and nitrogen was performed to elucidate the importance of diet and trophic position for PFAS uptake. We present the first evidence that PFASs can propagate to the riparian food web via aquatic emergent insects. Elevated Σ24PFAS concentrations were found in aquatic insect larvae, such as dragon- and damselflies, ranging from 1100-4600 ng g-1 dry weight (dw), and remained high in emerged adults (120-3500 ng g-1 dw), indicating exposure risks for top predators that prey in riparian zones. In terrestrial invertebrate consumers, PFAS concentrations increased with the degree of aquatic-based diet and at higher trophic levels. Furthermore, stable isotope data together with calculated bioaccumulations factors indicated that bioconcentration of PFASs was the major pathway of exposure in the aquatic food web, while implying that biomagnification occurred in the riparian food web.

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