Differential PFAS transfer through the terrestrial and aquatic food web to predatory spiders

The environmental persistence of Per- and polyfluoroalkyl substances (PFAS) results in prolonged exposure of organisms, which in turn leads to bioaccumulation and trophic transfer. However, if trophic transfer is studied at all, different ecosystems are generally examined in isolation. The aim of this study was therefore to unravel the PFAS transfer through a contaminated terrestrial and aquatic food web, with spiders as top predators. To this end, organisms from the aquatic and terrestrial compartments of a PFAS-contaminated ecosystem were collected and screened for 44 PFAS. The trophic position of the organisms was investigated using stable isotopes. PFAS were present in organisms from all trophic levels (primary producers, herbivores, detritivores, predators), albeit with varying total concentrations and profiles. Several PFAS magnified towards the spiders through the terrestrial food web, adding to the growing body of evidence that some PFAS have the potential to magnify, while trophic transfer was less pronounced through the aquatic food web. There was no consistent pattern in which substances magnified and which got diluted across the food chain. TFA, the smallest and most polar PFAS, showed high food chain transfer. This emphasizes that we still lack insight into the drivers of environmental PFAS distribution, uptake by organisms and transfer through food webs.