A comparison of Per and Polyfluoroalkyl-alkyl substances in aquatic macroinvertebrates from urban and non-urban streams in Victoria, Australia.

Per- and polyfluoroalkyl substances (PFAS) are widely detected in urban surface waters globally, yet their accumulation in freshwater biota from diffuse pollution remains poorly characterised. Macroinvertebrates are a key component of freshwater food webs and a major dietary pathway for PFAS transfer to higher trophic levels. We quantified PFAS concentrations and compositional profiles in macroinvertebrates collected from 13 urban and 15 non-urban streams in the greater Melbourne region, Australia, all of which lacked known PFAS point sources. Composite macroinvertebrate samples were live-picked and identified to family-level before analysis of 25 PFAS congeners. Overall, 1083 organisms were collected from 57 families. One or more congeners were detected in 89% of samples. Median total PFAS concentrations in urban macroinvertebrates were between 6- and 28.2-times higher than in non-urban macroinvertebrates, and urban organisms had significantly higher PFOS, PFOA, PFDA and PFDoDA concentrations than non-urban organisms. Long-chain congeners dominated tissue concentrations across both land uses, with urban profiles contributing emerging replacement compounds (fluorotelomer sulfonates), whereas non-urban macroinvertebrates exhibited relatively low total PFAS burdens but unexpectedly high concentrations of short-chain PFAS (PFBA). Comparisons with published data show that diffuse urban sources can generate PFAS concentrations in macroinvertebrates approaching those reported at point-source-impacted sites. These findings demonstrate that urban land use strongly influences both the magnitude and composition of PFAS accumulation in freshwater macroinvertebrates and underscore the need for monitoring frameworks that integrate multiple sampling media and consider both legacy and emerging PFAS when assessing ecological risks in freshwater ecosystems.