PFAS concentrations and compositional profiles in great tit (Parus major) feathers, faecal samples and blood plasma: Implications for non-invasive monitoring.

Per- and polyfluoroalkyl substances (PFAS) are widespread in our environment, and have the ability to bioaccumulate in biota. To monitor local PFAS contamination, often bioindicator species are used, of which the great tit is a frequently studied species. To be able to monitor these compounds, generally invasive sampling techniques are used (e.g. blood plasma, feathers). To this day, only a few studies have analysed PFAS in the faeces of wild birds, which were all performed on aquatic birds, and only one of these looked at the suitability of faeces samples to replace blood sampling. Therefore, the present study looked at the PFAS concentrations and compositional profiles in blood plasma, feathers and faeces of great tits and associations between these matrices, to provide novel and important information on non-invasive monitoring practises. All samples were analysed for 42 target PFAS using UPLC-MS/MS analysis. Matrix-specific differences were found in PFAS accumulation among blood plasma, feathers and faeces. Most compositional profiles were dominated by long-chained PFSAs, of which PFOS was the dominant compound, both in adults and nestlings. Furthermore, diPAPs were only detected in feather samples. Additionally, only very few associations were found among the matrices analysed, which suggests that faecal samples are not suitable to replace plasma or feather samples. On the other hand, faecal samples were proven to give valuable complementary information on the exposure of these birds to PFAS.