PFAS profiles in biosolids, composts, and chemical fertilizers intended for agricultural land application in Quebec (Canada)

Biosolids, sewage sludge, and composts are applied to agricultural land for nutrient recovery and soil organic matter replenishment, aligning with sustainable development goals. However, they may contain per- and polyfluoroalkyl substances (PFAS) that can enter the food chain through plant bioaccumulation and leaching into the groundwater. This study analyzed 80 PFAS compounds in sewage sludge, biosolids, commercial composts, and chemical fertilizers in Quebec, Canada, using UHPLC-HRMS (Orbitrap Q-Exactive). PFAS concentrations ranged from 18 to 59 µg/kg in commercial composts, 9.8 to 213 µg/kg in pulp and paper sludge, 15 to 705 µg/kg in sewage sludge, 12 to 1310 µg/kg in biosolids, and 14.6 µg/kg on average in biosolids ash. Dominant PFAS classes included diPAPs, sulfonamides, PFCAs, and PFSAs. High diPAPs concentrations indicated widespread use in domestic, commercial, or industrial applications. This study also observed a negligible correlation between soil organic carbon and PFAS concentration in the biowastes signifying a stronger influence due to different WWTP configurations, the quality of the wastewater inputs and other medium's properties that could affect PFAS partitioning to the biowastes. Environmental assessments showed PFAS loads of up to 30 µg/kg soil from a single application, within some regulatory limits. However, repeated applications could lead to PFAS accumulation in soil, posing risks to crops and groundwater.