Screening for pharmaceuticals and pesticides in bio-based fertilizers, and their effect on degradation and crop uptake of pharmaceuticals in soil

Bio-based fertilizers (BBFs) are sustainable alternatives to mineral fertilizers but may introduce trace pharmaceuticals and pesticides into soils. Within the EU LEX4BIO project, this thesis screens contaminants in 15 BBFs and BBF-amended soils, develops an optimized modified QuEChERS method for target analysis, and applies suspect screening to broaden coverage. Manure- and plant-based BBFs often contained detectable pharmaceuticals, whereas ash-based BBFs did not; only a few compounds occurred in amended soils at low ng/g levels. Batch sorption experiments show that higher organic matter and lower pH increase sorption, while ash-based amendments reduce it; organic matter generally dominates. Using sequential CaCl2 extraction as a proxy for the bioavailable fraction (EAS), BBFs decreased EAS, increased sorption and sequestration, and prolonged persistence. Dedicated experiments decoupling pore-water degradation from sorption show that BBFs increase persistence in the aqueous and/or sorbed phases, thereby extending soil half-lives in a compound-specific manner. Greenhouse studies with wheatgrass and lettuce show that BBFs reduce plant uptake by increasing sorption and lowering SPW availability. I derive a linear model linking SPW-based bioaccumulation factors to their half-life and soil-water distribution coefficients (Kd), and introduce time-weighted SPW uptake factors (RCF'spw, BCF'spw) that track exposure dynamics and correlate with logP/logD and Kd. Overall, the integrated analytical–experimental–modeling framework clarifies how BBFs alter bioavailability, degradation, and crop exposure. Monitoring bioavailable fractions is key. The results support risk assessment and BBF management to limit transfer to food chains and motivate broader soil sets and data-driven prediction.