Accumulation of Perfluorinated Compounds to Radish – a Hierarchical Model Approach

Biogas plant digestates (BPD) can be used as fertilizers. BPDs may contain organic pollutants, which may accumulate in soil and in food chain. We developed a Bayesian hierarchical model to predict the increase in concentration of perfluorinated compounds (PFC) in agricultural soil and, consequently, in radish after a single addition of BPD in soil. Bioconcentration factors (BCF) for PFCs from soil to radish were estimated in a pot experiment. The model quantifies uncertain variability in concentrations of PFCs in BPDs and uncertainty in BCF for radish.

The predicted median increase in concentration of PFOS in radish after a single addition of digestate to agricultural land described in this paper (0.02 ng/kg f.w.) was 1/200 of the concentration of PFOS in vegetables in Sweden (4.1 ng/kg), while the predicted concentration of PFOA (0.01 ng/kg f.w.) was 1/2200 of the concentrations in vegetables in Sweden (22 ng/kg). The 97.5th percentiles of the estimates reported in this paper for PFOS and PFOA, respectively, were 1/9 and 1/200 of the concentrations in vegetables in Sweden.