Modelling bioaccumulation of semi-volatile organic compounds (SOCs) from air in plants based on allometric principles

A model was developed for gaseous plant–air exchange of semi-volatile organic compounds. Based on previous soil–plant modelling, uptake and elimination kinetics were scaled as a function of plant mass and octanol–air partition ratios. Exchange of chemicals was assumed to be limited by resistances encountered during diffusion through a laminar boundary layer of air and permeation through the cuticle of the leaf. The uptake rate constant increased and the elimination rate constant decreased with the octanol–air partition ratio both apparently levelling off at high values. Differences in kinetics between species could be explained by their masses. Validation on independent data showed that bio-concentration factors of PCBs, chlorobenzenes and other chemicals were predicted well by the model. For pesticides, polycyclic aromatic hydrocarbons and dioxins deviations occurred.