Including sorption to black carbon in modeling bioaccumulation of polycyclic aromatic hydrocarbons: uncertainty analysis and comparison to field data

Model estimations of bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) have been higher than field or laboratory data. This has been explained by strong sorption to black carbon (BC). In this paper, eight previously published bioaccumulation datasets were reinterpreted in terms of additional BC sorption. Biota--Solids Accumulation Factors (BSAFs) of PAHs typically decreased by 1-2 orders of magnitude and were better in line with field data in marine, fresh water, and terrestrial ecosystems. Probabilistic BC-inclusive modeling showed that if BC content is not accurately known, uncertainty in BSAFs is 2-3 orders of magnitude (90 percentile confidence interval) due to uncertainty in the BC sorption term. When BC contents are measured, the deviation between model estimations and field measurements reduces to about a factor of 3. This implies that including routine measurements of BC contents is crucial in improving risk estimations of PAHs.