Modelling polycyclic aromatic hydrocarbon bioavailability in historically contaminated soils with six in-vitro chemical extractions and three earthworm ecotypes

• Published in: The Science of the total environment 2022-11, Vol.845, p.157265-157265, Article 157265
• Main Authors: Esmaeili, Atefeh, Knox, Oliver, Leech, Calvin, Hasenohr, Stefan, Juhasz, Albert, Wilson, Susan C.
• Format: Article
• Language: English
• Subjects: Amynthas sp; Eisenia fetida; Equilibrium partitioning theory; Lumbricus terrestris; Risk assessment
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.157265

Accurate prediction of organic contaminant bioavailability for risk assessment in ecological applications is hindered by limited validation on relevant bioassay species. Here, six in-vitro chemical extraction methods (butanol, non-buffered and buffered hydroxypropyl-β-cyclodextrin (HPCD, Buf-HPCD), Tenax, potassium persulfate oxidation, polyoxymethylene solid phase extraction (POM)) were tested for PAH bioaccumulation prediction in three earthworm ecotypes with dissimilar exposures, Amynthas sp., Eisenia fetida, and Lumbricus terrestris, in historically contaminated soils from manufactured gas plant (MGP) sites. Extractions were compared directly and modelled in a calculation approach using equilibrium partitioning theory (EqPT) with a novel combination of different organic carbon/octanol-water partitioning parameters (KOC and KOW). In the direct comparison approach Buf-HPCD showed the closest prediction of accumulation for burrowing Amynthas sp. and L. terrestris (within 1.5 and 3.1, respectively), but Tenax and POM showed the closest approximation for E. fetida (within 1.1 and 0.9, respectively). The optimum method for predicting PAH bioaccumulation in the calculation approach depended on earthworm species and the partitioning parameters used in equations of the four models, but overall POM, which was independent of KOC, showed the closest approximation of accumulation, within a factor of 2.5 across all species. This work effectively identifies the optimum in-vitro based approaches for PAH bioavailability prediction in earthworms as a model soil health indicator for ecological risk assessment within regulatory and remediation decision frameworks. [Display omitted] •Modelling to predict PAH bioavailability in three earthworm ecotypes in aged soils•HPCD, Tenax and POM directly provided good estimates of earthworm accumulation.•POM-modelled bioavailability was within a factor of 2.5 for all earthworm species.•Model predictions improved by considering different partitioning parameters•Soil-specific KOC values were important for Eisenia fetida bioavailable PAHs.