An Overview of the Development, Status, and Application of Equilibrium Partitioning Sediment Benchmarks for PAH Mixtures

ABSTRACT

This article provides an overview of the development, theoretical basis, regulatory status, and application of the U.S. Environmental Protection Agency's (USEPA's) Equilibrium Partitioning Sediment Benchmarks (ESBs) for PAH mixtures. ESBs are compared to other sediment quality guidelines (SQGs) for PAHs. Data that examine the ability of the ESB approach to predict toxic effects to invertebrates are discussed. A USEPA draft methodology for the development of site-specific ESBs that takes into account the limited bioavailability of PAHs at certain sites is discussed. Research is presented that compares the ability of ESBs and site-specific ESBs to predict the toxicity of sediments collected from manufactured gas plants (MGPs). Site-specific ESBs that accounted for adsorption of PAHs onto black carbon were better predictors of the toxicity of sediments from MGP sites than ESBs that did not account for adsorption to black carbon.

Keywords:

• equilibrium partitioning
• polycyclic aromatic hydrocarbons (PAHs)
• sediment
• black carbon
• bioavailability
• manufactured gas plants.

ACKNOWLEDGMENTS

The authors acknowledge the contribution of Andrew Coleman and the Electric Power Research Institute, the sponsor of the research conducted at manufactured gas plants.

Notes

^a Effects range low (Long et al. 1995).

^b Threshold effects level (MacDonald et al. 1996).

^c Apparent effects threshold—low (PTI Environmental Services 1991).

^d Threshold 20% effect (Field et al. 2002).

^e ∑PAH model (Swartz 1999).

^f Equilibrium partitioning sediment benchmark (USEPA 2003a).