Establishing Toxicity Fingerprints for Manufactured Gas Plant Residuals in Sediment

摘要

Investigations of water bodies adjacent to former manufactured gas plants (MGPs) have shownrnelevated levels of polycyclic aromatic hydrocarbons (PAHs) in sediment. PAHs are majorrnconstituents in MGP residuals; however, PAHs are also present in a wide variety of petrogenic andrnpyrogenic sources. They are a variety of methods available to assess sediment quality with respectrnto PAHs. Most of these methods are based on associations between concentrations of PAHs andrnsediment toxicity at sites contaminated with chemicals other than PAHs. USEPA recentlyrndeveloped a model based on aquatic toxicity and chemical partitioning data and validated withrnspiked sediment data. The available sediment chemistry and toxicity data from sites contaminatedrnprimarily with PAHs are more consistent with this equilibrium-partitioning model than withrnpublished, association-based guidelines. USEPA’s equilibrium partitioning guidelines are designedrnto evaluate measured concentrations of 37 PAHs, including alkylated PAHs. Adjustment factors arernapplied if fewer PAHs are measured. The guidelines specify default adjustment factors; however,rnsite-specific adjustment factors can provide a more efficient and accurate assessment. The effect ofrnproduct type on the calculation of an appropriate adjustment factor is evaluated based on data fromrnmultiple analyses of various MGP residuals. The PAH toxicity fingerprints of coal tars, carbonatedrnwater gas tars, oil gas tars, and creosotes are presented. Comparing the toxicity fingerprints tornvarious petrogenic and pyrogenic sources, such as gasoline, light and heavy fuel oil, crude oil, andrnurban runoff, assesses the relative potency of MGP residuals. Sediment concentrations protective of