Establishing Toxicity Fingerprints for Manufactured Gas Plant Residuals in Sediment

摘要

Investigations of water bodies adjacent to former manufactured gas plants (MGPs) have shown elevated levels of polycyclic aromatic hydrocarbons (PAHs) in sediment. PAHs are major constituents in MGP residuals; however, PAHs are also present in a wide variety of petrogenic and pyrogenic sources. They are a variety of methods available to assess sediment quality with respect to PAHs. Most of these methods are based on associations between concentrations of PAHs and sediment toxicity at sites contaminated with chemicals other than PAHs. USEPA recently developed a model based on aquatic toxicity and chemical partitioning data and validated with spiked sediment data. The available sediment chemistry and toxicity data from sites contaminated primarily with PAHs are more consistent with this equilibrium-partitioning model than with published, association-based guidelines. USEPA’s equilibrium partitioning guidelines are designed to evaluate measured concentrations of 37 PAHs, including alkylated PAHs. Adjustment factors are applied if fewer PAHs are measured. The guidelines specify default adjustment factors; however, site-specific adjustment factors can provide a more efficient and accurate assessment. The effect of product type on the calculation of an appropriate adjustment factor is evaluated based on data from multiple analyses of various MGP residuals. The PAH toxicity fingerprints of coal tars, carbonated water gas tars, oil gas tars, and creosotes are presented. Comparing the toxicity fingerprints to various petrogenic and pyrogenic sources, such as gasoline, light and heavy fuel oil, crude oil, and urban runoff, assesses the relative potency of MGP residuals. Sediment concentrations protective of