TP8 Contaminant Bioavailability
Room 19A/B, Level 4
2:10 PM - 5:30 PM, Tuesday, 11 November 2003
Chair: Kreitinger, Joe , Driscoll, Susan ,
(309) An Examination of the Bioavailability and Toxicity of Sediment-associated PAHs at Manufactured Gas Plants.
Kane Driscoll, S.1, McArdle, M.1, Menzie, C.1, Thompson, T.2, Coleman, A.3, 1 Menzie-Cura & Associates, Inc., Chelmsford, MA, USA2 The Retec Group, Seattle, WA, USA3 EPRI, Palo Alto, CA, USA
ABSTRACT- Manufactured gas plants (MGP) have historically been located along waterways. As a result of plant activities, many MGP sites are required to clean up polycyclic aromatic hydrocarbons (PAHs) in sediments. Typically, sediment remediation goals are based on sediment quality criteria that do not specifically consider the bioavailability of the specific forms of PAHs that are present at MGP sites. While sediment quality criteria based on measurement of PAHs in bulk sediment are useful for screening out areas of a site that are unlikely to be toxic, the presence of weathered NAPLs, old oil pockets, coke, or other similar fractions can trigger expensive clean-up actions without consideration of risk. This research uses recent advances in theories of PAH toxicity and field collection methods to address this concern. EPA has recently developed draft equilibrium partitioning sediment benchmarks (ESBs) for PAH mixtures for the protection of benthic (bottom-dwelling) aquatic invertebrate organisms. The EqP approach acknowledges that the toxicity of hydrophobic organic contaminants in sediment may be more closely related to the concentration of PAHs in pore water, than to the concentration in bulk sediment. Preliminary research shows that the EqP approach can be used to conservatively predict the concentrations of PAHs in sediments at MGP sites that are unlikely to contribute to toxicity to benthic invertebrates. The goal of this research is to develop a database that provides additional support for the use of the EqP approach and demonstrates why this approach is particularly appropriate for use at MGP sites. The data collected from MGP sites includes: 1) concentration of 34 PAHs in bulk sediments and pore water, 2) concentrations of total organic carbon and soot carbon in sediment, 3) toxicity in a 28-day sediment toxicity test, and 4) uptake of PAHs in a 14-day sediment bioaccumulation test. The data is used to examine the ability of ESBs for PAH mixtures to predict toxicity (or lack of toxicity) at MGP sites. The data is also used to examine whether additional measurements, such as concentrations of soot carbon in sediment and PAHs in pore water, provide a useful basis for explaining reduced bioavailability and toxicity of PAHs at MGP sites.
Key words: soot , sediment, pore water, PAHs