Ecological Evaluation Technical Guidance - State of New Jersey

PAH homologs listed in the equilibrium benchmark guidance (USEPA, 2003).Pore water concentrations generated from this method are then evaluated usingUSEPA’s hydrocarbon narcosis model (USEPA, 2003). The Tier 2 SPMEanalysis is especially useful when evaluating PAH-contaminated sediments inindustrialized and urban settings where the presence of black soot (soot carbon),which is known to influence PAH bioavailability, is potentially present. Thismethod was demonstrated by Hawthorne, et al. (2007) to be significantly betterthan conventional sediment chemistry tests, as well as EqP, for predicting impactto survival as determined by sediment toxicity tests using a sensitive sedimentdwellingspecies (Hyalella azteca). If Tier 2 results indicate the potential for risk,then the assessment may proceed to Tier 3 in which sediment toxicity testing isconducted in the ERA stage of the investigation (6.2.2.5).While the USEPA tiered approach discussed above is in the form of a “whitepaper,” it represents a logical, step-wise approach that the investigator may usewhen assessing ecological risk to benthic invertebrates from PAH-contaminatedsediments.As noted above, PAHs are present as diffuse anthropogenic pollutants in manywater bodies and concentrations in the low part per million (ppm) range can beexpected in urban watersheds. As such, it is imperative that background areasamples be collected when evaluating PAHs to establish an accurate range ofPAH background contaminant levels (Section 5.3.4). This information will aid indetermining if the PAHs are related to a site discharge, and may potentiallyinfluence the development of an RMD.6.4.7 Polychlorinated Biphenyls (Aroclor vs. Congener)Polychlorinated biphenyls (PCB) are two-ringed structures with a variety ofchlorination, produced originally under the trade name “Aroclor.” Aroclors aremixtures of 209 possible congeners and were produced with a range ofchlorination (e.g. Aroclor 1016 was 16% chlorine by weight, whereas Aroclor1260 was 60% chlorine by weight). PCBs may also be divided into 10 homologclasses ranging from monochlorobiphenyl to decachlorobiphenyl. Depending onthe application, a variety of Aroclor mixtures (typical mixtures were Aroclor1016, 1242, 1248, 1254, and 1260) were used and their chemical signatures arestill found within environmental media (Ashley et al., 2003 and Imamoglu andChristensen, 2002). Because of physical, chemical, and biological processes, thelower molecular weight (and less chlorinated) PCBs within the mixture are lessfrequently found compared to relatively more stable (refractory) higher molecularweight congeners (Ashley et al., 2003 and Bernhard, et al., 2001). For example,depending on when the mixture was released into the environment, some of the209 PCB congeners present in an original Aroclor mixture may have degradedand it is not uncommon for the mono, di, and tri-substituted PCBs to be lessprevalent in environmental and biological media than the more chlorinatedcongeners (Ashley et al., 2003). The weathering of the original Aroclor mixturesand congeners presents some challenges to ecological risk assessors attempting todetermine how best to assess potential risks posed by exposure to these chemicals(de Solla, et al., 2010).Ecological Evaluation Technical Guidance Document 75Version 1.2 8/29/12