An Integrated Case Study for Evaluating the Impacts of an Oil Refinery Effluent on Aquatic Biota in the Delaware River: Sediment Quality Triad Studies

Abstract

ABSTRACT Triad studies consisting of chemical characterizations in sediment, sediment toxicity testing, and benthic community assessments were used to determine the impacts of Motiva Enterprises oil refinery effluent [primarily polynuclear aromatic hydorcarbons (PAHs)] on aquatic biota in the Delaware River. Triad studies were conducted at 15 near-field, mid-field, and far-field sites near the Refinery in the Delaware River during the spring and summer of 2001 and 2002. Fingerprinting analysis showed that Motiva-related PAHs may be present at four near-field sites. A summary of all Triad data by site for 2001 shows a strong case for contaminant-induced degradation at one near-field site in the discharge canal of the Refinery and two far-field sites as all three lines of evidence suggest impairment. Stressful conditions for benthic communities at the near-field site include elevated temperature conditions and various pesticides (Dieldrin, 4,4′-DDD and 4,4′-DDT). Toxicity at the near-field site may also be related to the presence of pesticides exceeding sediment quality guidelines. Due to exceedances of individual Effects Range Low (ERL) guidelines for two individual PAHs, the Motiva effluent cannot be eliminated as a potential stressor at the near-field site during the summer of 2001. A summary of Triad data for the 15 Delaware River sites sampled in 2002 shows only one mid-field site where all three lines of evidence suggest impairment. Toxicity and benthic community impairment at this mid-field site may be related to PCBs and low molecular weight PAHs. Three individual PAH ERL values were exceeded at three near-field sites in 2002. The source of these PAHs is a combination of both background signature and the Motiva effluent. Multivariate analysis, using a weight of evidence approach, is used to address ecological effects of the Motiva effluent in more detail in Alden et al. (2005).