toxic samples by factors of 6.5, 2.8, and 5.4, respectively. In addition, the average concentrations of the 

 dioxin TEQs and the total cumulative TEQs in the toxic samples exceeded the guideline value of 100 

 pg/g by factors of 3.5 and 4.2, respectively. 



Table 33. Average concentrations (pg/g, dry wt.) of 2,3,7,8-tcdd and total cumulative dioxin TEQs 

 in highly toxic (<80% survival) and nontoxic samples from Newark Bay, ratios between the aver- 

 ages, and ratios between the highly toxic averages and the respective SQG*. 



*SQG = 100 pg/g (U.S. EPA, 1993) 



The average concentrations of pesticides and total PCBs in the toxic and nontoxic samples are com- 

 pared in Table 34. The average concentrations of nearly all of these compounds were higher in the 

 toxic samples than in the nontoxic samples. The ratios of the averages ranged from 0.9 to 6.2. The 

 concentrations of some chlordane isomers, hexachlorobenzene, and the sum of the PCB congeners 

 were elevated to the greatest degree (>5.0X) in the toxic samples. Sediment guidelines were not avail- 

 able for most compounds. Among those substances for which guidelines exist, the average concentra- 

 tions in the toxic samples often were lower than the guidelines. However, the concentrations of p,p'- 

 DDE and total PCB congeners were highly elevated relative to the ERM values (Long et al., 1995). 

 Also, the average concentration of total PCBs (758 ng/g) in the toxic samples exceeded the SEC (562 

 ng/g) calculated by Mac Donald (1994). However, the average concentration of total DDTs in the toxic 

 samples (5.8 wg/goc) was far lower than the toxicity threshold (300 wg/goc) identified by Swartz et al. 

 (1994) for the amphipod R. abronius. 



Table 34. Average concentrations (ng/g, dry wt.) of pesticides and PCBs in highly toxic (<80% 

 survival) and nontoxic samples from Newark Bay, ratios between the averages, and ratios be- 

 tween the highly toxic averages and the respective SQGs. 



108 



