85 



While there are variations between metals and locations across the mound, data 

 normalized for grain size show no distinct metal signature for CDM, UDM, mound sediments 

 or the reference area. 



PAHs. Polycyclic aromatic hydrocarbons were measured in both the short cores 

 (Table 3-7) and the long cores (Table 3-8). In the short cores, several compounds were 

 reported as below the detection limit or estimated (J=below the detection limit, but a value is 

 provided as estimated by the laboratory) in all samples, including naphthalene, 2- 

 methylnaphthalene, acenaphthene, fluorene, dibenz(a,h)anthracene, and dibenzofuran (Table 

 3-7). Overall, there were fewer low molecular weight (LMW) PAHs detected than high 

 molecular weight (HMW). Values of total LMW PAHs ranged from 29-85 ug/kg, and HMW 

 PAHs ranged from 78-648 iig/kg (Table 3-7). 



In the long cores, several compounds were below the detection limit or estimated (J) in 

 all samples, including 2-methylnaphthalene, acenaphthene, fluorene, dibenz(a,h)anthracene, 

 and dibenzofuran (Table 3-8). Overall, there were fewer low molecular weight (LMW) PAHs 

 detected than high molecular weight (HMW). Values of total LMW PAHs ranged from 36-82 

 ug/kg, and HMW PAHs ranged from 162-632 ug/kg (Table 3-8). 



In the short cores, the highest LMW PAH concentration measured was 39 ug/kg 

 (phenanthrene), and the highest HMW PAH measured was 130 (ig/kg (pyrene; Table 3-7). 

 Both of these samples were collected from short core 12A (inner zone). In the long cores, the 

 maximum LMW PAH concentration was 36 ug/kg (phenanthrene in 6A [0.75-1.0 m]), and 

 the maximum HMW PAH concentration was 120 |ig/kg pyrene (in 4A [0.75-1.0 m]). 



To compare the PAH results from the Seawolf Mound to samples collected at the 

 dredge site, PAH values were averaged from samples classified as UDM and CDM collected 

 in the Thames River (Appendix E; Maguire Group 1995). As with the metals, the values 

 measured in 1992 were much higher (by an order of magnitude) than in 1990 and 1994, so 

 these data are presented separately. Five individual compounds most commonly analyzed and 

 detected were selected for comparison (fluoranthene, pyrene, benzo(a)anthracene, chrysene, 

 and phenanthrene). This comparison shows that the PAHs measured in the short and long 

 cores were higher than WEST REF, but overall less than at the pre-dredge site (Figure 3-25). 

 Note in Figure 3-19 that the 1992 data are all divided by 10 so as to appear to be on a similar 

 scale. In addition, PAH concentrations in the long core 10A decreased slightly with depth or 

 remained fairly constant in the case of pyrene and phenthracene (Figure 3-26). An increase in 

 pyrene and phenanthrene was apparent in both Cores 4A and 6A, between the 0.5 to 0.75 m 

 sample and the 0.75 to 1.0 m sample. However, the measured total PAH concentrations 



Monitoring Cruise at the New London Disposal Site, Seawolf Mound 1995 - 1998 



