97 



The Seawolf Mound core data from 1998 were consistent with the values obtained 

 from the 1990 and 1994 in-place UDM and CDM samples. The only average metal core 

 values that were higher than those calculated from the 1990/94 UDM/CDM data were Ni and 

 Zn (Table 3-10); both values were lower than the 1992 UDM averages (Ni 64.6 mg/kg and Zn 

 235.4 mg/kg). All other 1998 detected metal values were lower than those detected in the 

 1992 UDM, including 1998 samples from Core 14B and 23A (1.0-2.0 m). Normalized to the 

 fine-grained fraction, zone-averaged values were slightly lower than 1990/94 CDM values, 

 which were lower than the 1990/94 UDM values. 



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

 (Table 3-12) and the long cores (Table 3-13). For all short core samples, the following 

 compounds were reported as below the detection limit or estimated ("J") in all samples: 2- 

 methylnaphthalene, acenaphthene, fluorene, and dibenz(a,h)-anthracene (Table 3-12). 

 Values of total LMW PAHs ranged from 35-127 ug/kg, and total HMW PAHs ranged from 

 65-519 ug/kg (values below detection were included in the summed parameters at Vi the 

 detection limit). 



The mean sums of LMW PAHs (83 ug/kg) and HMW PAHs (304 ug/kg) measured 

 in the short cores were virtually the same as the values detected at the reference area, WEST 

 REF 26A (85 and 382 Ug/kg, respectively). However, there was some variation within the 

 PAH levels measured. The lowest PAH values among the short cores, with almost all PAHs 

 reported as below detection, were measured at Core 24A collected from the Seawolf Mound 

 apex near the Navy buoy location. The highest LMW PAH concentration measured, 41 

 Ug/kg (phenanthrene), and the highest HMW PAH measured, 120 |ig/kg (pyrene), were both 

 detected in short Core 20B (middle zone). Overall, the middle zone had higher mean PAH 

 values, including almost twice the concentration of total HMW PAHs (448 Ug/kg), 

 compared to the inner (240 jig/kg) and outer (225 ug/kg) zones. 



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

 all samples: acenaphthene and fluorene (Table 3-13). Again, the mean values for mound 

 cores were similar to, although generally higher than, measured values at WEST REF. High 

 molecular weight (HMW) PAHs were predominant in all cores. Values of total LMW PAHs 

 ranged from 63-21 1 ug/kg, and HMW PAHs ranged from 137-849 ug/kg (Table 3-13). In 

 the long cores, the maximum LMW PAH concentration was 58 Ug/kg (phenanthrene in 17A 

 [1.0-1.7 m]), and the maximum HMW PAH concentration was 180 Ug/kg pyrene (in both 

 17A [1.0-1.7 m] and 23A [1.0-2.0 m]). Total PAH values increased with depth in outer 



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



