39 



measurement that can be reliably achieved within specified limits of precision and accuracy 

 during routine laboratory operating conditions for a sample of a particular matrix. 



Results of the PAH analyses for the New London reference areas showed generally 

 low levels of the organic compounds (Table 3-3). Levels of low molecular weight (LMW) 

 PAHs were higher at the WREF and NE-REF areas in comparison to NLON-REF. Of the 

 LMW PAHs, phenanthrene was the most abundant. Concentrations of phenanthrene ranged 

 from 23 ppb to 87 ppb with average concentrations at the reference areas of 47 ppb (WREF), 

 43 ppb (NLON REF), and 72 ppb (NE-REF). Fluorene, acenaphthene, and acenaphthylene 

 were generally below the method detection limit at all three reference areas. 



In general, concentrations of high molecular weight (HMW) PAHs were greatest at 

 NE-REF followed by WREF and NLON-REF. The HMW PAHs dibenzo(a,h)anthracene 

 and indeno(l,2,3-cd) pyrene were below detection limit at all of the reference areas (Table 3- 

 3). Pyrene was the most abundant HMW PAH at all reference areas with average values of 

 117 ppb (NLON REF), 158 ppb (WREF), and 188 ppb (NE-REF). Fluoranthene was also 

 higher at the WREF and NE-REF areas in comparison with NLON-REF with average values 

 of 70, 102, and 45 ppb, respectively. Of the remaining HMW PAHs, benzo(a)anthracene 

 and chrysene were detected at slightly higher concentrations than the fluoranthenes, 

 benzo(a)pyrene, and benzo(g,h,i)perylene. 



3.4 CTD and Dissolved Oxygen Sampling 



On 27 June 1991, near-bottom (approximately 1 m above the bottom) oxygen 

 concentrations ranged from 7.1 to 7.7 mg-1" 1 over the disposal site mound as well as the three 

 reference areas (Table 3-4). Surface oxygen concentrations (approximately 1 m below the 

 surface) at the disposal site and reference areas ranged from 7.1 to 7.6 mg-1" 1 . The dissolved 

 oxygen concentrations were uniformly distributed throughout the water column and similar at 

 the disposal site and reference areas. These dissolved oxygen concentrations would have 

 been limiting to benthic organism colonization or growth (Tyson and Pearson 1991). 



Monitoring Cruise at the New London Disposal Site, June 1991 



