38 



3.3.3 PAHs 



Replicate PAHs at each reference area were more variable than results for the metal 

 analyses; values fell within two standard deviations of the mean (Table 3-3). Several values 

 were qualified as estimated (J values) indicating that a compound was present in a 

 concentration above the method detection limit and below the practical quantitation limit. Of 

 the low molecular weight (LMW) PAHs, phenanthrene was the most abundant at all three 

 reference areas with average values of 167 ppb at CLIS-REF, 173 ppb at 4500E, and 247 

 ppb at 2500W. The average value of naphthalene, 127 ppb, was also higher at 2500W in 

 comparison to the other two reference areas. Fluorene, acenaphthene, and acenaphthylene 

 were below detection limit at CLIS-REF and either found in low concentrations or below 

 detection limit at 4500E and 2500W reference areas. Total LMW PAH values were highest 

 at 2500W and lowest at CLIS-REF. 



High molecular weight (HMW) PAHs were detected at all the reference areas, except 

 for dibenzo(a,h)anthracene, which was below detection limits at all the reference areas, and 

 indeno(l,2,3-cd)pyrene, which was below detection limits at 4500E and CLIS-REF. 

 Concentrations were greatest for pyrene with average values of 373 ppb at CLIS-REF, 410 

 ppb at 4500E, and 607 ppb at 2500W. Fluoranthene was also detected in higher 

 concentrations relative to the other HMW PAH compounds: 257 ppb at CLIS-REF, 287 ppb 

 at 4500E, and 423 ppb at 2500W. Total values for HMW PAH compounds were greatest at 

 reference area 2500W, followed by 4500E and CLIS-REF. 



3.4 CTD and Dissolved Oxygen Sampling 



All water column measurements were made on June 18 to facilitate comparisons 

 between sampling stations. The water column overlying the three reference areas and CLIS- 

 90 buoy location had similar temperature-salinity structure with a strong midwater pycnocline 

 from 1 m (2500W-REF) to 12 meters (CLIS-REF) (see Appendix). Below the pycnocline, 

 temperature and salinity remained constant to the bottom (total depth at 2500W = 13 m, 

 4500E = 20 m, CLIS-REF = 17 m, CLIS-90 = 18 m). The 2500W REF station had a 



1.5 m thick isothermal surface layer 1°C higher in temperature than the other areas. 

 Temperature and salinity were constant below 11m. 



Dissolved oxygen profiles at 4500E-REF, CLIS-REF, 2500W-REF, and the CLIS-90 

 mound decreased from the surface to the bottom water. Dissolved oxygen below the 

 pycnocline was lower than concentrations above the pycnocline by 2 to 3 ppm. The 

 concentration of DO in bottom water ranged from 6 to 7 ppm at all stations (Table 3-4). 



Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 



