48 



currently thought that pyrogenic PAHs are more tightly bound to the particles than petroleum 

 source PAHs (McGroddy et al. 1992). 



As PAHs enter water from various sources, they quickly become adsorbed onto 

 organic and inorganic particulate matter, and large amounts are deposited in bottom 

 sediments. Once in bottom sediments, PAHs may undergo biotransformation and 

 biodegradation by benthic organisms. The principal degradative processes for PAHs in the 

 marine environment are photoxidation, chemical oxidation, and biological transformation by 

 microbes and aquatic animals (Kennish 1992). 



Total LMW and HMW PAHs normalized to grain size from the CLIS reference areas 

 were higher than three of the NS&T sites (Eastern Long Island Sound, New Haven Harbor, 

 and Huntington Harbor) and lower than three sites (Housatonic River, Sheffield Island, 

 Western Long Island Sound; Table 4-2). Of the six NS&T sites, only two are not nearshore 

 sites: Eastern (ELI) and Western (WLI) Long Island Sound. The fact that the CLIS data fell 

 between these two sites is consistent with the central Long Island Sound location. 



There were a few individual PAH compound concentrations measured in CLIS 

 reference samples that were exceptions to the trend shown by the total LMW and HMW 

 values. Benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(g,h,i)perylene, all HMW 

 PAHs, had higher concentrations in CLIS samples than all of the NS&T sites. 

 Concentrations of acenaphthylene (LMW) and indeno(l,2,3-cd)pyrene (HMW) at the CLIS 

 reference areas were higher than all of the NS&T sites except for WLI (Table 4-2). 



4.4 Bottom Water Dissolved Oxygen 



Dissolved oxygen concentrations in bottom water at both the CLIS-90 buoy mound 

 and the three reference areas were comparable and high relative to the physiological 

 requirements of macrofaunal organisms (Table 4-3). The objective of the CTD/DO sampling 

 was to assess near-bottom DO concentrations relative to benthic habitat conditions within the 

 reference areas and at the active disposal point. Bottom waters, ranging from 6.3 to 

 6.77 ppm DO, were all within the aerobic range (Table 4-4). Low DO levels do not affect 

 the behavior or structure of benthic assemblages until the concentration decreases to the 

 hypoxic threshold of 2 ppm (Tyson and Pearson 1991). The absence of hypoxia means there 

 was no regionwide hypoxia effecting the area. 



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



