44 



At the inactive MQR mound, stations 200N, 200S, 200E, and 100E had only Stage I 

 seres. Because the prevalence of Stage I organisms was higher here than at any other 

 mound, and because of the low RPD values at this area, the apparent lack of Stage III 

 organisms at these locations may indicate, according to the DAMOS tiered monitoring 

 protocol, that further monitoring and management is needed. MQR received contaminated 

 dredged material from such projects as Mill and Quinnipiac Rivers, Black Rock Harbor, and 

 New Haven Harbor between 1982 and 1983, warranting further investigation. 



Fresh dredged material has a lack of biological activity and an increased sediment 

 oxygen demand compared to the ambient sediment. This accounts for the significantly 

 shallower RPD depths for the disposal site stations versus the reference stations. Trawling 

 over the sediment surface also may result in loss of the RPD signature by removing sediment 

 at the surface. Some evidence of trawling activity is seen near longitude 72°53.5' W, 

 stations E5 and D7. Localized areas of oxidized sediment layers greater than three 

 centimeters deep were observed near CS-90-1, CLIS-87, and in the northwest corner of the 

 survey area. Deeper bioturbation by the local infaunal assemblages causes the increased 

 RPD depths in these areas. The mean apparent RPD depths on the NHAV-74 mound are 

 deeper than those at the MQR mound, but this could be attributed to the higher concentration 

 of organic matter in the MQR material. 



4.3 CLIS Reference Area Chemistry 



The three CLIS reference areas have chemical signatures consistent with this part of 

 Long Island Sound and appear to be suitable as references for monitoring the site. As a set 

 of baseline chemistry data, this report will help in monitoring any future changes in sediment 

 chemistry associated with the reference areas. Data from CLIS reference areas are compared 

 to samples analyzed previously for Cd and Zn by the NED laboratory in 1986 and 1987 

 (Table 4-1). The values have remained unchanged (Tables 3-2 and 4-1). PAH baseline 

 information at the three reference areas showed concentrations of HMW and LMW PAH 

 compounds were greatest at 2500W, and were similar at 4500E and CLIS-REF (Table 3-3). 

 The higher TOC content at 2500W may have provided additional binding sites for the metals 

 and PAHs analyzed (Table 3-1). This would explain the higher levels of metals and PAHs at 

 2500W compared to the other two reference areas. Also, 2500W is closer to shore and may 

 receive higher input rates. 



Sediment grain size commonly correlates with both metallic and organic contaminants 

 in sediments. Studies of both natural and polluted sediments have demonstrated that higher 

 concentrations of contaminants are usually associated with the fine-grained fraction (silt/clay) 

 of sediments (Forstner and Wittman 1983, Kennish 1992, Pequegnat et al. 1990). Particulate 

 and colloidal organic matter, because of its fine grain size, surface charges, high surface area 

 to volume ratio, and microbial coatings, serve to adsorb or chelate organic and metallic 



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



