area of the Western Long Island Sound Disposal Site. Therefore, 

 the lead concentrations on the WLIS-A disposal mound are somewhat 

 elevated over those of other sediments in the vicinity. 



Greig et al. (1977) also measured the concentrations of 

 nickel, chromium, mercury, and cadmium (Table 4-2). They 

 measured nickel concentrations between 22.0 and 2 2.6 ppm in the 

 vicinity of the disposal site. These are similar to the values 

 measured for both sites of the present study. The chromium 

 concentrations that Greig et al . (1977) reported were 159-164 ppm 

 which were higher than the levels measured at both the WLIS-A and 

 Reference stations in this study. The mercury concentrations 

 that they reported were 0.5-0.6 ppm. These levels are similar to 

 those from the present study and previous studies at the Western 

 Long Island Disposal Site (SAIC, 1985) . Cadmium levels were 

 below the analytical detection limits of the Greig et al. (1977) 

 study. 



Munns et al. (in preparation) reported cadmium 

 concentrations in sediment from the Reference station of the 

 Central Long Island Sound (CLIS) Disposal Site to be near 0.3 

 ppm. This is considerably lower than the levels reported in the 

 present study. The iron concentrations were similar in both 

 studies. Munns et al . (in preparation) also measured PCB 

 concentrations. They reported levels ranging from 0.03-0.05 ppm 

 in Reference sediments. In the present study the concentrations 

 were 0.09 at the Reference site and considerably higher (0.50) on 

 the WLIS mound "A". 



4 . 4 Benthic Community 



The uniform, fine-grained, soft sediments at the WLIS 

 Reference station limits the number of species present. The 

 Nucula - Nephtys assemblage present there is comprised 

 predominately of deposit-feeders. Conversely, the heterogeneity 

 of sediment types (sand mixed with mud) in the disposal site 

 allows different lifeforms and feeding types to become 

 established. Species requiring solid surfaces for attachment 

 (e.g. , the polychaete Sabellaria . the gastropod Crepidula ) , tube 

 dwellers or burrowers requiring silty sand or sandy substrate 

 (e.g., the polychaetes Pherusa , Pectinaria , Euclymene , Ampharete ; 

 the amphipod Leptocheirus ; the bivalves Ensis , Tellina ) .and 

 deposit feeders (e.g., Euclymene , Ampharete . Mediomastus and 

 Tharyx acutus ) all occur at the WLIS-A station. In large part, 

 this sediment type difference accounts for the greater species 

 richness in the survey area relative to the Reference station. 



The disposal mound station is dominated by surface- 

 dwelling deposit feeders ( Mediomastus makes up 52% of all 

 individuals counted) . This corresponds to the REMOTS® analysis 

 which indicates that the station closest to the center of mound 



15 



