4.3 Sediment Characteristics 



Sediment chemical analyses were previously conducted at 

 the WLIS-A disposal mound during June 1984 (SAIC, 1985) and 

 August and October 1985 (SAIC, 1986b) . The October sampling and 

 analysis was done to determine the effects of Hurricane Gloria. 

 The Reference station was previously sampled during June 1984 and 

 August 1985. 



Comparison of the chemical concentrations measured in 

 the Top core sections with those measured in the Bottom sections 

 revealed that certain elements did exhibit higher concentrations 

 in the Top core sections. For the samples from the WLIS-A and 

 the Reference stations, lead, copper, nickel, and oil and grease 

 were significantly higher (p<0.05) in the Top core sections. In 

 addition, chromium was also significantly higher (p<0.05) in the 

 Top sections at the Reference station. The reason for the 

 elevated concentrations of those particular elements is not 

 readily discernible at the present time. More intense sampling 

 would be needed to accurately determine the actual relationships 

 of the metal concentrations in the sediment. 



When the sediment chemistry from previous samplings at 

 the Reference station are compared to the results of the present 

 sampling there (Table 3-1) , the following can be concluded. The 

 concentrations of most parameters measured in the present study 

 are similar to those previously measured at this station. 

 Exceptions to this were mercury and PCB's which showed 

 significantly higher concentrations in the present survey and the 

 Chemical Oxygen Demand which was lower. 



At the WLIS-A mound the measured concentrations 

 reported in Table 3-1 are again generally very similar to what 

 has been previously reported (SAIC, 1985, 1986b) . However, the 

 concentrations of mercury, lead, chemical oxygen demand, and PCBs 

 are significantly higher than the previously reported values. 



Other studies have reported the concentrations of 

 metals and PCBs in Long Island Sound sediments (Table 4-2) . 

 Benninger et al. (1979) measured the concentrations of lead, 

 zinc, and copper in a sediment core collected in Central Long 

 Island Sound. The zinc concentrations that they found ranged 

 from 106-190 ppm in the top 10 cm of the sediment core. These 

 values are very similar to the concentrations at both stations in 

 the present study. The copper concentrations reported by 

 Benninger et al. (1979) ranged from 44-96 ppm, again similar to 

 the results reported here. Lead concentrations were 30-52 ppm. 

 These levels are similar to the Reference site concentrations but 

 lower than the levels reported at the WLIS-A mound (Table 3-1) . 

 Similar levels were also reported by Greig et al. (1977) in the 



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