47 



24 m (400 m east of center). The south-to-north survey lane showed that water depth 

 increased steadily from 24 (400 m south of the center) to 30 m (400 m north of the center). 

 Water depth remained constant for the 800 m survey lane running east-to-west through the 

 center of EAST; however, depth increased from 25 m (400 m north of center) to 30 m 

 (400 m south of center). Although not level, the topography of SOUTH and EAST did not 

 exclude these areas as potential replacement reference areas. 



3.3.3 Sediment Analysis 



Grain Size. The results of sediment grain size analyses for samples collected during 

 the June 1992 WLIS survey at the two proposed reference stations are presented with the 

 June 1991 reference station results (Table 3-1). Sediment collected from the SOUTH station 

 was comparable to sediment collected from 2000S during the 1991 survey. All of the 

 fractions were within 3% of each other except for the percentage of fine sand. Station 2000S 

 in the 1991 survey contained more fine sand (45%) than the SOUTH station (38%). The 

 total fine-grained percentage (silt + clay) was 46% for SOUTH and 42% for 2000S. 



Sediment at the EAST station was described as dark grey silty clay with sand. The 

 WLIS-REF station (1991) also contained dark grey clay and silt, but with a reduced sand 

 content (Table 3-1). The fme sand content of the EAST station was more than twice that of 

 the WLIS-REF station (15% vs. 7%), although WLIS-REF had a slightly higher medium 

 sand fraction (6% vs. 2% for EAST). The fine-grained fraction was similar for both EAST 

 (83%) and WLIS-REF (85%). 



Total Organic Carbon. Total organic carbon was higher in both of the 1992 stations 

 relative to the comparable reference stations from 1991. The averaged TOC content for the 

 three SOUTH station replicates was 1.1%, compared to 0.6% for 2000S (Table 3-1). The 

 averaged TOC content for the EAST station was 1.6%, compared to 1.0% for WLIS-REF 

 (Table 3-1). , 



Metals. A suite of trace metals, Al, and Fe were measured in samples collected from 

 the SOUTH and EAST stations (Table 3-2a). Aluminum and Fe are common constituents of 

 clay minerals, and were measured for the purpose of normalizing trace metal concentrations. 

 Normalization to a reference element helps to determine what fraction of the metal 

 concentration is derived from anthropogenic sources, as opposed to naturally occurring 

 concentrations present in clay minerals. 



All of the metals measured were detected in the six WLIS samples except for Cd, 

 which was below detection in all samples (Table 3-2a). Replicate variability, expressed as 

 one standard deviation as a percent of the mean, ranged from 9 to 22%. Considering that 

 the three samples were taken from three separate grab samples, the low variability suggests 

 relatively uniform metals concentrations in each area sampled. Normalization of metals to 



Monitoring Cruise at the Western Long Island Sound Disposal Site, July 1992 



