The frequency distributions of reference and disposal site 

 station OSI values both have major modes at 11, although a 

 substantial number of lower values also were calculated (Figure 

 3-17) . This wide range of OSI values reflects both the patchy 

 distribution of Stage III organisms at individual stations, as well 

 as the relatively wide range of RPD depths resulting from the 

 presence of discontinuous patches of reduced sediment near the 

 sediment-water interface at many stations. There was no significant 

 difference in OSI values at the disposal site stations versus the 

 pooled reference site stations (Mann-Whitney U-test, p = 0.6511). 

 In both cases, the overall average OSI value was 8.0. The OSI 

 values at both the disposal and reference sites were not 

 significantly different from those calculated in the November 1987 

 REMOTS® survey (Mann-Whitney U-test, p = 0.2150 for the disposal 

 site and p = 0.5306 for the reference sites). 



3.3 CTD and Dissolved Oxygen Sampling 



The lack of linearity in the calibration curve computed 

 for the Rexnord® DO probe led to the discovery that the platinum 

 tip on the probe was partially disconnected during sampling; this 

 resulted in a wide variance in the probe's response. Without the 

 calibration curve, continuous vertical profiles of DO concentrations 

 could not be accurately calculated from probe voltages measured in 

 the field. However, near-bottom and near-surface DO concentrations 

 at selected disposal site stations and at the reference sites were 

 determined by Winkler titration. Near-bottom DO concentrations at 

 the disposal site stations ranged between 3.5 and 4.6 mg/£, while 

 those measured at the three reference sites ranged between 3.5 and 

 4.2 mg/£ (Table 3-1) . DO concentrations one meter below the surface 

 were significantly higher at all stations, ranging between 7.2 and 

 7.8 mg/£ at the disposal site and 7.6 and 10.2 mg/£ at the reference 

 sites. Mid-depth water samples taken at random stations indicated 

 that DO concentrations probably decreased steadily from surface to 

 bottom on the day of sampling. For example, at disposal site 

 station 7-Y, DO measured 3.5 mg/£ near the bottom, 5.1 mg/£ at 

 mid-depth, and 7.6 mg/£ near the surface. 



Plots of the depth gradients in temperature, salinity, 

 and density (as sigma-t) at selected disposal site and reference 

 REMOTS® stations are given in the Appendix. The plot from station 

 3-E (Figure 3-18) generally is representative of all the stations. 

 This plot indicates that at the time of sampling, the water column 

 was well-stratified, as evidenced by the distinct thermocline which 

 generally occurred at a depth of about 10 m. Temperatures ranged 

 between 21C at the surface to 16. 5C at depth. Concomitant increases 

 in salinity and density (as sigma-t) with depth suggested a 

 relatively stable stratification of the water column, making it 

 resistant to large-scale vertical mixing. 



