Plots of the depth gradients in dissolved oxygen, 

 temperature, salinity, and density (as sigma-t) at the selected 

 REMOTS stations indicated in Figure 3-15 are given in Appendix I. 

 A representative CTD/DO plot obtained on 27 July at station 

 2-400SE (Figure 3-16) indicates that the water column was 

 stratified, with evidence of a thermocline and halocline (and 

 resultant pycnocline) at a depth of 12 to 15 m. Above and below 

 this steep density gradient, the water column appears to have been 

 well-mixed, as indicated by the vertical structure of the 

 temperature, salinity, and DO data. In contrast, the 27 July 

 CTD/DO plot from station 400W (Figure 3-17) does not show strong 

 gradients in any of the measured parameters. The gradual decrease 

 in temperature and increase in salinity and density with depth 

 indicates an unstratified water column. 



On 29 July, there were wider variations in the vertical 

 distributions of temperature, salinity, and density. For example, 

 the steady decrease in temperature and gradual increase in 

 salinity and density at station 4-400NE (Figure 3-18) indicate a 

 lack of strong vertical gradients in these parameters. 

 Conversely, a complicated and stratified water column structure 

 was observed at station W-Ref (Figure 3-19) , where there was a 

 near-surface (i.e., less than 5 meters deep) thermocline, 

 halocline, and pycnocline as well as sharp gradients in 

 temperature, salinity, and density at a depth of 18-20 meters. 

 Concurrently, station NE-Ref exhibited remarkable uniformity in 

 temperature, salinity, and density throughout the water column 

 (Figure 3-20) . 



There was no notable depth gradient in dissolved oxygen 

 concentrations at any of the stations sampled on 27 July. All of 

 the plots from this day show only a slight, steady decrease in DO 

 concentrations with depth. With the exception of stations 800S 

 and 1000S, near-bottom DO concentrations measured on 29 July were 

 generally lower than those measured on the 27th. However, as on 

 27 July, DO concentrations did not exhibit marked gradients with 

 depth . 



3.4 Sediment Characteristics 



Sediments at all six stations appeared olive gray with 

 variable amounts of fine sand and silt/clay as the dominant 

 grain-size fractions (Table 3-1) . Stations CTR and 400SE 

 contained relatively higher percentages of silt and clay (69% 

 fines) , while fine-grained sand occurred in higher proportions 

 than silt at stations NLON-Ref, 800SE, 400NW and 1500NW. 



The mean concentrations of Hg, Pb, As, Cd, and Cu in 

 surface sediments at the six stations sampled (Table 3-2) were all 

 at Low levels, according to the New England River Basins 

 Commission's (NERBC) interim criteria (NERBC, 1980). While such 



