approximately one meter above the bottom. A 300 ml subsample was drawn from the bottle, 

 preserved, and titrated within 12 hours using a modification of the standard Winkler titration 

 method (Strickland and Parsons 1972, Parsons et al. 1984). The original intent of this 

 sampling was to provide an in situ check on the YSI dissolved oxygen probe. However, 

 during water-column profiling the YSI probe consistently failed at depth, and therefore only 

 the results of the Winkler titrations were reported for the bottom oxygen concentrations. 

 Surface oxygen values from the YSI probe were considered reliable because the sensor was 

 calibrated to an air-saturated standard immediately prior to deployment. These values were 

 compensated for in situ salinity using the CTD results and the algorithm of Benson and 

 Krause (1984). When comparing the surface and near-bottom DO values obtained by these 

 two methods it must be kept in mind that there was no calibration between the instruments. 



Monitoring Cruise at the New London Disposal Site, June-July 1990 



