10 



Laboratory control samples in this case were standard reference materials analyzed 

 using identical procedures for samples. Accuracy for the reference materials was within the 

 control limits for the metals as well as the PAHs with the exception of fluoranthene. The 

 laboratory result for the reference material was above the acceptable range; however, this 

 high result was felt to be specific for the reference material rather than an analytical problem 

 reflected in sample results (Knowles 1992). 



2.4 CTD and Dissolved Oxygen Sampling 



Speed of sound measurements were obtained prior to and following the bathymetric 

 survey using a Seabird SEACAT SBE 19-01 CTD probe. The CTD was lowered over the 

 side and allowed to equilibrate in ambient seawater for 1-2 minutes prior to initiating the 

 cast. Near-bottom DO concentrations at the center of the active disposal site and at all of the 

 reference areas were measured on 27 June 1991 by modified Winkler titrations. 

 (Malfunctioning of the CTD at this point required DO to be measured by titration). A 

 Niskin bottle was used to obtain water samples from approximately 1 m below the surface 

 and 1 m above the bottom. A 300 ml subsample was drawn from the bottle, preserved, and 

 titrated (duplicate aliquots of 50 ml) within 12 hours using a modification of the standard 

 Winkler titration method (Strickland and Parsons 1972, Parsons et al. 1984). 



Monitoring Cruise at the New London Disposal Site, June 1991 



