successfully used rather than the 100 to 300 ft com- 

 monly used. Tubing dead space may be reduced by 

 inserting stainless steel wire. Use of a pressure 

 transducer in place of the gauge adapts the satu- 

 rometer for continuous monitoring (see paper by 

 D'Aoust, this conference). In addition, a technique 

 for pre-pressurization of the saturometer to the 

 expected final reading was discussed. This aids in 

 reducing the equilibration time. 



The microgasometric method of Scholander 

 et al. (Biol. Bull. 709:328-334; 1955) was mentioned 

 as being intermediate in difficulty between the 

 saturometer and Van Slyke methods. The apparatus 

 is portable and can be used in the field; however, 

 it does not appear to have been widely used in gas 

 bubble disease research and may deserve further 

 investigation. 



The Van Slyke manometric method has been 

 widely used in conjunction with a Winkler titration 

 to report data on oxygen and nitrogen saturation. 

 It is generally agreed to require high-level compe- 

 tence to operate and is not readily portable. In 



addition, mercury is used in relatively large quan- 

 tities presenting a health-safety problem. Partici- 

 pants agreed, however, that it is a highly accurate 

 method and is useful for calibration of other 

 methods, as well as for primary data collection. 



Gas chromatography offers several advantages 

 including rapid analysis of multiple samples. It is 

 not portable and is relatively costly although it 

 was reported that Carle offers a suitable chromato- 

 graph for less than $1000 (without integration). 

 Use of electronic peak area integration greatly 

 increases accuracy and precision. A disadvantage 

 is the requirement for calibration with each use; 

 however, development of a simplified electrolytic 

 calibration is continuing and a recently developed 

 ultrasonic detector offered by Tracor is claimed to 

 eliminate external calibration for gas analysis. 



Finally, a technique of continuous monitoring 

 devices indicated that additional research in this 

 area is needed and that the capability would be 

 useful for determining the dissolved gas regime in 

 the river. 



Round Table Discussion 117 



