NSWC/WOL/TR 75-35 



Little is known about the preservation of water samples which 

 are to be analyzed for their organic content. Water samples are 

 generally either acidified to pH 1 or stored in a refrigerator. The 

 samples must be stored in glass bottles since appreciable amounts 

 of organic material can be dissolved from polyethylene. 



Changes in temperature and pressure may result in the escape of 

 certain gaseous constituents (e.g. CU , C0~, CH 4 ) or the dissolution 

 of some atmospheric gases. Polyethylene vessels should not be used 

 for storage of such samples on account of their permeability to 

 gases. Weimer 9 found that the method of sample collection and 

 storage greatly affected the reproducibility of the concentration of 

 dissolved methane. Samples stored in 250-ml, glass-stoppered reagent 

 bottles gave variable results. Because of the poor reproducibility 

 obtained with this storage method, a dissolved gas sampling bottle 

 was designed 10 to eliminate contact of the water sample with the 

 atmosphere after the initial sample collection was completed. The 

 dissolved gas sampling bottle is shown in Fig. 5. 



Water from a water sampler is added through the neck of the 

 dissolved gas sampling bottle; three bottle volumes are first allowed 

 to flush through the neck and the stopcock. The stopcock is closed, 

 allowing water to fill completely the neck of the bottle. The 

 plunger is inserted (about 0.5-1 inches into the neck) with the 

 stopcock of the bottle open to expel some of the water from the 

 exit post. The stopcock is then closed. The dissolved gas sampling 

 bottle is fitted with a Male Leur tip at the stopcock for the 

 introduction of the water sample into a gas stripping chamber. 



3.2 SEDIMENT SAMPLING 



3.2.1 General Concepts of Sediment Sampling 



The same philosophy and practice applied to water sampling 

 should also be applied to sediment sampling. However, sediment 



9 Weimer, W. C. , "Some Considerations of the Chemical Limnology of 

 Lake Mary, Vilas County, Wisconsin", M.S. Thesis, Water Chemistry 

 Program, University of Wisconsin, Madison, Wis., 1970. 



10 Weimer, W. C. and Lee, G. F., "Method for the Storage of Samples 

 for Dissolved Gas Analysis," Environ. Sci. Technol. 5_, 1136 (1971) 



25 



