NSWC/WOL/TR 75-3 5 



Sampling can be accomplished by either manual or automatic 

 means, again depending on the purpose or analysis and method of 

 sampling. A grab sample is usually collected manually. When it 

 is necessary to extend sampling over a considerable period of time, 

 or when a continuous (repetitive) record of analysis at a given 

 sampling point is required, automatic sampling equipment is commonly 

 used. 



The maintenance of a complete record regarding the source of 

 the sample and the condition under which it has been collected is an 

 inherent part of a good sampling program. This is of particular 

 importance in field or river surveys, where a great number of samples 

 are collected from different sources and under variable conditions. 

 The U.S. Geological Survey has defined the minimum data required for 

 samples of surface waters as follows^: 



Name of water body 



Location of station or site 



Point of collection 



Date of collection 



Time of collection 



Temperature of the water 



Name of collector 



Weather and other natural or other man-made 



factors that may assist in interpreting the 



chemical quality 



3.1.2 Sampling Techniques 



Various techniques have been developed by oceanographers for 

 sampling waters of the seas at various depths. These include, for 

 example, the Nansen bottle, the Niskin bottle, and the Van Dorn 

 Sample (described in 3.1.3). However, sampling of the sub-surface 

 water affected by an explosion would require accurate placement and 

 control of sampling devices and would also involve an appreciable 

 number of stations to insure success. In addition, it would be 

 necessary to employ a sensitive tracer to provide assurance that a 

 sample was, in reality, affected by the explosion. 



Several types of tracers have been used during the past for 

 monitoring purposes. Chemical tracers, such as lithium chloride and 



4 U.S. Department of Public Works, Public Work 85, 1954, 



15 



