88 BIOLOGICAL EFFECTS OF ATOMIC RADIATION 



as tagging material only those cheap wastes that some day may be dumped at sea; neverthe- 

 less, it is most desirable to avoid all uneasiness by the use of only short-lived isotopes in the 

 early tests. Recently, small reactors have been offered for installation on research ships (or 

 shore stations), and it appears that quite adeqate amounts of Na-' ( 14 hr), Rb*"" (18 days), 

 and other short-lived isotopes can be made available to the oceanographer under suitable 

 conditions. These small reactors would serve further to improve sensitivity in the detection and 

 identification by affording means for making activation analyses. 



A remarkable dye-tagging procedure has just been announced by J. H. Carpenter (26). 

 It has been discovered that the readily available, stable, and commercial dye, Rhodamine B, 

 can be detected after dilution to the level of 2 parts in 10'- (i.e., 2x 10 ' ppb). This dye is 

 safe, and it is inexpensive (about $5 per pound). The dye is detected by use of a modification 

 of a standard fluorimeter. The technique has been used already (to dilutions of 0.05 ppb) in 

 studying wake motions and surface water movements in estuarine waters, and has proven very 

 successful even under unfavorable field conditions where much silt was present in the water. 

 It is reported that this dye is far more stable than any other previously used, and that it can 

 be expected to persist in the sea for months. Because of the sensitivity afforded, the low cost, 

 and the absence of all human hazard, it appears that this technique will be of real and im- 

 mediate use at sea either as the sole tagging agent or together with radioactive tags. Efforts 

 are now being made to develop a suitable in situ detecting instrument. 



To follow water movements in detail in the open sea, it is necessary to call upon elec- 

 tronic position-indicating equipment of a type not necessary in usual navigation. Several 

 satisfactory electronic systems for positioning a ship have been demonstrated; however, few 

 American oceanographic expeditions have yet been able to afford the large investment re- 

 quired to obtain the ship's position to the desired accuracy. This is especially true where the 

 survey includes stations several hundred miles from shore. Anchored buoys and acoustic 

 markers can also be used to solve off-shore navigation and detection problems. 



TABLE 3— EXAMPLES OF RECENT MEASUREMENTS OF LEVELS OF LONG- 

 LIVED ARTIFICIAL ACTIVITIES IN SURFACE SEA WATER 



Isotope Location Date Activity Level Reference 



1. The Effects of Atomic Radiation on Oceanography and Fisheries, NAS-NRC Pub. 551, 

 1957. 



2. Radioactive Waste Disposal into Atlantic and Gulf Coastal Waters, NAS-NRC Pub. 

 655, 1959. 



