basin, (3) the rate of evaporation from the surface, and (4) the tidal 

 and other currents in the waters of the basin. The flushing time (mean 

 residence time of a water particle) is highly variable among estuaries, 

 from a few days to a year or more. 



Geochemical effects : Several things can happen to radioactive 

 materials introduced into the sea as liquid wastes. They may remain 

 in solution or be precipitated out, depending on whether or not the solu- 

 bility product of the least soluble compound in seawater has been ex- 

 ceeded. Dissolved substances may also be precipitated by coprecipi- 

 tation with other elements or by sorption on organic or inorganic parti- 

 cles already present in the sea. Both particles and dissolved materials 

 may also be taken up by organisms and enter into biochemical cycles. 



Krumholz, Goldberg and Boroughs (1957) point out that the ele- 

 ments of Groups I, II, V, VI, and VII usually occur as ionic forms in 

 seawater (these include Cs, Sr, Ba, Zr, Cu, Zn, and 1) while the other 

 elements, except the rare gases, occur as solid phases (e. g. Y, Fe, 

 Co, and Ru). These authors also tabulate, from Greendale and Ballou 

 (1954), the physical states of elements following detonation of an atomic 

 bomb, which probably also indicates the physical states resulting from 

 waste products introduced into the sea. The material is reproduced 

 here in Table 1 . 



TABLE 1 



PHYSICAL STATES OF ELEMENTS IN SEAWATER 

 (from Greendale and Ballou, 1954) 



Percentage in given physical state 



Gravity effects on particulate matter in the sea will tend to re- 

 move from the seawater radio-isotopes incorporated in such particles, 

 which eventually settle to the sea bottom. In the deep sea such sedi- 

 mentation will remove radio-isotopes from the domain of harvested 

 marine organisms. In the near shore and continental shelf waters, 



14 



