16 



Atomic Radiation and Oceanography and Fisheries 



than the amount at the next lower level, de- 

 pending on the rates of turnover of the popula- 

 tions involved. 



In addition to the abundant elements carbon, 

 oxygen and hydrogen, the bodies of organisms 

 contain a number of elements in smaller 

 amounts, such as nitrogen, phosphorus, calcium, 

 strontium, copper, zinc, and iron, which are 

 essential to the life processes. These may be ob- 

 tained by organisms above the plants in the 

 food chain either from their ingested food, or 

 by direct uptake from the sea water. Since the 

 requirements for different elements are different 

 in different kinds of organisms, the fluxes of the 



of the populations of a particular part of the 

 sea, and any quantities added will be soaked up 

 by the biosphere very rapidly. 



Both dissolved and particulate materials can 

 be taken up from the environment. Iron, for 

 example, occurs in the sea almost entirely in 

 particulate form and is used in that form by 

 diatoms. Fishes can take up ionic calcium and 

 strontium directly from the sea water. Observa- 

 tions in conjunction with weapons tests, re- 

 ported in Chapter 7 of this report, have shown 

 that particulate feeders among the zooplankton 

 ingest particles of inorganic compounds and 

 retain them. 



TABLE 6 Approximate Concentration Factors of Different Elements in Members of the Marine 



Biosphere. The Concentration Factors Are Based on a Lfve Weight Basis 



(From Krumholz, Goldberg and Boroughs, Ch. 7 of This Report) 



Concentration factors 



Concentration 



Form in in sea water 

 Element sea water (micrograms/1) 



Na Ionic 10' 



K Ionic 380,000 



Cs Ionic 0.5 



Ca Ionic 400,000 



Sr Ionic 7,000 



Zn Ionic 10 



Cu Ionic 3 



Fe Particulate 10 



Ni * Ionic 2 



Mo lonic-Particulate 10 



V ? 2 



Ti ? 1 



Cr ? 0.05 



P Ionic 70 



S Ionic 900,000 



I 50 



* Values from Laevastu and Thompson (1956). 



various elements are variable from one to an- 

 other, and at different trophic levels. 



The concentration factors of some of the im- 

 portant elements in different kinds of organ- 

 isms are tabulated in Table 6, taken from Krum- 

 holz, Goldberg and Boroughs (Chapter 7 of 

 this report). Certain elements, for example, 

 sodium, occur in some organisms at lower con- 

 centrations than in the water; they are selected 

 against. On the contrary, those elements, such 

 as phosphorus, that are essential to the organ- 

 isms but occur in low concentration in the sea 

 water, are concentrated by several orders of 

 magnitude. In some parts of the sea, the phos- 

 phorus may be nearly completely removed from 

 the water by the organisms. Such elements are 

 often limiting constituents for further increase 



The uptakes of various elements by organ- 

 isms are not entirely independent of one an- 

 other. Elements of similar chemical properties 

 tend to be taken up together very roughly in the 

 same proportions as they exist in the environ- 

 ment. This is true, for example, of calcium and 

 strontium. Sometimes one element has an in- 

 hibiting effect on another. There can also be 

 synergistic effects, such as the enhancement of 

 phosphorus uptake of diatoms by increased 

 concentration of nitrogen. 



Certain elements are deposited, in large part, 

 in particular organs. Perhaps the best known 

 examples are the deposition of iodine in the 

 thyroid glands of vertebrates, or the deposition 

 of calcium and strontium in the bones of verte- 



