The strontium-calcium atom ratio in carbonate-secreting marine organisms 



29 



postulated: the solubility products of calcium and strontium carbonates are about 

 the same order of magnitude, 5 x 10-', in sea water at a temperature of 20" C and a 

 salinity of 35%„ (Wattenberg and Timmermann, 1938). When marine organisms 

 die and disintegrate, there is a tendency for calcareous materials to halmyrolyze and 

 go into solution. Should strontianite (SrCOj) be present, it would dissolve slowly 

 because sea water is not saturated with respect to strontium carbonate. On the other 

 hand, the ionic strength of calcium in sea water is such that the re-solution of calcium 

 carbonate is exceedingly limited. Should celestite (SrSOJ be present in such marine 

 organisms which have a high strontium-calcium atom ratio, it would leach much more 

 readily from the calcareous matrix, as strontium sulphate is about ten times more 

 soluble than strontium and calcium carbonates. To partially substantiate this hypo- 

 thesis, the experiments of Odum (1951 a) are cited. He demonstrated that strontium 

 existed as celestite and not strontianite as previously assumed in radiolaria. It is the 

 intention of the authors to investigate this problem further and to determine the 

 actual chemical composition of the strontium compound in such marine organisms 

 as Madreporaria. 



ACKNOWLEDGEMENT 

 The authors wish to express their appreciation for assistance received from the 

 National Science Foundation. They are indebted to Professors Lawrence R. Blinks, 

 Rolf L. Bolin and Donald P. Abbott of the Hopkins Marine Station of Stanford 

 University, for co-operation with the junior author in collection and identification of 

 the California specimens; and to Professor Emery F. Swan of the University of New 

 Hampshire, for contributing the Atlantic coast specimens. They also gratefully 

 acknowledge the many invaluable suggestions received from Dr. Dlxy Lee Ray, and 

 from their colleagues of the Department of Oceanography, University of Washington. 



Table I. — Chemical composition of calcareous portions of carbonate-secreting 



marine organisms 



* The California specimens of algae were identified by Dr. G. J. Hollenberc. 

 t The Foraminifera specimens were collected by Professor Donald Abbott and were identified 

 y Mr. Frank Sullivan. 



