666 



ARRHENIUS 



[chap. 25 



of many of the heavy metals from sea-water to sediment. High concentrations of 

 a specific element at the ocean floor would under these conditions be expected 

 in areas with a high rate of biological extraction of this element in the surface 

 layer. Mero {op. cit.) has established a regional regularity in the elemental 

 composition of the nodules (Fig. 6), and assumes that the regional variations 



Fig. 6. Regional variation in chemical composition of manganese nodules. Regions 

 marked A are characterized by ratios Mn/Fe less than 1; B -areas conversely have 

 exceptionally high ratios Mn/Fe (ranging from 12 to 50). In areas marked C the 

 nickel and copper content of the nodules is unusually high. D denotes regions with 

 large amounts of cobalt (0.7-2.1%) in the nodules. (Mero, unpublished, modified from 

 Mero, 1960a.) 



in copper and nickel content of the nodules are controlled by the process 

 referred to above. 



Arrhenius and Korkisch (1959) have attempted to separate from each other 

 the different minerals constituting the nodules, in order to establish the details 

 of their structure and the localization of the heavy metal ions. The results 

 demonstrate (Table II) that copper and nickel are concentrated in the man- 

 ganese oxide phases. Cobalt, part of the nickel and most of the chromium are 

 distributed between these and the acid-soluble group of the non-manganese 



