CHEMICAL ANALYSES 



65 



Content of Radioactive Material 



The distribution of radium in the samples as given 

 by Piggott's determinations (1933) is illustrated in chart 

 5. A comparison of this chart with chart 3 shows that, in 

 general, the distribution of radium may be correlated 

 with that of organic matter. The highest amounts of ra- 

 dium found by Piggott are in samples 79 and 80--radio- 

 larian oozes from the central Pacific, which underlie the 

 paths of the equatorial currents. Although these sam- 

 ples are not notably high in organic matter, the sea bot- 

 tom underlying the equatorial currents was shown by 

 Agassiz to be high in living organisms of many kinds, 

 whereas the surface waters were found to be rich in liv- 

 ing forms. 



The most striking feature of the content of radioac- 

 tive materials of pelagic bottom sediments, as has been 

 pointed out by Joly (1908), Pettersson (1930), Piggott 

 (1933), and Kalle (1933), is its extreme order of magni- 

 tude, many times that of the average continental rocks. 

 Several theories have been advanced to explain this ac- 

 cumulation of radium in deep-sea deposits. Piggott 

 makes the statement that the chemistry involved in the 

 problem is that of uranium rather than of radium, and 

 points out that the oxides of uranium are similar in their 

 behavior to manganese and iron, in that they are insolu- 

 ble in sea water. Table 9 and charts 5 and 6 show, how- 

 ever, that the distribution of manganese dioxide and ra- 

 dium bear an inverse relation to each other. Pettersson 

 (1930) believes that the radioactive materials are there- 

 suits of submarine vulcanism and points to the greater 

 abundance of radium in layers of cores taken from the 

 deep sea in which volcanic materials are abundant, and 

 in red clays as contrasted with Globigerina oozes. As to 

 the first point it is possible, as pointed out by Piggott, 

 that the smaller amount of radioactive materials in Glo- 

 bigerina oozes is owing to a differential dilution of a 

 continuing process similar to that taking place with re- 

 spect to organic matter. It will be noted, furthermore, 

 that the siliceous oozes collected northeast of Japan which 



contain a great deal of volcanic material have only a 

 moderate radium content. Berget (1930) has suggested 

 that the radium content of marine sediments is owing to 

 organic accumulation, and data by Professor R. D. Evans 

 show that the ash of marine plants does contain moderate 

 amounts of radioactive materials. 



Distribution and Amount of Zr02 



In chart 4 the distribution of Zr02 in deep-sea de- 

 posits collected by the Carnegie is shown. Except for 

 the northwest Pacific siliceous oozes, which probably 

 originated from the decomposition of volcanic material, 

 and in which the Zr02 content is low, the distribution of 

 zirconium is similar to that of organic matter, but there 

 is no close relation between the two, and it is probable 

 that the similarity in distribution may be explained on the 

 basis that the same factors which influence the distribu- 

 tion of nitrogen influence the distribution of zirconium. 

 The contents of between one-tenth and one-fourth of 1 per 

 cent of zirconium dioxide in the Pacific clays are some- 

 what difficult to explain on the Murray theory that these 

 clays originate from the submarine decomposition of 

 volcanic debris, since zircon is not usually present in 

 such large amounts in volcanic rocks, except in certain 

 nephelite -bearing eruptives. On the other hand, zirconi- 

 um is probably concentrated in most continental soils 

 and would be expected in deep-sea clays if these were 

 formed by the deposition of fine material carried in sus- 

 pension or by the wind from land. 



Manganese, Phosphate, and Iron 



The distribution of manganese is shown in chart 6, 

 from which it may be seen that the highest amounts of 

 manganese are found in Globigerina oozes of intermedi- 

 ate carbonate content from the southeast Pacific. The 

 distribution of phosphate given in chart 7 is similar to 



Table 15. Partial chemical analyses of foraminifera from globigerina oozes in per cent 



Si02 0.52 0.08 0.72 0.56 0.48 



AI2O3 n.d. n.d. 0.22 n.d. n.d. 1.35 



FeO + Fe203 1.68 1.13 1.43 0.64 0.51 



MgO 0.16 0.10 0.12 0.14 0.15^ 



CaO 53.12 53. 82^ 53.95 53.47 54.52 54.17 



P2O5 n.d. n.d. ^ n.d. n.d. ?^ 



CO2 41.69 42.61° 43.10 41.95 42.72 42.38 



H2O - 105° n.d. n.d. 0.51^ n.d. n.d. 



Loss on ignition-C02 n.d. n.d. 0.78 n.d. n.d. 0.87 



Total 97.17 97.74 98.20 98.58 99.91 



CO2 calculated from CaO 41.70 42.25 42.35 41.97 42.80 42.52 



Abbreviation used as follows: n.d. = no determination. Analyses by Sharp-Schurtz Company, 

 Lancaster, Ohio. ^ Duplicate determination checked within 0.02 per cent. b Exact check ob- 



tained on duplicate determination. c Determined some time after the other analyses on remainder 

 of sample, which meanwhile had been kept in a tightly sealed container. °Mean of two determina- 

 tions: individual values 0.14 and 0.16 per cent. e 'A test for P2O5 indicated that some might be 

 present, but the size sample worked upon was so small that we are not quite sure of its presence," 

 communication from Sharp-Schurtz Company. 



