G48 



DATA OF GEOCHEMISTRY 



differences in the cobalt contents of their separate 

 regions. Most major rivers of North America (Durum, 

 written communication, 1960) usuaUy contain no 

 detectable cobalt, but a few samples contain 5 or 

 more ppb. The mean content for 30 samples is 

 0.89 ppb. 



For nickel there are more data, and some of these, 

 together with a summary of the information about 

 cobalt, are presented in table 90. Hutchinson (1957, 

 p. 824-825) has suggested that the single high value 

 of Braidech and Emery is due to contamination and 

 that the normal range of nickel content is from to 

 10 ppb with a mean of 5 ppb. Taking the new data 

 for rivers of North America into account, it is likely 

 that the global mean is close to 10 ppb. Passamaneck's 

 analysis of water from a mining district shows that 

 some waters may have a nickel content that is an 

 order of magnitude higher. 



SILVER 



Both Braidech and Emery (1935) and Kleinkopf 

 (1955, 1960) found silver in every water sample they 

 examined for its presence. The first of these investi- 

 gations dealt with 24 water supplies in the United 

 States. It is possible that some of the silver was due 

 to contamination, although water from Lake Michigan, 

 which was tested before treatment of any kind, con- 

 tained 20 ppb of the element, a little below the mean 

 of 28 ppb for all of the waters examined. The range 

 was 10-200 ppb, and the ratio of silver to copper was 

 about 300 times as great as that of the accessible 

 lithosphere (Hutchinson, 1957, p. 828). Kleinkopf 

 found much lower figures, his range being 0.01-3.50 



ppb for 440 waters with a mean of 0.094. His Ag/Cu 

 ratio was only about 10 times as great as that of the 

 lithosphere and seems less anomalous, the chemical 

 shmlarity of the two elements being great enough to 

 suggest that they should behave similarly in the 

 hydrosphere. Thirty-one samples of river water col- 

 lected by the International Association of Hydrology 

 in North America and Norway contained as much as 

 1.0 ppb silver with a mean of 0.16 (W. H. Durum, 

 written communication, 1960). The samples had a 

 Ag/Cu ratio similar to those of Kleinkopf. 



zinc 



Zinc contents approaching 1 ppm in lakes and rivers 

 have been reported. Kemmerer, Bovard, and Boorman 

 (1923) found 650 ppb in Bear Lake, Idaho; Braidech 

 and Emery (1935) found amounts between 200 and 300 

 ppb in water from Lake Michigan; and 200 ppb of 

 zinc has been found in the Orogodo River, Nigeria 

 (table 65). Most waters, however, contain much less 

 than this. Braidech and Emery's figures ranged from 

 the high figure for Lake Michigan down to 5 ppb. 

 Kleinkopf (1955, 1960) found between 0.25 and 34.0 

 ppb in 440 lake waters of Maine, with a mean of 2.50 

 ppb. Morita (1950) found a variation of between 0.2 

 and 1.3 with a mean of 0.6 ppb in one water from Japan 

 over a period of 2 years, and a somewhat wider range 

 of figures in a series of lakes — those from mountains 

 ranged from 1.3 to 5 ppb, whereas those from lowlands 

 ranged from 5.6 to 18 ppb. Katanuma-ko, with its 

 very acid water, contained 79 ppb of zinc. Sugihara 

 (table 47) found between 10 and 56 ppb in six river and 

 irrigation waters in Japan with a mean of 36 ppb. 

 Five hundred and thirty-six waters from California 

 (Calif. Dept. Water Resources, 1957) contained to 

 320 ppb with a mean of 6.7, and the river waters of the 

 U.S.S.R. average 45 ppb (Konovalov, 1959). The 

 mean content of ordinary lake and river water appears 

 to be about 10 ppb of total zinc. There is little direct 

 evidence concerning the state of zinc in natural waters. 

 Murata (1952) and Kimura, Fujiwara, and Nagashi 

 (1951) found it to be less easily lost from solution in 

 natural waters than copper, but the only study in which 

 an attempt was made to separate dissolved from 

 particulate forms of the element appears to be that of 

 Heide and Singer (1954), who found that the Saale at 

 Goschwitz contained, over a period of 12 months, an 

 average of 178 ppb dissolved zinc and 47 ppb in suspen- 

 sion. Excluding a single figure of 3,500 ppb dissolved 

 zinc which was the direct result of industrial pollution, 

 they found a range from 54 to 205 ppb dissolved and 

 8 to 23 ppb particulate zinc for seven stations on the 

 Saale. Zinc was strongly adsorbed by the sediment 

 and precipitated from the river water in this way. 



