IOO 



DISCOVERY REPORTS 



edge, gave an average content of 142 mg. at a depth of 4000 m., so that a seasonal 

 variation is fairly evident. Similarly a variation existed in the routine line of observations 

 in 8o° W. Thus, average values in 1934 at 3500 m. between the ice-edge and about 55° S 

 were as follows: March 157 mg., September 131 mg., October 140 mg., November 

 139 mg. Fig. 28 gives the phosphate content at the deepest observations in 8o° W, the 

 depth of the samples being at least 3500 m. It will be remembered that the bottom water 

 of the Scotia Sea had a phosphate content of 160 mg. in April 1934 compared with a 

 content of 140 mg. in September and October of the same year. If we compare these 

 values with those along 8o° W in 1934 some evidence may be deduced for a penetration 

 of Scotia Sea bottom water through the Drake Passage into the eastern part of the South 

 Pacific but at present the evidence from other sources, i.e. oxygen content, suggests that 

 only a trace of Scotia Sea bottom water may penetrate westward. 



The phosphate content of Antarctic bottom water is always large but is usually less 

 than that of the warm deep water. Seasonal variation occurs and in the Scotia Sea in 

 1934 the content varied between 140 mg. and 160 mg. 



LATITUDE 6B S 

 STATION „ 



64 

 I 



ft 





SB" 



S6 | 5 „ 



MARCH 

 • SEPTEMBER 

 A OCTOBER 

 ■ NOVEMBER 



Fig. 28. Graph showing the variation of the phosphate content from south to north at the deepest 



observation (3500 m. or deeper) in 8o° W. 



In 30 W Antarctic bottom water had a content of 145 mg. in the south and 125 mg. 

 in the north of the Antarctic zone. Sub-Antarctic zone values were 140-150 mg., 

 whilst at 38 S a high content of 156 mg. was recorded in mixed bottom water. 



In 1933 very low contents were recorded for the bottom water in the eastern part of 

 the South Atlantic where only 100-105 m g- was f° un( i in the Antarctic zone, whilst 

 in 1934 and 1935 considerably higher values of 130-160 mg. were found. 



South of the western part of the South Indian Ocean the Antarctic bottom water had 

 in 1934 a content of 160 mg. decreasing to 140 mg. in the north of the Antarctic zone. 



