While this steady increase extended from the surface down to 300 

 meters, it was considerably more pronounced above 200 meters. An 

 insignificant drop in mid-November which extended down to 300 

 meters, was followed by a return to previous levels until mid- 

 December when the summer decline set in. A slight recovery in 

 early January was superceded almost immediately by a pronounced 

 fall on 10 January 1961. This was felt at all depths from the 

 surface down to the 100 meter level. Although some recovery was 

 recorded in the upper levels during the remainder of January and 

 early February, the general trend at all depths was downward. 

 Salinities throughout the entire water column ended up the period 

 of observation in early March at considerably lower levels of 

 value than were found in May of the previous year. Here again, 

 the greatest change in salinity was observed in the waters above 

 200 meters depth. 



A comparison of the variation of salinity values with depth 

 under summer and winter conditions is presented in Figures 3 and 

 4. Both show a steady increase in salinity from surface to bottom, 

 which is more accelerated in the upper waters and which has a 

 markedly smaller range in the winter profile. The vertical range 

 in winter (20 July 1960) was only 0.16 °/oo while in summer (10 

 January 1961) it amounted to 0.85 °/oo. 



The steady, although slight, increase observed in salinity 

 values during the winter in the upper levels may be explained by 

 an increase in salt content derived from the freezing out of the 

 salt in new ice formation. Thickness of the ice at the icehole 

 increased from 7 feet in April 1960 to 11 feet in October. Simi- 

 larly, the sharp drop in salinity may be attributed to the cumula- 

 tive build-up of both water and air temperatures which occurred 

 during the latter half of December and which reached a high point 

 in early January. Increased solar radiation also probably played 

 a part. The consequent melting of some of the ice tended to dilute 

 the upper waters and cause the drop in salinity noted. Lowering 

 air temperatures during the remainder of January slowed down the 

 melting process, and this is reflected in the slight salinity 

 recovery during this period. A second high peak in minimum air 

 temperatures occurred in early February and again sent salinities 

 tumbling. 



While there is evidence of current activity which may explain 

 some of the salinity and other irregularities noted at depths of 

 50, 100, and 300 meters by the inflow of foreign water, there 

 appears to be no possibility of the introduction of dilutants 

 through run-off or surface melting. Situated at a distance of 2 

 miles from the nearest land and sealed in by ice cover during the 

 entire period of observation, run-off is an impossibility, while 

 puddling is a most rare phenomenon in the Antarctic. 



47 



