Observations at this station extended only to 17 meters, as the depth 

 of bottom was only 10 fathoms. On practically every cruise the concentra- 

 tion of inorganic phosphorus was essentially the same from surface to bottom. 

 For more than half the months, the total phosphorus was also essentially the 

 same from surface to bottom but in many cases the vertical distribution was 

 very irregular with higher values either at the surface, at 10 meters, or at 

 17 meters • 



At Station 6 on the 20-fathom line forty-three miles from shore, there 

 was still a very uniform distribution of inorganic phosphorus with depth 

 throughout the year. Except in one case values were less than 0.1 _ug-at/L 

 down to 20 meters. Below this depth there was, in about half the cases a 

 slight increase in inorganic phosphorus toward the bottom. The amount of 

 organic phosphorus varied considerably from month to month and showed no 

 consistent change with depth. 



At Station 7, eighty-four miles from shore on the UO-fathom line, the 

 inorganic phosphorus concentration showed a remarkable uniformity through the 

 16 months of study. The concentration was always less than 0.10 ^ug-at/L from 

 the surface to 5>0 meters and always showed an increase between 50 and 75 

 meters. The amount of increase toward the bottom varied considerably but 

 the average value for 75 meters was 0.27 _ug-at/L while for the 50-meter level 

 it was 0.07 >ig=at/L. 



Judging from the phosphorus distribution one would conclude that the 

 euphotic zone at this station did not extend below 50 meters. Not only 

 did the inorganic phosphorus tend to increase below this level but the 

 amount of organic phosphorus decreased except in four cases. 



The sharp increases which occurred toward the bottom at certain times, 

 as in August 1950, probably are the result of an upwelling of deeper water 

 from farther offshore. The sections of phosphorus distribution (figs. 6 and 

 7) show this as does a study of the isotherms (unpublished) „ 



At Station 8, which is located on the 100-fathom line 120 miles from 

 the shore, observations extended well into the thermocline and below the 

 euphotic zone. This station was occupied only eight times during the 16- 

 month period because of weather conditions but sufficient information was 

 obtained from these trips to make some definite conclusions. 



The concentration of inorganic phosphorus in the surface water at 

 this station was always extremelv low, less than 0.1 ^lg-at/L. This layer 

 of phosphate-poor water extended to 80 meters at all seasons of the year 

 except in the summer. During June and August the observations show an 

 increase in inorganic phosphorus with depth beginning at about UO meters. 

 During May 1950 the phosphate depleted water extended to 100 meters. 

 Between this layer of phosphate-poor water and the bottom there was a 

 rapid increase in concentration to a value that was usually between 1.1 

 and 1.2,ug-at/L. However, in November 19h9 the concentration near the 

 bottom was only 0.7 ;ug-at/L and in August 1950 it was l.h jug-at/L. 



29 



