Oceanographic Institution. The method is that 

 of Ketchum, Corwin, and Keen (1955). Similar 

 measurements, now available for selected 

 samples taken on Expedition SCOT (TO-58-1) 

 are given in Appendix 2. 



Nitrate, nitrite, and silicate 



Concentrations were determined, at sea, for 

 selected Nansen bottle water samples on 

 cruise TO-59-2 only (see table 3, stations T, 

 5, 16, 20, 34, 38, 46, 49, 68, 78). The methods 

 were described by Strickland (1958). Nitrate 

 was measured by reduction to nitrite with 

 hydrazine; nitrite was measured by diazotiza- 

 tion with sulfanilamide followed by coupling 

 to N(l-naphthyl)ethylene diamine; and silicate 

 was measured by forming the silicomolybdate 

 complex followed by reduction with metol- 

 oxalic acid solution. All determinations of the 

 resulting colored products were made with 

 the Beckman DU spectrophotometer. To cali- 

 brate these methods, a set of standard solutions 

 containing known amounts of nitrate, nitrite, 

 and silicate was processed with each set of 

 samples. Reagent blanks were run with each 

 set, and all samples were analyzed in duplicate. 



Analyses for nitrite and silicate were highly 

 satisfactory: duplicate determinations always 

 fell within + 5 percent of a mean value, and 

 the slope of the calibration curve was constant 

 within +5 percent from station to station. 

 Analyses for nitrate were less satisfactory: 

 duplicates sometimes did not agree to within 

 +5 percent of a mean value, in which case the 

 results were rejected. The slope of the nitrate 

 calibration curve varied greatly from station 

 to station, probably because of the motion of 

 the ship. Variations in reagent blanks would 

 result in errors of ±0. 1 fig.at./l. for nitrate, 

 +0.02 /zg.at./l. for nitrite, and j;0.05 ^g.at./l. 

 for silicate. 



Incident solar radiation 



A gimbals-mounted Eppley 10-junction 

 pyrheliometer was mounted above all super- 

 structure on the ship. The signal was recorded 

 with a 0-10 mv. Speedomax recorder. The 

 daily curve was integrated with a planimeter. 

 The daily incident radiation total is given for 

 the regular forenoon station of the day, if 



there was one, otherwise for some other 

 station occupied during the day. 



Submarine daylight 



Photometer lowerings were made at regular 

 forenoon stations between the hours of 1200 and 

 1400 local time. Methods of collecting and 

 processing the data were the same as those 

 described by Holmes and Blackburn (1960). 



Chlorophyll^ standing crop 



Water samples were collected in Van Dorn- 

 type plastic samplers and filtered, extracted, 

 and analyzed spectrophotometrically for 

 chlorophyll a_ as described by Holmes and 

 Blackburn (1960). The integrated chlorophyll ji 

 value for the sampled water column was 

 obtained by integration of smoothed profiles 

 with a polar planimeter. 



Primary production (photosynthesis) 



The following information refers to data 

 from Expedition SCOT (TO-58-1) as well as 

 those from the three later cruises; the SCOT 

 data, not previously published, are given in 

 Appendix 1. 



The carbon-14 method was employed in these 

 studies to determine the rate of carbon fixation 

 by the phytoplankton. The C* 4 solution was 

 prepared and standardized in the manner 

 described by Steemann Nielsen (1952) with the 

 exception that glass-redistilled water rather 

 than artificial sea water was used as the 

 solvent. The C 14 solution was then filtered 

 through an HA Millipore filter and put in 

 10-ml. glass ampules which were immediately 

 autoclaved. It was added with a plastic syringe 

 and stainless steel needle provided with a posi- 

 tive stop. The radioactivity of the samples 

 was measured using Geiger-Muller gas, a 

 Nuclear-Chicago Automatic Sample Changer 

 (Model C-110B) and a Nuclear-Chicago Scaler 

 (Model 182A). At least 1,280 disintegrations 

 were counted from each sample. 



All the Pyrex bottles used for incubation 

 in these studies were aged in sea water and 

 after use were washed with a detergent followed 

 by an acid (HC1) and sea-water rinse. 



