Notes on collection of samples 

 at sea 



Total phosphorous sample bottles "baited 

 with thorium carbonate were not rinsed at sea 

 before drawing samples . All other bottles, 

 tubes, and vials were rinsed twice with sea 

 water from the Nansen bottles before samples 

 were drawn . 



Vials and tubes containing samples for in- 

 organic phosphate, carbohydrates, proteins, 

 and nitrate -nitrite were prepared for freezing 

 by taping the junction of the cap and the tube 

 with plastic electrician's tape (to prevent con- 

 tamination of samples by ethylene glycol) . 1/ 

 They were then immersed in 38% ethylene 

 glycol freeze bath until completely frozen, 

 after which they were removed from the bath 

 and stored in a deep-freezer at 0° to -10°F 

 (Collier and Marvin 1953). 



General notes on methods 



StocK solutions of standards were prepared 

 with distilled water, and subsequent dilutions 

 made with synthetic sea water . Synthetic sea 

 water for total phosphorous, inorganic phos- 

 phate, and carbohydrate analyses was pre- 

 pared by dissolving 35 gm . sodium chloride 

 in distilled water and diluting to one liter; for 

 nitrate -nitrite, 20 ml. cone, hydrochloric 

 acid was added to distilled water and diluted 

 to one liter; and for proteins, by dissolving 

 35 gm. sodium chloride and 6.5 gm. magnes- 

 ium sulphate in distilled water and diluting to 

 one liter. 



Densities were read from scale "A" on the 

 Fisher instrument, and from the optical 

 density scale on the Beckman instrument, 

 after the instruments were adjusted to zero 

 with a distilled water blank. Density readings 

 were recorded as -log T. 



Notes on calculation of concen- 



tration values 



Standardization curves were prepared for 

 each set of standards by plotting Tog T values 

 against concentrations of standards . Those 

 for nitrate -nitrite were fitted as smooth curves 

 through all points, while all others were fitted 

 as straight lines. 



Concentration values for nitrate -nitrite 

 were determined by direct reading from 

 standardization curves. Those for total phos- 

 phorous and inorganic phosphate were calcu- 

 lated by dividing the -log T values by a factor 

 (equivalent to "the slope of the line" in the 

 standardization curves). Those for carbo- 

 hydrates and proteins were calculated by sub- 

 tracting the -log T value for the zero 

 concentration of the standard from the -log T 

 values of the samples, and then dividing by 

 the factor. 



Concentration values were calculated to the 

 nearest 0.5 of a unit for nitrate -nitrite, and 

 to the nearest 0.1 of a unit for total phosphor 

 ous, inorganic phosphate, carbohydrates, and 

 proteins. 



Chemicals used, with the exception of N- 

 ethylcarbazole, were reagent grade. A set of 

 standards was run with each batch of sea water 

 samples and treated in the same manner as the 

 samples. 



A Beckman DU Spectrophotometer was 

 used in the protein determination, and a 

 Fisher AC Electrophotometer used for total 

 phosphorous, inorganic phosphate, nitrate - 

 nitrite, and carbohydrate determinations. 



1/ Beginning with Cruise 6, samples for carbo- 

 hydrates were placed immediately in the deep 

 freeze, to eliminate all contact with ethylene 

 glycol . 



