from about the middle of the bottle. A pipetteful 

 of sample water was drawn from the top of the 

 bottle and used to rinse the empty ampoule. The 

 rinse water was then returned to the middle of 

 the bottle and the pipette rinsed with water from 

 the top of the bottle. The sample bottle was then 

 stoppered. 



Use of Illuminated Water Bath 



Before placing the bottles in the water 

 bath, the tops of the opaquely coated "dark" 

 bottles were made light-tight by covering them 

 with aluminum foil. The foil was checked each 

 time for holes. 



In the water bath (fig. 5) used on 

 EASTROPIC the areas adjacent to the ends of the 

 circular fluorescent tubes, where the wires are 

 connected, were not illuminated; therefore, the 

 light bottles were not placed in these portions of 

 the chamber. This space was utilized for the 

 dark bottles. When more samples were collected 

 than would fit into the water bath, the dark bottles 

 were placed in a bucket or sink filled with circu- 

 lating sea water. 



The water bath was supplied with 

 circulating sea water in which the temperature 

 varied less than 1°F. from that of the sea sur- 

 face through which the ship was cruising. Illu- 

 mination was maintained at 1 , 500- to 1 , 800 -foot 

 candles by Westinghouse 32-watt "cool white, 

 circline, " fluorescent tubes. 



The samples were placed in the water 

 bath immediately after inoculation with the radio- 

 active carbon and remained in the water bath for 

 4 or 5 hours. During this time interval carbon 

 fixation in the sample is approximately linear 

 (Doty 1955). A longer period might be desirable, 

 however, since the larger the amount of C^'* 

 incorporated in the cells, as fixed carbon, the 

 shorter the period for counting to the desired 

 statistical accuracy. 



Filtration 



After removing the bottles from the 

 water bath, their contents were filtered through 

 15/16-inch Millipore "HA" filter discs mounted 

 in Tracerlab E-8B filter holders. Filtration of 

 an entire bottle of sample water, under suction 

 from an aspirator, required only 3-5 minutes. 

 After filtration the disc was "washed" by draw- 

 ing through it about 20 ml. of 0.001/NHCl in 

 35 percent NaCl followed by about 30 ml. of 

 filtered sea water. 



The filter holder, upon completion of the 

 filtering, was disassembled and the Millipore 

 disc placed in one of a series of numbered holes 

 cut in a circular piece of corrugated paper 

 board which was stored in a desiccator. A 

 sheet of paper glued to one side of each board 

 provided bottoms to the holes or wells in each 

 of which was stored one filter disc. 



When the moisture indicators included in 

 each desiccator showed the desiccant to be 

 reaching the limit of its effectiveness, the 

 desiccant was dried in the galley oven. Silica 

 gel was used as the desiccant; experiments have 

 demonstrated that with some other desiccants, 

 especially calcium chloride, there is a signifi- 

 cant loss of Ci'4. 



Cleaning the Apparatus 



After each use the sample bottles were 

 rinsed first with concentrated hydrochloric acid, 

 then twice with running sea water or tap water. 

 Care was taken that the latter rinses completely 

 filled the bottle thus elinninating acid fumes 

 from the bottle. This was followed by two 

 rinses, each with about 7 5 ml. of distilled 

 water. The bottles were then stored upside 

 down to drain. 



The filter holders were generally 

 washed once a day by immersing them in di- 

 lute hydrochloric acid solution (about 1 percent 

 HCl), followed by a rinse in fresh water. 



The glass pipettes were generally 

 washed once a day, first flushing thenn with 

 concentrated hydrochloric acid and then rinsing 

 several times with distilled water. 



Chlorophyll Determinations 



The methods used, both aboard ship 

 and in the laboratory, were adapted from 

 those described by Doty (1955). On the west- 

 bound leg of the cruise, usually at about 0800 

 each day, a sample was dipped from the surface 

 with a plastic bucket holding about 8 liters. A 

 half -teaspoon of magnesium carbonate was 

 stirred into the sample using aji ordinary phy- 

 sician's wooden spatula. Phytoplankton bearing 

 the chlorophyll pigments was collected by strain- 

 ing the sea-water sample through a 47 -mm. AA 

 Millipore filter disc (Creitz and Richards 1955). 

 The volume of water strained varied inversely 

 with the amount or rate of clogging of the Milli- 

 pore filters; ordinarily 4 or 5 liters were 

 filtered. 



/^ 



