14 - 



potential to surface current was by the formula 

 E = - VHzS where E is the measured potential, V 

 the surface current, Hz the vertical component of the 

 earth's magnetic field, and S the interelectrode dis- 

 tance. No corrections, therefore, have been made 

 for "depth of current, " "electrode droop, " or 

 "windage on electrodes. " 



Primary Production 



Due to a number of technical difficulties, the 

 productivity data could not be completed in time to 

 be included in this report. These data will appear in 

 the next report in the form of an appendix. The pro- 

 ductivity techniques employed on SCOT are given below 

 for reference. 



The carbon-14 method was employed in these studies 

 to determine the rate of carbon fixation by the phyto- 

 plankton. The carbon-14 solution was prepared and 

 standardized in the manner described by Steemann 

 Nielsen (Jour, du Cons., 18 (2): 117-140, 1952) with 

 the exception that glass redistilled water rather than 

 artificial sea water was used as the solvent. The C ■* 

 solution was then filtered through an HA Millipore 

 filter and put in 10-ml glass ampules which were 

 immediately autoclaved. The C solution was added 

 with a plastic syringe and stainless steel needle pro- 

 vided with a positive stop. The radioactivity of the 

 samples was measured with an NMC-PC#1 propor- 

 tional counter. 



All of 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 (H CI) 

 and sea-water rinse. Immediately prior to drawing 

 of the sample, each bottle was rinsed three or more 

 times with sea water collected at the sample depth. 



The in situ vertical measurements of productivity 

 were carried out in the following manner. A water 

 sample was collected at each desired depth with the 

 plastic Van Dorn-type sampler shortly before day- 

 light. The samples were transferred to clean, well- 

 aged, 125-ml Pyrex bottles and the C solution in- 

 jected with a plastic hypodermic syringe and stainless 

 steel needle. The samples were resuspended at or 

 slightly before dawn, at approximately the depth at 

 which they were collected, on a weighted rope sup- 

 ported by a free-floating glass buoy (14 in. in diameter) 

 enclosed in a cord netting and attached to a bamboo 

 pole bearing a flag and radar reflector at its top. The 

 surface sample was attached to the side of the glass 

 buoy, just under the sea surface. The samples were 

 collected at noon, local time, and were promptly 

 filtered and dried for counting. 



The samples incubated on shipboard were inoculated 

 with C in the same manner as the in situ and trail- 

 ing bottle material. The incubator itself was similar 

 to that employed by Steemann Nielsen (op . cit. ). 

 Temperature control was achieved by circulating 

 subsurface sea water through the water bath at a rate 

 of 4-6 1. per minute. The temperature in the bath 

 fluctuated somewhat but never exceeded the sea- 

 surface temperature by more than 2. 3°C, and usu- 

 ally by less than 1°C. Temperatures less than that 

 of the sea surface were not observed in the incubator. 

 The samples were illuminated by a bank of 10 daylight- 

 type fluorescent lamps. The lamp bank was moveable 

 and was the means employed in keeping the intensity 

 of light at the bottles at 1000 foot-candles. 



In situ surface productivity was measured using 

 samples dipped from the sea surface with a plastic 

 bucket at either sunrise or local noon. The samples 

 were placed in clean, well-aged, 250-ml or 125-ml 

 Pyrex bottles inoculated with C^"*, and trailed astern 

 of the vessel, just under or on the top of the sea sur- 

 face, until local noon or sunset, respectively. The 

 samples were filtered immediately and placed in a 

 vacuum desiccator for drying. 



