METHODS 



Salinity 



Dissolved oxygen -' 



1/ 



Reagents: 



1. Manganous Chloride (MnC1.4H 2 U) - 

 dissolve 800 gm. manganous chloride 

 in 1570 ml. distilled water . 



2. Potassium Hydroxide -Potassium Iodide 

 - dissolve 500 gm. potassium hydrox- 

 ide and 100 gm . potassium iodide in 

 distilled water, dilute to two liters, 

 and store in dark bottle. 



3. Concentrated Hydrochloric Acid. 



4. Sodium Thiosulfate (Na SO .5H u) - 

 dissolve 3.5 gm . sodium Thiosulfate in 

 one liter freshly boiled distilled water, 

 add 0.1 gm . sodium carbonate, and 

 store in dark bottle . 



5. Standard Solution (0.01 N Potassium 

 Biniodate) - dissolve 0.3250 gm . 

 potassium biniodate /KH(IO > /in dis- 

 tilled water, and dilute to one liter . 



Procedure : (determination made aboard ship) 



Add 2 ml. manganous chloride and 2 ml. 

 potassium hydroxide -potassium iodide to the 

 sample (inserting the tip of the buret to below 

 the surface), replace stopper carefully without 

 trapping any air, and mix thoroughly. Allow to 

 stand until ppt. settles. Add 2 ml. cone, hy- 

 drochloric acid and shake until ppt. dissolves. 

 Pipet 100 ml. of sample into a 250 ml. flask, 

 titrate with sodium thiosulfate until color be- 

 comes faint yellow, add starch indicator, and 

 continue titrating until the blue color disap- 

 pears . 



1/ Wooster, Warren S., 1950 

 2/ Harvey, H. W., 1948 



Two or more chlorinity determinations 

 were run on each sample, employing the 

 Knudsen method; and these were converted to 

 salinity. 



Total phosphorous _' 



Reagents : 



1 . 50% Sulfuric Acid - mix equal volumes 

 of distilled water and cone . sulfuric 

 acid. 



2. Molybdic Acid - dissolve 3.3 gm. 

 ammonium molybdate /(NH . ), Mo 7 0„. 

 , 4HoO / in a solution of 3 ml . cone . 

 sulfuric acid and 200 ml. distilled 

 water. 



3. Stannous Chloride (SnCl 2 .2H 0) - dis- 

 solve 1.2 gm. stannous chloride in 5 

 ml . cone . hydrochloric acid, and dilute 

 to 50 ml. with distilled water (solution 

 made up daily) . 



4. Standard Stock Solution (2000 ,ug at P/L) 

 - dissolve .6120 gm . of di-sodium, 

 beta-glycerophosphoric acid in distilled 

 water, and dilute to one liter. 



Procedure : 



Add 1.5 ml. of 50% sulfuric acid to 100 ml. 

 of sample. Shake samples and allow to stand 

 until the thorium carbonate is dissolved, usu- 

 ally three or four days. Pipet 25 ml. samples 

 into 60 ml. flasks, cover with 30 ml. beakers, 

 and autoclave for 6 hours at 30-40 lbs. pres- 

 sure. Remove from autoclave, cool, add 0.75 

 ml. molybdic acid, swirl, and add 1 drop of 

 stannous chloride _' . Let stand for 20-30 

 minutes for maximum color development, 

 transfer to 23 ml. absorption cells, and read 

 densities using a red filter (650 m,u). 



3/ Allow a lapse of 30-60 seconds between 

 additions of stannous chloride to samples 

 to ensure equal development time. 



