glass wool above the stopcock of 

 a 50-ml. buret and adding amber- 

 lite IRA 400 (OH) anion exchange 

 resin to a depth of 30 cm. in the 

 buret. (The colunnn is recharged 

 after each third sample is passed 

 through by washing with 150 ml. of 

 3N hydrochloric acid and rinsing 

 with 150 ml. of freshly boiled and 

 cooled distilled water). 



Procedure : Chow and Thompson 

 (1955) reported a procedure for deter- 

 mining strontium in seawater. This was 

 used as a guide in developing a method 

 for determining strontium in marine 

 sediments. 



Weigh 1.0 gm . of dried sample into 

 a 1 50-ml. beaker and add 10 ml. of 6N 

 hydrochloric acid and 5 ml. of con- 

 centrated nitric acid. Heat at medium 

 setting on an electric hot plate until 

 evaporation is complete, bake for 10 

 minutes, allow to cool, and add 1 ml. 

 of 6N hydrochloric acid and 15 ml. of 

 distilled water. Heat to near boiling 

 and filter the mixture using a medium - 

 flow filter paper, let the filtrate flow 

 directly into the anion exchange col- 

 >imn, and catch effluent in a 100-ml. 

 volumetric flask. Wash the filter and 

 column with CO^-free distilled water, 

 catching the washings in the 100-ml. 

 flask also, add 5 ml. of the 200 p. p.m. 

 strontium standard solution (repre- 

 senting 10 p. p.m. added strontium) 

 and finish filling to nriark with distilled 

 water. Set aside for flame analysis. 



Make up standards of 0, 10, 20, 30, 

 40 and 50 p. p.m. strontium from the 

 200 p. p.m. strontium standard solution. 

 Adjust the Beckman Model DU spectro- 

 photometer to read 100 percent emis- 

 sion for the 50 p. p.m. strontium stand- 

 ard at 460.7 m mu wave length. Read 

 and record the flame intensity of each 

 of the standards, taking and recording 

 a reading on distilled water subsequent 

 to each standard. Set the wave length 

 at 454 m mu and determine and record 

 flame intensities of standards and sub- 

 sequent distilled water. Subtract flame 

 intensities of distilled water from those 

 of standards at both wave lengths, then 

 deduct the remainder of the flame in- 

 tensity taken at 454 m mu from that 



taken at 460.7 and plot these remainders 

 against the concentrations. From this 

 standard curve determine the net flame 

 intensity representing 100 p. p.m. 

 strontium . 



Determine the flame intensities of 

 each unknown with a subsequent dis- 

 tilled water reading for each at 460.7 

 m mu and at 454 m mu wave length. 

 Subtract readings of water from those 

 of the unknowns, and then subtract 

 the remainder of the intensity of 454 

 m mu from that taken at 460.7 m mu 

 and from this remainder subtract the 

 net flame intensity representing 10 

 p. p.m. strontium to compensate for 

 the 10 p. p.m. strontium added to each 

 unknown. Use the net intensity from 

 the unknowns and the standard curve 

 to find the strontium concentration. 

 Report as percent strontium on a dry 

 weight basis. Spectrophotometer set- 

 tings as follows: Photomultiplier - set 

 to null dark current; sensitivity con- 

 trol - counterclockwise extreme; wave 

 length - strontium spectral line 460.7 

 m mu and also flame background at 

 454 m mu; selector switch - 0.1; 

 phototube resistor - 2000 megohms; 

 slit width - .01 to .02 mm.; acetylene 

 pressure - 3.5 p.s.i.; oxygen pres- 

 sure - 12 p.s.i. 



Chloride 

 Reagents : 



1. Standard chloride solution [O. ION 

 sodium chloride (NaCl)] -dissolve 

 5.8460 gms. of sodium chloride in 

 distilled water and dilute to 1 liter. 



2. Silver nitrate (AgNOs) - dissolve 

 7.5 gms. of silver nitrate in dis- 

 tilled water and dilute to 1 liter. 



3. Indicator [8 percent potassium 

 chron^ate (K2Cr04) solution] -dis- 

 solve 8.0 gms. of potassium chro- 

 mate in distilled water and dilute to 

 100 ml. 



Procedure : A modification of the 

 procedure used by Anderson, Gehringer 

 and Cohen (1956a) for salinity (Knudsen 

 method) was employed on leachings of 

 sediments to determine their chloride 

 content. 



12 



