Chapter II 



17 



The Marine Environment 



Chemical composition of sea water: — Sea water is a physiologically 

 balanced salt solution containing more than half of the known elements. 

 It is a dilute solution of several salts with some dissolved gases and traces 

 of a vast number of organic compounds. 



Except for a few constituents which are produced or consumed by 

 biological agencies, the composition of sea water is relatively constant. 

 The concentration of the principal inorganic solutes in sea water having 

 a salinity of 34.325°/oo is given in Table IV. 



Table IV. — Concentration of elements, exclusive of gases, in sea water having a salinity of 

 34.32 f I vi {from data recorded by Sverdrup et at., ig42) : — 



* The quantity of the elements marked with an asterisk is highly variable in sea water primarily due to bio- 

 logical activity. The concentration given is the maximum ordinarily found. 



The chlorine and bromine occur almost exclusively as chloride and 

 bromide anions. Similarly sodium, magnesium, calcium, potassium, and 

 strontium occur as cations. The oxygen reported in Table IV occurs 

 mostly in sulfate ions, with smaller quantities in bicarbonate, borate, 

 phosphate, nitrite, and nitrate ions. The nitrogen occurs as ammonium, 

 nitrite, or nitrate ions and to a lesser extent in organic compounds. The 

 ratios of the three principal anions of sea water, i.e., carbonates, sulfates, 

 and chlorides in sea water are the reverse of the ratios of these anions in 

 river water: 



Similarly the ratios of cations, particularly sodium and calcium, are 

 different in sea water and in river water: 



The ratios are calculated from data given by Clarke (1924) on the an- 

 alyses of river water and sea water. 



