40 



An iTxtegral part of this basic problem is the rrore specific 

 one of the chei.dca?. events by which the pre:oonderance of calci-a.r., 

 and of carbonates, rhich characteri?^es river water as a v:hole, is 

 so uriforml3^ altered into the preponderance of sodivim and of 

 ch?.oridCE that characterizes the sea wator, every?/here and at all 

 times, even "onder the r.ioct diverse conditions. The fact (recently 

 demonstrated) that this characteristic state obtains close in to the 

 mouths of great rivers, although the diluting effect of the latter 

 may be apparent for long distances, i.e., that the transition is 

 more sudden with respect to the chenical co.roosition of the water 

 than with respect to its saline concentration, shows that we have 

 here to do with something ir.ore fundaiv.ental than with a -.nere with- 

 drawal of li.ne of shell-bearinp; orga"is.ns, such as would allow 

 sodium to acc-irrmlate out of proportion. 



Contrasted with the processes that succeed in r.iaintainin;5 sea 

 water so nearly unifor.ii all over the ocean are the chemical re- 

 actions that affect the regional and periodic variations that do 

 exist in it, and which involve a wide range of substances, and com- 

 binations of substances. Basic problems, in this connection, 

 because of their role in the general cycle of matter in the sea, 

 (Page 65 ) center around the cherdstry of lime and of carbonic acid, 

 bound up with the degree of alkalinity of the water. The chenist 

 has to do here with a very complex series of reactions in which gas 

 tension between water and atn^osphere at different tomperature.i, 

 withdrawals of lime and carbon by organic agency, precipitation of 

 lime, re-solution (which goes forward at different rates for 

 different varieties of carbonate of lime and different line salts; 

 and at different rates according to amount of free carbon dio'iide 

 in the v;ater) and alterations in the degree of ionic dissociation 

 of different salts in the solution, all play a part. 



The importance of this general field in its relation to s^J.b- 

 m.arine seii;':^.entation, and to the accumulation of lime deposits 

 generally, as v;ell as in its more strictly biological aspect, is 

 touched on in another cicjtion (Fage > ). Cne significant chemical 

 problem hinges on the fact that in spite of all the various re- 

 actions that tend to alter the proportion of total bases to total 

 acid radicals, and that are therefore tending to alter the degree 

 of alkalinity of the water (and do actually so alter it v/ithin 

 narrov; limits) by adding or withdrawing carbon dioxide and calcium, 

 or by altering the relative proportions of the normal carbonates to 

 acid bicarbonatcs in the solution, the balance is so closely main- 

 tained at all places and at all times in the open sea that the 

 alkalinity never rises above or falls below the narrow limits -jithin 

 which the organic life (as regulated to marine conditions) is able 

 to exist. This phenomenon is as important in ocean economy, 

 and as deserving of the closest chemical analysis, as i s the 

 stability of the alkalinity of blood serum in h^jman physiology. 



In this instance, as in so m.any oceanographic problems, two 

 phases are involved. First, the chemical potenoialities in the case 

 must be determined, and these have naturally been the subject of 

 much discussion, leading to substantial agreement with regard to 

 some. The significant task is then to determine in what proportion 

 the theoretic reactions do actually take place in the sea, in -That 



