THE FUTURE OF OCEANOGRAPHY — SPILHAUS 365 



be used. Freezing of sea water in nature leaves about one-third of 

 the salts in pockets in the ice, but the technique of zone refining of 

 metals which results in ultra purity suggests the method of "zone" 

 freezing, which would have the advantage over distillation in that 

 it requires only about one-sixth of the power. Semipermeable mem- 

 branes, ion exchange, and even salt-eating bacteria are other 

 possibilities. 



As the need for fresh water increases, more and more rivers will be 

 stopped from rmming into the sea. This does not mean that the 

 rivers will cease to exist, but simply that their waters will be used and 

 reused and returned to the sea through the evaporative cycle rather 

 than by waste flow. Every drop of fresh water that flows into the sea 

 represents a waste of the solar energy that was used to distill it. The 

 rivers of the world carry 2,000 million tons of salt each year into 

 the oceans, and one might think that by tampering with river flow 

 we would upset the balance of ocean salts. But to give an idea of 

 how tiny this efi'ect is, the annual amount of salt going into the sea 

 is only one hundred-millionth of the total already there. 



As well as producing fresh water for use on land, we will develop 

 ways of producing it under the sea. This is done now by evaporation 

 in the nuclear submarines, as it is indeed on surface vessels. When 

 we understand how penguins can exist without a drop of fresh water 

 and exclude the excess salt, perhaps we can build counterparts of their 

 mechanism to get fresh water. 



Before man required fresh water from the sea, he needed just the 

 opposite — to extract the salt. This is an ancient art ; at first the salt 

 was used only for the seasoning of food. But in the last 40 years, not 

 only have sodium, potassium, and magnesium salts been extracted 

 economically, but also bromine and magnesium metal. The difficulty 

 of getting anything out of sea water is that everything occurs in a 

 highly dilute state, and large amounts of water have to be pumped 

 and processed. But power is getting cheaper, and perhaps, instead 

 of pumping sea water through plants on land, we will have floating 

 processing plants at sea, propelling themselves through the water as 

 they take what they need from it, just as marine animals do. The 

 advantage of such floating "refineries" is that they do not occupy 

 expensive shore land and can move to areas of rich sea "ore." Perhaps 

 deuterium taken from the sea water itself will power them. 



Many valuable elements are so dilute that it is not economical to 

 extract them from sea water, yet nature concentrates them in high- 

 grade deposits on the floor of the sea. Nodules on the sea bottom are 

 already being mined for phosphorus, and nodules of manganese, not 

 valuable enough in itself, may contain enough valuable nickel, cobalt, 

 molybdenum, and zirconium to warrant scraping them off the bottom 

 in a deep sea mining enterprise. The most interesting facet of this 



