The plant would additionally provide all the magnesium metal, 41 percent of the sulfur, 56 percent of the calcium, and 58 percent of the potassium used per year in the United States. The 1962 prices for these commodities ($705, $23.5, $4.2, and $31 per ton, respectively) used to compose the $180 million income these commodities should contribute to the $1,353 million annual income of the plant would be pretty shaky. The eighth largest income producer (strontium with 76,000 tons at $66 per ton and $5 million gross) would represent nearly eight times the annual use of this commodity in the United States, and there is not much call for it at all outside the United States.

Thus, in total $1,341 million of the plant's $1,352 million annual income would be pretty well shot before the first year of production was completed through simple overproduction, and a fair share of the remaining $12 million would be spent to haul away and dispose of the excess product. The $20,000 realized from 40 pounds of gold, the $28,600 realized from the 6.6 tons of uranium oxide, would not be of much help in paying the yearend bills.

McIlhenny and Ballard point out further that either where a recovery plant for other chemicals than those now recovered from sea water is put as a parasite on a present plant, or upon a fresh water conversion plant, the economic results are about the same under presently available technologies. The best of present saline water conversion plants concentrate the salt water no more than four times. Taking out the remaining water will not be much less costly than taking out all of the original water.

Other methods of concentrating specific compounds or elements from sea water than those contemplated above, are, of course, capable of being developed. As McIlhenny and Ballard say "Much greater problems in science have been solved when the solution looked fartherest away." But under present and immediately foreseeable knowledge, understanding, and technological art the situation for recovering much more variety of the dissolved minerals in the ocean looks bleak.

MINERALS FROM THE CONTINENTAL SHELF

Great quantities and considerable varieties of minerals are presently taken from the subsoil of the Continental Shelf. Petroleum, gas, limestone, and sulfur are some commodities presently produced in considerable volume from such situations in the United States. Magnetite (iron) ore is mined commercially in Japan in 90 feet of water; tin is so mined off Malaysia; diamonds off South Africa; thorium sands off south India; and other examples could be named (Mero, 1963).

There is no reason to think that the mineral composition of the Continental Shelf will prove to be any more or less rich than that of the adjacent land. Exploration involving seismic, gravity, and magnetic surveys are somewhat more simple and less expensive when done at sea than over land. Drilling costs at sea in depths up to 100 fathoms are practical in several instances now, and as experience accumulates they are likely to cheapen.

The big breakthrough in this field which appears to be on the immediate, or close horizon, is the ability of a man with a prospector's pick or other such instrument to live in specially prepared underwater dwelling for prolonged periods and work for hours at a time with scuba gear in depths up to 100 fathoms (Cousteau, 1964). The work of the last year or two in the Mediterranean and Red Sea under Costeau, and the work recently completed under U.S. Navy auspices off Florida, indicate satisfactorily that man is capable physically, physiologically, and psychologically of doing this. The present crude technology of these experiments seems likely to be advanced to more spohisticated stages rather rapidly.

Thus it looks as if instead of exploring the subsoil of the Continental Shelf indirectly by seismic, gravity, or magnetic surveys, or by a dredge pulled at the end of a long wire (as has yet been the practice up to now) man should soon be able to get down and work over the Continental Shelf by sight and touch, chipping off or digging up samples as required, without as much danger and hardships as those experienced by the desert prospector and his burro for the past 100 years on land.

This should inevitably, open up great new mineral wealth to all coastal countries having a substantial Continental Shelf. It was in anticipation of these developments that the nations of the world modified international law as they did in the "Convention on the Continental Shelf" so that the resources of these adjuncts of the continents could be brought to harvest under law.

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There is another sort of mineral on the Continental Shelf that is oceanic in origin and gives promise of much future production. These are the phosphorite nodule deposits that are found so plentifully on the Continental Shelf at all (or most) places where there is substantial upwelling of water from the deep sea. Known major deposits of phosphorite nodules have been found off Peru, Chile, Mexico, the west and east coasts of the United States, Argentina, Spain, South Africa, Japan, and on the submerged parts of several islands around the Indian Ocean.

A number of such deposits are known off the coast of California, some of which are expected to yield as much as 100 million tons of phosphorite (Mero, 1963). Since California uses an equivalent of over 400,000 tons of phosphate rock per year and has no commercial grades of phosphorite in deposits ashore, the discovery of these large offshore deposits has excited interest. A subsidiary of the Union Oil Co. did advance as far as to lease 30,000 acres of such deposits off San Diego from the Department of the Interior.

MINERALS FROM THE DEEP-SEA BED

The deep-sea bed has not, heretofore, been mined. There is reason to think that within the next generation deposits of truly oceanic origin on the deep-sea bed will become major sources of such metals as nickel, cobalt, copper, manganese, molybdenum, vanadium, and some others now used as essential ingredients in industry and not overly abundant on land in commercial deposits. Manganese nodules

The most exciting of these deposits are the so-called manganese nodules. They are called this because they always contain a substantial amount of manganese, and may be up to 50 percent manganese. However, they contain a number of other elements as well, in greater or lesser concentrations. The composition of the nodules vary considerably from ocean to oecan and as to locality within an ocean. In the Atlantic the composition of the nodules is relatively uniform and high in iron content. In the Pacific the composition of the nodules varies widely from place to place and apparently with some pattern (Mero, 1963).

One of the exciting aspects of these deposits is their enormous extent. They cover broad areas of all oceans. Their estimated present volume is substantially more than 1 trillion tons. Crude preliminary measurements in 25 locations in the Pacific indicated an average in the eastern part of that ocean of 30,000 tons of nodules per square mile. Similar measurements in the middle Pacific yielded an average of 55,000 tons per square mile, and in the western Pacific of 25,000 tons per square mile (Mero, 1963).

Assuming that only 10 percent of these nodule deposits prove economic to mine there are sufficient supplies of many metals in these nodules to last industry for thousands of years at present rates of production. There also is evidence that these nodules are accreting out of the ocean now as they have been doing for past millenia and that manganese is thus being accumulated three times as rapidly in them as it presently is being used by man, cobalt twice as fast, nickel as fast, etc. (Mero, 1963).

The nodules are loose on the ocean bottom. They are easily photographed and picked up in small lots by the oceanographer's dredge. They range in size from small peas to largish balls. There is no reason why they cannot be picked up readily by an oversized vacuum cleaner type of hydraulic dredge, pumped to the surface, and into waiting ore boats. Two companies are said presently to be in the design stage of equipment of this nature for this purpose.

The metallurgy presents problems that have not yet all been worked out but which are under active investigation by the Bureau of Mines and others.

The capital costs for engaging in such an enterprise would be substantial, but not overwhelmingly large for a number of U.S. companies. Mero (1963) estimated that a deep-sea hydraulic dredge of the type he had in mind would run about $6 million per unit, including design and development costs, and that a plant to process the nodules recovered would cost $60 to $70 million. He estimated that the gross value of the products recovered and processed per year by such equipment would be about $250 million and, at metal prices prevailing in April 1963, might yield a return on invested capital of between 30 and 100 perecnt per year. A single such operation, he reckoned, could produce about 50 percent of the U.S. consumption of nickel, over 100 percent of that manga

nese, about 5 percent of that of copper, about 35 percent of that of cobalt, about 7 percent of that of molybdenum, as well as appreciable amounts of vanadium, titantium, ziroconium, etc.

If this all appears to be somewhat visionary, it may be observed that one company thought well enough of the prospects to hire Mero away from the University of California to aid it in the design and development of equipment for these purposes.

Other mineral deposits of ocean origin

Although manganese nodule deposits hold presently the most immediate interest for large-scale mining of the deep-sea floor there are other major resources of similar origin on other parts of the ocean bottom that hold just as large interest for the longer term as techniques of ocean mining are developed and as high-grade ore deposits on land are exhausted. Substantially speaking, these deposits on the deep-sea floor are inexhaustible.

Red clay covers about 40 million square miles of ocean floor. At least 10 quadrillion tons of it are available. It is a mixture of compounds as are the manganese nodules. Elements of particular interest in it are copper, cobalt, aluminum, and nickel. These deposits have an average composition of 20-percent alumina and 0.02 percent copper. They contain at least 10 trillion tons of alumina and 10 billions tons of copper. Red clay is by present standards a lean ore, but the future may consider it to be richer (Mero, 1963).

Calcareous oozes cover almost 50 percent of the ocean floor, or some 50 million square miles. Some assay as high as 95-percent calcium carbonate, and are very similar in composition to the compounds which account for 95 percent of the cement-rock market. Deposits of nodules assaying about 75 percent barium sulphate are found in several locations off California and Ceylon. About 11 million square miles of the ocean floor is covered by diatomaceous oozes which in some cases are almost pure silica. They could be used for any purpose for which diatomaceous earth is now used.

Although up to now these enormous deposits of minerals of oceanic origin have been sheltered from man by the thick overburden of water and the lack of practical technologies with which to deal with them, this will not necessarily remain the case for long. Actually there are some attractions to deep-sea mining as compared to land mining.

Because of their common property nature the political and property costs and risks associated with land deposits are absent. Aside from water there is no overburden to remove, no drilling costs, no need for explosives and ore breakage. There are no drifts to make or shafts to sink and no townsites to buy and develop. With available camera equipment the whole deposit can be explored and every ton of ore to be expected accounted for before mining starts. Ocean mining lends itself to full automation with minimum labor requirements. Cheap sea transportation can be used from mine to market without the need for other intervening forms of transportation (Mero, 1963).

FOOD FROM THE SEA

As is well-known, all life on earth is nourished by the basic products of interaction between solar radiation, carbon dioxide, chlorophyll, trace elements, and water. The basic output of this transmutation is carbohydrates, proteins, vitamins, oils, and the other things composing living matter. Only the plants (in significant amount) contain the chlorophyill through the agency of which the solar energy can be bound with chemicals to create living matter. Upon these plants the great range of planetary animal life, including ourselves, fully depends.

Sea water has dissolved in it all of the chemical ingredients required to support plant production. It receives over 70 percent of the solar radiation that strikes the earth. Scarcely a drop of salt water within 100 feet of the sea surface is devoid of plant life, and plant life is found deeper in the ocean than that in considerable amounts. Accordingly, as with so many other things about the ocean, it supports more photosynthesis and plant-food production that can be readily imagined or than a much vaster human population than that presently living could eat.

The ocean varies as much by area in its production of life as does the land. There are ocean "deserts" as well as extremely fertile ocean areas, as with the land. Mostly this is due to certain required chemicals being exhausted in the

superficial layers of the ocean where insolation is heaviest and plantlife most abundant.

By contrast, below the level to which solar radiation can reach and plant life subsists (say 150-200 feet in most ocean areas) these chemicals are superabundant. Where there is vertical circulation of these nutrient rich deeper waters to the surface, plantlife again flourishes in abundance comparable with the most productive farmlands. Such places are Peru, Chile, California, South West Africa, West India, South East Arabia, the Japanese home islands, the Grand Banks, etc., etc.

With the ocean operating just as it is now a conservative estimate of the weight of carbon fixed into living matter annually by ocean plants (phytoplankton) is 19 billion tons (Schaefer, 1964). Although we are all acquainted with the kelps and algae of the seashore and shallow inshore waters, most of ocean plantlife (as contrasted with most of that with which we are acquainted on land) is composed of one-celled organisms of microscopic size.

Although they are produced in these vast amounts in the ocean, and sometimes in such profusion that miles of ocean are rendered cloudy, or soupy, or even colored by their presence, it is unlikely that they will ever be of much importance to man directly as food. The reasons for this are several. The most important is that even a maximum abundance there is still so little dry weight of plantlife per cubic meter of water that the cost of separating the water from the plantlife is beyond all possible range of direct value of the living matter as food. This highly abundant phytoplankton must be much concentrated by other organisms before it can be further concentrated by man and used by him directly.

This concentration is done by animals of all sizes which graze upon the plants of the ocean much as cattle graze upon the grass of the prairie. Thus animal protein arises in vast bulk in the ocean, in greater bulk than man needs or could use. Upon the smaller of these multitudinous one-celled animals and plants feed multicelled animals of larger size that may be visible to the human eye, or even rather large (as with jellyfish, krill, etc.), which drift freely with the ocean currents and are called plankton. Where plant plankton is being produced actively, and animal plankton is grazing on it profusely, it is possible with a small meshed net to catch pounds or gallons of such plankton quite easily.

From this fact publicists have put forward the idea that plankton soup will be the salvation of mankind. This is sheer buncombe. In the first place plankton soup is not something for which children would cry for a second bowl because of its fine taste. In the second place its separation from the water and processing into stable and transportable shape is impractically costly. Thirdly, it not only contains a great variety of plants and animals that could not be separated from each other practically, but in any one place in the ocean the compositions of the plankton catch changes grossly from day to day in a manner making a reasonably standard product quite impossible. Lastly, the total productivity of ocean areas change rapidly from day to day and from season to season in manners as yet unpredictable, and the frequent location of maximum plankton concentrations of the nature to which we are referring would not be easy or cheap.

Although very large quantities of organic material is converted into protein directly utilizable by man by oysters, clams, mussels, barnacles, shrimp, etc., and phytoplankton is put into directly utilizable form on a large scale by such fish as anchovies, another level of concentration by living things is ordinarily required before all of this vast production of tiny oceanic food units can be captured by man in a form that he can use and at cost that he can afford. This is done by the bony fish, the shark, the squid, whales, porpoise, and the myriad other larger animals of the ocean. When these proliferate and congregate in such manner that man can cheaply catch them, process them into acceptable food, and transport them to consumption centers in still acceptable form at acceptable price, only then does ocean production become food for man.

THE WEB OF LIFE

The web of life in the ocean is incredibly complex as we know it now, and we are still pretty ignorant about it. Well over half (perhaps as much as 90 percent) of the organic matter in the ocean is not in living form at all, but is in forms resulting from excretion, death, bacterial action, and enzymatic dissociation that has left it outside the living form (Kesteven, 1962).

In any event, in a rich sea area like that off Peru, the first life of practical size for man to use in large volume is a fish like the anchovy that lives normally almost

entirely on microscopic phytoplankton. Associated with the anchovy are sardines, some mackerels, and some other fishes that appear to be able to subsist indiscriminately on plant or animal plankton. These are the sorts of fish that are most abundant and exist in great schools that can be caught easily and cheaply. Although properly prepared these fish are excellent as direct human food, most people do not accept them readily and the market for them is thin. They go into fishmeal which is fed to poultry, swine, and cattle, by which route they enter the human diet, and into fish oil which is mostly used for margarine.

Upon these vast swarms of herbivores and half carnivores live the bonito, the tuna, and such fishes that are readily acceptable directly by humans in their diet. Upon the others, and these latter, subsist the squid and great sharks; upon the great squid live the giant sperm whales.

A wholly different chain of life of similar complexity arises from the shallow ocean floor involving the bottom-living diatoms and detritus, sedentary molluscs (such as clams, oysters, and mussels), the crustacea (such as shrimp, crab, and lobster), and bottom fishes (such as flounders, cods, etc.,) etc.

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At intermediate depths are other chains of life of similar complexity. contain fish like the hake which are near the bottom at one time and even up to the surface at others, the ocean perch which regularly inhibit the middle layers well up from the bottom, the lantern fishes which may move up and down from the dark deep to the surface diurnally, etc.

All of these chains of life interlock in various feeding and life history manners, in incredible complexity.

The reason for noting this complex natural scene even so hastily is to point out that the carbon originally fixed by the plants into organic matter transfers from stage to stage of life in the ocean as one of these organisms is eaten by another up the scale, and then by another and yet another. These stages are called trophic levels.

As the carbon moves from trophic level to trophic level, it is diminished in volume at the new trophic level. The reason for this is that much of it is lost through metabolic action and waste products that are excreted (carbon dioxide in breathing, urea products, and feces, as well as cast off shells in crustacea, etc.). For a long time it has been customary among scientists dealing with this subject to use the rule of thumb that as the biological carbon moves from one trophic level to another it diminishes by a factor of 10 For instance, 10 pounds of anchovy eaten by 1 bonito will yield 1 pound of live bonito.

It is now becoming well known that this conversion factor is entirely too conservative. Lindner (personal communication) finds that shrimp convert their food into body weight with an efficiency of about 25 percent. Lasker (personal communication) working with the krill (Euphausia pacifica) finds that when it is feeding either wholly on zooplankton, it converts its food to body weight at efficiencies ranging from 11 percent to 40 percent, and averaging (as with shrimp) about 25 percent.

Schaefer (1964) has calculated what would happen with 19 billion tons of carbon fixed into phytoplankton if it were converted into second stage carnivores (just about the average tropic level at which he estimated the world fisheries to be presently working) at ecological efficiencies of 10 percent, 15 percent, and 20 percent. He arrives at a total weight of second stage carnivores (fish, shellfish, squid, etc.) of 190 million tons at the 10-percent level, 640 million tons at the 15-percent level, and 1.52 billion tons at the 20-percent ecological efficiency annual production would be 7.6 billion tons.

Adequate studies have not yet been made which would convert ecological efficiency as Schaefer uses the term, or the more generally used concept of food conversion to body weight, into a general idea of overall ocean efficiency in conversion of food from one trophic level to another. Since a 25-percent average conversion of food to body weight does not appear to be out of expectation for marine animals (chickens produce 1 pound of weight from less than 3 pounds of feed) and the 19 billion tons of biologically fixed carbon per year in phytoplankton is a notably conservative estimate, perhaps a rough number of 2 billion tons per year of second stage carnivore generation could be taken as reasonably conservative estimate of the actual production of fish and squid by the ocean per year in forms large enough to be harvested and used by man.