Meaning of OCEAN in English

OCEAN

continuous body of salt water that is contained in enormous basins on the Earth's surface. It covers about 362,000,000 square km (140,000,000 square miles)nearly 71 percent of the terrestrial surface. This world ocean is commonly divided into a number of major oceans and smaller seas. The three principal oceans, the Pacific, Atlantic, and Indian, are largely delimited by land and submarine topographic boundaries. All are in open connection with what is sometimes called the Southern Ocean, the stretch of water encircling the Antarctic continent. By convention, the Southern Ocean has been divided into three portions, one for each of the three main oceans. Including the appropriate sectors of the Southern Ocean, the Pacific accounts for 46 percent of the total area of marine waters, and the Atlantic and the Indian for 24 and 20 percent, respectively. Important marginal seas exist, primarily in the Northern Hemisphere. They are partially enclosed by landmasses or island arcs. The largest are the Arctic and adjacent seas, Asiatic Mediterranean (between Australia and Southeast Asia), Caribbean and adjacent waters, Mediterranean (European), Bering Sea, Sea of Okhotsk, Yellow and East China seas, and Sea of Japan. The average depth of the ocean is 3.7 km (2.3 miles). From the continental shelf break, which commonly lies at depths between 100 and 200 m (330 to 660 feet), the continental slope descends to extensive abyssal plains. Approximately 75 percent of the ocean floor falls within the depth range of 3 to 6 km, and only about 1 percent lies deeper. The deepest waters occur in relatively narrow trenches, mostly associated with Pacific island arcs, the maximum depth recorded being 11,034 m in the Mariana Trench. Substantial areas of the seabed are covered by unconsolidated sediment that overlies consolidated sediment and crustal igneous rocks. While large areas of the ocean floor are notably flat, various mountainous features occur, such as seamounts. A major feature is the so-called midocean ridge, which extends with many branches through the major oceans. Ridge crests rise 2 to 3 km above the deep ocean floor. Volcanically active ridge areas are sites for the formation of new oceanic basaltic crust and play a central role in seafloor spreading (see plate tectonics). Recent discoveries on the Pacific Ocean ridge have shown that in regions of active formation of new crust, seawater is circulated through the basaltic rock and greatly altered by reactions at high temperatures. Solutions that have undergone these hydrothermal interactions are returned to the ocean through vents in the crust. Temperatures up to 350 C (660 F) have been recorded at certain vents. The general circulation of water throughout the ocean occurs rapidly in terms of geologic time scales, with mean lifetimes for water molecules in the deep ocean of a few hundred to approximately 1,000 years. At the surface, currents are created by the frictional effects of wind stress on the upper ocean layer. The major wind systems determine the initial directions of the major currents, which can be modified by effects of the Earth's rotation and by topographic boundaries. An example is the clockwise gyre in the tropical and temperate parts of the North Atlantic Ocean, which includes the intensified western boundary currents that feed into the Gulf Stream. Somewhat similar gyre circulations are set up in other regions. Adjacent to the eastern continental margins of the major oceans, surface waters commonly move away from the coast and are replaced by colder and nutrient-richer water from intermediate depths. Such areas of coastal upwelling are often biologically productive and support fisheries. The wind-driven circulation affects the ocean to variable depths. The characteristics of most intermediate and all deep waters are, however, established by the thermosaline circulation. This is created by the sinking of waters that become denser from cooling in high-latitude regions and then sink until they reach a depth at which there is water of the same density, where they flow laterally. A limited number of water types with characteristic temperatures and salinities are formed, and their mixing produces distinguishable water masses occupying particular depth ranges in different parts of the ocean. Most flows uninfluenced by surface circulation are broadly from south to north or vice versa, but there are significant exceptions, such as water of Mediterranean origin that occurs at intermediate depths in parts of the Atlantic Ocean. Many important characteristics of the ocean are determined by the temperature and salinity of seawater, which, together with pressure, determine its density. The major heating of the ocean occurs by absorption of solar energy at the surface, and the surface temperature shows a pronounced variation with latitude. The distribution of surface temperature is, however, influenced appreciably by heat transport in surface currents and by other regional features such as upwelling. The temperature range for the open ocean is from less than -1 to 28 C (30 to 82 F). In tropical and temperate latitudes the temperature of ocean waters decreases markedly in the thermocline zone below the well-mixed upper layer, which typically extends to about 100 m. Changes below 1 km are gradual, leading to bottom temperatures normally below 2 C. About 50 percent of the total volume of the ocean has temperatures between 1.3 and 3.8 C. Salinity, a measure of the proportion of dissolved salt in seawater, varies in surface waters mainly according to the local balance between evaporative loss of water and input in the form of rainfall. The average oceanic salinity is 34.7 parts per thousand. Areas with a significant influx of fresh water from many large rivers or of meltwater from icebergs have a slightly lower salinity, while those with unusually high evaporation have a slightly higher salt content. Seawater contains a wide variety of dissolved inorganic substances, gases, and organic substances. In addition to these dissolved components, it contains suspended particulate matter (e.g., plankton). The most abundant inorganic constituents, excluding water, are, in order, chloride, sodium, sulfate, magnesium, calcium, potassium, and bicarbonate. These major constituents, unlike many of the materials that occur in trace amounts, vary in concentration in nearly constant proportions to the salinity. Ocean water is slightly alkaline, with a pH close to 8. Geochemists consider that the major compositional features of seawater have been more or less constant for at least the past 600,000,000 years, despite the continuous input and removal of material. The oceans appear to have been formed early in the Earth's history. As the planet heated up and became differentiated into three major zones (core, mantle, and crust), large amounts of water vapour, along with other excess volatile materials, were released from the interior by volcanism and carried to the surface in lava. The water vapour escaped from the lava as hot clouds, which subsequently condensed to yield enough water to form the oceans. continuous body of salt water that is contained in enormous basins on the Earth's surface. When viewed from space, the predominance of the oceans on the Earth is readily apparent. The oceans and their marginal seas cover nearly 71 percent of the Earth's surface, with an average depth of 3,795 metres (12,450 feet). The exposed land occupies the remaining 29 percent of the planetary surface and has a mean elevation of only 840 metres (2,756 feet). Actually, all the elevated land could be hidden under the oceans and the Earth reduced to a smooth sphere that would be completely covered by a continuous layer of seawater 2,686 metres deep. This is known as the sphere depth of the oceans and serves to underscore the abundance of water on the Earth's surface. The Earth is unique in the solar system because of its distance from the Sun and its period of rotation. These combine to subject the Earth to a solar radiation level that maintains the planet at a mean surface temperature of 16 C (61 F), which varies little over annual and night-day cycles. This mean temperature allows water to exist on the Earth in all three of its phasessolid, liquid, and gaseous. No other planet in the solar system has this feature. The liquid phase predominates on the Earth. By volume, 97.957 percent of the water on the planet exists as oceanic water and associated sea ice. The gaseous phase and droplet water in the atmosphere constitute 0.001 percent. Fresh water in lakes and streams makes up 0.036 percent, while groundwater is 10 times more abundant at 0.365 percent. Glaciers and ice caps constitute 1.641 percent of the Earth's total water volume. Each of the above is considered to be a reservoir of water. Water continuously circulates between these reservoirs in what is called the hydrologic cycle, which is driven by energy from the Sun. Evaporation, precipitation, movement of the atmosphere, and the downhill flow of river water, glaciers, and groundwater keep water in motion between the reservoirs and maintain the hydrologic cycle. The large range of volumes in these reservoirs and the rates at which water cycles between them combine to create important conditions on the Earth. If small changes occur in the rate at which water is cycled into or out of a reservoir, the volume of a reservoir changes. These volume changes may be relatively large and rapid in a small reservoir or small and slow in a large reservoir. A small percentage change in the volume of the oceans may produce a large proportional change in the land-ice reservoir, thereby promoting glacial and interglacial stages. The rate at which water enters or leaves a reservoir divided into the reservoir volume determines the residence time of water in the reservoir. The residence time of water in a reservoir, in turn, governs many of the properties of that reservoir. This article focuses on the oceanic reservoir of the world. It discusses in general terms the properties of this body of water and the processes that occur within it and at its boundaries with the atmosphere and the crust of the Earth. The article also delineates the major features of the ocean basins, along with those of the continental margins and shorelines. Considered, too, are the economic aspects of the oceans, including some of the environmental problems linked with the utilization of marine resources. For specifics concerning the relationship of the oceans to the other reservoirs of the Earth's waters, see hydrosphere. See also biosphere for coverage of the life-forms that populate the marine environment. Information about the nature, scope, and methods of oceanography and marine geology are provided in hydrologic sciences. Additional reading General considerations Broad overviews of the oceans are provided by Keith Stowe, Ocean Science, 2nd ed. (1983); David Tolmazin, Elements of Dynamic Oceanography (1985); David A. Ross, Introduction to Oceanography, 4th ed. (1988); Alyn C. Duxbury and Alison B. Duxbury, An Introduction to the World's Oceans, 3rd ed. (1991); M. Grant Gross, Oceanography, a View of the Earth, 5th ed. (1990); and Tom Beer, Environmental Oceanography: An Introduction to the Behaviour of Coastal Waters (1983). Alastair Couper (ed.), The Times Atlas and Encyclopedia of the Sea (1989), provides a graphic look at all aspects of the ocean. Ocean Yearbook (annual), contains essays on resources, transportation, and marine science, among other topics. Gustaf Arrhenius, Bibhas R. De, and Hannes Alfvn, Origin of the Ocean, in The Sea, vol. 5, Marine Chemistry, ed. by Edward D. Goldberg (1974), pp. 839861, provides a thorough discussion of the formation of water on the Earth during early geologic history. A. Guilcher, Continental Shelf and Slope (Continental Margins), in The Sea, vol. 3, The Earth Beneath the Sea: History, ed. by M.N. Hill (1963), describes the distribution and features of the margins of the continents. Alyn C. Duxbury Chemical and physical properties of seawater As an excellent starting point for the reader interested in an integrated account of ocean chemistry, physics, and biology, the classic work by H.U. Sverdrup, Martin W. Johnson, and Richard H. Fleming, The Oceans (1942, reissued 1970), is highly recommended. An in-depth, but quite readable, account of the general field of marine chemistry is provided by J.P. Riley and R. Chester, Introduction to Marine Chemistry (1971). Thorough descriptions of each of the many subdisciplines in chemical oceanography can be found in the multivolume work by J.P. Riley and G. Skirrow (eds.), Chemical Oceanography, 2nd ed., including Dana R. Kester, Dissolved Gases Other than CO2, vol. 1, ch. 8 (1975), pp. 497556, a detailed discussion; P.J. Le B. Williams, Biological and Chemical Aspects of Dissolved Organic Material in Sea Water, vol. 2, ch. 12 (1975), pp. 301363, a good survey; J.D. Burton, Radioactive Nuclides in the Marine Environment, vol. 3, ch. 18 (1975), pp. 91191; and Kenneth W. Bruland, Trace Elements in Sea-water, vol. 8, ch. 45 (1983), pp. 157220, a readable account. The Sea, vol. 1, Physical Properties of Sea-water, ed. by M.N. Hill (1962), contains information on all aspects of the behaviour of seawater with changes in temperature, pressure, and salt content, including discussions of density, transmission of light and sound, and sea ice properties. Rhodes W. Fairbridge (ed.), The Encyclopedia of Oceanography, (1966), contains many useful entries on this topic, among them Robert Gerard, Salinity in the Ocean, pp. 758763, discussing spatial and temporal trends of the ocean's salinity and the processes that control it; and J. Lagrula, Hypsographic Curve, pp. 364366, explaining the use of hypsometry and giving the hypsometry of the oceans and their subdivisions. H.W. Menard and Stuart M. Smith, Hypsometry of Ocean Basin Provinces, Journal of Geophysical Research, 71(18):43054325 (September 1966), is also useful. Alyn C. Duxbury Robert Howard Byrne Circulation of the ocean waters Useful books include those by Open University Oceanography Course Team, Ocean Circulation (1989); George L. Pickard and William J. Emery, Descriptive Physical Oceanography: An Introduction, 5th enlarged ed. (1990); Stephen Pond and George L. Pickard, Introductory Dynamical Oceanography, 2nd ed. (1983); Henry Stommel, A View of the Sea (1987); and Henry Stommel and Dennis W. Moore, An Introduction to the Coriolis Force (1989). The following journal articles are also of use: James F. Price, Robert A. Weller, and Rebecca R. Schudlich, Wind-driven Ocean Currents and Ekman Transport, Science, 238:15341538 (Dec. 11, 1987); W.D. Nowlin, Jr. and J.M. Klinck, The Physics of the Antarctic Circumpolar Current, Reviews of Geophysics and Space Physics, 24(3):469491 (1986); and Bruce A. Warren, Deep Circulation of the World Ocean, in Bruce A. Warren and Carl Wunsch (eds.), Evolution of Physical Oceanography (1981), pp. 641. Arnold L. Gordon Waves of the sea Books discussing waves and tides include Open University Oceanography Course Team, Waves, Tides, and Shallow-water Processes (1989); Albert Defant, Ebb and Flow: The Tides of Earth, Air, and Water (1958; originally published in German, 1953); Blair Kinsman, Wind Waves: Their Generation and Propagation on the Ocean Surface (1965, reprinted 1984); M. Grant Gross, Oceanography, 5th ed. (1990), ch. 8, Waves, and ch. 9, Tides, pp. 193241; and David T. Pugh, Tides, Surges, and Mean Sea-level (1987). C. Garrett and W. Munk, Internal Waves in the Ocean, Annual Review of Fluid Mechanics, vol. 11, pp. 339369 (1979), is also of interest. Arnold L. Gordon Density currents in the oceans H.W. Menard, Turbidity Currents, ch. 9 in his Marine Geology of the Pacific (1964), pp. 191222, provides a review of turbidity currents, written from the point of view of marine geology. A.H. Bouma and A. Brouwer (eds.), Turbidities (1964), is a symposium with an extensive bibliography on sediments deposited by turbidity currents. More recent studies include Gerard V. Middleton and Monty A. Hampton, Subaqueous Sediment Transport and Deposition by Sediment Gravity Flows, ch. 11 in Daniel Jean Stanley and Donald J.P. Swift (eds.), Marine Sediment Transport and Environmental Management (1976), pp. 197218, which describes and discusses turbidity currents, grain flows, fluidized sediment flows, and debris flows; Gary Parker, Yusuke Fukushima, and Henry M. Pantin, Self-accelerating Turbidity Currents, Journal of Fluid Mechanics, 171:145181 (1986); and Richard J. Seymour, Nearshore Auto-suspending Turbidity Flows, Ocean Engineering, 13(5):435447 (1986). Gerard V. Middleton The Editors of the Encyclopdia Britannica Impact of ocean-atmosphere interactions on weather and climate Overviews of the general relationship between air and ocean may be found in A.H. Perry and J.M. Walker, The Ocean Atmosphere System (1977); Adrian E. Gill, Atmosphere-Ocean Dynamics (1982); and Neil Wells, The Atmosphere and Ocean: A Physical Introduction (1986).Seasonal and interannual ocean-atmosphere interactions are discussed by C.K. Folland, T.N. Palmer, and D.E. Parker, Sahel Rainfall and Worldwide Sea Temperatures, 190185, Nature, 320:602607 (April 17, 1986); John M. Wallace and Quanrong Jiang, On the Observed Structure of the Interannual Variability of the Atmosphere/Ocean Climate System, in Howard Cattle (ed.), Atmospheric and Oceanic Variability (1987), pp. 1743; T.N. Palmer and Sun Zhaobo, A Modelling and Observational Study of the Relationship Between Sea Surface Temperature in the North-west Atlantic and the Atmospheric General Circulation, Quarterly Journal of the Royal Meteorological Society, 111(470):947975 (October 1985); Jerome Namias, Negative Ocean-Air Feedback Systems Over the North Pacific in the Transition from Warm to Cold Seasons, Monthly Weather Review, 104(9):11071121 (September 1976); and R.E. Davis, Predictability of Sea Level Pressure Anomalies Over the North Pacific Ocean, Journal of Physical Oceanography, 8(2):223246 (March 1978).The formation of tropical cyclones is analyzed in William M. Gray, Hurricanes: Their Formation, Structure, and Likely Role in the Tropical Circulation, in D.B. Shaw (ed.), Meteorology Over the Tropical Oceans (1979), pp. 155218; J.F. Price, Upper Ocean Response to a Hurricane, Journal of Physical Oceanography, 11(2):153175 (February 1981); D.A. Brooks, The Wake of Hurricane Allen in the Western Gulf of Mexico, Journal of Physical Oceanography, 13(1):117129 (January 1983); and Guy A. Franceschini and Sayed Z. El-Sayed, Effect of Hurricane Inez (1966) on the Hydrography and Productivity of the Western Gulf of Mexico, The German Hydrographic Journal, 21(5):193202 (1968).The Gulf Stream and Kuroshio systems are described in Henry Stommel, The Gulf Stream: A Physical and Dynamical Description, 2nd ed. (1965, reissued 1976); William H. MacLeish, The Gulf Stream (1989), including a maritime history of the current as well as scientific data; N.P. Fofonoff, The Gulf Stream, in Bruce A. Warren and Carl Wunsch (eds.), Evolution of Physical Oceanography (1981), pp. 112139; and Henry Stommel and Kozo Yoshida (eds.), Kuroshio: Physical Aspects of the Japan Current (1972). More in-depth essays include Henry Stommel, Asymmetry of Interoceanic Fresh-water and Heat Fluxes, Proceedings of the National Academy of Science of the United States of America, 77(5):23772381 (May 1980); Carl Wunsch, The Ocean Circulation in Climate, in John T. Houghton (ed.), The Global Climate (1984); and Alan R. Robinson (ed.), Eddies in Marine Science (1983).Studies of the El Nio/Southern Oscillation phenomena and their effect on climatic change are found in P.W. Glynn (ed.), Global Ecological Consequences of the 198283 El Nino-Southern Oscillation (1990); S. George Philander, El Nio, La Nia, and the Southern Oscillation (1990); Warren S. Wooster and David L. Fluharty (eds.), El Nio North: Nio Effects in the Eastern Subarctic Pacific Ocean (1985); Richard T. Barber and Francisco P. Chavez, Biological Consequences of El Nio, Science, 222(4629):12031210 (Dec. 16, 1983); Thomas Y. Canby, El Nio's Ill Wind, National Geographic, 165(2):144183 (February 1984); M.A. Cane, El Nio, Annual Review of Earth and Planetary Sciences, 14:4370 (1986); David B. Enfield, El Nio, Past and Present, Reviews of Geophysics, 27(1):159187 (1989); Nicholas E. Graham and Warren B. White, The El Nio Cycle: A Natural Oscillator of the Pacific Ocean-Atmosphere System, Science, 240:12931302 (June 3, 1988); S. George Philander and E.M. Rasmusson, The Southern Oscillation and El Nio, Advances in Geophysics, vol. 28, part A, pp. 197215 (1985); and E.M. Rasmusson, El Nio and Variations in Climate, American Scientist, 73(2):168177 (MarchApril 1985). In addition, the entire issue of Oceanus, vol. 27, no. 2 (Summer 1984), is devoted to El Nio studies. Neil C. Wells David B. Enfield Ocean basins Overviews of the geologic features of the deep-sea floor are given in James P. Kennett, Marine Geology (1982); and Alan E.M. Nairn and Francis G. Stehli (eds.), The Ocean Basins and Margins, 7 vol. in 9 (197388). Specific topics and geographic areas are studied by Roger L. Larson and Walter C. Pitman III, World-wide Correlation of Mesozoic Magnetic Anomalies, and Its Implications, Geological Society of America Bulletin, 83(12):36453661 (December 1972); Ken C. MacDonald and Bruce P. Luyendyk, The Crest of the East Pacific Rise, Scientific American, 244(5):100116 (May 1981); Arthur D. Raff and Ronald G. Mason, Magnetic Survey off the West Coast of North America, 40 N. Latitude to 52 N. Latitude, Geological Society of America Bulletin, 72(8):12671270 (August 1961); H.W. Menard, The Deep-ocean Floor, Scientific American, 221(3):126142 (September 1969); B. Parsons and J.G. Sclater, An Analysis of the Variations of Ocean Floor Bathymetry and Heat Flow, Journal of Geophysical Research, 82(5):803827 (1977); C.M. Powell, S.R. Roots, and J.J. Veevers, Pre-breakup Continental Extension in East Gondwanaland and the Early Opening of the Eastern Indian Ocean, Tectonophysics, 155:261283 (1988); David B. Rowley and Ann L. Lottes, Reconstructions of the North Atlantic and Arctic: Late Jurassic to Present, Tectonophysics, 155:73120 (1988); T. Simkins et al., (1989); and two essays in E.L. Winterer, Donald M. Hussong, and Robert W. Decker (eds.), The Eastern Pacific Ocean and Hawaii (1989), vol. N of the series The Geology of North America: Tanya Atwater, Plate Tectonic History of the Northeast Pacific and Western North America, ch. 4, pp. 2172; and Ken C. MacDonald, Tectonic and Magnetic Processes on the East Pacific Rise, ch. 6, pp. 93110. Bruce Peter Luyendyk Continental margins Francis P. Shepard, Submarine Geology, 3rd ed. (1973), is somewhat dated but still considered by many marine geologists to contain the best treatment of continental margins; many people, however, consider the second ed. (1963) to be more general and better-organized. Elizabeth K. Berner and Robert A. Berner, The Global Water Cycle: Biochemistry and Environment (1987), contains much information on the contribution that rivers make to margin sediments. Creighton A. Burk and Charles L. Drake (eds.), The Geology of Continental Margins (1974), contains a general section on continental margins and many chapters on the details of specific margins, written for the advanced student. Francis P. Shepard and Robert F. Dill, Submarine Canyons and Other Sea Valleys (1966), is the most complete treatment of submarine canyons in one volume, written in a style easily grasped by high school as well as advanced students. Larry J. Doyle and Orrin H. Pilkey (eds.), Geology of Continental Slopes (1979); and K.O. Emery, The Continental Margins, Scientific American, 221(3):106122 (September 1969), are also useful. Larry James Doyle Coastal and nearshore features General discussions may be found in Eric C.F. Bird, Coasts: An Introduction to Coastal Geomorphology, 3rd ed. (1984); J.L. Davies, Geographical Variation in Coastal Development, 2nd ed. (1980); and Maurice L. Schwartz (ed.), The Encyclopedia of Beaches and Coastal Environments (1982).Further information on coral reefs can be found in Charles Darwin, The Structure and Distribution of Coral Reefs (1842, reissued 1984); J.A. Fagerstrom, The Evolution of Reef Communities (1987); and Andr Guilcher, Coral Reef Geomorphology (1988). For more detailed information on the Great Barrier Reef and coral reef devastation, respectively, see W.G.H. Maxwell, Atlas of the Great Barrier Reef (1968); David Hopley, The Geomorphology of the Great Barrier (1982); Charles Birkeland, The Faustian Traits of the Crown-of-Thorns Starfish, American Scientist, 77(2):154163 (MarchApril 1989); and E.H. Williams, C. Goenaga, and V. Vincente, Mass Bleachings on Atlantic Coral Reefs, Science, 238:877878 (Nov. 13, 1987).Various aspects of lagoons and estuaries are dealt with in K.H. Mann, Ecology of Coastal Waters (1982); George H. Lauff (ed.), Estuaries (1967); Bjrn Kjerfve (ed.), Hydrodynamics of Estuaries, 2 vol. (1988); Stephen P. Leatherman, Barrier Island Handbook, 3rd ed. (1988); and T.E. Pickett and R.L. Ingram, The Modern Sediments of Pamlico Sound, North Carolina, Southeastern Geology, 11(2):5383 (1969).Particular gulfs and bays are described in Rhodes W. Fairbridge (ed.), The Encyclopedia of Oceanography (1966); A.J. Huxley (ed.), Standard Encyclopedia of the World's Oceans and Islands (1962); and Eric C.F. Bird and Maurice L. Schwartz (eds.), The World's Coastline (1985). Maurice L. Schwartz Economic aspects of the oceans An entire issue of Oceanus, vol. 21, no. 4 (Winter 1984/85), is devoted to the impact of the Exclusive Economic Zone, especially as it pertains to the United States; coastal fishing, multiple-use management, marine pollution, and nonliving resources are some of the topics covered. Giulio Pontecorvo, The New Order of the Oceans: The Advent of a Managed Environment (1986), deals with the new ocean regime and with the research and technology of marine resources from a global perspective, particularly emphasizing the international effects of the 1982 United Nations Law of the Sea Convention. The evolution of international marine policy and shipping law is compellingly discussed in Edgar Gold, Maritime Transport (1981), and Ocean Shipping and the New Law of the Sea: Toward a More Regulatory Regime, Ocean Yearbook, vol. 6, pp. 8596 (1986).Discussions of the managed production of aquatic organisms include J.F. Muir, AquacultureTowards the Future, Endeavour, 9(1):5255 (1985); and John Bardach, Aquaculture: Moving from Craft to Industry, Environment, 30(2):611, 3641 (March 1988). Desalinization processes are discussed and illustrated in Alan D.K. Laird, The Potable Sea: Taking the Salt from Saltwater, Oceans, 15(5):2529 (SeptemberOctober 1982); and Roberta Friedman, Salt-free Water from the Sea, Sea Frontiers, 36(3):4954 (MayJune 1990).Overviews of various ocean energy resources and technologies may be found in Maxwell Bruce, Ocean Energy: Some Perspectives on Economic Viability, Ocean Yearbook, vol. 5, pp. 5878 (1985); and Terry R. Penney and Desikan Bharathan, Power from the Sea, Scientific American, 256(1):8692 (January 1987). Tidal power generation is covered by B. Count (ed.), Power from Sea Waves (1980), based on conference proceedings; and Michael E. McCormick, Ocean Wave Energy Conversion (1981). Summaries of ocean thermal energy conversion techniques and future prospects are provided by R. Cohen, Energy from the Ocean, Philosophical Transactions of the Royal Society of London, Series A, 307:405437 (1982); and D.E. Lennard, Ocean Thermal Energy ConversionPast Progress and Future Prospects, IEE Proceedings, vol. 134, part A, no. 5, pp. 381391 (May 1987).Current and future petroleum and mineral resources in the ocean environment and the technologies necessary to recover them are addressed in Gerard J. Mangone (ed.), The Future of Gas and Oil from the Sea (1983); Elisabeth Mann Borgese, The Mines of Neptune: Minerals and Metals from the Sea (1985); David Cronan, A Wealth of Sea-floor Minerals, New Scientist, 106:3438 (June 6, 1985); and James M. Broadus, Seabed Materials, Science, 235:853860 (Feb. 20, 1987). Discussions of the use of the ocean as a site for waste disposal, and the problems of marine pollution, include Iver W. Duedall et al. (eds.), Wastes in the Ocean, 6 vol. (198385), on industrial and sewage, radioactive, and energy wastes, dredged-material disposal, and deep-sea and nearshore waste disposal; R.B. Clark, Marine Pollution, 2nd ed. (1989); Wesley Marx, The Oceans: Our Last Resource (1981); David K. Bulloch, The Wasted Ocean (1989); and a complete issue of Oceanus, vol. 33, no. 2 (Summer 1990). The Editors of the Encyclopdia Britannica

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