. Elements of ecology. Ecology. 250 Oxygen and Carbon Dioxide cold water that sinks to great depths may be understood eventually to find its way to the surface again in the central part of the ocean, and a return flow of water from the equatorial regions toward the poles is brought about as a part of the horizontal circulation of the upper water 1000 2000 3000 4000 50no 70° S 60° 50° 40° 30° 20° 10° S 0° N 10° 20° 30° 40° 50° 60°N Fig. Cross section of the Atlantic Ocean, showing the distribution of oxygen in cubic centimeters per liter. The north-south and vertical components of
. Elements of ecology. Ecology. 250 Oxygen and Carbon Dioxide cold water that sinks to great depths may be understood eventually to find its way to the surface again in the central part of the ocean, and a return flow of water from the equatorial regions toward the poles is brought about as a part of the horizontal circulation of the upper water 1000 2000 3000 4000 50no 70° S 60° 50° 40° 30° 20° 10° S 0° N 10° 20° 30° 40° 50° 60°N Fig. Cross section of the Atlantic Ocean, showing the distribution of oxygen in cubic centimeters per liter. The north-south and vertical components of the oceanic currents are indicated by the arrows. (Modified from Sverdrup et al., 1942, after Wiist.) Sea water near the surface in tropical regions contains about 4 cc of oxygen per liter, but as it becomes colder at higher latitudes, oxygen is absorbed from the atmosphere and produced by photo- synthesis until a concentration of about 8 cc per liter is attained. When the water masses leave the surface and sink toward the bottom, depletion of oxygen begins as a result of respiration and decomposi- tion, but as much as 5 cc Oo per liter remains when the water reaches the ocean abyss. Animals living at the bottom of the sea thus receive oxygen via a direct flow of water from the enriched polar seas, but this is perhaps the slowest delivery service in the world. Calculations based on the rate of consumption of oxygen and also on the relative proportion of C14 in deep water indicate that movement of Arctic surface water to deep layers at midlatitudes may require a thousand years or more. The concentration of oxygen at any point in deep water depends upon (1) the amount that the water contained when it left the surface, (2) the rate at which oxygen is used up en route by respira- tion and decomposition, and (3) the time that has elapsed. Mini- mum values occur at positions in the ocean at which the combined effect of the foregoing factors has reduced the oxygen to th
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Keywords: ., bookcentury1900, bookpublishernewyorkwiley, booksubjectecology
