. Elements of ecology. Ecology. 246 Oxygen and Carbon Dioxide How does oxygen get to the bottom of the ocean? We have seen that the sources of oxygen are at or near the surface, but we know that many kinds of aerobic animals live at the bottom of some lakes and in the ocean abyss at depths of several miles beneath the surface. Although oxygen moves slowly through the water by direct diffusion, it can reach the deeper levels at an adequate rate only by the circula- tion of the water itself. 6 pm 12 mid 6 am 12 m 5 pm. Modified from Tressler, Tiffany, and Spencer, 1940 Fig. Diurnal cycle of
. Elements of ecology. Ecology. 246 Oxygen and Carbon Dioxide How does oxygen get to the bottom of the ocean? We have seen that the sources of oxygen are at or near the surface, but we know that many kinds of aerobic animals live at the bottom of some lakes and in the ocean abyss at depths of several miles beneath the surface. Although oxygen moves slowly through the water by direct diffusion, it can reach the deeper levels at an adequate rate only by the circula- tion of the water itself. 6 pm 12 mid 6 am 12 m 5 pm. Modified from Tressler, Tiffany, and Spencer, 1940 Fig. Diurnal cycle of temperature, oxygen, hydrogen ion (as pH), and car- bon dioxide in the surface waters of Buckeye Lake, Ohio, during August 12—13, 1930. Negative values for CO2 represent amount of CO2 required to make v^^ater neutral to phenolphthalein. Oxygen-rich surface water is carried downward by wind stirring, eddy conduction, and mass sinking. Wind stirring is very effective in aerating the upper layers of lakes and of the ocean at times when the water circulates freely. Whenever a water body is covered by ice, no turbulence caused by wind or waves is possible. At other seasons stirring is greatly curtailed whenever the water is stratified in respect to density—as a result of salinity differences occurring at any time of year, or as a result of a thermal gradient arising primarily in summer. During periods of pronounced stratification the circula- tion produced by wind and waves is limited to the layers above the density discontinuity (Fig. ). When stratification has been de-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Clarke, George L. (George Leonard), 1905-. New York, Wiley
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