X 



o 



o 





O 



>- 

 X 



o 



o 

 to 



60- 

 50 - 

 UO — 

 30 - 



20 — 

 10 — 



6 



NOV. 19, 1958 



NOV. lU. 1958 



8 



12 



U 

 AM 



6 



Dl 



URNAL VARIATION IN DISSOLVED OXYGEN IN A SEWAGE STABILIZATION POND 



LEBANON. OHIO 

 Figure 2 



AM 



PM 



AM 



DIURNAL VARIATION IN DISSOLVED OXYGEN IN TWO OHIO RIVERS 



Fiflure 3 



300 foot-candles: 2.8 ppm. algae produced 3.4 

 ppm. oxygen; 11.0 ppm. algae produced 7.9 ppm. 

 oxygen; and 13.7 ppm. algae produced 18.4 ppm. 

 oxygen . It was also noted that oxygen production 

 in relation to algal density, expressed as sus- 

 pended solids, increased as samples were col- 

 lected progressively downstream. Concurrently, 

 the blue-green planktonic algae from Lake Winne- 

 bago, from which the Fox River flows, were re- 

 placed by algae more suited to the flowing water 

 habitat. How the laboratory results are to be ap- 

 plied to river conditions was not determined. 



A third approach used the "light and dark 

 bottle test" to measure photosynthesis and respira- 

 tion simultaneously. Although raw sewage stabi- 

 lization ponds are not natural waters, the intensity 

 of processes occurring there makes studying them 

 especially instructive in relation to other waters. 

 In general essentially all photosynthesis occurs in 

 the surface water layer that absorbs 99% of the 



light. For this reason water transparency must 

 serve as a guide in determining desirable depths at 

 which to expose light and dark bottles within the 

 euphotic zone . Typical relations between oxygen 

 production and oxygen use in such ponds are shown 

 in Figure 7 . During mid-morning with intense light 

 and abundant carbon dioxide accumulated during 

 nocturnal bacterial decomposition, photosynthetic 

 oxygen production reaches a high rate of more than 

 2 grams per square meter per hour. At the depth 

 where light intensity is 20% of the surface value, 

 oxygen production proceeds at 70 times the rate 

 found at only 1% of surface value intensity. Be- 

 cause the density of phytoplankton is much greater 

 than that commonly found in other surface waters , 

 extinction of light is rapid and the euphotic zone 

 is only about 120 centimeters thick. In the Ohio 

 River, on the other hand, turbidity is caused 

 largely by inorganic suspensoids, but they are suf- 

 ficient to absorb 99% of the light in about 130 



59 



