Dissolved Organic Carbon as a Controlling Factor in Oxygen Consumption in Natural and Man-made Waters

Abstract

The rate of oxygen (O2) consumption Y (mg O2/l.hr), as well as the amount of dissolved organic carbon (DOC) X (mg C/l), in a sample water showed almost no variation in the middle period of aerobic incubation at 25°C. The rates Y in this period were highly correlated with the amount X (Y=3.29x10-3 X1.50; correlation coefficient r, 0.970) among the forty-six sample waters from various sources including rivers, ponds, ground waters, activated sludges and others. Assuming that DOC is the respiratory substrate for the aquatic microbes, the turnover rate of DOC per hour was calculated to be the highest of 0.0194 (retention time t, 51.6 hrs) in the activated sludge which had been decomposing coke-oven liquors, and the lowest of 0.00093 (t, 1,075 hrs) in the hot spring of Izu Peninsula. Considering the large differences in the turnover rate among the forty-six sample waters, the possible ecological significance and problem of DOC were discussed for the comprehension of the microbial metabolism in the waters. © 1982, The Japanese Society of Limnology. All rights reserved.