Abstract
By the use of the 15N tracer technique, the relationship between the quality of water or the bacterial flora in aquatic environments and the metabolic rate of ammonium nitrogen was studied in a fish culturing pond and in experimental aquaria with and without aeration.
The turnover rate of ammonium nitrogen in the water was estimated to be 2.9%/h in the pond; 4.5%/h and 0.6%/h were the rates in the aerated aquarium and the stationary aquarium, respectively. It became evident that the metabolic rate of nitrogenous compounds is reflected in the water quality. A high rate of ammonia oxidation was observed in the water bodies with high DO levels, while the process of denitrification proceeded more rapidly in the water which contained a large amount of organic matter than in the water which lacked sufficient dissolved oxygen.
