Evaluation of cycling patterns of dissolved oxygen in a tropical lake as an indicator of biodegradable organic pollution

Dissolved oxygen cycling patterns in a tropical lake Weija Lake. were shown to be useful as a potential indicator of biodegradable organic pollution, by dosing with liquid malt to give an additional organic burden of 2.5 and 5.0 mg ly1 TOC, and monitoring the DO values continuously for 140 h. These loadings were added to water columns in tubes. suspended from a raft in a lake in south-east Ghana. The addition of organic pollution burden to the lake water produced two main effects: the mean DO value was lowered, and the amplitude of the DO cycle decreased as organic loading increased from 2.5 to 5.0 mg ly1 TOC. There was also an indication of heterotrophic respiration associated with organic inputs for the 5.0 mg ly1 added TOC suggesting a PrR ratio of well below 1.0. Taking the results of a DO cycling computer model together with those from the lake raft experiments, it can be concluded that dissolved oxygen cycles can be a good indicator of biodegradable organic pollution load.