A low DO value in the rainy season resulted from
high levels of organic matter mineralization, which was
indicated by a high BOD5. The decomposition of organic
matter consequently increased the CO2 values in
the water body and likely decreased the pH in the rainy
season. Dunbabin and Bowmer (1992) reported patterns
of metal removal in water with higher DO and pH
values, likely as a result of hydrous metal formation.
The alkalinity did not differ between the seasons, and
conductivity was higher in the dry season compared
with the rainy season.