Dissolved oxygen dynamics in a facultative pond.

Abstract

The dynamics and distribution of dissolved oxygen along the length and depth of a facultative waste stabilization pond is presented in this article. Measurements of dissolved oxygen were performed on field with a frequency of two hours at the inlet, center and outlet of the pond three depths (surface, center and bottom). In addition, measurements were made in the center of the pond by dividing it into 0.10 m intervals to obtain profiles of dissolved oxygen at different times of the day. The results obtained from Pearson correlations on the inlet-center, outlet-center and inlet-outlet were representative for surface data with correlation coefficients greater than 0.90, unlike for depths at 0.75 m and 1.50m were a maximum correlation coefficient of 0.30 was obtained. The concentration of dissolved oxygen on the surface through the time has asinusoidal behavior, were at 6:00 hours the concentration of dissolved oxygen is almost null, and then increases up to reach values around 20 mg/l at 14:00 hours and after this, it starts to decrease to values around 4 mg/l at 20:00 hours. The dissolved oxygen profiles showed a clear stratification and slight mixing, concluding that the photosynthetic activity is developed in the first 0.30 m of pond’s depth, in the photic zone.