Winkler Titration Assessment of Biochemical Oxygen Demand (BOD5) in Oka Creek, Toru-Orua, Bayelsa State

Abstract

Aim: The aim of study was to investigate the Biochemical Oxygen Demand (BOD) levels in water samples from the Oka Creek. Study Design: Qualitative study design. Place and Duration of Study: Water samples were collected from the Oka Creek, located in Toru-Orua in Sagbama Local Government Area, Bayelsa State, Nigeria. The study lasted for twenty days. Methods: Water samples were collected from four different locations and depths in the Oka Creek, Toru-Orua, Sagbama Local Government Area of Bayelsa State, Nigeria, at various times. Each sample was transferred into 250 ml bottles labeled L1, L2, L3, and L4. The temperatures of the samples were recorded before transporting them to the chemistry laboratory for treatment.  Winkler titration method was employed in analyzing the samples. Results: Location L1 recorded the highest BOD value, 28.38 mg/L, measured at sunset (25 °C), from a relatively stagnant region. The high BOD at this location is attributed to minimal photosynthetic activity and significant oxygen consumption by microorganisms. In contrast, L2, collected from the same region at 35 °C during peak sunlight, exhibited a BOD value of 21.76 mg/L. The lower BOD at L2 is due to increased photosynthetic activity. These high values suggest significant sludge deposits, domestic sewage and agricultural runoffs, which could lead to oxygen depletion and negatively impact aquatic life. Sample L3, taken from a deeper, stagnant region at sunset (25 °C), recorded a BOD value of 4.50 mg/L. This moderate BOD level suggests the presence of moderate sludge deposits and agricultural runoff, but higher water flow speed helped mitigate these effects. Location L4, with the lowest BOD value of 3.74 mg/L, was collected during peak sunlight (35 °C). Deeper location and high water flow speed contributed to reduced BOD levels, indicating better water quality and a healthier aquatic environment. Conclusion: The BOD values at L1 and L2 (28.38 mg/L and 21.76 mg/L) exceed acceptable limits for fish growth. Conversely, BOD values at L3 and L4 (4.50 mg/L and 3.74 mg/L) fall within acceptable limits, suggesting healthier aquatic environment, as evidenced by the yearly bountiful fish harvests in these sections of the Oka Creek.