ABSTRACT
The analysis of changes in water quality in a monitoring network system is important because the source of pollution vary in time and space. We investigated the physical and chemical properties of Okhuaihe River, Okeze, Edo State, Nigeria. Surface water samples are collected seasonally in four selected sites along the water course of the Okhuaihe River from January and February (dry season) and April (wet season), 2021. Twenty-three physical and chemical variables namely, water temperature (WT), air temperature (AT), water level (WL), transparency (Transp.), flow velocity (FV), pH, total dissolved solid (TDS), electric conductivity (EC), DO, BOD5, turbidity (turb), phosphate, nitrate, sulphate, lead, nickel, manganese, zinc, cadmium, chromium, cobalt and copper were analyzed using standard methods. Four physical and chemical variables namely, turbidity (5.24NTU), pH (5.2), Cu (0.33mg/L) and Zn (0.39mg/L) were above world Health Organization (WHO)/ Nigeria Industrial Standard (NIS) guidelines. There was statistically significant difference (p< 0.05) in the spatial variation of 9 variables. Five parameters, names, WL, NO3-N, SO4, Co and Mn differ significantly (p< 0.05) between dry and wet season. There was strong positive correlation between (turb and WT, r = 0.66), (WL and AT, r = 0.89), (transp. and WL, r = 0.99), (turb. and WL, = 0.88) and (NO3-N and WL = 0.86). Overall, water quality index (WQI) suggests that site 1 (reference) had the best water quality followed by site 2, followed by site 3 and 4, respectively. We recommend routine monitoring of the water quality of Okhuaihe River as it serves various purpose to its inhabitant.
