Anthropogenic Impacts on Physicochemical and Heavy Metal Concentrations of Ogbor Hill River Water, Southern Nigeria

The present study assessed the effects of human pressure on the surface water quality of the Ogbor Hill River, southern Nigeria. This river is among one of the important rivers in Southeast Nigeria for domestic, agricultural and industrial purposes. To assess the water quality, samples of water were collected monthly for eight months, and were preserved and transferred to the laboratory for further analysis. Electrical conductivity, pH, total dissolved solids, salinity, turbidity and temperature were determined in situ. Other parameters were determined in the laboratory using standard laboratory methods. The results revealed that the mean pH was acidic across the months with no significance difference (p > 0.05). Additionally, the mean total dissolved solids showed a significant difference (p < 0.05), with a higher value of 582.10 +/- 83.41 in April and a lower value of 243.67 +/- 40.62 in May. The highest mean conductivity of 1392.33 +/- 156.18 was observed in April, and the lowest mean of 289.33 +/- 97.37 in May. Dissolved oxygen indicated there was a significant difference among the study months (p < 0.05), with the highest mean concentration of 4.80 +/- 0.37 in June and the least of 3.30 +/- 0.20 in April. Biochemical oxygen demand, chloride and temperature all showed a significant difference (p < 0.05) across the sampling months. The mean concentration of Zn showed no significant difference among the study months. The mean concentration of Fe recorded showed the highest value of 2.68 +/- 0.16 in April and the lowest mean of 1.96 +/- 0.13 in July. Pb showed a higher concentration of 0.44 +/- 0.33 in March and a lower mean of 0.033 +/- 0.008 in July. A higher mean Cd of 0.052 +/- 0.004 was observed in March and a lower mean of 0.023 +/- 0.002 in December. Generally, the water parameters were elevated beyond the threshold for surface water, which was an indication that the river water was badly impacted due to human pressure and needed to be kept safe for human use. The present study revealed that most of the water quality parameters such as TDS, DO, BOD, pH, turbidity, and concentrations of the heavy metals Pb and Cd were higher in selected months, and further water management should be carried out while anthropogenic activities should be reduced around the river ecosystem.