PHYSICO-CHEMICAL DYNAMICS OF OWENA RIVER AND RESERVOIR, ONDO STATE, NIGERIA

1Olaniyan, R.F, and 2Oguntimehin, P.

1Department of Biology, 2Department of Chemistry

Adeyemi College of Education, Ondo, Ondo State

Author’s Email;olaniyan4real_06@yahoo.com

                                        G.S.M NO; +2348060083658                                                  patrick.oguntimehin@gmail.com G.S.M NO; +2348034809269

 

ABSTRACT

          Owena Reservoir was established along Owena River primarily to supply water to Ondo and Akure towns during the dry season. The river receives domestic wastes such as faeces, laundry wastes and cassava peels, while run-offs from chemically sprayed agricultural farms enter into the reservoir. Despite increasing anthropogenic activities in the river and reservoir, there is dearth of information on their limnology. The aim of this study was to investigate the physico-chemical characteristics of Owena River and Reservoir in order to provide information for effective management.

Monthly sampling was carried out from nine randomly selected sites on Owena River (6) and Reservoir (3) from June 2013 to July 2015. Water temperature was measured in situ. Conductivity, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), pH and alkalinity were determined from collected surface water according to APHA methods.  Data were analysed using descriptive statistics, Pearson correlation coefficient and ANOVA.

Mean temperature, conductivity, DO, BOD, pH and alkalinity were 27.6 °C ± 3.3°C, 116.3 ± 2.0 μScm-1 , 6.3 ± 1.2 mg/L, 3.0±0.8 mg/L, 7.3± 0.1 and 12.0 ± 2.9 mg/L respectively for the river, while, the values recorded for the reservoir were 28.2 °C ± 1.3 °C, 127.2 ± 16.9 μScm-1,  6.3 ± 1.2 mg/L,  1.8 ± 0.9 mg/L,  7.2 ± 0.1, 67.7 ± 7.8 mg/L respectively. Water temperature, pH, conductivity, BOD, DO and alkalinity values fell within WHO limits for aquatic life. Water temperature was significantly (p<0.05) correlated with pH (r=0.05), alkalinity (r=0.53) and BOD (r=0.05) are not significantly correlated with conductivity.

The findings suggest that the river is more impacted by anthropogenic activities than the reservoir. There is need for enforcement of management policies against dumping of wastes into the river. The river could be used for aqua cultural practices, but not for drinking.  

 Keywords: Physico-chemical characteristics, Anthropogenic wastes, Owena River and Reservoir.