Characterization of tropical freshwater; River Ogun, Lagos Nigeria

Abstract

Physico-chemical parameters and microbial contents of Ogun River at Magodo area, Lagos were investigated in relation to its safety for consumption. Water samples were weekly collected between August and December, 2016 at three equi-distance intervals for analysis on physico-chemical parameters, total bacterial count and biochemical tests following standard recommended procedures. Mean concentrations of the physico-chemical parameters were found in ranges for pH (6.68 ± 0.15 - 6.86 ± 0.21), temperature (26.78 ± 0.14 – 26.92 ± 0.31), electrical conductivity (355.40 ± 101.93 – 456.40 ± 115.77), total dissolved solids (166.80 ± 48.08 - 215.00 ± 54.29), dissolved oxygen (7.06 ± 0.01 - 7.08 ± 0.02), biochemical oxygen demand (25.59 ± 0.03 - 25.64 ± 0.01), chemical oxygen demand (98.75 ± 0.03 - 98.84 ± 0.02), total hardness (345.80 ± 1.28 - 349.40 ± 3.87), total alkalinity (9.28 ± 0.02 - 9.33 ± 0.02), nitrate (0.27 ± 0.00 - 0.28 ± 0.00), sulphate (0.55 ± 0.05 - 0.62 ± 0.00) and chloride (68.84 ± 0.77 - 74.97 ± 1.23). Total colony forming unit (Cfu) of bacteria in the river was found highest in descending order Centrimide Agar (CA) > Mac-Conkey Agar (MCA) > Plate Count Agar (PCA) > Mannitol Salt Agar (MSA) at the first and second serial dilution respectively. Biochemical tests showed the presence of Staphylococcus species, Escherichia coli, Pseudomonas aeruginosa, Proteus sp., Salmonella sp. and Baccillus sp. in the river. Variations in the microbial load and physico-chemical parameters in Ogun River as a result of different human activities around the river was found within the standard limits which makes the River safe for human consumption.

Key words: River Ogun, microbial load, bacterial count, biochemical tests Trop.