An Evaluation of the Spatial Distributions of the Physico-Chemical and Microbial Contents of Nworie River in Owerri, Southeastern Nigeria

Abstract

Water quality assessment of a tropical river arises due to the importance of such rivers as main sources of water for domestic, agricultural, tourism and industrial purposes. The spatial distribution of the physical, chemical and microbial contents of Nworie River water was assessed to ascertain its suitability for the intended uses. Three sets of eight raw water samples collected at pre-designated points on the river were analyzed using the Atomic Absorption Spectrophotometer (AAS) and flame photometry to determine the concentrations of cations (Ca2+, Mg2+, Fe2+, Na+ and K+) and anions (CO3-, SO42-, Cl- and NO3-). Digital Meters were used to determine pH, conductivity and Total Dissolved Solids, while Standard Plate Counts were employed to ascertain the extent of bacterial loads in the Nworie River water. The results of the analyses indicated that average pH, conductivity and Total Dissolved Solids (TDS) of Nworie River water were 7.00, 22.62 μS/cm and 28.85 mg/l, respectively. Mean concentrations of analyzed cations (Ca2+, Mg2+, Na+ and K+) were 10.23, 7.51, 3.36 and 5.40 mg/l, respectively, while the mean concentrations of analyzed anions (CO3-, SO42-, Cl- and NO3-) were 16.13, 4.48, 5.72 and 5.40 mg/l, respectively. Characterization of the river water, therefore, followed the trend of Ca2+ > Mg2+ > K+ > Na+, for the cations and CO3- > NO3- > Cl- > SO42- for the anions. These trends indicated that Nworie River water is predominantly CaCO3 water. Other physical attributes in terms of odour, however, is satisfactory, while colour and turbidity fell short of the recommended standards for safe drinking water. The coloured and turbid Nworie River water resulted from high concentrations of iron (Fe2+), which ranged from 2.97 - 4.80 mg/l. The Sodium Adsorption Ratio (SAR) of 0.19 is indicative of excellent quality of the river water for irrigation purposes. Bacteriological analysis indicated the dominance of aerobic bacteria and E. coli. Some of the samples collected from other sampling stations however, showed satisfactory counts indicating that bacterial contamination arose from point sources. The generally increased Coliform Counts and high iron contents were the major environmental problems observed in the Nworie River water. These degradations are associated with increased anthropogenic activities on the Nworie River Watershed within the period in focus.