This work quantitatively evaluates the level and
impact of selected physiochemical properties of fertilizer effluent on the
Obinna River of Adani, Enugu State, Nigeria. The fertilizer effluent originated
from surrounding farms and flushed into the Obinna River. Water samples were
collected from designated points along the river and analysed for physical,
chemical and biological properties using standard methods of APHA. Impact of
selected key parameters such as nitrate, phosphate, manganese, dissolved
oxygen, biochemical oxygen demand and heavy metals (lead, iron and manganese), was
studied. The results of the parameters were compared with the World Health
Organisation (WHO) permissible standard for freshwater. Measured concentrations
of phosphate (5.00, 7.21, 3.92 mg/L), manganese (1.53, 1.18, 1.47 mg/L) and
lead (18.9, 21.7, 39.7 ppm) were found to be above the WHO standard while
nitrate (0.04, 0.03, 0.03 mg/L) and iron (0.001, 0.001, 0.1 mg/L) were within
the standard. The mean concentrations of heavy metals increased in the
following order: Fe (0.034) < Mn (1.4) < Pb (26.8) from upstream S1 to downstream S3, with manganese and lead being above WHO standard.
The results showed a level of significance for the chi-square distribution and
correlation coefficients while the analysis of variance (ANOVA) results was
conflicting. It could be inferred that the impact of the selected parameters
contributed to the pollution of Obinna River.