Assessment of the impact of onsite sanitary sewage system and agricultural wastes on groundwater quality in Ikem and its environs, south-eastern Nigeria

Physicochemical, multivariate, and bacteriological analyses were integrated to assess the impact of onsite sanitary sewage and agricultural waste on groundwater quality in Ikem and its environs. Results of the physicochemical analysis suggest that groundwater samples in the study area are acidic, with very few samples having electrical conductivity and total dissolved solids above WHO standard for drinking water. The abundance of the major ions are in the following order: Ca 2+ ˃Mg 2+ ˃K + ˃Na + ˃ Cl − = PO 4 2- ˃NO 3 − ˃HCO 3 − ˃SO 4 2- . Fifty-five percent of the stiff plot shows Ca 2+ - Cl − water type and 45% of the stiff shows Na + + K + - Cl − water type. The dominant hydrochemical facies in the study area are Ca 2+ -Mg 2+ -Cl − SO 4 2- (83%) and Na + + K + and SO 4 2- + Cl − (17%). Durov and Piper diagrams illustrated that simple mineral dissolution and ion exchange processes are mainly responsible for variation in the hydrogeochemistry. Bacteriological analysis shows that the groundwater is contaminated with faecal waste. The principal component analysis, correlation, and cluster analysis reflect Faecal matter contamination through onsite sanitary sewage system, leaching of agricultural waste into the groundwater and weathering and dissolution of host rocks. Groundwater flow direction is local and controlled by topographic highs, weathering and fracturing of the host rock in the study area.