Hydrogeochemical Assessment of Heavy Metal Contamination and Groundwater Quality in the Vicinity of A Landfill Site in Rumuola, Obio/Akpor, Rivers State, Nigeria

Rapid urbanization and indiscriminate wastes disposal in the peri-urban environments of the Niger Delta have created a serious concern about the quality of shallow aquifer systems, which are sources of potable water for poor and marginalized communities in the area without access to treated public water supplies. In this study, a hydrogeochemical approach was employed to evaluate the quality of groundwater and surface water in Rumuola, Obio/Akpor Local Government Area, Rivers State, Nigeria, with specific focus on the potential impacts of a stagnant water body resulting from a landfill on the physicochemical and heavy metal constituents of underlying borehole aquifers in the study area. A total of eight borehole sites were surveyed, and water samples were collected from the stagnant water body, operational boreholes, and a bottled water sample as a control. Water samples were subjected to analyses for pH, electrical conductivity (EC), total dissolved solids (TDS), turbidity, total suspended solids (TSS), sulphate, nitrate, phosphate, biochemical oxygen demand (BOD), chemical oxygen demand (COD), and ten heavy metals, namely, Manganese (Mn), Zinc (Zn), Lead (Pb), Cadmium (Cd), Nickel (Ni), Chromium (Cr), Sodium (Na), Potassium (K), Calcium (Ca), and Magnesium (Mg). The direction of the groundwater flow was determined using the hydraulic head analysis of the water table using Surfer 8 software. It was observed that the groundwater flow direction lies in the south to south-east direction. It was also observed that the concentration of the analyzed heavy metals present in the groundwater samples was below the permissible limits of the World Health Organization (WHO) for water meant for human consumption. However, the stagnant water body recorded a high level of turbidity at 15.20 NTU, a high level of COD at 57.60 mg/L, and a high EC level at 186.00 µS/cm compared to the groundwater samples. It was also observed that the groundwater quality lies within the acceptable limits using pollution indices such as the Heavy Metal Pollution Index (HPI) and the Contamination Factor (CF) for the groundwater samples, whereas the stagnant water body recorded a moderate level of heavy metal concentration. These results serve as a precursor to the environmental monitoring program to be conducted in the near future in the Niger Delta area, which is undergoing rapid urbanization.