Evaluation of the heavy metal pollution index of groundwater in Effutu Municipality,Ghana

Abstract

An assessment of the quality of groundwater in the Effutu Municipality was carried out at six sampling sites in some selected communities in the Effutu Municipality. Samples were collected from November 2020 to May 2021. Analysed various physicochemical parameters including Electrical conductivity, Temperature, pH, Chemical Oxygen Demand (COD). Heavy metals analysed are Cobalt, Zinc, Cadmium, Lead and Iron. Concentrations of the five (5) heavy metals: Cobalt, Zinc, Cadmium, Lead and Iron were determined using Flame Atomic Absorption Spectrophotometer using an air-acetylene oxidizing flame and used to evaluate the heavy metal pollution index (HPI) using two barreled approaches. In the first instance heavy metals that were not detected by the instrument were assigned zero concentration. In the second instance, these heavy metals were assigned the limit of detection from the instrument as if they were present to that extent. The result of the study revealed that, the mean values of the pH and COD of the groundwater at the sampling sites were within the GEPA and WHO permissible limit. However, the Electrical Conductivity exceeds the GEPA and WHO permissible limit at some of the selected groundwater sampling sites. The two HPI computations for not detected (ND) for metals not detected and for the limit of detection of the instrument for metals not detected for the dry season were 0.887 and 0.880 and for the raining season were 0.832 and 0.832. The two approaches used in the computation of HPI for the groundwater based on the mean concentrations of the selected heavy metals and the limit of detection from the instrument gave similar results. The near sameness of these values indicates that both approaches could be used to calculate the HPI. There was a significant correlation (P<0.01) between the two HPI’s. The study clearly indicates that, the selected groundwater sites in the Effutu Municipality monitored to be free from the selected heavy metals and can therefore be used for human consumption.