Hydrogeochemical and microbial constituents of groundwater in Lephalale municipality, Limpopo province, South Africa

Abstract

This study assessed the hydrogeochemical characteristics and microbial constituents of groundwater in Lephalale Municipality, South Africa. A total of 71 borehole water samples were collected from 15 villages within the Lephalale Municipality between April 2019 and October 2020. The results of the parameters such pH, EC, TDS, and alkalinity range from 6.69 to 7.87, 620.30 to 1937.00 μS/cm, 330.35 to1035.50 mg/L and 50.00-390.00 mg/L, respectively. The mean values of major cations and anions were found to be in the order of Na+>Ca2+>Mg2+>K+ and HCO3−>Cl−>NO3−>SO42−>F−, respectively. About 35 % of the tested samples had F− concentrations above 1.5 mg/L recommended by the world health organization (WHO) to eliminate the risk of fluorosis. The hydrogeochemical facies determined using a piper diagram revealed the dominance of mixed CaMgCl and CaHCO3 water types. The Gibbs plot analysis revealed that the main composition-controlling hydrogeochemical processes in the study area is the rock-water interaction. The microbial constituent's analysis showed that faecal coliform in groundwater samples were ranging between 0 and 71 CFU/ 100 mL with an average of 0.56 CFU/100 mL, while total coliform (TC) counts were between 0 and 360.5 CFU/100mL with the average of 30.81 CFU/100mL, respectively. This study revealed that groundwater in some boreholes from Lephalale Municipality poses risk of fluorosis and pathogen related diseases. Therefore, the study recommends improving of water quality within the study area prior to consumption.