Hydrogeochemical Evaluation of Groundwater Quality in Auchi and Its Environs

Abstract

The quality of groundwater is determined by its physical, chemical, bacteriological and radiological characteristics. The hydrogeochemical evaluation of groundwater quality in Auchi and its environs is conducted to ascertain its potability and facies types. Geologic mapping of the area revealed that the area is dominated by ferruginized sandstone. Thirty (30) groundwater samples were collected from the study area and sent to the laboratory analysis for chemical and microbial analyses. Prior to the laboratory analyses, physical parameters were determined insitu using a multi-meter. The It was observed that the hydrochemical parameters of the groundwater falls within the permissible limits of the NSDWQ of 2007 and WHO standard of 2004, with the exception of pH and iron concentration. The pH of the groundwater is 5.75±0.0707 indicating acidic water, and the iron concentration has a value of 0.375±0.1061 mg/l, which is beyond the permissible limits.The concentration sequence of the major cations of the groundwater in the study area is Ca2+ > Na+ >Mg2+ >K+, with Na+ value of 1.07±0.2121 mg/l, K+ 0.1950±0.0778 mg/l, Ca2+ 2.5750 ±1.2516 mg/l and Mg2+ 0.7750± 0.2756 mg/l. The concentration sequence of the major anions of the groundwater in the study area is Cl-> HCO3->NO3->SO4 2-, with Cl- value of 28.6500±4.4548 mg/l, HCO3- 21.4000±8.6267 mg/l, SO42- 0.3550±0.1485 mg/l and NO3-1.2500±0.9051 mg/l. The electrical conductivity (EC) of groundwater in the study area ranges from 49.10 to 580.40 µS/cm. It falls within permissible limits for NSDWQ and WHO. The total dissolved solids (TDS) in the groundwater of the study area have an average value of 42.95 mg/l, indicating fresh water. Stiff plots of the groundwater in the study area reveals that they are from the same aquiferous formation, and has a Calcium Bicarbonate (Ca-HCO3) hydrochemical facies.