Major Ion Chemistry and Quality Assessment of Groundwater in Maiduguri and Jere

Hydro-chemical conditions of groundwater in the upper aquifer system around Maiduguri and Jere local government area of Borno state were investigated. The geochemical processes controlling the concentrations and evolutions of the major ions in the aquifer indicates that water rock interaction is the major control. The concentrations of CA, Mg, SO4, and HCO3 are likely resulting from resolution of gypsum (CaSO4. 2H2), dolomite (CaMg(CO3)2), halite (NaCl) and magnesium sulphate (MgSO4) occurring in the aquifer matrix. However, other possible sources such as respiration or oxidation of organic matter and reduction of sulfate are attributed to higher concentration of HCO3 observed in some samples. The relatively higher concentration of Na, and Cl in the groundwater are most likely due to dissolution of halite (NaCl) which are probably occurring in the aquifer matrix. The plot of Na versus Cl was used to understand the overall Salinity in the groundwater, which is identified to be due primarily to the buildup of two major constituents (Na and Cl). Na excess relative to Cl in the samples is probably as a result of ion exchange of Ca or Mg for Na in the water and clay minerals which may probably be present in the aquifer materials. The relative high concentration of magnesium and calcium in the groundwater are most likely due to dissolution of dolomite (CaMg(CO3)2) which could be most likely source of these ions in the groundwater, since the mineral has ions as it's constituent. The relative concentration of calcium and sulphate in the groundwater are most likely due to dissolution of dolomite (CaMg(CO3)2) which could be most likely source of these ions in the groundwater, since the mineral has ions as it's constituent. The relative concentration of calcium and sulphate in the groundwater is most likely due to dissolution of gypsum (CaSO4.2H2) which could be most likely source of these ions in the groundwater. Various classifications of groundwater in the aquifer (Ca-Na-HCO3, Na-Ca-HCO3 and Na-HCO3 are important for regional hydrogeochemical studies. The assessment of water quality for domestic consumption shows that all the samples two or more of the ions above the WHO recommended limit. TDS values were used to understand the suitability of the groundwater for domestic consumption. The groundwater is considered good for consumption.