Hydrochemistry of surface and groundwater along the Coast of Kribi and its environs

Abstract

Ground and surface water are the major sources of water supply to the population of Kribi and other communities around this area. A  hydrochemical investigation was carried out on the water sources in the area, aimed at identifying the various processes that control the  water chemistry, and to assess its quality for domestic purposes. Fifty-six water samples were collected from boreholes, springs, open wells, rivers, rain and tap within the study area during the months of October 2021 and March 2022. Physicochemical characteristics such  as pH, electrical conductivity (EC), total dissolved solid (TDS), temperature and major ions were analysed using standard methods. The  result indicated that, the pH ranged from 6.3 to 7.0 in the rainy season and 6.2 to 6.5 in the dry season indicating that water in this area is  slightly acidic to neutral. EC values ranged from 23.0 to 989µS/cm and 50.9 to 356µS/cm in the rainy and dry seasons respectively and the  high EC values in the rainy season indicates high mineralization of the water sources. The TDS ranged from 34.10 to 662.63ppm and 15.41  to 238.52ppm in the rainy and dry seasons respectively. The relative abundance of major ions was K⁺ > Na⁺ > Ca²⁺ > Mg²⁺> NH₄ ⁺ for  cations and NO₃ " > HCO₃ “ > Cl” > SO₄²" for anions. The main water types were: Ca+Mg-SO₄⁺Cl, Na+K-SO₄+ Cl, Na+K-HCO₃ and Ca⁺ Mg^-  HCO₃ for both seasons. The processes that influence the water chemistry were rock-weathering, mineral dissolution, ion exchange and  atmospheric precipitation. The chemical constituents were low and within the international recommended guidelines for drinking water  except for high concentrations of NO₃ ^- (284 mg/l) and K+ (75.8 mg/l). Water quality index calculated using data for chemical parameters  indicated that 96.8% of the water sources was of good to excellent for domestic purposes while 3.2% was of poor water quality. Based on  the above parameters, water sources in this area are suitable for domestic purposes.