| Popis: |
Groundwater has been used for many purposes like domestic, agriculture, and industrialization in many regions of the world. Assessing groundwater quality and identifying pollutant risks are essential for managing groundwater resources. Ngoua watershed is located in sedimentary coastal zone of Douala. Groundwater is the major source of water for domestic purposes. Thus, the objective of this work is to assess groundwater chemistry and identify hydrochemical processes affecting groundwater quality of Ngoua catchment and its implication for domestic use. 30 groundwater samples were collected (23 wells, 4 springs and 3 boreholes) and physical-chemical parameters were analysed (T°, pH, TDS, EC), cations (Na+, K+, Ca2+; Mg2+ NH4+) and anions (Cl−, HCO3−, SO42− NO3−, PO43−, and F−) and calculation of groundwater quality index (WQI). The pH indicates that the groundwater in the study area is acidic to neutral. The temperature is similar to the ambient temperature of the study area (27 °C). The EC and TDS of the study area are average and the water are moderately mineralized. The order of mean abundance of the cation concentrations is as follows Ca2+˃Na+˃ Mg2+˃K+˃NH4+and the order of increasing classification of the anions is as follows NO3−˃Cl−˃SO42- ˃HCO3−˃PO43−˃F−The distribution of chemical facies of groundwater in the study area is as follows: 63.33 % Ca-HCO3, 23.33 % Ca-Mg-Cl and finally 13.33 % Na-Cl. The factors controlling groundwater chemistry are rock-water interaction, cation exchange, dissolution and anthropogenic activities may affect groundwater chemistry. Water Quality Index on this study varies between 2.12 and 187.21 with average of 29.67 and the majority of groundwater in the study area is acceptable in quality and can be used for domestic purposes such as drinking and irrigation. Nitrate and sulfate are the main contaminants of groundwater in the area. However, the high concentrations of NO3− in groundwater suggests than human activities (industrial and domestic activities) is intense and responsible factors for groundwater pollution in study area. Results of this study indicate importance of preventive measures to control groundwater contamination in Ngoua watershed. |
