Assessment of Shallow Groundwater Quality Using Water Quality Index and Human Risk Assessment in the Vogan-Attitogon Plateau, Southeastern (Togo)

The shallow Continental Terminal aquifer constitutes the primary water resource for drinking purpose in the coastal sedimentary basin of Togo, facing population growth, mining development, industrialization, and intensive agriculture. This study aims to assess groundwater quality and associated human health risks, to ensure the sustainable water supply in the basin. Major chemical parameters, and trace elements of forty-two samples of shallow groundwater and eight samples of surface water collected during march 2019 were analysed using AFNOR methods. The dataset obtained was used to evaluate drinking water quality and safety. The results showed that groundwater was slightly acid (4.83 + > Ca2+ > Mg2+ > K+ and Cl- > SO42- > HCO3-> NO3-. Thus, water samples were predominantly Na - Cl water type (~88 %). The water quality index score based on major ions indicated that 93% of the groundwater samples were classified as excellent and good for drinking. The non-carcinogenic risk ranged from 3.887 to 17.650 for children, from 2.272 to 10.135 for adult females, and from 1.785 to 8.104 for adult males and was related principally to manganese, nitrate, arsenic, fluoride and cadmium. The carcinogenic risk ranged from 0.004 to 0.006 for children, 0.003 to 0.004 for adult females, and from 0.002 to 0.003 for adult males and was caused by arsenic and cadmium. The water quality is affected by seawater intrusion, evaporite dissolution and anthropogenic contamination. The consumption of groundwater may cause health effect on human.