Assessing groundwater suitability and nitrate health risk in Edea, Cameroon: implications for drinking and irrigation purposes

Groundwater is the main source of freshwater for drinking and irrigation in Edea. However, growing demands from agriculture, population growth and urbanization have adversely affected groundwater quality in the area. Hence, the objectives of this study were to evaluate the suitability of groundwater for drinking and irrigation uses and quantify the human health risks associated with consuming nitrate-contaminated water in the study area. Groundwater samples were collected and analyzed to evaluate water quality based on thirteen hydrochemical parameters: pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), bicarbonate (HCO3-), chloride (Cl-), nitrate (NO3-), sulfate (SO42-), and phosphate (PO43-). The study revealed that anion abundances followed the order of HCO3- > NO3- > Cl- > SO42- > PO43- while cation abundances were Ca2+ > Mg2+ > Na+ > K+. According to WHO standards, the pH, HCO3-, PO43- and NO3- levels exceeded their prescribed limits. The main source of nitrate was identified as fertilizer usage in agricultural fields. The groundwater was predominantly characterized as Ca-Mg-HCO3 and Ca-Mg-Cl-SO4 types, which resulted primarily from water-rock interactions. Water Quality Index (WQI) analysis found that the groundwater was generally good for drinking. Regarding irrigation suitability, the groundwater in the region generally met the criteria for %Na, SAR, RSC, KI, PS and PI, making it suitable for irrigation. However, 43.48% of the samples were deemed unsuitable based on the magnesium hazard. Furthermore, the study observed that the corrosivity ratios in 39.13% of samples were high enough to potentially cause corrosion when transporting water through metal pipes. The health risk assessment revealed that children in the study area faced a higher risk compared to teenagers and adults. The study proposed management measures to protect groundwater resources in the area.