Quality assessment of groundwater from shallow aquifers in Hong area, Adamawa state, northeastern Nigeria

Abstract

The present study evaluates the quality of groundwater in shallow aquifers in Hong area of Adamawa State, Northeastern Nigeria. Groundwater samples, soil samples and rock samples were collected during dry and wet seasons and subjected to laboratory analysis to determine their physico-chemical characteristics. The study revealed that the concentration of the major cations (calcium, magnesium, sodium and potassium) and anions (sulphate, chloride, bicarbonate, nitrate and phosphate) were below the respective permissible limit recommended by WHO and NSDWQ. The hydrochemical facies analysis indicates the groundwater in the area is Ca-HCO₃ type. The observed wide variation in the concentration of the electrical conductivity (10.00-1320.00  mg/L) and total dissolved solid (70.00-2690.00 mg/L) is an indication that the groundwater in the area contained dissolved ions. The slightly acidic water (5.50-6.94) in the area encourages the dissolution of iron and fluoride mineral into the groundwater system. High iron content (0.03-0.93 mg/L) in water as against the recommended value of (0.30 mg/L) does not pose any health threat but deteriorates the colour, odour and taste of water while the high fluoride concentration (0.06-2.58 mg/L) in the groundwater system as against the permissible limit of (1.50 mg/L) has resulted in dental fluorosis in the area especially in children between the ages of 10 to 20 years. The high fluoride in the groundwater in Hong area is clearly geogenic and due to chemical weathering and subsequent decomposition, dissociation and dissolution of fluoride bearing minerals (nacaphite) within the porphyritic granite portion. The high content of fluoride and iron in the groundwater may have contributed to the high EC and TDS especially during the rainy season when the rate of leaching and infiltration is high.

Keywords: Quality Assessment, Groundwater, Shallow Aquifer, Hong, Northeastern Nigeria