HYDRO-GEOCHEMICAL AND QUALITY ASSESSMENT OF GROUNDWATER FROM SEDIMENTARY FORMATION IN THE MIDDLE BENUE TROUGH, NIGERIA

Abstract

Nasarawa State in Nigeria, is host to several mineral deposits. The groundwater resources in the State plays an important role in the socio-economic life of the people in terms of domestic, industrial and agricultural water supply. The effect of climate change, on the surface and groundwater resources, couple with the anthropogenic and geogenic activities on the quality of the various groundwater sources remained uncertain. Two hundred (200) water samples were collected randomly from boreholes and hand-dug wells from five locations (20 each) in Nasarawa South: Keana, Obi, Lafia and Awe Local Government Areas of the State, referred to as Middle Benue trough. 100 samples were collected during peak of dry season and another 100 during peak of rainy season. Cations, anions and heavy metals were analyzed using atomic absorption spectrometry (AAS); with aim of determining their concentrations in relation to suitability within the tolerance limit. The results revealed that heavy metals such as lead (Pb), manganese (Mn), Magnesium (Mg) and arsenic (As) have concentrations above World Health Organization (WHO 2017) and SON (2015) standards. The high concentrations are mostly associated with the Baryte and Lead-zinc mineralization present in Keana / Awgu formations in the Middle Benue Trough. Zinc (Zn), copper (Cu), cadmium (Cd), and iron (Fe2+) have their concentrations within World Health Organization (WHO 2017) drinking water permissible limits. The cations and anions present in the groundwater in the study areas had varying levels in terms of physico-chemical and bacteriological quality. In some areas bacteriological contamination rendered water sources unfit for human consumption, but suitable for agricultural purposes. Therefore, regular monitoring of the water sources in the affected areas are highly recommended.