Assessment of Surface and Groundwater Quality in Gussoro Gold Mining Site, North Central Nigeria

Abstract

The water quality in Gussoro area of Niger state, North central Nigeria was investigated in this study. Gussorro is located at the downstream of River Shiroro where the community carries out farming, artisinal mining and fishing activities. Field geological mapping of the area revealed that schist is the major lithological unit in the area. This schist was intruded by medium grained granite on the north eastern part of the study area. The results of the laboratory analysis of both surface and groundwater samples indicate the pH of water in some locations is slightly acidic. The concentration of all analyzed cations (sodium, magnesium, calcium and potassium) as well as major anions (sulphate, chloride, bicarbonate, carbonate and nitrate are all belloe W.H.O. maximum permissible limits. However, in some locations, the concentration of flouride, iron, nickel,manganese and arsenic were high that the maximum permissible limits. There enrischment in the water could be attributed to mining and farming activities in the area. The slightly acidic nature of the water enhances chemical weathering and rock dissolution process in the area, thereby enriching the water with this element. Presently, there are no cases of dental flourosis in the study area despite high concentration of fluoride in some locations. High concentration of fluoride in the water can be attributed to weathering of flouride bearing mineral such as apatite and fourite in granitic rock located in the north eastern part of the study area. Nickel, manganese, lead, and arsenic are pathfinders element to gold and are often discarded as gangue into the surrounding soil and surface water. This partly explains the concentration of these metals are higher in surface water compare to groundwater. High concentration of iron in the water is due to the oxidation and weathering of pyrites that is associated with gold mineralization in the area. Water types in the area from Durov and piper diagram revealed Na+ Ca/ClSO4 facies. Gibbs diagram also indicated that weathering is the major hydrogeochemical process controlling the discharge of ions in water sources in the area. Water in areas with anomalous concentration of flouride and heavy metals should be treated before used.