Environmental Impact of Artisanal Gold Mining around Kataeregi Area, North-central Nigeria

Abstract

The geology and geochemical studies of water, stream sediments and rocks from Kataeregi artisanal gold mining, North-central Nigeria was carried out with the aim of determining its host rocks, assessing the impact of such activity on the surrounding and evaluating the suitability of the water in the area for probable uses. The field work involves the collection of representative rock, water, and sediment samples along stream, mined and background areas within the location of study. The rock and sediment samples were analyzed for trace element concentrations using X-ray fluorescence spectrometry. Water samples were analyzed for cation, anion and trace elements determinations. The average concentration of these trace elements in rocks and sediments were compared with published average crustal abundances of the elements in upper continental crust and the water compared with Nigerian Standard for Drinking Water Quality (NSDWQ, 2007) and World Health Organization (WHO, 2011) Standards. Geological field mapping show that 60% of the total area is underlain by Migmatite Granite-Gneiss complex while Schist account for 20%. The geochemical analysis of the representative rock samples indicates probable Au-Ag-Hg mineralization with average concentrations of 0.16ppm, 2.53ppm, 0.21ppm respectively. Au is hosted by the Schist rocks found within the central portion of the study area while Ag and Hg occur in both Migmatite Granite-Gneiss complex and the Schist rocks. Geochemistry of the sediment samples revealed the sediments are enriched with elements such as Au (0.23ppm), Ag (2.59ppm), Hg (0.21ppm) and Mo (1.14ppm). Findings from the water analyses and Langguth trilinear diagram revealed the water to be earth-alkaline fresh water with high alkaline content, and mostly sulphate type. The elevated Pb content in water is attributed to the influence from local geology and gold mining activities while the Fe and SO4 could results in input from oxidative weathering of pyrite associated with the gold mineralization in the area. These trace metals like Hg in rocks and sediments, and Pb in water from the study area can get consumed directly or indirectly through food chain. They are potential toxic elements that can render water unfit, causes slow growth rate in plant and respiratory, nervous and reproductive disorder in man. Regulations should be put in place to curtail excessive ground opening during mining, environmentally friendly and scientific usage of mercury in gold processing encouraged, and indiscriminate mined waste disposal discouraged. However, it is advisable to explore and exploit for Ag to compliment Au exploitation in the area.