Mercury Contamination Risk Assessment in Artisanal Small-Scale Gold Mining Sites in Uke and Environs, Nasarawa State
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Date
2023-12
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Lead City University
Abstract
The main focus of this research was to investigate the environmental effects of the use of mercury, a potent neurotoxicant, by artisanal miners processing gold at Uke mining sites in Nassarawa State. The research adopted multidisciplinary research approach involving analytical, quantitative and geospatial methods. The samples analyzed for both seasons includes, 10 fish samples,39 water samples, 24 plants samples, 20 soil (wastes) tailing samples,20 agricultural soil samples and 3 river sediments. The mercury concentration was measured using Direct Mercury Analyser (DMA80) and USEPA 7473 standard method. Moreover, remote sensing technique was adopted to process satellite imageries to extract NDVI values and Land use cover for the
area. Results showed concentrations of mercury in fish within WHO allowable human consumption limit of 0.5 mg/kg, with bioaccumulation order within the organs as follows; gills>liver>intestine >muscle>bone. The values in soil ranges from 0.0162 to 0.387 mg/kg in wet season while the dry season ranges from 0.025 to 4.125 mg/kg which is above the crustal average of 0.003 mg/kg. The tailings have 0.003 to 0.142 mg/kg in dry season while 0.011 to 0.314mg/kg in the wet season which is above expected limit. Plants mercury concentration confirmed that Rice, Pepper and Sweet Potato are above the allowable range of 0.03-0.1mg/kg and should be a concern for food safety in the area. The mercury in river Uke is above WHO threshold of 0.002 mg/kg. The result indicates positive correlation with low NDVI values and stressed vegetation. The Geoaccumulation Index and Contamination Factor Values, confirmed low contamination with the soil tailings as a point sou. This work developed a GIS-based model using the weighted method in ARCGIS to help predict mercury migration and produce pollution vulnerability map for risk management.
Keywords: Gold, Mercury, Remote Sensing, Tailings, Fish
Word count: 299
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Keywords
Gold, Mercury, Remote Sensing, Tailings, Fish