Evaluation of selected heavy metals on the artisanal gold mining sites in North Rift Region, Kenya

Abstract

ASGM activity significantly contributes to the economies of developing countries with a consequent impact on the socio-ecological systems. The impacts are largely due to the wide use of mercury in the extraction processes. It also deforestates the exploited areas with consequent loss of biodiversity and ecosystem functions. ASGM has varied impacts of adverse health effects and it is said that mercury has more significant health effects than other heavy metals (Cd, Pb, As, and Cr). Due to dearth in the studies on artisanal mining in Kenya, the study sought to evaluate the concentration levels of selected heavy metals on the artisanal mining sites in Nandi and West Pokot Counties of Kenya in order to determine their nature, concentration levels and suggest mitigation measure. The study was done in two artisanal gold mining sites in Kapsaos in Nandi County and Sekker in West Pokot County in Kenya and employed a comparative analysis to examine the attributes of these locational spaces. Thirteen samples were randomly collected from tailings at different points from the tailing disposal site in Kapsaos areas and Sekker site. The samples were transported prepared and stored at Environmental Chemistry Laboratory, the University of Eldoret where it was subjected to Atomic Absorption Spectroscopy (AAS). The laboratory analysis results showed that the samples from both artisanal gold mining sites contained several heavy metals which included Chromium, Cadmium, and Lead. Overall, the mining sites in Nandi County had the following concentration of Cr, 0.4195 ppm, Cd, 0.2470 ppm, and Pb, 0.6300 ppm, while the mining sites in West Pokot county had the following concentrations:  Cr, 0.1790 ppm; Cd, 0.0050 ppm; and Pb, 0.7400 ppm. Besides, the concentrations levels of Lead and Cadmium were above the WHO guidelines. A casual look at the concentration levels indicates that the mining sites in Nandi County have higher concentration levels of selected heavy metals (Pb, Cd and Cr) that in West Pokot County which was attributable to the ASGM activities. The study concluded that ASGM activities excavates, destabilizes the stables states of elements and then concentrates them. Finally, the study recommends that ASGM be upscaled instead of being frowned upon. Further studies on the potential socio-economic impacts on the ASGM activities in Western Kenya because the activity is considered a complementary/supplementary economic activity.

Keywords: Artisanal and small scale gold mining (ASGM), artisanal mining, selected heavy metals, mercury, heavy metal pollution

DOI: 10.7176/JEES/10-6-12

Publication date:June 30^th 2020