Lead and Mercury Contamination Associated with Artisanal Gold Mining in Anka, Zamfara State, North Western Nigeria: The Continued Unabated Zamfara Lead Poisoning.

Abstract

A total of 24 soil samples were collected from areas around Artisanal Gold and associated Pb-Zn-Cu sulfide mining and mineral processing sites in the Anka mining district of Zamfara State, NW Nigeria. The samples were geochemically analyzed with the main objective of assessing the degree of Pb and Hg pollution in the environment resulting from the mining and mineral ore processing activities in the mining district and to consider the effect on human health. The assessment of the degree of pollution or toxicity was based on the Igeo (index of geoaccummulation) and EF (enrichment factor) where the former gives a quantitative pollution class with respect to the quality of the medium analyzed, while the latter differentiates between metals originating from anthropogenic activities and those from natural processes. The geochemical results show that the concentrations of Pb and Hg especially at the mineral processing sites significantly exceed the established thresholds (4,152 ppm and 12.92 ppm respectively). The calculated EF values for both Pb and Hg revealed that the soils from the entire mining district are extremely enriched in these elements, essentially originating from the anthropogenic activities (EF= >> 40). Lead and Mercury are toxic heavy metals with documented long-lasting adverse human health effects. These calls for efficient bioremediation measures for the removal of Pb and Hg from the contaminated soils that take into account the geochemical peculiarities of the mining district.