The impact of gold ore mining on total lead (Pb) concentration in some mining and residential communities in Zamfara State, Nigeria

Abstract

Illegitimate artisanal gold mining quite often results in elevated lead (Pb) concentrations in mining and residential areas close to ore mining sites, which exposes the communities to varying degrees of health and environmental challenges.Here,mining and residential soils from Abare, Dareta and Bagega, Anka local government,Zamfara state's exposed communities, were examined for total Pb concentration.Three replicates of soil from four different soil fields in mining and residential areas were carefully selected for sampling from the surface layer 0 to 21 cm.All thesoil samples were digested and analysed using flame atomic absorption spectrophotometry (Varian model-AA240FS). The total Pb concentration in the mining areas ranges from 466.01-729.13 mg/kg (Abare), 151.34-168.21 mg/kg (Bagega) and 108.89-258.88 mg/kg (Dareta), while those from the residential areas ranges from 326.28-391.38mg/kg (Abare), 67.74-79.44 mg/kg (Bagega) and 17.58-43.40mg/kg (Dareta).This study revealed that the Pb concentration in all mining areas exceeded the standard ofthe department of petroleum resources of Nigeria's 85 mg/kg threshold (DPR).According to the study, the only residential communities with Pb concentrations above the DPR threshold are those in Abare.Based on the computed degree of contamination indices in those areas using the single pollution index (SPI) and Nemerow composite pollution index (NCPI), the study revealed the residential sites are within the safety limit, whereas the mining sites are slightly contaminated. Nevertheless, more studies are needed to determine the Pb speciation in those areas.