Heavy metal pollution status and risk assessment on area with artisanal mining activities

摘要

This study was undertaken to re-evaluate the heavy contamination level of Bagega community which recorded acute lead poisoning in 2010 and was reclaimed between 2010 and 2012. The levels of the following heavy metals (Zn, Pb, Hg, As and Cd) was measured in sixteen sampling sites around Bagega and its environs using Varian AA240 Atomic Absorption Spectrophotometer. The assessment of pollution was achieved using the Effect Range Low (ERL) and Effect Range Median (ERM), pollution index (PI) and geoaccumulation index (Igeo). The result revealed that the soil samples within Bagega community recorded concentration below the geochemical background for analyzed heavy metals. Soils around abandoned gold mine fields show high concentration of Pb, Cd, Hg and As. Based on the ERL and ERM values, Bagega and Topeki communities recorded low to high contamination of heavy metals, while abandoned mine fields and within farmland recorded moderate to very high contamination. Pollution index analysis show insignificant contamination within Bagega and Topeki communities while farmland and abandoned mining axis recorded significant contamination of Pb, Hg and As. The Igeo indicates that relatively higher levels of Pb, Cd and Hg was recorded; suggesting heavy metalcontamination. Generally, soils around Bagega community were found to range from uncontaminated to moderately contaminated. Though land reclamation within Bagega community may have reduced heavy metal levels, the study reveals high risk of heavy metals toxicity to inhabitants due to farming of arable land around mining areas.Keywords: Lead poisoning, risk, toxicology, effect range low, effect range median, pollution index, geoaccumulation.