Heavy Metal Contamination in Topsoil in Mining-Plagued Communities in the Amansie West District, Ghana

Abstract

ABSTRACT This study was conducted in five randomly selected small-scale mining communities in the Amansie West District of Ashanti Region, Ghana to assess the impacts of small-scale mining activities on heavy metal presence in three different land use types (mined site, farmland and forest area). Using a random sampling design, a total of 60 soil samples were collected from 0–20 cm depth and analyzed for soil heavy metals: arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg) and copper (Cu) using Two-way ANOVA. Heavy metal concentrations for As (5.571 mg/kg), Cd (0.002 mg/kg), Cu (1.158 mg/kg), Pb (0.076 mg/kg) in the communities did not exceed the FAO/WHO permissible limits with the exception of Hg concentrations for the respective communities (0.68 mg/kg, 1.07 mg/kg, 1.26 mg/kg, 1.28 mg/kg, 17.03 mg/kg) whose levels were 2.3 to 56.8 times higher than FAO/WHO permissible limits (0.3 mg/kg). The distribution of heavy metals in the soil was not uniform across the different land use types in the mining landscape. Differences in heavy metal concentrations were significant (p < .05) at the community, land use and their interaction (community*land use) levels with the exception of As concentration at the land use level (p > .05). The study concludes that soils of the major land use types in the study area (mined sites, farmlands and forest area) are all contaminated by Hg accumulation. Therefore, effective rehabilitation of mined sites in mining-plagued-communities should include measures for removing mercury from the soil.