Assessment of Heavy Metal Pollution of Soil-water-vegetative Ecosystems Associated with Artisanal Gold Mining

Worldwide demand for gold has accelerated unregulated, small-scale artisanal gold mining (AGM) activities, which are responsible for widespread environmental pollution in Ghana. This study was conducted to assess the impact of AGM activities, namely the heavy metals pollution of soil-water-vegetative ecosystems in southern Ghana. Composite soil, stream sediments and water, well water, and plant samples were randomly collected in replicates from adjoining AGM areas, analyzed for soluble and total Fe, Cu, Zn, Pb, Cd, Hg contents and other properties, and calculated for indices to evaluate the extent of environmental pollution and degradation. Results indicated that both well and stream waters were contaminated with heavy metals and were unsuitable for drinking due to high levels of Pb (0.36-0.03 mg/L), Cd (0.01-0.02 mg/L), and Hg (<0.01 mg/L). Enrichment factor and geo-accumulation index showed that the soil and sediments were polluted with Cd and Hg. The soil, which could have acted as a source of the Hg pollutant for natural vegetation and food crops grown near AGM areas, was loaded with 2.3 times more Hg than the sediments. The concentration of heavy metals in fern was significantly higher than in corn, which exceeded the maximum permissible limits of WHO/FAO guidelines. Biocontamination factor suggested that the contamination of plants with Hg was high compared to other heavy metals. Further studies are needed for extensive sampling and monitoring of soil-water-vegetative ecosystems to remediate and control heavy metals pollution in response to AGM activities in Ghana.