Assessment of heavy metal levels in surface water, sediment and agricultural soils around the abandoned Laga Dambi gold mine, Ethiopia.

Environmental contaminants from mining activities are becoming problematic in the developing world, necessitating greater attention to their fate and transportation. In particular, gold mining activities that utilize strong lixiviants may result in heavy metal dissolution and distribution to environmental compartments. This study aimed to determine the status of some selected heavy metals in stream water, sediment and agricultural soil near a large-scale cyanidation gold mining operation, Laga Dambi. Ethiopia. The stream water, sediment and soil samples were digested under optimal digestion conditions. Inductively coupled plasma-optical emission spectrometer was used to determine the concentrations of Zn, Mn, Cu, Fe, Sn, Co, Ni, Cr, Pb, Cd, As, and Hg in samples collected from potentially contaminated sites associated with the Laga Dambi gold mine and control sites. The mine is notable because it is disposed of tailings in an impoundment created in a stream zone, where the stream flows over the tailings facility before exiting the mine site. The mean concentrations of the heavy metals in stream water and sediment were generally higher than the recommended levels reported by international agencies. The mean concentrations of Sn, Cr, Cd, and Hg were also high in agricultural soil that received irrigation water from the mine down gradient rivers. In general, stream water, sediment and agricultural soils were found to contain high concentrations of heavy metals, particularly Hg and As, which are typically associated with gold mining. The findings show that the heavy metal concentrations of stream water, stream bank sediment, and agricultural soil were high, indicating an increased risk for community exposure during consumption under the current conditions. On the basis of these findings, we strongly recommend strict monitoring and regulatory control of the study area to protect the environment and health of exposed populations.