Assessment of trace elements contamination of agricultural topsoil around lakhouat mine area, Tunisia

Soil contamination by Pb, Zn and Cd was characterized in the surrounding area of the abandoned Lakhouat mine. The mine area was divided into 3 zones. Eighteen topsoil samples were sampled from each zone and were characterized, determining the total trace element concentration by acid digestion of Pb, Zn and Cd. Samples belonging to the mine tailing dam showed the highest values of contamination, with mean concentrations of 2925 mg kg-1 for Pb, 7297 mg kg-1 for Zn, and 37 mg kg-1 for Cd. High concentrations of Pb, Zn and Cd were found in many samples taken from the surrounding soils and agricultural soils, indicating the extent of spreading pollution of trace elements. Contaminations in soils were classified as enrichment factor, contamination factor and contamination degree. Factor values indicate that trace elements contamination levels of soils on the 3 studied zones are classified as high contamination factors. A principal component analysis revealed the presence of one common source in the mining area. Cluster analysis showed a close association between soils with similar trace elements concentration. Spreading of tailing wastes from dams of the mining facilitating via rain or wind is the main source of soil contamination of agricultural soils.