Heavy metal contamination of soils and plants in the vicinity of a lead-zinc mine, Korea

Current research has been focused on the influence of base metal mining on heavy metal contamination in the surface environment and its implications for soils and plants. Soils were sampled in and around a Pbsingle bondZn mine in Korea from sites including the mine dump, nearby household gardens and uncultivated areas. Various plants were also collected in the household gardens including corn grain, red peppers, soybean leaves, spring onions and tobacco leaves. Similar materials were taken from a nearby control area. Analysis by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) included the metals Cd, Cu, Pb and Zn. Concentrations of heavy metals in soils decreased exponentially with distance from the mine source mainly due to dispersion by water and topography. The metal concentrations in the plant species sampled generally decreased in the order: tobacco leaves > spring onions > soybean leaves > red pepper ≈ corn grain, although this order varied for specific elements. These results agreed with other reports that metal levels in leaves (tobacco and soybean) are usually higher than those in fruit and grain (red pepper and corn). Tobacco leaves had elevated concentrations of the heavy metals with maximum concentrations of 8.5 μg g−1 Cd (DW), 24 μg g−1 Pb (DW) and 1620 μg g−1 Zn (DW). The ratios of metal concentrations in plants to those in soils decreased in the order Zn > Cd > Cu > Pb. Factors influencing the bioavailability of metals in soils and uptake into food crops were examined, including total metal concentration in soil, soil pH, cation exchange capacity, organic matter content, soil texture and interaction among the elements determined. It is concluded that the total metal concentrations in soil and pH are the main factors influencing metal content in plants.