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 minin g on heavy metal contamination in the surface environment and its impl ications for soils and plants. Soils were sampled in and around a Pb-Z n mine in Korea from sites including the mine dump, nearby household g ardens and uncultivated areas. Various plants were also collected in t he 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 E mission Spectrometry (ICP-AES) included the metals Cd, Cu, Pb and Zn. Concentrations of heavy metals in soils decreased exponentially with d istance from the mine source mainly due to dispersion by water and top ography. The metal concentrations in the plant species sampled general ly decreased in the order: tobacco leaves > spring onions > soybean le aves > red pepper approximate to corn grain, although this order varie d for specific elements. These results agreed with other reports that metal levels in leaves (tobacco and soybean) are usually higher than t hose in fruit and grain (red pepper and corn). Tobacco leaves had elev ated concentrations of the heavy metals with maximum concentrations of 8.5 mu g g(-1) Cd (DW), 24 mu g g(-1) Pb (DW) and 1620 mu g g(-1) Zn (DW). The ratios of metal concentrations in plants to those in soils d ecreased in the order Zn > Cd > Cu > Pb. Factors influencing the bioav ailability of metals in soils and uptake into food crops were examined , including total metal concentration in soil, soil pH, cation exchang e capacity, organic matter content, soil texture and interaction among the elements determined. It is concluded that the total metal concent rations in soil and pH are the main factors influencing metal content in plants. (C) 1996 Elsevier Science Ltd