Document Type : Research Paper




Mining and its various stages is one of the important factors in spreading pollution in natural environments. Contaminations may affect soil and water resources and actually enter the food chain due to absorption by plants. Among mineral elements, lead is more important because of its toxic effects. In order to investigate distribution of lead in downstream soils of Kushk Lead and Zinc Mine and identify anthropogenic and geogenic natures of pollution spread, a classified random systematic sampling was carried out. Sampling interval was 500 to1500 meters and soils were sampled in 0-5 and 5-30 centimeters depths. A control sample area with similar characteristics was considered in the vicinity of the region. The samples were analyzed by ICP-MASS method and the lead content of the samples was determined. Using Enrichment Factor and Geoaccumulation Index, the extension and severity of pollution are determined and related maps are prepared. Conclusions show that average amounts of lead in topsoil is about 4 times of subsoil and one kilometer far from mine, lead content of soil is more than 290 PPM that is more than permissible amounts. Moreover, the difference between lead content in topsoil and subsoil shows that the contamination in these areas is anthropogenic. Contamination reduces by going further from mine and the highest amount of emission of lead is around the main watercourse.