Heavy Metal Concentration Zoning in Soil of the Hiered Gold Exploration Area

The Hired mining area south of Birjand, South Khorasan province has been identified as the center of mineral pollution accumulation and it has been attempted to map the soils of the study area from their geochemical and environmental map. The maximum concentrations of Arsenic and Antimony were 5550 and 910 ppm, respectively. The enrichment factor (EF) for Arsenic, Antimony and Cadmium are 1.89, 2.05 and 0.03, respectively. This indicates the average contamination of the two elements Arsenic and Antimony and the lack of contamination of the area with Cadmium. According to the I-geo index, the degree of contamination of Arsenic and Antimony elements was 1, indicating a moderate contamination of the two elements in the region and less than 1 for Cadmium. Pollution Index (PI) for the Arsenic and Antimony elements in the area was moderate and for the Cadmium element, indicating that the soils of the study area were classified as non-polluted to moderately contaminated and most of this contamination is in the adjacent soils of the mine. In general, the soils of the study area have high levels of trace elements (above the natural background value) and if not controlled in the future, the pollution will reach a critical level and cause many problems for the inhabitants of the area.