University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 56 5 2025 07 23 Ecological and Environmental Risk Assessment of Cadmium Heavy Metal in Soil (Case Study: Shahr-e-Ray, Tehran Province) Ecological and Environmental Risk Assessment of Cadmium Heavy Metal in Soil (Case Study: Shahr-e-Ray, Tehran Province) 1401 1420 103194 10.22059/ijswr.2025.387772.669861 FA Shahla Rahmani Siyalarz Department of Soil Science, Faculty of Agriculture, College of Agriculture and Natural Resources, University of Tehran Ali Keshavarzi Department of Soil Science, Faculty of Agriculture, College of Agriculture and Natural Resources, University of Tehran Fereydoon Sarmadian Department of Soil Science, Faculty of Agriculture, College of Agriculture and Natural Resources, University of Tehran Journal Article 2024 12 28 Soil contamination with heavy metals, particularly cadmium (Cd), is one of the serious environmental challenges that has significant negative impacts on ecosystems and human health. This study evaluates the ecological and environmental risks of cadmium in a section of the agricultural lands in the Shahr-e Rey region of Tehran Province. In this regard, soil sampling was conducted from 41 points at a depth of 0 to 20 cm, and the total concentration of cadmium was measured using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) after digesting the samples with aqua regia, in accordance with the EPA 3050B standard. The results showed that the average cadmium concentration was 0.79 mg/kg, with a range of 0.17 to 2.05 mg/kg, which is below the permissible limits set by the Environmental Protection Agency of Iran. To assess contamination, environmental indices including the Geo-accumulation Index (Igeo), Contamination Factor (CF), Enrichment Factor (EF), and Ecological Risk Index (ER) were calculated. The Geo-accumulation Index ranged from -0.82 to 2.77, the Ecological Risk Index ranged from 25.50 to 307.50, the Enrichment Factor ranged from 0.69 to 8.57, and the Contamination Factor ranged from 0.85 to 10.25. These indices indicate moderate to relatively high pollution levels in most of the soil samples for cadmium in the studied region. The analysis of these four indices, along with field visits to the area, confirms that human activities have a significant impact on increasing the concentration of this heavy metal in the region's topsoil. This study emphasizes the necessity of proper irrigation and fertilization management to prevent the accumulation of heavy metals. Furthermore, the results clearly demonstrate the influence of industrial and agricultural activities on the increased concentration of cadmium in the region's soils, which could have serious consequences for human health and the environment. Based on the findings, urgent measures are essential to reduce contamination and protect soil resources. Soil contamination with heavy metals, particularly cadmium (Cd), is one of the serious environmental challenges that has significant negative impacts on ecosystems and human health. This study evaluates the ecological and environmental risks of cadmium in a section of the agricultural lands in the Shahr-e Rey region of Tehran Province. In this regard, soil sampling was conducted from 41 points at a depth of 0 to 20 cm, and the total concentration of cadmium was measured using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) after digesting the samples with aqua regia, in accordance with the EPA 3050B standard. The results showed that the average cadmium concentration was 0.79 mg/kg, with a range of 0.17 to 2.05 mg/kg, which is below the permissible limits set by the Environmental Protection Agency of Iran. To assess contamination, environmental indices including the Geo-accumulation Index (Igeo), Contamination Factor (CF), Enrichment Factor (EF), and Ecological Risk Index (ER) were calculated. The Geo-accumulation Index ranged from -0.82 to 2.77, the Ecological Risk Index ranged from 25.50 to 307.50, the Enrichment Factor ranged from 0.69 to 8.57, and the Contamination Factor ranged from 0.85 to 10.25. These indices indicate moderate to relatively high pollution levels in most of the soil samples for cadmium in the studied region. The analysis of these four indices, along with field visits to the area, confirms that human activities have a significant impact on increasing the concentration of this heavy metal in the region's topsoil. This study emphasizes the necessity of proper irrigation and fertilization management to prevent the accumulation of heavy metals. Furthermore, the results clearly demonstrate the influence of industrial and agricultural activities on the increased concentration of cadmium in the region's soils, which could have serious consequences for human health and the environment. Based on the findings, urgent measures are essential to reduce contamination and protect soil resources. https://ijswr.ut.ac.ir/article_103194_c4bb60a33b05d28f419b09328427b20a.pdf