Assessment of Some Heavy Metals in Paddy Soils and their Accumulation in the Organs of Rice in the Lenjan Area of Isfahan Province

In recent years, the accumulation of toxic heavy metals in grown rice at contaminated soil has led to a major concern. Accordingly, the quantities of heavy metals (Cd, Cu, Fe and Mn) were measured in soil, water and different parts of rice plants (Oryza sativa L.) cultivated (90, 6 and 41 samples, respectively) in Lenjan region. The studied area is located in Esfahan province and is exposed to various contaminants. The results showed that the concentrations of Cd in the water samples (0.005 mg/L) were less than the standard level (0.01 mg/L). However, its long term cumulative effects should be considered. The concentrations of Cu (23.4 mg/L), Fe (12708 mg/L) and Mn (108.9 mg/L) in roots of rice plant were higher than  their standard limits (20, 450 and 100 mg/kg, respectively). Also, the concentrations of Cd in the root, straw and grain (1.6, 1.1 and 1.3 mg/kg, respectively) of rice were higher than the standard limit (0.3 mg/kg), so it is more important for consumers, particularly local residents, to pay special attention to that. Transfer factors (TF) of Cu and Mn ions in different parts of rice plants showed that they were probably controlled by external factors such as atmospheric deposition in the region, because their mobilities were relatively low in the plants. The accumulation of Cu was the highest in the aerial part of rice plants in Chamgordan region which could be due to short distance of the region from the foundry smokestacks. Therefore, in addition to the effect of soil properties, human activities have a significant impact on the concentrations of the studied metals, which should be considered to achieve sustainable agriculture in the area.