Accumulation of Heavy Metals and Determination of Natural Radioactivity in the Soil-Thyme System in Omerli, Istanbul: Assessment of Ecological and Health Risk

Transfer of metals from soil to plant is an important pathway of human exposure to environmental contaminants. In this study accumulation of different metals was investigated and natural radioactivity levels were measured in the soil–thyme system. Results showed that the concentration of Br, Cr, Mn, Ni, and Pb in the soil is higher than the World average value, and P, Ca, and Zn have higher transfer factors. The natural radioactivity level in the soils is similar to the World average. For thyme samples the average values for 226Ra, 232Th and 40K were found as 22.7 Bqkg-1, 61.3 Bqkg-1 and 722 Bqkg-1, respectively. The health and ecological risks of soil were evaluated. The total hazard index of the child was 1.453 on average, greater than that of the adult (0.175), primarily due to the contribution of Cr. Ecological risk assessed based on various indices indicated that Pb and Ni show contamination risk to the environment. Our study confirms that metals in soil influence metals in plants, and those metal interactions are critical for pollution risk control.