Volume 7 Issue 4

ABSTRACT

Naturally radionuclides such as uranium, thorium, and radium continuously generate radon gas within the Earth's crust. Because radon is radioactive and chemically inert, its concentration in soil is widely used as an indicator of natural radioactivity and environmental contamination. The present study investigates radon concentrations in soil collected from selected locations in western Baghdad, Iraq, using CR-39 solid-state nuclear track detectors combined with the cylindrical diffusion chamber technique. Soil samples were collected from four locations at depths of 0, 10, 20, and 30 cm to evaluate the influence of depth on radon accumulation. Following a 30-day equilibrium period, the detectors were exposed for an additional 30 days before undergoing chemical etching in 7 N sodium hydroxide (NaOH) at 56 °C. The optimum etching time for the CR-39 detectors was determined to be 7 hours.

 The measured track densities were converted into radon concentrations in both the air volume of the diffusion chamber (Ca) and the soil samples (Cs). The results revealed a gradual increase in radon concentration with increasing soil depth at all sampling sites. The highest concentrations were observed at a depth of 30 cm, while the lowest values occurred at the soil surface. The maximum values were measured at the C-Half location, whereas the lowest concentrations were recorded at the center location on the surface. These findings indicate that deeper soil layers retain larger quantities of radon because gas diffusion toward the atmosphere is restricted by the overlying soil. Overall, the measured concentrations remained within the expected range for natural background radioactivity and provide valuable baseline information for future environmental radiation monitoring in western Baghdad.

Keywords: Radon, CR-39 detector, Solid-state nuclear track detector, Soil radioactivity, Environmental radiation, Radon concentration.