Determine the hazards of radioactive elements and radon gas manufacturing processes in an Egyptian fertilizer factory

Abstract

This study investigated the levels of radioactivity in soil surrounding a phosphate fertilizer factory in Egypt, aiming to assess potential risks to the population exposed to radiation. Concentrations of 238U, 226Ra, 232Th, and 40K were measured in soil samples collected from two subsites: one near the factory (subsite 1) and another further away (subsite 2). Two different systems were used for measuring radioactivity, a high-purity gamma ray spectroscopy system with an HPGe detector for gamma-emitting isotopes and a CR-39 solid nuclear track detector for alpha-emitting radon gas. Subsite 1, located close to the factory, displayed significantly elevated levels of 226Ra compared to global background levels (514 and 456 Bq/kg vs. 35 Bq/kg). Additionally, the concentrations of 238U (241.06 Bq/kg vs. global average 35 Bq/kg), 232Th (16.15 Bq/kg vs. global average 30 Bq/kg), and 40K (146.36 Bq/kg vs. global average 400 Bq/kg) were all above global averages. Furthermore, a high concentration of radon gas (337.06 μSv/y) was measured at subsite 1. The strong positive correlation observed between 226Ra and 238U (0.96256) provides further evidence of potentially elevated radioactivity levels near the factory. In contrast, subsite 2, situated farther from the factory, exhibited natural radioactive background levels within international limits. Quantitative analysis revealed that gamma ray absorbed doses for 226Ra and 232Th exceeded global averages in some samples. Specifically, 226Ra doses ranged from 7.8 to 46.26 ppm (exceeding the 20 ppm global average in some cases), and 232Th doses ranged from 1.98 to 9.14 ppm (exceeding the 10 ppm global average in some cases). The concentration of 40K, however, remained within the global range (0.07%–0.69 %). The observed imbalances in the ratios of Th/U (0.17–0.24 Bq/kg and 0.73–0.24 ppm) and U/Ra (0.81–0.73 Bq/kg and 0.73–0.17 ppm), both of which are significantly lower than their respective global averages of 4 and 2.4, point towards the presence of fertilizer-derived contamination. This conclusion is further supported by the high phosphate concentrations detected in the samples. Overall, this study suggests that radioactive contamination near the phosphate fertilizer factory significantly exceeds global background levels and international limits in some cases. This raises concerns about potential risks posed to surrounding agricultural land and crops.