Investigation of radon emission rates and effective radium contents in soils of ni̇lüfer, yildirim and gürsu districts of bursa

All living organisms on Earth are incessantly exposed to radiation originating from both natural and anthropogenic sources. Among these, natural radiation constitutes the primary contributor to the background radiation to which all humans are exposed. This type of radiation emerges predominantly from the Earth's crust, where radioactive elements are ubiquitously distributed within rocks, soil, and water. Furthermore, building materials derived from natural resources inherently contain trace amounts of radioactive substances, further contributing to the ambient radiation levels within human habitats. As a consequence, individuals are continually subjected to radiation in their immediate surroundings, including within their homes and workplaces. Even the air we breathe and the water we consume carry radionuclides transferred from the soil, rendering radiation exposure an unavoidable aspect of daily life. This study focuses on investigating the radon diffusion rates and the effective radium content of soil samples collected from three distinct districts in Bursa, Turkey: Nilüfer, Yıldırım, and Gürsu. The "sealed can technique," combined with LR-115 solid-state nuclear track detectors, was employed to achieve this objective. The methodological approach began with the excavation of soil samples from depths of 15–20 cm, with each sample weighing approximately 1.5–2 kg. The samples were carefully labeled and transported to the research facility, where they underwent a meticulous preparation process. Stones, plant residues, and other extraneous materials were manually removed, followed by a drying process involving exposure to high temperatures to eliminate residual moisture content. This ensured that the subsequent measurements would not be influenced by environmental humidity. Once dried, the soil samples were sieved using a 2-mm mesh to achieve homogeneity and subsequently apportioned into sealed containers, each holding precisely 125 grams of soil. LR-115 films, integral to recording the radon tracks, were affixed to the inner surfaces of these containers. To ensure the accuracy of the measurements, the containers were hermetically sealed to prevent any air exchange and were left undisturbed for a duration of 90 days, allowing sufficient time for the accumulation of radon gas within the confined space. At the conclusion of the exposure period, the containers were opened, and the LR-115 films were retrieved for chemical processing. A 10% solution of 2.5N sodium hydroxide (NaOH) was utilized to etch the films chemically. This process was conducted at a controlled temperature of 60°C over a period of two hours, rendering the latent tracks left by alpha particles visible under microscopic examination. The etched films were subsequently rinsed in pure water to remove any residual chemicals, ensuring clarity for analysis. Using the Image-J software under 100X magnification, the radon tracks were meticulously counted, and the obtained data were subjected to rigorous mathematical calculations to convert the raw measurements into internationally standardized units.The results revealed that radon concentrations within the study area ranged from 15,70 to 813.78 Bq/m³. Furthermore, the exhalation rates, both mass-based and surface-based, exhibited significant variability across the sampled districts. Specifically, in Nilüfer, the mass exhalation rates were determined to range between 554,05 and 1490,04 mBqkg-1 h-1, while surface exhalation rates ranged from 13,77 to 70,27 Bqm-2h-1 In Yıldırım, the mass exhalation values ranged from 157,94 to 8186,65 mBqkg-1 h-1 with surface exhalation values spanning 3,92 to 203,45 Bqm-2h-1. In Gürsu, the mass exhalation rates varied between 360,38 and 1125,65 mBqkg-1 h-1, while surface exhalation rates ranged from 8,96 to 26,46 Bqm-2h-1. One noteworthy finding was an anomalously high radon concentration at a specific location in Nilüfer. Upon closer examination, it was determined that this particular sampling site was characterized by a rocky geological substrate, which likely contributed to the elevated radon levels. Despite this anomaly, when the results were compared with radiological safety thresholds established by national and international organizations such as TENMAK, WHO, and IAEA, the majority of the samples were found to fall well within acceptable limits. This indicates that the overall radiological risk posed by radon in the studied regions is minimal and does not present a significant health concern for the local population. It is extremely important to understand the potential effects of radon gas on human health and to consider the risks, especially in areas with high concentrations. Radon is a naturally occurring radioactive gas. It results from the decay of radioactive elements such as uranium and thorium and is particularly associated with natural environments such as rocks, soil and groundwater. In the normal respiratory process, radon gas enters the lungs with the air and is expelled again. Under typical conditions, there are no harmful effects because the human body is able to excrete the gas efficiently. However, the situation is different in areas with high radon concentrations. In such environments, the decay products of radon emit radioactive alpha particles. Alpha radiation is capable of causing high-energy damage to biological tissues. When radon gas is inhaled into the lungs, these particles can settle in the lung tissue and accumulate there, causing DNA damage at the cellular level. The accumulation of DNA damage over time can lead to abnormal cell proliferation and an increased risk of lung cancer. This is particularly pronounced for people living in areas with prolonged exposure to high levels of radon. Epidemiological studies have clearly demonstrated the association between radon exposure and the development of lung cancer. The World Health Organisation (WHO) and other international health organisations state that radon is the second most important cause of lung cancer after smoking. Poor ventilation conditions, especially indoors, can increase the accumulation of radon gas. Radon concentrations are generally higher in ground floors, basements and underground structures, and individuals living in such areas are considered to be at greater risk. Effective monitoring and prevention strategies should be developed to reduce health risks from radon. Measures that can be taken include regular concentration measurements with radon measuring devices, improving ventilation systems in case of high levels, or designing buildings to prevent radon migration. These efforts play a critical role in the prevention of radon-related health problems and improve the quality of life of individuals In this study, the sampling strategy was designed to capture diverse environmental conditions. For instance, in Nilüfer, samples were collected from both industrial andnon-industrial zones to assess the potential influence of industrial activity on radon levels. In Gürsu, the focus was on comparing processed and unprocessed agricultural soils, while in Yıldırım, samples were collected without specific selection criteria to provide a more generalized overview of the district. In conclusion, the findings of this research emphasize the necessity of ongoing surveillance of natural radiation levels, particularly in regions with varying geological and environmental characteristics. While the measured radon concentrations in this study are largely within safe limits, the presence of isolated high-radon zones highlights the need for localized interventions to mitigate potential health risks. Such proactive measures are essential for safeguarding public health and ensuring long-term environmental safety.