Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2026Long-term decline of Chernobyl-derived 137Cs in mosses and lichens from the Eastern Black Sea region of Türkiye
Çevik, Ugur; Çelik, Necati; Uzun, Kubra K.; Çelik, Ahmet; Koz, Bahadir; Özen, Songul A.; Yesilkanat, Cafer M.; Hacisalihoglu, Aylin; Özkalayci, Fatih; Kaya, Selim
This study presents the third consecutive assessment of 13 Cs activity concentrations in the same 50 moss (7 species) and lichen (2 species) sampling points in Ordu province, T & uuml;rkiye, one of the most heavily contaminated areas following the Chernobyl accident. Samples were collected from exactly the same locations used in the 1997 and 2007 studies and analyzed by high-resolution gamma spectrometry. In 2025, detectable 13 Cs was found in 14 of 30 moss sites (47%) and 3 of 20 lichen sites (15%). For samples below the minimum detectable activity (MDA), a value of MDA/2 (0.93 Bq kg-1) was substituted for lichens, while moss samples below the MDA were excluded from regression. The ecological half-life (Teco) for the 2007-2025 period was 4.38 +/- 1.05 years for mosses and 4.18 +/- 0.61 years for lichens. For mosses, this is nearly identical to the 1997-2007 mean (4.4 years), while for lichens it decreased from 5.6 to 4.18 years, suggesting a slight acceleration in environmental removal. All Teco values remain far shorter than the physical half-life of 13 Cs (30 years), confirming that environmental removal processes dominate over radioactive decay. Residual 13 Cs is concentrated in higher-altitude areas, reflecting the original deposition pattern and slower removal in cooler, more humid microenvironments. Nearly 39 years after the accident, the radiological risk posed by residual trace levels is negligible. This 28-year dataset provides one of the longest continuous records of 13 Cs in epiphytic bioindicators and serves as a valuable baseline for future contamination events.
- MakaleYalnız künye2013Assessment of Radiological Levels at Schools in Trabzon, Turkey
Çevik, Ugur; Çelik, Ahmet; Çelik, Necati; Özkalayci, Fatih; Akbulut, Songul
In this study, a survey on environmental radioactivity in 16 high schools located in north eastern region of Turkey (the black sea region, province of Trabzon) was carried out. Indoor air radon (Rn-222) concentrations were measured in spring and autumn 2008 seasons using LR115 solid state nuclear track detectors and gamma radioactivity levels were measured using an HPGe gamma ray detector. It was seen that mean radon activity concentrations in schools ranged from 31 to 157 Bq/m(3) for spring season and from 38 to 114 Bq/m(3) for autumn season. The mean gamma activity concentrations in located areas of schools are between 18-52, 21-59, 11-97 and 265-759 Bq/kg for Ra-226, Th-232, Cs-137 and K-40, respectively. The annual effective doses of students and staff received due to radon and locations' gamma radioactivity levels are calculated.
- MakaleYalnız künye2012Effect of detector collimation on the measured mass attenuation coefficients of some elements for 59.5-661.6 keV gamma-rays
Çelik, Necati; Çevik, Ugur; Çelik, Ahmet
Mass attenuation coefficients were determined experimentally for Sc, Ni and W for gamma energies of 59.5, 122, 276, 302, 356, 383 and 662 keV for different detector collimator diameters ranging from 2 to 10 mm. The aim was to investigate the quantitative analysis of detector collimator diameter effect on measured mass attenuation coefficients. It was found that measured mass attenuation coefficients decrease systematically with the increasing collimator diameter. The relative difference was found to be up to around 3% in some cases. The observed decrease in mass attenuation coefficients was attributed to the detection of elastic and inelastic scattered photons from the absorber. In elastic scattering process the photons change in direction but not in energy and get counted under the full energy peak if they reach the detector. In inelastic scattering however, both direction and energy of the scattered photons change. It was seen that most of the inelastic scattered photons also get counted by the detection system since they lose an amount of energy lower than the energy resolution of the detector. It is understood from the present results that it is essential to take into account the experimental geometry when reporting mass attenuation coefficients.