Assessing radon hazard in drinking water: A comprehensive approach integrating deterministic and probabilistic methods with water consumption routines.

The research aimed to determine the spatiotemporal distribution patterns of radon activity concentrations in tap water of Yerevan city and assess radon-associated hazards using both deterministic and probabilistic approaches. This was accomplished by integrating one-year monitoring data of radon in water with water consumption habits among adult population clusters, which were identified through food frequency questionnaire in Yerevan. The study findings indicated variations in radon activity levels across administrative districts. The highest average activity concentrations were detected in Davtashen (7.07 Bq/L), while the lowest average was observed in Kanaker-Zeytun (1.57 Bq/L). The overall pattern of spatiotemporal variation during monitoring period revealed higher prevalence of radon in water in the northern and western parts of the city compared to the east and south, indicating different sources of drinking water. The radon-associated hazard assessment from water, using a deterministic approach (e.g., inhalation, ingestion, radon dissolution in blood, total effective dose), revealed values below the individual dose criterion (IDC) of 0.1 mSv/y. Monte Carlo simulation revealed a probability of exceeding IDC in specific water consumption-based groups. Residents of Yerevan who drink more than 3 L water daily with the highest observed activity concentration of 11.4 Bq/L, have an 86.26 % chance of exceeding IDC. Residents consuming 2.1 L water daily have a 7.02 % chance of exceeding IDC. The study highlights the importance of applied principles and methodologies for radon monitoring, particularly considering actual water consumption data and different risk assessment approaches. Considering the worst-case scenario results, it is recommended to keep tap water consumption up to 3 L per day, keeping the tap open longer to reduce radon levels. It also emphasizes the need for continued monitoring, given the variations in radon activity. The study provides valuable insights into radon exposure assessment, mitigation, and action plans in terms of water safety and public health.

The spatiotemporal variation, background, and baseline activities of radionuclides in the soil of Aragats Massif (Armenia).

The present study was performed to reveal the distribution patterns and spatiotemporal changes of radionuclides in the soil of the highest mountain of Armenia: Aragats Massif. In this regard, two surveys were implemented in 2016-2018 and 2021 with an altitudinal sampling strategy. The activities of radionuclides were determined by gamma spectrometry system with HPGe detector (CANBERRA). Correlation and linear regression analysis were applied to determine the dependence of radionuclides' distribution from altitude. Classical and robust statistical methods were used to assess the local background and baseline values. In two sampling profiles, the spatiotemporal variation of radionuclides was studied. A significant correlation was revealed between 137Cs and altitude pointing to global atmospheric migration as a primary source of 137Cs in Armenian environment. The predicted values of regression model revealed a 0.08-Bq/kg and 0.03-Bq/kg increase of 137Cs in each m on average, for the old and new survey, respectively. The assessment of background activities of NOR (naturally occurring radionuclides) enables setting the local background for 226Ra, 232Th, and 40 K in soils of Aragats Massif: 831.3 ± 20.2 Bq/kg and 540.6 ± 18.3 Bq/kg for 40 K, 85.5 ± 3.1 Bq/kg and 27.7 ± 2.6 Bq/kg for 226Ra, and 66.8 ± 3.2 and 46.4 ± 3.0 Bq/kg for 232Th, respectively, for the years of 2016-2018 and 2021. 137Cs baseline activity was estimated by altitude: 350 ± 3.7 Bq/kg and 108 ± 2.5 Bq/kg, respectively, for the years of 2016-2018 and 2021.

Multifractal features of activity concentration and stochastic risk assessment of naturally occurring and technogenic radionuclides in the soil of Yerevan, Armenia.

Spatial patterns and background ranges of naturally occurring radionuclides (NORs) (i.e. U-238, Th-232, K-40) and Cs-137 were studied in the urban soils of Yerevan, the capital city of Armenia. Multifractal Inverse Distance Weighting (MIDW) was used to generate and analyze distribution patterns of radionuclide activities. Based on Fourier transformation of radioactivity data, a spectral analysis was also applied to separate, where possible, background/baseline patterns from local anomalies: two ranges of background values were found to characterise the Yerevan territory. Specifically, in the south and south-east of Yerevan, the lower background ranges of U-238, Th-232 and K-40 comprised in the intervals 2.60-36.42 Bq/kg, 4.04-30.63 Bq/kg and 147.7-396.7 Bq/kg, respectively, were observed in association with the presence of sedimentary formations. In contrast, the higher ones were found, instead, in the central and northern parts of the city where andesite-basalt lavas and ignimbrite tuffs occur. Here, the background values rise to 142.4 Bq/kg, 138.76 Bq/kg and 1502 Bq/kg, respectively. As for the distribution of artificial Cs-137, its baseline levels in Yerevan seem to depend mostly on the global radioactive fallout and some local technogenic sources. Its distribution patterns partially differ from those of NORs. In the framework of this paper, Radium equivalent activity (RaEq), outdoor absorbed dose rate in air (ODRA) and annual effective dose equivalent (AEDEs) were also determined and mapped. They show a good coincidence of their spatial variations with those of NORs. The Monte Carlo simulation was used to assess excess lifetime cancer risk from a stochastic perspective. The related sensitivity analysis revealed that, among NORs, U-238 and Th-232 give the greatest contribution to the total variance (45.7% 42.8%, respectively). In comparison, K-40 has the lowest share (11.3%). Regarding Cs-137, a highly negligible contribution to the onset of health risks (accounting for 0.02%) was observed.

Evolution of radioecology in Armenia: a short review.

PURPOSE: The article generalizes the evolution of radioecological studies conducted by female scientists in Armenia in the period of 1950-2020. Radioecological studies were launched in 1958, prior to the construction of the ANPP and major nuclear disasters. CONCLUSION: The obtained results allowed the revealing peculiarities of distribution and accumulation of naturally occurring radioactive materials (NORM) and artificial radionuclides in the natural environment, urban sites and industrial centers. Series of national environmental monitoring programs were designed in order to reveal the main migration pathways of NORM and artificial radionuclides, as well as the assessment of exposure to natural and induced radiation.

Identification of radionuclides' altitudinal distribution In soil and mosses In highlands of Armenia.

The present study was conducted in mountain regions of Armenia with the aim to assess the activity concentrations of natural K-40 and artificial Cs-137 in soil and mosses and reveal the distribution similarities and differences. Most widespread moss species and surface soils were sampled concurrently from eight mountain ridges and massifs by different altitudinal belts. Statistical analysis revealed significant differences and opposite characteristics for K-40 and Cs-137. In case of K-40 the activity concentrations decreased in mosses by altitude but with no significant correlation. The mean activity concentrations of K-40 in the soils of different altitudinal belts are close, nevertheless, the higher activity concentrations are common for soils derived from ingenious rocks. For Cs-137 in mosses, the correlation with altitude is statistically insignificant, but the altitudinal dependence is noticeable within separate ridges and massifs. A significant correlation was identified between Cs-137 in soil, altitude and precipitation rate. Studying natural K-40 and artificial Cs-137 radionuclides together yielded interesting contrasting results confirming the dissimilar behaviour of radionuclides with different origins in the environment.

Yerevan soil radioactivity: Radiological and geochemical assessment.

Spatial pattern of naturally occurring radionuclides (NOR): 226Ra, 232Th, 40K, and artificial 137Cs was studied using soil samples of the multipurpose geochemical survey of the city of Yerevan, capital of Armenia. High purity Ge detector-based gamma spectrometry system was used for the determination of radionuclides activity concentrations in urban soils. A combination of compositional data analysis, geochemical mapping and radiological assessment were applied to reveal potential factors of technologically enhanced natural radioactivity and excess lifetime cancer risk for Yerevan's population due to NOR and artificial 137Cs in the urban environment. Statistical methods with the geochemical mapping revealed the great contribution of soil-forming rocks to NOR distribution in urban soils. The spatial distribution of calculated radiological indices and dose rates levels follows the distribution patterns of NOR. The activity concentration of fallout radionuclide 137Cs was within the range typical for the studied altitudes. Above baseline activity of 137Cs was observed in the north-western and western part of the city that is in typical ranges of 137Cs content in soil derived from global radioactive fallout. Urban soils of Yerevan were found radiologically safe, however, igneous rock derived soils are a sink of NOR and the main environmental source of continuous exposure to the residents. Values of excess lifetime cancer risk were higher than mean global value.

Natural radioactivity in urban soils of mining centers in Armenia: Dose rate and risk assessment.

Soil radioactivity levels, dose rate and radiological health risk were assessed in metal mining centers of Armenia, at the towns of Kapan and Kajaran. Archive soil samples of the multipurpose soil surveys implemented in Kapan and Kajaran were used for estimation of total alpha and total beta activity levels using gas-less iMatic™ alpha/beta cօunting system (Canberra). Ten representative soil samples per town were randomly selected from different urban zones for naturally occurring radionuclide measurements (238U, 232Th, 40 K) using high purity germanium detector. Four radiological indices: radium equivalent activity, outdoor absorbed dose rate, annual effective dose equivalent and excess lifetime cancer risk were estimated based on naturally occurring radionuclide activity concentrations in soils. Results suggest that in Kapan the soil radioactivity, although enhanced by copper and gold-polymetallic mining, are not a significant risk factor to human health. In Kajaran, the soil radioactivity levels were above the background and world average values provided by UNSCEAR, but radionuclides originated in a natural geogenic source and not from mining activities. Generally, in this region no significant radiological risks were identified in relationship with molybdenum, copper, and gold-polymetallic ore mining.