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

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.

Mosses in the Kopački Rit Nature Park, Croatia, as bioindicators of a potential radioactive contamination of the middle Danube River basin

We studied activity concentrations of radionuclides in the Kopački Rit Nature Park using mosses as bioindicators. This area of intact nature is at the tripoint of Croatia, Hungary, and Serbia, being located basically at the centre of the middle Danube River basin. Therefore, it can be easily affected by airborne pollution from various locations in the Middle Europe and beyond. The goal of our research was to assess whether the Park could serve as a location where any new radioactive contamination could be sensitively detected, which implied a necessity for low activity concentrations at the present time. Our gamma-ray spectrometry revealed the presence of only one anthropogenic gamma emitter, that is, ¹³⁷Cs. Its activity concentration in the mosses ranged from 0.7 to 13.1 Bq kg⁻¹, being low indeed. Another radionuclide in our focus was ²¹⁰Pb. Generally, its elevated concentrations may signify ecologically undesirable human activities that involve naturally occurring radioactive matter. The activity concentration of ²¹⁰Pb in the mosses was in the range from 183 to 690 Bq kg⁻¹. This did not depart from the results of other similar studies and was again low enough for a detection of possible excess amounts of this radionuclide in the future.

137Cs and 40K activity concentrations in edible wild mushrooms from China regions during the 2014–2016 period

Introduction. Contamination by radiocaesium of edible wild mushrooms after major nuclear accidents is a long-lasting process in some regions of the world. Following greater awareness of radioactive pollution in Asia, particularly after the Fukushima accident, this study investigated the radioactivity of 137Cs and 40K contamination in edible wild mushrooms in China. Study objects and methods. The objects of the research were edible wild mushrooms collected during 2014 to 2016, from the Inner Mongolian and Yunnan regions of China. To obtain an insight into any environmental impacts to distant regions of mainland Asia, the mushrooms were analyzed for 137Cs activity. In parallel, the natural activity of 40K was also determined and used to estimate the content of total K. The topsoil underneath the mushrooms was also investigated from a few sites in Bayanhushu in Inner Mongolia in 2015. Results and discussion. The results showed that in 4 to 6 mushrooming seasons after the accident, mushrooms from both regions were only slightly contaminated with 137Cs, which implied negligible consequences. The activity concentrations of 137Cs in dried caps and whole mushrooms in 63 of 70 lots from 26 locations were well below 20 Bq kg–1 dry weight. Two species (Lactarius hygrophoroides L. and Lactarius volemus L.), from Jiulongchi in Yuxi prefecture showed higher 137Cs activities, from 130 ± 5 to 210 ± 13 Bq kg–1 dw in the caps. 40K activities of mushrooms were around two- to three-fold higher. A composite sample of topsoil (0–10 cm layer) from the Bayanhushu site (altitude 920 m a.s.l.) in Inner Mongolia showed 137Cs activity concentration at a low level of 6.8 ± 0.7 Bq kg–1 dw, but it was relatively rich in potassium (40K of 595 ± 41 Bq kg–1 and total K of 17000 ± 1000 mg kg–1 dw). Conclusion. Wild mushrooms from the Yunnan and Inner Mongolia lands only slightly affected with radioactivity from artificial 137Cs. Lack of 134Cs showed negligible impact from Fukushima fallout. Ionizing radiation dose from 137Cs in potential meals was a fraction of 40K radioactivity. The associated dietary exposure to ionizing irradiation from 137Cs and 40K contained in mushrooms from the regions studied was considered negligible and low, respectively. Mushroom species examined in this study are a potentially good source of dietary potassium.

Radiocaesium in Tricholoma spp. from the Northern Hemisphere in 1971-2016

A considerable amount of data has been published on the accumulation of radiocaesium (¹³⁴Cs and particularly, ¹³⁷Cs) in wild fungi since the first anthropogenically influenced releases into the environment due to nuclear weapon testing, usage and subsequently from major accidents at nuclear power plants in Chernobyl (1986) and Fukushima (2011). Wild fungi are particularly susceptible to accumulation of radiocaesium and contamination persists for decades after pollution events. Macromycetes (fruiting bodies, popularly called mushrooms) of the edible fungal species are an important part of the human and forest animal food-webs in many global locations. This review discusses published occurrences of ¹³⁴Cs and ¹³⁷Cs in twenty four species of Tricholoma mushrooms sourced from the Northern Hemisphere over the last five decades, but also includes some recent data from Italy and Poland. Tricholoma are an ectomycorrhizal species and the interval for contamination to permeate to lower soils layers which host their mycelial networks, results in a delayed manifestation of radioactivity. Available data from Poland, over similar periods, may suggest species selective differences in accumulation, with some fruiting bodies, e.g. T. portentosum, showing lower activity levels relative to others, e.g. T. equestre. Species like T. album, T. sulphurescens and T. terreum also show higher accumulation of radiocaesium, but reported observations are few. The uneven spatial distribution of the data combined with a limited number of observations make it difficult to decipher any temporal contamination patterns from the observations in Polish regions. When data from other European sites is included, a similar variability of ¹³⁷Cs activity is apparent but the more recent Ukrainian data appears to show relatively lower activities. ⁴⁰K activity in mushrooms which is associated with essential potassium, remains relatively constant. Further monitoring of ¹³⁷Cs activity in wild mushrooms would help to consolidate these observations.

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.