Search Results (6)

Wildfires frequently occur in Ukraine during agricultural open-burning seasons in spring and autumn. High aerosol concentrations from fire emissions can significantly affect meteorological processes via direct and indirect aerosol effects. To study these impacts, we selected a severe wildfire episode from April 2020 in the Chornobyl Exclusion Zone (CEZ) and its surrounding area as a case study. We employed the Enviro-HIRLAM modeling system to simulate reference (REF) meteorological conditions, along with direct (DAE), indirect (IDAE), and combined (COMB) aerosol effects. In our simulations, black carbon (BC) and organic carbon (OC) comprised 70–80% of all aerosol mass in the region, represented in two layers of higher concentrations: one near the surface and the other 3–4 km above the surface. Our simulations showed that the inclusion of aerosol effects into the modeling framework led to colder (up to −3 °C) and drier (relative humidity drop up to −20%) conditions near the surface. We also observed localized changes in cloudiness, precipitation (mainly redistribution), and wind speed (up to ±4 m/s), particularly during the movement of atmospheric cold fronts. Larger uncertainties were observed in coarser model simulations when direct aerosol effects were considered. Quantifying the aerosol effects is crucial for predicting and promptly detecting changes that could exacerbate unfavorable weather conditions and wildfires. Such knowledge is essential for improving the effectiveness of emergency response measures. Full article

This paper presents historical and evolutionary insights into the “tarpan” group of small horses by examining molar tooth enamel ultrastructure. Mathematical methodologies were applied to enhance the analysis. Tooth enamel from species such as Equus gmelini (tarpan), E. latipes, and E. hydruntinus from Pleistocene Ukrainian localities, E. przewalskii from the Chornobyl Exclusion Zone in Ukraine, and E. caballus form sylvaticus (Polish konik) from Roztocze National Park, Poland, underwent scanning microscope examination. Measurements of enamel structures, including prisms (PE) and interprismatic matrix (IPM), were conducted, with the K-index used as their ratio, categorized by enamel type (I, II, III). The findings confirmed that the crystal structures of enamel in these horse groups vary based on genus evolution, diet, and environmental conditions, shaping the enamel’s morphological features. Through analysis, clusters were identified, allowing for potential reconstructions of relationships among study groups. The results revealed distinct differences between species, enabling their classification within an established phenogram. Two primary clusters emerged: one consisting of extinct small horse forms from diverse localities and another grouping modern forms. Notably, the Late Pleistocene European species E. latipes showed close affinities to the latter cluster. Full article

This study investigated the content of ¹³⁷Cs (a long-lived radioactive isotope of caesium) in various parts of Pinus sylvestris L. (Scotch pine) and Dicranum polysetum Sw. (rugose fork-moss) at three different sites within the exclusion zone of the Chornobyl nuclear power plant over two years. The Leliv site is located within the 10 km zone, while the Paryshiv and Dytiatky sampling sites are within the 30 km zone. Samples of different P. sylvestris organs were collected, including 1- and 2-year-old branches and needles and wood and outer bark, and the entire D. polysetum. Sampling was conducted every two weeks throughout the year during 2014 and 2015. The specific activity levels of ¹³⁷Cs in the samples were measured using gamma spectrometry with a CANBERRA gamma spectrometer unit and a coaxial high-purity HPGe semiconductor detector. The study found that at the Leliv and Paryshiv sites, the highest content of ¹³⁷Cs in living organs of P. sylvestris was found in the wood. At the Dytiatky site, the needles and branches of the first and second years had anomalously high concentrations of radiocaesium (¹³⁷Cs). This could be due to a thin layer of forest litter (1.5 cm) at that site. The study also found significant changes in the specific activity levels of ¹³⁷Cs in living pine organs throughout the year. The highest concentration was observed in pine branches and needles in summer, and the maximum values in wood were observed in winter. The study suggests that a constant circulation of ¹³⁷Cs in the soil–plant system can cause seasonal changes in the content of ¹³⁷Cs in living pine organs. Symbiotic mycorrhizal fungi can play an important role in the circulation of radiocaesium in forest ecosystems. The outer bark of P. sylvestris did not show any seasonal changes in the content of ¹³⁷Cs. It may not be involved in radiocaesium redistribution inside the plant but can serve as a long-term source of this radionuclide entering the forest litter. The study found no seasonal changes in the accumulation of ¹³⁷Cs by D. polysetum, which might be due to the physiological characteristics of this plant species. Based on the analysis of the conducted studies, the recommendation is to consider the seasonal changes in the content of ¹³⁷Cs during monitoring activities and when using Scots pine in areas potentially contaminated with this radionuclide. Full article

The “Chernobyl nuclear disaster” released huge amounts of radionuclides, which are still detectable in plants and sediments today. Bryophytes (mosses) are primitive land plants lacking roots and protective cuticles and therefore readily accumulate multiple contaminants, including metals and radionuclides. This study quantifies ¹³⁷Cs and ²⁴¹Am in moss samples from the cooling pond of the power plant, the surrounding woodland and the city of Prypiat. Activity concentrations of up to 297 Bq/g (¹³⁷Cs) and 0.43 Bq/g (²⁴¹Am) were found. ¹³⁷Cs contents were significantly higher at the cooling pond, where ²⁴¹Am was not detectable. Distance to the damaged reactor, amount of original fallout, presence of vascular tissue in the stem or taxonomy were of little importance. Mosses seem to absorb radionuclides rather indiscriminately, if available. More than 30 years after the disaster, ¹³⁷Cs was washed out from the very top layer of the soil, where it is no more accessible for rootless mosses but possibly for higher plants. On the other hand, ¹³⁷Cs still remains solved and accessible in the cooling pond. However, ²⁴¹Am remained adsorbed to the topsoil, thus accessible to terrestrial mosses, but precipitated in the sapropel of the cooling pond. Full article

The ecological half-life of ¹³⁷Cs was calculated individually for four symbiotrophic fungi species (Boletus edulis, Imleria badia, Suillus luteus, Paxillus involutus) at 10 sampling sites in the Chornobyl exclusion zone and in the Kyiv region. It was found that the maximum rate of excretion of 137Cs from the fungi organisms is characteristic for the territory with the maximum levels of soil contamination, i.e., for a zone near Chornobyl Nuclear Power Plant. In areas with low ¹³⁷Cs content, a slowing down of the excretion rate predominates. These results reveal different fungal response to the distinct concentration levels of ¹³⁷Cs in forest ecosystems. This observation further suggests that radiocaesium can be selectively accumulated by fungi and used in their life processes. Presence of this ¹³⁷Cs retention mechanism in fungi leads to a longer contamination of woody plants-symbionts. Full article

The consequences of the Chernobyl disaster continue to threaten humans and ecosystems across fallout gradient in Northern Ukraine and nearby. Forest ecosystems contain substantial stocks of long-lived radionuclide ⁹⁰Sr which was leached from the fuel matrix during the disaster. Nowadays, there is a lack of information about current transfer factors (TF) of this radionuclide from soil to the stemwood of native tree species. We have estimated ⁹⁰Sr content in the forest stemwood of three tree species utilizing models of their growth and yield and collected woody samplings. TFs provided here vary greatly across studied tree species (18.0 × 2.1^±1, 8.7 × 2.8^±1, and 10.4 × 6.0^±1 n × 10⁻³ m²·kg⁻¹ (geometrical mean (GM) ± geometrical standard deviation, GSD) for the above species, respectively) and together with indicators of soil contamination allow us to reliably assess local stocks in the stemwood. Silver birch stands are estimated to deposit the highest ⁹⁰Sr stocks. Herewith, at 25 years old Black alder stands could accumulate higher stocks (up to 35 MBq·ha⁻¹) under rich growth conditions. TFs obtained in this study substantially exceed values provided by the International Atomic Energy Agency for studied tree species and thus could entail respective restrictions on use of firewood across large areas in Ukrainian Polissya. Data provided here may be harnessed to support decisions of respective stakeholders to provide credibly safe management of the contaminated forest ecosystems. Full article