Kazakhstan is known as a country with a complex radioecological situation resulting from different sources such as a natural radiation background, extensive activities of the industrial system of the former Soviet Union and a well-known testing of nuclear power weapons occurred in the Semipalatinsk Test Site (STS) area. The present study focuses on the assessment of the background of dicentric chromosomes in Kazakhstan’s population, which is the starting point in the dose assessment of irradiated people, since the baseline level of spontaneous dicentrics can vary significantly in different populations. In this context, aiming to determine the background frequency of chromosome aberrations in the population of Kazakhstan, considering the heterogeneity of natural radiation background levels of its large territory, a selection of 40 control subjects living in four cities of North, South, West and East Kazakhstan was performed. The cytogenetic study on the selected groups showed fairly low background frequency values of chromosome aberrations (0.84 ± 0.83 per 1000 cells), comparable with other data in the literature on general populations, reporting background frequency values between 0.54 and 2.99 per 1000 cells. The obtained results should be taken into account when constructing the dose–effect calibration curve used in cytogenetic biodosimetry, as a “zero” dose point, which will reduce the uncertainty in quantifying the individual absorbed dose in emergency radiological situations.

Plutonium and trace elements and macroelements migration in the “soil–agricultural plant” system depending on soil moisture in the range from 15 to 40% of absolute soil moisture is studied in this vegetation experiment. The content of plutonium was analyzed by α-spectrometry with preliminary radiochemical isolation. The elemental composition was analyzed by the ICP-MS and ICP-AES methods. Beans (Fabaceae) of the Amber variety were used as the test culture. The plutonium transfer factor obtained in the vegetation experiments is in the range of 5.3 × 10^–4–1.5 × 10^–2, with an average value of 5.4 × 10^–3 for the aboveground part of the bean plants and a range of 4.5 × 10^–2 to 2.7 × 10^–1, with an average of 1.6 × 10^–1 for bean roots. It was determined that the distribution of plutonium and trace elements and macroelements in the vegetative organs of plants is not equal and the transfer factor of plutonium for the aboveground part of plants is lower than for the root part. It was established that the accumulation of plutonium and trace elements and macroelements, depending on the soil moisture, is different for the organs of beans. The dependence of plutonium accumulation by plants on the soil moisture is significantly higher than for other elements considered. A decrease in the coefficient of accumulation of plutonium in the aerial part of the beans is recorded with an increase in soil moisture up to two orders of magnitude. There is a trend towards a slight decrease in the accumulation coefficients of Fe, Mg, Mn, Cr, Mo, Ni, Co, and Cu. For the root system of beans, a clear dependence of the accumulation of the considered elements on soil moisture is not observed.

The relevance of this work is caused by the need to expand the methods of complex environmental studies to assess the quality of environmental objects in small communities. The study of the elemental composition of dust and aerosol depositions will provide the most complete picture of the quality status of the main natural components. Air aerosols are a complex dispersed system that includes particles smaller than 10 microns. These particles have both natural and man-made origin: finely dispersed dust particles of soil, plants, microorganisms, soot, ash, components of smoke emissions from boiler houses, industry, etc. Atmospheric air of small settlements remains poorly studied, there are no systematic data on the chemical composition of atmospheric pollutants, and therefore the relevance of this work is determined. The aim of the research is to determine the elemental composition of the solid phase of the snow cover of a small settlement Dolon. Objects: dust-aerosol deposition, particulate matter of air aerosols, snow cover, coal and ash. Techniques: mass spectrometric and atomic emission with inductively coupled plasma (MS-ISP, OES-ISP) Results. The elemental composition of snow melt water and solid phase of snow was studied. To determine the degree of volatility of chemical elements their coefficient of enrichment from coal to ash was calculated. The main zones with increased content of heavy metals in dust and aerosol depositions were determined. In the snow cover of the investigated territory a group of elements with high migratory capacity was revealed. Maps of the snow cover pollution of the Dolon settlement were constructed with identification of areas (halos of pollution) with increased content of the studied groups of elements.

Relevance of the research is caused by the necessity of obtaining up-to-date data on concentrations of chemical elements in the "water-soil-plant" system on the near-entry spot of tunnel 504 of "Degelen" site at the former Semipalatinsk Test Site. During flooding in spring, elements may be carried out beyond tunnel 504. The main aim of the research is to study spatial distribution of chemical elements in the "water-soil-plant" system in the streamflow of tunnel 504. To achieve this goal, the following tasks were set: 1) determine concentration levels of chemical elements in water; 2) study concentration levels of chemical elements in soil; 3) identify features of chemical elements accumulation in plants of tunnel 504. Methods. The ultimate composition of water was determined by inductively-coupled plasma mass-spectrometry (Elan 9000 "Perkin Elmer SCIEX"), inductively-coupled plasma atomic emission spectrometry ("iCAP 6300 Duo" Thermo Scientific). The analysis of such indicators as total mineralization, the content of sulfates, hydrocarbonates, chlorides, calcium, magnesium and sodium was carried out using titrimetric, colorimetric, potentiometric techniques in accordance with GOST. Results. The analysis of the data obtained for water showed a high content of such elements as Li, Be, Al, Mn, Zn, Rb, Sr, Cd, Cs, La, Ce, U the average content of which exceeds the clarke several times for groundwater of the arid climate (sulfate water). The excess of maximum permissible levels of such elements as Be (2800 MPC), Mn (260 MPC), Al (76 MPC), U (70 MPC) and Cd (50 MPC) has been registered for water. According to the latest data, the content of such elements as Li, Be, Al in water was found to increase by 2 times whereas that of Co, Ni and Cu - by dozens of times. Spatial distribution of elements of interest in soil of tunnel 504 is non-uniform. Most of elements are concentrated in soil to the north of the streamflow bed. An elevated content of such elements as Be, Mn, Cu, Zn, Mo, Cd, Cs, Pb and U was detected in this area exceeding the clarke of lithosphere. The high index of lithosphere clarke value excess was found for uranium concentration (1000 times). Comparison of findings for contaminated areas with values of maximum permissible concentrations of chemical elements in soil showed the excess for Pb (26 MPC), Mn and Cu (9 MPC). Chemical composition of water and soil of tunnel 504 is unique by the content of rare-earth elements. The average content of REE in water exceeds the clarke by thousand times in ground water of the arid climate and STS ground water. The excess of the maximum permissible concentration level of samarium was observed in water. Predominance of light REE is characteristic, with a pronounced cerium-lanthanum feature. This fact shows that metals in water originate from natural sources. For most plant species of tunnel 504 an elevated content of Be, Cd, Cs, Pb, U and a number of REE was detected in the contaminated area. Concentrations of elements of interest in such plant species as reed and bluejoint in areas being compared, varied insignificantly which is apparently attributed to some physiological and biochemical mechanisms that impede the intake. Based on the above, one can conclude that spatial distribution of elements at tunnel 504 is first of all related to chemical elements carried out by tunnel water. About ten elements exceeding clarke values and maximum permissible levels were detected in water of tunnel 504.

To assess the environmental impact of uranium mining operations in southern Kazakhstan, the elemental and radionuclide composition of soil samples collected from settlements in the Kyzylorda Region was investigated. The analysis was carried out using X-ray fluorescence (XRF) and gamma-ray spectrometry. Mean concentrations and variation ranges were determined for 28 chemical elements, including uranium, lead, antimony, and gamma-emitting radionuclides such as ¹³⁷Cs, ⁴⁰K, ²³²Th, ²³⁸U, ²²⁶Ra, ²¹⁰Pb, and ²⁴¹Am. The analysis of the specific activities of the artificial radionuclides ¹³⁷Cs and ²⁴¹Am was carried out in order to assess the influence of the Semipalatinsk Test Site on the soils of the study area. Based on the obtained data, heavy metal pollution indices, ecological risk indices, and radiological parameters were calculated to evaluate the potential environmental and human health impacts. Most elements were present at levels below average crustal abundances, suggesting limited anthropogenic influence. Slight exceedances for uranium, lead, and antimony are likely associated with regional geochemical features. Radiological assessment indicated that the radiation environment remains within internationally accepted limits. The lifetime cancer risk values for exposure of humans to natural radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs from soil at 1 m above ground level ranged from 0.19 × 10⁻³ to 0.30 × 10⁻³, with an average of 0.24 × 10⁻³. Nearly all sampling points remained below the risk threshold of 0.29 × 10⁻³, indicating minimal radiological hazard. The carcinogenic risk remained within the acceptable regulatory range for both adults (2.0 × 10⁻⁵) and children (4.4 × 10⁻⁵), whereas the non-carcinogenic hazard index for children (1.3) slightly exceeded the screening threshold of 1. This finding identifies children as the most sensitive receptor group under the conservative assumptions of the applied screening methodology. The study demonstrates the applicability of combined chemical and radiometric methods for comprehensive environmental assessments in uranium mining regions. The results are of interest both in terms of methodology and in understanding the local geochemical and radiological landscape.