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Article

Specific Activity of Radionuclides in Cryoconite Sediments of Glaciers of the Central Caucasus (Tsey, Skazka, Bezengi), Russia

by
Rustam Tembotov
1,2,*,
Albert Gangapshev
3,
Ali Gezhaev
3 and
Evgeny Abakumov
2,4
1
Laboratory of Soil-Ecological Research, Tembotov Institute of Ecology of Mountain Territories RAS, 360051 Nalchik, Russia
2
Department of Applied Ecology, Faculty of Biology, St. Petersburg State University, 199034 Saint Petersburg, Russia
3
Institute for Nuclear Research RAS, 361609 Moscow, Russia
4
All-Russian Research Institute for Agricultural Microbiology, 196608 Pushkin, Russia
*
Author to whom correspondence should be addressed.
Earth 2025, 6(2), 60; https://doi.org/10.3390/earth6020060
Submission received: 30 May 2025 / Revised: 13 June 2025 / Accepted: 14 June 2025 / Published: 17 June 2025
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Abstract

:
Nowadays, much attention has been paid to the study of the specific activity of radionuclides on the surface of glaciers. This work is devoted to the study of specific activity of natural (K-40, U-235, U-238, Th-232) and anthropogenic (Cs-137) radionuclides in cryoconites of glaciers of the Central Caucasus. The work shows that the activity of the investigated natural radionuclides in the cryoconites of the glaciers we studied is comparable to data from Arctic glaciers, somewhat lower than on Mount Elbrus and Transcaucasia, and significantly lower than on Alpine glaciers. The study revealed that the glaciers of the Central Caucasus (Tsey, Skazka, and Bezengi) exhibit low values of specific activity of anthropogenic radionuclide Cs-137 and average from 0.51 Bq/kg (Bezengi) to 2.61 Bq/kg (Skazka). On the contrary, high and very high concentrations of this radionuclide were revealed in cryoconites of glaciers from other regions, especially in the Alps, the Arctic, and Transcaucasia. Thus, our data confirm the results of previous studies conducted on glaciers of the Central Caucasus, which indicated that the activity of natural radionuclides in cryoconites of glaciers of the Central Caucasus is comparable to the world average values, while the anthropogenic radionuclide Cs-137 is much lower.

1. Introduction

The environment contains radioactive substances called natural radionuclides, which include radionuclides whose sources are terrestrial and cosmic radiation. Terrestrial radiation is the combined emission of radionuclides contained in rocks, soil, water, and air. The largest portion of natural radionuclides is contained in granite rocks and volcanic sediments [1]. Natural radionuclides of terrestrial origin include decay products of U-238 (radioactive family of uranium), U-235 (radioactive family of actinic uranium), Th-232 (radioactive family of thorium), and K-40 (radioactive potassium). Their content and distribution are influenced by climatic peculiarities of regions, landforms, and other various factors. The content of natural radionuclides is determined when assessing the radioactivity of the environment and for studies of their transport and migration processes in ecosystems [2]. With the advent of nuclear weapons and nuclear power, anthropogenic radionuclides, which enter the environment due to human activities, have been added to them [3,4]. The sources of anthropogenic radionuclides include industrial enterprises of the nuclear fuel complex, consequences of radiation accidents, nuclear weapons tests, etc. Thus, since the middle of the 20th century, several thousand experiments with the use of nuclear weapons have been conducted on the Earth [5], which have made a significant contribution to the radioactive contamination of ecosystems. Also, the Chernobyl nuclear power plant accident of April 1986 in the Soviet Union resulted in a huge contribution to the spread of anthropogenic radionuclides. As a result of such explosions and accidents, radioactive substances were trapped in the atmosphere and stratosphere and then transported by wind over long distances, gradually deposited around the globe. To assess the contamination of the Earth’s surface, the anthropogenic radionuclide Cs-137 is of greatest interest. This is due to the fact that Cs-137 contributes significantly to the lifetime effective dose of external and internal exposure of humans and, due to its chemical similarity to K+, can enter the human body through the food chain and substitute potassium during transportation in the cell membrane [1]. Although the specific activity of Cs-137 is quite low in most areas of the Earth, the influence of transcontinental transport of dusty substances may lead to an increase in the specific activity of radiocaesium in ecosystems [6].
At present, one of the most important problems of mankind is climate change, which leads to an increase in global and local temperatures, a decrease in precipitation, increased desertification, and enormously rapid deglaciation [7]. Active deglaciation is observed in almost all polar and mountain regions: Antarctica [8], Arctic [9], Tibetan Plateau [10], Alps [11], and numerous others. In addition, active deglaciation occurs in the Caucasus [12,13]. Although global climate change is the main cause of glacier deglaciation worldwide, the presence of cryoconite deposits may accelerate this process [14]. Cryoconite is a dark-colored organomineral sediment ubiquitous on the surface of glaciers, which is composed of bacteria, archaea, fungi, and algae, with the greatest contribution being made by cyanobacteria, which form films and filaments during the ablation season, contributing to the formation of aggregates composed of mineral deposits and organic matter [15]. Various studies have shown [16,17] that cryoconite effectively accumulates contaminants, including radionuclides. Continued intensive deglaciation will release radionuclides from cryoconites on the surface of glaciers, and they will enter downstream rivers, which in turn may affect ecosystems and human health [18].
The Caucasus Mountains contain the largest glacial system in Russia, covering an area of about 450,000 km2 and a length of about 1500 km. According to its physical and geographical characteristics, the Greater Caucasus is normally subdivided into the Eastern, Central, and Western Caucasus. The Central Caucasus is the highest among them, with absolute altitudes up to 5000–5600 m [12]. In recent years, various studies have been conducted on glaciers of the Central Caucasus to investigate the contamination of cryoconites with various chemicals [19,20]. In the works [21,22] on the study of cryoconites from the glaciers of Mount Elbrus in the Central Caucasus, it was shown that they also accumulate both natural and anthropogenic radionuclides. In [12], it was shown that during 1986–2018, the glaciation of the Caucasus decreased by 415 km2 (0.87% per year), and since the beginning of the 20th century, glaciers have decreased by 46%. Nowadays, active glacier degradation continues in the Central Caucasus, as in the whole Caucasus [23]. With the observed retreat of high-mountain glaciers in the Central Caucasus, the active transport of pollutants, including radionuclides, can significantly affect the radioactive contamination of mountainous areas.
Based on all of the above, the purpose of this work was to assess and analyze the specific activity of radionuclides in cryoconites of previously unexplored glaciers of the Central Caucasus—Tsey, Skazka, and Bezengi. To achieve this goal, several objectives were formulated: (1) to determine the specific activity of natural radionuclides (K-40, U-235, U-238, Th-232); (2) to determine the specific activity of anthropogenic radionuclide Cs-137; and (3) to compare our data with the results for other regions of the Earth, according to literature sources.

2. Materials and Methods

2.1. Study Areas

The Caucasus Mountains represents the largest glacial system in Russia, extending from the Black Sea to the Caspian Sea. About 70% of the Caucasus glaciation belongs to the Central Caucasus [12]. We have studied several valley glaciers of the Central Caucasus: Tsey and Skazka (Republic of North Ostetia–Alania) and Bezengi (Kabardino-Balkar Republic) (Figure 1).
Thus, the study of cryoconite radioactivity on glaciers of the Russian Caucasus has been carried out only on the glaciers of Mount Elbrus, so one of the objectives of this study was to expand the geography of such studies. The choice of the Tsey and Skazka glaciers for the investigations is due to the fact that these glaciers are located in close proximity to each other, but they are subject to different anthropogenic impacts (the Tsey glacier is located in an area with a specially protected regime, and the Skazka glacier is located in an area with intensive recreational activities). The relevance of the Bezengi glacier for the study is explained by the fact that it is the largest glacier in the Central Caucasus. These glaciers were previously studied for various pollutants in cryoconites, including heavy metals, while radioactivity was not studied. Valley glaciers were chosen because when these glaciers melt, radionuclides accumulated in cryoconites can get into mountain rivers and carry them to downstream ecosystems, accumulate in glacial ecosystems, and enter the human body through vegetation or animals.
The Tsey glacier is one of the largest glaciers in the Central Caucasus (area of about 10 km2). The glacier is located in the Adai-Khokh mountain massif on the northern macro-slope of the Greater Caucasus. It feeds the Tseydon River, which flows through the Tsey Gorge [24]. The Tsey glacier has been actively retreating over the last century. Thus, since the mid-19th century, it has shrunk by 1.9 km in length and 1.7 km2 in area, while the end of the glacier has risen by 250 m [25]. As the glacier retreats, meadow vegetation communities are formed in place of bare glacial areas, shrub communities are already forming in areas 10–14 years old, and forest communities are forming in areas 30–35 years old. The Skazka glacier is located in the upper part of the Skazka Gorge, located next to the Tsey Gorge, on a pass 3800 m above sea level, between the Lagau and Adai-Khokh mountains. The glacier is about 3 km long and its tongue descends to heights of 2400 m. Since the end of the 19th century, the lower edge of the Tale glacier has risen about 700 m. The Skazdon River flows from the glacier and flows down the gorge and into the Terek, the largest river in the Caucasus. The climate of the Tsey and Skazka gorges is temperate continental, with precipitation prevailing in spring and summer, but heavy snowfalls most often occur in the second half of winter and early spring. The warmest month is July, and the coldest is February, with average monthly temperatures of 12.7 °C and −8.8 °C, respectively. The average annual precipitation is about 800 mm [25].
Bezengi is the largest valley glacier in the Caucasus. This glacier is surrounded by high valley walls and ends in a powerful terminal moraine. The Bezengi glacier feeds the Cherek-Khulamsky River, which flows through the Khulamo-Bezengi Gorge below. The Bezengi glacier has retreated more than 2.5 km from the early to mid-19th century to 2011 and is shrinking by an average of 23,000 m2 per year [26]. The climate of the Bezengi Gorge is strongly influenced by the west-eastern transport of free atmosphere, due to which westerly winds prevail at high altitudes. Taking into account the fact that a significant area of the upper gorge is occupied by glaciers, glaciation has a great influence on the climate here. The average annual temperature in the high-mountainous part of the Bezengi Gorge is −4.7 °C. Average precipitation varies from 900 to 1400 mm/year, in some years reaching up to 2373 mm/year [20].

2.2. Sampling Strategy

In August 2023, cryoconites were sampled from the surface of the valley glaciers of the Central Caucasus—Tsey, Skazka, and Bezengi (Figure 2).
Using a stainless steel spatula, 3 cryoconite samples were collected from the ablation zone of each of the studied glaciers, as this material is likely to enter the glacial zone given the ongoing melting. Cryoconite samples were scraped from the ice, placed in clean zipper-locked specimen bags, and sealed. The dry weight of the samples ranged from 307 to 370 g. In the laboratory, the collected cryoconite samples were evaporated and dried at a temperature of 105 °C. Since the samples were sufficiently homogeneous, no sieving was required. Descriptions of the sampling locations are presented in Table 1.

2.3. Gamma Spectrometry

The specific activity of radionuclides in the samples was measured in the low-background mode, on a gamma-spectrometer made of ultrapure germanium with a registration efficiency of 20% (according to ANSI/IEEE 325-1996 specification), located in the underground laboratory of the Baksan neutrino observatory of the Institute of Nuclear Research of the Russian Academy of Sciences. A full description of the instrument is presented in [21]. Detectors made of ultrapure germanium have been used in various studies [27,28] and have shown their efficiency. The samples were analyzed in triplicate. The measurement time for each sample was 100 h. Using the MCC-MT software package (https://www.tals.eu/mcc-mt (accessed on 6 May 2025)), the number of registered specific gamma-quanta per decay for each nuclide was calculated using the Monte Carlo method. MCC-MT is a program for simulating three-dimensional modeling of ionizing radiation transmission and registration processes. In the model, nuclides were homogeneously distributed in the sample. The value of k was determined by the results of drawing simulation 106 decays of radionuclide in the studied cryoconite sample. This software package supplied with low-background gamma spectrometers is the equivalent of the GEANT-4 package, which is widely used in various studies [29,30]. The number of events in the total absorption peak S was defined by fitting with a Gaussian. The validity of the measurements calculation was checked using a sample with known activity of radionuclides in it. In our case, we measured the activity of isotope K-40 in a sample of potassium dichromate (K2Cr2O7).

2.4. Statistical Processing of Data

Statistical calculations were performed using the Statistica 12.0 program. The reliability of the difference between the studied radionuclides of the compared sites was evaluated using Student’s t-criterion at the significance level p ≤ 0.05.
The efficiency of γ-quantum registration from radionuclide decays was calculated using the MSS-MT program package. The spectra were constructed and processed in the SciDAVIS program.

3. Results and Discussions

3.1. Specific Activity of Natural Radionuclides in Cryoconites

The results of gamma spectrometric analysis showed that all spectra contain γ lines from K-40 decays, U-238, U-235, and Th-232 decay chains. The activity of K-40 was determined by the 1460.8 keV line, U-238 by the 351.9 keV line, U-235 by the 143.8 keV line, and Th-232 by the 238.6 keV line. For example, the gamma-ray spectra of sample Tsey-3 (the one with the lowest activity) compared to the background of the HPGe gamma spectrometer are presented in Figure 3. It can be seen that the background of the detector is negligible compared to the activity of the samples. In the spectra, one can observe specific peaks from gamma rays from the decay of various radionuclides: K-40—1460.8 keV and the U-238 chain—186.2 keV (Ra-226), 351.9 keV (Pb-214), and 295.2 keV (Pb-214). The Th-232 chain includes peaks at 911.2 keV (Ac-228) and 969.0 keV (Th-230), as well as 238.6 keV (Pb-212) and 583.2 keV (Tl-208). Peaks from the U-235 chain are difficult to see due to its lower activity. The background spectrum also shows two peaks at 1332.5 and 1173.3 keV from the cosmogenic radionuclide Co-60 in the passive shielding of the detector.
The data presented in the table (Table 2) show that the specific activity of the studied natural radionuclides within one glacier in different cryoconite samples is not the same. The coefficient of variation of the studied natural radionuclides in cryoconites of the studied glaciers, depending on the radionuclide, is within the range of low to average values and, for Tsey, ranges from 1% to 17%, for Skazka, from 1% to 16%, and for Bezengi, from 4% to 20%.
A comparison of average values of specific activity of the studied natural radionuclides (K-40, U-238, U-235, and Th-232) on the glaciers we investigated showed some differences (see Table 2). Thus, when comparing the territorially close to each other Tsey and Skazka glaciers, it was found that the activity of the studied natural radionuclides is higher in cryoconites of the Skazka glacier, except for radionuclide U-235. Statistically significant differences in activity were found for radionuclides K-40 (t = 10.1, p = 0.000) and Th-232 (t = 7.0, p = 0.002). A comparison of the activity of the studied natural radionuclides in cryoconites of the most remote Bezengi glacier with those of the Tsey and Skazka glaciers showed that in Bezengi, they have higher values, except for the activity of Th-232, which was higher in the Skazka glacier. Statistically significant differences were found only for radionuclide K-40 (t = 7.4, p = 0.002). Thus, it was revealed that although some differences in the activity of the studied natural radionuclides were observed in cryoconites of the glaciers studied by us, but still these differences are not significant, and statistically significant changes were found only for radionuclide K-40.
In order to compare the specific activity of natural radionuclides in cryoconites of glaciers from other regions of the Earth with the data obtained by us, the literature was analyzed. It was found that the natural radionuclides that are mainly determined in glacier cryoconites are K-40, U-238, and Th-232 [3,16,17,22,31,32]. In the diagram (Figure 4), the values of specific activity of natural radionuclides in cryoconites of glaciers of different regions and our obtained data are presented. It is revealed that the activity of radionuclide U-238 in cryoconites of the glaciers we studied is comparable to data from Arctic glaciers [16], slightly lower than on Mount Elbrus [22] and Transcaucasia [31], and significantly lower than on Alpine glaciers [17]. Another natural radionuclide, Th-232, has significantly lower activity values on the glaciers of the Central Caucasus (Tsey, Skazka, and Bezengi) that we studied compared to cryoconites from glaciers in other regions of the Earth. As for the natural radionuclide K-40, its activity is comparable to the data obtained on the glaciers of Mount Elbrus but significantly lower than in the Alps and Antarctica [32]. From the presented diagram (Figure 4), we can also see that the scatter of specific activity values of the studied natural radionuclides on the glaciers we investigated is lower than that on glaciers from other regions. This is probably due to the small number of samples in our study and the fact that we took samples only from the surface of glaciers, while other studies took samples from cryoconite holes.

3.2. Specific Activity of Anthropogenic Radionuclide Cs-137 in Cryoconites

In addition to natural radionuclides, a 661.7 keV line from decays of anthropogenic isotope Cs-137 was detected on the spectra, half-life—30.08 years, Eγ—661.7 keV, quanta yield per decay—85.1%. The obtained data (Table 3) show that the coefficient of variation of anthropogenic radionuclide Cs-137 on the studied glaciers shows an average level, within each glacier. As for the coefficient of variation of Cs-137 in cryoconites of different glaciers studied by us, it has high variability and amounts to 56%. Researchers [17,33] explained the high variability of radionuclides on glaciers by differences in supraglacial hydrology, which strongly affects the accumulation of radionuclides in cryoconite, and by different macroscopic features of individual cryoconite deposits.
A comparison of the average values of Cs-137 activity in cryoconites of the glaciers studied by us showed (see Table 3) that it is higher on the Skazka glacier than on Tsey, although the differences are not statistically significant. Probably, the higher values of this radionuclide are due to the fact that the Skazka Gorge is located in an area more exposed to anthropogenic impact, since, unlike the Tsey Gorge, it is not located in a protected area. In the work [22], it was pointed out that cryoconites of the Garabashi glacier located on Mt. Elbrus, which is highly exposed to anthropogenic load, contain more radionuclide Cs-137 than glaciers (Maly Azau and Terskol) of Mt. Elbrus less affected by human activity. The specific activity of Cs-137 in cryoconites of the Bezengi glacier compared to the Tsey and Skazka glaciers is statistically significantly (t > 7.8, p < 0.002) lower by 4.7 and 5.2 times, respectively.
Since the radionuclide Cs-137 is one of the most, if not the most, frequently studied radionuclides in environmental studies worldwide, we compared the data obtained from the glaciers of the Central Caucasus (Tsey, Skazka, and Bezengi) with previously published data for other regions of the Earth. The diagram (Figure 5) presents data on the specific activity of radionuclide Cs-137 in cryoconites from glaciers of different regions. A comparison of the data shows that the glaciers of the Central Caucasus, studied by us, have low values of specific activity of radionuclide Cs-137 and averaged from 0.51 Bq/kg (Bezengi) to 2.61 Bq/kg (Skazka). Similarly low and comparable values of activity of this radionuclide were found only in cryoconites of glaciers on Mount Elbrus [22] and in Antarctica [32], although in these regions, the activity of Cs-137 was slightly higher and averaged 14.3 Bq/kg and 10.9 Bq/kg, respectively. In contrast, according to the previously published data [16,17,31], very high concentrations of the anthropogenic radionuclide Cs-137 were found in cryoconites from glaciers in the Arctic (3–1095 Bq/kg), Transcaucasia (580–4900 Bq/kg), and in the Alps (325–13558 Bq/kg). The scatter of data on the activity of radionuclide Cs-137, as well as on natural radionuclides, is smaller than on other glaciers, except for the glaciers of Mount Elbrus [22] and Antarctica [32], where low variation in radionuclide activity was detected. This small variation is probably due to both the small number of samples used in these studies and the low activity of radionuclide Cs-137 on these glaciers. Low activity values of radionuclide Cs-137 in our studied cryoconites from glaciers of the Central Caucasus are obtained due to the fact that, being soluble and mobile in aqueous medium, this radionuclide is prone to movement and leaching figure [34], and since in our study, samples were taken in the lower part of glaciers, where glacier melting is more intense, Cs-137 was washed out together with meltwater and rainfall. But this is just an assumption, which should be verified in further studies by examining samples of cryoconites collected in the upper parts of the glaciers. In addition, the low activity of anthropogenic radionuclide can be explained by the fact that our research took place 37 years after the Chernobyl accident, which was the main source of this radionuclide, and as mentioned above, the half-life of Cs-137 is 30 years.

4. Conclusions

The data on specific activity of natural (K-40, U-238, U-235, and Th-232) and anthropogenic radionuclide (Cs-137) in cryoconites of glaciers of the Central Caucasus (Tsey, Skazka, and Bezengi) are presented. It was shown that the studied natural radionuclides, both within one glacier and between all studied glaciers, have weak and average variability, except for radionuclide K-40, which showed a high degree of variation coefficient (40%). The anthropogenic radionuclide Cs-137 within one glacier also has medium variability, while between all studied glaciers, a high level of variation coefficient was found (56%). The average mean values of specific activity of the studied natural radionuclides on the glaciers we investigated showed that, despite some differences, they are not significant, and statistically significant (t > 7.4, p < 0.002) changes were found only for the natural radionuclide K-40. As for the anthropogenic radionuclide Cs-137, the comparison of the average indices showed that no significant differences in its activity were found between the Tsey and Skazka glaciers, while in the cryoconites of the Bezengi glacier, which is located at a greater territorial distance from these two glaciers, the concentration of radiocaesium is statistically significantly (t > 7.8, p < 0.002) lower. A comparison of our results with literature data showed that natural radionuclides (K-40, U-238, and Th-232) in cryoconites of glaciers of the Central Caucasus are similar to their concentrations in glaciers of the Caucasus (Mount Elbrus), Transcaucasia (Georgia), and the Arctic (Spitsbergen) and significantly lower than in Antarctica and the Alps. The low values of specific activity of anthropogenic radionuclide Cs-137 obtained by us are comparable with the data obtained on glaciers of Mount Elbrus and Antarctica and are much (sometimes several thousand times) lower than in the Alps, the Arctic, and Georgia. The results obtained in this work have shown that, currently, the specific activity of the studied radionuclides in the cryoconites of the glaciers of the Central Caucasus is not high, and there is no essential risk to human health. However, it is important to continue monitoring the radioactivity of glacial cryoconites and compare them with the data obtained in this study in order to identify negative changes. Thus, we continued our work on the study of radionuclide activity in cryoconites of the Caucasus glaciers, but further studies are needed to complete the data on the distribution of natural and anthropogenic radionuclides in cryoconites of mountain glaciers.

Author Contributions

E.A.: project conceptualization, proofreading of the manuscript, and obtaining funding; R.T.: sampling and writing the manuscript; A.G. (Albert Gangapshev): analytical work and proofreading of the manuscript; A.G. (Ali Gezhaev): analytical work. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the grant Russian Science Foundation “Comparative metagenomic study of the carbon cycle microbiome in permafrost regions of the Yamal Peninsula and the Qinghai-Tibet Plateau No. 24-44-00006”.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Original material presented in this study can be forwarded to the corresponding author if requested.

Acknowledgments

The authors are grateful to the staff of the St. Petersburg State University, Kushnov I.D., Federal State Budgetary Institution “Reserved Ossetia-Alania” Popov K.P., North Ossetian State University, Cherchesova S.K., for assistance during field work.

Conflicts of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Figure 1. Research areas: (A) Bezengi glacier (Kabardino-Balkarian Republic) and (B) Tsey and Skazka glaciers (Republic of North Ossetia).
Figure 1. Research areas: (A) Bezengi glacier (Kabardino-Balkarian Republic) and (B) Tsey and Skazka glaciers (Republic of North Ossetia).
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Figure 2. Explored valley glaciers of the Central Caucasus: (A) Tsey, (B) Skazka, and (C) Bezengi.
Figure 2. Explored valley glaciers of the Central Caucasus: (A) Tsey, (B) Skazka, and (C) Bezengi.
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Figure 3. Spectra of sample Tsey-3 collected over 100 h and the background spectrum of the HPGe detector collected over 1008 h, normalized to 100 h.
Figure 3. Spectra of sample Tsey-3 collected over 100 h and the background spectrum of the HPGe detector collected over 1008 h, normalized to 100 h.
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Figure 4. Specific activity of natural radionuclides U-238, Th-232, and K-40 (Bq/kg) in cryoconites of glaciers in various regions of the Earth: 1—Tsey, 2—Skazka, and 3—Bezengi, Central Caucasus (our research); 4—Mount Elbrus, Caucasus, Russia [22]; 5—Alps [17]; 6—Arctic [16]; 7—Mount Adishi, Transcaucasia, Georgia [31]; 8—Antarctica [32].
Figure 4. Specific activity of natural radionuclides U-238, Th-232, and K-40 (Bq/kg) in cryoconites of glaciers in various regions of the Earth: 1—Tsey, 2—Skazka, and 3—Bezengi, Central Caucasus (our research); 4—Mount Elbrus, Caucasus, Russia [22]; 5—Alps [17]; 6—Arctic [16]; 7—Mount Adishi, Transcaucasia, Georgia [31]; 8—Antarctica [32].
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Figure 5. Specific activity of anthropogenic radionuclide Cs-137 (Bq/kg) in cryoconites of glaciers in various regions of the Earth: 1—Tsey, 2—Skazka, and 3—Bezengi, Central Caucasus (our research); 4—Mount Elbrus, Caucasus, Russia [22]; 5—Alps [17]; 6—Arctic [16]; 7—Mount Adishi, Transcaucasia, Georgia [31]; 8—Antarctica [32].
Figure 5. Specific activity of anthropogenic radionuclide Cs-137 (Bq/kg) in cryoconites of glaciers in various regions of the Earth: 1—Tsey, 2—Skazka, and 3—Bezengi, Central Caucasus (our research); 4—Mount Elbrus, Caucasus, Russia [22]; 5—Alps [17]; 6—Arctic [16]; 7—Mount Adishi, Transcaucasia, Georgia [31]; 8—Antarctica [32].
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Table 1. Characteristics of sampling sites.
Table 1. Characteristics of sampling sites.
Sampling LocationMaterialAltitude, m. aslCoordinates
Tsey GlacierCryoconite from the glacier surface2275N 42.774444°
E 43.861389°
Skazka GlacierCryoconite from the glacier surface2432N 42.767500°
E 43.893889°
Bezengi GlacierCryoconite from the glacier surface2340N 43.101834°
E 43.125858°
Table 2. Statistical indices of determined natural radionuclides in cryoconites of the studied glaciers.
Table 2. Statistical indices of determined natural radionuclides in cryoconites of the studied glaciers.
RadionuclidesNumber of SamplesMean, Bq/kgMinimum, Bq/kgMaximum, Bq/kgCoef. Var., %Standard Error of Mean, Bq/kg
Tsey Glacier
K-4031831821861.31.3
U-23531.51.21.717.20.2
U-238319.817.521.610.61.2
Th-232321.320.421.93.70.5
Skazka Glacier
K-4033483273808.116.3
U-23531.41.31.716.10.1
U-238320.420.120.61.30.2
Th-232328.126.929.85.30.9
Bezengi Glacier
K-403501.74875274.412.7
U-23531.71.61.98.80.1
U-238325.720.931.119.93.0
Th-232325.121.227.213.52.0
Table 3. Statistical indicators of anthropogenic radionuclide Cs-137 in cryoconites of the studied glaciers.
Table 3. Statistical indicators of anthropogenic radionuclide Cs-137 in cryoconites of the studied glaciers.
RadionuclidesNumber of SamplesMean, Bq/kgMinimum, Bq/kgMaximum, Bq/kgCoef. Var., %Standard Error of Mean, Bq/kg
Tsey Glacier
Cs-13732.42.12.9170.2
Skazka Glacier
Cs-13732.62.22.812.30.2
Bezengi Glacier
Cs-13730.50.40.619.80.1
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Tembotov, R.; Gangapshev, A.; Gezhaev, A.; Abakumov, E. Specific Activity of Radionuclides in Cryoconite Sediments of Glaciers of the Central Caucasus (Tsey, Skazka, Bezengi), Russia. Earth 2025, 6, 60. https://doi.org/10.3390/earth6020060

AMA Style

Tembotov R, Gangapshev A, Gezhaev A, Abakumov E. Specific Activity of Radionuclides in Cryoconite Sediments of Glaciers of the Central Caucasus (Tsey, Skazka, Bezengi), Russia. Earth. 2025; 6(2):60. https://doi.org/10.3390/earth6020060

Chicago/Turabian Style

Tembotov, Rustam, Albert Gangapshev, Ali Gezhaev, and Evgeny Abakumov. 2025. "Specific Activity of Radionuclides in Cryoconite Sediments of Glaciers of the Central Caucasus (Tsey, Skazka, Bezengi), Russia" Earth 6, no. 2: 60. https://doi.org/10.3390/earth6020060

APA Style

Tembotov, R., Gangapshev, A., Gezhaev, A., & Abakumov, E. (2025). Specific Activity of Radionuclides in Cryoconite Sediments of Glaciers of the Central Caucasus (Tsey, Skazka, Bezengi), Russia. Earth, 6(2), 60. https://doi.org/10.3390/earth6020060

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