Correlation Analysis of Atmospheric Be-7 Concentrations and Environmental Factors in the Republic of Korea

Jeong Woo Lee; Geon Woo Son; Chang Hee Han; Shin Dong Lee; Kwang Pyo Kim

doi:10.14407/jrpr.2024.00367

J. Radiat. Prot. Res > Volume 50(3); 2025 > Article

Lee, Son, Han, Lee, and Kim: Correlation Analysis of Atmospheric Be-7 Concentrations and Environmental Factors in the Republic of Korea

Technical Note

J. Radiat. Prot. Res 2025; 50(3): 193-202.

Published online: September 23, 2025

DOI: https://doi.org/10.14407/jrpr.2024.00367

Correlation Analysis of Atmospheric Be-7 Concentrations and Environmental Factors in the Republic of Korea

Department of Nuclear Engineering, Kyung Hee University, Seoul, Republic of Korea

Corresponding author: Kwang Pyo Kim, Department of Nuclear Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin 17104, Republic of Korea E-mail: kpkim@khu.ac.kr, https://orcid.org/0000-0003-0544-2978

Received November 20, 2024 Revised February 3, 2025 Accepted March 24, 2025

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background:

Beryllium-7 (Be-7), influenced by various environmental factors, is valuable for tracking radioactive material migration due to its short half-life and dynamic atmospheric distribution. These properties make Be-7 particularly useful for assessing the behavior of radioactive substances under changing environmental conditions or after radiation incidents. This study aims to establish foundational data by examining the correlation between Be-7 concentrations and environmental factors specific to the Republic of Korea.

Materials and Methods:

Be-7 radiation concentrations from 2013 to 2022 were collected from the National Environmental Radiation Survey Report of the Korea Institute of Nuclear Safety. Precipitation, humidity, particulate matter (PM₁₀), and atmospheric pressure data were sourced from the Korea Meteorological Administration and the Ministry of Environment. Monthly and seasonal trends were analyzed, and Pearson correlation coefficients were used to assess the relationship between Be-7 concentrations and environmental factors, with the significance evaluated using p-values.

Results and Discussion:

Analysis showed consistent nationwide trends, with Be-7 concentrations significantly decreasing each summer. Precipitation and humidity peaked in summer and negatively correlated with Be-7 concentrations, whereas PM₁₀ and atmospheric pressure were lowest in summer and positively correlated with Be-7 concentrations. All correlations had p-values below 0.001, indicating statistical significance.

Conclusion:

The findings indicate a significant relationship between Be-7 concentrations and environmental factors in the Republic of Korea, offering essential data for future research on radioactive material migration and informing environmental radiation safety strategies.

Keywords: Beryllium-7, Radioactivity Concentration, Atmosphere, Environmental Factors, Correlation Analysis

Introduction

The International Atomic Energy Agency uses radioisotopes to monitor the pathways of anthropogenic radionuclides in the environment, predict their distribution, and estimate their impacts on ecosystems [1]. Among these radioisotopes, Beryllium-7 (Be-7), a radioisotope with cosmic origin, is formed in the atmosphere, attached to aerosol particles, and deposited on the Earth’s surface through wet and dry processes [2]. Owing to its characteristics, Be-7 plays a crucial role in tracking the migration of radioactive materials in the atmosphere and serves as a useful indicator for studying the migration pathways and deposition processes of these materials [3]. In particular, the short half-life and changes in the distribution of Be-7 in the atmosphere enable the real-time analysis of material migration, facilitating a precise understanding of the behavior of radioactive materials under environmental changes, radiation accidents, and nuclear tests [4,5]. Therefore, to accurately predict the migration pathways of radioactive materials, the correlation between Be-7 concentrations and environmental factors specific to the Republic of Korea’s domestic conditions must be analyzed.

Researcher at the National Atomic Energy Commission of Argentina has analyzed the atmospheric radiation concentration of Be-7 and studied its relationships with other environmental variables using the Pearson correlation coefficient [6]. Researchers at Hanyang University analyzed the K-40 and Be-7 concentrations in precipitation and fallout samples collected in the Republic of Korea, identified their seasonal variability, and examined their correlation with environmental factors, such as rainfall and particulate matter (PM) [7]. Researchers at the European Commission Joint Research Center evaluated the meteorological conditions and Be-7 concentrations in Spain to evaluate their seasonal variations and impact on air quality [8]. A team from the Nuclear Science Research Institute of Japan’s Atomic Energy Agency studied the distribution and behavior of Be-7 in the atmosphere of Saudi Arabia using a medium-capacity air sampler and high-purity germanium (HPGe) detector [9]. Researchers at the Malaysian Nuclear Agency evaluated the correlation between the atmospheric radiation concentration of Be-7 and meteorological parameters during the northeast monsoon in Tanah Rata in the Cameron Highlands, analyzing the effects on the dispersion and deposition of radioactive nuclides [10]. Investigators from Lodz University of Technology analyzed the relationship between Be-7, Pb-210, and Po-210 concentrations and meteorological conditions through a predictive analytical approach based on factor regression methods [11].

The atmospheric radiation concentration of Be-7 is influenced by various environmental factors, including meteorological conditions, air pollution levels, and seasonal variations. Although many international studies have analyzed the correlation between Be-7 concentrations and environmental factors, differences in the Republic of Korea’s atmospheric conditions compared with those in other countries may lead to distinct correlation results. In the Republic of Korea, Be-7 concentrations in precipitation and fallout have been analyzed to investigate their correlation with environmental factors. However, tracking the migration of pollutants and radioactive materials in the atmosphere is challenging, as Be-7 is formed in the atmosphere and attached to aerosol particles before deposition. Accordingly, to predict the migration of radioactive substances in the atmosphere, a correlation analysis must be conducted by considering data on Be-7 concentrations and environmental factors in the Republic of Korea.

In this study, an analysis was conducted to examine the correlation between the radioactive concentration of Be-7 in the atmosphere and environmental factors. Accordingly, the radioactive concentration of Be-7 in the atmosphere for the past 10 years was analyzed to identify monthly trends. Additionally, environmental factors influencing the migration and deposition of atmospheric particles were selected, and data for the same period were analyzed. Finally, a correlation analysis was conducted using the data on the Be-7 concentration in the atmosphere and environmental factors, and the significance of the derived correlation coefficients was evaluated.

Materials and Methods

1. Analysis of Be-7 Radiation Concentration

Fig. 1 shows a summary of the regions selected for analyzing the radioactive concentrations of Be-7 in the Republic of Korea for this study [12–21]. In these regions, regional radioactivity monitoring stations are operated to monitor environmental radiation across the country, conducting analyses in numerous cities, such as Seoul, Chuncheon, Daejeon, Gunsan, Gwangju, Daegu, Busan, Jeju, Gangneung, Andong, Suwon, Cheongju, Ulsan, Incheon, and Jinju. The 15 regional radioactivity monitoring stations submit annual Environmental Radioactivity Survey in Korea reports to the Korea Institute of Nuclear Safety (KINS), which include detailed analyses of radioactive concentrations in airborne particulates, precipitation, and other environmental factors by region.

According to the Environmental Radioactivity Survey in Korea, high volume air sampler is used at regional radioactivity monitoring stations nationwide to analyze the concentrations of airborne radioactive nuclides. Filter papers (Whatman filter paper No. 41) are used for sample collection. The samplers are installed at a height of 1 m above the ground within a Stevenson screen, and filter papers are continuously used to collect airborne particulate samples through the air intake of the samplers. The filter papers are replaced approximately every 48 hours, considering the saturation level of the collected particulates. The filter papers collected over a month are placed in crucibles and ashed in an electric furnace at 450 °C. The furnace temperature is maintained below 450 °C, and the ashing process is conducted for more than 24 hours. After ashing, the samples are transferred to cylindrical containers (KINS-D6H4) and sealed using parafilm. The sealed samples are measured for 80,000 seconds using a HPGe detector that has been efficiency-calibrated. The Genie2K program was used to apply the geometry efficiency of the samples, and the concentrations of radioactive nuclides were analyzed after performing nuclide identification for Be-7. Additionally, KINS conducts annual radioactivity analysis proficiency evaluations for regional radioactivity monitoring stations to maintain the reliability of environmental radioactivity analysis data and manage the quality of analysis techniques [12–21].

In this study, the Environmental Radioactivity Survey in Korea reports published from 2013 to 2022 were utilized to analyze the radiation concentration of Be-7 in the atmosphere in the Republic of Korea over the past decade. Seasonal periods were defined based on the Republic of Korea’s seasonal cycle: March to May as spring, June to August as summer, September to November as autumn, and December to February as winter; these definitions were utilized in the analysis of the radioactive concentrations of Be-7.

2. Analysis of Environmental Factors

In this study, precipitation, humidity, PM₁₀ (particulate matter with an aerodynamic diameter of 10 μm or less), and atmospheric pressure were selected as environmental factors for analysis. A range of meteorological and atmospheric-related factors were considered to identify those that could influence the radioactive concentration of Be-7 in the atmosphere. Be-7 is primarily produced in the atmosphere through natural radioactive decay, and its concentration can be affected by various environmental factors [3]. Thus, the selection of environmental factors was based on their impact on the migration and deposition of atmospheric particles. In particular, particle deposition, precipitation, and humidity, which play crucial roles in cleansing the atmosphere, were identified as factors directly influencing Be-7 concentrations. PM, which can remain in aerosol form in the atmosphere for extended periods and may combine with radioactive materials, was also included as an environmental factor. Additionally, atmospheric pressure was selected owing to its direct influence on Be-7 concentrations, as it affects the migration and retention of particles in combination with aerosols.

Statistical data from the Korea Meteorological Administration and Ministry of Environment were utilized to analyze the monthly changes in the selected environmental factors, namely, precipitation, humidity, PM₁₀, and atmospheric pressure, which showed significant seasonal effects from 2013 to 2022. To minimize regional variability, environmental factor data were analyzed in 15 cities that correspond to the locations of the regional radioactivity monitoring stations. Monthly averages for each environmental factor were calculated, and the data from the past decade were examined. Variability in atmospheric pressure was analyzed using a reference value of 1,000 hPa, which serves as the standard for evaluating atmospheric stability.

3. Correlation Analysis

In this study, we analyzed the correlation between Be-7 and environmental factors using the Pearson correlation coefficient. In statistics, the Pearson correlation coefficient is a method for quantitatively evaluating the linear correlation between two variables [22]. Table 1 presents the range of coefficients used for interpreting correlations [23]. The correlation coefficient ranges from –1 to 1, where values closer to 1 and –1 indicate positive and negative linear correlations, respectively. Correlation coefficient values closer to 0 indicate weak correlation. Furthermore, the Pearson correlation coefficient facilitates a quantitative understanding of the relationship between variables, in addition to helping determine the direction and strength of the relationship. For example, a positive correlation indicates that as the concentration of Be-7 increases, a specific environmental factor also increases, whereas a negative correlation suggests the opposite. The correlations identified were categorized into positive and negative types to explain the underlying causes of the relationship between the radiation concentration of Be-7 and environmental factors. The Pearson correlation coefficient was calculated using the following Equation (1):

(1)

R=∑(Xi-X−)(Yi-Y−)∑(Xi-X−)2∑(Yi-Y−)2

In this equation, R refers to the correlation coefficient. X_i indicates the independent variable, and X− represents its mean value. Y_i denotes the dependent variable, and Y− represents the mean value of the dependent variable.

4. Correlation Evaluation

To evaluate whether the correlation between Be-7 and environmental factors is significant, the t-statistic was calculated to derive the p-value. The t-statistic is a value that helps determine if the correlation coefficient between two variables is statistically significant, rather than merely being a result of chance, and is calculated using the following Equation (2):

(2)

t=Rdf1-R2

In this equation, t represents the t-statistic, R refers to the correlation coefficient, and df denotes the degrees of freedom.

The degrees of freedom, denoted as df in Equation (2), represent the number of values that account for the two variables in the sample size (n), and are calculated as df = n–2. Degrees of freedom play a crucial role in determining the shape of the t-distribution. With an increase in sample size, the degrees of freedom also increase, thereby enhancing the reliability of the test. In this study, a total of 120 data points were used over the 10-year period, resulting in degrees of freedom calculated as follows: 120–2 =118 for a sample size of n=120.

Based on the calculated t-statistic and degrees of freedom, we derived the p-value for the correlation coefficient. The p-value measures the extremity of the t-statistic within the t-distribution and acts as the standard for determining the statistical significance of the correlation. A p-value of less than 0.001 indicates a highly significant correlation, and this criterion was applied to evaluate the significance of the correlation in this study.

Results and Discussion

1. Analysis of Be-7 Radiation Concentration

Fig. 2 shows the monthly average values of the atmospheric radiation concentration of Be-7 in the Republic of Korea over the past decade. The average, minimum, and maximum values by region showed similar trends. The seasonal analysis indicated that the radiation concentration of Be-7 decreased sharply during the summer months of July and August, followed by a gradual increase. The lowest recorded concentration was 1.26 mBq/m³ in Gwangju in July 2018, whereas the highest value was 12.6 mBq/m³ in Cheongju in October 2019. Annually, the ratio of minimum to maximum values ranged from 4.07 to 6.20. Seasonally, Be-7 concentrations ranged from 1.98–8.31 mBq/m³ in spring, 1.26–6.35 mBq/m³ in summer, 1.62–12.6 mBq/m³ in autumn, and 2.01–8.91 mBq/m 3 in winter.

2. Analysis of Environmental Factors

Fig. 3 shows the monthly average values of the selected environmental factors: precipitation, humidity, PM₁₀, and atmospheric pressure over the past decade. The analysis indicated that precipitation and humidity tended to increase during the summer months. The national average precipitation ranged from a minimum of 26.5 mm in January to a maximum of 252 mm in July, while humidity ranged from 56.7% in February to 79.1% in July. Conversely, PM₁₀ and atmospheric pressure tended to decrease during the summer. The minimum and maximum values of the national average PM₁₀ concentration were 27.6 μg/m³ and 55.1 μg/m³ in August and March, respectively, whereas atmospheric pressure showed a minimum value of 1,000 hPa in June, July, and August and a maximum value of 1,020 hPa in January and December.

3. Correlation Analysis and Evaluation

Figs. 4 and 5 show the comparison of the 10-year analysis results for Be-7 and various environmental factors. Each year, the trends in environmental factors were closely related to changes in the radiation concentration of Be-7. In particular, increases in precipitation and humidity were associated with a decrease in Be-7 concentration, whereas higher levels of PM and atmospheric pressure corresponded to an increase in the radiation concentration of Be-7.

Fig. 6 shows the correlation coefficients between the radiation concentration of Be-7 and environmental factors. According to the correlation analysis, precipitation and humidity were negatively correlated with the radiation concentration of Be-7. Specifically, the correlation coefficient between the Be-7 concentration and precipitation was –0.688, suggesting that as precipitation level increased, Be-7 concentrations decreased. Increased precipitation led to the deposition of Be-7 from the atmosphere to the ground through rainfall, causing an atmospheric cleansing effect [24]. Consequently, the higher the precipitation, the more frequently is Be-7 deposited to the ground, leading to a decrease in its concentration in the atmosphere. A correlation coefficient of –0.724 between the Be-7 concentration and humidity indicates another strong negative correlation. This trend shows that with increasing humidity, Be-7 concentrations decrease as high humidity promotes the aggregation of atmospheric particles with water vapor. These aggregated particles are more likely to settle, thereby lowering the atmospheric concentration of Be-7 [25].

Conversely, PM₁₀ and barometric pressure were found to be positively correlated with the radiation concentration of Be-7. The correlation coefficient between the radiation concentration of Be-7 and PM₁₀ was 0.452, indicating a relatively strong correlation; the radiation concentration of Be-7 tends to increase with increasing PM₁₀ concentration. PM remains suspended in the atmosphere for extended periods and can bind or attach to Be-7, resulting in a higher radiation concentration of Be-7 when PM levels are elevated [26]. The correlation coefficient between the radiation concentration of Be-7 and atmospheric pressure was 0.547, also indicating a strong correlation. This suggests that as atmospheric pressure increases, the radiation concentration of Be-7 tends to increase. During periods of high atmospheric pressure, aerosols in the atmosphere do not settle and remain airborne for longer durations, contributing to an increased radiation concentration of Be-7 [27].

Fig. 7 shows the significance levels for each environmental factor derived from the t-distribution. Initially, the t-statistic was calculated to evaluate the statistical significance of the correlations. The t-statistics, based on the degrees of freedom and correlation coefficients for each environmental factor, were –10.3, –11.4, 5.50, and 7.10 for precipitation, humidity, PM, and atmospheric pressure, respectively. Using these t-statistics, the significance levels (p-values) for the correlations between each environmental factor and the radiation concentration of Be-7 were determined. The obtained p-values were 3.67 × 10^-18, 9.33 × 10^-21, 2.24 × 10^-7, and 9.98 × 10^-11 for precipitation, humidity, PM, and atmospheric pressure, respectively. All environmental factors exhibited p-values below 0.001, indicating that the correlations between the Be-7 concentration and these factors were highly statistically significant.

Conclusion

In this study, we examined the correlation between the radiation concentration of Be-7 in the atmosphere and environmental factors. Accordingly, we conducted a monthly analysis of both the Be-7 concentrations in the atmosphere and selected environmental variables. The atmospheric Be-7 radioactivity in the Republic of Korea was evaluated using data from 15 regional radioactivity monitoring stations, as detailed in the annual Environmental Radioactivity Survey in The Republic of Korea reports submitted to the KINS. The environmental factors potentially influencing Be-7 concentration included precipitation, humidity, PM, and atmospheric pressure. Monthly data from the Korea Meteorological Administration and Ministry of Environment were used for this analysis. Finally, the correlation between the radiation concentration of Be-7 and environmental factors in the Republic of Korea was quantitatively analyzed using Pearson correlation coefficient.

The radiation concentration of Be-7 decreased sharply in the summer months of July and August and subsequently gradually increased. The minimum and maximum values of the radiation concentration of Be-7 were 1.26 mBq/m³ in Gwangju in July 2018 and 12.6 mBq/m³ in Cheongju in October 2019, respectively. The 10-year average values of precipitation and humidity showed sharp increases in summer, reaching their maximum values in July. PM concentrations decreased in summer, with a minimum value of 27.6 μg/m³, whereas atmospheric pressure exhibited a minimum value of 1,000 hPa in June, July, and August.

A comparison of data reveals that the radiation concentration of Be-7 and environmental factors exhibited consistent trends annually over the past decade. The radiation concentration of Be-7 decreased with increasing precipitation and humidity, whereas it increased with increasing PM and atmospheric pressure. The Pearson correlation coefficient was used to determine the correlation between each variable and the radiation concentration of Be-7. PM and atmospheric pressure showed relatively strong positive correlations, with correlation coefficients of 0.452 and 0.547, respectively. Precipitation and humidity exhibited strong negative correlations, with correlation coefficients of –0.688 and –0.724, respectively. The t-test, conducted to evaluate the significance of the correlation coefficients, showed t-statistics of –10.3, –11.4, 5.50, and 7.10 for precipitation, humidity, PM₁₀, and atmospheric pressure, respectively, at 118˚ of freedom. The p-values derived from the t-statistics were 3.67× 10^-18, 9.33× 10^-21, 2.24 × 10^-7, and 9.98 × 10^-11 for precipitation, humidity, PM, and atmospheric pressure, respectively. The p-values were below 0.001, indicating that the correlations between the Be-7 concentration and environmental factors were highly statistically significant.

All environmental factors showed high correlation with the Be-7 concentration, and a significance level of less than 0.01 confirms a confidence level of over 99.9%. Therefore, the environmental factors selected for this study, namely, precipitation, humidity, PM₁₀, and atmospheric pressure, were highly correlated with Be-7 in the domestic atmosphere. These results suggest that the Be-7 concentration in the Republic of Korea is significantly influenced by the environmental factors analyzed in this study. However, environmental factors that may influence Be-7 concentrations include additional variables such as wind speed, solar radiation, and atmospheric stability. Future studies need to comprehensively evaluate the factors affecting changes in atmospheric Be-7 concentrations. The results of this study, which evaluated the correlation between atmospheric Be-7 radioactivity concentrations and environmental variables, are expected to contribute to understanding the transport pathways of radioactive materials in the domestic atmospheric environment and analyzing these pathways. Furthermore, the results of this study can be utilized as a basis for future environmental monitoring and the development of strategies to address radioactive contamination.

Article Information

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Ethical Statement

This article does not contain any studies with human participants or animals performed by any of the authors.

Data Availability

Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Author Contribution

Conceptualization: Kim KP. Methodology: Kim KP. Data curation: Lee JW, Son GW, Han CH, Lee SD. Formal analysis: Kim KP. Project administration: Lee JW. Investigation: Lee JW. Visualization: Lee JW, Son GW, Han CH. Software: Lee JW, Kim KP. Validation: Kim KP. Writing - original draft: Lee JW, Kim KP. Writing - review & editing: Kim KP. Approval of final manuscript: all authors.

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Fig. 1.

Status of 15 regional radioactivity monitoring stations.

Fig. 2.

Monthly average of Be-7 radiation concentration in airborne dust across the Republic of Korea over the past 10 years.

Fig. 3.

Ten-year average of environmental factors.

Fig. 4.

Beryllium-7 (Be-7) concentrations in relation to (A) precipitation and (B) humidity, based on data from 2013 to 2022.

Fig. 5.

Beryllium-7 (Be-7) concentrations in relation to (A) particulate matter and (B) atmospheric pressure, based on data from 2013 to 2022.

Fig. 6.

Correlation coefficient between Be-7 concentration and environmental factors.

Fig. 7.

p-value by environmental factor.

Table 1.

Correlation Coefficient Ranges and Interpretations

Coefficient \|R\|	Interpretation
0.00–0.09	No or negligible
0.10–0.19	Weak
0.20–0.39	Moderate
0.40–0.59	Relatively strong
0.60–0.79	Strong
0.80–1.00	Very strong