DOI: 10.57760/sciencedb.hjs.00144
title: Spatiotemporal characteristics and mechanisms of 7Be and 210Pb in the atmosphere
title: 大气中7Be和210Pb时空分布特征差异和机制解析

description: [Background]: 7Be and 210Pb are the main radionuclides for monitoring the quality of the radiation environment of atmospheric aerosols, and the internal irradiation caused by their adsorption into aerosols and entry into the human body will be harmful to the human body, so it is of great significance to explore the characteristics and mechanisms of their spatial and temporal distribution and dose contribution. [Purpose]: The aim of this study is to investigate the differences in the spatial and temporal distributions of atmospheric 7Be and 210Pb and the mechanisms of these differences.  [Methods]: In this paper, 75 aerosol samples were collected from Nanning City, Guangxi, from January 2015 to December 2017 and from January 2019 to May 2022 using an ultra-high-flow air aerosol sampler, and the activity concentrations of 7Be and 210Pb in the aerosol were measured and analyzed using a high-purity germanium γ-spectrometer. We systematically collected the activity concentration data of 7Be and 210Pb in 17 areas of the country, as well as PM2.5, PM10 and O3 air concentration data from January 2014 to November 2023 in Nanning. The HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory Model) model was used for the atmospheric traceability model. [Results]: The activity concentrations of 7Be in 41 aerosol samples from January 2019 to May 2022 ranges from 0.27 to 11.95 mBq/m3, with a mean value of 3.68±0.51 mBq/m3; the activity concentrations of 210Pb in 60 aerosol samples from January 2015 to December 2017 and from January 2019 to February 2021 ranges from 0.23 to 4.33 mBq/m3, with a mean value of 1.51±0.13 mBq/m3. Combining the 7Be and 210Pb activity concentration data in 17 areas of China, the seasonal distribution of 7Be and 210Pb activity concentrations in the atmosphere of China is characterized by an overall high in winter and spring, and a low in summer and autumn, but 7Be reaches its maximum value in spring while 210Pb in winter. The correlation analysis shows that 7Be has a significant positive correlation with PM2.5, PM10, O3, and has the best correlation with PM10. 210Pb has a significant positive correlation with PM2.5 and PM10 and has the best correlation with PM2.5, while it is not correlated with O3. The traceability analysis of air masses in Nanning City of the 2021 shows that the summer air masses mainly come from the oceanic air masses in the south with lower particle concentration, and the winter air masses mainly come from the continental air masses in the north with higher particle concentration. Combining the 7Be and 210Pb activity concentration data in 17 areas of China, there are effects in the spatial distribution of 7Be and 210Pb activity concentrations. The latitudinal effects: the mean 210Pb activity concentration in the area north of about 40°N (3.20±0.24 mBq/m3) is about 2.2 times higher than that in the area south of about 40°N (1.48±0.06 mBq/m3); the mean value of 7Be activity concentration in the area north of about 35°N (7.44±0.26 mBq/m3) is about 1.9 times of that in the area south of about 35°N (3.92±0.19 mBq/m3). The altitudinal effect: the 7Be activity concentration is greater at high altitude than at low altitude. Based on the average of winter-spring and summer-autumn activity concentrations of 7Be and 210Pb in 17 regions of the country, it can be estimated that the radiation dose due to 7Be and 210Pb in winter-spring (42.08 μSv/a) is about 1.4 times higher than that in summer-autumn (31.00 μSv/a). Integration of monitoring data on activity concentrations of 7Be and 210Pb in 17 regions of the country reveals that the annual effective dose due to 7Be and 210Pb in the area north of 40°N (65.48 μSv/a) is about 2.0 times higher than that in the area south of 35°N (32.75 μSv/a). The mean annual pending effective doses due to 7Be and 210Pb are 2.47×10-3 μSv/a and 33.57 μSv/a, respectively.  [Conclusions]: 7Be and 210Pb are adsorbed on the particulate matter and transported in the atmosphere, and the PM2.5 and PM10 concentrations are low in summer and autumn while high in winter and spring due to the monsoon regulation, so the 7Be and 210Pb show the seasonal distribution characteristics of low in summer and autumn and high in winter and spring. The highest 7Be activity concentration in spring is related to the "spring leakage", while the highest 210Pb activity concentration in winter is mainly influenced by the Eurasian land-based air masses in the north. The latitudinal effect of 210Pb is probably related to the large amount of particulate matter brought by the northwest land-source winds in winter and the combustion process in winter heating system. The latitudinal effect of 7Be may be attributed to the “spring leakage” of 7Be that occurs in mid-latitudes in the spring. The altitudinal effect of 7Be is controlled by the top-down transport of 7Be from the stratosphere to the troposphere. 
description: [Background]: 7Be and 210Pb are the main radionuclides for monitoring the quality of the radiation environment of atmospheric aerosols, and the internal irradiation caused by their adsorption into aerosols and entry into the human body will be harmful to the human body, so it is of great significance to explore the characteristics and mechanisms of their spatial and temporal distribution and dose contribution. [Purpose]: The aim of this study is to investigate the differences in the spatial and temporal distributions of atmospheric 7Be and 210Pb and the mechanisms of these differences.  [Methods]: In this paper, 75 aerosol samples were collected from Nanning City, Guangxi, from January 2015 to December 2017 and from January 2019 to May 2022 using an ultra-high-flow air aerosol sampler, and the activity concentrations of 7Be and 210Pb in the aerosol were measured and analyzed using a high-purity germanium γ-spectrometer. We systematically collected the activity concentration data of 7Be and 210Pb in 17 areas of the country, as well as PM2.5, PM10 and O3 air concentration data from January 2014 to November 2023 in Nanning. The HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory Model) model was used for the atmospheric traceability model. [Results]: The activity concentrations of 7Be in 41 aerosol samples from January 2019 to May 2022 ranges from 0.27 to 11.95 mBq/m3, with a mean value of 3.68±0.51 mBq/m3; the activity concentrations of 210Pb in 60 aerosol samples from January 2015 to December 2017 and from January 2019 to February 2021 ranges from 0.23 to 4.33 mBq/m3, with a mean value of 1.51±0.13 mBq/m3. Combining the 7Be and 210Pb activity concentration data in 17 areas of China, the seasonal distribution of 7Be and 210Pb activity concentrations in the atmosphere of China is characterized by an overall high in winter and spring, and a low in summer and autumn, but 7Be reaches its maximum value in spring while 210Pb in winter. The correlation analysis shows that 7Be has a significant positive correlation with PM2.5, PM10, O3, and has the best correlation with PM10. 210Pb has a significant positive correlation with PM2.5 and PM10 and has the best correlation with PM2.5, while it is not correlated with O3. The traceability analysis of air masses in Nanning City of the 2021 shows that the summer air masses mainly come from the oceanic air masses in the south with lower particle concentration, and the winter air masses mainly come from the continental air masses in the north with higher particle concentration. Combining the 7Be and 210Pb activity concentration data in 17 areas of China, there are effects in the spatial distribution of 7Be and 210Pb activity concentrations. The latitudinal effects: the mean 210Pb activity concentration in the area north of about 40°N (3.20±0.24 mBq/m3) is about 2.2 times higher than that in the area south of about 40°N (1.48±0.06 mBq/m3); the mean value of 7Be activity concentration in the area north of about 35°N (7.44±0.26 mBq/m3) is about 1.9 times of that in the area south of about 35°N (3.92±0.19 mBq/m3). The altitudinal effect: the 7Be activity concentration is greater at high altitude than at low altitude. Based on the average of winter-spring and summer-autumn activity concentrations of 7Be and 210Pb in 17 regions of the country, it can be estimated that the radiation dose due to 7Be and 210Pb in winter-spring (42.08 μSv/a) is about 1.4 times higher than that in summer-autumn (31.00 μSv/a). Integration of monitoring data on activity concentrations of 7Be and 210Pb in 17 regions of the country reveals that the annual effective dose due to 7Be and 210Pb in the area north of 40°N (65.48 μSv/a) is about 2.0 times higher than that in the area south of 35°N (32.75 μSv/a). The mean annual pending effective doses due to 7Be and 210Pb are 2.47×10-3 μSv/a and 33.57 μSv/a, respectively.  [Conclusions]: 7Be and 210Pb are adsorbed on the particulate matter and transported in the atmosphere, and the PM2.5 and PM10 concentrations are low in summer and autumn while high in winter and spring due to the monsoon regulation, so the 7Be and 210Pb show the seasonal distribution characteristics of low in summer and autumn and high in winter and spring. The highest 7Be activity concentration in spring is related to the "spring leakage", while the highest 210Pb activity concentration in winter is mainly influenced by the Eurasian land-based air masses in the north. The latitudinal effect of 210Pb is probably related to the large amount of particulate matter brought by the northwest land-source winds in winter and the combustion process in winter heating system. The latitudinal effect of 7Be may be attributed to the “spring leakage” of 7Be that occurs in mid-latitudes in the spring. The altitudinal effect of 7Be is controlled by the top-down transport of 7Be from the stratosphere to the troposphere.