Macroscale spatiotemporal variability of Beryllium-7 and Lead-212 in surface air driven by meteorological factors

Natural radionuclides Beryllium-7 (⁷Be) and Lead-212 (²¹²Pb) are regularly present in the atmosphere. However, study about their macroscale spatiotemporal variability and responses to meteorological drivers are limited. Therefore, using ⁷Be and ²¹²Pb measurements from 71 International Monitoring System (IMS) radionuclide stations from 2010 to 2023, this study examines the spatial (station, hemispheric) and temporal (annual, monthly, seasonal) trends of both radionuclides in surface air and their interactions with key meteorological parameters. Results showed that the global monthly average concentrations were 3.59 mBq m^-3 for ⁷Be and 46.59 mBq m^-3 for ²¹²Pb, with higher values in the Northern Hemisphere (⁷Be: 3.68 mBq m^-3, ²¹²Pb: 48.92 mBq m^-3) than in the Southern Hemisphere (⁷Be: 3.34 mBq m^-3, ²¹²Pb: 43.02 mBq m^-3). Significant station-level variability (⁷Be: 70.35 %, ²¹²Pb: 90.03 %) was observed, whereas hemispheric and temporal effects were minor. Spatially, ⁷Be formed apparent latitudinal patterns in both hemispheres. Conversely, ²¹²Pb was influenced by local meteorological conditions. Temporally, ⁷Be displayed consistent interannual and intra-annual patterns across all spatial domains, with spring-summer maxima and winter-autumn minima, whereas ²¹²Pb exhibited hemispheric-specific cycles. Correlation analysis showed that precipitation reduces, while temperature enhances, the concentrations of both radionuclides. Solar activity exerted a strong negative influence on multi-year variation of ⁷Be. Hierarchical clustering results further supported the findings from correlation analysis. Overall, this study highlights the distinct spatiotemporal trends of ⁷Be and ²¹²Pb at broader scales, thus advancing the understanding of their environmental dynamics and atmospheric radioactivity at global and hemispheric levels.