Abstract: ⁷Be is an important cosmogenic radionuclide and natural radioactive tracer. It holds unique value in studies of atmospheric transport, particle deposition, and radiation environment assessment. Currently, comprehensive comparative studies on atmospheric ⁷Be in southeastern coastal cities and surrounding counties of China remain scarce.Based on aerosol sampling from 2021 to 2023 in Fuzhou urban area and Lianjiang County, the average activity concentrations of ⁷Be were 3.95 mBq/m³ and 3.92 mBq/m³, respectively. This indicates good regional consistency. Both sites showed a clear seasonal pattern, with higher values in spring and lower in summer. Specifically, the spring concentrations were 3.88 times (Fuzhou) and 2.73 times (Lianjiang) those in summer. The primary reason is increased downward transport of stratospheric air into the troposphere in spring (Springtime stratospheric intrusion), bringing high-level ⁷Be to the surface. This process, together with summer precipitation scavenging, co-controls the observed seasonal characteristics.These findings provide baseline data for tracing regional atmospheric processes and assessing the radiation environment. Future work can combine meteorological factors to further elucidate the transport mechanisms.

Key words: Aerosol, ⁷Be, Activity concentration, Absorbed dose, Fuzhou City