Wet deposition of ⁷Be and ¹⁰Be in Xi’an, China: Variation characteristics and influencing factors

Abstract Cosmogenic 7 Be and 10 Be are effective tracers for studying atmospheric dynamics and Earth’s surface processes, with over 90% of these isotopes reaching the surface via wet deposition. However, the characteristics and influencing factors of 7 Be and 10 Be wet deposition remain unclear in different regions, limiting the precision of these nuclides as tracers of environmental change. This study analyzes the annual variation of 7 Be and 10 Be wet deposition in Xi’an and examines the impact of precipitation on their deposition. Ultra-trace levels of 7 Be and 10 Be in precipitation were synchronously measured using state-of-the-art accelerator mass spectrometry. One-year (July 30, 2020 to September 3, 2021), high-frequency (individual rain events) and time-synchronized series of observations of 7 Be and 10 Be wet deposition data (n = 49) were analyzed. The total annual wet deposition fluxes of 7 Be and 10 Be in central China (34.22°N, 109.01°E) for 2020/21 were (218 ± 24) × 10 8 atoms·m –2 ·yr –1 and (314 ± 16) × 10 8 atoms·m –2 ·yr –1 , respectively. Precipitation amount, intensity, and duration were quantitatively analyzed for their effects on total wet deposition flux, mean concentration, washout ratio, deposition velocity, and scavenging coefficient of 7 Be and 10 Be during individual rain events. The results indicate that precipitation amount is the most significant factor influencing the wet deposition flux of both nuclides.