Cosmogenic radionuclide Beryllium-7 and Beryllium-10 characteristics and influencing factors in different natural climate regions, China.

Abstract

The cosmogenic radionuclide ⁷Be (T_1/2: 53.29 days) and ¹⁰Be (T_1/2: 1.39 My), as unique tracers, play an excellent indicative role in atmospheric environmental changes and Earth surface processes. Currently, their different characteristics and influencing factors in various natural climate environments are still vague. Here, we used a state-of-the-art accelerator mass spectrometry to synchronously measure the ultra-trace ⁷Be and ¹⁰Be in aerosols, obtaining the spatial and temporal variability of daily-resolution atmospheric ⁷Be and ¹⁰Be in different natural climate regions (n = 11) of China. The survey results show that the ¹⁰Be and ⁷Be concentrations in the central/southern regions of China (22-38°N, 85-119°E) in 2020/21 are (0.5-18.7)·10⁴ and (0.4-6.1)·10⁴ atoms·m^-3, respectively, with ¹⁰Be/⁷Be ratios of 0.7-3.3. Except for the Tibetan Plateau, there are differences in the concentration thresholds of ¹⁰Be and ⁷Be in various regions, especially in ¹⁰Be concentration. These ¹⁰Be/⁷Be thresholds are consistent in areas with an altitude range of 4-3420 m a.s.l and reach their highest values throughout the spring of the year. The analysis results indicate that both ⁷Be and ¹⁰Be are influenced by local meteorological conditions such as rainfall and boundary layer disturbances, while also exhibiting different distribution states. This distribution states is due to the re-suspended soil dust ¹⁰Be interference caused by soil wind erosion to varying degrees in different regions, with an average contribution to aerosol ¹⁰Be of 5.0 ± 2.6 %-24.2 % ± 13.3 %, and is controlled by local annual rainfall (r = 0.8, p < 0.01). Furthermore, unlike the characteristics of ¹⁰Be and ⁷Be concentrations influenced by local meteorological conditions, the daily variation of corrected ¹⁰Be/⁷Be exhibits independence from meteorological processes other than stratosphere troposphere transport, and its significant seasonal oscillations indicate changes in atmospheric circulation in the East Asian monsoon region.