ABSTRACT
The cosmogenic radionuclide 7Be (T1/2: 53.29 days) and 10Be (T1/2: 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.
