Daily-weekly scale precipitation events in the monsoon marginal zone recorded by high-resolution δ18O of land snail shells

Weather-scale precipitation have a significant impact on ecosystems and human activities. Reconstructing weather-scale precipitation events is critical to improving our understanding of precipitation event mechanisms. Currently, the snail shells ultra-high resolution δ¹⁸O records obtained by secondary ion mass spectroscopy (SIMS) is the main methods of reconstruction the terrestrial weather-scale precipitation events. However, research in this field is limited due to the rarity and costliness of SIMS instrumentation, as well as the complexity of sample preparation. In this study, we collected three modern land snails (Cathaica fasciola) from the Shizuishan area in Northwest China in June, September, and December 2021. The shells of these snails were sampled continuously with a spatial resolution of ~700μm and tested using gas-source mass spectrometry (GSMS) to obtain high-resolution δ¹⁸O records. The results showed that the δ¹⁸O of snails shell (δ¹⁸O_shell) of different snails grown at the same time period were well reproducible. We obtained the growth rate of Cathaica fasciola is 546μm/day from June to September. This growth rate is obviously faster than Xingyang (181μm/day from June to September) and Xi'an (56μm/day from April to September). The observed disparity in growth rates may be attributed to the snail survival strategy changes, which appear to be more efficient in water usage in the monsoon margin zone. More importantly, the δ¹⁸O_shell exhibited sensitivity to precipitation, as evidenced by three negative fluctuations in δ¹⁸O_shell record that corresponded to three precipitation events during the period. These findings indicate that δ¹⁸O_shell records obtained by GSMS could effectively capture weather-scale precipitation information in the monsoon margin region. GSMS is widely used, less costly for testing, and relatively simple for sample preparation. This greatly improves the feasibility and applicability in reconstruct weather-scale precipitation events under different climatic conditions using δ¹⁸O_shell record, and deepens our understanding of the mechanisms such events. Meanwhile, this finding holds significance in unraveling the intricate nature of weather-scale precipitation events.