Synoptic-scale precipitation events recorded by high-resolution intra-shell δ¹⁸O of land snail in the Asian monsoon marginal zone

Synoptic-scale precipitation events significantly impact ecosystems and human livelihoods, and it would greatly improve our understanding of their mechanisms, if the daily scale precipitation events could be reconstructed for different climatic types in the geological past. Ultra-high resolution snail shell δ¹⁸O (δ¹⁸O_shell) records obtained by secondary ion mass spectroscopy shed light on reconstructing terrestrial synoptic-scale precipitation events. However, this kind of investigation is limited due to the access and costliness of this instrumentation. In this study, we tried to reconstruct weather-scale (daily-weekly) precipitation using manually obtained intra-shell samples from living land snails (Cathaica fasciola) collected in northwest China in June, September, and December 2021. These shells were drilled continuously with a spatial resolution of ∼500–800 μm for isotope ratio mass spectrometer (IRMS) analysis of the δ¹⁸O_shell. The δ¹⁸O_shell profiles among individuals demonstrate satisfactory reproducibility, and notably, the reconstructed synoptic-scale precipitation frequency from the high-resolution intra-shell δ¹⁸O_shell is consistent with the instrumental record. This indicates that land snails δ¹⁸O_shell in the Asian monsoon marginal regions can be used to reconstruct daily-scale precipitation events through IRMS analysis. We speculate that snails adjust their growth strategies to accommodate the challenging environment in the arid and semi-arid regions by growing faster in the limited time of growing season when precipitation occurs. Altogether, this finding will promote the applications for reconstructing terrestrial paleoweather events.