中国现代表土叶腊正构烷烃氢同位素数据集（现代）

中国西北至东南55个表土样品的正构烷烃氢同位素，显示δDalk（δDn-C29、δDn-C31）与年均降水δD以及4-10月降水δD均呈显著正相关，说明正构烷烃δD记载了大气降水δD信号。但降水δD无法解释δDalk的全部变化。通过分析表观分馏值（ɛalk/p）与相对湿度、雨量、干燥指数、温度及植被类型之间的关系，结果显示表观分馏值与纬向草本/木本植物类型变化无明显关系，而与相对湿度、年均降雨量和干燥指数显著负相关，表明ɛalk/p主要受干旱影响，受植被类型的影响不大。这可能由于干旱能增强土壤水、叶水蒸发产生的氘富集，同时降低生物合成分馏造成的氘亏损。此外集成了全国表土氢同位素数据，结果显示，δDalk与大气降水δD显著正相关，表观分馏与年均降雨量显著负相关，与上述分析结果一致。而且，西北干旱区（MAP<800 mm）ɛalk/p与年均降雨量的相关性明显好于东南湿润区（MAP>800 mm）。因此，我们认为δDalk反映了大气降水δD，但显著受干旱影响，这一影响在干旱区（比如MAP<800mm）更显著。西北地区因干旱影响强烈，δDalk或可成为潜在的雨量参数。东南地区干旱影响弱，δDalk主要反映大气降水δD，不宜作为雨量参数。

Hydrogen isotopes of n-alkanes in 55 topsoil samples collected from northwest to southeast China were analyzed. The δD values of n-alkanes (δDalk, specifically δDn-C29 and δDn-C31) showed significant positive correlations with both the δD of mean annual precipitation (MAP) and the δD of precipitation from April to October, indicating that δDalk records the δD signal of atmospheric precipitation. However, precipitation δD alone cannot explain all variations in δDalk. By analyzing the relationships between the apparent fractionation value (ɛalk/p) and relative humidity, rainfall, dryness index, temperature, as well as vegetation type, we found that ɛalk/p exhibited no significant correlation with latitudinal changes in herbaceous/woody plant types, but showed significant negative correlations with relative humidity, mean annual rainfall, and dryness index. This indicates that ɛalk/p is mainly controlled by aridity, with little influence from vegetation type. This may be because aridity enhances deuterium enrichment caused by evaporation of soil water and leaf water, while reducing deuterium depletion resulting from biosynthetic fractionation. Additionally, by integrating national-scale topsoil hydrogen isotope datasets, we found that δDalk is significantly positively correlated with atmospheric precipitation δD, and ɛalk/p is significantly negatively correlated with mean annual rainfall, which is consistent with the above analytical results. Moreover, the correlation between ɛalk/p and mean annual rainfall in the arid northwest China (MAP < 800 mm) is significantly stronger than that in the humid southeast China (MAP > 800 mm). Therefore, we conclude that δDalk reflects the δD of atmospheric precipitation, but is significantly affected by aridity, and this effect is more pronounced in arid regions (e.g., MAP < 800 mm). Due to the strong aridity influence in northwest China, δDalk has the potential to serve as a rainfall proxy. In contrast, the weak aridity influence in southeast China means that δDalk mainly reflects the δD of atmospheric precipitation, and is not suitable as a rainfall proxy.

搜集汇总

背景与挑战

背景概述

该数据集包含中国西北至东南55个表土样品的正构烷烃氢同位素数据，空间覆盖23°N至41°N，旨在分析δDalk与大气降水δD的关系，并揭示表观分馏值与干旱指标（如相对湿度和年均降雨量）的显著负相关性，表明干旱对氢同位素信号有重要影响，尤其在西北干旱区更为突出。数据集来源于地球科学研究，支持降水气候重建和干旱环境评估。