A 130-ka reconstruction of precipitation on the Chinese Loess Plateau from organic carbon isotopes

We study the relationship between organic carbon isotopes (δ¹³C_TOC) in soil and mean annual precipitation (MAP) in the East Asian monsoon area by combining the results of carbon isotope studies of plants, C₄/C₃ ratios, and precipitation in the modern ecosystem of the Chinese Loess Plateau. Based on this relationship, we estimate the amount of paleoprecipitation that has occurred in the southeastern part of the Loess Plateau since the last interglacial stage using the carbon isotopic compositions of the soil organic matter (SOM). The results show that the annual precipitation in that region was high during the interglacial stages, with a maximum value of 850 mm, and that it decreased during the last glacial stage to a minimum value of 350 mm. We suggest that the use of organic carbon isotopic composition in paleosol sediments is a reliable method for reconstructing paleoprecipitation due to the clear relationships between soil δ¹³C_TOC, C₄/C₃ abundance, and precipitation in modern ecosystems.