Effects of climate factors on spatiotemporal variation in carbon and oxygen isotope ratios in Korean rice.

In this study, we investigated the climatic factors controlling the spatial distribution and annual variation of δ¹³C and δ¹⁸O values in Korean rice on a national scale. A total of 480 Korean rice samples were collected in 2016, 2017, and 2018. The spatial distribution of δ¹³C and δ¹⁸O values of Korean rice was unclear, with significant inter-annual variability observed at the national scale. Isotopic variability was closely related to climatic conditions, especially precipitation. Overall, rice δ¹³C values were negatively correlated with precipitation and sunshine hour. Rice δ¹⁸O values were also strongly negatively correlated with precipitation. Increased precipitation during the growing season (August to October) was mainly linked to lower δ¹³C and δ¹⁸O values due to plant physiological processes and/or the contribution of water from different sources to irrigation. All rights reserved, Elsevier.