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We present the results of a 3‐year monitoring programme of the stable isotope composition of lake water and precipitation at Taozi Lake, in the East Asian monsoon region of China. Our aims were to reveal the spatiotemporal pattern of variation of stable isotopes in a small closed‐basin lake and to quantitatively determine the impacts of precipitation and evaporation on the stable isotope composition of lake water under a humid monsoon climate. In the time domain, the stable oxygen isotopic ratio of the lake water (δ18OL) exhibited substantial seasonal and interannual variations, but the isotope variations between different precipitation events substantially exceeded seasonal and interannual variations. Compared with the stable isotopes in precipitation, δ18OL was substantially positive and dL was negative. In the space domains, the lake water was homogeneously mixed. Indicated by statistic analyses, precipitation plays a dominant role in dynamic of the lake stable isotope during precipitation events of relatively large magnitude, whereas the effect of evaporation is dominant during smaller precipitation events. Results advance our understanding of the stable isotope change rule in the process of lake water evaporation, and it is helpful to identify the climatic significance recorded in stable isotopic compositions of lake bottom sediments. [ABSTRACT FROM AUTHOR]

Continuous measurements were made of isotopic compositions in atmospheric water vapor ( δ v ) and in atmospheric precipitation ( δ p ) near the surface in the subtropical monsoon region (Changsha, China) from October 2014 to March 2017 to investigate the change characteristics of vapor isotopes and their interactions with precipitation isotopes. On a diurnal time scale, the δ 18 O v values were more negative in the daytime and more positive at night, and the change in d v was reversed during non-rainy days; however, the δ 18 O v values were more positive in the daytime and more negative at night, and the variation in d v was not significant during rainy days. On a seasonal time scale, affected by distinctive moisture sources, the vapor isotopes had obvious seasonal variations, with higher δ 18 O v and d v values occurring in cold seasons than in warm seasons. There were generally consistent and significant negative linear relationships of d v with temperature and absolute humidity, but the linear relationships between δ 18 O v and meteorological factors were variable on the different time scales, which was closely associated with the local weather conditions on the short time scales from diurnal to intra-seasonal and movements of air masses with distinct thermodynamic properties on seasonal and sometimes intra-seasonal time scales. Although the change trend of daily δ 18 O v closely approximated that of δ 18 O p , δ 18 O p experienced significant relative enrichment compared to δ 18 O v , with an average enrichment of 9.18‰. Overall, the isotopic compositions of atmospheric water vapor were in equilibrium with those of precipitation while rainfall events occurred, except for those in the cold season in 2014, and when tracing short-duration weather events, δ 18 O v provided more details and information related to weather processes than δ 18 O p . [ABSTRACT FROM AUTHOR]