• 论文 •

### 我国降水中δ18O的分布特点

• 收稿日期:1996-07-01 修回日期:1997-04-01 出版日期:1998-07-15 发布日期:1998-07-15

### DISTRIBUTIONAL FEATURES OF δ18O INPRECIPITATION IN CHINA

Zhang Xinping1, Yao Tandong2

1. 1. Department of Geography, Human Normal University, Changsha 410081;
2. Lanzhou Institute of Glaciology and Geocryology, Chinese Academy of Sciences, Lanzhou 730000
• Received:1996-07-01 Revised:1997-04-01 Online:1998-07-15 Published:1998-07-15

Abstract: China is situated in the eastern part of Eurasia and the western coast of the Pasific Ocea. Climatic diversity causes the differences in the regional distribution of stable isotopic ratios in precipitation. According to the calculation on the avaliable data, the δ18O is not completely parallel to the latitude, but shows the typical saddle distribution. There are the high δ18O in the southeast and the northwest of China. The high δ18O in the southeast of China is mainly caused by the ocean airmass in the low latitudes. But, the high value in the northwest of China is related to the dry climate condition. There are low ratios in the Northeast and in the southern Qinghai Xizang Plateau. On one hand, the low value in the Northeast is the result of temperature effect, and on the other hand, it is influenced by the latitude effect; the low values in the southern Qing Zang Plateau and the variational gradient of δ18O from the north to the south are related to the special influence of the great topography. Mean δ18O during the summer half year (Apr. to Sep.) is higher than that during the winter half year (Oct. to Mar.) in mid high latitude zones, i.e. Δδ18O>0, which shows that the temperature variation plays an important role in the seasonal variation of δ18O, whereas δ18O during the summer half year is lower than that during the winter half year in mid low latitude zones, i.e. Δδ18O<0, which shows that the seasonal replace of air mass from different origins plays an important role in the variation of δ18O. In China, the temperature effect mainly appears in mid high latitudes, and the more toward the inland continent, the closer the positive correlations. There are great parts of negative correlations in mid low latitudes and in the southern Qing Zang Plateau. The distribution of relations between δ18O and temperature is corresponded to that of Δδ18O. The amount effect appears in southeastern coastal regions, the Yunnan Guizhou Plateau and Qing Zang Plateau, which are obviously influencd by monsoon climate. The meteoric water lines (MWLs) of different regions are of certain divergence, which is closely related to the stable isotopic infractionations of the two processes, namely the evaporation of origins and the precipitation of vapor.

• P426.612