摘要
根据实测资料计算，我国东南部地区以及西北地区的大气降水中δ１８Ｏ较高，东北和青藏高原南部的δ１８Ｏ则较低。在我国，温度效应主要出现在中高纬度大陆内部，降水量效应则主要分布在东南沿海、云贵高原和青藏高原。这些地区明显受季风气候的影响。不同地区的大气水线存在一定的差异，它们与水汽在源地的蒸发以及水汽凝结致雨两个过程的稳定同位素分馏密切相关。
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 δ 18 O is not completely parallel to the latitude, but shows the typical saddle distribution. There are the high δ 18 O in the southeast and the northwest of China. The high δ 18 O 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 δ 18 O from the north to the south are related to the special influence of the great topography. Mean δ 18 O 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. Δδ 18 O>0, which shows that the temperature variation plays an important role in the seasonal variation of δ 18 O, whereas δ 18 O during the summer half year is lower than that during the winter half year in mid low latitude zones, i.e. Δδ 18 O<0, which shows that the seasonal replace of air mass from different origins plays an important role in the variation of δ 18 O. 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 δ 18 O and temperature is corresponded to that of Δδ 18 O. 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.
出处
《地理学报》
EI
CSSCI
CSCD
北大核心
1998年第4期356-364,共9页
Acta Geographica Sinica
