Stable oxygen isotope differences between the areas to the north and south of Qinling Mountains in China reveal different moisture sources
Stable oxygen isotope differences between the areas to the north and south of Qinling Mountains in China reveal different moisture sources
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DOI：
10.1002/joc.3799
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发表时间：
2014-05
期刊：
影响因子：
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通讯作者：
Wusheng Yu;T. Yao;S. Lewis;L. Tian;Yaoming Ma;Baiqing Xu;D. Qu
中科院分区：
文献类型：
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作者：
Wusheng Yu;T. Yao;S. Lewis;L. Tian;Yaoming Ma;Baiqing Xu;D. Qu
研究了青藏高原东缘秦岭以北两个站点（兰州和张掖）的日降水量δ18O变化以及秦岭以南四个站点的月降水量δ18O变化。数据显示，秦岭以南地区降水δ18O组成受冬季盛行西风和夏季亚洲季风最活跃时期的强烈影响。在北方，冬季盛行西风，δ18O 趋势与温度高度一致。夏季，秦岭山脉阻挡或削弱了亚洲季风，亚洲季风仅在最活跃的时期穿过秦岭山脉。在这些时期，以北的站经历了相对贫化的δ18O值（-5‰，甚至高达+9.2‰）。随着距海岸距离的增加，夏季降水的正向北加权平均 δ18O 梯度表明盛行西风和大陆水分循环的影响。这些严重贫化的δ18O值的频率和持续时间均由南向北递减，在张掖达到最小值，该地区可能位于采样期间的季风尾区。资料显示，秦岭山脉是青藏高原东缘的重要气候分水岭。古气候研究应考虑亚洲夏季季风和不同水分源的影响。
δ18O variability in daily precipitation at two stations (Lanzhou and Zhangye) north of the Qinling Mountains at the eastern margin of the Tibetan Plateau, China, and monthly precipitation δ18O at four stations to the south of the Qinling Mountains were examined. The data show that the δ18O composition of precipitation south of the Qinling Mountains is influenced strongly by the prevailing westerlies during winter and by the summer Asian monsoon during its most active periods. To the north, the westerlies prevail in winter, and δ18O trends coincide strongly with temperature. In summer, the Qinling Mountains block or weaken the Asian monsoon, which crosses them only during the most active periods. In these periods, the stations to the north experience relatively depleted δ18O values (−5‰, and even as high as +9.2‰). A positive northward weighted average δ18O gradient of summer precipitation with increasing distance from the coast suggests the influence of the prevailing westerlies and of continental recycling of moisture. Both the frequency of these heavily depleted δ18O values and their duration decrease from south to north, reaching minimums at Zhangye, which may have been in the monsoonal tail region during the sampling period. The data reveal that the Qinling Mountains act as an important climatic divide along the eastern margin of the Tibetan Plateau. The effects of the Asian summer monsoon and of different moisture sources should be considered for paleoclimatic studies.