Late Holocene isotope hydrology of Lake Qinghai, NE Tibetan Plateau: effective moisture variability and atmospheric circulation changes
Late Holocene isotope hydrology of Lake Qinghai, NE Tibetan Plateau: effective moisture variability and atmospheric circulation changes
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DOI：
10.1016/j.quascirev.2010.05.019
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发表时间：
2010-08-01
影响因子：
4
通讯作者：
Leng, Melanie J.
中科院分区：
文献类型：
--
作者：
Henderson, Andrew C. G.;Holmes, Jonathan A.;Leng, Melanie J.
青藏高原东北部封闭盆地青海湖的湖相碳酸盐氧同位素 (δ O-18(C)) 亚百年分辨率记录显示，过去 1500 年来存在明显的变化。水文封闭湖泊中 Delta O-18(C) 的变化通常用有效湿度的变化来解释。根据这种解释，我们的记录意味着与中世纪温暖期（MWP）相比，小冰河期（LIA）期间的有效湿度有所增加。然而，来自其他档案的独立证据强烈表明，亚洲夏季季风在 MWP 期间较强，而在 LIA 期间减弱。因此，除有效湿度（水输入与蒸发损失的平衡）以外的控制措施必定对 Delta O-18(C) 值有所贡献。我们认为青海湖的 LIA 信号是由于气温降低导致蒸发减少，加上西风降水相对重要性增加导致输入水体氧同位素组成减少所致。我们的结果警告不要对水文封闭湖泊的碳酸盐氧同位素记录进行简单化解释，并表明必须考虑所有可能的控制因素，以避免误导性的古气候重建。 (C) 2010 Elsevier Ltd. 保留所有权利。
A sub-centennial-resolution record of lacustrine carbonate oxygen isotopes (delta O-18(C)) from the closed-basin Lake Qinghai on the NE Tibetan Plateau shows pronounced variability over the past 1500 years. Changes in delta O-18(C) in hydrologically closed lakes are often interpreted in terms of changing effective moisture. Under this interpretation our record would imply increasing effective moisture during the Little Ice Age (LIA) compared to the Medieval Warm Period (MWP). However, independent evidence from other archives strongly suggests the Asian summer monsoon was stronger during the MWP and weakened during the LIA. Controls other than effective moisture (the balance of water inputs over evaporative loss) must therefore have contributed to the delta O-18(C) values. We propose the LIA signal in Lake Qinghai resulted from a reduction in evaporation caused by colder air temperatures, coupled with a decrease in oxygen isotope composition of input waters as a result of an increase in the relative importance of westerly-derived precipitation. Our results caution against simplistic interpretations of carbonate oxygen isotope records from hydrologically closed lakes and suggest all possible controlling factors must be taken into account in order to avoid misleading palaeoclimatic reconstructions. (C) 2010 Elsevier Ltd. All rights reserved.