近2000年来南极菲尔德斯半岛西湖沉积物中稀土元素1/δEu特征与气候演变

The Characteristic of 1/δEu in the Sediments of West Lake with Respect to Climate Change during the Past 2000 Years, Fildes Peninsula, Antarctica

测试分析了近 2 0 0 0年来南极菲尔德斯半岛西湖沉积物中的部分稀土元素和微量元素丰度。稀土元素的分配模式表明沉积物主要来自周围的母岩风化产物。相对于Cs/Rb ,La/Yb和Sr/Ba而言 ,1/δEu随深度的变化与沉积物中反映生物强度变化的S元素丰度的波动明显一致 ,且与近 2 0 0 0年来该地区降水量的变化几乎同步。这表明尽管稀土元素Eu没有出现明显的异常变化 ,但是 ,1/δEu对历史时期的气候变化和生物活动强度有很好的响应关系 ,能够用来反演古气候环境的演变。

Characteristics of REE are commonly applied to identify the source of sediments. Nowadays some of REE specialties are found to link to climate change. Here we developed a REE method in Quaternary research. We collected the core sediment in the West Lake, located near the Chinese Great Wall Station in the maritime Antarctic using a 12cm diameter PVC pipe during the fifteenth China Antarctic Research Expedition (December 1998 March 1999). The lake core was in the length of 146cm and dating back approximately 2000 years. In the laboratory, it was sectioned at 5.0 cm intervals. And 15 subsamples were selected by 10 cm intervals, to analyze the concentrations of REE and trace elements using the Neutron Activation method. The results showed that (1) Waterside basalt rock weathering was the main source of the sediments of the West Lake, according to the distribution model of REE; (2) Changes in the ratios of Cs/Rb, La/Yb and Sr/Ba against depth did not correspond to climate change in this area; (3) The fluctuation of 1/δEu versus depth profile was significantly similar to the variation of sulfur in the sediments, which was well documented related with biological activity. The change in 1/δEu was, moreover, in accordance with a 2000 year record of the precipitation in this region. The authors, therefore, proposed that 1/δEu was an ideal proxy in the reconstruction of the palaeoclimate change. Based upon the change in 1/δEu, it was warm and humid on the Fildes Peninsula during 1 150～1 800 years before present (yr BP), in this period the biological activity was strong, after that the temperature gradually decreased.