多元素プロファイリング分析によるバイカル湖湖底柱状堆積物の古環境変動解析

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Lake Baikal, the oldest and deepest freshwater lake in the world, holds 5000〜10000 m depth of sediments, corresponding to a record of a 20〜30 Ma (million years) period. In the present study, paleo-environmental changes of the Eurasian continent during the past 5 Ma were investigated by performing a multielement determination of the major-to-ultratrace elements in the sediment core samples from Lake Baikal by ICP-AES and ICP-MS. As a result, the vertical profiles of 43 elements in two cores, BDP 93-2 and 96-1, were obtained in concentration ranges from % to sub-μg g^<-1>, and the following paleo-environmental changes were elucidated: (1) The profiles of the Na (Mg, Ca)/AI ratios suggest that a transition of atmospheric cycling triggered by rapid upheaval of the Himalayas occurred about 2.5〜3 Ma ago. (2) A spectral analysis of the elemental records shows the Milankovitch cycles, the dominant mechanisms for the periodical climatic changes during the past 1 Ma. (3) The concentration profile of Si shows a quite good correlation with oxygen isotope records (δ^<18>O) of deep-sea sediments, which are indices of the temperature changes of the seawater/earth. Furthermore, a preliminary study on sedimentation processes was carried out by an elemental speciation analysis of the sediments.
社団法人日本分析化学会の論文
1999-09-05