TROPOSPHERIC EOLIAN DUST ORIGIN OF RED-YELLOW SOILS IN NANSEI-SYOTO

对南西昭远的红土和黄壤群、第四纪和古生代千枚岩以及冲绳海槽、南西昭远海沟和奄美高原的活塞岩心进行了氧和碳同位素研究。石英的氧碳同位素比值，白云母和方解石表明，石英和白云母是风成尘的产物。岩手火山火山灰沉积物的分析资料（90- 130 ka）表明，风尘主要沉积于20- 34 ka和50- 70 ka，末次冰期晚期风尘通量估计为4cm/1，一千年。根据蛋白石植硅体组成和风尘含量估算了近10年来植被和气候的变化，结果表明，中国中部和北方地区近期雨水pH值和Ca浓度均高于南方地区。我们的数据表明，方解石的风尘消耗中和中国和韩国的雨水中的酸性成分。近代从中国输送到日本的风尘中含有少量方解石，说明其对日本酸雨的中和能力较低。

Oxygen and carbon isotopic studies of the Red and Yellow soil Group, Quaternary and Paleozoic phyllite in the Nansei Syoto and piston cores in the Okinawa Trough, the Nansei Syoto Trench, and the Amami Plateau were carried out. The oxygen and carbon isotopic rations of quartz, muscovite and calcite indicated that quartz and muscovite were of eolian dust origin.Analytical data of the Iwate volcano tephra deposits after the fall of the Toya Ash (90-130ka) indicated that eolian dust was mainly deposited 20-34ka and 50-70ka and that the flux of eolian dust during the late period of the Last Glacial age was estimated to be 4cm/1,000 years. The changes of vegetation and climate were also estimated by using opal phytolith composition and eolian dust content.The recent rainwater in the central and northern regions of China shows higher pH values and Ca concentrations than southern region of China. Our data showed that calcite in the eolian dust was consumed to neutralize acidic components in Chinese and Korean rainwater. Recent eolian dust transported from China to Japan contains a small amount of calcite, suggesting that it has a low neutralization capacity to acid rain in Japan.