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

对冲绳海槽、西南海沟和天美高原的红黄壤群、第四纪和古生代千层岩以及活塞岩心进行了氧碳同位素研究。石英、白云母和方解石的氧碳同位素比值表明，石英和白云母的成因为风成尘。托谷火山灰沉降后（90-130ka）岩手火山火山灰沉积物分析资料表明，风成尘主要沉积在20-34ka和50-70ka，末次冰期晚期风成尘通量估计为4cm/ 1000年。利用蛋白石植物岩组成和风成尘含量估算了植被和气候的变化。中国中北部地区近期雨水pH值和Ca浓度高于南方地区。我们的数据表明，风沙中的方解石被消耗来中和中国和韩国雨水中的酸性成分。近期从中国运至日本的风沙中含有少量方解石，表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.