|Budget Amount *help
¥3,100,000 (Direct Cost : ¥3,100,000)
Fiscal Year 1994 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1993 : ¥2,300,000 (Direct Cost : ¥2,300,000)
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.