日本海沿岸の土壌および古土壌中に堆積したアジア大陸起源の広域風成塵 (日本海沿岸の更新世の古地理と古環境特集号)

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A long-range, tropospheric eolian dust transported from the Saharan desert and the Asian continent has been deposited on the terrestrial and aquatic environments in the northern hemisphere. Soil loss due to wind erosion in the arid and semiarid source areas is more significant than previously assumed. Global emission of desert dust and mineral aerosol material is estimated to amount to more than 1.0×106ton yr-1. Long-range eolian dust is an important factor in soil formation and nutrient input in many deposition areas. Physical, chemical, and mineralogical characteristics of long-range eolian dust derived from the Takla Makan and Gobi deserts and the Loess Plateau in China and their influence and significance to the soil and paleosol formations in Japan and Korea are reviewed in this paper.The long-range eolian dust in East-Asia was characterized by a predominance of soil particles 3 to 30μm in diameter. Their dominant minerals were 2:1 layer silicates, kaolinite, quartz, and feldspar. Nonallophanic andosols, red-yellow soils developed on limestones, basalts, and other diverse parent materials, and paleosols buried in paleodunes in the area along the coast of Japan Sea, were strongly influenced by the long-range eolian dust derived from China. Oxygen isotope abundance of the fine-grained quartz (1 to 10μm) isolated from soils revealed that fine quartz and 2:1 layer silicates in diverse soils and paleosols in Japan and Korea and pelagic sediments in the Japan Sea were of eolian dust origin. The eolian dust flux from the atmosphere to terrestrial environments in Japan is significant in the heavy snowfall area along the coast of Japan Sea and was more prominent in the last Glacial age than in the Holocene. Dust flux from East China Sea, Yellow Sea, and Japan Sea pelagic sediments dried during the marine regression period in the last Glacial age to soils and paleosols was also significant in Japan. Thus the desert dust phenomenon is of relevance to geophysical science in general, e. g. geography, geochemistry, climatology, soil science, ocean sedimentology, and Quaternary studies. Desert dust emission and long-range transport are useful indicators for dynamic change in the tonal circulation system, influencing the discussion of future climatic change.
日本第四紀学会の論文

日本海沿岸の土壌および古土壌中に堆積したアジア大陸起源の広域風成塵 (日本海沿岸の更新世の古地理と古環境特集号)

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