2023 年 57 巻 4 号 p. 247-278
Geochemical maps of soils in Japan have been created by using 3,222 soil samples collected from a depth of 0 to 20 cm at each site. Fifty-three elements have been analyzed to reveal the abundance and spatial distribution of elements in soils of whole Japan to know the transportation mechanism of element on the surface layer. Chemical compositions in soils are considered to differ from those in stream sediments because they reflect the result of complex interactions among factors such as the origin of the soil, depositional environment, climate system, and diagenetic and weathering effects. Nevertheless, spatial distribution patterns of elements in soil fundamentally resemble those in stream sediments, which are basically controlled by underlying geology. Comparing median elemental concentrations of soils and stream sediments, soils are systematically depleted in Na, Mg, Al, K, Ca, Rb, Sr, and Ba due to their dissolution during chemical weathering process; highly concentrated in P, Cu, Cd, Sb, Hg, Pb, and Bi due to mainly anthropogenic activities. However, we find difference between chemical compositions of andosols and lowland soils in Kanto region, which are caused by differences of chemical compositions in their origins and those of weathering process to elements between soil types.
