Ca depletion in the soil column on a granite substrate on the island of Yakushima, a world natural heritage site

We investigated the vertical profile of element distributions in the soil c olumn on a granite substrate at three sites on the island of Yakushima, a w orld natural heritage site in southwestern Japan, where stream acidificatio n due to acid rain is of increasing concern. Statistical analysis shows tha t the elements in the granitic soil can be classified into three groups acc ording to their mineralogical derivations: Group 1 (K, Mg, Mn, Rb, and Nb), group 2 (Fe, Ti, Zr, Cr, and Pb), and group 3 (Ca, Na, Sr, and P), which a re related to the presence of K-feldspar and K-mica, Fe-Ti oxides, and plag ioclase and apatite, respectively. The pattern of distribution of group-1 e lements in the soil column differs slightly among the sites because of diff erences in the proportions of K-feldspar and K-mica. The organic surface so il is enriched in group-2 elements and shows a strong magnetic susceptibili ty, indicating the presence of biogenetic magnetite. At all sites, Ca and S r are intensely depleted due to the selective dissolution of plagioclase. C a depletion compared to the original granite reaches more than 90% in the C horizon, resulting in a decreasing capacity for the neutralization of acid rain and an increasing contribution of atmospheric Ca to the surface soil and vegetation.