Dissolution of feldspar and pyroxene in Kanto-loam and the evaluation of Goldich's weathering series

摘要

Goldich's weathering series (Goldich, 1938) is consistent with the results of thermochemical calculation on solubility of silicates as a function of partial pressure of carbon dioxide and also the rate of dissolution of silicates experimentally determined. However, it was found that this weathering series, solubility and dissolution rate of silicates are inconsistent with the rate of dissolution of Ca centre dot Na-feldspar and pyroxene in Kanto-loam. Goldich's weathering series, solubility and dissolution rate of Ca centre dot Na-feldspar and pyroxene indicate that Ca centre dot Na-feldspar is more stable or similar to Mg-pyroxene in the weathering series. However, Ca centre dot Na-feldspar in the Kanto-loam was suffered more intense weathering than pyroxene. This inconsistency is interpreted in terms of the rapider rate of dissolution of Ca centre dot Na-feldspar than pyroxene in organic ligand-rich soil water in near-surface environment, suggesting that organic acids are important for controlling the dissolution of Ca centre dot Na-feldspar.