Adapting the profile model to calculate the critical loads for East Asian soils by including volcanic glass weathering and alternative aluminum solubility system

Adaptation of the steady-state soil chemistry model PROFILE was studied, on the following two parts, to calculate the critical loads for East Asian so ils: (1) Dissolution rate coefficients of volcanic glass were derived from published experimental data, and calculated field weathering rate was compa red with the rate estimated based on Sr isotope analysis. When BET surface area of sand fraction was regarded as mineral surface area, the calculated rates fairly agreed with the estimate, suggesting that sand fraction surfac e area is a reasonable estimate of weatherable mineral surface area of volc anic soils. (2) In repeated leaching experiments, Al solubility of a number of Japanese soils was explained by a model which assumed complexation of A l to soil organic matters. Such an Al solubility model is more appropriate for predicting soil chemistry than apparent gibbsite dissolution equilibriu m.