Research on elution mechanism of base and aluminum by acid rain from forest soil in Shiga Prefecture.

概要

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The leaching mechanism of cations and alminium from soil by acid rain were experimetally studied with soil samples collected from the A and B horizons of soil columns at 28 forest sites in Shiga Prefecture. Cation exchange reactions and the dissolution of aluminium-humus complexes were taken into consideration. Al extracted from soil samples with 0.5 M CuCl2, which is considered as Al in Aluminium-humus complexes, existed in double amount of exchangeable Al, and existed in high amounteven in soils with low level of exchangeable Al. The Gapon coefficients, KFB for Ca2++ Mg2+ and KFA1 for alminium, were calculated based on the concentrations of H+, Ca2++ Mg2+ and Al3+ in the solution extracted from the soil samples with pure water, exchangeable Ca2++Mg2+ and Al3+, and CEC. The values of KFB and KFA ranged from 102 to 103 (mol/L) -1/2 and from 102 to 105 (mol/L) -2/3, respectively. The values of KFB based on the extraction tests conducted under different pH conditions were scarcely affected by the equilibrium pH and shown to be approximately the same values as calculated with the water-extrable ion concentrations in each soil sample. The equation of equilibrium Al concentration was experimentally derived as the following equation: pAl3+=(2.69×BAR-0.21)×pH+(-12.3×BAR+5.7) where, BAR is bound Al ratio which means mole ratio of carboxyl radical chelating with Al to total carboxyl group included.
社団法人環境科学会の論文