|Budget Amount *help
¥2,600,000 (Direct Cost : ¥2,600,000)
Fiscal Year 1996 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1995 : ¥1,900,000 (Direct Cost : ¥1,900,000)
Integrating the distributed parameter model with respect to the space varialble, a lumped parameter model has been obtained. This is because the effect of drop-phase diffusion on rain drop acidity is small. This simple model contains chemical reaction and mass transfer terms. Then it considers the dissociation and oxidation reactions, which increase rain drop acidity, and the gas absorption. Using this lumped parameter model, the numerical simulations are executed with respect to the following matters as : (1) the effect of drop-phase oxidation on the acid rain formation, when SO2 (g) and H2O2 (g) are absorbed concurrently ; and (2) the acidification of rain drops by the absorption of nitrogen oxides gas. The result of simulations shows that : (1) the drop-phase oxidation by H2O2 (g) enhances the acidity of rain drops, although the equilibrium pH is not changed ; and (2) NOx (g) is not absorbeb easily and the contribution of it to the rain drop acidity is small compared with SO2 (g), although HNO3 (g) transformed from NOx (g) has stronger potential to acidify rain drops than SO2 (g).
The simulations by ditributed parameter model, which takes the electromigration term in addition to the abovementioned terms, disclose that the electromigration of ions makes the concetration of H+ more higher than the concentration estimated by neglecting the electromigration. The distribution of H+ concentration tends to uniform under the electrical potential field induced by the ions formed in rain drops. The electric potential is higher at the drop center than at the drop surface.