Study of Effect of Freezing-Thawing Process on the Mechanizm of Acid Rain Generation

通过对水溶液的冷冻，发现亚硝酸盐与溶解氧的反应异常加速。然后对冻结加速效应的机理进行了研究。考察了冷冻过程对环境反应的影响。加速效应很可能是由于以下机制造成的。反应物被排除在生长冰晶的溶液之外。每种反应物的排除程度不同。阳离子和阴离子排除的不平衡导致冰和溶液之间的电位差。带正电的冰吸引阴离子（亚硝酸盐）。随着冰的增长，亚硝酸盐和氧气集中在冰与溶液的界面上。高浓度的反应物加速了反应。还观察到从硝酸盐生成反应的加速。但雨中亚硝酸盐的浓度很低，并且发现雨的pH值不受冻结的影响。在ikoma山，雾中亚硝酸盐浓度很高（>0.1mmol/L）， pH值降低了0.1以上。由于冻结过程在环境中不是异常过程，因此认为冻结加速在环境中起着重要的作用。

The reaction of nitrite with dissolved oxygen had been found to be abonormally accelerated by freezing of aqueous solution. Then the mechanizm of acceleration effect of freezing was studied.and the role of freezing process on the reaction in environment was investigated. The acceleration effect is most likly due to the follwing mechanizm. Reactants were excluded from growing ice crystals to solution. The extents of exclusion of each reactant were difference. The unbalance of the exclusion of cations and anions causes the potential difference between ice and solution. The positively charged ice attracts anions (nitrite). Nitrite and oxygen are concentrated at the interface of ice and solution with growing ice. The reaction is accelerated by very high concentrated reactants.The acceleration of the reaction to from nitrate was also observed. However the concentrations of nitrite in rain are very low, and it is found that the pH of rain was not affected by freezing. The high concentration of nitrite in fog (>0.1mmol/L) was obtained at Mt.Ikoma.In this case the pH was depressed more Than 0.1. Since the freezing process is not an abnormal process in environment, it is considered that the acceleration by freezing plays an important role in environment.