Study of effect of drying of droplets in the environment on material cycle-Dependence of size of droplets on the reaction pathway-

露水中含有高浓度的亚硝酸盐和铵离子。亚硝酸和氨气在夜间被露水溶解，大气中的浓度下降。亚硝酸在大气光化学中起着非常重要的作用，因为它是清晨OH自由基的主要来源。大气中亚硝酸浓度的降低抑制了大气的光活性，预计臭氧浓度也会降低。在本研究中，我们发现当露水形成时，大气中亚硝酸盐浓度降低，而露水中的亚硝酸盐浓度很高，亚硝酸盐与露水中的铵发生分解反应生成N_2。此外，监测数据还发现，清晨臭氧浓度在结露时低于不结露时。臭氧浓度的下降也得到了CBM-IV箱模式计算的证实。我们发现，干燥后的露水中亚硝酸盐的命运随着液滴大小的不同而变化。亚硝酸盐以干盐的形式存在或以HONO的形式蒸发到大气中，或转化为NO和NO_2，或与铵离子反应生成N_2。当干燥速度较快时，N_2产量占主导地位。真正的露珠体积很小，日出后露珠干得很快，因此露珠中的亚硝酸盐大部分分解为N_2。露水形成时，大气中的亚硝酸盐溶解在露水中，而当露水干燥时，亚硝酸盐分解成N2，导致上午大气中HONO浓度降低，臭氧浓度降低。晴天和无风无云天气会出现露珠，预计在这种气象条件下臭氧浓度会增加。从目前的研究推测，在真实环境中，露水的形成降低了大气中的臭氧浓度。

Dew contains high concentrations of nitrite and ammonium ions. Nitrous acid and ammonia gases are dissolved in dew at night, and the concentrations in the atmosphere decrease. Nitrous acid plays a very important role in the atmospheric photochemistry since it is a main OH radical source in the early morning. The decrease in the concentration of nitrous acid in the atmosphere depresses the photo-activity of the atmosphere, and ozone concentration is expected to decrease. In the present research, we found that nitrous acid concentration in the atmosphere decreases when dew forms, the concentration of nitrite in the dew is very high, and nitrite is decomposes to react with ammonium in the dew to produce N_2. Furthermore, we found that ozone concentration in the morning is lower when the dew forms than that when the dew does not form from the monitoring data. The decrease in ozone concentration was also confirmed by the CBM-IV box model calculations.We found that the fate of nitrite in the dew after drying changes with the difference in droplet size. Nitrite remain as dried salts or evaporate into the atmosphere as HONO, convert to NO and NO_2, or produce N_2 by reacting with ammonium ion. When the drying speed is fast, N_2 production was dominant. The size of real dew is very small, and the dew dries very quickly after sunrise, and therefore, most nitrite in the dew decomposes to N_2. When the dew forms, nitrous acid in the atmosphere is dissolved in dew, but nitrite is decomposed to N2 when the dew dries, as a result, the concentration of HONO in the atmosphere in the morning decreased and the ozone concentration decreases. Dew forms in fine day and no wind and no cloud day, and the ozone concentration is expected to increased under this meteorological condition. From the present study, it is speculated that the dew formation depress the ozone concentration in the atmosphere in the real environment.