| Research Abstract |
In the first year, a new determination method for trace amounts of HONO by flow injection analysis has been developed. HONO concentration in 17 seconds-average can be determined every 5 minutes. The detection limit is 15 ppt. With this method, it is found that decrease in HONO concentration in mid-night, peak concentration after sunrise and relatively high level of HONO in daytime. In the second year, this method is improved to continuous method and applied to measure HONO from soil. In laboratory experiment, it is found that an interaction of ammonium salts with NO_2 produces HONO.
In the evaporation process, composition in aqueous solution determines mainly fates of nitrite, ammonium, acetate and formate, and it is found that amounts of carbonate combined with calcium plays an important role for the fates of die above solutes. The freezing process affects the fate of HONO, and the theoretical solution of freezing reaction has been build up with a reaction of sulfide with hydrogen peroxide.
By researches for two years, the characteristics of HONO concentration profile can be clarified. The continuous research for this field will lead a clarification of HONO source and sink and an understanding of nitrogen cycle in the environment.
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