摘要:
亚硝酸在冰晶中存在以下平衡:r="0" src="http://www.rhhz.net/qikantupian/hjhx-20090501-621.gif" /> ,导致冰晶中的亚硝酸以4种形式的N(Ⅲ):NO2-,HONO,H2ONO+和NO+存在.实验发现,四种N(Ⅲ)在冰晶中分数与pH值有很大关系:pH3,主要以NO2-和HONO形式存在;pH3,主要以HONO,H2ONO+和NO+形式存在.冰晶中的N(Ⅲ)借助以上平衡不断产生HONO并释放到大气中,导致冰晶中N(Ⅲ)不断损失.实验还发现,冰晶中N(Ⅲ)损失率随pH值的升高先升高后下降,随N(Ⅲ)初始浓度升高而升高.紫外光能使冰晶中N(Ⅲ)发生光解,但光解速率很慢,加入·OH猝灭剂也不能提高冰晶中N(Ⅲ)的光解率.
关键词:
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亚硝酸
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损失率
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H2ONO+
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NO+
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光解
Abstract:
The equilibrium equation of nitrous acid in ice:r="0" src="http://www.rhhz.net/qikantupian/hjhx-20090501-621.gif.gif" /> has demonstrated that nitrous acid(HONO)was present in ice in four different N(Ⅲ)species:NO2-,HONO,H2ONO+ and NO+,the mole fraction of which has a strong dependence on pH. At pH3,N(Ⅲ)species mainly included NO2- and HONO,while N(Ⅲ)existed by means of HONO,H2ONO+ and NO+ at pH3. HONO released from above dissociation equilibrium contributed to the loss of N(Ⅲ)in ice. The experiment results also showed that the loss percentage of N(Ⅲ)first increased then decreased with the increasing pH,and increased with the increase of initial concentration of N(Ⅲ). Moreover,we studied the photolysis of N(Ⅲ)in ice and found photolysis reaction took place under UV light,but the rate of photolysis appeared to be very slow. Addition of ·OH scavenger did not enhance its photolysis rate in ice.
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