Measurement of heterogeneous uptake of NO2 on inorganic particles,sea water and urban grime

• 作者: Chuan Yu Zhe Wang Qingxin Ma Likun Xue Christian George Tao Wang
• 来源期刊: 环境科学学报（英文版）
• 年，卷（期）: 2021,（8）
• 所属期刊栏目: Regular articles
• 页码范围: 124-135
• 页数: 12页
• 语种: 英文

摘要

Heterogeneous reactions of NO2 on different surfaces play an important role in atmospheric NOx removal and HONO formation,having profound impacts on photochemistry in polluted urban areas.Previous studies have suggested that the NO2 uptake on the ground or aerosol surfaces could be a dominant source for elevated HONO during the daytime.However,the uptake behavior of NO2 varies with different surfaces,and different uptake coefficients were used or derived in different studies.To obtain a more holistic picture of heterogeneous NO2 uptake on different surfaces,a series of laboratory experiments using different flow tube reactors was conducted,and the NO2 uptake coefficients (γ) were determined on inorganic particles,sea water and urban grime.The results showed that heterogeneous reactions on those surfaces were generally weak in dark conditions,with the measured γ varied from＜10-8 to 3.2 × 10-7 under different humidity.A photo-enhanced uptake of NO2 on urban grime was observed,with the obvious formation of HONO and NO from the heterogeneous reaction.The photo-enhanced γ was measured to be 1.9 × 10-6 at 5％ relative humidity (RH)and 5.8 × 10-6 at 70％ RH on urban grime,showing a positive RH dependence for both NO2 uptake and HONO formation.The results demonstrate an important role of urban grime in the daytime NO2-to-HONO conversion,and could be helpful to explain the unknown day-time HONO source in the polluted urban area.