Characteristics and budget of nitrous acid at an urban site in winter of Shanghai,China
Continuous measurements of HONO and related pollutants were conducted in the urban area of Shanghai from November 6,2022,to January 2,2023.By combining box model simulations,the concentrations,characteristics,and sources of winter HONO in Shanghai urban area were obtained.The results showed that the average concentration of HONO was(1.17±0.82)×10-9,with a concentration range of(0.078～5.32)×10-9.The average concentration of HONO in pollution days was significantly higher than that in clean days,showing an increase of approximately 67.2％.HONO exhibited diumal variation,with higher concentrations at night and lower concentrations during the day,similar to the diurnal variation of NOx.Analysis of correlations between HONOcorr and various influencing factors indicated that the heterogeneous conversion of NO2 was the main source of HONO during nighttime,while both homogeneous and heterogeneous reactions(including photo-enhanced conversion)were dominate sources during daytime.Box model simulations suggested that daytime sources of HONO primarily were photo-enhanced conversion of NO2 on ground surfaces and homogeneous reactions involving OH and NO2.The average HONO formation rates in pollution days were 0.21 and 0.16x10-9/h,respectively.During nighttime,the dominate sources were NO2 conversion on ground surfaces and primary emissions.The increase in PM2.5 and its chemical species during nighttime lead to an increased contribution from NO2 photo-enhanced conversion on various surfaces.
万方数据
维普
