广州市夏秋季HONO污染特征及白天未知源分析

摘要

利用2015年10月和2016年7月在广州市暨南大学大气超级站开展的气态亚硝酸(HONO)和O3的质量浓度及其光解速率常数等相关参数的观测数据,对比分析了广州地区秋夏季的HONO变化规律和污染特性,估算了HONO和O3对OH自由基的贡献,并且对白天HONO未知来源进行了探讨.结果表明:广州地区秋季HONO的平均浓度为3.15μg/m3,夏季HONO的平均浓度为1.97μg/m3,秋季HONO的平均浓度是夏季的1.6倍;HONO和NO2均呈现典型的白天低,夜晚高的日变化规律;HONO光解对OH自由基的贡献在秋夏季均远大于O3对OH自由基的贡献,说明广州地区HONO光解可能是OH自由基最主要的来源;对HONO白天未知来源的收支分析表明,HONO在白天存在着重要的未知源Punknown,其对HONO浓度的白天贡献在秋季和夏季分别占到总来源的69%和49%,这一较强的未知来源经相关性分析,很可能与白天NO2的光增强反应有关.%Based on the mass concentrations and photolysis rate constant of HONO and O3 obtained at a super site in Jinan University, Guangzhou, in October, 2015 and July, 2016, this study analyzed the diurnal variation of HONO and its seasonal pollution characteristics; estimated the contributions of HONO and O3 to OH radicals; and investigated an unknown source of HONO during the daytime. The results showed that the average concentration of HONO was 3.15μg/m3 in the autumn, which was 1.6 times its concentration of 1.97μg/m3 in the summer. Both HONO and NO2 showed the typical diurnal variation pattern of low concentrations during the daytime and high concentrations during the nighttime. The contribution of HONO photolysis to OH radicals in the autumn and summer was much larger than that of O3, indicating that the photolysis of HONO in Guangzhou was probably the primary source of OH radicals. Budget analysis showed that there was an important unknown source of HONO during the daytime, and its daily contributions to HONO concentration in the autumn and summer accounted for 69% and 49% of the total source, respectively. Correlation analysis suggested that this unknown source of HONO was likely related to the light-enhanced reaction of NO2.