Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hong Kong 999077, China.
CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, P. R. China.
Environ Sci Technol. 2023 Oct 31;57(43):16456-16464. doi: 10.1021/acs.est.3c04886. Epub 2023 Oct 20.
Nitrous acid (HONO) is a reactive gas that plays an important role in atmospheric chemistry. However, accurately quantifying its direct emissions and secondary formation in the atmosphere as well as attributing it to specific nitrogen sources remains a significant challenge. In this study, we developed a novel method using stable nitrogen and oxygen isotopes (δN; δO) for apportioning ambient HONO in an urban area in North China. The results show that secondary formation was the dominant HONO formation processes during both day and night, with the NO heterogeneous reaction contributing 59.0 ± 14.6% in daytime and 64.4 ± 10.8% at nighttime. A Bayesian simulation demonstrated that the average contributions of coal combustion, biomass burning, vehicle exhaust, and soil emissions to HONO were 22.2 ± 13.1, 26.0 ± 5.7, 28.6 ± 6.7, and 23.2 ± 8.1%, respectively. We propose that the isotopic method presents a promising approach for identifying nitrogen sources and the secondary formation of HONO, which could contribute to mitigating HONO and its adverse effects on air quality.
亚硝酸（HONO）是一种活性气体，在大气化学中起着重要作用。然而，准确量化其在大气中的直接排放和二次形成，并将其归因于特定的氮源仍然是一个重大挑战。在本研究中，我们开发了一种使用稳定的氮和氧同位素（δN；δO）的新方法，用于分配华北地区城市环境中的大气 HONO。结果表明，二次形成是白天和夜间 HONO 的主要形成过程，其中 NO 异相反应在白天贡献了 59.0±14.6%，在夜间贡献了 64.4±10.8%。贝叶斯模拟表明，煤炭燃烧、生物质燃烧、车辆排放和土壤排放对 HONO 的平均贡献分别为 22.2±13.1%、26.0±5.7%、28.6±6.7%和 23.2±8.1%。我们提出，同位素方法为识别氮源和 HONO 的二次形成提供了一种有前途的方法，这有助于减轻 HONO 及其对空气质量的不利影响。
