Coal and biomass burning as major emissions of NOX in Northeast China: Implication from dual isotopes analysis of fine nitrate aerosols. (1st December 2020)

• Record Type: Journal Article
• Authors: Zhao, Zhu-Yu; Cao, Fang; Fan, Mei-Yi; Zhang, Wen-Qi; Zhai, Xiao-Yao; Wang, Qian; Zhang, Yan-Lin
• Is Part Of: Atmospheric environment. Volume 242(2020)
• Publication Date: 2020-12-01
• Subjects: Aerosol -- Nitrate -- Stable isotope -- Sources -- Formation; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2020.117762
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: In recent years, there are still huge amounts of NOx emissions in the Northeast, and this inevitably increases the concentration of aerosol nitrate (NO3 − ), which plays an important role in atmospheric pollution. Because of the mixed sources of atmospheric NO3 −, it is difficult to quantify their contribution, and the use of certain means to identify their sources and pathways is critical to developing effective control measures. Since different sources of NOX have different ranges of δ 15 N values, δ 15 N is considered to be a useful tool for identifying the source of aerosol NO3 − . But isotope fractionation occurs during the conversion of NOX to NO3 −, and δ 18 O can be used to estimate its isotope fractionation value. In this study, daily PM2.5 samples were collected in four seasons from Northeast China, and their water-soluble ionic components (WSIs), δ 15 N–NO3 - and δ 18 O–NO3 - were analyzed. The isotope fractionation value of δ 15 N in which NOX was converted to NO3 − was estimated and the contribution of different sources was quantified in combination with the Bayesian model. The results showed that NO3 − was the most important inorganic ion component in the WSIs with the highest annual average ratio of 21.1%. Both δ 15 N and δ 18 O showed higher in winter (δ 15 N: 13.79‰±2.17‰; δ 18 O: 70.50‰±10.02‰) than in summer (δ 15 N: 2.69‰±2.95‰; δ 18 O: 58.67‰±4.52‰). The daytime OH pathway was considered to play a leading role in nitrate formation, with the annual average contribution of 61.0 ± 18.8%. NOx was mainly from the contribution of coal combustion (34.5%) and biomass burning (34.3%) followed by traffic (19.5%) and biological soil (11.7%). During heating periods, NOx was dominated by coal combustion with the average contribution of 46.9% whereas biomass burning was the most important contributor during non-heating periods (39.5%). Therefore, controlling coal consumption and biomass burning can drastically reduce concentration of aerosol NO3 − in Northeast China. Graphical abstract: Image 1 Highlights: Coal combustion and biomass burning dominated the production of nitrate in Northeast China. Nitrate was formed mainly through the OH radical pathway in Northeast China. In winter, coal combustion dominated the production of NOX, while in other seasons biomass burning dominated. The dominant source of nitrate during heating period and non-heating period were coal combustion and biomass burning, respectively.