硝酸盐
煤燃烧产物
微粒
环境科学
环境化学
δ18O
无机离子
污染
季节性
煤
大气科学
化学
离子
稳定同位素比值
生态学
地质学
生物
有机化学
物理
量子力学
作者
Yanli Li,Yaping Geng,Xiaomian Hu,Xijie Yin
标识
DOI:10.1016/j.jes.2021.08.020
摘要
Nitrate (NO3-) has been the dominant ion of secondary inorganic aerosols (SIAs) in PM2.5 in North China. Tracking the formation mechanisms and sources of particulate nitrate are vital to mitigate air pollution. In this study, PM2.5 samples in winter (January 2020) and in summer (June 2020) were collected in Jiaozuo, China, and water-soluble ions and (δ15N, δ18O)-NO3- were analyzed. The results showed that the increase of NO3- concentrations was the most remarkable with increasing PM2.5 pollution level. δ18O-NO3- values for winter samples (82.7‰ to 103.9‰) were close to calculated δ18O-HNO3 (103‰ ± 0.8‰) values by N2O5 pathway, while δ18O-NO3- values (67.8‰ to 85.7‰) for summer samples were close to calculated δ18O-HNO3 values (61‰ ± 0.8‰) by OH oxidation pathway, suggesting that PM2.5 nitrate is largely from N2O5 pathway in winter, while is largely from OH pathway in summer. Averaged fractional contributions of PN2O5+H2O were 70% and 39% in winter and summer sampling periods, respectively, those of POH were 30% and 61%, respectively. Higher δ15N-NO3- values for winter samples (3.0‰ to 14.4‰) than those for summer samples (-3.7‰ to 8.6‰) might be due to more contributions from coal combustion in winter. Coal combustion (31% ± 9%, 25% ± 9% in winter and summer, respectively) and biomass burning (30% ± 12%, 36% ± 12% in winter and summer, respectively) were the main sources using Bayesian mixing model. These results provided clear evidence of particulate nitrate formation and sources under different PM2.5 levels, and aided in reducing atmospheric nitrate in urban environments.
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