大气硝酸盐由于是PM2.5的重要成分之一而受到越来越多的关注。了解PM2.5中硝酸盐的来源和形成机理,对于采取有效措施防控大气中氮氧化物的排放,减少雾霾的形成至关重要。在这项研究中,从赣州采集PM2.5样本，中国东南部的一个内陆城市，在夏季和冬季。测定了PM2.5和NO3-的浓度，并分析了NO3-（δ15N-NO3-和δ18O-NO3-）的同位素组成，以量化PM2.5中不同排放源和硝酸盐形成途径的相对贡献。结果表明，夏季PM2.5和NO3-浓度较低（39.80±11.10μg·m-3和1.79±0.70μg·m-3），而冬季较高（69.85±29.58μg·m-3和10.83±9.89μg·m-3）。夏季δ18O-NO3-和δ15N-NO3-的值范围为42.84‰至56.80‰，-11.17‰至-2.08‰，冬季从55.86‰到78.66‰，从-10.63‰到-1.88‰，分别。δ15N-NO3-结合贝叶斯同位素混合模型的结果表明,汽车尾气的相对贡献,土壤微生物活性，生物质燃烧和燃煤发电厂占59.3%，28.5%,夏季为8.7%和3.4%，而65.1%，20.1%,冬季为10.6%和4.1%,分别。δ18O-NO3-结合贝叶斯同位素混合模型的结果表明，途径1（P1）（NO2·OH）的可能相对贡献，途径2(P2)(NO3+HC)和途径3(P3)(N2O5+H2O)为73.5%,夏季12.4%和14.1%，而41.6%，冬季为28.9%和29.5%,分别。此外，当NO3-浓度较高时，P2和P3的贡献更大，表明P2和P3对PM2.5中硝酸盐的形成具有重要意义，尤其是在冬季。
Atmospheric nitrate has been attracting increasing attention because it is one of the important components of PM2.5. Understanding the sources and formation mechanism of nitrate in PM2.5 is essential to take effective measures to prevent and control the emission of nitrogen oxides in the atmosphere and reduce the formation of haze. In this study, PM2.5 samples were collected from Ganzhou, an inland city in southeast China, during summer and winter. The concentrations of PM2.5 and NO3- were determined, and the isotopic compositions of NO3- (δ15N-NO3- and δ18O-NO3-) were analyzed in order to quantify the relative contributions of different emission sources and formation pathways of nitrate in PM2.5. The results showed that PM2.5 and NO3- concentrations were lower in summer (39.80 ± 11.10 μg·m-3 and 1.79 ± 0.70 μg·m-3) while higher in winter (69.85 ± 29.58 μg·m-3 and 10.83 ± 9.89 μg·m-3). The values of δ18O-NO3- and δ15N-NO3- ranged from 42.84‰ to 56.80‰ and from -11.17‰ to -2.08‰ in summer, while from 55.86‰ to 78.66‰ and from -10.63‰ to -1.88‰ in winter, respectively. The results of δ15N-NO3- combined with Bayesian isotope mixing model showed that the relative contributions of vehicle exhaust, soil microbial activity, biomass combustion and coal fired power plants were 59.3%, 28.5%, 8.7% and 3.4% in summer, while 65.1%, 20.1%, 10.6% and 4.1% in winter, respectively. The results of δ18O-NO3- combined with Bayesian isotope mixing model showed that the possible relative contributions of pathway 1 (P1) (NO2 + ·OH), pathway 2 (P2) (NO3 + HC) and pathway 3 (P3) (N2O5 + H2O) were 73.5%, 12.4% and 14.1% in summer, while 41.6%, 28.9% and 29.5% in winter, respectively. Moreover, P2 and P3 contributed more when NO3- concentrations were higher, suggesting that P2 and P3 were of significance to the formation of nitrate in PM2.5, especially during winter.
