Concurrent dominant pathways of multifunctional products formed from nocturnal isoprene oxidation.
Concurrent dominant pathways of multifunctional products formed from nocturnal isoprene oxidation.
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DOI：
10.1016/j.chemosphere.2023.138185
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发表时间：
2023-02
期刊：
影响因子：
8.8
通讯作者：
Haiwei Li;L. Cui;Yu Huang;Yunjiang Zhang;Junfeng Wang;Mindong Chen;X. Ge
中科院分区：
文献类型：
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作者：
Haiwei Li;L. Cui;Yu Huang;Yunjiang Zhang;Junfeng Wang;Mindong Chen;X. Ge
关于夜间二次有机气溶胶(SOA)形成的主要化学途径的确定仍然不明确，氮氧化物(NOx)总是通过这种途径影响挥发性烯烃的氧化。在此，对不同氮氧化物(NO2)混合比例下的暗异戊二烯臭氧化反应进行了全面的室内模拟，以检测多种功能化的异戊二烯氧化产物。此外，氧化过程是由氮自由基(NO3)和小羟基自由基(OH)同时驱动的，最初在异戊二烯上启动臭氧(O3)环加成反应，而不考虑NO2，以快速形成第一代氧化产物，即羰基和Criegee中间体(CI)，指的是羰基氧化物。它们还可以发生复杂的自身和交叉反应，产生烷基过氧基(RO2)。与C5H10O3示踪剂的产率相对应，夜间弱的OH途径被归功于异戊二烯的臭氧分解，但被独特的N03化学抑制。在异戊二烯臭氧分解后，NO3在夜间SOA的形成中起到了重要的辅助作用。随后生产的气相硝氧羰基化合物(第一代硝酸盐)在相当大的有机硝酸盐(RO2NO2)生产中占据主导地位。相比之下，异戊二烯二羟基二硝酸酯(C5H10N2O8)在NO2升高的情况下表现突出，与典型的第二代硝酸盐有关。这样，暗SOA的产生数浓度被提高到约1.8亿×10~4 cm−~3，但与过量高NO2条件呈非线性关系。这项研究为多官能团化合物从烯烃氧化到构成夜间SOA的重要性提供了有价值的见解。
Determination of dominant chemical pathways toward the formation of nocturnal secondary organic aerosols (SOA) remains ambiguous by which nitrogen oxides (NOx) always affect oxidation of volatile alkenes. Here, comprehensive chamber simulations on dark isoprene ozonolysis were conducted under different nitrogen dioxides (NO2) mixing ratios to exam multiple functionalized isoprene oxidation products. Aside from that the oxidation processes were concurrently driven by nitrogen radical (NO3) and small hydroxyl radicals (OH), ozone (O3) cycloaddition at isoprene was launched initially regardless of NO2to rapidly form first-generation oxidation products, i.e., carbonyls and Criegee intermediates (CI) referred to carbonyl oxides. They could further undergo complicated self- and cross-reactions to produce alkylperoxy radicals (RO2). Corresponding to yields of the C5H10O3tracer, weak OH pathway at night was credited to ozonolysis of isoprene but suppressed by unique NO3chemistry. Following the ozonolysis of isoprene, NO3played a crucial supplementary role in nighttime SOA formation. The ensuing production of gas-phase nitrooxy carbonyls (the first-generation nitrates) became dominant in the production of a sizeable pool of organic nitrates (RO2NO2). By contrast, isoprene dihydroxy dinitrates (C5H10N2O8) were outstanding with the elevated NO2, related to typical second-generation nitrates. As such, the yielding number concentrations of dark SOA were promoted to approximately 1.8 × 104cm−3but presented a nonlinear relation with excess high-NO2condition. This study provides valuable insights into importance of multifunctional organic compounds from alkene oxidation to constitute nighttime SOA.