Organic Nitrate Contribution to New Particle Formation and Growth in Secondary Organic Aerosols from α-Pinene Ozonolysis
Organic Nitrate Contribution to New Particle Formation and Growth in Secondary Organic Aerosols from α-Pinene Ozonolysis
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DOI：
10.1021/acs.est.6b00961
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发表时间：
2016-06-21
影响因子：
11.4
通讯作者：
Shiraiwa, Manabu
中科院分区：
文献类型：
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作者：
Berkemeier, Thomas;Ammann, Markus;Shiraiwa, Manabu
在臭氧氧化 α-蒎烯的流动反应器研究中，使用短寿命放射性示踪剂 N-13 研究了新颗粒形成和二次有机气溶胶 (SOA) 生长过程中有机硝酸盐产生的化学动力学。氮含量的直接定量测量表明，在初始颗粒形成过程中，有机硝酸盐约占 SOA 质量的 40%，而在颗粒生长至累积模式尺寸范围（>100 nm）时，有机硝酸盐减少至约 15%。 OH清除剂实验和动力学模型结果表明，α-蒎烯与臭氧分解产生的仲OH反应形成的有机过氧自由基是有机硝酸盐形成过程中的关键中间体。发现α-蒎烯与NO3 的直接反应对于颗粒相有机硝酸盐的形成不太重要。当相对湿度增加到80%时，SOA颗粒的氮含量略有下降。实验表明，有机硝酸盐含量与 SOA 颗粒数浓度之间存在紧密相关性，这意味着冷凝有机硝酸盐属于极低挥发性有机化合物 (ELVOC)，可能在大气纳米粒子的成核和生长中发挥重要作用。
The chemical kinetics of organic nitrate production during new particle formation and growth of secondary organic aerosols (SOA) were investigated using the short-lived radioactive tracer N-13 in flow-reactor studies of a-pinene oxidation with ozone. Direct and quantitative measurements of the nitrogen content indicate that organic nitrates accounted for similar to 40% of SOA mass during initial particle formation, decreasing to similar to 15% upon particle growth to the accumulation-mode size range (>100 nm). Experiments with OH scavengers and kinetic model results suggest that organic peroxy radicals formed by a-pinene reacting with secondary OH from ozonolysis are key intermediates in the organic nitrate formation process. The direct reaction of a-pinene with NO3 was found to be less important for particle-phase organic nitrate formation. The nitrogen content of SOA particles decreased slightly upon increase of relative humidity up to 80%. The experiments show a tight correlation between organic nitrate content and SOA particle-number concentrations, implying that the condensing organic nitrates are among the extremely low volatility organic compounds (ELVOC) that may play an important role in the nucleation and growth of atmospheric nanoparticles.