Temperature dependence of secondary organic aerosol
Temperature dependence of secondary organic aerosol
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DOI：
10.1016/j.atmosenv.2009.04.011
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发表时间：
2009-07
影响因子：
5
通讯作者：
B. Warren;Rebecca L. Austin;D. Cocker
中科院分区：
文献类型：
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作者：
B. Warren;Rebecca L. Austin;D. Cocker
温度对环己烯和α-蒎烯臭氧分解生成二次有机气溶胶有显著影响。等温实验进行了两个系统的最低温度，278 K，形成约2.5-3倍和5-6倍的SOA形成在300 K和318 K，分别。在SOA形成完成后将环己烯系统温度改变为不同的等温实验设定点不会导致足够的冷凝/蒸发以在其他温度设定点再现SOA形成。当体系温度在实验结束时的两个设定点之间循环时，α-蒎烯体系在初始温度318 K和300 K之间表现出可逆性。对于初始温度为300 K-318 K之间的温度循环，在第一次加热循环后观察到不可逆的质量损失，在随后的温度循环之间观察到可逆性。在278 K下形成的SOA在22 K范围内是可逆的，但不能充分蒸发以匹配在300 K下形成的SOA质量。在SOA形成完成后进行的吸湿性测量表明，气溶胶的吸湿性也是温度的函数，并且气溶胶在初始生长完成后不会继续被氧化。气溶胶的半挥发性组分的不同吸湿性在实验完成后的系统温度变化期间是明显的。
Temperature was found to have a dramatic effect on secondary organic aerosol formation from two ozonolysis systems, cyclohexene and α-pinene. Isothermal experiments were conducted for both systems where the lowest temperature, 278 K, formed approximately 2.5–3 times and 5–6 times the SOA formed at 300 K and 318 K, respectively. Changing the cyclohexene system temperature to a different isothermal experimental set point after completion of SOA formation did not lead to sufficient condensation/evaporation to reproduce the SOA formation at other temperature set points. When the system temperature was cycled between two set points at the end of an experiment, the α-pinene system showed reversibility between the initial temperature 318 K and 300 K. For temperature cycles between the initial temperature of 300 K–318 K, an irreversible loss of mass is observed after the first heating cycle with reversibility observed between subsequent temperature cycles. The SOA formed at 278 K was reversible over a 22 K range but was unable to evaporate sufficiently to match the SOA mass formed at 300 K. Hygroscopicity measurements, taken after the completion of SOA formation, indicate that hygroscopicity of the aerosol is also a function of temperature and that the aerosol does not continue to be oxidized after initial growth is complete. The differing hygroscopicity of the semi-volatile component of the aerosol is evident during system temperature changes after completion of the experiment.