Humidity Dependence of the Condensational Growth of α-Pinene Secondary Organic Aerosol Particles
Humidity Dependence of the Condensational Growth of α-Pinene Secondary Organic Aerosol Particles
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DOI：
10.1021/acs.est.1c01738
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发表时间：
2021-08-18
影响因子：
11.4
通讯作者：
Martin, Scot T.
中科院分区：
文献类型：
--
作者：
Qin, Yiming;Ye, Jianhuai;Martin, Scot T.
相对湿度(RH)对有机气溶胶颗粒凝聚生长的影响尚不完全清楚。在这里，通过在连续混合流动室内进行的一系列α-蒎烯臭氧化实验研究了RH的依赖关系，在连续混合流动室内，颗粒在给定的RH下每隔7-8小时发生一次循环生长。在5h内，在0%RH和75%RH时，粒子模直径分别平均增加了15 nm和110 nm。相应的颗粒生长系数，代表热力学驱动力和传质动力学阻力的组合，从0.35增加到2.3 nm(2)S(-1)。化学组成由O：C原子比为0.52和H：C原子比分别为0.52和1.48表征，并用质谱仪测定，不依赖于RH。气溶胶相互作用和化学模拟模型(MOSAIC)被用来通过优化凝聚分子颗粒内的扩散系数D-b来再现观察到的与尺寸和相对湿度相关的颗粒生长。当质量调节系数α为0.1时，D-b值从0%RH时的5α(-1)×10(-16)增加到75%RH时的2α(-1)x 10(-12)cm(-2)S(-1)，这突出了粒子相特性在模拟大气气溶胶粒子生长过程中的重要性。
The influence of relative humidity (RH) on the condensational growth of organic aerosol particles remains incompletely understood. Herein, the RH dependence was investigated via a series of experiments for a-pinene ozonolysis in a continuously mixed flow chamber in which recurring cycles of particle growth occurred every 7 to 8 h at a given RH. In 5 h, the mean increase in the particle mode diameter was 15 nm at 0% RH and 110 nm at 75% RH. The corresponding particle growth coefficients, representing a combination of the thermodynamic driving force and the kinetic resistance to mass transfer, increased from 0.35 to 2.3 nm(2) s(-1). The chemical composition, characterized by O:C and H:C atomic ratios of 0.52 and 1.48, respectively, and determined by mass spectrometry, did not depend on RH. The Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) was applied to reproduce the observed size- and RH-dependent particle growth by optimizing the diffusivities D-b within the particles of the condensing molecules. The D-b values increased from 5 alpha(-1) x 10(-16) at 0% RH to 2 alpha(-1) x 10(-12) cm(-2) s(-1) at 75% RH for mass accommodation coefficients alpha of 0.1 to 1.0, highlighting the importance of particle-phase properties in modeling the growth of atmospheric aerosol particles.