Sedlacek Arthur J, Lewis Ernie R, Onasch Timothy B, Zuidema Paquita, Redemann Jens, Jaffe Daniel, Kleinman Lawrence I
Brookhaven National Laboratory, Upton, New York 11973, United States.
Aerodyne Research, Inc., Billerica, Massachusetts 01821, United States.
Environ Sci Technol. 2022 Oct 18;56(20):14315-14325. doi: 10.1021/acs.est.2c03851. Epub 2022 Oct 6.
The lifecycle of black carbon (BC)-containing particles from biomass burns is examined using aircraft and surface observations of the BC mixing state for plume ages from ∼15 min to 10 days. Because BC is nonvolatile and chemically inert, changes in the mixing state of BC-containing particles are driven solely by changes in particle coating, which is mainly secondary organic aerosol (SOA). The coating mass initially increases rapidly ( = 0.84 h), then remains relatively constant for 1-2 days as plume dilution no longer supports further growth, and then decreases slowly until only ∼30% of the maximum coating mass remains after 10 days ( = 0.011 h). The mass ratio of coating-to-core for a BC-containing particle with a 100 nm mass-equivalent diameter BC core reaches a maximum of ∼20 after a few hours and drops to ∼5 after 10 days of aging. The initial increase in coating mass can be used to determine SOA formation rates. The slow loss of coating material, not captured in global models, comprises the dominant fraction of the lifecycle of these particles. Coating-to-core mass ratios of BC particles in the stratosphere are much greater than those in the free troposphere indicating a different lifecycle.
利用飞机以及对羽流年龄从约15分钟到10天的黑碳混合状态的地面观测，研究了生物质燃烧产生的含黑碳（BC）颗粒的生命周期。由于黑碳是不挥发且化学惰性的，含黑碳颗粒混合状态的变化仅由颗粒包覆层的变化驱动，而包覆层主要是二次有机气溶胶（SOA）。包覆层质量最初迅速增加（ = 0.84小时），然后在1 - 2天内保持相对恒定，因为羽流稀释不再支持进一步增长，之后缓慢下降，直到10天后仅约30%的最大包覆层质量留存（ = 0.011小时）。对于具有100纳米质量等效直径黑碳核心的含黑碳颗粒，包覆层与核心的质量比在几小时后达到最大值约20，并在老化10天后降至约5。包覆层质量的初始增加可用于确定二次有机气溶胶的形成速率。全球模型未捕捉到的包覆层材料的缓慢损失，构成了这些颗粒生命周期的主要部分。平流层中黑碳颗粒的包覆层与核心质量比远大于对流层自由大气中的比值，这表明其生命周期不同。
