Physics

Geology

Meteorology

Organic chemistry

Coating

Mass fraction

Composite number

Mass concentration (chemistry)

Oceanography

Mixing (physics)

Carbon fibers

Natural rubber

Physical chemistry

Composite material

Plume

Chemistry

Materials science

Particle (ecology)

Aerosol

Carbon black

Quantum mechanics

Environmental Science & Technology

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 (kgrowth = 0.84 h–1), 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 (kloss = 0.011 h–1). 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.

Using the Black Carbon Particle Mixing State to Characterize the Lifecycle of Biomass Burning Aerosols