Metallic and Crustal Elements in Biomass-Burning Aerosol and Ash: Prevalence, Significance, and Similarity to Soil Particles
Biomass-burning events (i.e., wildfires) are a major source of atmospheric aerosol and are predicted to increase due to climate change. The resulting biomass-burning aerosol (BBA) has significant near-source impacts. Moreover, it can persist in the troposphere for weeks and undergo long-range transport and even injection into the stratosphere.
Leif Jahn and co-workers investigated the morphology and composition of laboratory-generated BBA and bottom ash particles from authentic fuels using transmission and scanning electron microscopy (TEM and SEM). Single-particle inductively coupled plasma time-of-flight mass spectrometry (sp-ICP-TOFMS) using TOFWERK’s icpTOF was applied for the multielement characterization of single particles.
The study found that BBA composition is dominated by carbonaceous and salt material, consistent with past measurements, but also contains particles with small amounts of mineral regions. Ash particles were found to be mixtures of carbonaceous and mineral matter while also containing regions of relatively pure mineral phases. As such, both BBA and ash particles bear similarities to natural soil particles.
The authors conclude that further development of reliable measurement methods for and estimates of combustion-derived mineral particles will be necessary to understand the abundance and impacts of these particles. They suggest that certain elemental markers (e.g., Zn or Ti), and ratios thereof, may be useful for estimating the relative abundances of combustion-derived versus soil mineral particles.