Matrix effects reshape organic aerosol volatility and atmospheric persistence

Area of Science:

• Atmospheric Chemistry
• Environmental Science
• Physical Chemistry

Background:

• Gas-particle partitioning of organic aerosols is governed by species volatility.
• In complex mixtures, apparent volatility can deviate from intrinsic volatility due to matrix effects.

Purpose of the Study:

• To systematically investigate component-resolved, mixture-specific volatility for over 1,500 species.
• To assess the influence of matrix composition on apparent volatility in various organic aerosol types.

Main Methods:

• Analysis of over 1,500 individual species across 33 simplified proxies and complex mixtures.
• Case study using levoglucosan (LG) to quantify volatility reduction in complex matrices.
• Application of machine-learning models to identify predictive molecular metrics for apparent volatility.

Main Results:

• Species in simplified mixtures show higher apparent volatility, approaching intrinsic values.
• Species in ambient and biomass-burning aerosols exhibit significantly reduced apparent volatility due to matrix effects.
• Levoglucosan (LG) volatility decreased by 1-4 orders of magnitude in complex mixtures.
• Mixture-dependent molecular metrics are more predictive of apparent volatility than intrinsic properties.

Conclusions:

• Matrix effects substantially suppress the apparent volatility of individual species in multicomponent organic aerosols.
• Intermolecular interactions play a critical role in gas-particle partitioning within complex aerosol systems.
• Current volatility prediction frameworks and aerosol transport models must incorporate matrix effects for improved accuracy.