Terpene Composition Complexity Controls Secondary Organic Aerosol Yields from Scots Pine Volatile Emissions

Area of Science:

• Atmospheric Chemistry
• Climate Science
• Environmental Science

Background:

• Secondary organic aerosol (SOA) significantly impacts climate through radiative effects and cloud formation.
• Current SOA models often oversimplify atmospheric chemistry, using limited volatile organic compounds.
• Real-world atmospheric complexity, particularly plant emissions, is crucial for accurate SOA modeling.

Purpose of the Study:

• Investigate SOA formation from complex Scots pine (Pinus sylvestris) emissions.
• Analyze how herbivore stress alters plant volatile emissions and subsequent SOA production.
• Quantify the impact of terpene complexity on SOA mass yields compared to simplified models.

Main Methods:

• Characterized SOA generation from real Scots pine emissions under varying conditions.
• Utilized an herbivore stress treatment to modify plant volatile organic compound profiles.
• Employed a box model approach to estimate aerosol enhancement factors.

Main Results:

• Herbivore stress increased monoterpene and sesquiterpene emissions but decreased SOA mass yields.
• Sesquiterpenes controlled SOA mass yields in healthy plants; specific monoterpenes dominated in stressed plants.
• Accounting for terpene complexity led to a 1.5- to 2.3-fold aerosol enhancement compared to using α-pinene alone.

Conclusions:

• Simplifying terpene complexity in SOA models can lead to underpredictions of aerosol mass.
• Real plant emissions and their response to stress are critical for accurate climate impact assessments.
• Future SOA models must incorporate greater chemical detail to reflect atmospheric reality.