Quantitative and time-resolved nanoparticle composition measurements during new particle formation.

Area of Science:

• Atmospheric Chemistry
• Aerosol Science
• Environmental Science

Background:

• New Particle Formation (NPF) is a significant source of atmospheric nanoparticles.
• Understanding nanoparticle chemical composition is crucial for climate and air quality research.
• Existing models inadequately explain the incorporation of nitrogen and carbon into growing nanoparticles.

Purpose of the Study:

• To quantitatively measure the elemental composition of 20 nm diameter nanoparticles during NPF events.
• To differentiate chemical species associated with early versus late particle growth.
• To investigate the role of inorganic and organic species in nanoparticle formation and growth.

Main Methods:

• Utilized the Nano Aerosol Mass Spectrometer (NAMS) for high time-resolution measurements.
• Analyzed nanoparticle chemical composition in a rural/coastal environment.
• Correlated chemical composition changes with aerosol mass, number concentration, and particle size.

Main Results:

• Nanoparticle composition is dynamic on both NPF and non-NPF days.
• During NPF, sulfur and nitrogen incorporation are linked to gas-phase sulfuric acid and nitrogen-based growth processes.
• Newly formed particles are hygroscopic, while particles on non-NPF days are less so.

Conclusions:

• Sulfuric acid condensation drives early NPF, with subsequent nitrogen incorporation indicating neutralization and further growth.
• Carbonaceous matter is abundant, but inorganic species are preferentially enhanced during NPF.
• Current models need refinement to explain nitrogen and carbon incorporation into nanoparticles.