Measurement report: Size-resolved particle effective density measured by an AAC-SMPS and implications for chemical composition
<p>The effective density (<span class="inline-formula"><i>ρ</i><sub>eff</sub></span>) is closely associated with the aging process and can serve as a tracer of chemical composition. Recently, studies investigating the effect of particle size on den...
Saved in:
| Main Authors: | , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-05-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/4755/2025/acp-25-4755-2025.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | <p>The effective density (<span class="inline-formula"><i>ρ</i><sub>eff</sub></span>) is closely associated with the aging process and can serve as a tracer of chemical composition. Recently, studies investigating the effect of particle size on density have been limited. In this study, size-resolved <span class="inline-formula"><i>ρ</i><sub>eff</sub></span> was characterized using a tandem aerodynamic aerosol classifier (AAC) and scanning mobility particle sizer (SMPS) system during 1 month of observations in Hangzhou. The results indicate that the <span class="inline-formula"><i>ρ</i><sub>eff</sub></span> values of the particles exhibit a unimodal distribution, with average values ranging from 1.47 to 1.63 g cm<span class="inline-formula"><sup>−3</sup></span>, increasing as the particle diameter increases. The diurnal variation is more pronounced for small particles (<span class="inline-formula"><i>d</i><sub>ae</sub></span> <span class="inline-formula"><i><</i></span> 350 nm), which generally exhibit lower density during the day and higher density at night. The relationship between <span class="inline-formula"><i>ρ</i><sub>eff</sub></span> and particle diameter varies under different pollution conditions due to differences in the chemical composition of the particles. The SHapley Additive exPlanations (SHAP) values revealed good relationships between <span class="inline-formula"><i>ρ</i><sub>eff</sub></span> and the bulk composition of particles with diameters smaller than 350 nm, while the relationship with larger particles was weak. As determining the size-resolved chemical composition of particles remains challenging, a new method to investigate the size-resolved chemical composition was proposed, in which the size-resolved composition can be derived from the <span class="inline-formula"><i>ρ</i><sub>eff</sub></span> and fixed material density of secondary inorganic aerosols (SIAs), organic aerosols (OAs), and black carbon (BC).</p> |
|---|---|
| ISSN: | 1680-7316 1680-7324 |