Constraining uncertainties in particle-wall deposition correction during SOA formation in chamber experiments
Autor: | Jeffrey R. Pierce, Renee C. McVay, Theodora Nah, Nga L. Ng, John H. Seinfeld |
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Jazyk: | angličtina |
Rok vydání: | 2017 |
Předmět: |
chemistry.chemical_classification
Atmospheric Science Correction method 010504 meteorology & atmospheric sciences Condensation Analytical chemistry 010501 environmental sciences Organic compound 01 natural sciences behavioral disciplines and activities lcsh:QC1-999 Aerosol lcsh:Chemistry Deposition (aerosol physics) chemistry lcsh:QD1-999 Particle High surface area Loss rate lcsh:Physics 0105 earth and related environmental sciences |
Zdroj: | Atmospheric Chemistry and Physics, Vol 17, Iss 3, Pp 2297-2310 (2017) |
Popis: | The effect of vapor-wall deposition on secondary organic aerosol (SOA) formation has gained significant attention; however, uncertainties in experimentally derived SOA mass yields due to uncertainties in particle-wall deposition remain. Different approaches have been used to correct for particle-wall deposition in SOA formation studies, each having its own set of assumptions in determining the particle-wall loss rate. In volatile and intermediate-volatility organic compound (VOC and IVOC) systems in which SOA formation is governed by kinetically limited growth, the effect of vapor-wall deposition on SOA mass yields can be constrained by using high surface area concentrations of seed aerosol to promote the condensation of SOA-forming vapors onto seed aerosol instead of the chamber walls. However, under such high seed aerosol levels, the presence of significant coagulation may complicate the particle-wall deposition correction. Here, we present a model framework that accounts for coagulation in chamber studies in which high seed aerosol surface area concentrations are used. For the α-pinene ozonolysis system, we find that after accounting for coagulation, SOA mass yields remain approximately constant when high seed aerosol surface area concentrations ( ≥ 8000 µm2 cm−3) are used, consistent with our prior study (Nah et al., 2016) showing that α-pinene ozonolysis SOA formation is governed by quasi-equilibrium growth. In addition, we systematically assess the uncertainties in the calculated SOA mass concentrations and yields between four different particle-wall loss correction methods over the series of α-pinene ozonolysis experiments. At low seed aerosol surface area concentrations (2 cm−3), the SOA mass yields at peak SOA growth obtained from the particle-wall loss correction methods agree within 14 %. However, at high seed aerosol surface area concentrations ( ≥ 8000 µm2 cm−3), the SOA mass yields at peak SOA growth obtained from different particle-wall loss correction methods can differ by as much as 58 %. These differences arise from assumptions made in the particle-wall loss correction regarding the first-order particle-wall loss rate. This study highlights the importance of accounting for particle-wall deposition accurately during SOA formation chamber experiments and assessing the uncertainties associated with the application of the particle-wall deposition correction method when comparing and using SOA mass yields measured in different studies. |
Databáze: | OpenAIRE |
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