How pollution chemistry builds isoprene SOA in Alabama
At Birmingham in SOAS 2013, IEPOX tracers dominate isoprene SOA and correlate with sulfate and ozone, pointing to anthropogenic enhancement of biogenic aerosol.
Source
Assessing the impact of anthropogenic pollution on isoprene-derived secondary organic aerosol formation in PM<sub>2.5</sub> collected from the Birmingham, Alabama, ground site during the 2013 Southern Oxidant and Aerosol Study
Study at a glance
- Design
- Other — SOAS 2013 filter campaign quantifying isoprene SOA tracers vs sulfate/ozone
- N
- N=120 · 120 high-volume PM2.5 filters from Birmingham, AL (1 Jun–16 Jul 2013)
- Population
- PM2.5 at Birmingham, Alabama during SOAS 2013
- Outcome
- Isoprene-derived SOA tracer mass and correlations with anthropogenic pollution markers
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
Authors quantified isoprene SOA tracers in 120 high-volume PM2.5 filters from Birmingham during 1 June–16 July 2013 using GC/EI-MS and UPLC/ESI-HR-QTOFMS, then correlated them with SEARCH gases, sulfate, and meteorology.
What they found
Isoprene SOA reached ~20% of OM (~7% average). IEPOX tracers were 92.45% of quantified isoprene SOA mass (2-methyltetrols 47%). Tracers correlated with sulfate and daytime ozone; most IEPOX SOA was likely formed upwind in forests, not locally at night.
The limits
What it doesn't show
Acidity was not limiting (mean pH 1.8); NOx gases did not correlate with tracers; urban ozone/nitrate cannot explain most of the SOA mass.
Key terms
- IEPOX
- Isoprene epoxydiols whose uptake yields 2-methyltetrols and related SOA.
- SOA
- Secondary organic aerosol formed from oxidized VOCs.
- MAE/HMML
- Methacrylic acid epoxide / hydroxymethyl-methyl-α-lactone high-NOx isoprene pathway.
- SOAS
- 2013 Southern Oxidant and Aerosol Study field campaign.
- 2-methyltetrols
- Major IEPOX-derived SOA tracers in southeastern US PM2.5.
Flashcards
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Quiz yourself
Isoprene SOA share of OM at BHM:
Common questions
Share of OM from isoprene SOA?
Up to ~20%, ~7% on average.
Dominant tracer family?
IEPOX-derived, 92.45% of quantified isoprene SOA.
Key anthropogenic partner?
Particulate sulfate (and ozone for some tracers).
Where did most IEPOX SOA form?
Upwind forested air, transported to Birmingham.
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