applications of the pam oxidation flow reactor with aerosol mass...
TRANSCRIPT
Applications of the PAM oxidation flow reactor with aerosol mass spectrometry
Andy Lambe
AMS Users MeetingJanuary 20, 2021
1
PAM/OFR - General Approach
2
• Oxidants: OH, NO3, Cl, Br• Common applications: oxidative aging of ambient, vehicle, biomass emissions;
increasingly, with PMF • Slowik et al., ACP, 2012; Li et al., JGR-A, 2019
PAM - most common OFR (63)
3
Penn State Aerodyne
AERODYNE RESEARCH, Inc. 45 MANNING ROAD, BILLERICA, MA 01821 (978) 663 9500
www.aerodyne.com CACC_OPT_12_2
Potential Aerosol Mass
(PAM) Oxidation Flow
Reactor
A highly oxidizing environment that
simulates oxidation processes on
timescales of days in the atmosphere
in minutes in real time.
• Laboratory or fie
l
d st udi es of secondar y aer osol
generation via gas-phase hydroxyl (OH) radical
or ozone (O3) oxidation of gas-phase precursors.
• Heterogenous oxidation of primary aerosols.
• Compatible with gas and particle mass
spectrometry techniques.
• Complement to laboratory smog chamber
techniques commonly used to generate
secondary organic aerosol (SOA).
• Based on Penn State flo
w
react or desi gn int roduced
by Kang et al. (2007) and further evaluated by Lambe
et al. (2011).
• Field deployable.
• Wide range of oxidant exposure times attainable with
dimmable UV lamps (primary emission intensity at
λ = 254 nm) at high measurement throughput/
resolution.
• OH/HO2 and OH/O3 ratios similar to tropospheric
ratios. Amounts of OH, HO2, and O3 are 100 to
10,000 times larger than in the daytime troposphere,
simulating days of atmospheric oxidation in minutes.
APPLICATIONS ADVANTAGES
Typical setup for measurements incorporating PAM reactor. Control software facilitates data-
logging at 1 Hz and automated control with event sequencing for unattended operation (dashed
grey = analog input/output; dashed red = digital input/output)
Bill Brune, Penn State
• ~70% of PAM user groups also AMS/ACSM users• This is a fraction of total OFR user community
Aging BBOA
4
ToF-AMSMissoula, USA (FLAME-3)Ortega et al., ACP, 2013
Aging urban background air [1]
5
ToF-AMSSuwon, South KoreaPark et al., J. Korean Soc. Atmos. Environ, 2019
Aging urban background air [2]
6
ToF-AMSPasadena, USA (CalNEX)Ortega et al., ACP, 2016
• Transition from “functionalization” to “fragmentation”
Aging on-road vehicle emissions
7
ToF-ACSM
Beijing, China
Liao et al., ES&T, under review
Aging laboratory diesel emissions
8
SP-ToF-AMSTampere/Helsinki, FinlandKarjalainen et al., ES&T, 2019
Particulate organic nitrate generation
Q-/ToF-ACSM,ToF-AMSb-pinene + NO3 SOALambe et al., AMT, 2020
9
• Used to characterize instrument response to pON @ ACSM Intercomparison 2018 (ACMCC)
Resources
• Wiki: https://sites.google.com/site/pamwiki/• Includes Jose’s 2018 IAC tutorial
• Manual: https://pamusersmanual.jimdo.com/
10
Oxidative aging: HOA→SV-OOA →LV-OOA
11
Lambe et al., ACP, 2011
~1 day ~10 days
• PMF application to ambient/OFR-processed AMS data: Slowik et al., ACP, 2012; Li et al., JGR-A, 2019
Aging traffic tunnel emissions
12
Pittsburgh, USA
Tkacik et al., ES&T, 2014
• Positive secondary aerosol enhancements up to ~ 100 mg m-3 near sources• Transition from “functionalization” to “fragmentation”
Aging of rural background air masses
Skrehalla, Sweden
Ahlberg et al., Atmosphere, 2020
• Negative secondary aerosol enhancements due to fragmentation