aerosol composition at a rural site southeast of london measured by high resolution mass...
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Aerosol composition at a rural site southeast of London measured by high resolution mass spectrometry
Lu Xu
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ClearfLo (Clean Air for London) Project
• collaborative multidisciplinary project to study boundary layer pollution across London
detling
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Data collection
• Good data: 1/18/2012 to 2/14/2102 (27 days)• Bypass and Thermal Denuder
Thermal Denuder
valveinlet AMS
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AMS
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Bypass data: time series
16
14
12
10
8
6
4
2
0
µg
/m3
1/21/2012 1/25/2012 1/29/2012 2/2/2012 2/6/2012 2/10/2012 2/14/2012Date and Time
From East(highest loading,very high nitrate)
From ocean (cleanest air mass)
Average loading:4.88 mg/m3
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Bypass data: Average mass spectra
1.5
1.0
0.5
0.0Nit
rate
eq
uiv
alen
t m
ass
(µg
m-3
)
100908070605040302010m/z
MSSD Org +1.5586 MSSD NO3 +1.7910 MSSD SO4 +0.7878 MSSD NH4 +0.8409 MSSD Chl +0.1129
0.25
0.20
0.15
0.10
0.05
0.00Nit
rate
eq
uiv
ale
nt
mas
s (
µg
m-3
)
100908070605040302010m/z
MSSD Org +1.5586
Org44/Org = 0.12(O/C = 0.54, Aiken et al, 2008)
NH+(16)NH+(17)
NO+(30) NO2+(46)
CO+(28) CO2+(44)
COOH→CO+ and CO2+BBOA: 0.3 – 0.4HOA: 0.06 – 0.1
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Deconvolution of organics spectraT
ime
= + +
x
Con
trib
utio
n (u
g/m
3 ), S
ourc
e 1
Mass Spectrum,Source 1
x
Con
trib
utio
n (u
g/m
3 ), S
ourc
e 2
Mass Spectrum,Source 2
x
Con
trib
utio
n (u
g/m
3 ), S
ourc
e 3
Mass Spectrum,Source 3
Mass Spectrum
+ …. . .
Positive Matrix Factorization (PMF) (Lanz et al., 2007; Ulbrich et al., 2009)
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0.5 0.4 0.2 0.99+ + =
Characteristic nose and eye
Characteristic ear Characteristic mouse
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UMR three factor solution
OOA: correlates better with nitrateHOA: correlates with COBBOA: fresh OA, correlates with CH3CN
21% 37%
42%
Oxygenated organic aerosol (OOA)
Biomass burning orangic aerosol (BBOA)
Hydrocarbon-like organic aerosol (HOA)
C2H4O2+(60) C3H5O2+(73)
OOA
HOA
BBOA
SOABiomass burning
POA
OOA is surrogate for SOAHOA is surrogate for POA
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Bypass vs. denuded data
86420
1/21/2012 1/25/2012 1/29/2012 2/2/2012 2/6/2012 2/10/2012 2/14/2012dat
1612
840543210
Load
ing
(g/
m3)
6
4
2
0
1.5
1.0
0.5
0.0
Org
NO3
SO4
NH4
Chl
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Different TD temperature
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Summary
• Cleanest air mass comes from the ocean• Air mass from the East : characterized by high
loadings, especially high nitrate• PMF resolved three factors: HOA, OOA, BBOA• Nitrate and ammonia are more volatile
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Future work
• High resolution analysis • Thermal denuder data• Comparison with other measurements at the
Detling site as well as other sites (especially London site)
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AcknowledgementKn
owle
dge
age
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Please Don’t Ask……
QUESTIONS?