Upload
quanda
View
17
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Molecular Characterization of Organic Aerosols from the Los Angeles Ground Site during the CalNex 2010 Campaign Using High-Resolution Mass Spectrometry. Laskin, J. Laskin , P. Roach, B. Heath PNNL. T. Nguyen, N. Levac , D. Bones, A. Bateman, S. Nizkorodov University of California, Irvine. - PowerPoint PPT Presentation
Citation preview
Molecular Characterization of Organic Aerosols from the Los Angeles Ground Site during the
CalNex 2010 Campaign Using High-Resolution Mass Spectrometry
T. Nguyen, N. Levac, D. Bones, A. Bateman, S. NizkorodovUniversity of California, Irvine
A. Laskin, J. Laskin, P. Roach, B. HeathPNNL
Specific Objective: Nitrogen Containing Organic Compounds
• Ubiquitous in atmospheric aerosol, yet poorly characterized on a molecular level
• May contributed to adverse health effects of particulate matter
• May absorb visible light and contribute to “brown carbon” aerosol
Conventional "Brown Carbon"• HULIS from biomass burning• Organic light-absorbing material from vehicular
emissionsAndreae, Gelencser, Atmos. Chem. Phys. 2006 Jacobson J. Geophys. Res. 1999
"Brown Carbon" from SOA Aging
Fresh SOA: scatters light; COOLS the surface
NH3 or amines
Aged SOA: absorbs light; WARMS the surface
• Known to contain hetero-N compounds• Both biogenic and anthropogenic SOA undergo this type of aging
Laboratory Studies (e.g. Bones et al, JGR 2010; Laskin J, et al Anal.Chem. 2010; Nakayama et al, JGR2010; De Haan et al, EST 2011)
Field Observations: Mexico city (Roach, et al Anal.Chem. 2010), Shanghai (Wang et al, EST 2010)
PILS (Particle-Into-Liquid Sampler)Particles collected straight in water30 min per sample
Types of Samples Collected
Substrates for SEM/EDX, X-ray spectro-microscopy, and Ice Nucleation studies
MOUDI Cascade Impactor
Particles collected on Teflon and Al foil substrates6-hours per set of size segregated samples0-6 am; 6 am - noon; noon -6 pm; 6 pm - midnight
PILS
High-Res.MS
Optical Microscopy of Heterogeneous Ice Nucleation
Bingbing Wang Dr. Daniel Knopf
Poster 38
Advantages of High Resolution MS
Analysis of OA Using Nano-DESI MS
Routine analysis of <10 ng OA Probe size <100 mm
Promising Days for the HR-MS AnalysisAMS data from P. Hayes, J. Jimenez et al. (U. Colorado)
June 5: unusually large “ amine OA" signal in the morning
Nano DESI HR-MS
0 200 400 600 800 1000 12000
1x104
2x104
3x104
4x104
5x104
6x104
inte
nsity
, arb
. uni
ts
m/z
June 5 IB-6
200 400 600 800 1000 12000.0
5.0x103
1.0x104
1.5x104
2.0x104
2.5x104
3.0x104
3.5x104
4.0x104
inte
nsity
, arb
. uni
ts
m/z
June 5 IIA-6
200 400 600 800 1000 12000
1x104
2x104
3x104
4x104
5x104
inte
nsity
, arb
. uni
ts
m/z
June 5 IIIB-6
200 400 600 800 1000 12000
1x104
2x104
3x104
4x104
5x104
inte
nsity
, arb
. uni
ts
m/z
June 5 IVA-6
200 400 600 800 1000 12000.0
5.0x104
1.0x105
1.5x105
2.0x105
inte
nsity
, arb
. uni
ts
m/z
June 6 IIB-6
LVOOALVOOA
SVOOA
SVOOA
~40% peaks assigned
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
100 300 500 700 900
LVOOA and SVOOA are Chemically Related
C15H26O -(CH2)x H+
C16H30O3 -(CH2)x H+
C20H36O4 -(CH2)x H+
C38H64O6-(CH2)x H+
KMCH2, Da
KMD CH
2
(sample 6:00-12:00) LVOOA
SVOOA
0.0 0.1 0.2 0.3 0.4 0.5 0.60.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35fra
ctio
n
O/C
June 5 IB-6
0.0 0.1 0.2 0.3 0.4 0.5 0.60.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
fract
ion
O/C
June 5 IIa-6
0.0 0.1 0.2 0.3 0.4 0.5 0.60.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
fract
ion
O/C
June 5 IIIA-6
0.0 0.1 0.2 0.3 0.4 0.5 0.60.0
0.1
0.2
0.3
fract
ion
O/C
June 5 IVA-6
O/C Histograms
0:00-6:00 6:00-12:00
12:00-18:00 18:00-24:00
CxHyNz fresh emissions..?
0.0 0.1 0.2 0.3 0.4 0.5 0.60.0
0.1
0.2
0.3
0.4
0.5
0.6
fract
ion
N/C
June 5 IB-6
0.0 0.1 0.2 0.3 0.4 0.5 0.60.0
0.1
0.2
0.3
0.4
0.5
0.6
fract
ion
N/C
June 5 IB-6
0.0 0.1 0.2 0.3 0.4 0.5 0.60.0
0.1
0.2
0.3
0.4
0.5
0.6
fract
ion
N/C
June 5 IB-6
0.0 0.1 0.2 0.3 0.4 0.5 0.60.0
0.1
0.2
0.3
0.4
0.5
0.6
fract
ion
N/C
June 5 IB-6
N/C Histograms
0:00-6:00 6:00-12:00
12:00-18:00 18:00-24:00
CxHyNz
N-Organics in CARES samples (DOE 2010 field study)
Photos: S. Springston R. Zaveri
Sacramento, T0 site
Nanospray DESI – Line Scan Analysis
Nanospray DESI – Line Scan Analysis
200 300 400 500 600
1x103
2x103
3x103
4x103
5x103
6x103
7x103
inte
nsity
, arb
. uni
ts
m/z
CxHyN1CxHyN2
5
7
9
11
13
15
17
19
21
23
25
150 200 250 300 350 400 450 500 550
N1 speciesN2 speciesN>3 species
DBE
m/z
or
C16H11N1
Brown C Event
• CxHyNz – organics are ubiquitous in urban OAPossible Sources:
25% of identified peaks are:aliphatic CxHyN1, CxHyOzN1
- Amines
• CxHyN1 – are also observed at the Bakersfield site(R. Sellon, A. Goldstein, et al - Poster 31)
Intensive Road Construction Activity at the Time of CxHyNz
Episode (field notes of R. Zaveri) oFumes of Asphaltenes …?oEmissions from Vehicles with Catalytical Converters
…?
Outlook: PILS vs DESI: June 5, 12-6 pm
Very different subsets of compounds detected by two methods
Multiply Charged Ions in PILS Spectra (M-Ca2+, M-Mg2+, …)
Time Series of WSOC Detected by PILS
SUMMARY• Molecular-level HR-MS analysis provides critical
information for interpretation of the OA types, their chemistry
• Essential to assist with more detailed classification
• Outlook: Closure studies with the OA optical properties data indicative of “brown carbon”Closure studies with the gas phase, VOC data focused on chemistry of SOA formation and aging