Traffic Related Emissions ofTraffic Related Emissions ofRadical Precursors HCHO and HONORadical Precursors HCHO and HONO
in Los Angeles During CalNexin Los Angeles During CalNex
S. Alvarez1, B. Rappenglück1, P.R. Veres2,3, J.M. Roberts2, A.K. Cochran4, C. Afif5,6, V. Michoud5, J.F. Doussin5, A. Borbon5, H. Osthoff7
(1) Department of Earth and Atmospheric Sciences, University of Houston, TX/USA(2) NOAA Earth System Research Laboratory, Boulder, CO/USA
(3) Max-Planck Institut für Chemie, Mainz, Germany(4) North Carolina Agricultural and Technical State University, Greensboro, NC/USA
(5) LISA, UMR-CNRS 7583, Université Paris Est Créteil, Université Paris Diderot, Créteil, France(6) Department of Chemistry, Faculty of Science, Saint Joseph University, Beirut, Lebanon
(7) University of Calgary, Canada
• early morning
• midmorning
• afternoon
HCHO + UV HCO + H < 334 μm H + O2 + M HO2 + M HCO + O2 CO + HO2 NO + HO2 NO2 + OH
nm
HONO + UV OH + NO < 400 μm
nm
O3 + UV O(1D) + O2 < 310 nm O(1D) + H2O 2OH
– Sources of OH
– Secondary formation through photochemical breakdown of anthropogenic and biogenic VOCs.
– Primary emission through incomplete combustion. Potential sources:• mobile sources (traffic exhaust)• point sources (in petrochemical production).
Formation of Formaldehyde (HCHO)Formation of Formaldehyde (HCHO)
– Gas phase • NO + OH → HONO
– Heterogeneous formation • 2NO2 + H2O → HONO + HNO3
• Photo-enhanced heterogeneous reactions
– Primary emission through combustion processes
Formation of Nitrous Acid (HONO)Formation of Nitrous Acid (HONO)
Traffic Related Emissions of HONO and HCHOTraffic Related Emissions of HONO and HCHO
– So far only scarce traffic emissions data is available which includes both compounds.
`
Traffic Related Emissions of HONO and HCHOTraffic Related Emissions of HONO and HCHO
– So far only scarce traffic emissions data is available which includes both compounds.
– In particular for HONO traffic related data was obtained more than a decade ago.- mostly in Europe- tunnel measurements (heavy duty vehicles?)
`
Traffic Related Emissions of HONO and HCHOTraffic Related Emissions of HONO and HCHO
– So far only scarce traffic emissions data is available which includes both compounds.
– In particular for HONO traffic related data was obtained more than a decade ago.- mostly in Europe- tunnel measurements (heavy duty vehicles?)
– However, this knowledge is needed to further refine and validate air quality modeling.
`
Traffic Related Emissions of HONO and HCHOTraffic Related Emissions of HONO and HCHO
– So far only scarce traffic emissions data is available which includes both compounds.
– In particular for HONO traffic related data was obtained more than a decade ago.- mostly in Europe- tunnel measurements (heavy duty vehicles?)
– However, this knowledge is needed to further refine and validate air quality modeling.
– Primary goal: HCHO/CO, HONO/CO (CO: traffic marker)
`
Measurements
CalNex Pasadena Site
Measurements
CalNex Pasadena Site
CalNex Pasadena Site
Measurements
CalNex Pasadena Site
CalNex Pasadena Site
Parameter Method
CO Vacuum ultraviolet (VUV) Fluorescence; AL5001
PAN CIMS, (GC)
HCHO Hantzsch/ Fluorescence; AL4021
HONO SA:NED derivization/ HPLC; NitroMAC
0
100
200
300
400N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
v > 0.2 m/s
[ppb]
0
100
200
300
400N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
v > 0.2 m/s
[ppb]
Day (6 am – 8 pm) Night (8 pm – 6 am)
CO
NightDay
0
200
400
600
800
1000N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
v > 0.2 m/s
[ppb]
0
200
400
600
800
1000N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
v > 0.2 m/s
[ppb]
Night
Day (6 am – 8 pm) Night (8 pm – 6 am)
PAN
Day
0.0
0.5
1.0
1.5
2.0N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
v > 0.2 m/s
[ppb]
0.0
0.5
1.0
1.5
2.0N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
v > 0.2 m/s
[ppb]
Night
Day (6 am – 8 pm) Night (8 pm – 6 am)
HCHO
Day
0
500
1000
1500
2000N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
v > 0.2 m/s
[ppt]
0
500
1000
1500
2000N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
v > 0.2 m/s
[ppt]
Night
Day (6 am – 8 pm) Night (8 pm – 6 am)
HONO
Day
Morning rush hour Evening rush hour
Morning
Morning rush hour
MorningNoon
Morning rush hour
Noon
MorningNoon
Morning rush hour Evening rush hour
Evening
Noon
MorningNoonEvening
MorningNoonEvening
MorningNoonEvening
Morning rush hour Evening rush hour
MorningEvening
4:30-6:00 am 8:00-10:00 pm
Time frames taken for correlation analysis
4:30-6:00 am(PAN < 300 ppt)
HCHO vs CO (weekdays)
4:30-6:00 am(PAN < 300 ppt)
HCHO vs CO (weekdays)
4:30-6:00 am and 8:00-10:00 pm(PAN < 300 ppt)
4:30-6:00 am(PAN < 300 ppt)
HCHO vs CO (weekdays)
4:30-6:00 am and 8:00-10:00 pm(PAN < 300 ppt)
(i) weekdays(ii) rush hour time 5:00-9:00 am(iii) global radiation < 10 Wm-2
(iv) PAN < 50 ppt(v) no precipitation(vi) RH > 80%
Comparison: Houston/TXHighway Junction 07/15-10/15/09
y = 2.66(±0.13) – 140.0(±45.3)R2=0.75
y = 2.98(±0.13) + 484.5(±46.1)R2=0.69
CalNex-Pasadena “higher”CalNex-Pasadena “higher”
4:30-6:00 am(PAN < 300 ppt)
HONO vs CO (weekdays)
4:30-6:00 am(PAN < 300 ppt)
HONO vs CO (weekdays)
4:30-6:00 am and 8:00-10:00 pm(PAN < 300 ppt)
4:30-6:00 am(PAN < 300 ppt)
(i) weekdays(ii) rush hour time 5:00-9:00 am(iii) global radiation < 10 Wm-2
(iv) PAN < 50 ppt(v) no precipitation(vi) RH > 80%
Comparison: Houston/TXHighway Junction 07/15-10/15/09
y = 2.66(±0.13) – 140.0(±45.3)R2=0.75
HONO vs CO (weekdays)
4:30-6:00 am and 8:00-10:00 pm(PAN < 300 ppt)
CalNex-Pasadena “higher”CalNex-Pasadena “higher”
– HCHO and HONO traffic related emissions during CalNex;preliminary results:
• Increase of HCHO and HONO during rush hour(s)
• HCHO <> CO ratio: slope around 3.5 - 4.9 pptv HCHO/ 1 ppbv CO• HONO <> CO ratio: slope around 3.3 - 4.2 pptv HONO/ 1 ppbv CO
• Higher than in roadside study in Houston But: in Houston: PAN < 50 ppt; in CalNex-Pasadena: PAN < 300 ppt)- CalNex-Pasadena: more aged air masses?- Traffic composition? - Traffic flow?
– HCHO and HONO traffic related emissions during CalNex;preliminary results:
• Increase of HCHO and HONO during rush hour(s)
• HCHO <> CO ratio: slope around 3.5 - 4.9 pptv HCHO/ 1 ppbv CO• HONO <> CO ratio: slope around 3.3 - 4.2 pptv HONO/ 1 ppbv CO
• Higher than in roadside study in Houston But: in Houston: PAN < 50 ppt; in CalNex-Pasadena: PAN < 300 ppt)- CalNex-Pasadena: more aged air masses?- Traffic composition? - Traffic flow?
– What next?
• HONO: final QA, inclusion of additional HONO data (NOAA)• PAN: filling gaps in PAN data (GC?)• Merging with VOC and NOx data• Source apportionment• Comparison with MOBILE6 / MOVES2010 traffic emissions modeling
– HCHO and HONO traffic related emissions during CalNex;preliminary results:
• Increase of HCHO and HONO during rush hour(s)
• HCHO <> CO ratio: slope around 3.5 - 4.9 pptv HCHO/ 1 ppbv CO• HONO <> CO ratio: slope around 3.3 - 4.2 pptv HONO/ 1 ppbv CO
• Higher than in roadside study in Houston But: in Houston: PAN < 50 ppt; in CalNex-Pasadena: PAN < 300 ppt)- CalNex-Pasadena: more aged air masses?- Traffic composition? - Traffic flow?
– What next?
• HONO: final QA, inclusion of additional HONO data (NOAA)• PAN: filling gaps in PAN data (GC?)• Merging with VOC and NOx data• Source apportionment• Comparison with MOBILE6 / MOVES2010 traffic emissions modeling
Acknowledgements: - NOAA: Roberts et al., Borbon et al., Osthoff- JJJ: Alvarez, Rappenglück
weekendweekend
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