Traffic Related Emissions of Radical Precursors HCHO and HONO in Los Angeles During CalNex

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.

`



– 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.

`




– However, this knowledge is needed to further refine and validate air quality modeling.

– Primary goal: HCHO/CO, HONO/CO (CO: traffic marker)

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Measurements

CalNex Pasadena Site

Measurements



Measurements



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

SSES

SSW

SW

WSW

W

WNW

NW

NNW

v > 0.2 m/s

[ppb]

0

100

200

300

400N

NNE

NE

ENE

E

ESE

SE

SSES

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

SSES

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

SSES

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

SSES

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

SSES

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

SSES

SSW

SW

WSW

W

WNW

NW

NNW

v > 0.2 m/s

[ppt]

0

500

1000

1500

2000N

NNE

NE

ENE

E

ESE

SE

SSES

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


Evening

Noon

MorningNoonEvening

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?





– 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





– 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

Traffic Related Emissions of Radical Precursors HCHO and HONO in Los Angeles During CalNex

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