Low-Wind/High Particulate Matter Episodes in the Calexico/Mexicali Region 1 The University of Utah 2 Universidad Autónoma de Baja California 3 San Diego

Low-Wind/High Particulate Matter Episodes in the Low-Wind/High Particulate Matter Episodes in the Calexico/Mexicali RegionCalexico/Mexicali Region

K.E. Kelly1, I.C. Jaramillo1, M. Quintero-Núñez2, K. Collins3, H.L.C. Meuzelaar1, J.Villar2,,C. Gonzalez2, M. Bejarano3, D. Wagner2, and J.S. Lighty1

11 The University of UtahThe University of Utah 2 2 Universidad Autónoma de Baja California Universidad Autónoma de Baja California

3 3 San Diego State University, Imperial Valley San Diego State University, Imperial Valley

Axel Schönbucher: Essen-Duisburg


ObjectivesObjectives

• Determine the frequency and severity of short-term PM episodes in the Imperial/Mexicali Valley.

• Identify the significant organic species in PM10

samples.

• Determine if PM10 composition varies significantly during high-wind/high PM episodes as compared to low-wind/high PM episodes.

• Perform a preliminary attribution of PM10 to its major organic source contributions.


Study LocationsStudy Locations


Dichot Sampler: PM10 Quartz

Source Attribution of PM

Dichot Sampler: PM10 Teflon

Environmental Enclosure

Switch Switch

DusTrak

Sampling SetupSampling Setup


Filter #2 (Jan 17 - 18)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.816

:31

17:0

6

17:4

0

18:1

5

18:5

0

19:2

4

19:5

9

20:3

3

21:0

8

21:4

2

22:1

7

22:5

2

23:2

6

0:01

0:35

1:10

1:45

2:19

2:54

3:28

4:03

4:37

5:12

5:47

6:21

6:56

7:30

8:05

8:40

9:14

9:49

10:2

3

10:5

8

11:3

2

12:0

7

12:4

2

13:1

6

Time

PM

10 (

mg/

m3)

0

0.5

1

1.5

2

2.5

3

3.5

4

Win

dspe

ed (

mph

)

PM Wind

Filter sample

PMPM1010 Hourly Example CalexicoHourly Example Calexico

DusTrack, and windspeed data from January 17-18 2006. DusTrack, and windspeed data from January 17-18 2006.


Summary of FiltersSummary of Filters

• A total of 31 sets of filters collected plus 4 blanks (25 used) from Winter 2006 and 5 filters from June 2004.

• Analyzed all filters for organics and selected filters for inorganics.

• All GC/MS chromatograms show similar chemistry.

• Winter filters - alkanes, alkanoic acids, PAHs, terpenoids, esters, benzaldehydes, and heteroaromatic compounds: butoxyethoxyethanol and quinoline.


Hourly average PM2.5 concentrations and windspeed during December, January, and

February (2004-2006), Ethel St. monitoring station, California Air Resources Board.

CARB PMCARB PM2.52.5 Hourly Winter DataHourly Winter Data


Hourly average PM2.5 concentrations and windspeed during June, July, and August (2004-2006), Ethel St. monitoring station, California Air Resources Board.

CARB PMCARB PM2.52.5 Hourly Summer DataHourly Summer Data


Count of hours during the winter (December, January, and February) and summer (June, July, and August) that exceed PM2.5 concentration of 35 μg/m3 from the California Air

Resources Board, Ethel St. monitoring station, Calexico, CA for the years 2004 - 2006.

CARB PMCARB PM2.52.5 Hours Exceeding 35Hours Exceeding 35g/mg/m33


Receptor samples• 31 PM10 Calexico/Mexicali samples collected in winter 2006 (25

used)• 5 PM10 evening samples collected during June 2004

PMPM1010 Source AttributionSource Attribution

Attribution techniques• Reduced compounds to 42• Principal component analysis (PCA)/ principal component regression

(PCR)• Positive matrix factorization (PMF)• Examined correlation coefficients between the reference source

profiles and the PCA/PCR and PMF results

Source profiles• Literature profiles – 19 with 169 compounds for vehicle emissions,

road dust, meat cooking, wood burning, and natural gas combustion• Local profiles – 7 with 90 organic compounds for agricultural burning

of wheat and canola (Imperial Valley) and trash burning (El Paso)


Total Calexico - Winter

Total Mexicali- Winter

PMF Results – All Samples PMF Results – All Samples


Comparison of the relative contribution results produced by PCR for both the average U.S (Calexico) and Mexican (Mexicali) receptor samples.

Total Calexico - Winter

Total Mexicali- Winter

PCRPCR Results – All SamplesResults – All Samples


Comparison of the relative contribution results produced by PCR for the average of five Calexico receptor samples, collected during June 2004.

PCRPCR Results – Summer SamplesResults – Summer Samples


ConclusionsConclusions

• Low-wind/high PM episodes are relatively common during winter months.

• These episodes are responsible for a large portion of the daily PM mass and can involve PM10 concentrations that exceed 500 g/m3 and PM spikes of hundreds of

g/m3.

•The organic analyses of the filters show that all of the wintertime samples regardless of wind conditions tended have similar organic composition, suggesting that the PM episodes are due to meteorological phenomena.

•In both Calexico and Mexicali, vehicle emissions (41.1-62.1%), biomass burning (14.1-26.4%), trash burning (16.6-24.1%) and road dust emissions (12.3-14.4%) tended to be the predominant organic sources contributing to the ambient PM concentrations.

•PM contributions estimated by PMF and PCR were comparable.

•The summer samples indicated a larger contribution from agricultural burns and no contributions from the home-heating sources (wood burning and natural gas) than found in the winter samples.


This work was sponsored by the Southwest Consortium for Environmental Research and Policy (SCERP) through a cooperative agreement with the U.S. Environmental Protection Agency. SCERP can be contacted for further information through www.scerp.org and [email protected].

Thanks to Cristina Jaramillo, one of the co-authors, who helped with this presentation, performed the GC/MS analysis, and source attribution.

AcknowledgmentsAcknowledgments

mailto:[email protected]

Documents

Low-Wind/High Particulate Matter Episodes in the Calexico/Mexicali Region 1 The University of Utah 2 Universidad Autónoma de Baja California 3 San Diego