understanding air toxics and carbonyl pollutant sources in
TRANSCRIPT
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Understanding Air Toxics and Understanding Air Toxics and
Carbonyl Pollutant Sources in Carbonyl Pollutant Sources in
Boulder County, ColoradoBoulder County, Colorado
A. Eisele1,2, M. Hannigan1, J. Milford1, D. Helmig2, P. Milmoe3, D. Tanner2
1Department of Mechanical Engineering, University of Colorado, Boulder, CO 80309-0427
2Institute of Arctic & Alpine Research, University of Colorado, Boulder, CO 80309-0450
3Boulder County Public Health, Environmental Health Division, Boulder, CO 80304-1824
Presented by: Presented by:
Pam Milmoe & Adam EiselePam Milmoe & Adam Eisele
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DISCLAIMERDISCLAIMER
• The contents of this presentation reflect the views of the contractor, who is responsible for the accuracy of the data presented herein. The contents do not necessarily reflect the views of the U.S. Environmental Protection Agency.
• This presentation does not constitute a standard, specification, or regulation. The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein only because they are considered essential to the object of this document.
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RoadmapRoadmap
• Motivation
• Project Objectives
• Quality Assurance
• Data Analysis
• Source Apportionment
• Modeling Results
• Conclusions
• Recommendations
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MotivationMotivation
• Anderson Study in 1996 found higher aldehyde concentrations in Boulder than Denver
• Oil & natural gas production activities in neighboring counties increased and began to pose potential health risks
• Denver Metro Area (DMA) experiences high ozone concentrations and is currently designated as non-attainment for failing to meet the 8-hr ozone NAAQS set by the EPA
(www.colorado.edu)
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Successful PartnershipsSuccessful Partnerships
• BCPH, University of Colorado, & EPA Region
8 collaborated to form project team that collected one year of detailed air toxics measurements
• A number of students were trained & educated on measuring air quality; two of which now work at EPA
• Public Health staff gained valuable monitoring knowledge and experience and
provided valuable information to residents
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Boulder County Public Health Boulder County Public Health
Air Toxics WebsiteAir Toxics Website
http://www.bouldercounty.org/health/environ/airquality/outdoorair/airToxics.htm
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DMA NFR Nonattainment AreaDMA NFR Nonattainment Area
(EPA Region 8, 2004)
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5 Sampling Locations5 Sampling Locations
Niwot RidgeNiwot Ridge
LongmontLongmontLyonsLyons
BoulderBoulder
South BoulderSouth BoulderDenverDenver
(2008 Google Maps)
Oil & GasOil & Gas
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Adjacent Oil & Gas ActivitiesAdjacent Oil & Gas Activities
Existing PermitsExisting Permits Pending PermitsPending Permits
(COGCC, 2008)
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ProjectProject ObjectivesObjectives
• Delineate concentrations of local scale
VOCs, carbonyls, & ozone
• Develop a baseline reference for longer-term measuring
• Evaluate and improve ambient air quality exposure & community-scale dispersion models
• Aid in air quality management strategies in Boulder County & Denver DMA NAA
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What Did We Do?What Did We Do?
• VOCs (27)
• Carbonyls (8)
InIn--Situ MeasurementsSitu Measurements
• Ozone
• Meteorological Data
24hr integrated sample every 6th
day @ each location
Eight consecutive 3hr samples
every 6th day @ one location
SamplingSampling
continuous, 5 minute avg
Mar 1, 2007 Mar 1, 2007 –– Feb 24, 2008Feb 24, 2008
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Air Toxics MonitoredAir Toxics Monitored
• VOCs (EPA Method TO-15)
– benzene, toluene, ethylbenzene, xylenes,
hexane, & styrene
• Carbonyls (EPA Method TO-11A)
– formaldehyde, acetaldehyde, & acrolein
• Ozone (40 CFR, Part 50 App. D)
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Sampling InstrumentationSampling Instrumentation
OzoneOzone CarbonylsCarbonyls
VOCsVOCs
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Overall Data CompletenessOverall Data Completeness
VOCs
~85%
Carbonyls
~94%
Ozone
~95%
Includes 3Includes 3--hour and 24hour and 24--hour sampleshour samples
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Percent of Samples DetectedPercent of Samples Detected
Carbonyls VOCs
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2424--hr VOC Duplicateshr VOC Duplicates
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2424--hr Carbonyl Duplicateshr Carbonyl Duplicates
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Eight 3Eight 3--hr samples vs. 24hr samples vs. 24--hr hr
samplessamples
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Seasonal Averages: Seasonal Averages: VOCsVOCs
24hr Seasonal VOC Averages: All Sites
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
Mixing R
atio (ppbv)
n-butane
toluene
m&p-xylene
BO LY NR SBLO
Each dot represents a season, starting with spring
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2424--hr nhr n--butanebutane
Overall, VOC concentrations were not seasonally dependent
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24hr Seasonal Carbonyl Averages: All Sites
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
Mix
ing
Ra
tio
(p
pb
v)
formaldehyde
acetaldehyde
acetone
Seasonal Averages: Seasonal Averages: CarbonylsCarbonyls
BO LO LY NR SB
Each dot represents a season, starting with spring
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2424--hr Formaldehydehr Formaldehyde
Carbonyl concentrations were greatest in summer months
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Eight 3Eight 3--hr vs. 24hr vs. 24--hr hr
Formaldehyde: LongmontFormaldehyde: Longmont
The sum of the eight 3-hr samples compared fairly well to the one 24-hr sample collected during the same period
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Ozone Correlation MatrixOzone Correlation Matrix
10.490.780.690.72South Boulder
10.410.370.34Niwot Ridge
10.710.77Lyons
10.62Longmont
1Boulder
SouthBoulder
Niwot Ridge
LyonsLongmontBoulder
Correlation Matrix: 1-hr Ozone Values
The Niwot Ridge background site had the lowest correlation values when compared to the Front Range sites
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Seasonal 1Seasonal 1--hr Ozone hr Ozone
AveragesAverages
Seasonal variations at Boulder & Niwot Ridge
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Weekend vs. Weekday Weekend vs. Weekday
AnalysisAnalysis
• Compared weekend
vs. weekday samples for VOCs, carbonyls, and ozone to better understand the
impact of mobile source traffic
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Weekend vs. Weekday OzoneWeekend vs. Weekday Ozone
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1996 & 1999 EPA NATA1996 & 1999 EPA NATA
for Formaldehydefor Formaldehyde
2007-2008 Boulder County Median: 1.50 1.50 µµg/mg/m33
(www.epa.gov/nata/mapconc.html)
1996 NATA: 0.61–0.85 µg/m3 1999 NATA: 1.22-1.51 µg/m3
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DDEH 05DDEH 05--06 vs. BCPH 0706 vs. BCPH 07--0808
Overall, BCPH values were less than the Denver Study
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CDPHE 2006 Summer StudyCDPHE 2006 Summer Study
BCPH values were also less than the 2006 CDPHE data
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Source ApportionmentSource Apportionment
• Pairwise correlation analysis
• Principal Components Analysis (PCA)
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2424--hr Carbonyl Correlation hr Carbonyl Correlation
Matrix: Boulder SiteMatrix: Boulder Site
Low correlation values were likely a quantification issue
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2424--hr VOCs Correlation hr VOCs Correlation
Matrix: Boulder SiteMatrix: Boulder Site
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Acetaldehyde vs. Acetaldehyde vs.
FormaldehydeFormaldehyde
Acetaldehyde & formaldehyde correlated well at all sites
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nn--pentane vs. npentane vs. n--butanebutane
Strong VOC correlations suggest similar emission sources
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Source ProfilesSource Profiles
(Lin et al., 1994)
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Potential Pollution Source Potential Pollution Source
Based on PCA ResultsBased on PCA Results(based on variance)(based on variance)
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Dispersion ModelingDispersion Modeling
• AERMOD & MOBILE6.2 models used
• Pollutants included in model
– Formaldehyde
– Acetaldehyde
– BTEX
– Hexane
– Diesel PM
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Predicted 2006 nPredicted 2006 n--butane with 2007 butane with 2007
Boulder Observed nBoulder Observed n--butane (ppbV)butane (ppbV)
Inventories underpredict n-butane direct emissions
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Dispersion Model ResultsDispersion Model Results
Site
Obs
Butane
avg
AERMOD
Butane avg
Obs
Pentane
avg
AERMOD
Pentane
avg
Obs
Hexane
avg
AERMOD
Hexane
avg
Boulder Fire Station 2.95 0.002 1.35 <.001 0.71 0.04
Longmont 4.48 0.09 1.66 0.02 0.62 0.01
Lyons 1.24 0.001 0.46 <.001 0.21 0.005
South Boulder 1.20 0.001 0.44 <.001 0.21 0.005
• AERMOD generally under predicts by a
factor of 2–10 in Denver-Boulder Region
• Using local/rural met measurements would improve modeled results
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Photochemical ModelingPhotochemical Modeling
• OZIPR model used to model formation of ozone and secondary pollutants
• Run from May - August 2007 with observed data
• Overall, OZIPR generally overpredicted acetaldehyde concentrations by a factor of 3
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Ozone July 23, 2007
0
0.02
0.04
0.06
0.08
0.1
600 800 1000 1200 1400 1600 1800
Hours
Ozo
ne
(p
pm
)
Model Lyons
Comparison of OZIPR Predictions Comparison of OZIPR Predictions
& Observed Ozone at Lyons, CO& Observed Ozone at Lyons, CO
Ozone was simulated reasonably well on most days
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Formaldehyde July 23, 2007
0
1
2
3
4
5
6
7
8
600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800
Time (MDT)
HC
HO
(p
pb
)
Lyons Model A Model B
Comparison of OZIPR Predictions & Comparison of OZIPR Predictions &
Observed Formaldehyde at Lyons, COObserved Formaldehyde at Lyons, CO
Formaldehyde predictions were much closer for Model B
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SummarySummary
• Delineate concentrations of local scale air toxics
• Develop a baseline reference for longer-term measuring
• Evaluate and improve air quality exposure and dispersion models
• Guide air quality management strategies in Boulder County & DMA NAA
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ConclusionsConclusions
• Overall carbonyl & VOC concentrations in 07-08 were lower than those in the Anderson Studies and other FR studies
• Carbonyl concentrations peaked in the summer months, suggesting increased photochemistry
• VOC concentrations were relatively stable and were not seasonably variable
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ConclusionsConclusions
• From PCA results, mobile source exhaust, natural gas condensate emissions, and meteorology are significant pollution source
• Ozone values varied from site to site, but increased significantly in summer
• Ozone values occasionally exceeded the former/current 8-hr NAAQS values
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RecommendationsRecommendations
• Increase sampling frequency for weekend vs. weekday analyses
• Use higher resolution sampling durations for source apportionment
• Use analytical equipment capable of quantifying additional natural gas markers
• Get EPA assistance with AQS uploads
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AcknowledgementsAcknowledgements
• Boulder County Public Health, Colorado Dept. of Public Health, & EPA Region 8
• Jana Milford, Mike Hannigan, & Detlev Helmig
• Steve Dutton, Greg Brinkman, David Tanner, Ian Hoffecker, Boulder Fire Rescue, Foothills Baptist Church, Gordon Pierce, Duane Kitzis, Gregg Thomas, Ken Distler, Michael Copeland, Jacques Heuber, Molly Brodin, & Larry Anderson
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ReferencesReferences
• Anderson, L.G., Lanning, J.A., Barrell, R., Miyagishma, J., Jones, R.H., Wolfe, P., 1996. Sources and sinks of formaldehyde and acetaldehyde: An analysis of Denver’s Ambient Concentration Data. Atmospheric Environment 30, 2113-2123.
• Anderson, L.G., Machoved, C.M., Lanning, J.A., 1998. Effects of the Mandated High Oxygen Fuels Program on the Concentrations of Formaldehyde and Acetaldehyde in Denver’s Air. Proc Air Waste Man Ass. Paper No 98-WA61A.01, 4 pp.
• Lin, C., Milford, J.B., 1994. Decay-Adjusted Chemical Mass Balance Receptor Modeling for Volatile Organic Compounds. Atmospheric Environment 28, 3261-3276.
• Mobile-Source Air Toxics: A Critical Review of the Literature on Exposure and Health Effects: Special Report 16. Health Effects Institute, November 7, 2007.
• 1996 NATA, http://www.epa.gov/ttn/atw/natamain/index.html. August 13, 2008.
• 1999 NATA, http://www.epa.gov/ttn/atw/natamain/index.html. August 13, 2008.
• Riggs, S.D., Anderson, L.G., Lanning, J.A., 1996. A Comparison of Source Contributions to Carbonyl Concentrations in Denver, Colorado and Outlying Areas. Proc. Air Waste Man. Ass. Paper No.97-WP68B.02, 11 pp.
• Thomas, G.W., Bain D., Williams, S.M., 2007. Going One Step Beyond: A Neighborhood Scale Air Toxics Assessment in North Denver. Prepared for Federal Highway Administration NCHRP program. Report available fall 2007 at: www.denvergov.org/EAP
• Thomas, G.W., 2004. The Denver Urban Air Toxics Assessment: Methodology, Results, Risks. Report available at: www.denvergov.org/EAP