1. Within-Week Variability and Long-Term Trends in Traffic, Power Plant Emissions, and Ambient CO, NO y and Ozone for the Charlotte Metropolitan Area Jennifer L. Perry* and Patrick M. Owens Department of Chemistry Winthrop University, Rock Hill, SC 29733 * Current address: Department of Chemistry, Duke University, Durham, NC 27708

2. 2 Objectives Show Charlotte regional growth by traffic volumes and power plant emissions Characterize trends in NO y, CO, Hydrocarbon, and Ozone monitoring data Understand how traffic and power plant emission fluctuations within each week affect pollutant levels

3. 3 Type of DataMonitoring SiteSelected Data Traffic Counts Interstate I-77 Jun-Aug, 1990-1997 South Blvd, Wilkinson Blvd, Graham St. May-Sep, 1990-1997 (8-9 AM, 6-7 PM, daily) Mecklenburg County Ambient Air Monitors Plaza, County Line O 3 : May-Sep, ’90-00 CO: May-Sep, ’93-00 NO y : May-Sep, ’95-00 Hydrocarbons, ’95-99 ArrowwoodO 3 : May-Sep, ’90-00 Power Plant Emission Monitors (CEM) Riverbend, Allen Marshall, Buck NO x : May-Sep, ’96-00

4. 4 Traffic Locations, Monitoring Sites, & Power Plants

5. 5 Regional NO x Sources 1997 Gaston County Power Plant Emissions 12,930 tons (Allen) 3,780 tons (Riverbend) 1996 Mecklenburg County Emissions 17,295 tons (mobile sources) 687 tons (stationary sources)

6. 6 Traffic Sites

7. 7 I-77 Traffic Volume vs. Time of Day 0 1000 2000 3000 4000 5000 Time of Day (Hour) Hourly Volume SunMonTuesWed ThuFriSat

8. 8 5 10 15 20 25 30 35 40 1357911131517192123 Time of Day Avg Hourly NO y Concentration (ppb) SundayMondayTuesdayWednesday ThursdayFridaySaturday May-Sep ‘95-‘98 Plaza Average Hourly NO y

9. 9 May-Sep ‘93-‘98 Plaza Average Hourly CO 200 300 400 500 600 700 800 900 1000 1357911131517192123 Time of Day (Hour) Avg. Hourly CO Reading (ppb) SundayMondayTuesdayWednesday ThursdayFridaySaturday

10. 10 1990-1998 May-Sep Diurnal Charlotte Ozone Averages By Day of Week (weekend days-lines, weekdays-markers

11. 11 Day of Week NO x Emissions from Four Coal-fired Plants near Charlotte -25 -20 -15 -10 -5 0 5 10 15 20 SunMonTueWedThuFriSat Day of Week % Difference from 7-Day Average Allen Riverbend Marshall Buck

12. 12 Coal-fired Power Plant Hourly NO x Emissions by Day of Week for a Recent Season 25.00 30.00 35.00 40.00 45.00 50.00 55.00 05101520 Hour of Day Daily Tons NO x Emissions Sun Mon Tue Wed Thu Fri Sat

13. 13 Day of Week Variation at Fontana Urban BTEX Sampling Site -0.15 -0.1 -0.05 0 0.05 0.1 0.15 Sun-ThuThu-SatSat-Sun Benzene Toluene m/p-Xylene I-77 Traffic Cts Day of Week Variation at Kennedy Urban BTEX Sampling Site -0.3 -0.2 -0.1 0 0.1 0.2 Sun-ThuThu-SatSat-Sun Fraction of Diff from 7-Day Avg Benzene Toluene m/p-Xylene I-77 Traffic Cts Day of Week Variation in Average Noon to Noon BTEX Levels in Charlotte Aug-Sep ’96 and May-Aug ’97 Day of Week Variation at Dilworth Urban BTEX Sampling Site -0.15 -0.1 -0.05 0 0.05 0.1 0.15 Sun-ThuThu-SatSat-Sun Benzene Toluene m/p-Xylene I-77 Traffic Cts

14. 14 Traffic Growth for I-77 and South Blvd Locations 0 500 1000 1500 2000 2500 3000 3500 4000 199019911992199319941995199619971998 Year Average Hour Traffic8:00 Traffic18:00 Traffic 0 1000 2000 3000 4000 5000 6000 19901991199219931994199519961997 Year

15. 15 7-9 AM Yearly NO y and CO Trends at County Line and Plaza (Gar ’00) Sites

16. 16 May-Sep Mecklenburg County Ozone Trends 0.04500 0.05000 0.05500 0.06000 0.06500 0.07000 0.07500 199019921994199619982000 Year County LineArrowwoodPlaza

17. 17 NO x Emission Trends from the two Coal-fired Power Plants, Allen and Riverbend, near Charlotte 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 JuneJulyAugJun-AugMay-Sep Avg Tons NO x / Day 1996 1997 1998 1999 2000

18. 18 Long-term Trends for Allen & RB NO x Emissions, Power, and Emissions per Unit of Power 3000.00 4000.00 5000.00 6000.00 7000.00 8000.00 9000.00 19961997199819992000 NO x emissions + GigaWatt-Hours 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Lbs NO x / Megawatt-hr Tons NOx emissionsGigaWatt-HoursLbs NOx/Mwt-hr

19. 19 ’95-’99 AM Hydrocarbon Reactivity-weighted Concentration Trends for the Plaza Site

20. 20 ’95-’99 AM NMOC/NO y Ratios for the Plaza Monitoring Site 0 5 10 15 20 1994199519961997199819992000 NMOC/NO y NO x Limited VOC Limited

21. 21 7-8 AM Within Week Fluctuations for NO y, CO and Traffic Data 0.2 0.4 0.6 0.8 1 1.2 1.4 SunMonTue-FriSat Reading / 7 Day Average NO y COTraffic

22. 22 May-Sep 1990-1998 Within Week Ozone Averages for the three Mecklenburg County Monitors 0.95 0.97 0.99 1.01 1.03 1.05 SunMonTue-FriSat Reading / 7 Day Average County LineArrowwoodPlaza

23. 23 DaysTrafficCONO y OzonePower NO x Su/Tu-Fr0000.33730 Mo/Tu-Fr0.74880.94730.03810.34840.0023 Sa/Tu-Fr00.001200.46830.0025 P-Values for Day of Week Comparisons of Traffic, Ambient Pollutants, and Power Plant NO x Emissions

24. 24 Conclusions AM CO and NO y ambient concentrations correlate well with observed traffic patterns Weekend AM levels much lower than weekdays Monday AM CO comparable to other weekdays Monday AM NO y lower than other weekdays Within week power plant NO x emissions Tues-Fri 10% above 7-day average Mon & Sat 7.5% below 7-day average Sun 19% below 7-day average Monday AM NO x lowest in week; low Monday AM NO y ambient levels may be due to this

25. 25 Conclusions Total Power Plant NO x emissions from Allen and Riverbend Power Plants are stable From 1996-2000, power generated during May-Sep by the two Gaston Co. plants increased 27%. From 1996-2000, NOx emissions per unit of power decreased 20%. From 1996-2000, total NO X emissions from Allen and Riverbend increased 4%.

26. 26 Conclusions Hydrocarbon Trends From 1997-1999, average AM Hydrocarbons levels at Plaza decreased The Charlotte metropolitan region appears to be a VOC-limited area 1995-1999 Plaza AM VOC/NO y ratios are primarily between four and eight. Ozone within week variation: Weekend ozone levels in Mecklenburg County are equivalent to weekday levels

27. 27 Recommendations For the city of Charlotte, implement ozone control measures that reduce ambient VOC levels Replace the use of ozone action days with practices to be implemented throughout ozone season Evaluate the use of total NO x emissions budgets for all power plants in the Charlotte region

28. 28 Acknowledgements North Carolina Division of Air Quality (Steve Few, Brian Timin) Winthrop University students (Gentry Ridgeway and Steve Hudson) City of Charlotte Department of Transportation (Charles Able) South Carolina Department of Transportation (Joe Boozer) Duke Energy (Buddy Davis and Kris Knudsen)