Charlotte-Rock Hill-Gastonia MSA Summertime Ozone Formation - PowerPoint PPT Presentation

charlotte rock hill gastonia msa summertime ozone formation n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Charlotte-Rock Hill-Gastonia MSA Summertime Ozone Formation PowerPoint Presentation
Download Presentation
Charlotte-Rock Hill-Gastonia MSA Summertime Ozone Formation

Loading in 2 Seconds...

play fullscreen
1 / 15
Charlotte-Rock Hill-Gastonia MSA Summertime Ozone Formation
106 Views
Download Presentation
afra
Download Presentation

Charlotte-Rock Hill-Gastonia MSA Summertime Ozone Formation

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Charlotte-Rock Hill-Gastonia MSA Summertime Ozone Formation Photos from 2001 Mecklenburg Country State of the Environment Report

  2. Arizona’s Valley of the Sun “Brown Cloud” Phoenix photo from http://phoenix.about.com/library/weekly/uc051601a.htm, accessed Mar 2004 • Observed since early 1990’s; contains C Particles and NO2 (brown) gas • From burning fossil fuels: cars, construction equipment, power plants, lawn mowers, leaf blowers contribute to this brown cloud • Weather also a key factor

  3. Image take from http://www.al.noaa.gov/WWWHD/Pubdocs/TropoRural.html, accessed Mar 2004

  4. Presence of NO2 (brown gas) results in inevitable formation of ozone NO2 (brown) + sunlite  NO• + O• O• + O2 O3 (Ozone) • Control measures to effectively address ground-level ozone must focus on minimizing NO2 formation

  5. Ozone precursors • Nitrogen Oxides • Dry Air is 78% Nitrogen (N2), 21% Oxygen (O2) • Heating air to high temperatures forms NO• (motor vehicles, fossil-fuel power plants, lightning) • NO• is an ozone precursor and also reacts directly with ozone to destroy it • Volatile Organic Compounds (VOC’s) • VOC’s continuously emitted by fuel spills, motor vehicles, trees, air fresheners, paints, and countless other sources • OH• hydroxyl radical is the atmosphere’s “natural detergent” that cleans VOC’s from the air by initiating the process that converts them into carbon dioxide and water

  6. Volatile Organic Compound (VOC) Removal • Air’s natural VOC cleanser produced from ozone and water • Ozone (O3) + UV-B -> O2+ *O• • *O• + H2O  2OH• • OH• works by transforming stable VOC molecules (R-H) into reactive radicals (R•) • OH• + R-H  R• + H2O • Reactive organic radicals immediately combine with oxygen to form peroxide radicals • R• + O2 (R-O-O•)

  7. Formation of Nitrogen Dioxide • NO• + R-O-O•  NO2• + RO• • Formation of NO2 (and O3) driven primarily by: • Concentration of VOC’s (near emission sources) • Concentration of NO• (rural & downwind areas) • Concentrations of both NO• and VOC’s • ***Summertime ozone pollution results from an overload in our air of NO•, VOC’s, or both

  8. NO and VOC Effects on Ozone Production Both NO• + VOC Sensitive VOC Sensitive Region NO• Sensitive Region Both NO• + VOC Sensitive Figure from : http://www-personal.engin.umich.edu/~sillman/ozone.htm, accessed Mar 2004

  9. ’95-’99 AM NMOC/NOy Ratios for the Plaza Monitoring Site 20 NO Limited x 15 y 10 NMOC/NO VOC Limited 5 0 1994 1995 1996 1997 1998 1999 2000 From Perry, JL and Owens, PM, “Weekday/Weekend Variability and Long-Term Trends in Traffic, CO, NOy, and Ozone for the Charlotte Metropolitan Area during the 1990's, AWMA, June 2001

  10. I-77 Traffic Volume vs. Time of Day 5000 4000 3000 Hourly Volume 2000 1000 0 Time of Day (Hour) Sun Mon Tues Wed Thu Fri Sat From Perry and Owens, AWMA, 2001

  11. May-Sep ‘95-‘98 Plaza Average Hourly NOy 40 35 y 30 25 Concentration (ppb) Avg Hourly NO 20 15 10 5 1 3 5 7 9 11 13 15 17 19 21 23 Time of Day Sunday Monday Tuesday Wednesday Thursday Friday Saturday From Perry and Owens, AWMA, 2001

  12. 1990-1998 May-Sep Diurnal Charlotte Ozone Averages By Day of Week (weekend days-lines, weekdays-markers From Perry and Owens, AWMA, 2001

  13. Obtained from John White, NC DAQ

  14. From: http://www.epa.gov/airnow/showmaps.html?/airnow/2000/20000601/8p-ncsc.gif, accessed Mar 2004

  15. From: http://www.epa.gov/airnow/showmaps.html?/airnow/2000/20000601/8p-ncsc.gif, accessed Mar 2004