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Stephen Mueller & Jonathan Mallard Tennessee Valley Authority

Stephen Mueller & Jonathan Mallard Tennessee Valley Authority. Modeling Natural Fine Particle Concentrations Using the CMAQ Model with Added Treatments of Reduced Sulfur Compounds. Identify natural emissions not routinely considered by US regulatory modeling.

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Stephen Mueller & Jonathan Mallard Tennessee Valley Authority

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  1. Stephen Mueller & Jonathan Mallard Tennessee Valley Authority Modeling Natural Fine Particle Concentrations Using the CMAQ Model with Added Treatments of Reduced Sulfur Compounds

  2. Identify natural emissions not routinely considered by US regulatory modeling. • Develop expanded natural emissions data base. • Identify model changes needed to accommodate expanded list of natural emissions. • Quantify effects of revised emissions/model versus results from “standard” modeling approach. Research on Natural Particle Levels

  3. US EPA lowered the 24-hr PM2.5 standard & is considering a lower annual standard. US Regional Haze Rule explicitly requires consideration of “natural haze” components. Efforts to establish secondary standards (e.g., SOx/NOx) should consider natural pollutants. Motivation for Research

  4. Current Technology • Biogenic VOCs • Biogenic NOx • Fires • Windblown dust • Sea salt • Animal ammonia • Geogenic SO2* • Added • Lightning NOx • Reduced sulfur (marine, wetlands, soil, lakes & geothermal ) • Ocean chlorinated gases • Ocean ammonia Natural Emissions *Not typically included in data inventories although the system is designed to include it.

  5. Study Area – Modeling Domain Limit of optimal lightning detection

  6. Dimethylsulfide (DMS): oceans, lakes, coastal wetlands. H2S: oceans, lakes, coastal wetlands, geothermal features (hot springs, fumaroles, etc.) Nitryl chloride (ClNO2) & HCl: oceans – these emissions are surrogates for complex interaction between air pollutants & sea salt. New Natural Emissions Species

  7. Natural & Anthropogenic Emissions in July 2002 Data Base “Orange”=anthropogenic “Green”=natural

  8. Gas chemistry • Added reactions involving DMS, H2S and derivatives. • Added ClNO2, HCl and chlorine radical reactions to CB05. • Cloud chemistry • Added reactions involving chlorine, OH, & DMS and its derivatives. CMAQ* Model CB05 Updates *Version 4.6

  9. Grid-Averaged Time Series: Sulfur

  10. Grid-Averaged Time Series: Aerosols

  11. Maximum Simulated “Natural” 24-hr Aerosol Concentrations for 2002 Sulfate Organic Carbon

  12. Simulated Particles vs. Haze Guidance

  13. Distribution of Simulated Natural + Background PM2.5 at 50 Receptors

  14. CMAQ natural particle simulations useful tool for investigating contributions of natural systems to PM2.5/haze, ozone and deposition. • EPA natural haze guidance is too simplistic. • Modeling DMS & H2S introduces competition for OH that reduces sulfate formation in natural systems…effects in combined emissions simulations? Primary Conclusions

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