STUDY OF SOURCE ATTRIBUTION OF UNSATURATED HYDROCARBONS FOR OZONE PRODUCTION IN THE HOUSTON-GALVESTON AREA WITH THE EXTENDED SAPRC99 CHEMICAL MECHANISM Beata Czader Daewon W. Byun Department of Chemistry & Institute for Multidimensional Air Quality Studies (IMAQS)

Propylene (Ton/Day) Motivation The metropolitan area of Houston is home to the largest grouping of petrochemical industrial plants in the United States billion pounds of ethylene produced – 52% of national capacity 10.9 billion pounds of propylene produced – 63% of national capacity TexAQS 2000 demonstrated the importance of HRVOC for ozone formation especially ethylene, propylene, 1,3-butadiene, and other butenes

OBJECTIVES Improve the resolution of the chemical mechanism – SAPRC99ext mechanism Develop emission processing scheme for SAPRC99ext Study the relationship between measured formaldehyde spikes and alkene emissions Study the differences in reactivity obtained with different chemical mechanisms Compare AQM simulations based on different emissions inventories APPROACH

SAPRC99 and SAPRC99ext emission lumping Speciation profiles SAPRC99SAPRC99ext ETHENE OLE1 OLE2 PROPENE BUTADIENE13 OLE1 OLE2 Gipson, G. L.: Speciation in Models-3/MEPPS and Models-3/SMOKE. 2001

Reactions implemented in the SAPRC99ext mechanism PROPENE + OH, O 3, NO 3, O( 3 P)BUTADIENE13 + OH, O 3, NO 3, O( 3 P) Source: Carter, W., Documentation of the SAPRC-99 chemical mechanism for VOC reactivity assessment. OLE1 → 73.2 (SAPRC99) → 85.0 (SAPRC99ext) OLE2 → 75.8 (SAPRC99) → 77.0 (SAPRC99ext) Molecular Weight Source: Carter, W., 2000, Programs and Files Implementing the SAPRC-99 Mechanism and its Associated Emissions Processing Procedures for Models-3 and Other Regional Models. Carter, W., 2004, Documentation of speciation preprocessor programs for SMOKE. R1R2SAPRC99SAPRC99ext Propene/Butadiene OLE1OH 32.3* * * OLE2OH 63.1* * * Reaction constant k(T)=A exp(-E/RT) at 298 K (cm 3 · molec -1 · s -1 )

Modeling Data and Methodology 1. NEI 1999, SAPRC99, 2. NEI 1999, SAPRC99ext 3. NEI 1999, CB-4 4. TEI 2000 (base4a.pto2n2), SAPRC99 5. TEI 2000 (base4a.pto2n2), SAPRC99ext 6. TEI 2000 (base4a.pto2n2), CB-4 Simulated episode: Aug. 23 – Aug. 31, 2000  SMOKE 1.4  CMAQ 4.2.2

The comparison of emissions for SAPRC-99 and SAPRC-99 extended SAPRC99SAPRC99 extSAPRC99SAPRC99 ext

Emission rates with SAPRC99 and SAPRC99ext  National Emission Inventory NEI, 1999  Texas Emission Inventory TEI, 2000, base4a.pto2n2 (IMPUTED) TEI, OLE1 NEI, OLE1 TEI, OLE1-PROPENE NEI, OLE1-PROPENE TEI, PROPENE NEI, PROPENE

Process Analysis results with SAPRC99ext TEI NEI TEI

CMAQ simulation results for ozone SAPRC99SAPRC99ext NEI TEI

Comparison of simulation results with observed data (at the surface) La Porte side HCHO O3O3

Williams Tower HCHO data for HRM-3 obtained from P. K. Dasgupta HRM-3

Clinton

Preliminary Conclusions  Among the anthropogenic emissions ethene and propene contribute most to formaldehyde production. The contribution of 1,3-Butadiene and other olefins is not significant.  With TEI, simulated concentrations of ethylene, propylene and other olefins are higher than observed values, at the surface.  With NEI, olefin concentrations match observed values for some days of the episode and are much lower for other (Aug. 23, 24, and 25).  Simulated values of 1,3-Butadiene match measured values at the surface, with both TEI and NEI.  The differences in ozone production between SAPRC99 and SAPRC99ext are around 1 ppb, as expected, however extending the SAPRC99 mechanism helps to identify the source-receptor relationship better.