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NARSTO Workshop on Innovative Methods for Emission Inventory Development and Evaluation University of Texas, Austin October 14-17, 2003 |
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Sensitivity of Urban Ozone Formation to Chlorine Emission Estimates
Sunghye Chang1, Elena McDonald-Buller1, Yosuke Kimura1, Greg Yarwood2, James Neece3,
Matthew Russell1, Paul Tanaka1, and David Allen1
1 Center for Energy and Environmental Resources
The University of Texas at Austin, Austin, TX 78758
2 ENVIRON International Corporation, Novato, CA 94945-5010
3 Texas Natural Resource Conservation Commission, Austin, TX 78753
Recent evidence has demonstrated that chlorine radical chemistry can enhance tropospheric VOC oxidation and has the potential to enhance ozone formation in urban areas. In order to investigate the regional impacts of chlorine chemistry in Southeastern Texas, preliminary estimates of atmospheric releases of atomic chlorine precursors from industrial point sources, cooling towers, water and wastewater treatment, swimming pools, tap water, reactions of chlorides in sea salt aerosols, and reactions of chlorinated organics were developed. To assess the potential implications of these estimated emissions on urban ozone formation, a series of photochemical modeling studies was conducted to examine the spatial and temporal sensitivity of ozone and a unique marker species for chlorine chemistry, 1-Chloro-3-methyl-3-butene-2-one (CMBO), to molecular chlorine emissions estimates. Based on current estimates of molecular chlorine emissions in Southeastern Texas, chlorine chemistry has the potential to enhance ozone mixing ratios by up to 11-16 ppbv. Impacts varied temporally, with emissions from cooling towers primarily responsible for a morning enhancement in ozone mixing ratios and emissions from residential swimming pools for an afternoon enhancement. Maximum enhancement in CMBO mixing ratios ranged from 59-69 pptv.