Contributions of local and regional sources of NOₓ to ozone concentrations in Southeast Texas

• Published in: Atmospheric environment (1994) Vol. 45; no. 17; pp. 2877 - 2887
• Main Authors: Zhang, Hongliang, Ying, Qi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2011; Elsevier
• Subjects: Air quality; Applied sciences; atmospheric chemistry; Atmospheric pollution; Atmospherics; Coal; coasts; Combustion; diesel engines; emissions; Emissions control; Exact sciences and technology; gasoline; Highways; Industrial areas; natural gas; ozone; Pollution; Regional; Texas; United States; North America; America; ASW, USA, Texas; USA, Texas, Houston; Harbor; CMAQ; Pollution control; Nitrogen compounds; Combustion; Identification; Motor vehicle; Urban area; Modeling; Coastal zone; Transport process; Rural area; Pollution abatement; Background ozone; Nitrogen oxide; Highway; Diesel engine; Ozone; Air quality; Source apportionment; Spatial distribution; Gasoline; Pollution source inventory; TexAQS 2000; Air pollution; Road traffic; Industrial area
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2011.02.047

The Community Multi-scale Air Quality (CMAQ) model with a modified SAPRC-99 photochemical mechanism was used to investigate the contributions of local and upwind NOₓ sources to O₃ concentrations in Southeast Texas during the 2000 Texas Air Quality Study (TexAQS 2000) from August 25 to September 5, 2000. Contributions from eight different local NOₓ source types and eight different source regions to the 8-h average daytime O₃ concentrations from 1100 to 1800 CST (referred to as AD O₃ hereafter) are determined. Both diesel engines and highway gasoline vehicles account for 25 ppb of AD O₃ in the urban Houston area. NOₓ from natural gas combustion produces 35 ppb of AD O₃ in the industrial area of Houston. Contributions from industrial sources and coal combustion to AD O₃ have comparatively less broad spatial distribution with maximum values of 14 ppb and 20 ppb, respectively. Although the local sources are the most important sources, upwind sources have non-negligible influences (20–50%) on AD O₃ in the entire domain, with a maximum of 50 ppb in rural and coastal areas and 20 ppb in urban and industrial areas. To probe the origins of upwind sources contributions, NOₓ emissions in the entire eastern United States are divided into eight different regions and their contributions to O₃ concentrations in the Houston–Galveston–Brazoria (HGB) and Beaumont–Port Arthur (BPA) areas are determined. Among the various NOₓ source regions resolved in this study, other Texas counties near the HGB and BPA areas and southeastern states are the most important non-local sources of O₃. Under favorable transport conditions, emissions from neighbor states and northeastern states could also contribute to non-negligible O₃ concentrations (7–15%) in the HGB and BPA areas. This indicates that in addition to reduce local emissions, regional NOₓ emission controls, especially from the neighbor counties and states, are also necessary to improve O₃ air quality in Southeast Texas.