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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 13, No. 1, 2016, pp. 209-220
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Bioline Code: st16020
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 13, No. 1, 2016, pp. 209-220
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Photochemical model simulations of air quality for Houston– Galveston–Brazoria area and analysis of ozone–NOx– hydrocarbon sensitivity
Kommalapati, R.R.; Liang, Z. & Huque, Z.
Abstract
As part of the State Implementation Plan for
the Houston–Galveston–Brazoria (HGB) area which has
been declared as a non-attainment area, it was required to
assess the impacts of pollutant emissions, meteorological
conditions, and initial and boundary conditions on air
quality. In this study, photochemical model simulations
using the Comprehensive Air Quality Model with extensions
(CAMx) were conducted for three ozone episodes
between May and October of 2006. The CAMx simulations
compared fairly well with the hourly average concentrations
of ozone measured at the monitoring sites, and the
index of agreement (IOA) values for all the three ozone
episodes were found greater than 0.65, which proved to be
good for CAMx model performance. Both simulated and
observed peak ozone concentrations were observed to
occur between 12:00 and 15:00 h. The CAMx simulation
results showed that there were 68 days where the maximum
8-h mean ozone concentrations exceeded the NAAQS
of 75 ppb out of a total of 72 days simulated in the three
ozone episodes. For all three episodes, ozone concentrations
were highest during the third quarter of the day. The
photochemical indicator ratios of hydrogen peroxide
(H2O2) to nitric acid (HNO3) ([H2O2]/[HNO3]) showed the
HGB area to be a nitrogen oxide (NOx)-sensitive regime
for the episodes studied. This indicated that volatile
organic compounds (VOCs) are plentiful, and NOx is the
limiting precursor for ozone formation in the HGB area.
The plentiful VOCs in this region are possibly produced
from industries and refineries in the HGB area.
Keywords
Air quality; CAMx; NOx; Ozone; Photochemical model; Sensitivity analysis; Simulations
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