Effect of Removal of Power Plant Emissions on the characteristics of Ozone Concentration Changes in Summer

In this study, the changes in ozone (O-3) concentrations due to the removal of power plant emissions were analyzed using a community multi-scale air quality (CMAQ) model. Two different CMAQ model simulations, one considering the emissions from the Hadong power plant and one without considering the emissions, were conducted to investigate the effect of the emissions on the changes in the O-3 concentrations in the surrounding areas. Subsequently, the CMAQ simulations exhibited an increase in the O-3 concentration (25.24%) despite a decrease in the NOx (-18.87%) and volatile organic carbon (VOC, -11.27%) concentrations, which are major O-3 precursors. The changes in the NO and O-3 concentrations due to the removal of power plant emissions presented a strong negative correlation (r= -0.72). This indicated that the increase in the O-3 concentration was mainly attributed to the significantly decreased NO concentration, thus, mitigating the O-3 titration reaction (NO+O-3 -> NO2+ O-2). Additionally, due to the VOC-limited (i.e., NOx-saturated) conditions in the study region, NO affected the O-3 concentration, indicating that the O-3 concentrations in a particular region are not only proportional to the increase or decrease in emissions. Therefore, an in-depth understanding of the chemical O-3 production and loss in a particular region is necessary to accurately evaluate the effect of emission control on the changes in the O-3 concentration.