Abstract
Large industrial facilities, such as petrochemical complexes, have decisive effects on regional air quality: directly due to their own hazardous volatile organic compounds (VOCs) emissions and indirectly due to their contribution to secondary air pollution. In South Korea, pronounced ozone and particulate matter issues have been reported in industrial areas. In this study, we develop a new top-down VOC emission rate estimation method using in situ airborne formaldehyde (HCHO) observations in the downwind plume of the Daesan Petrochemical Complex (DPC) in South Korea during the 2016 Korea–United States Air Quality (KORUS-AQ) mission. On May 22, we observed a peak HCHO mole fraction of 12 ppb after a transport time of 2.5 h (distance approximately 36 km) under conditions where the HCHO photochemical lifetime was 1.8 h. Box model calculations indicate that this elevated HCHO is mainly due to secondary production (more than 90% after 2 h of plume aging) from various VOC precursors including ethene, propene, and 1,3-butadiene. We estimate a lower limit for yearly DPC VOC emissions of 31 (±8.7) × 103 MT/year for HCHO precursors and 53 (±15) × 103 MT/year for all measured primary VOCs. These estimates are 1.5–2.5 times higher than the latest Korean emission inventories, KORUSv5. This method is beneficial not only by tracking the sources, sinks, and evolution of HCHO but also by validating existing emission inventories.
Highlights
Large industrial facilities, such as petrochemical complexes, have decisive effects on regional air quality: directly due to their own hazardous volatile organic compounds (VOCs) emissions and indirectly due to their contribution to secondary air pollution
The VOCs emission inventories evaluated by this approach often have high variability among them and tend to be lower than those inferred from a top-down validation due to differences in emission factors (EFs) depending on the calculation methods (Ryerson et al, 2003; Kim et al, 2011; Lee et al, 2011; Fang et al, 2016; Li et al, 2017)
Previous studies have shown that observations of HCHO can provide constraints on VOC emissions and their impact on air quality. de Gouw et al (2015) showed an increasing HCHO mole fraction as a function of downwind distance from the third largest fuel ethanol refinery in the United States, suggesting that secondary HCHO production from VOC oxidation occurred in the plume
Summary
Environmental Assessment Group, Korea Environment Institute, Sejong, Republic of Korea. A top-down approach estimates an emission rate using aircraft and/or satellite observations in combination with inverse modeling to infer the flux information from trace gas measurements (Stavrakou et al, 2009; Fang et al, 2016). Taking advantage of the relationship between HCHO and its parent VOCs, in this study, we infer the amount of parent VOCs emissions from the observed HCHO mole fraction changes as HCHO forms in the downwind of the Daesan Petrochemical Complex (DPC) located on the Taean peninsula in South Korea at the edge of the Yellow Sea. Airborne in situ HCHO measurements of multiple plume crossings downwind, combined with a 0-D box model and information on the VOC speciation from the emitter, allows determination of HCHO production and loss terms in the plume and yields an estimate for the VOC emission rate from this source. The approach for estimating VOC emission rates presented here can be performed without simultaneous comprehensive airborne VOC measurements, if the source signatures of various VOCs are given by emission inventory and/or ground measurements, enabling more frequent and lower cost validation of emission inventories for regional air quality improvement
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
