Novel quantitative method of reactive losses of ambient VOCs coupling chemical transport model simulation with receptor measurement

Abstract

Traditional photochemical age-based parameterization method (PAPM) exhibits substantial uncertainties in accurately quantifying the reactive losses of ambient volatile organic compounds (VOCs). PAPM primarily accounts for chemical reactions with hydroxyl radicals (•OH) and encounters inherent challenges in reliably estimating the photochemical age of VOCs. Thus, a novel quantitative method was developed for estimating VOC reactive losses by coupling chemical transport model (CTM) simulation with field measurement. This method fully considered the varying reaction ages of VOCs derived from different sources and incorporated multiple reaction pathways, thereby enabling the quantitative estimation of nighttime VOC losses. Results showed that VOC losses estimated using PAPM exceeded those calculated by CTM method (CTMM) by 11.9 %, 81.9 %, and 369 % during the daytime across three pollution cases. The estimated VOC losses obtained using CTMM were comparable between daytime (average of 37.5 ppbv) and nighttime (41.9 ppbv) across the three cases. Accurate quantification of reactive losses offers a more detailed description of the reactive loss processes, thereby enhancing the understanding of both the qualitative and quantitative aspects of secondary pollutant formation. Quantifying source contributions to VOC losses provides an effective basis for O₃ and secondary organic aerosol source apportionment, facilitating the development of targeted pollution control strategies.