Intermediate-Volatility Organic Compounds (IVOCs) Emissions Based on Source-Specific Emission Ratios Relative to NonMethane Volatile Organic Compounds (NMVOCs) Give Better Representation of the Spatial Distribution of IVOCs in China

Abstract

Intermediate-volatility organic compounds (IVOCs) and their contribution to secondary organic aerosols (SOA) in China are simulated in GEOS-Chem with seven newly constructed IVOCs emission inventories (IEIs). The IEIs based on different references and source-specific emission ratios show a large range of emissions in China (4.8–14 Tg yr⁻¹) and also significant differences in major sources and spatial distributions. Among them, the IEI relative to nonMethane volatile organic compounds (NMVOCs) with a total emission of 12 Tg yr⁻¹, dominated by solvent use, better captures observed spatial distributions of IVOCs and SOA. In contrast, IEIs relative to primary organic aerosols (POA) misinterpret the major sources and tend to have a negative bias in megacities even when the total emission is scaled up to 14 Tg yr⁻¹. The study indicates that previous studies have underestimated IVOCs emission and hence the contribution to SOA. It also demonstrates the importance of using an appropriate reference to better represent the major sources and the spatial distribution of IVOCs.