Emission of intermediate volatile organic compounds from animal dung and coal combustion and its contribution to secondary organic aerosol formation in Qinghai-Tibet Plateau, China

Abstract

Intermediate volatility organic compounds (IVOCs) are important precursors to secondary organic aerosols (SOAs), but are often neglected in studies concerning SOA formation. This study addresses the significant issue of IVOCs emissions in the Qinghai-Tibetan Plateau (QTP), where solid fuels are extensively used under incomplete combustion conditions for residential heating and cooking. Our field measurement data revealed emission factor of the total IVOCs (EF_IVOCs) ranging from 1.56±0.03 to 9.97±3.22 g/kg from various combustion scenarios in QTP. The markedly higher EF_IVOCs in QTP than plain regions can be attributed to oxygen-deficient conditions. IVOCs were dominated by gaseous phase emissions, and the primary contributors of gaseous and particulate phases IVOCs are the unresolved complex mixture and alkanes, respectively. Total IVOCs emissions during the heating and non-heating season in QTP were estimated to be 31.7±13.8 and 6.87±0.45 Gg, respectively. The estimated SOA production resulted from combined emissions of IVOCs and VOCs is nearly five times higher than that derived from VOCs alone. Results from this study emphasized the pivotal role of IVOCs emissions in air pollution and provided a foundation for compiling emission inventories related to solid fuel combustion and developing pollution prevention strategies.