Improved provincial emission inventory and speciation profiles of anthropogenic non-methane volatile organic compounds: a case study for Jiangsu, China
Other literature type
(issn: 1680-7324, eissn: 1680-7324)
Non-methane volatile organic compounds (NMVOC) are the key precursors of ozone (O<sub>3</sub>) and secondary organic aerosol (SOA) formation. Accurate estimation in their emissions plays a crucial role in air quality simulation and policy making. We developed a high-resolution anthropogenic NMVOCs emission inventory for Jiangsu in eastern China from 2005 to 2014, based on detailed information of individual local sources and the field measurements on source profiles of chemical industry. Totally 56 NMVOCs samples were collected in 9 chemical plants, and then analyzed with a gas chromatography-mass spectrometry system (GC-MS). Source profiles of stack emissions from synthetic rubber, acetate fiber, polyether, vinyl acetate, and ethylene production, and those of fugitive emissions from ethylene, butanol and octanol, propylene epoxide, polyethylene and glycol production were obtained. Various manufacturing technologies and raw materials lead to discrepancies in source profiles between our domestic field tests and foreign results for synthetic rubber and ethylene production. The provincial NMVOC emissions were calculated to increase from 1774 Gg in 2005 to 2507 Gg in 2014, and relatively large emission densities were found in cities along the Yangtze River with developed economy and industry. The estimates were larger than those from most other available inventories, due mainly to the complete inclusion of emission sources and to the elevated activity levels from plant-by-plant investigation in this work. Industrial processes and solvent use were the largest contributing sectors, and their emissions were estimated to increase respectively from 461 to 958 and from 38 to 966 Gg. Alkanes, aromatics and oxygenated VOCs (OVOCs) were the most important species, accounting for 25.9 %–29.9 %, 20.8 %–23.2 % and 18.2 %–21.0 % to annual total emissions respectively. Quantified with a Monte-Carlo simulation, the uncertainties of annual NMVOCs emissions vary slightly from years, and the result for 2014 was −41 % ~ +93 %, expressed as 95 % confidence intervals (CI). Reduced uncertainty was achieved compared to previous national and regional inventories, attributed mainly to the detailed classification of emission sources and to the use of information at plant level in this work. Discrepancies in emission estimation were explored for chemical and refinery sector with various data sources and methods. Compared with Multi-resolution Emission Inventory for China (MEIC), the spatial distribution of emissions in this work were more influenced by the locations of large point sources, and smaller emissions were found in urban region for developed cities in southern Jiangsu. Besides, clear discrepancies were found between this work and MEIC in the speciation of NMVOC emissions under the atmospheric chemistry mechanisms CB05 and SAPRC99. The difference of species OLE1 resulted mainly from the updated source profile of building paint use, and the differences of other species from the varied sector contributions to emissions of the two inventories. CMAQ simulation was applied to evaluate the two inventories, and better performance (indicated by daily 1h-max O<sub>3</sub> concentrations in Nanjing city) was found for January, April and October 2012 when the provincial inventory was used.