Improved provincial emission inventory and speciation profiles of anthropogenic non-methane volatile organic compounds: a case study for Jiangsu, China

摘要

Non-methane volatile organic compounds (NMVOCs) are the key precursors ofozone (O) and secondary organic aerosol (SOA) formation. Accurateestimation of their emissions plays a crucial role in air quality simulationand policy making. We developed a high-resolution anthropogenic NMVOCemission inventory for Jiangsu in eastern China from 2005 to 2014, based ondetailed information of individual local sources and field measurements ofsource profiles of the chemical industry. A total of 56 NMVOCs samples werecollected in nine chemical plants and were then analyzed with a gaschromatography – mass spectrometry system (GC-MS). Source profiles of stackemissions from synthetic rubber, acetate fiber, polyether, vinyl acetate andethylene production, and those of fugitive emissions from ethylene, butanoland octanol, propylene epoxide, polyethylene and glycol production wereobtained. Various manufacturing technologies and raw materials led todiscrepancies in source profiles between our domestic field tests and foreignresults for synthetic rubber and ethylene production. The provincial NMVOCemissions were calculated to increase from 1774 Gg in 2005 to 2507 Gg in2014, and relatively large emission densities were found in cities along theYangtze River with developed economies and industries. The estimates werelarger than those from most other available inventories, due mainly to thecomplete inclusion of emission sources and to the elevated activity levelsfrom plant-by-plant investigation in this work. Industrial processes andsolvent use were the largest contributing sectors, and their emissions wereestimated to increase, respectively, from 461 to 958 and from 38 to 966 Gg.Alkanes, aromatics and oxygenated VOCs (OVOCs) were the most importantspecies, accounting for 25.9–29.9, 20.8–23.2 and 18.2–21.0 % to annualtotal emissions, respectively. Quantified with a Monte Carlo simulation, theuncertainties of annual NMVOC emissions vary slightly through the years, andthe result for 2014 was −41 to +93 %, expressed as 95 %confidence intervals (CI). Reduced uncertainty was achieved compared toprevious national and regional inventories, attributed partly to the detailedclassification of emission sources and to the use of information at plantlevel in this work. Discrepancies in emission estimation were explored forthe chemical and refinery sectors with various data sources and methods.Compared with the Multi-resolution Emission Inventory for China (MEIC), thespatial distribution of emissions in this work were more influenced by thelocations of large point sources, and smaller emissions were found in urbanarea for developed cities in southern Jiangsu. In addition, discrepancieswere found between this work and MEIC in the speciation of NMVOC emissionsunder the atmospheric chemistry mechanisms CB05 and SAPRC99. The differencein species OLE1 resulted mainly from the updated source profile of buildingpaint use and the differences in other species from the varied sectorcontributions to emissions in the two inventories. The Community Multi-scaleAir Quality (CMAQ) model simulation was applied to evaluate the twoinventories, and better performance (indicated by daily 1 h maximum Oconcentrations in Nanjing) were found for January, April and October 2012when the provincial inventory was used.