Characterization and emission factors of carbonaceous aerosols originating from coke production in China.

Coking is a substantial source of carbonaceous aerosols in China, but the emission characteristics and pollution levels of coking-produced organic carbon (OC) and elemental carbon (EC) remain unknown, causing considerable uncertainty in emission estimates. In this study, the emission factors of OC (EF) and EC (EF) of typical coking plants in Shanxi, China, were measured. The measured EF and EF from fugitive emissions (7.43 and 9.54 g/t) were significantly higher than those from flue gas (1.67 and 3.71 g/t). The technological conditions of coke production affect the emissions of OC and EC. For example, the total emissions from coke plants that use 3.2-m-high coke ovens were greater than those from plants that use 4.3- and 6-m-high ovens. The EF and EF for plants conducting stamp charging were considerably higher than those for plants using top charging. The stable carbon isotopes of total carbon (δC), OC (δC), and EC (δC) for fly ash during coking were -23.74‰ to -24.17‰, -23.32‰ to -23.87‰, and -23.84‰ to -24.14‰, respectively, and no clear isotopic fractionation was found during coke production. Different EC/OC ratios from different emission pathways and the carbon isotope signature of coke production should be considered when investigating the sources of carbonaceous aerosols. The total estimated EC and OC emissions from coke production in China were 3.93 and 5.72 Gg in 2017, and Shanxi, Hebei, and Shaanxi made the largest contributions.