Rapidly changing coal-related city-level atmospheric mercury emissions and their driving forces

The up-to-date city-level mercury emission inventory is essential for effective mitigation policy designs due to rapid changes in energy consumption and industrial structures in Chinese cities. This study updated the atmospheric mercury emission inventory in 2015 based on the most recent information on plant-specific air pollution control devices (APCDs) and coal consumption for 45 sectors in 215 Chinese cities. Total emissions were estimated at 218 t with an uncertainty range of - 54.0% to 147%, to which coal-fired industrial boilers (CFIBs) contributed 58.1%, followed by coal-fired power plants (CFPPs, 32.7%). Mercury emissions varied significantly among cities, ranging from 0.0218 to 6.89 t. The Logistics Mean Division Index (LMDI) model was then applied to identify key factors driving mercury emission changes in 50 representative cities from 2010 to 2015. Although coal consumption increased by nearly one fifth across the 50 cities, their total emissions declined by 2.36%, largely due to energy structure adjustments and widespread installations of more efficient APCDs. However, key drivers of mercury mitigation differed widely between the cities, being driven by energy intensity improvements in Chongqing and Guangzhou (Guangdong province) and by energy structure adjustments in Wuhan (Hubei province) and Yinchuan (Ningxia province). Mitigation strategies should be tailored to reflect these differences.