Refined spatio-temporal emission assessment of Hg, As, Cd, Cr and Pb from Chinese coal-fired industrial boilers

Coal-fired industrial boilers (CFIBs) are a significant source of trace metals (TMs) emissions, due to its large number and widespread industry application. In this study, a highly resolved of county-based atmospheric emission inventory of Hg, As, Cd, Cr and Pb for Chinese CFIBs in 2017 is established firstly based on integrated source-specific information of both activity level and air pollution control devices (APCDs) from ~61,000 CFIBs in mainland China. Our results estimated that the total emissions of Hg, As, Cd, Cr and Pb from national CFIBs in 2017 were about 25.46, 115.33, 7.04, 371.40, and 589.76 t, respectively. Hg0 was the majority species of atmospheric Hg, accounting for 71.5% of the total Hg emission. The peak emission intensities of five TMs were mainly concentrated in northern and eastern region of China due to its large demand of coal consumption for winter heating, broad economic activity, as well as high population density. Monthly emission characteristics of TMs exhibited seasonal peak. The overall uncertainties of the newly updated emission inventory were estimated at the ranges of −42.0%–45.5%. Generally, TMs emissions from Chinese CFIBs were effectively controlled through implementing energy substitution, APCDs upgrading, and ultra-low emission (ULE) retrofitting in different regions of China, which contributed to 18.8%–29.4% of five TMs emission reductions. We believe that our highly resolved county-level emission inventory will be comprehensively explored the current tempo-spatial emission characteristics of atmospheric TMs from Chinese CFIBs and the forecast results will be useful for developing effective emission control programs for policy makers in the county levels and improving the regional air quality in the future. [Display omitted] •County-based emission inventory of Hg, As, Cd, Cr, Pb in 2017 is developed firstly.•Speciation profiles of Hg in flue gas of CFIBs with varied APCDs are detailed.•Intensive emissions of TMs were mainly concentrated in northern and eastern region.•Monthly emission characteristics of five TMs exhibited seasonal peak.•Emission reductions of five TMs reach to 18.8– 29.4% under three scenarios in 2020.