[Emission Factors of Heavy Metals in Size-resolved Particles Emitted from Residential Coal Combustion].

Based on a dilution sampling system and domestic burning tests, size-segregated particles emitted from burning of three kinds of honeycomb coals (in view of flaming and smoldering burning conditions) and four kinds of raw coals, were collected by cascade impactors (FA-3). The contents of V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Sb, and Pb were analyzed to get their emission factors (EFs) in different particle size fractions. Results indicated that:① Zn and Pb dominated the emitted mass of heavy metals from chunk (53.16%-65.76%) and honeycomb (96.08% in 0.43 µm) during the flaming combustion condition. However, the emission of Ni was increased from 30.70% to 52.36% in the smoldering condition. Thus, combustion condition may affect the composition of heavy metals in particle matters. ② In the flaming condition, both chunk and honeycomb emission factors of heavy metals were concentrated under 1.1 µm, while the larger sized particles in the range of 5.8-10 µm were distributed. So, heavy metal components may shift to the larger size of the particles at lower combustion temperatures. ③ Fine particle matters(PM) was divided into three categories based on the size distribution of 11 kinds of heavy metal emission factors. The maximum emission values of As and V fell under the PM size category of 5.8-10 µm. The fourth cycle transition metal elements, such as Cr, Mn, Cu, Ni, and Co, fell in the range of 1.1-2.1 µm and these elements represented similar emission characteristic features. Other elements, such as Pb, Sb, Cd, and Zn, were concentrated in sizes less than 0.43 µm. ④ The additive in the honeycomb during the process may import several kinds of heavy metals and may change the combustion temperature, which remodels the mechanism of heavy metal emission. Thus, honeycomb coal may emit different heavy metals under different combustion conditions.The heavy metal emission mechanism during honeycomb coal combustion needs further investigation and the emission reduction effects (especially of heavy metals) needs to be re-estimated.

[Size-resolved Emission Factors of Carbonaceous Particles from Domestic Coal Combustion in China].

China is one of the most important contributors to the global burden of carbonaceous aerosols, of which domestic coal combustion occupies a large fraction. Uncertainty in the emission factors (EFs) directly influences the accuracy of corresponding emission inventories. In the present study, based on domestic burning tests with a dilution sampling system, nine size-segregated particle classes emitted from the burning of three kinds of honeycomb coals (under flaming and smoldering burning conditions) and four kinds of chunk coals, including bituminous and lignite, were collected via a cascade impactor (FA-3). Organic and elemental carbon (OC and EC, respectively) were analyzed using the thermal-optical method. The EFs of particulate matter (PM), OC, and EC for nine size ranges were obtained. For honeycomb coals, the EFs of OC and EC in PM2.1 were 0.07 g·kg-1 and 0.002 g·kg-1, respectively, under flaming burning conditions and 0.10 g·kg-1 and 0.001 g·kg-1, respectively, under smoldering burning conditions. Carbonaceous particles exhibited higher EFs under flaming burning conditions. For chunk coals, the EFs of OC and EC in PM2.1 were 1.4 g·kg-1 and 0.02 g·kg-1, respectively, which are about one magnitude higher than those for honeycomb coal burning. Particulate matter and its associated carbonaceous components preferred to concentrate in fine particles. The EFs of carbonaceous components peaked at the size of ≤ 0.43 µm and 0.43-0.65 µm for honeycomb coal burning and chunk coal burning, respectively.

[Emission Inventory of Heavy Metals in Fine Particles Emitted from Residential Coal Burning in China].

Based on a dilution sampling system and domestic burning tests, emission factors (EFs) for eleven heavy metals of V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Sb and Pb in PM2.5 from raw coal and honeycoal burning were calculated, using their contents in raw coals of different provinces. Then the total emission amounts of heavy metals from residential coals burning in 2012 were calculated and 30 km×30 km grid cell-based emission inventories were established. The results showed that the EFs of Pb, Zn, As and Cu were higher from honeycomb coal burning. They were 27.1, 16.8, 0.99 and 0.97 mg·kg-1, which were 56, 6, 10 and 2 times of those for raw coal, respectively. The total emissions of V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Sb and Pb in PM2.5 from residential coal burning in 2012 were 0.5, 30.1, 59.5, 1.1, 29.3, 20.0, 188.9, 64.9, 1.6, 3.4 and 176.7 t. Hunan, Hebei, Inner Mongolia, Henan, and Shandong held higher emission amounts, which were 12.4%, 12.3%, 10.4%, 9.9% and 9.3% of the total emissions of the whole country. Beijing, Henan, Shandong, Hunan, Jiangxi, Guizhou and Inner Mongolia were the regions with higher emission intensities and emission amounts per capita. The spatial distribution showed that the regions with higher annual emissions of Zn and Pb distributed widely, mainly in Inner Mongolia, Hebei, Beijing, Tianjin, Shandong, Henan, Gansu, Hunan and Jiangxi. The emission inventories for heavy metals in fine particles established here are important for regional air quality modeling and human health risk assessment.