[Emission Characteristics and Chemical Components of PM_2.5 from Open Burning of Municipal Solid Waste]

Source emission measurements were employed to investigate open burning of municipal solid waste (MSW). Both barrel and natural pile-up burning of MSW were investigated using a self-designed dilution sampling system. PM_2.5 was collected for three types of waste, including rubber and plastic, paper, and wood and bamboo. Then, components in the samples were analyzed and emission factors of PM_2.5, organic carbon (OC), elemental carbon (EC), water-soluble ions and inorganic elements were calculated. The PM_2.5 emission factor was highest for wood and bamboo, and lowest for paper, and was calculated to be (7.44±0.76) g·kg^-1 and (2.72±0.52) g·kg^-1, respectively. Barrel burning resulted in much higher pollutant emissions. The PM_2.5 emission factor for barrel burning was 2.5-3.5 times that of natural pile-up burning. OC and EC were the main components of PM_2.5, with a proportion of 46.6%-67.2%. MSW composition had a greater effect on the OC/EC ratios than burning mode. The ratios could be helpful in the analysis of the emission contributions of different MSW components. The proportions of NH₄⁺ and Cl^- were the highest in water-soluble ions, accounting for 2.28%-6.35% and 1.04%-14.31%, respectively. Among inorganic elements, Ca, K, Fe, and Ba showed high emission factors. The emission factor of Zn was the highest among heavy metals, and other elements such as Cu, Cr, Sb, and Pb were also enriched. Zn emission was mainly determined by the burning mode; emissions from barrel combustion were approximately 20 times more than that of natural pile-up burning.