室内木柴燃烧排放水溶性离子粒径分布特征

基于实验室模拟燃烧和稀释通道采样系统,采用荷电低压撞击采样器采集了6种典型木柴燃烧排放的14级粒径段颗粒物.采用离子色谱分析了8种水溶性离子,获得水溶性离子的分粒径排放因子和排放特征.结果 表明,Ca2+的排放因子呈双峰分布,在0.25～0.38和2.5～3.6μm粒径段出现峰值,分别为0.14和0.16mg/kg.其...

Size distribution of water-soluble ions in particles emitted from domestic firewood burning

Six kinds of domestic firewood were burned in a laboratory. The emitted particles in fourteen sizes were collected using a dilution sampling system and an electrical low-pressure impactor. The emission characteristic and size-resolved emission factors (EFs) of eight types of water-soluble ions were identified. Results showed that the EFs of Ca²⁺ exhibited a bimodal size distribution, with peaks of 0.14 and 0.16mg/kg for particles within 0.25~0.38 and 2.5~3.6μm, respectively. The EFs of other ions were characterized by a unimodal size distribution. The EFs of NH₄⁺, NO₃^- and SO₄^2- peaked at 0.25~0.38μm, with peaks of 0.41, 0.58 and 0.84mg/kg, respectively. The EFs of K⁺ and Cl^- exhibited highest values at 0.15~0.25μm of 0.89 and 0.99mg/kg, respectively. The mass median diameters of total water-soluble ions from firewood burning were (0.30±0.07)μm, and those of individual ions ranged in 0.24~0.44μm. The EFs of water-soluble ions in PM_0.094, PM_0.94, PM_2.5 and PM₁₀ were 1.04~9.33, 5.00~48.87, 5.46~52.00 and 6.14~53.68mg/kg, respectively. The ratios of K⁺/Cl^-, K⁺/NO₃^-, K⁺/SO₄^2- and SO₄^2-/NO₃^- in particles emitted from firewood burning varied with particle size. Their primary emission values should be emphasized when they were used in source apportionment and smoke aging researches. The anion/cation equivalent ratios of PM₁₀ from firewood burning were 0.80±0.11. The acidity of PM_0.94 and PM_2.5 were higher than those of PM_0.094 and PM_2.5~10. This study is significant to establish emission inventory of size-resolved water-soluble ions, update and improve the parameter settings of corresponding climate and air quality models, and identify the evolution mechanisms of smokes during transport and aging.