Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Sci Total Environ. 2013 Jul 1;456-457:1-8. doi: 10.1016/j.scitotenv.2013.03.006. Epub 2013 Apr 9.
Airborne particles in Beijing during haze days and non-haze days were collected by an eleven-stage cascade impactor (MOUDI 110, MSP, USA), and the mass concentrations and water soluble inorganic ions of the size segregated airborne particles were quantitatively analyzed. PM10 concentrations during haze days ranged from 250.5 to 519.4 μgm(-3) which were about 3-8 times greater than those (ranged from 67.6 to 94.0 μgm(-3)) during non-haze days, and PM1.8 concentrations during haze periods were in the range of 117.6-378.6 μgm(-3) which were 3-14 times higher than those (27.0 to 36.8 μgm(-3)) during non-haze days. In comparison with non-haze days, all water soluble inorganic ions investigated in the airborne particles greatly enhanced during haze days. NH₄(+), NO₃(-) and SO₄(2-) were found to be the dominant water soluble inorganic ions, accounting for 91-95% of the total inorganic ions in PM1.8 during haze days, and 73-81% during non-haze days. The size distributions of SO₄(2-), NO₃(-), Cl(-), K(+) and Na(+) exhibited bimodal types, while single mode was found for NH₄(+), Ca(2+) and Mg(2+). Only with exception of Ca(2+) and Mg(2+), all ions were concentrated in fine particles around 0.56-1.0 μm of "droplet mode" during haze days, while 0.32-0.56 μm of "condensation mode" during non-haze days. The extremely high mole ratio (>2) of [NH4(+)]/[SO₄(2-)] during haze days implied that the main form of ammonium in PM1.8 might be (NH4)₂SO₄ and NH₄NO₃. The mass ratio of NO₃(-)/SO₄(2-) was >1 in PM1.8 during haze days and ~1 during non-haze days, indicating that NOx from the vehicle exhaust in Beijing is playing more and more important role on fine particle formation.
在雾霾天和非雾霾天，利用十一阶段冲击器（MOUDI 110，MSP，美国）收集北京空气中的悬浮颗粒，定量分析了按粒径分段采集的悬浮颗粒的质量浓度和水溶性无机离子。雾霾天的 PM10 浓度范围为 250.5 至 519.4μg/m³，约为非雾霾天（范围为 67.6 至 94.0μg/m³）的 3 至 8 倍，雾霾期间的 PM1.8 浓度范围为 117.6 至 378.6μg/m³，是非雾霾天（27.0 至 36.8μg/m³）的 3 至 14 倍。与非雾霾天相比，雾霾天空气中的所有水溶性无机离子都大大增加。NH₄(+)、NO₃(-)和 SO₄(2-)是主要的水溶性无机离子，占 PM1.8 中总无机离子的 91-95%，而非雾霾天占 73-81%。SO₄(2-)、NO₃(-)、Cl(-)、K(+)和 Na(+)的粒径分布呈双峰型，而 NH₄(+)、Ca(2+)和 Mg(2+)呈单峰型。只有 Ca(2+)和 Mg(2+)除外，所有离子都在雾霾天 0.56-1.0μm 的“液滴模态”细颗粒中浓缩，而非雾霾天在 0.32-0.56μm 的“凝结模态”细颗粒中浓缩。雾霾天[NH4(+)]/[SO₄(2-)]的摩尔比（>2）极高，表明 PM1.8 中铵的主要形式可能是(NH4)₂SO₄ 和 NH₄NO₃。雾霾天 PM1.8 中 NO₃(-)/SO₄(2-)的质量比大于 1，而非雾霾天约为 1，表明北京汽车尾气中的 NOx 在细粒子形成中发挥的作用越来越大。
