Formation and evolution of biogenic secondary organic aerosol over a forest site in Japan
Formation and evolution of biogenic secondary organic aerosol over a forest site in Japan
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DOI：
10.1002/2013jd020390
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发表时间：
2014-01-16
影响因子：
4.4
通讯作者：
Mochida, Michihiro
中科院分区：
文献类型：
--
作者：
Han, Yuemei;Iwamoto, Yoko;Mochida, Michihiro
2010年8月20日至30日，在日本的一个森林地点，使用Aerodyne高分辨率飞行时间气溶胶质谱仪对大气气溶胶颗粒的化学成分进行了表征。一个主要部分的非耐火亚微米气溶胶颗粒组成的有机物（占，平均而言，总质量的46%），硫酸盐（41%）和铵（12%）。正矩阵分解的高分辨率有机气溶胶质谱确定了两个含氧有机气溶胶（OOA）的组成部分：一个高度氧化，低挥发性OOA和氧化程度较低，半挥发性OOA（SV-OOA），主要解释为老化的区域有机气溶胶（OA）和当地形成的生物次生OA（BSOA），分别。SV-OOA的质量浓度在白天显著增加，这表明在非事件和新粒子形成事件的日子里，BSOA的光化学生产都很强。中午（当地时间13：00左右）后f（44）（OA质谱中m/z 44的分数）、CxOy+碎片分数和O/C比的增加表明OA变得越来越含氧，这可以通过新鲜形成的BSOA的老化来解释。高相对湿度条件下的水相氧化反应可能在这森林大气中BSOA的老化中发挥了至关重要的作用。有机物的质量浓度在小尺寸范围内（真空空气动力学直径小于300 nm）的大幅度增加，而硫酸盐的质量浓度没有增加，这表明BSOA的形成对研究区域周围云凝结核尺寸的颗粒的存在做出了主要贡献。
Chemical composition of atmospheric aerosol particles was characterized using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer at a forest site in Japan during 20-30 August 2010. A major fraction of nonrefractory submicron aerosol particles consisted of organics (accounting for, on average, 46% of total mass), sulfate (41%), and ammonium (12%). Positive matrix factorization of high-resolution organic aerosol mass spectra identified two oxygenated organic aerosol (OOA) components: a highly oxidized, low-volatility OOA and a less oxidized, semivolatile OOA (SV-OOA), interpreted mainly as aged regional organic aerosol (OA) and as locally formed biogenic secondary OA (BSOA), respectively. The mass concentrations of SV-OOA increased prominently during the daytime, suggesting a strong photochemical production of BSOA on both nonevent and new particle formation event days. Increases of f(44) (fraction of m/z 44 in OA mass spectrum), the fraction of CxOy+ fragment, and the O/C ratio after midday (around 13:00 local time) suggest that OA became increasingly oxygenated, which can be explained by the aging of freshly formed BSOA. Aqueous phase oxidation reactions under conditions of high relative humidity may have played a vital role in the aging of BSOA in this forest atmosphere. A substantial increase of the mass concentration of organics in the small size range (below 300nm in vacuum aerodynamic diameter), without an increase in that of sulfate, suggests that the formation of BSOA made a dominant contribution to the presence of particles of cloud condensation nuclei size around the studied area.