Earth Observatory of Singapore , Nanyang Technological University , Singapore 639798.
Campus for Research Excellence and Technological Enterprise (CREATE) Programme , Singapore 138602.
Environ Sci Technol. 2019 Sep 3;53(17):10034-10042. doi: 10.1021/acs.est.9b01696. Epub 2019 Aug 14.
The importance of water-soluble organic matter (WSOM) on the hygroscopic growth of particles is recognized, yet roles of different categories of WSOM are under debate. We segregated WSOM from Indonesian biomass burning particles by the 1-octanol-water partitioning method. The method is based on the 1-octanol-water partition coefficient (), which correlates with water solubility. The segregated WSOM was analyzed using the humidified tandem differential mobility analyzer (HTDMA) and time-of-flight aerosol chemical speciation monitor (ToF-ACSM). Both the hygroscopicity parameter and the fractional contribution of / 44 (), which serves as a metric for degree of oxygenation, increased with polarity. This result experimentally evidenced that highly polar/water-soluble OM is highly hygroscopic/oxygenated. Positive matrix factorization (PMF) identified three factors from the ToF-ACSM data. Deconvolution of by PMF factors demonstrated that the less polar fractions, which occupy approximately 20-60% of WSOM dependent on the biomass type, almost do not contribute to water uptake under subsaturated conditions. This result highlights that categorization of WSOM will be needed to understand how hygroscopic growth of aerosol particles is regulated.
水溶性有机物 (WSOM) 对颗粒吸湿性增长的重要性已得到认可，但不同类别 WSOM 的作用仍存在争议。我们采用 1-辛醇-水分配法从印度尼西亚生物质燃烧颗粒物中分离 WSOM。该方法基于与水溶性相关的 1-辛醇-水分配系数 ()。分离出的 WSOM 采用加湿串联差分迁移率分析仪 (HTDMA) 和飞行时间气溶胶化学特性监测仪 (ToF-ACSM) 进行分析。吸湿性参数 和 / 44 的分数贡献 ()，这是氧化程度的指标，均随极性增加而增加。这一结果从实验上证明了高极性/高水溶性有机物质具有高吸湿性/高氧化性。利用飞行时间气溶胶化学特性监测仪数据的正定矩阵因子分解 (PMF) 确定了三个因子。PMF 因子对 的反卷积表明，在亚饱和条件下，大约占 WSOM 20-60%的非极性分数几乎不会对水分吸收产生贡献。这一结果强调，需要对 WSOM 进行分类，以了解气溶胶颗粒吸湿性增长是如何受到调控的。
