Source characterization of highly oxidized multifunctional compounds in a boreal forest environment using positive matrix factorization
Source characterization of highly oxidized multifunctional compounds in a boreal forest environment using positive matrix factorization
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使用正矩阵分解对北方森林环境中高度氧化的多功能化合物进行来源表征
DOI：
10.5194/acp-16-12715-2016
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发表时间：
2016-10-12
影响因子：
6.3
通讯作者：
Ehn, Mikael
中科院分区：
文献类型：
--
作者：
Yan, Chao;Nie, Wei;Ehn, Mikael
抽象。高度氧化的多功能化合物（HOM）对大气二次有机气溶胶（SOA）和新粒子形成（NPF）具有重要作用，但大气HOM的主要形成途径尚不清楚。在这项研究中，硝酸根离子为基础的化学电离大气压界面飞行时间质谱仪（CI-APi-TOF）被部署到测量HOMs在北部森林Hyytiala，芬兰南部。正矩阵因子分解（PMF）被应用于分离检测到的HOM物种到几个因素，这些“因素”的合理形成途径。PMF进行了修订后的误差估计来自实验室数据，这与基于环境数据的估计吻合得很好。三个因素解释了大部分（> 95%）的数据变化，但最佳解决方案发现了六个因素，包括两个夜间因素，三个白天因素和一个运输因素。一个夜间因素是几乎相同的单萜臭氧分解产生的实验室光谱，而第二个可能代表单萜氧化开始NO3。确切的化学过程形成不同的白天因素仍然不清楚，但他们都有明显不同的昼夜配置文件，很可能与单萜氧化与NO的强烈影响，大概是通过其对过氧自由基（RO 2）化学的影响。除了这五个“本地”因素外，第六个因素被解释为与运输有关的因素。这些发现通过确认现有知识和启发未来的研究方向，提高了我们对HOM生产的理解，并为使用因子分解方法了解短寿命大气物种提供了新的视角。
Abstract. Highly oxidized multifunctional compounds (HOMs) have been demonstrated to be important for atmospheric secondary organic aerosols (SOA) and new-particle formation (NPF), yet it remains unclear which the main atmospheric HOM formation pathways are. In this study, a nitrate-ion-based chemical ionization atmospheric-pressure-interface time-of-flight mass spectrometer (CI-APi-TOF) was deployed to measure HOMs in the boreal forest in Hyytiala, southern Finland. Positive matrix factorization (PMF) was applied to separate the detected HOM species into several factors, relating these “factors” to plausible formation pathways. PMF was performed with a revised error estimation derived from laboratory data, which agrees well with an estimate based on ambient data. Three factors explained the majority (> 95 %) of the data variation, but the optimal solution found six factors, including two nighttime factors, three daytime factors, and a transport factor. One nighttime factor is almost identical to laboratory spectra generated from monoterpene ozonolysis, while the second likely represents monoterpene oxidation initiated by NO3. The exact chemical processes forming the different daytime factors remain unclear, but they all have clearly distinct diurnal profiles, very likely related to monoterpene oxidation with a strong influence from NO, presumably through its effect on peroxy radical (RO2) chemistry. Apart from these five “local” factors, the sixth factor is interpreted as a transport related factor. These findings improve our understanding of HOM production by confirming current knowledge and inspiring future research directions and provide new perspectives on using factorization methods to understand short-lived atmospheric species.