Source characterization of highly oxidized multifunctional compounds in a boreal forest environment using positive matrix factorization
Chao Yan1,Wei Nie2,1,Mikko Äijälä1,Matti P. Rissanen1,Manjula R. Canagaratna3,Paola Massoli3,Heikki Junninen1,Tuija Jokinen1,a,Nina Sarnela1,Silja A. K. Häme1,Siegfried Schobesberger1,b,Francesco Canonaco4,Lei Yao5,André S. H. Prévôt4,Tuukka Petäjä1,2,Markku Kulmala1,Mikko Sipilä1,Douglas R. Worsnop1,3,and Mikael Ehn1Chao Yan et al. Chao Yan1,Wei Nie2,1,Mikko Äijälä1,Matti P. Rissanen1,Manjula R. Canagaratna3,Paola Massoli3,Heikki Junninen1,Tuija Jokinen1,a,Nina Sarnela1,Silja A. K. Häme1,Siegfried Schobesberger1,b,Francesco Canonaco4,Lei Yao5,André S. H. Prévôt4,Tuukka Petäjä1,2,Markku Kulmala1,Mikko Sipilä1,Douglas R. Worsnop1,3,and Mikael Ehn1
1Department of Physics, University of Helsinki, Helsinki, 00140,
Finland
2Joint International Research Laboratory of Atmospheric and Earth
System Sciences, School of Atmospheric Sciences, Nanjing University,
Nanjing, 210046, China
3Aerodyne Research, Inc., Billerica, MA 01821, USA
4Laboratory of Atmospheric Chemistry, Paul Scherrer Institute,
Villigen, 5232, Switzerland
5Shanghai Key Laboratory of Atmospheric Particle Pollution and
Prevention (LAP3), Department of Environmental Science & Engineering,
Fudan University, Shanghai, 200433, China
anow at: Department of Chemistry, University of California, Irvine, CA,
92617, USA
bnow at: Department of Atmospheric Sciences, University of Washington,
Seattle, Washington 98195, USA
1Department of Physics, University of Helsinki, Helsinki, 00140,
Finland
2Joint International Research Laboratory of Atmospheric and Earth
System Sciences, School of Atmospheric Sciences, Nanjing University,
Nanjing, 210046, China
3Aerodyne Research, Inc., Billerica, MA 01821, USA
4Laboratory of Atmospheric Chemistry, Paul Scherrer Institute,
Villigen, 5232, Switzerland
5Shanghai Key Laboratory of Atmospheric Particle Pollution and
Prevention (LAP3), Department of Environmental Science & Engineering,
Fudan University, Shanghai, 200433, China
anow at: Department of Chemistry, University of California, Irvine, CA,
92617, USA
bnow at: Department of Atmospheric Sciences, University of Washington,
Seattle, Washington 98195, USA
Correspondence: Chao Yan (chao.yan@helsinki.fi) and Wei Nie (niewei@nju.edu.cn)
Received: 29 Apr 2016 – Discussion started: 12 May 2016 – Revised: 16 Aug 2016 – Accepted: 06 Sep 2016 – Published: 12 Oct 2016
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 Hyytiälä, 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.
Highly oxidized multifunctional compounds (HOMs) are known to have a significant contribution to secondary aerosol formation, yet their dominating formation pathways remain unclear in the atmosphere. We apply positive matrix factorization (PMF) on HOM data, and successfully retrieve factors representing different formation pathways. The results improve our understanding of HOM formation, and provide new perspectives on using PMF to study the variation of short-lived specie.
Highly oxidized multifunctional compounds (HOMs) are known to have a significant contribution to...
