NO 3 radical, OH radical and O 3 -initiated secondary aerosol formation from aliphatic amines Xiaochen Tang a, b , Derek Price a, b , Eric Praske c , Su Anne Lee c , Morgan A. Shattuck c , Kathleen Purvis-Roberts c , Philip J. Silva d, e , Akua Asa-Awuku a, b , David R. Cocker III a, b, * a Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California, Riverside, CA 92521, USA b Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT), Riverside, CA 92507, USA c W.M. Keck Science Department of Claremont McKenna, Pitzer, and Scripps Colleges, 925 N. Mills Ave., Claremont, CA 91711, USA d USDA-ARS, 230 Bennett Lane, Bowling Green, KY 42104, USA e Department of Chemistry and Biochemistry, 0300 Old Main Hill, Utah State University, Logan, UT 84322-0300, USA highlights < We study the forming potential and composition of secondary aerosol from three aliphatic amines in the environmental chamber. < OH photooxidation and ozonolysis of the three amines lead to less amount of aerosol than reactions with nitrate radicals. < Negligible effect of water vapor has been observed on the aerosol yield of amine OH photooxidation. < Presence of water vapor impacts on salt formation in the nitrate radicaleamine reactions. < Acid-base reaction is a major pathway in reactions between nitrate radical and butylamine/diethylamine. article info Article history: Received 12 September 2012 Received in revised form 5 February 2013 Accepted 11 February 2013 Keywords: Secondary aerosol Amine Salt formation Relative humidity abstract Aliphatic amines enter the atmosphere from a variety of sources, and exist in both gas and particle phases in the atmosphere. Similar to ammonia, amines can form inorganic salts through acidebase re- actions. However, the atmospheric behavior of amines with atmospheric oxidants (e.g. the nitrate radical (NO 3 ), the hydroxyl radical (OH), O 3 ) is still poorly understood. In this study, chamber experiments were conducted to explore the reaction between three aliphatic amines and HNO 3 /O 3 /NO 3 /OH. Effects of water vapor were also explored by conducting experiments under different relative humidity conditions (RH<0.1% to w40%). Results show that all three amines have a high potential to form secondary aerosol in reactions with NO 3 , and are affected by the presence of water vapor. DEA and BA are capable of forming a significant amount of stable inorganic salt at ppb level concentrations, while TMA tends to form mostly non-salt secondary organic aerosol under dry conditions. The OH photooxidation of amines has much lower secondary aerosol yield and is independent of relative humidity, while ozonolysis produced negligible amount of aerosol. Secondary aerosol from OH oxidation was composed of organic components only, due to the lack of acid source. This study shows that night time chemistry of aliphatic amines can produce secondary organic and inorganic aerosol mixtures, and the relative contribution of each component depends on the environment relative humidity. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Atmospheric aerosols can be divided into two categories: pri- mary aerosol and secondary aerosol. Primary aerosols are directly emitted from a variety of sources (e.g. dust, sea salt, combustion emission, etc.), while secondary aerosols are formed in the atmo- sphere through a series of atmospheric reactions and gas-to- particle partitioning. Aerosols scatter and absorb solar and terres- trial radiation, influence cloud formation by acting as cloud condensation nuclei (CCN) and participate in heterogenous chem- ical reactions in the atmosphere, thereby affecting the abundance and distribution of atmospheric trace gases (Andreae and Crutzen, 1997; Haywood and Boucher, 2000). Atmospheric aerosols also have an important impact on human health (Pope and Dockery, * Corresponding author. University of California, Department of Chemical and Environmental Engineering, Bourns College of Engineering, CE-CERT, 1084 Columbia Ave., Riverside, CA 92507, USA. Tel.: þ1 951 781 5695; fax: þ1 951 781 5790. E-mail address: dcocker@engr.ucr.edu (D.R. Cocker). Contents lists available at SciVerse ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2013.02.024 Atmospheric Environment 72 (2013) 105e112