A chamber study of the influence of boreal BVOC emissions and sulfuric acid on nanoparticle formation rates at ambient concentrations

M Dal Maso,R Tillmann,L Liao,K Lehtipalo,M Sipilä,D Worsnop,M Kulmala,J Wildt,V.-M Kerminen,T Mentel,M Ehn,A Kiendler-Scharr,J Hakala,E Kleist

doi:10.5194/acp-16-1955-2016

Abstract

Abstract. Aerosol formation from biogenic and anthropogenic precursor trace gases in continental background areas affects climate via altering the amount of available cloud condensation nuclei. Significant uncertainty still exists regarding the agents controlling the formation of aerosol nanoparticles. We have performed experiments in the Jülich plant–atmosphere simulation chamber with instrumentation for the detection of sulfuric acid and nanoparticles, and present the first simultaneous chamber observations of nanoparticles, sulfuric acid, and realistic levels and mixtures of biogenic volatile compounds (BVOCs). We present direct laboratory observations of nanoparticle formation from sulfuric acid and realistic BVOC precursor vapour mixtures performed at atmospherically relevant concentration levels. We directly measured particle formation rates separately from particle growth rates. From this, we established that in our experiments, the formation rate was proportional to the product of sulfuric acid and biogenic VOC emission strength. The formation rates were consistent with a mechanism in which nucleating BVOC oxidation products are rapidly formed and activate with sulfuric acid. The growth rate of nanoparticles immediately after birth was best correlated with estimated products resulting from BVOC ozonolysis.

Highlights

Studies in ambient environments have identified several strong candidates to act as the responsible agents for nanoparticle formation, the strongest being the sulfuric acid molecule, H2SO4 (Weber et al, 1996; Sipila et al, 2010; Kuang et al, 2008)
We found that during a single event, after the initial burst of particles, sulfuric acid concentrations slowly increased as time progressed; simultaneously, particle formation rates increased proportionally to the H2SO4 concentration
This is the first time that nanoCN, H2SO4, and realistic levels and mixtures of biogenic volatile compounds (BVOCs) have been observed in controlled laboratory conditions

Summary

Introduction

Studies in ambient environments have identified several strong candidates to act as the responsible agents for nanoparticle formation, the strongest being the sulfuric acid molecule, H2SO4 (Weber et al, 1996; Sipila et al, 2010; Kuang et al, 2008). Recent experimental and theoretical evidence has shown that basic gases, e.g. ammonia or certain amines could act as such stabilizing agents (Almeida et al, 2013; Smith et al, 2010; Berndt et al, 2010). In addition to these bases, various organic compounds have been proposed to participate in the particle formation process (Zhang et al, 2004; Paasonen et al, 2010; Metzger et al, 2010; O’Dowd et al, 2002). Particle formation has been shown to correlate positively with the amount of precursor BVOCs, and to depend strongly on the composition of emitted BVOC mixture

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