Chemical characterization of biogenic secondary organic aerosol generated from plant emissions under baseline and stressed conditions: inter- and intra-species variability for six coniferous species

Abstract

Abstract. The largest global source of secondary organic aerosol (SOA) in the atmosphere is derived from the oxidation of biogenic emissions. Plant stressors associated with a changing environment can alter both the quantity and composition of the compounds that are emitted. Alterations to the biogenic volatile organic compound (BVOC) profile could impact the characteristics of the SOA formed from those emissions. This study investigated the impacts of one global change stressor, increased herbivory, on the composition of SOA derived from real plant emissions. Herbivory was simulated via application of methyl jasmonate (MeJA), a proxy compound. Experiments were repeated under pre- and post-treatment conditions for six different coniferous plant types. Volatile organic compounds (VOCs) emitted from the plants were oxidized to form SOA via dark ozone-initiated chemistry. The SOA chemical composition was measured using a Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS). The aerosol mass spectra of pre-treatment biogenic SOA from all plant types tended to be similar with correlations usually greater than or equal to 0.90. The presence of a stressor produced characteristic differences in the SOA mass spectra. Specifically, the following m/z were identified as a possible biogenic stress AMS marker with the corresponding HR ion(s) shown in parentheses: m/z 31 (CH3O+), m/z 58 (C2H2O2+, C3H6O+), m/z 29 (C2H5+), m/z 57 (C3H5O+), m/z 59 (C2H3O2+, C3H7O+), m/z 71 (C3H3O2+, C4H7O+), and m/z 83 (C5H7O+). The first aerosol mass spectrum of SOA generated from the oxidation of the plant stress hormone, MeJA, is also presented. Elemental analysis results demonstrated an O : C range of baseline biogenic SOA between 0.3 and 0.47. The O : C of standard MeJA SOA was 0.52. Results presented here could be used to help identify a biogenic plant stress marker in ambient data sets collected in forest environments.

Environmental conditions regulate the impact of plants on cloud formation

“…It is possible that different plant species with different ages may exhibit different responses in VOC emissions to stresses and thus further change SOA composition and properties. For example, simulated herbivory on different tree species has been shown to cause different responses in VOC emissions, which alters the SOA composition with some variability 40 41 . Because various plant species with different ages as well as various environmental factors are involved and multiple factors can have synergistic or counteracting effects, the overall impacts are complex and cannot be assessed quantitatively here.…”

Oligomer and highly oxygenated organic molecule formation from oxidation of oxygenated monoterpenes emitted by California sage plants

“…For mainly isoprene-emitting plants, SOA yields from co-emitted VOCs were lower than expected from single-VOC data, suggesting that isoprene inhibits SOA formation (Wyche et al, 2014). Furthermore, the recent incorporation of terpene complexity into a box model has demonstrated enhancements of 1.5-2.3 in SOA mass yields from Scots pine, relative to the commonly used model monoterpene αpinene (Faiola et al, 2018). Although studies of SOA from real plant emissions are limited, all results show pronounced differences between plants and single components.…”

“…Despite this diversity, the chemical composition of SOA from the majority of these BVOCs remains unknown. Real plant emissions are mixtures of many BVOCs, yet it remains unclear if the compounds currently used as proxies for BVOCs are adequate to describe the SOA chemistry of plants globally (Faiola et al, 2018).…”

Introductory lecture: atmospheric chemistry in the Anthropocene

“…329 However, accurate assessment of biogenic emissions is challenging due to their dependence on a large number of factors such as plant type, temperature, sunlight intensity, soil characteristics, and stressors such as attack by insects. 330,331 Recent modelling efforts that include 147 individual species suggest that a relatively small number of compounds (about a dozen) are responsible for $80% of the BVOC emissions, with isoprene and the monoterpenes dominating. …”