Linking biogenic hydrocarbons to biogenic aerosol in the Borneo rainforest

Abstract

Abstract. Emissions of biogenic volatile organic compounds are though to contribute significantly to secondary organic aerosol formation in the tropics, but understanding these transformation processes has proved difficult, due to the complexity of the chemistry involved and very low concentrations. Aerosols from above a Southeast Asian tropical rainforest in Borneo were characterised using liquid chromatography-ion trap mass spectrometry, high-resolution aerosol mass spectrometry and Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) techniques. Oxygenated compounds were identified in ambient organic aerosol that could be directly traced back to isoprene, monoterpenes and sesquiterpene emissions, by combining field data on chemical structures with mass spectral data generated from synthetically produced products created in a simulation chamber. Eighteen oxygenated species of biogenic origin were identified in the rainforest aerosol from the precursors isoprene, α-pinene, limonene, α-terpinene and β-caryophyllene. The observations provide the unambiguous field detection of monoterpene and sesquiterpene oxidation products in SOA above a pristine tropical rainforest. The presence of 2-methyl tetrol organosulfates and an associated sulfated dimer provides direct evidence that isoprene in the presence of sulfate aerosol can make a contribution to biogenic organic aerosol above tropical forests. High-resolution mass spectrometry indicates that sulfur can also be incorporated into oxidation products arising from monoterpene precursors in tropical aerosol.

Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water

“…In the Amazon, Kourtchev et al (2016) previously found a similar subset of these unidentified CHOS compounds in SOA samples, suggesting a biogenic influence. Many organosulfates and nitrooxy-organosulfates, previously reported in laboratory studies, ambient aerosols, and cloud water as derived from monoterpene oxidation (Boone et al, 2015;Hamilton et al, 2013;Iinuma et al, 2007aIinuma et al, , b, 2009Kristensen et al, 2016;Kristensen and Glasius, 2011;Lin et al, 2012;Mazzoleni et al, 2012;Nguyen et al, 2012b;Nozière et al, 2010;O'Brien et al, 2014;Pratt et al, 2013;Stone et al, 2012;Surratt et al, 2008), were detected in the biogenic-influenced cloud water samples (Table 2), also consistent with monoterpene emissions along the air mass trajectories (Guenther et al, 2006). In this study, the required solid-phase extraction step precluded the detection of isoprene-derived organosulfates, which would have been removed prior to analysis.…”

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO<sub>2</sub>, H<sub>2</sub>O and dimethyl sulfide

“…However, some regions will be impacted by both high isoprene and DMS concentrations, for example tropical islands, such as Borneo, which can have high isoprene concentrations and are strongly influenced by marine air masses (MacKenzie et al, 2011), as well as significant terrestrial sources from vegetation and soils in the Amazon, especially into the evening and at night (Jardine et al, 2015), when ozonolysis chemistry is at its most effective relative to photochemical OH chemistry. High sulfate composition of organic aerosols collected from the Borneo rainforests likely arises from the chemical processing of oceanic emissions of DMS and SO 2 (Hamilton et al, 2013). The sulfate content of aerosols was observed to increase further over oil palm plantations in Borneo, where isoprene concentrations may reach levels on the order of tens of ppbv (MacKenzie et al, 2011), indicating scope for alkene ozonolysis-DMS chemical interactions to become significant.…”

Characterization of organic nitrogen in aerosols at a forest site in the southern Appalachian Mountains

“…Studies of secondary organic aerosol (SOA) have identified a variety of nitrated organosulfate compounds (e.g., nitrooxy-organosulfates) in both chamber and ambient aerosol samples following isoprene and monoterpene oxidation. These compounds are either produced under high NO x conditions or from nighttime NO 3 radical chemistry (Surratt et al, 2006Darer et al, 2011;Lin et al, 2013a;He et al, 2014;Worton et al, 2013). Potential SOA precursors such as unsaturated green leaf volatiles (GLVs) released by wounded plants (e.g., crop harvesting and insect attacks) may contribute substantially to the budget of biogenic SOA formation, especially in remote forests Hamilton et al, 2013;Shalamzari et al, 2016).…”

“…These compounds are either produced under high NO x conditions or from nighttime NO 3 radical chemistry (Surratt et al, 2006Darer et al, 2011;Lin et al, 2013a;He et al, 2014;Worton et al, 2013). Potential SOA precursors such as unsaturated green leaf volatiles (GLVs) released by wounded plants (e.g., crop harvesting and insect attacks) may contribute substantially to the budget of biogenic SOA formation, especially in remote forests Hamilton et al, 2013;Shalamzari et al, 2016). The detection of reaction products such as organosulfates and nitrooxy-organosulfates in ambient aerosols provides strong evidence of influence from anthropogenic sources (e.g., SO 2 and NO x ) interacting with biogenic precursors to form nitrogenated SOA Lin et al, 2013a;Meade et al, 2016).…”