Observations of sesquiterpenes and their oxidation products in central Amazonia during the wet and dry seasons

摘要: Abstract. Biogenic volatile organic compounds (BVOCs) from the Amazon forest region represent largest source of carbon emissions to atmosphere globally. These BVOC dominantly consist and intermediate-volatility terpenoid that undergo chemical transformations in form oxygenated condensable gases secondary aerosol (SOA). We collected quartz filter samples with 12 h time resolution performed hourly situ measurements a semi-volatile thermal desorption gas chromatograph (SV-TAG) at rural site ( T3 ) located west urban center Manaus, Brazil as part Green Ocean (GoAmazon2014/5) field campaign measure BVOCs their oxidation products during wet dry seasons. speciated quantified 30 sesquiterpenes 4 diterpenes mean concentrations range 0.01–6.04 ng m−3 (1–670 ppqv). estimate contribute approximately 14 12 % total reactive loss O3 via reaction isoprene or terpenes seasons, respectively. This is reduced  ∼  50–70 % for within-canopy attributed ozonolysis highly (e.g., β-caryophyllene) are reacted away before reaching our measurement site. further identify suite particle phases explore role biogenic SOA formation central region. Synthesized authentic standards were also used quantify gas- particle-phase derived β-caryophyllene. Using tracer-based scaling methods these products, we roughly sesquiterpene contributes least 0.4–5 % (median 1 %) submicron OA mass. However, this likely low-end estimate, evidence additional unaccounted clearly exists. By comparing data laboratory-based experiments confirm more than 40 observed produced through present Amazonian SOA, warranting efforts towards complete quantification.