Monoterpene chemical speciation in a tropical rainforest: variation with season, height, and time of day at the Amazon Tall Tower Observatory (ATTO)

TitleMonoterpene chemical speciation in a tropical rainforest: variation with season, height, and time of day at the Amazon Tall Tower Observatory (ATTO)
Publication TypeJournal Article
Year of Publication2018
AuthorsYanez-Serrano A.M, Nolscher A.C, Bourtsoukidis E., Alves E.G, Ganzeveld L., Bonn B., Wolff S., Sa M., Yamasoe M., Williams J., Andreae M.O, Kesselmeier J.
JournalAtmospheric Chemistry and Physics
Date Published2018/03
Type of ArticleArticle
ISBN Number1680-7316
Accession NumberWOS:000426918800004
Keywordsaerosol formation; alpha-pinene; beta-pinene; biogenic hydrocarbons; compounds voc; dry deposition; isoprene emissions; Meteorology & Atmospheric Sciences; oxidation; particle formation; volatile organic-compounds

Speciated monoterpene measurements in rainforest air are scarce, but they are essential for understanding the contribution of these compounds to the overall reactivity of volatile organic compound (VOC) emissions towards the main atmospheric oxidants, such as hydroxyl radicals (OH), ozone (O-3) and nitrate radicals (NO3). In this study, we present the chemical speciation of gas-phase monoterpenes measured in the tropical rainforest at the Amazon Tall Tower Observatory (ATTO, Amazonas, Brazil). Samples of VOCs were collected by two automated sampling systems positioned on a tower at 12 and 24m height and analysed using gas chromatography-flame ionization detection. The samples were collected in October 2015, representing the dry season, and compared with previous wet and dry season studies at the site. In addition, vertical profile measurements (at 12 and 24 m) of total monoterpene mixing ratios were made using proton-transfer-reaction mass spectrometry. The results showed a distinctly different chemical speciation between day and night. For instance, alpha-pinene was more abundant during the day, whereas limonene was more abundant at night. Reactivity calculations showed that higher abundance does not generally imply higher reactivity. Furthermore, inter-and intra-annual results demonstrate similar chemodiversity during the dry seasons analysed. Simulations with a canopy exchange modelling system show simulated monoterpene mixing ratios that compare relatively well with the observed mixing ratios but also indicate the necessity of more experiments to enhance our understanding of in-canopy sinks of these compounds.

Short TitleAtmos. Chem. Phys.
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