Investigating carbonyl compounds above the Amazon rainforest using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) with NO + chemical ionization
Year: 2024
Type: article
Abstract: . The photochemistry of carbonyl compounds significantly influences tropospheric chemical composition by altering the local oxidative capacity, free radical abundance in the upper troposphere, and formation of ozone, PAN, and secondary organic aerosol particles. Carbonyl compounds can be emitted directly from the biosphere into the atmosphere and are formed through photochemical degradation of various precursor compounds. Aldehydes have atmospheric lifetimes of hours to days, in contrast to ketones, which persist for up to several weeks. While standard operating conditions for proton transfer time‑of‑flight mass spectrometer (PTR-ToF-MS) using H3O+ ions are unable to separate aldehydes and ketones, the use of NO+ reagent ions allows for the differential detection of isomeric carbonyl compounds with a high time resolution. Here we study the temporal (24 h) and vertical (80–325 m) variability of individual carbonyl compounds in the Amazon rainforest atmosphere with respect to their rainforest-specific sources and sinks. We found strong sources of ketones within or just above the rainforest canopy (acetone, MEK, and C5-ketones). A common feature of the carbonyls was nocturnal deposition observed by loss rates, most likely since oxidized volatile organic compounds are rapidly metabolized and utilized by the biosphere. With NO+ chemical ionization, we show that the dominant carbonyl species include acetone and propanal, which are present at a ratio of 1:10 in the wet–to–dry transition and 1:20 in the dry season.
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $1,725
Funders: Fundação de Amparo à Pesquisa do Estado de São Paulo, Bundesministerium für Bildung und Forschung, Ministério da Ciência, Tecnologia e Inovação, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Max-Planck-Gesellschaft, Financiadora de Estudos e Projetos, Fundação de Amparo à Pesquisa do Estado do Amazonas, Instituto Nacional de Pesquisas da Amazônia, Universidade do Estado do Amazonas
Awards: Amazonian Tall Tower Observatory (ATTO) zur Messung und langfristigen Beobachtung klimarelevanter Spurengase als Grundlage für verbesserte Modelle für die Klimaforschung, G3909708666, Verbundprojekt ATTO: Pilotprojekte - Teilprojekt 1: Messung, Auswertung und globale Einordung von Treibhausgasen am ATTO-Turm im Amazonas-Regenwald, Verbundprojekt ATTO: Pilotprojekte - Teilprojekt 2: Auswirkung von Spurengasen und Aerosolen auf Atmosphärenchemie und Klima im Zentralamazonas, G8320457871
OpenAlex ID: W4403734166