Preprints
https://doi.org/10.5194/egusphere-2024-1210
https://doi.org/10.5194/egusphere-2024-1210
25 Apr 2024
 | 25 Apr 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Investigating Carbonyl Compounds above the Amazon Rainforest using PTR-ToF-MS with NO+ Chemical Ionization

Akima Ringsdorf, Achim Edtbauer, Bruna Holanda, Christopher Poehlker, Marta O. Sá, Alessandro Araújo, Jürgen Kesselmeier, Jos Lelieveld, and Jonathan Williams

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.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Akima Ringsdorf, Achim Edtbauer, Bruna Holanda, Christopher Poehlker, Marta O. Sá, Alessandro Araújo, Jürgen Kesselmeier, Jos Lelieveld, and Jonathan Williams

Status: open (until 14 Jun 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
Akima Ringsdorf, Achim Edtbauer, Bruna Holanda, Christopher Poehlker, Marta O. Sá, Alessandro Araújo, Jürgen Kesselmeier, Jos Lelieveld, and Jonathan Williams
Akima Ringsdorf, Achim Edtbauer, Bruna Holanda, Christopher Poehlker, Marta O. Sá, Alessandro Araújo, Jürgen Kesselmeier, Jos Lelieveld, and Jonathan Williams

Viewed

Total article views: 267 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
198 62 7 267 22 5 6
  • HTML: 198
  • PDF: 62
  • XML: 7
  • Total: 267
  • Supplement: 22
  • BibTeX: 5
  • EndNote: 6
Views and downloads (calculated since 25 Apr 2024)
Cumulative views and downloads (calculated since 25 Apr 2024)

Viewed (geographical distribution)

Total article views: 263 (including HTML, PDF, and XML) Thereof 263 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 19 May 2024
Download
Short summary
We show the average height distribution of separately observed aldehydes and ketones over a day and discuss their rainforest-specific sources and sinks and their seasonal changes above the Amazon rainforest. Ketones have much longer atmospheric lifetimes than aldehydes, and thus different implications for atmospheric chemistry. However, they are commonly observed together, which we overcome by measuring with a NO+ chemical ionization mass spectrometer for the first time in the Amazon rainforest.