Preprints
https://doi.org/10.5194/egusphere-2024-2230
https://doi.org/10.5194/egusphere-2024-2230
23 Jul 2024
 | 23 Jul 2024

Seasonal Investigation of Ultrafine Particle Composition in an Eastern Amazonian Rainforest

Adam E. Thomas, Hayley S. Glicker, Alex B. Guenther, Roger Seco, Oscar Vega Bustillos, Julio Tota, Rodrigo A. F. Souza, and James N. Smith

Abstract. Reports on the composition of ultrafine (<100 nm in diameter) particles in the Amazon are scarce, due in part to the fact that new particle formation has rarely been observed near ground level. Ultrafine particles near the surface have nevertheless been observed, leaving open questions regarding the sources and chemistry of their formation and growth, particularly as these vary across seasons. Here we present measurements on the composition of ultrafine particles collected in the Tapajos National Forest (2.857° S, 54.959° W) during three different seasonal periods: 10–30 September 2016 (SEP), 18 November–23 December 2016 (DEC), and 22 May–21 June 2017 (JUN). Size-selected (5–70 nm) particles were collected daily (22 h) using an offline sampler. Samples collected during the three time periods were compiled and analyzed using liquid chromatography coupled to Orbitrap high resolution mass spectrometry. Our findings suggest a sustained influence of isoprene organosulfate chemistry on ultrafine particles in the different periods. We present chemical evidence that biological spore fragmentation impacted ultrafine particle composition during the late wet season (JUN), while chemical markers for biomass burning and secondary chemistry peaked during the dry season (SEP, DEC). Higher oxidation states and degrees of unsaturation were observed for organics in the dry season (SEP, DEC), suggesting greater extents of aerosol aging. Finally, applying a volatility parameterization to the observed compounds suggests organic sulfur species are likely key drivers of new particle growth in the region due to their low volatility compared to other species.

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Journal article(s) based on this preprint

27 Jan 2025
Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest
Adam E. Thomas, Hayley S. Glicker, Alex B. Guenther, Roger Seco, Oscar Vega Bustillos, Julio Tota, Rodrigo A. F. Souza, and James N. Smith
Atmos. Chem. Phys., 25, 959–977, https://doi.org/10.5194/acp-25-959-2025,https://doi.org/10.5194/acp-25-959-2025, 2025
Short summary
Adam E. Thomas, Hayley S. Glicker, Alex B. Guenther, Roger Seco, Oscar Vega Bustillos, Julio Tota, Rodrigo A. F. Souza, and James N. Smith

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2230', Alexander Vogel, 26 Aug 2024
  • RC2: 'Comment on egusphere-2024-2230', Anonymous Referee #2, 15 Sep 2024
  • AC1: 'Comment on egusphere-2024-2230', James Smith, 17 Oct 2024

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2230', Alexander Vogel, 26 Aug 2024
  • RC2: 'Comment on egusphere-2024-2230', Anonymous Referee #2, 15 Sep 2024
  • AC1: 'Comment on egusphere-2024-2230', James Smith, 17 Oct 2024

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by James Smith on behalf of the Authors (17 Oct 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (17 Oct 2024) by Joachim Curtius
RR by Alexander Vogel (18 Oct 2024)
ED: Publish as is (01 Nov 2024) by Joachim Curtius
AR by James Smith on behalf of the Authors (06 Nov 2024)

Journal article(s) based on this preprint

27 Jan 2025
Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest
Adam E. Thomas, Hayley S. Glicker, Alex B. Guenther, Roger Seco, Oscar Vega Bustillos, Julio Tota, Rodrigo A. F. Souza, and James N. Smith
Atmos. Chem. Phys., 25, 959–977, https://doi.org/10.5194/acp-25-959-2025,https://doi.org/10.5194/acp-25-959-2025, 2025
Short summary
Adam E. Thomas, Hayley S. Glicker, Alex B. Guenther, Roger Seco, Oscar Vega Bustillos, Julio Tota, Rodrigo A. F. Souza, and James N. Smith
Adam E. Thomas, Hayley S. Glicker, Alex B. Guenther, Roger Seco, Oscar Vega Bustillos, Julio Tota, Rodrigo A. F. Souza, and James N. Smith

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Short summary
We present measurements of the composition of ultrafine particles collected from the eastern Amazon, a relatively understudied region that is subjected to increasing human influence. We find that while isoprene chemistry is likely significant to ultrafine particle growth throughout the year, compounds related to other sources such as biological spore emissions and biomass burning exhibit striking seasonal differences, implying an extensive variation in regional ultrafine particle sources.