Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest
<p>Reports on the composition of ultrafine particles (<span class="inline-formula"><100</span> nm in diameter) 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 su...
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Copernicus Publications
2025-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/959/2025/acp-25-959-2025.pdf |
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| author | A. E. Thomas H. S. Glicker A. B. Guenther R. Seco O. Vega Bustillos J. Tota R. A. F. Souza J. N. Smith |
| author_facet | A. E. Thomas H. S. Glicker A. B. Guenther R. Seco O. Vega Bustillos J. Tota R. A. F. Souza J. N. Smith |
| author_sort | A. E. Thomas |
| collection | DOAJ |
| description | <p>Reports on the composition of ultrafine particles (<span class="inline-formula"><100</span> nm in diameter) 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 of the composition of ultrafine particles collected in the Tapajós 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 (for 22 h each day) using an offline sampler. Samples collected during the three time periods were compiled and analyzed using liquid chromatography coupled with Orbitrap high-resolution mass spectrometry. Our findings suggest a sustained influence of isoprene organosulfate chemistry on ultrafine particles from the different periods. We present chemical evidence that indicates 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 and DEC). Higher oxidation states and degrees of unsaturation were observed for organics in the dry season (SEP and DEC), suggesting greater extents of aerosol aging. Finally, applying a volatility parameterization to the observed compounds suggests that organic sulfur species are likely key drivers of new-particle growth in the region due to their low volatility compared to other species.</p> |
| format | Article |
| id | doaj-art-f42748e569b84fce863bc057847f15e8 |
| institution | Kabale University |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj-art-f42748e569b84fce863bc057847f15e82025-01-27T09:40:25ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-01-012595997710.5194/acp-25-959-2025Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforestA. E. Thomas0H. S. Glicker1A. B. Guenther2R. Seco3O. Vega Bustillos4J. Tota5R. A. F. Souza6J. N. Smith7Department of Chemistry, University of California, Irvine, Irvine, CA, USADepartment of Chemistry, University of California, Irvine, Irvine, CA, USADepartment of Earth System Science, University of California, Irvine, Irvine, CA, USAInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Catalonia, SpainChemistry and Environment Center, Instituto de Pesquisas Energéticas e Nucleares, Cidade Universitária, São Paulo, BrazilInstitute of Engineering and Geoscience, Universidade Federal do Oeste do Pará, Santarém, BrazilEscola Superior de Tecnologia, Universidade do Estado do Amazonas, Manaus, BrazilDepartment of Chemistry, University of California, Irvine, Irvine, CA, USA<p>Reports on the composition of ultrafine particles (<span class="inline-formula"><100</span> nm in diameter) 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 of the composition of ultrafine particles collected in the Tapajós 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 (for 22 h each day) using an offline sampler. Samples collected during the three time periods were compiled and analyzed using liquid chromatography coupled with Orbitrap high-resolution mass spectrometry. Our findings suggest a sustained influence of isoprene organosulfate chemistry on ultrafine particles from the different periods. We present chemical evidence that indicates 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 and DEC). Higher oxidation states and degrees of unsaturation were observed for organics in the dry season (SEP and DEC), suggesting greater extents of aerosol aging. Finally, applying a volatility parameterization to the observed compounds suggests that organic sulfur species are likely key drivers of new-particle growth in the region due to their low volatility compared to other species.</p>https://acp.copernicus.org/articles/25/959/2025/acp-25-959-2025.pdf |
| spellingShingle | A. E. Thomas H. S. Glicker A. B. Guenther R. Seco O. Vega Bustillos J. Tota R. A. F. Souza J. N. Smith Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest Atmospheric Chemistry and Physics |
| title | Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest |
| title_full | Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest |
| title_fullStr | Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest |
| title_full_unstemmed | Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest |
| title_short | Seasonal investigation of ultrafine-particle organic composition in an eastern Amazonian rainforest |
| title_sort | seasonal investigation of ultrafine particle organic composition in an eastern amazonian rainforest |
| url | https://acp.copernicus.org/articles/25/959/2025/acp-25-959-2025.pdf |
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