the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 26 Jun 2025
Brown carbon emissions from laboratory combustion of Eurasian arctic-boreal and South African savanna biomass
Abstract. Warming climate is predicted to increase forest fires which can be a major source of black and brown carbon (BC and BrC) into the atmosphere. Unlike North American forest fires, very limited studies have characterized North Eurasian biomass burning (BB) emissions. In this work, we defined the emission factors of carbonaceous aerosols and characterized light absorption of BrC emitted from boreal and peat burning through offline filter extraction method. The results were compared to African savanna emissions. Effects of atmospheric dilution and oxidative aging on BrC absorptivity were investigated for selected BB emissions sampled into an environmental chamber. Organic carbon (OC) and elemental carbon (EC) emission factors of fresh BB emissions ranged between 1.30–89.9 g kg-1 and 0.01–4.80 g kg-1 respectively. Methanol soluble OC (MSOC) represented more than 92 % of fresh BB emissions but intrinsic chemical differences among samples resulted in MACMSOC values ranging from 0.46–1.48 m2 g-1 at 365 nm. Fresh BB emissions formed weakly absorbing BrC with k550_MSOC ranging from 0.002 and 0.011. Water soluble OC (WSOC) fractions varied among fresh BB emissions but overall exhibited higher MAC365 than MSOC. Dilution-related evaporative loss in environmental chamber resulted in less volatile OC, making them less soluble in methanol. Photochemical and dark oxidative aging further increased the ELVOC fraction of the organics along with oxidation state. Our estimated OC-EC emission factors and kMSOC for fresh BB emissions can be used for future modelling purposes. Further online measurements are needed to account for non-soluble strong BrC in aged BB emissions.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Atmospheric Chemistry and Physics. The peer-review process was guided by an independent editor, and the authors also have no other competing interests to declare.
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 paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.-
Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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Supplement
(1863 KB) - BibTeX
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Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-2759', Anonymous Referee #1, 21 Jul 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-2759/egusphere-2025-2759-RC1-supplement.pdfCitation: https://doi.org/
10.5194/egusphere-2025-2759-RC1 -
RC2: 'Comment on egusphere-2025-2759', Anonymous Referee #2, 18 Aug 2025
This manuscript presents a comprehensive investigation on the emission factors, chemical, and optical properties of organics from Eurasian arctic-boreal and South African savanna biomass combustion in the lab. Brown carbon (BrC) is an important light-absorbing component in aerosol that affects the radiative balance in the atmosphere. The manuscript also investigated the effects of atmospheric dilution and aging on the optical properties of BrC. There are two comments that I wish the authors can address in the revision.
General comments:
- It is stated in the abstract and conclusions that the comparison with African savanna biomass is an objective of this manuscript. However, throughout the manuscript, the comparison at least is not clearly stated. I would suggest giving a summary or some statements of comparisons on the main properties. Also, how do these data compare to North American forest fires? A brief discussion would put these data sets in a better context for modeling studies or for atmospheric implications.
- What are the aerosol loadings in the aging experiments? At high loading, ozone could readily react with the gases and be lost onto particles, so the observed photochemical aging is mainly by ozone resulting in a low equivalent time (less than 2 days, Table 1)? Please comment on this issue.
Minor comments:
- There are too many abbreviations which lead more confusions and less readability. It would be convenient to have a table or list. Some terms are only used for less than a few times, so it is not necessary to use abbreviations. For example, DMF, MeOH, PRD, etc. Define the variables or abbreviations when they are first used, then use the symbols or abbreviations, duplicated definition is not necessary, for example, L35,36,39, 117,140, 235.
- L28, it would be better to use “determined” than “defined”.
- Figure 3, what do the bottom right squares with lines indicate?
- L669, how do you determine the OC1-4, Pyrol C and EC?
- L509, how was the solubility determined?
- L603-605, Figure 5, I don’t see a clear correlation between EC/OC and MAC if excluding the RWC data.
- L684-685, how does the trend look like if excluding the chamber data? or how does it look like if it is plotted on a log scale?
Citation: https://doi.org/10.5194/egusphere-2025-2759-RC2 -
AC1: 'Comment on egusphere-2025-2759', Arya Mukherjee, 02 Oct 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-2759/egusphere-2025-2759-AC1-supplement.pdf
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-2759', Anonymous Referee #1, 21 Jul 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-2759/egusphere-2025-2759-RC1-supplement.pdf
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RC2: 'Comment on egusphere-2025-2759', Anonymous Referee #2, 18 Aug 2025
This manuscript presents a comprehensive investigation on the emission factors, chemical, and optical properties of organics from Eurasian arctic-boreal and South African savanna biomass combustion in the lab. Brown carbon (BrC) is an important light-absorbing component in aerosol that affects the radiative balance in the atmosphere. The manuscript also investigated the effects of atmospheric dilution and aging on the optical properties of BrC. There are two comments that I wish the authors can address in the revision.
General comments:
- It is stated in the abstract and conclusions that the comparison with African savanna biomass is an objective of this manuscript. However, throughout the manuscript, the comparison at least is not clearly stated. I would suggest giving a summary or some statements of comparisons on the main properties. Also, how do these data compare to North American forest fires? A brief discussion would put these data sets in a better context for modeling studies or for atmospheric implications.
- What are the aerosol loadings in the aging experiments? At high loading, ozone could readily react with the gases and be lost onto particles, so the observed photochemical aging is mainly by ozone resulting in a low equivalent time (less than 2 days, Table 1)? Please comment on this issue.
Minor comments:
- There are too many abbreviations which lead more confusions and less readability. It would be convenient to have a table or list. Some terms are only used for less than a few times, so it is not necessary to use abbreviations. For example, DMF, MeOH, PRD, etc. Define the variables or abbreviations when they are first used, then use the symbols or abbreviations, duplicated definition is not necessary, for example, L35,36,39, 117,140, 235.
- L28, it would be better to use “determined” than “defined”.
- Figure 3, what do the bottom right squares with lines indicate?
- L669, how do you determine the OC1-4, Pyrol C and EC?
- L509, how was the solubility determined?
- L603-605, Figure 5, I don’t see a clear correlation between EC/OC and MAC if excluding the RWC data.
- L684-685, how does the trend look like if excluding the chamber data? or how does it look like if it is plotted on a log scale?
Citation: https://doi.org/10.5194/egusphere-2025-2759-RC2 -
AC1: 'Comment on egusphere-2025-2759', Arya Mukherjee, 02 Oct 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-2759/egusphere-2025-2759-AC1-supplement.pdf
Peer review completion
Journal article(s) based on this preprint
Data sets
Data files for Biomass Burning Experiments for manuscript Arya Mukherjee https://doi.org/10.5281/zenodo.15647186
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Arya Mukherjee
Anni Hartikainen
Markus Somero
Viljami Luostari
Mika Ihalainen
Christopher P. Rüger
Timo Kekäläinen
Ville H. Nissinen
Luis M. F. Barreira
Hanna Koponen
Tuukka Kokkola
Delun Li
Lejish Vettikkat
Pasi Yli-Pirilä
Muhammad Shahzaib
Meri M. Ruppel
Ville Vakkari
Kerneels Jaars
Stefan J. Siebert
Angela Buchholz
Kajar Köster
Pieter G. van Zyl
Hilkka Timonen
Niko Kinnunen
Janne Jänis
Annele Virtanen
Aki Virkkula
Olli Sippula
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(2344 KB) - Metadata XML
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Supplement
(1863 KB) - BibTeX
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- Final revised paper