the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 27 Jan 2025
Formation and composition of organic aerosols from the uptake of glyoxal on natural mineral dust aerosols: a laboratory study
Abstract. The uptake of glyoxal on realistic submicron mineral dust aerosol particles from a natural soil (Gobi Desert) is investigated during experiments in a large simulation chamber, under variable experimental conditions of relative humidity, irradiation, and ozone concentrations. The uptake of glyoxal on the dust particles starts as soon as the glyoxal is injected in the chamber. At 80 % RH, the measured uptake coefficient of glyoxal on mineral dust is γ = (9 ± 5) × 10⁻³. The totality of the mass of reacting glyoxal is transformed in organic matter on the surface of the dust particles. The uptake of glyoxal is accompanied by the appearance marker peaks in the organic mass spectra and a persistent growth in the volume concentration of the dust particles. While the mass of the organic matter on the dust rapidly reverts to values prior to uptake, the organic composition of the dust is modified irreversibly. Glycolic and other organic acids but also oligomers are detected on the dust. At 80 % RH, compounds ranging from C4 to C10 are observed as oligomerization products of glyoxal mono- and di-hydrate forms. The study suggests that dust aerosols could play a very substantial role in the formation of organic aerosols at high relative humidity, but also that the reaction could have potential important implications for the dust optical and hygroscopic properties, including their pH.
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Status: closed
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RC1: 'Comment on egusphere-2024-4073', Anonymous Referee #1, 14 Feb 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4073/egusphere-2024-4073-RC1-supplement.pdf
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AC1: 'Reply on RC1', Paola Formenti, 15 Jun 2025
The authors are grateful to anonymous reviewer 1 and 2 for providing very valuable feedbacks to the manuscript. Our detailed point-by-point response to their comments are reported below.
Both referees, implicitly or explicitly, indicated that the manuscript was presenting too many details, which were hampering the understanding the main conclusions and novelties of the research. To overcome this issue, we have reorganized the manuscript as follows
- A significant part of the experimental section is now reported in the supplementary material, only the major details remain in the main text
- The “results and discussion” section has been separated to highlight the implications of the results
- The detailed discussion of the mass spectra in the composition section has been moved in the supplementary material, to highlight the discussion on the formation of acids and oligomers
We believe that these significant modifications improved the reading and the understanding of the manuscript, fostering its significance.
The point by point reponse to the Referee’ remarks and questions are in the supplement.
Best regards. P Formenti
-
AC1: 'Reply on RC1', Paola Formenti, 15 Jun 2025
-
RC2: 'Comment on egusphere-2024-4073', Anonymous Referee #2, 05 Mar 2025
General comments:
This manuscript presents a well-designed laboratory study investigating the uptake of glyoxal on natural mineral dust aerosols from the Gobi Desert. The authors utilize a large simulation chamber to explore the formation of organic aerosols (OA) under varying atmospheric conditions, including different relative humidity (RH) levels and the presence of ozone. The study provides important experimental constraints on glyoxal uptake coefficients and highlights the role of mineral dust in heterogeneous atmospheric chemistry.Major Comments:
1. Scientific Significance and Novelty
The study provides valuable insights into the uptake of glyoxal on mineral dust, yet the novelty should be more explicitly stated. How does this work go beyond previous studies such as Shen et al. (2016) or Zogka et al. (2024)? A clearer articulation of the key new findings would strengthen the introduction.
2. Mechanistic Understanding of Organic Aerosol Formation
The paper suggests that organic aerosol (OA) formation from glyoxal uptake on dust is significant, yet the reversibility of the process raises questions about its atmospheric relevance. Can the authors discuss potential mechanisms for OA stabilization under ambient conditions (e.g., secondary reactions, coagulation)?
3. Uncertainty in Uptake Coefficients
The reported uptake coefficient (γ = 9 × 10-3 ± 5) shows large variability. Given the importance of γ in atmospheric modeling, can the authors provide a sensitivity analysis on key parameters (e.g., dust surface area, chamber conditions)? How do wall losses impact the measured γ values?
4. Role of Relative Humidity and Surface Chemistry
The data indicate a strong dependence of glyoxal uptake on relative humidity (RH), but the underlying reasons are not fully explored. Is this due to enhanced solubility, surface adsorption, or heterogeneous reactions? Additional discussion on the molecular-level processes involved would improve clarity.
5. Optical and Hygroscopic Property Changes
The study mentions that glyoxal uptake modifies dust properties, yet quantitative data on optical and hygroscopic changes are limited. Can the authors provide experimental evidence (e.g., changes in scattering, hygroscopic growth factors) to support these claims?Minor Comments:
1. Experimental Controls and Reproducibility
While the authors conducted control experiments with ammonium sulfate, it is unclear whether repeated experiments were performed to assess reproducibility. Were there significant variations across trials, and how were they addressed?
2. Data Interpretation in Figure 1 and Figure 2
The time series data suggest transient organic aerosol formation, followed by evaporation. Could this be due to chamber dilution effects rather than desorption? A more detailed discussion would clarify the interpretation.
3. Chemical Characterization of Oligomers
The study identifies C4–C10 oligomers but does not provide detailed structural assignments. Were tandem MS (MS/MS) or other advanced techniques used to confirm molecular identities? If not, adding structural information would strengthen the findings.
4. Comparison with Atmospheric Conditions
The chamber experiments are performed at controlled conditions, but how do these findings translate to real atmospheric environments? Discussion on differences in dust properties, glyoxal concentrations, and timescales in the ambient atmosphere would be beneficial.-
AC2: 'Reply on RC2', Paola Formenti, 15 Jun 2025
The authors are grateful to anonymous reviewer 1 and 2 for providing very valuable feedbacks to the manuscript. Our detailed point-by-point response to their comments are reported below.
Both referees, implicitly or explicitly, indicated that the manuscript was presenting too many details, which were hampering the understanding the main conclusions and novelties of the research. To overcome this issue, we have reorganized the manuscript as follows
- A significant part of the experimental section is now reported in the supplementary material, only the major details remain in the main text
- The “results and discussion” section has been separated to highlight the implications of the results
- The detailed discussion of the mass spectra in the composition section has been moved in the supplementary material, to highlight the discussion on the formation of acids and oligomers
We believe that these significant modifications improved the reading and the understanding of the manuscript, fostering its significance.
The point by point reponse to the Referee’ remarks and questions are in the supplement.
Best regards. P Formenti
-
AC2: 'Reply on RC2', Paola Formenti, 15 Jun 2025
Status: closed
-
RC1: 'Comment on egusphere-2024-4073', Anonymous Referee #1, 14 Feb 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4073/egusphere-2024-4073-RC1-supplement.pdf
-
AC1: 'Reply on RC1', Paola Formenti, 15 Jun 2025
The authors are grateful to anonymous reviewer 1 and 2 for providing very valuable feedbacks to the manuscript. Our detailed point-by-point response to their comments are reported below.
Both referees, implicitly or explicitly, indicated that the manuscript was presenting too many details, which were hampering the understanding the main conclusions and novelties of the research. To overcome this issue, we have reorganized the manuscript as follows
- A significant part of the experimental section is now reported in the supplementary material, only the major details remain in the main text
- The “results and discussion” section has been separated to highlight the implications of the results
- The detailed discussion of the mass spectra in the composition section has been moved in the supplementary material, to highlight the discussion on the formation of acids and oligomers
We believe that these significant modifications improved the reading and the understanding of the manuscript, fostering its significance.
The point by point reponse to the Referee’ remarks and questions are in the supplement.
Best regards. P Formenti
-
AC1: 'Reply on RC1', Paola Formenti, 15 Jun 2025
-
RC2: 'Comment on egusphere-2024-4073', Anonymous Referee #2, 05 Mar 2025
General comments:
This manuscript presents a well-designed laboratory study investigating the uptake of glyoxal on natural mineral dust aerosols from the Gobi Desert. The authors utilize a large simulation chamber to explore the formation of organic aerosols (OA) under varying atmospheric conditions, including different relative humidity (RH) levels and the presence of ozone. The study provides important experimental constraints on glyoxal uptake coefficients and highlights the role of mineral dust in heterogeneous atmospheric chemistry.Major Comments:
1. Scientific Significance and Novelty
The study provides valuable insights into the uptake of glyoxal on mineral dust, yet the novelty should be more explicitly stated. How does this work go beyond previous studies such as Shen et al. (2016) or Zogka et al. (2024)? A clearer articulation of the key new findings would strengthen the introduction.
2. Mechanistic Understanding of Organic Aerosol Formation
The paper suggests that organic aerosol (OA) formation from glyoxal uptake on dust is significant, yet the reversibility of the process raises questions about its atmospheric relevance. Can the authors discuss potential mechanisms for OA stabilization under ambient conditions (e.g., secondary reactions, coagulation)?
3. Uncertainty in Uptake Coefficients
The reported uptake coefficient (γ = 9 × 10-3 ± 5) shows large variability. Given the importance of γ in atmospheric modeling, can the authors provide a sensitivity analysis on key parameters (e.g., dust surface area, chamber conditions)? How do wall losses impact the measured γ values?
4. Role of Relative Humidity and Surface Chemistry
The data indicate a strong dependence of glyoxal uptake on relative humidity (RH), but the underlying reasons are not fully explored. Is this due to enhanced solubility, surface adsorption, or heterogeneous reactions? Additional discussion on the molecular-level processes involved would improve clarity.
5. Optical and Hygroscopic Property Changes
The study mentions that glyoxal uptake modifies dust properties, yet quantitative data on optical and hygroscopic changes are limited. Can the authors provide experimental evidence (e.g., changes in scattering, hygroscopic growth factors) to support these claims?Minor Comments:
1. Experimental Controls and Reproducibility
While the authors conducted control experiments with ammonium sulfate, it is unclear whether repeated experiments were performed to assess reproducibility. Were there significant variations across trials, and how were they addressed?
2. Data Interpretation in Figure 1 and Figure 2
The time series data suggest transient organic aerosol formation, followed by evaporation. Could this be due to chamber dilution effects rather than desorption? A more detailed discussion would clarify the interpretation.
3. Chemical Characterization of Oligomers
The study identifies C4–C10 oligomers but does not provide detailed structural assignments. Were tandem MS (MS/MS) or other advanced techniques used to confirm molecular identities? If not, adding structural information would strengthen the findings.
4. Comparison with Atmospheric Conditions
The chamber experiments are performed at controlled conditions, but how do these findings translate to real atmospheric environments? Discussion on differences in dust properties, glyoxal concentrations, and timescales in the ambient atmosphere would be beneficial.-
AC2: 'Reply on RC2', Paola Formenti, 15 Jun 2025
The authors are grateful to anonymous reviewer 1 and 2 for providing very valuable feedbacks to the manuscript. Our detailed point-by-point response to their comments are reported below.
Both referees, implicitly or explicitly, indicated that the manuscript was presenting too many details, which were hampering the understanding the main conclusions and novelties of the research. To overcome this issue, we have reorganized the manuscript as follows
- A significant part of the experimental section is now reported in the supplementary material, only the major details remain in the main text
- The “results and discussion” section has been separated to highlight the implications of the results
- The detailed discussion of the mass spectra in the composition section has been moved in the supplementary material, to highlight the discussion on the formation of acids and oligomers
We believe that these significant modifications improved the reading and the understanding of the manuscript, fostering its significance.
The point by point reponse to the Referee’ remarks and questions are in the supplement.
Best regards. P Formenti
-
AC2: 'Reply on RC2', Paola Formenti, 15 Jun 2025
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