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.