Concentration and size distribution of black carbon over the ablation area of Potanin glacier: Enrichment ability of surface weathering granular ice of water-insoluble particles with snow/ice melting

Ueda, Sayako; Sakai, Akiko; Ohata, Sho; Khalzan, Purevdagva; Matoba, Sumito; Kondo, Ken; Matsui, Hitoshi

doi:10.5194/egusphere-2025-5301

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https://doi.org/10.5194/egusphere-2025-5301

Preprints

12 Nov 2025

| 12 Nov 2025

Concentration and size distribution of black carbon over the ablation area of Potanin glacier: Enrichment ability of surface weathering granular ice of water-insoluble particles with snow/ice melting

Sayako Ueda, Akiko Sakai, Sho Ohata, Purevdagva Khalzan, Sumito Matoba, Ken Kondo, and Hitoshi Matsui

Abstract. Light-absorbing particles on surface ice in ablation areas can accelerate glacier melting and shrinkage. A Single Soot Particle Photometer was used to measure black carbon (BC) mass concentrations (M_BC) in the ablation area of Potanin Glacier, Mongolia during summer. Surface-ice M_BC values (42–555 ng g^-¹) greatly exceeded those of surface snow (5–22 ng g^-¹), snow and rain (2–6 ng g^-¹), and surface melt water (2–11 ng g^-¹). Vertical profiles of M_BC revealed high surface-layer concentrations, suggesting impurities trapped in the granular ice: the particularly low-density layer on the surface of the weathering crust. In the ablation area, M_BC values of granular ice decreased with lower elevation: 134–601 ng g^-1 at 3317 m site and 8–96 ng g^-1 at 3078 m site. The fraction of residual surface BC to BC contained in lost water over a year, R was calculated using the yearly BC deposition flux and water ablation weight A_w. Average R values were 0.17 and 0.011, respectively, at 3317 m and 3078 m. A_w were 246 g w.e. cm^-2 and 325 g w.e. cm^-2, suggesting that the granular ice retains BC particles best in the upstream ablation area, showing concomitantly less capability with increasing ablation. Enriched BC on the ablation area surface comprises recent BC deposits and BC from the glacier's lower layer after rising during decades or more. Those BC emissions and deposits can therefore affect both future and present ablation area melting processes.

Received: 27 Oct 2025 – Discussion started: 12 Nov 2025

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Journal article(s) based on this preprint

03 Mar 2026

Concentration and size distribution of black carbon over the ablation area of Potanin glacier: enrichment ability of surface weathering granular ice of water-insoluble particles with snow/ice melting

Sayako Ueda, Akiko Sakai, Sho Ohata, Purevdagva Khalzan, Sumito Matoba, Ken Kondo, and Hitoshi Matsui

Atmos. Chem. Phys., 26, 3167–3184, https://doi.org/10.5194/acp-26-3167-2026,https://doi.org/10.5194/acp-26-3167-2026, 2026

Short summary

Sayako Ueda, Akiko Sakai, Sho Ohata, Purevdagva Khalzan, Sumito Matoba, Ken Kondo, and Hitoshi Matsui

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2025-5301', Anonymous Referee #1, 23 Nov 2025
This study investigated the black carbon (BC) mass concentration (MBC) in snow and ice samples from the ablation area of Potanin Glacier in Mongolia during the summers of 2022, 2023, and 2024. Also, this study discussed the distribution characteristics and potential mechanisms of black carbon at different altitudes and depths. This is important for understanding the deposition of black carbon in the cryosphere and climate effects. There are some details that need to be modified, as follows:
2 BC measurement using a nebulizer–SP2 system: Does dust or iron affect the determination of BC by SP2? This needs to be clearly pointed out.

3 Mineral dust and water-insoluble organic matter: how to obtain the mass of dust? Also from Takeuchi and Li (2008)? Necessary introduction is needed.

Lines 200-207, “However, such an order change of mass concentration with altitude was not found for mineral dust or for organic matter.”: This conclusion is unclear. Dust seems to have no downward trend, but OM is also on a downward trend. Also, it needs to be clarified whether it specifically refers to filled, open, or slash results in Fig. 4.

Lines 230-235, and Fig. 5: The figure shows that there are mega black carbons with diameter above 1000 nm, which is rare in atmospheric aerosol research. In addition, you also mentioned that the distribution is wider, which also suggested mega black carbon. I am not questioning your measurement, but I believe it is an important discovery.

Figure 5 is not clear. There seems to be a dotted line, but you haven't explained what the dotted line is.

Lines 259-261 “However, the BC size distributions of surface water and surface ice were similar; the dependence of BC flow out was unclear.”: It is not clear or easy for readers to understand. Besides, what is “Related to the former reason”? It is also not clear.

Line 262: What is 50 nm in Figure 6a? Or is it a typo of 500 nm?

Line 267, “Although their shape is similar to that of soot, the individual spherules in the aggregation had a larger diameter (>100 nm) and were O-rich compared to soot, indicating organics”: Why can't it be a mixture of OM and Soot, add relevant literature, such as iScience 26, 108125, (2023), 10.1016/j.isci.2023.108125. npj Climate and Atmospheric Science 7, 65, (2024), 10.1038/s41612-024-00610-8.

“However, in general, submicrometer atmospheric aerosols are rarely composed only of such organics or mineral dust in internal mixed states”: This sentence is not scientific enough. You prepared the TEM sample through water and cannot compare it with the mixing state of atmospheric aerosols.

1.3 BC size distributions and particle mixing states: The author seems to emphasize the impact of coagulation on particle size distribution, and hopes to explain the differences in black carbon relative to atmospheric aerosols. Unfortunately, the role of the coagulation mechanism has not been clearly explained or involved in data analysis or discussion. Add the latest references, and reconstruct this section to improve readability and the scientific nature of the discussion, i.e., Nature Communications 16, (2025), 10.1038/s41467-025-65079-2. Geophysical Research Letters 46, 8453-8463, (2019), 10.1029/2019gl083171.

Figure 10: Why is there a downward trend of 2023 in Figure (a)? Also, at the same altitude, only one sample was collected in 2023?
Citation: https://doi.org/10.5194/egusphere-2025-5301-RC1
- AC1: 'Reply on RC1', Sayako Ueda, 05 Feb 2026
  
  We appreciate the many constructive comments offered by anonymous reviewer #1, which have improved our manuscript considerably. We have developed a response in the attached document.
  
  Citation: https://doi.org/10.5194/egusphere-2025-5301-AC1
RC2:
'Comment on egusphere-2025-5301', Anonymous Referee #2, 17 Dec 2025

Ueda et al., 2025 “Concentration and size distribution of black carbon over the ablation area of Potanin glacier: Enrichment ability of surface weathering granular ice of water-insoluble particles with snow/ice melting” presents BC in various materials, snow, ice, and water, which were took from Potanin Glacier. TEM analysis was conducted to investigate fine particle composition of inpurities in snow and ice. They discussed comprehensive observation results of BC deposition, residual, and outflow and estimated BC remaining fration on ice with melt water out flow. This study will contribute to extending understanding of BC dynamics in cryosphere science and more detailed understanding on BC climate effects. The methods and analysis support well the conclusion of this study. There are some parts to be revised.
Major comment
1. F_BC was obtained by CAM-ATRAS to estimate BC remining fraction. The idea is interesting and challenging. However, CAM-ATRAS is a global model with spatial resolustion of 1.9° × 2.5° and I wonder this resolution is sufficient or not for estimation FBC in cases where significant spatial heterogeneity is anticipated, such as in ablation glacial regions.
2. It was difficult to understand the connection between the argument presented at the end of Section 3.1.3 regarding the mixing state of particles and the comparison with atmospheric aerosols. Detailed comments are written in specific comments.
3. Does the explanation of BC enrichment on the snow surface discussed in 3.1.1 and 3.1.2 contradict BC enrichment in melted water discussed in 3.1.3? I think it would be better to organize the discussion again.
Spcific comments
L53: I think either ‘fresh’ or ‘new’ would be fine.
L69: Add more specific methods for sampling method and sample treatment, such as amount of snow sampled, area of the sampling points, melting techniques, etc. Glacier might have a large spatial discrepancy of BC in snow, and strong heating can decrease measured BC concentration by SP2.
L75: Since glaciers are flowing, and sampling points are marked by stakes, does this mean the ground position of the sampling points is changing? If so, wouldn't the amount of snow fall and sediment deposited from surrounding weathered rock change over time?
L90: It is preferable to indicate that a blank field has not been analyzed, such as by labeling it “N.A.,” rather than leaving it blank.
L115: How much air flow rate of the nebulizer?
L124: I can understand sonication is needed to minimize BC wall loss, but I wonder the sonication is really effective to mitigate the possible change of the BC size? If yes, sonication may also change original BC size distribution. If there are appropriate references, it should be added.
L143: Is this a handmade instrument?
L196: 'fresh' may be more accurate than 'fresher'. Please check.
L214: Compared to what is it ‘lower’?
L258: Is there any reference?
L270: I could not understand what this sentence is trying to explain. BC is affected post-deposition process, thus comparison with atmospheric BC is meaningless. In addition, while BC sources are remote site from observation area, mineral dust sources are assumed to be local. What are you trying to explain by bringing up atmospheric conditions from entirely different environments shown in these references? Please reconsider.
L272: As I pointed above, the source of dust is expected to be neighboring exposed rock area. I think that the mineral dust simply emitted from neighboring areas into the air by saltation and sand blast process, and was deposited on the snow and ice surface (just dry deposition).
L274: This sentence also fails to clarify what authors expected to explain and its evidence. Why does the presence of other particles promote BC aggregation? If TEM analysis showed advanced BC aggregation or internal mixing with others in the case of samples rich in minerals or organic, this contradicts previous explanations. Furthermore, considering the nebulizer orifice diameter, the droplets formed during atomization should be quite large. Can the agglomeration occurring within droplets really be ignored for these particle rich samples? In any case, I believe this section of the discussion, including this part, requires reorganizing what authors expected to show and their supporting evidence.

Citation: https://doi.org/10.5194/egusphere-2025-5301-RC2
- AC2: 'Reply on RC2', Sayako Ueda, 05 Feb 2026
  
  We appreciate the many constructive comments offered by anonymous reviewer #2, which have improved our manuscript considerably. We have developed a response in the attached document.
  
  Citation: https://doi.org/10.5194/egusphere-2025-5301-AC2

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2025-5301', Anonymous Referee #1, 23 Nov 2025
This study investigated the black carbon (BC) mass concentration (MBC) in snow and ice samples from the ablation area of Potanin Glacier in Mongolia during the summers of 2022, 2023, and 2024. Also, this study discussed the distribution characteristics and potential mechanisms of black carbon at different altitudes and depths. This is important for understanding the deposition of black carbon in the cryosphere and climate effects. There are some details that need to be modified, as follows:
2 BC measurement using a nebulizer–SP2 system: Does dust or iron affect the determination of BC by SP2? This needs to be clearly pointed out.

3 Mineral dust and water-insoluble organic matter: how to obtain the mass of dust? Also from Takeuchi and Li (2008)? Necessary introduction is needed.

Lines 200-207, “However, such an order change of mass concentration with altitude was not found for mineral dust or for organic matter.”: This conclusion is unclear. Dust seems to have no downward trend, but OM is also on a downward trend. Also, it needs to be clarified whether it specifically refers to filled, open, or slash results in Fig. 4.

Lines 230-235, and Fig. 5: The figure shows that there are mega black carbons with diameter above 1000 nm, which is rare in atmospheric aerosol research. In addition, you also mentioned that the distribution is wider, which also suggested mega black carbon. I am not questioning your measurement, but I believe it is an important discovery.

Figure 5 is not clear. There seems to be a dotted line, but you haven't explained what the dotted line is.

Lines 259-261 “However, the BC size distributions of surface water and surface ice were similar; the dependence of BC flow out was unclear.”: It is not clear or easy for readers to understand. Besides, what is “Related to the former reason”? It is also not clear.

Line 262: What is 50 nm in Figure 6a? Or is it a typo of 500 nm?

Line 267, “Although their shape is similar to that of soot, the individual spherules in the aggregation had a larger diameter (>100 nm) and were O-rich compared to soot, indicating organics”: Why can't it be a mixture of OM and Soot, add relevant literature, such as iScience 26, 108125, (2023), 10.1016/j.isci.2023.108125. npj Climate and Atmospheric Science 7, 65, (2024), 10.1038/s41612-024-00610-8.

“However, in general, submicrometer atmospheric aerosols are rarely composed only of such organics or mineral dust in internal mixed states”: This sentence is not scientific enough. You prepared the TEM sample through water and cannot compare it with the mixing state of atmospheric aerosols.

1.3 BC size distributions and particle mixing states: The author seems to emphasize the impact of coagulation on particle size distribution, and hopes to explain the differences in black carbon relative to atmospheric aerosols. Unfortunately, the role of the coagulation mechanism has not been clearly explained or involved in data analysis or discussion. Add the latest references, and reconstruct this section to improve readability and the scientific nature of the discussion, i.e., Nature Communications 16, (2025), 10.1038/s41467-025-65079-2. Geophysical Research Letters 46, 8453-8463, (2019), 10.1029/2019gl083171.

Figure 10: Why is there a downward trend of 2023 in Figure (a)? Also, at the same altitude, only one sample was collected in 2023?
Citation: https://doi.org/10.5194/egusphere-2025-5301-RC1
- AC1: 'Reply on RC1', Sayako Ueda, 05 Feb 2026
  
  We appreciate the many constructive comments offered by anonymous reviewer #1, which have improved our manuscript considerably. We have developed a response in the attached document.
  
  Citation: https://doi.org/10.5194/egusphere-2025-5301-AC1
RC2:
'Comment on egusphere-2025-5301', Anonymous Referee #2, 17 Dec 2025

Ueda et al., 2025 “Concentration and size distribution of black carbon over the ablation area of Potanin glacier: Enrichment ability of surface weathering granular ice of water-insoluble particles with snow/ice melting” presents BC in various materials, snow, ice, and water, which were took from Potanin Glacier. TEM analysis was conducted to investigate fine particle composition of inpurities in snow and ice. They discussed comprehensive observation results of BC deposition, residual, and outflow and estimated BC remaining fration on ice with melt water out flow. This study will contribute to extending understanding of BC dynamics in cryosphere science and more detailed understanding on BC climate effects. The methods and analysis support well the conclusion of this study. There are some parts to be revised.
Major comment
1. F_BC was obtained by CAM-ATRAS to estimate BC remining fraction. The idea is interesting and challenging. However, CAM-ATRAS is a global model with spatial resolustion of 1.9° × 2.5° and I wonder this resolution is sufficient or not for estimation FBC in cases where significant spatial heterogeneity is anticipated, such as in ablation glacial regions.
2. It was difficult to understand the connection between the argument presented at the end of Section 3.1.3 regarding the mixing state of particles and the comparison with atmospheric aerosols. Detailed comments are written in specific comments.
3. Does the explanation of BC enrichment on the snow surface discussed in 3.1.1 and 3.1.2 contradict BC enrichment in melted water discussed in 3.1.3? I think it would be better to organize the discussion again.
Spcific comments
L53: I think either ‘fresh’ or ‘new’ would be fine.
L69: Add more specific methods for sampling method and sample treatment, such as amount of snow sampled, area of the sampling points, melting techniques, etc. Glacier might have a large spatial discrepancy of BC in snow, and strong heating can decrease measured BC concentration by SP2.
L75: Since glaciers are flowing, and sampling points are marked by stakes, does this mean the ground position of the sampling points is changing? If so, wouldn't the amount of snow fall and sediment deposited from surrounding weathered rock change over time?
L90: It is preferable to indicate that a blank field has not been analyzed, such as by labeling it “N.A.,” rather than leaving it blank.
L115: How much air flow rate of the nebulizer?
L124: I can understand sonication is needed to minimize BC wall loss, but I wonder the sonication is really effective to mitigate the possible change of the BC size? If yes, sonication may also change original BC size distribution. If there are appropriate references, it should be added.
L143: Is this a handmade instrument?
L196: 'fresh' may be more accurate than 'fresher'. Please check.
L214: Compared to what is it ‘lower’?
L258: Is there any reference?
L270: I could not understand what this sentence is trying to explain. BC is affected post-deposition process, thus comparison with atmospheric BC is meaningless. In addition, while BC sources are remote site from observation area, mineral dust sources are assumed to be local. What are you trying to explain by bringing up atmospheric conditions from entirely different environments shown in these references? Please reconsider.
L272: As I pointed above, the source of dust is expected to be neighboring exposed rock area. I think that the mineral dust simply emitted from neighboring areas into the air by saltation and sand blast process, and was deposited on the snow and ice surface (just dry deposition).
L274: This sentence also fails to clarify what authors expected to explain and its evidence. Why does the presence of other particles promote BC aggregation? If TEM analysis showed advanced BC aggregation or internal mixing with others in the case of samples rich in minerals or organic, this contradicts previous explanations. Furthermore, considering the nebulizer orifice diameter, the droplets formed during atomization should be quite large. Can the agglomeration occurring within droplets really be ignored for these particle rich samples? In any case, I believe this section of the discussion, including this part, requires reorganizing what authors expected to show and their supporting evidence.

Citation: https://doi.org/10.5194/egusphere-2025-5301-RC2
- AC2: 'Reply on RC2', Sayako Ueda, 05 Feb 2026
  
  We appreciate the many constructive comments offered by anonymous reviewer #2, which have improved our manuscript considerably. We have developed a response in the attached document.
  
  Citation: https://doi.org/10.5194/egusphere-2025-5301-AC2

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload

AR by Sayako Ueda on behalf of the Authors (05 Feb 2026) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (05 Feb 2026) by Manabu Shiraiwa

RR by Anonymous Referee #1 (08 Feb 2026)

ED: Publish as is (16 Feb 2026) by Manabu Shiraiwa

AR by Sayako Ueda on behalf of the Authors (20 Feb 2026) Manuscript

Journal article(s) based on this preprint

03 Mar 2026

Concentration and size distribution of black carbon over the ablation area of Potanin glacier: enrichment ability of surface weathering granular ice of water-insoluble particles with snow/ice melting

Sayako Ueda, Akiko Sakai, Sho Ohata, Purevdagva Khalzan, Sumito Matoba, Ken Kondo, and Hitoshi Matsui

Atmos. Chem. Phys., 26, 3167–3184, https://doi.org/10.5194/acp-26-3167-2026,https://doi.org/10.5194/acp-26-3167-2026, 2026

Short summary

Sayako Ueda, Akiko Sakai, Sho Ohata, Purevdagva Khalzan, Sumito Matoba, Ken Kondo, and Hitoshi Matsui

Supplement

https://doi.org/10.5194/egusphere-2025-5301-supplement

Sayako Ueda, Akiko Sakai, Sho Ohata, Purevdagva Khalzan, Sumito Matoba, Ken Kondo, and Hitoshi Matsui

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Short summary

Light-absorbing particles on surface ice in ablation areas can accelerate glacier melting and shrinkage. Snow and ice were collected from the ablation area of Potanin Glacier, Mongolia. The BC mass concentration of surface granular ice was much larger than that of fresh snow and surface melted water, suggesting that BC is retained in the granular ice at melting. The retained BC was estimated at 1–17 % of the BC in annual ablated water, composed of fresh deposition and the old glacial ice.


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