Measurement report: Characteristics of aminiums in PM<sub>2.5</sub> during winter clean and polluted episodes in China: aminium outbreak and its constraint

Xu, Yu; Liu, Tang; Ma, Yi-Jia; Sun, Qi-Bin; Xiao, Hong-Wei; Xiao, Hao; Xiao, Hua-Yun

doi:https://doi.org/10.5194/egusphere-2024-975

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https://doi.org/10.5194/egusphere-2024-975

Preprints

03 May 2024

| 03 May 2024

Measurement report: Characteristics of aminiums in PM_2.5 during winter clean and polluted episodes in China: aminium outbreak and its constraint

Yu Xu, Tang Liu, Yi-Jia Ma, Qi-Bin Sun, Hong-Wei Xiao, Hao Xiao, and Hua-Yun Xiao

Abstract. Amines and aminiums play an important role in particle formation, liquid-phase reactions, and climate change, attracting considerable attention over the years. Here, we investigated the concentrations and compositions of aminiums in PM_2.5 in 11 Chinese cities during the winter, focusing on the characteristics of aminiums during the polluted days and the key factors influencing aminium outbreak. Monomethylaminium was the dominant aminium species in most cities excepting Taiyuan and Guangzhou, followed by dimethylaminium. Diethylaminium dominated the total aminiums in Taiyuan and Guangzhou. Thus, the main amine sources in Taiyuan and Guangzhou were significantly different from those in other cities. The concentrations of the total aminiums (TA) in all cities increased significantly during the polluted days, with weak aminium outbreaks in Xi'an and Beijing. Additionally, the concentrations of TA in Xi'an and Beijing were insignificantly correlated with those of PM_2.5 and the major acidic aerosol components, while the opposite pattern was observed in 9 other cities. Thus, acid-base chemistry was significantly associated with the formation of aminiums in PM_2.5 in all cities excepting Xi'an and Beijing. Based on the sensitivity analysis of the aminiums/ammonium ratio to ammonium changes as well as excluding the effects of relative humidity and atmospheric oxidation, we proposed the possibility of the competitive uptake of ammonia versus amines on acidic aerosols or the displacement of aminiums by ammonia in Xi'an and Beijing (constraining aminium outbreaks). Overall, this study deepens the understanding of the spatiotemporal differences in aminium characteristic and formation in China. However, the uptake of amines on particles to form aminiums and the relevant influencing factors require further mechanistic research.

Received: 31 Mar 2024 – Discussion started: 03 May 2024

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23 Sep 2024

Measurement report: Occurrence of aminiums in PM_2.5 during winter in China – aminium outbreak during polluted episodes and potential constraints

Yu Xu, Tang Liu, Yi-Jia Ma, Qi-Bin Sun, Hong-Wei Xiao, Hao Xiao, Hua-Yun Xiao, and Cong-Qiang Liu

Atmos. Chem. Phys., 24, 10531–10542, https://doi.org/10.5194/acp-24-10531-2024,https://doi.org/10.5194/acp-24-10531-2024, 2024

Short summary

Yu Xu, Tang Liu, Yi-Jia Ma, Qi-Bin Sun, Hong-Wei Xiao, Hao Xiao, and Hua-Yun Xiao

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2024-975', Anonymous Referee #1, 22 May 2024

The manuscript entitled "Measurement report: Characteristics of aminiums in PM_2.5 during winter clean and polluted episodes in China: aminium outbreak and its constraint" presents the pollution characteristics of amine organic compounds in PM_2.5 in 11 regions of China. It focuses on the comparative analysis of clean and polluted days. While the study has certain scientific significance, the analysis and discussion part of the study is not in-depth enough, and there are still some problems that the author needs to further answer or improve.
Q1: The English writing of the article required modification prior to publication. The text contained numerous descriptions that were overly complex, rendering them opaque and indirect. For example, Lines 175-179.
Q2: The whole study only analyzes and explores the correlation and ratio relationship between regions and components. The reasons for the clarification need to be further demonstrated. There is no analysis of the mechanism relationship between amines and particulate matter, and much experimental literature has been studied.
Q3: The article only stays at the level of analyzing phenomena. The organic amines on the filter membrane are still aged particulate organic matter. The results are not accurate enough for source estimation using correlation and ratio.
Q4: The article mentions that the XA and BJ sampling sites differ more than others. The reason should be compared and analyzed to recent 2-3 years of literature on the source of air pollution. And while Figure 5 of the article only shows the correlation of NH₄⁺ with NO₃^—, SO₄^2-, and total organic acids in XA and BJ, how does a clean day compare to a polluted day?
Q5: Line 20-122, please accurately describe the sampling times for particulate filters.
Q6: Line 250-251: Figure 4 does not reflect the different seasons, please correct this.
Q7: Line 251-257: The conclusions of the presentation in this paragraph are comparable to those of the previous study. It would be beneficial to include the data from the previous research results in a comparison in the figure.
Q8: Line 311-312: This passage has illustrated the inadequacy of traditional correlation analysis to account for research discrepancies. Moreover, the subsequent conclusions have not been further explored in terms of new methods.
Q9: Line 319-322: The text is ambiguous. What is the author's intention here?
Q10: Line 359-360: Is it accurate to discuss atmospheric oxidation here and compare it with the average values? It is suggested that the changing trend of amine pollution level and atmospheric oxidation level should be further analyzed.
Q11: Line 394-402: This paragraph is analyzed using the ratio relationship between total amines and ammonium salts. Is there a literature reference for this conclusion? Please add literature for further clarification.
Q12: This paper discusses that although the component characteristics of TY and GZ areas are similar, there are great differences according to the scatter diagram. What are the reasons for the differences?

Citation: https://doi.org/10.5194/egusphere-2024-975-RC1
- AC1: 'Reply on RC1', Yu Xu, 10 Jul 2024
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-975/egusphere-2024-975-AC1-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2024-975-AC1
RC2:
'Comment on egusphere-2024-975', Anonymous Referee #2, 16 Jun 2024
This work presents the measurements of aminiums in PM_2.5 collected from 11 cities in China during winter, and compares their characteristics and chemistry between the clean and polluted periods to investigate the key factors influencing the aminium outbreak during the polluted periods. The authors suggested that the competitive uptake of ammonia versus amines on acidic aerosols and/or the displacement of aminiums by ammonia in ambient aerosols are the key to limiting aminium outbreaks. I find this to be a useful contribution to the literature to advance knowledge about amines. Indeed, amines (/aminiums) are important in many aspects of atmospheric chemistry. These datasets are valuable for amine-related chemistry in the atmosphere. In general, the paper is well written, and this reviewer recommends its publication after addressing the following minor comments.
Specific comments:
The aliphatic amines are typically in the gas-phase, thus their presence in aerosol particles should be attributable to acid-base chemistry and/or other processes. This implies that all aminiums reported here were predominantly formed through secondary processes. In discussing sources, you refer to the sources of gas-phase amines. It is important to highlight that these gas-phase amines from diverse sources are mainly partitioned into the particle phase through secondary processes. This should be clear.

Line 232: Significant figures should be unified.

RH is another important factor affecting the formation of aliphatic aminiums in addition to acidity. This should be considered.

Line 301: Please consider using a more suitable word instead of “roughly”.

Lines 363‒366: Please rephrase the sentence.

Regarding the sensitivity analysis of the aminiums/ammonium ratio to ammonium changes, the results presented here are very intuitive and interesting. Have similar comparisons been made in previous studies? Alternatively, can the datasets be compared with previous observations?

Lines 433‒435: Please rephrase this part. For example, “The concentrations, compositions, and temporal and spatial variations of aminiums in PM2.5 in 11 different Chinese cities during the winter were systematically investigated to reveal the key factors affecting the aminium outbreak during the polluted days”

The author has proposed some meaningful conclusions based on field observation data, such as “the competitive uptake of ammonia against amines on acidic aerosols in the ambient atmosphere in XA and BJ”. I know that the atmospheric environment in the real world is very complex, so the author should point out in the article that further laboratory validation experiments for this conclusion or long-term observation studies in high ammonia and low amine environments are necessary in future research.

Lines 473‒477: The author should point out that the occurrence of this situation may lead to an insignificant correlation between aminiums and indicators in the particle phase.
Citation: https://doi.org/10.5194/egusphere-2024-975-RC2
- AC2: 'Reply on RC2', Yu Xu, 10 Jul 2024
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-975/egusphere-2024-975-AC2-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2024-975-AC2

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2024-975', Anonymous Referee #1, 22 May 2024

The manuscript entitled "Measurement report: Characteristics of aminiums in PM_2.5 during winter clean and polluted episodes in China: aminium outbreak and its constraint" presents the pollution characteristics of amine organic compounds in PM_2.5 in 11 regions of China. It focuses on the comparative analysis of clean and polluted days. While the study has certain scientific significance, the analysis and discussion part of the study is not in-depth enough, and there are still some problems that the author needs to further answer or improve.
Q1: The English writing of the article required modification prior to publication. The text contained numerous descriptions that were overly complex, rendering them opaque and indirect. For example, Lines 175-179.
Q2: The whole study only analyzes and explores the correlation and ratio relationship between regions and components. The reasons for the clarification need to be further demonstrated. There is no analysis of the mechanism relationship between amines and particulate matter, and much experimental literature has been studied.
Q3: The article only stays at the level of analyzing phenomena. The organic amines on the filter membrane are still aged particulate organic matter. The results are not accurate enough for source estimation using correlation and ratio.
Q4: The article mentions that the XA and BJ sampling sites differ more than others. The reason should be compared and analyzed to recent 2-3 years of literature on the source of air pollution. And while Figure 5 of the article only shows the correlation of NH₄⁺ with NO₃^—, SO₄^2-, and total organic acids in XA and BJ, how does a clean day compare to a polluted day?
Q5: Line 20-122, please accurately describe the sampling times for particulate filters.
Q6: Line 250-251: Figure 4 does not reflect the different seasons, please correct this.
Q7: Line 251-257: The conclusions of the presentation in this paragraph are comparable to those of the previous study. It would be beneficial to include the data from the previous research results in a comparison in the figure.
Q8: Line 311-312: This passage has illustrated the inadequacy of traditional correlation analysis to account for research discrepancies. Moreover, the subsequent conclusions have not been further explored in terms of new methods.
Q9: Line 319-322: The text is ambiguous. What is the author's intention here?
Q10: Line 359-360: Is it accurate to discuss atmospheric oxidation here and compare it with the average values? It is suggested that the changing trend of amine pollution level and atmospheric oxidation level should be further analyzed.
Q11: Line 394-402: This paragraph is analyzed using the ratio relationship between total amines and ammonium salts. Is there a literature reference for this conclusion? Please add literature for further clarification.
Q12: This paper discusses that although the component characteristics of TY and GZ areas are similar, there are great differences according to the scatter diagram. What are the reasons for the differences?

Citation: https://doi.org/10.5194/egusphere-2024-975-RC1
- AC1: 'Reply on RC1', Yu Xu, 10 Jul 2024
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-975/egusphere-2024-975-AC1-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2024-975-AC1
RC2:
'Comment on egusphere-2024-975', Anonymous Referee #2, 16 Jun 2024
This work presents the measurements of aminiums in PM_2.5 collected from 11 cities in China during winter, and compares their characteristics and chemistry between the clean and polluted periods to investigate the key factors influencing the aminium outbreak during the polluted periods. The authors suggested that the competitive uptake of ammonia versus amines on acidic aerosols and/or the displacement of aminiums by ammonia in ambient aerosols are the key to limiting aminium outbreaks. I find this to be a useful contribution to the literature to advance knowledge about amines. Indeed, amines (/aminiums) are important in many aspects of atmospheric chemistry. These datasets are valuable for amine-related chemistry in the atmosphere. In general, the paper is well written, and this reviewer recommends its publication after addressing the following minor comments.
Specific comments:
The aliphatic amines are typically in the gas-phase, thus their presence in aerosol particles should be attributable to acid-base chemistry and/or other processes. This implies that all aminiums reported here were predominantly formed through secondary processes. In discussing sources, you refer to the sources of gas-phase amines. It is important to highlight that these gas-phase amines from diverse sources are mainly partitioned into the particle phase through secondary processes. This should be clear.

Line 232: Significant figures should be unified.

RH is another important factor affecting the formation of aliphatic aminiums in addition to acidity. This should be considered.

Line 301: Please consider using a more suitable word instead of “roughly”.

Lines 363‒366: Please rephrase the sentence.

Regarding the sensitivity analysis of the aminiums/ammonium ratio to ammonium changes, the results presented here are very intuitive and interesting. Have similar comparisons been made in previous studies? Alternatively, can the datasets be compared with previous observations?

Lines 433‒435: Please rephrase this part. For example, “The concentrations, compositions, and temporal and spatial variations of aminiums in PM2.5 in 11 different Chinese cities during the winter were systematically investigated to reveal the key factors affecting the aminium outbreak during the polluted days”

The author has proposed some meaningful conclusions based on field observation data, such as “the competitive uptake of ammonia against amines on acidic aerosols in the ambient atmosphere in XA and BJ”. I know that the atmospheric environment in the real world is very complex, so the author should point out in the article that further laboratory validation experiments for this conclusion or long-term observation studies in high ammonia and low amine environments are necessary in future research.

Lines 473‒477: The author should point out that the occurrence of this situation may lead to an insignificant correlation between aminiums and indicators in the particle phase.
Citation: https://doi.org/10.5194/egusphere-2024-975-RC2
- AC2: 'Reply on RC2', Yu Xu, 10 Jul 2024
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-975/egusphere-2024-975-AC2-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2024-975-AC2

Peer review completion

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

AR by Yu Xu on behalf of the Authors (10 Jul 2024) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (23 Jul 2024) by Roya Bahreini

RR by Anonymous Referee #2 (30 Jul 2024)

RR by Anonymous Referee #3 (03 Aug 2024)

Suggestions for revision or reasons for rejection

This paper summarizes results from observations of aminium species in PM2.5 aerosols at 11 cities in China, in different regions which experience different meteorology and pollution sources. They identify momomethylaminium, dimethylaminium, and diethyaminium as the dominant species. Their observations demonstrate higher concentrations of aminium species under higher PM2.5 levels and typically at higher concentrations of acidic aerosol components, suggesting gas to particle partitioning and subsequent acid-base reactions as the main mechanism for aerosol aminium. In some cities, relative humidity and ammonium concentrations appear to control the extent of uptake. The observations are valuable and the content fit a Measurement Report. The authors need to address the following comments before the paper is accepted for publication.
1. line 199-200: The higher the Henry’s law constant, the more soluble the gas is and higher its partitioning to the aqueous phase. Are the indicated values correct? If so, DEA is the most soluble aminium.
2. There is a large variability in the reported concentrations of aminium and its ratios to ammonium. Can you please include some statistical analysis to examine if the observed differences in the average concentrations on the polluted vs. clean days significant or not?
3. I’m curious why the extent of acidity is defined with 2 times the concentration of sulfate. I believe it’s common to calculate acidity (H+) in molar space for which the molar concentrations of H+ associated with sulfate includes the factor of 2 due to its charge balance, but I don’t think multiplying the mass concentration by 2 makes sense. Also in Fig. S3 why aren’t the organic acids included?
4. Line 391: atmospheric oxidation would be a loss pattern for aminium precursors so it’s strange to mention this loss process as a possibility to explain the larger concentrations of aminium in aerosols.
5. figure 4 (and other similar figures): need to add a size legend
6. I have several editorial suggestions listed below:
- line 30,39: change “excepting” to “except”
- line 116-117: consider deleting either obviously or inevitably
- line 154: change “determination” to “detection”
- line 304: change “revealed” to “discussed”
- Line 330: “can largely be derived”
- Line 445: change “extraction ratio” to “ratio”
- line 494-498: Modify to “Although a recent study has also demonstrated the possibility of individual aminium species being displaced by ammonia in an environment of high ammonia level (Chen et al., 2022a), the uptake of amines on particles to form aminiums and the mechanisms of relevant influencing factors are still not fully understood”.
- line 507: change “in particular” to “In addition”

Hide

ED: Publish subject to minor revisions (review by editor) (03 Aug 2024) by Roya Bahreini

AR by Yu Xu on behalf of the Authors (05 Aug 2024) Author's response Author's tracked changes Manuscript

ED: Publish subject to minor revisions (review by editor) (08 Aug 2024) by Roya Bahreini

AR by Yu Xu on behalf of the Authors (08 Aug 2024) Author's response Author's tracked changes Manuscript

ED: Publish as is (09 Aug 2024) by Roya Bahreini

AR by Yu Xu on behalf of the Authors (10 Aug 2024) Manuscript

Journal article(s) based on this preprint

23 Sep 2024

Measurement report: Occurrence of aminiums in PM_2.5 during winter in China – aminium outbreak during polluted episodes and potential constraints

Yu Xu, Tang Liu, Yi-Jia Ma, Qi-Bin Sun, Hong-Wei Xiao, Hao Xiao, Hua-Yun Xiao, and Cong-Qiang Liu

Atmos. Chem. Phys., 24, 10531–10542, https://doi.org/10.5194/acp-24-10531-2024,https://doi.org/10.5194/acp-24-10531-2024, 2024

Short summary

Yu Xu, Tang Liu, Yi-Jia Ma, Qi-Bin Sun, Hong-Wei Xiao, Hao Xiao, and Hua-Yun Xiao

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https://doi.org/10.5194/egusphere-2024-975-supplement

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Measurement report: Measurement report: Characteristics of aminiums in PM2.5 during winter clean and polluted episodes in China: aminium outbreak and its constraint Yu Xu, Tang Liu, Yi-Jia Ma, Qi-Bin Sun, Hong-Wei Xiao, Hao Xiao, and Hua-Yun Xiao https://doi.org/10.5281/zenodo.11102019

Yu Xu, Tang Liu, Yi-Jia Ma, Qi-Bin Sun, Hong-Wei Xiao, Hao Xiao, and Hua-Yun Xiao

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This study has explored the characteristics of aminiums, ammonium, and PM_2.5 from the clean days to the polluted days according to the observational data from 11 different Chinese cities, highlighting the possibility of the competitive uptake of ammonia versus amines on acidic aerosols, or the displacement of aminiums by ammonia under a high ammonia condition. The overall results deepen the understanding of the spatiotemporal differences in aminium characteristic and formation in China.


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