Morphological features and water solubility of iron in aged fine aerosol particles over the Indian Ocean

Ueda, Sayako; Iwamoto, Yoko; Taketani, Fumikazu; Liu, Mingxu; Matsui, Hitoshi

doi:https://doi.org/10.5194/egusphere-2023-389

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https://doi.org/10.5194/egusphere-2023-389

Preprints

22 Mar 2023

| 22 Mar 2023

Morphological features and water solubility of iron in aged fine aerosol particles over the Indian Ocean

Sayako Ueda, Yoko Iwamoto, Fumikazu Taketani, Mingxu Liu, and Hitoshi Matsui

Abstract. Atmospheric transport of iron (Fe) in fine anthropogenic aerosol particles is an important route of soluble Fe supply to remote oceans from continental areas. To investigate Fe properties of aerosol particles over remote oceans, we analyzed atmospheric aerosol particles over the Indian Ocean during the research vessel Hakuho Maru KH-18-6 cruise. Aerosol particles collected using a cascade impactor were analyzed using transmission electron microscopy (TEM) with an energy-dispersive X-ray spectrometry analyzer. The particle shape and composition on the sample stage of 0.3–0.8 μm aerodynamic diameter indicated that most particles collected north of the equator were composed mainly of ammonium sulfate. Regarding the particle number fraction, 0.6–3.0 % of particles contained Fe, which mostly co-existed with sulfate. Of those particles, Fe was found 26 % as metal spheres, often co-existing with Al or Si, regarded as fly ash, 14 % as mineral dust, and 7 % as iron oxide aggregations. Water-dialysis analyses of TEM samples indicated that Fe in spherical fly ash was almost entirely insoluble, whereas Fe in the other morphological-typed particles was partly (65 % Fe mass on average) soluble. Global model simulations mostly reproduce observed Fe mass concentrations in PM_2.5 collected using a high-volume air sampler, including their north–south contrast during the cruise. In contrast, a marked difference was found between the simulated mass fractions of Fe mineral sources and the observed Fe types. For example, the model underestimated anthropogenic aluminosilicate Fe contained in matter such as fly ash from coal combustion. Our observations suggest that Fe in particles over remote ocean areas has multiple shapes and minerals, and further suggest that its solubility after aging processes differs depending on their morphological and mineral type. Proper consideration of such Fe types at their sources is necessary for accurate estimation of atmospheric Fe effects on marine biological activity.

Received: 03 Mar 2023 – Discussion started: 22 Mar 2023

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11 Sep 2023

Morphological features and water solubility of iron in aged fine aerosol particles over the Indian Ocean

Sayako Ueda, Yoko Iwamoto, Fumikazu Taketani, Mingxu Liu, and Hitoshi Matsui

Atmos. Chem. Phys., 23, 10117–10135, https://doi.org/10.5194/acp-23-10117-2023,https://doi.org/10.5194/acp-23-10117-2023, 2023

Short summary

Sayako Ueda et al.

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2023-389', Weijun Li, 09 Apr 2023
Comments
This manuscript by Ueda et al., investigated the morphological features, mixing states and water solubility of Fe-containing particles in aged fine aerosol particles over the Indian Ocean. The topic of this study is attractive and interesting, which is very useful for understanding the ageing of particles and the dissolution of Fe-containing particles during the transport of aerosols and the morphology variations of Fe-containing particles. Overall, the manuscript is logical, and the main issues are very well discussed in this paper. I would therefore recommend this manuscript for publication after the authors have addressed the following comments.

Major concerns:
The units of horizontal variation of mass concentrations of (a) nss-SO₄^2-, (b) NH₄⁺, and (c) Fe in PM_2.5 in Figure 2 are μg/kg and ng/kg, however, there are μg/m³ and ng/m³in Table 2, which is confused for me, please explain the differences between the two units and make them uniform.

Figure 2c (mass concentrations of Fe) has two more data points compared to figures 2a and 2b. Why?

Line 232: “For non-sea-salt components, the relations between the doubled nss-SO₄²⁻ molar concentration and the NH₄⁺ plus nss-K⁺ molar concentration were usually between 1:1 and 2:1 (Fig. S1b), suggesting that nss-SO₄²⁻ originated from ammonium sulfate, ammonium bisulfate, and ammonium potassium rather than from sulfuric acid.” Here, “ammonium potassium” should be “potassium sulfate” ?

Line 227-228 and line 232-233: “The values of nss-K⁺, which are regarded as originating mainly from biomass burning……; For non-sea-salt components, the relations between the doubled nss-SO₄²⁻ molar concentration and the NH₄⁺ plus nss-K⁺ molar concentration were usually between 1:1 and 2:1”. The author argued that nss-K⁺ was mainly from biomass burning, please provide more evidence to support this view.

In the section: “3.2 Individual particle features and co-existing states with Fe of sulfate and soot”, the author chooses samples #01 and #07 as example to illustrate the individual particle features, however, I fail to get the idea why the author selects these two samples. Is there any special in these two samples, the reasons should be given.

Compared with the filed observation results, the CAM5-ATRAS model underestimates Fe by nearly 1/3 (from Figure 9a), why? Are there other unknown sources of Fe or is there a large uncertainty in the Fe emission inventory used by your model?

Some other minor issues:
Line 132: Cl^−-, NO₃⁻, SO₄²⁻, Na⁺, NH⁺……., here, “Cl^−- andNH⁺” should be revised to “Cl⁻ andNH₄⁺”. Please check the similar issues in whole text.

The numbers and letters are so small that they can't be read clearly in Figure 4 and Figure 7, please adjust the font size.
Citation: https://doi.org/10.5194/egusphere-2023-389-RC1
- AC1: 'Reply on RC1', Sayako Ueda, 12 Jun 2023
  
  We appreciate the many constructive comments offered by Prof. Weijun Li, which have improved our manuscript considerably. We have developed a response in the attached document.
  
  Citation: https://doi.org/10.5194/egusphere-2023-389-AC1
RC2:
'Comment on egusphere-2023-389', Anonymous Referee #3, 05 May 2023

Comments to the muanuscript egusphere-2023-389
Ueda et al. Morphological features and water solubility of iron in aged fine aerosol particles over the Indian Ocean.
Reviewer's comments
The authors investigate aerosol particles' iron (Fe) properties over the Indian Ocean aboard a research vessel. The article presents important information on these particles' morphology, concentration, and degree of solubility. In general terms, the article is well-written. However, some minor observations need to be addressed. The article can be accepted after answering the following questions.
Abstract
line 15. the authors mention that they analyzed particles in the size range 0.3-0.8, using a cascade impactor. As written, it appears that they studied a continuous range of particle sizes. However, the methodology mentions that the sampler only has three nominal sizes (1.6, 0.8, and 0.3 μm). Please mention these three sizes in the abstract.

Methodology

The water dialysis process was important to study the water's mixing state and elucidate the Fe's solubility. Could you expand the description of this technique and mention the instrument used for it?

Indicate the bibliographic source from which equations 1 and 2 were obtained.

Please revise the wording in the first line of the first paragraph of section 2.1. It is not easy to understand the name of the cruise ship where the study was conducted.
Line 200: Check the spelling in this sentence.
It is recommended to use the same concentration units in tables and figures. Tables 2 and 3 report the concentrations in μm/m3 and ng/m3, respectively. While in Figure 2, the units are reported as μg/kg.
Results
It is suggested that labels (a), (b), (c), and (d) have to be added to each panel in Figure 8. The figure caption should also be improved to make it easier to read.
Figure 10 has many elements. It is suggested to separate them and present some results individually. In addition, the figure caption is very long and difficult to read.

Citation: https://doi.org/10.5194/egusphere-2023-389-RC2
- AC2: 'Reply on RC2', Sayako Ueda, 12 Jun 2023
  
  We appreciate the many constructive comments offered by anonymous reviewer #3, which have improved our manuscript considerably. We have developed a response in the attached document.
  
  Citation: https://doi.org/10.5194/egusphere-2023-389-AC2

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2023-389', Weijun Li, 09 Apr 2023
Comments
This manuscript by Ueda et al., investigated the morphological features, mixing states and water solubility of Fe-containing particles in aged fine aerosol particles over the Indian Ocean. The topic of this study is attractive and interesting, which is very useful for understanding the ageing of particles and the dissolution of Fe-containing particles during the transport of aerosols and the morphology variations of Fe-containing particles. Overall, the manuscript is logical, and the main issues are very well discussed in this paper. I would therefore recommend this manuscript for publication after the authors have addressed the following comments.

Major concerns:
The units of horizontal variation of mass concentrations of (a) nss-SO₄^2-, (b) NH₄⁺, and (c) Fe in PM_2.5 in Figure 2 are μg/kg and ng/kg, however, there are μg/m³ and ng/m³in Table 2, which is confused for me, please explain the differences between the two units and make them uniform.

Figure 2c (mass concentrations of Fe) has two more data points compared to figures 2a and 2b. Why?

Line 232: “For non-sea-salt components, the relations between the doubled nss-SO₄²⁻ molar concentration and the NH₄⁺ plus nss-K⁺ molar concentration were usually between 1:1 and 2:1 (Fig. S1b), suggesting that nss-SO₄²⁻ originated from ammonium sulfate, ammonium bisulfate, and ammonium potassium rather than from sulfuric acid.” Here, “ammonium potassium” should be “potassium sulfate” ?

Line 227-228 and line 232-233: “The values of nss-K⁺, which are regarded as originating mainly from biomass burning……; For non-sea-salt components, the relations between the doubled nss-SO₄²⁻ molar concentration and the NH₄⁺ plus nss-K⁺ molar concentration were usually between 1:1 and 2:1”. The author argued that nss-K⁺ was mainly from biomass burning, please provide more evidence to support this view.

In the section: “3.2 Individual particle features and co-existing states with Fe of sulfate and soot”, the author chooses samples #01 and #07 as example to illustrate the individual particle features, however, I fail to get the idea why the author selects these two samples. Is there any special in these two samples, the reasons should be given.

Compared with the filed observation results, the CAM5-ATRAS model underestimates Fe by nearly 1/3 (from Figure 9a), why? Are there other unknown sources of Fe or is there a large uncertainty in the Fe emission inventory used by your model?

Some other minor issues:
Line 132: Cl^−-, NO₃⁻, SO₄²⁻, Na⁺, NH⁺……., here, “Cl^−- andNH⁺” should be revised to “Cl⁻ andNH₄⁺”. Please check the similar issues in whole text.

The numbers and letters are so small that they can't be read clearly in Figure 4 and Figure 7, please adjust the font size.
Citation: https://doi.org/10.5194/egusphere-2023-389-RC1
- AC1: 'Reply on RC1', Sayako Ueda, 12 Jun 2023
  
  We appreciate the many constructive comments offered by Prof. Weijun Li, which have improved our manuscript considerably. We have developed a response in the attached document.
  
  Citation: https://doi.org/10.5194/egusphere-2023-389-AC1
RC2:
'Comment on egusphere-2023-389', Anonymous Referee #3, 05 May 2023

Comments to the muanuscript egusphere-2023-389
Ueda et al. Morphological features and water solubility of iron in aged fine aerosol particles over the Indian Ocean.
Reviewer's comments
The authors investigate aerosol particles' iron (Fe) properties over the Indian Ocean aboard a research vessel. The article presents important information on these particles' morphology, concentration, and degree of solubility. In general terms, the article is well-written. However, some minor observations need to be addressed. The article can be accepted after answering the following questions.
Abstract
line 15. the authors mention that they analyzed particles in the size range 0.3-0.8, using a cascade impactor. As written, it appears that they studied a continuous range of particle sizes. However, the methodology mentions that the sampler only has three nominal sizes (1.6, 0.8, and 0.3 μm). Please mention these three sizes in the abstract.

Methodology

The water dialysis process was important to study the water's mixing state and elucidate the Fe's solubility. Could you expand the description of this technique and mention the instrument used for it?

Indicate the bibliographic source from which equations 1 and 2 were obtained.

Please revise the wording in the first line of the first paragraph of section 2.1. It is not easy to understand the name of the cruise ship where the study was conducted.
Line 200: Check the spelling in this sentence.
It is recommended to use the same concentration units in tables and figures. Tables 2 and 3 report the concentrations in μm/m3 and ng/m3, respectively. While in Figure 2, the units are reported as μg/kg.
Results
It is suggested that labels (a), (b), (c), and (d) have to be added to each panel in Figure 8. The figure caption should also be improved to make it easier to read.
Figure 10 has many elements. It is suggested to separate them and present some results individually. In addition, the figure caption is very long and difficult to read.

Citation: https://doi.org/10.5194/egusphere-2023-389-RC2
- AC2: 'Reply on RC2', Sayako Ueda, 12 Jun 2023
  
  We appreciate the many constructive comments offered by anonymous reviewer #3, which have improved our manuscript considerably. We have developed a response in the attached document.
  
  Citation: https://doi.org/10.5194/egusphere-2023-389-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 (12 Jun 2023) Author's response Author's tracked changes Manuscript

ED: Publish subject to minor revisions (review by editor) (23 Jun 2023) by Luis A. Ladino

I thank the authors for addressing most of the comments listed by both reviewers; however, the manuscript requires additional work before it can be accepted for publication in ACP.

Major/minor comments:

1. The authors argue that “This manuscript was checked according to the journal guidelines by a native-English speaking professional with experience in the review of technical documents in this field”; however, I found many grammatical errors along the document. I invite the authors to significantly improve the English of the entire manuscript.
2. Along the document there are too many qualitative words such as “Presumably”, “it might be”, and “might have”, among others. I invite the authors to avoid such statements and to be more quantitative.
3. I invite the authors to reduce the large number of self citations.
4. L247-248: I think this is rather speculative and it is not supported by the present results.
5. Make units consistent between Fig 2 and Table 2 and 3.
6. Figure 9. Add log scale in panel (a).

Technical comments:

L24-25: “aluminosilicate Fe contained in matter such”. Please re-write it.
L26: Do the authors mean “Fe-containg particles”?
L37: Add a reference after “areas”
L40: Add a reference after “areas”
L41: What do the authors mean with “evaporation and condensation processes”
L58: Add a reference after “sources”
L59: Add a reference after “Fe”
L60: This was mentioned 2 lines above
L63: Add a reference after “simulations”
L65: Add a reference after “insufficient”
L73: Add a reference after “areas”
L113-114: Why is it mentioned “ 6–16 November 2018” twice. This is unclear.
L128: (a.s.l. 14 m).?
L132: “the home laboratory”?
L143: “Aerosol particles were collected for morphological particle analysis using TEM” What does it mean?
L144: “cascade impactors”. Please add model and manufacturer.
L146: “flow rate of 1.0 L min−1.” It this correct? This looks pretty low to me.
L224: Is “water” an aerosol species?
L243: “2018, when rain events occurred”. Where is this shown?
L243-244: “”The values of nss-K+, also tended to be north of the equator. What does it mean?
L314-315: “that they have hygroscopicity”. What does it mean?
L316-317: “are probably formed with secondary formation”. What does it mean?
L319: I think “under their deliquescence humidity” can be deleted.
L362: “the Fe-containing particles mixed with both Ca and Mg were only one”. What does it mean?
L 379: Replace “Sects” with “Sections”
L492: “Fe/Pd” should be in italics.

Hide

AR by Sayako Ueda on behalf of the Authors (15 Jul 2023) Author's response Author's tracked changes Manuscript

ED: Publish subject to minor revisions (review by editor) (26 Jul 2023) by Luis A. Ladino

AR by Sayako Ueda on behalf of the Authors (27 Jul 2023) Author's response Author's tracked changes Manuscript

ED: Publish as is (27 Jul 2023) by Luis A. Ladino

AR by Sayako Ueda on behalf of the Authors (01 Aug 2023) Author's response Manuscript

Journal article(s) based on this preprint

11 Sep 2023

Morphological features and water solubility of iron in aged fine aerosol particles over the Indian Ocean

Sayako Ueda, Yoko Iwamoto, Fumikazu Taketani, Mingxu Liu, and Hitoshi Matsui

Atmos. Chem. Phys., 23, 10117–10135, https://doi.org/10.5194/acp-23-10117-2023,https://doi.org/10.5194/acp-23-10117-2023, 2023

Short summary

Sayako Ueda et al.

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Sayako Ueda et al.

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Short summary

We investigated iron in atmospheric fine aerosol particles collected over the Indian Ocean during November 2018 shipborne observations. TEM analysis with water dialysis indicates that various types of iron, such as fly ash, iron oxide and mineral dust, coexist with ammonium sulfate, and that their solubility differs depending on the iron type. Using PM_2.5 bulk samples and global model simulations, we elucidated their origins, aging, and implications for present simulations of iron.


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