the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 04 Oct 2023
Role of sea spray aerosol at the air-sea interface in transporting aromatic acids to the atmosphere
Abstract. Aromatic acids are ubiquitous in seawater and can be transported to the atmosphere via sea spray aerosol (SSA). Despite their importance in affecting the global radiative balance, the contribution of marine aromatic acids and their transport mechanisms through SSA remain unclear. Herein, the distribution of particle size and number concentration of SSA produced in seawater containing nine different aromatic acids (i.e., benzoic acids, benzenedicarboxylic acids, hydroxybenzoic acids, vanillic acid, and syringic acid) was studied using a custom-made SSA simulation chamber; moreover, enrichment of aromatic acids in SSA and their emission flux to the atmosphere were analyzed. Transmission electron microscopy (TEM) images clearly revealed that aromatic acids can be transferred to the nascent SSA. Interestingly, the morphology associated with benzene dicarboxylic acids-coated particles showed that aromatic acids can promote the growth of other surfaces of sea salt, thus making the sea salt core spherical. Aromatic acids showed a significant enrichment behavior at the air-sea interface, which clearly indicated that SSA represent a source of aromatic acids in the atmosphere. Vanillic acid had the largest global emission flux through SSA (962 tons yr−1), even though its concentration in seawater was lower. The calculated results indicated that the global annual flux of aromatic acids was not only affected by the concentration in seawater, but also by their enrichment factor (EF). These data are critical for further quantifying the contribution of organic acids to the atmosphere via SSA, which may provide an estimate of the potential influence of the atmospheric feedbacks to the ocean carbon cycle.
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RC1: 'Comment on egusphere-2023-2011', Anonymous Referee #1, 10 Nov 2023
General comments
I find this manuscript well-written / well-referenced, scientifically interesting for the SSA community, and the experimental quality is good. I find it great that the authors try connect SSA experiments with functional group level chemistry.
I have some minor concerns, that should be easily to address. I would recommend publication with only minor revisions.
Specific comments
- Real seawater composition. In line 94 you write that you sample and transport seawater to the SSA laboratory. Is it possible to get more details? Conditions at sampling site (is it a productive area?), temperature, duration of storage, volume, was it filtered? Was it sampled on the same or different days? What time of year? You can add this information to the SI or just expand Table S1.
- Also I have had challenges when I sampled fresh real seawater, that the SSA properties (size and number) changed as a function of time in the SSA chamber (due to microbial activity, degassing) – I therefore sometimes prepared artificial seawater from just inorganic sea salts. Could the authors elaborate on how reproducible the experiments are? And would the authors expect the results being similar using artifical inorganic mixture?
- Experimental Setup. Would be helpful for the reader if Figure S1 was updated to include schematics of the entire setup, e.g. add where the DLPI+ was connected (before or after dryer?), single particle sampler (TEM). The air flow rate into SSA chamber (Line 109). Why does the range span from 3 all the way to 50 L min-1? Is it because you have different setups at different times during a single experiment? Could you elaborate more on this.
- TEM details. I am missing details about TEM instrument and conditions. When you do TEM, wouldn’t the organic coating of SSA just vaporize in the vacuum? Also, wouldn’t the SSA and aromatic acids be more internally mixed, when use a plunging jet / real bubble bursting?
Techical comments
Line 58: add mass, so it reads main mass component
Line 61: “... disturbing ecological systems... “, sound funny. Maybe change to “further impacting” or “further interaction with”
Line 163: The k look wierd, should be kSSA as in Sha et al, right? Also chemical symbols should be upright, not italic.
Line 202: Unit, Part s-1, would prefer just s-1 or particles s-1.
Line 207: what does increase in bubble bursting refer to? Is it foam stability or lifetime? Or smaller and more bubbles?
Line 260: change ball to sphere
Line 323: “lousy” is informal slang, change to “very poor” or just “poor” or “around and just below 1”.
Line 351: … plays a very important role… Tone down, add “might play”
Figure 1: Maybe same range on y-axis? Easier to compare across subplots. I am colorblind, do you need the colors? If you perfer using colors, then should be the same as in Figure 2.
Figure 2. I would change the colors. Yellow is difficult to see. Look at this website for inspiration: https://colorbrewer2.org/#type=diverging&scheme=BrBG&n=4
Figure 3. Seawater = Seawater only. And maybe add some errorbar estimation with respect to SSA production? Here color is okay, but that white shadow looks funny.
Figure 6: Maybe make different symbols and use one color? Feel free to ignore this comment.
Figure 7. The space between the bars are not the same. Also I would change colors (Feel free to igore this comment)
Citation: https://doi.org/10.5194/egusphere-2023-2011-RC1 - AC1: 'Reply on RC1', Yaru Song, 26 Dec 2023
- Real seawater composition. In line 94 you write that you sample and transport seawater to the SSA laboratory. Is it possible to get more details? Conditions at sampling site (is it a productive area?), temperature, duration of storage, volume, was it filtered? Was it sampled on the same or different days? What time of year? You can add this information to the SI or just expand Table S1.
-
CC1: 'Comment on egusphere-2023-2011', Bojiang Su, 15 Nov 2023
Dear Authors, editor, and reviewers,
This manuscript presents insights into the interactions between sea spray aerosols (SSAs) and aromatic acids through a laboratory study. This is an interesting and valuable research. I have some constructive comments on this manuscript.
Specific comments:
Abstract and Introduction:
Line 11, what is the importance of aromatic acids with SSAs in affecting the global radiative balance? In the following section of Introduction (Lines 29-40), the authors had ambiguous presentation in relationship between SSAs, aromatic acids, and global radiative balance.
Lines 41-54: The authors introduced the current studies in seawater source of aromatic acids in this paragraph, that is, the majority is from esters released and biodegraded by algae and the remain is from anthropogenic emissions. Could aromatic acids be derived from precipitation? What are the major types and their proportions and concentrations of aromatic acids in seawater? It should correspond to aromatic acids the authors used in the experiments (lines 90-98, 2 Experiment Section). More detailed description and possible summary are needed.
Line 80 Sintered glass filter and wave breaking method can also produce artificial SSAs with different properties of flux, chemical composition, size distribution, and so on. The authors should clarify the relationship between methods (sintered glass filter, plunging jet, and wave breaking) and possible efficiency of aromatic acid transport within SSAs. That is, whether the plunging jet method can effectively reflect the “Role of sea spray aerosol at the air-sea interface in transporting aromatic acids to the atmosphere”?
Experimental Section
Lines 90-97 Why do authors chose these types of aromatic acids? It should be clarified.
Lines 93-94 The collection procedure of seawater is not clear (site, chemical composition of seawater, contamination control, storge conditions, filtration or not?) Detailed QA/QC description is needed.
Line 98: What is the mass concentration of typical aromatic acids in true seawater, which determines whether the concentration of aromatic acid used in the experiment (1 mM) is reasonable.
Line 135 Can this flow rate of 1 mL min-1 for 1 h collect particles? If so, possible sampling artifacts should be considered. I think this flow rate is too small and cannot achieve/tune with DKL-2.
Results and discussion
Section 3.2.2 and Fig. 4
How quantitatively determine the thickness of organic coating of collected individual particles and what is the basis of the order? Can thickness of organic coating of selected individual particles represent the whole populations? Is there a statistic bias using only one typical TEM image?
Section 3.3
How many samples were used to calculate the enrichment factors of aromatic acids and cations (both in Figures 5 and 6)? It should be summarized as a new table. The authors performed size-resolved filter-based experiments, what is the level of enrichment factors of aromatic acids in different size?
The authors hypothesize that the binding effect of Ca2+ with aromatic acid is a reason for observed positive enrichment of aromatic acids. In fact, the positive calcium enrichment is also observed using artificial seawater without organic matters (Salter et al., 2016). Therefore, this hypothesis may need additional control experiments, for example, using pure NaCl solution with addition of aromatic acids, to excluded the effect of Ca2+.
Lines 313-326 I found a missing detail in authors evaluate the cation enrichments, that is, the detailed mass concentration ratio of cations to Na+, for example of Ca2+/Na+, in both seawater and aerosol samples is missing. I therefore suggest the authors supplement more details in mass concentration ratio of aromatic acids and cations in seawater and aerosol samples as a new table.
Minor comments:
Lines 57: Please clarify “a potential route”.
Lines 59-62: This sentence is hard to follow. What is that sea-salt included organic surfactants can thereby further disturbing ecological systems? The cited references also seem inappropriate.
Line 109 What is the air flow rate? It should be different in different experiment procedures.
Fig.3 It is hard to follow the differences in particle size, because these circles are almost identical.
Fig.4 It is hard to follow the colors of subplots A, B, and C. The color span between groups should be larger.
Reference
Salter, M. E., Hamacher-Barth, E., Leck, C., Werner, J., Johnson, C. M., Riipinen, I., Nilsson, E. D., and Zieger, P.: Calcium enrichment in sea spray aerosol particles, Geophys Res Lett, 43, 8277-8285, https://doi.org/10.1002/2016gl070275, 2016.
Citation: https://doi.org/10.5194/egusphere-2023-2011-CC1 - AC3: 'Reply on CC1', Yaru Song, 26 Dec 2023
-
RC2: 'Comment on egusphere-2023-2011', Matthew Salter, 21 Nov 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2011/egusphere-2023-2011-RC2-supplement.pdf
- AC2: 'Reply on RC2', Yaru Song, 26 Dec 2023
Status: closed
-
RC1: 'Comment on egusphere-2023-2011', Anonymous Referee #1, 10 Nov 2023
General comments
I find this manuscript well-written / well-referenced, scientifically interesting for the SSA community, and the experimental quality is good. I find it great that the authors try connect SSA experiments with functional group level chemistry.
I have some minor concerns, that should be easily to address. I would recommend publication with only minor revisions.
Specific comments
- Real seawater composition. In line 94 you write that you sample and transport seawater to the SSA laboratory. Is it possible to get more details? Conditions at sampling site (is it a productive area?), temperature, duration of storage, volume, was it filtered? Was it sampled on the same or different days? What time of year? You can add this information to the SI or just expand Table S1.
- Also I have had challenges when I sampled fresh real seawater, that the SSA properties (size and number) changed as a function of time in the SSA chamber (due to microbial activity, degassing) – I therefore sometimes prepared artificial seawater from just inorganic sea salts. Could the authors elaborate on how reproducible the experiments are? And would the authors expect the results being similar using artifical inorganic mixture?
- Experimental Setup. Would be helpful for the reader if Figure S1 was updated to include schematics of the entire setup, e.g. add where the DLPI+ was connected (before or after dryer?), single particle sampler (TEM). The air flow rate into SSA chamber (Line 109). Why does the range span from 3 all the way to 50 L min-1? Is it because you have different setups at different times during a single experiment? Could you elaborate more on this.
- TEM details. I am missing details about TEM instrument and conditions. When you do TEM, wouldn’t the organic coating of SSA just vaporize in the vacuum? Also, wouldn’t the SSA and aromatic acids be more internally mixed, when use a plunging jet / real bubble bursting?
Techical comments
Line 58: add mass, so it reads main mass component
Line 61: “... disturbing ecological systems... “, sound funny. Maybe change to “further impacting” or “further interaction with”
Line 163: The k look wierd, should be kSSA as in Sha et al, right? Also chemical symbols should be upright, not italic.
Line 202: Unit, Part s-1, would prefer just s-1 or particles s-1.
Line 207: what does increase in bubble bursting refer to? Is it foam stability or lifetime? Or smaller and more bubbles?
Line 260: change ball to sphere
Line 323: “lousy” is informal slang, change to “very poor” or just “poor” or “around and just below 1”.
Line 351: … plays a very important role… Tone down, add “might play”
Figure 1: Maybe same range on y-axis? Easier to compare across subplots. I am colorblind, do you need the colors? If you perfer using colors, then should be the same as in Figure 2.
Figure 2. I would change the colors. Yellow is difficult to see. Look at this website for inspiration: https://colorbrewer2.org/#type=diverging&scheme=BrBG&n=4
Figure 3. Seawater = Seawater only. And maybe add some errorbar estimation with respect to SSA production? Here color is okay, but that white shadow looks funny.
Figure 6: Maybe make different symbols and use one color? Feel free to ignore this comment.
Figure 7. The space between the bars are not the same. Also I would change colors (Feel free to igore this comment)
Citation: https://doi.org/10.5194/egusphere-2023-2011-RC1 - AC1: 'Reply on RC1', Yaru Song, 26 Dec 2023
- Real seawater composition. In line 94 you write that you sample and transport seawater to the SSA laboratory. Is it possible to get more details? Conditions at sampling site (is it a productive area?), temperature, duration of storage, volume, was it filtered? Was it sampled on the same or different days? What time of year? You can add this information to the SI or just expand Table S1.
-
CC1: 'Comment on egusphere-2023-2011', Bojiang Su, 15 Nov 2023
Dear Authors, editor, and reviewers,
This manuscript presents insights into the interactions between sea spray aerosols (SSAs) and aromatic acids through a laboratory study. This is an interesting and valuable research. I have some constructive comments on this manuscript.
Specific comments:
Abstract and Introduction:
Line 11, what is the importance of aromatic acids with SSAs in affecting the global radiative balance? In the following section of Introduction (Lines 29-40), the authors had ambiguous presentation in relationship between SSAs, aromatic acids, and global radiative balance.
Lines 41-54: The authors introduced the current studies in seawater source of aromatic acids in this paragraph, that is, the majority is from esters released and biodegraded by algae and the remain is from anthropogenic emissions. Could aromatic acids be derived from precipitation? What are the major types and their proportions and concentrations of aromatic acids in seawater? It should correspond to aromatic acids the authors used in the experiments (lines 90-98, 2 Experiment Section). More detailed description and possible summary are needed.
Line 80 Sintered glass filter and wave breaking method can also produce artificial SSAs with different properties of flux, chemical composition, size distribution, and so on. The authors should clarify the relationship between methods (sintered glass filter, plunging jet, and wave breaking) and possible efficiency of aromatic acid transport within SSAs. That is, whether the plunging jet method can effectively reflect the “Role of sea spray aerosol at the air-sea interface in transporting aromatic acids to the atmosphere”?
Experimental Section
Lines 90-97 Why do authors chose these types of aromatic acids? It should be clarified.
Lines 93-94 The collection procedure of seawater is not clear (site, chemical composition of seawater, contamination control, storge conditions, filtration or not?) Detailed QA/QC description is needed.
Line 98: What is the mass concentration of typical aromatic acids in true seawater, which determines whether the concentration of aromatic acid used in the experiment (1 mM) is reasonable.
Line 135 Can this flow rate of 1 mL min-1 for 1 h collect particles? If so, possible sampling artifacts should be considered. I think this flow rate is too small and cannot achieve/tune with DKL-2.
Results and discussion
Section 3.2.2 and Fig. 4
How quantitatively determine the thickness of organic coating of collected individual particles and what is the basis of the order? Can thickness of organic coating of selected individual particles represent the whole populations? Is there a statistic bias using only one typical TEM image?
Section 3.3
How many samples were used to calculate the enrichment factors of aromatic acids and cations (both in Figures 5 and 6)? It should be summarized as a new table. The authors performed size-resolved filter-based experiments, what is the level of enrichment factors of aromatic acids in different size?
The authors hypothesize that the binding effect of Ca2+ with aromatic acid is a reason for observed positive enrichment of aromatic acids. In fact, the positive calcium enrichment is also observed using artificial seawater without organic matters (Salter et al., 2016). Therefore, this hypothesis may need additional control experiments, for example, using pure NaCl solution with addition of aromatic acids, to excluded the effect of Ca2+.
Lines 313-326 I found a missing detail in authors evaluate the cation enrichments, that is, the detailed mass concentration ratio of cations to Na+, for example of Ca2+/Na+, in both seawater and aerosol samples is missing. I therefore suggest the authors supplement more details in mass concentration ratio of aromatic acids and cations in seawater and aerosol samples as a new table.
Minor comments:
Lines 57: Please clarify “a potential route”.
Lines 59-62: This sentence is hard to follow. What is that sea-salt included organic surfactants can thereby further disturbing ecological systems? The cited references also seem inappropriate.
Line 109 What is the air flow rate? It should be different in different experiment procedures.
Fig.3 It is hard to follow the differences in particle size, because these circles are almost identical.
Fig.4 It is hard to follow the colors of subplots A, B, and C. The color span between groups should be larger.
Reference
Salter, M. E., Hamacher-Barth, E., Leck, C., Werner, J., Johnson, C. M., Riipinen, I., Nilsson, E. D., and Zieger, P.: Calcium enrichment in sea spray aerosol particles, Geophys Res Lett, 43, 8277-8285, https://doi.org/10.1002/2016gl070275, 2016.
Citation: https://doi.org/10.5194/egusphere-2023-2011-CC1 - AC3: 'Reply on CC1', Yaru Song, 26 Dec 2023
-
RC2: 'Comment on egusphere-2023-2011', Matthew Salter, 21 Nov 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2011/egusphere-2023-2011-RC2-supplement.pdf
- AC2: 'Reply on RC2', Yaru Song, 26 Dec 2023
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