Optimized design of flux chambers for measurement of ammonia emission after field application of slurry with full-scale farm machinery

Pedersen, Johanna; Hafner, Sasha D.; Pacholski, Andreas; Karlsson, Valthor I.; Rong, Li; Labouriau, Rodrigo; Kamp, Jesper N.

doi:https://doi.org/10.5194/amt-2023-212

Preprints

https://doi.org/10.5194/amt-2023-212

Preprints

04 Jan 2024

| 04 Jan 2024

Status: a revised version of this preprint was accepted for the journal AMT and is expected to appear here in due course.

Optimized design of flux chambers for measurement of ammonia emission after field application of slurry with full-scale farm machinery

Johanna Pedersen, Sasha D. Hafner, Andreas Pacholski, Valthor I. Karlsson, Li Rong, Rodrigo Labouriau, and Jesper N. Kamp

Abstract. Field applied liquid animal manure (slurry) is a significant source of ammonia (NH₃) emission, which is harmful to the environment and human health. To evaluate mitigation options, reliable measurements of effects are needed. A new system of dynamic flux chambers (DFC) with high time resolution online measurements was developed. The system was investigated in silico with computational fluid dynamics and tested in three field trials, each trial assessing the variability after application with trailing hose at different scales: manual (handheld), 3-m experimental slurry boom, and 30-m farm-scale commercial slurry boom. For the experiments with machine application, parallel NH₃ emission measurements were made using an inverse dispersion modelling method (backward Lagrangian stochastic modelling, bLS). The lowest coefficient of variation of replicate DFC measurements was obtained with manual application, followed by the 3-m slurry boom, and lastly the 30-m slurry boom. Conditions in DFCs resulted in a consistently higher NH₃ flux than what was measured with the inverse dispersion technique but both methods showed a similar emission reduction by injection compared to trailing hose: 89 % by DFC and 97 % by bLS. The new measurement system facilitates NH₃ emission measurement with replication after both manual and farm-scale slurry application with relatively high precision, with a coefficient of variation of 5 % among replicates with manual slurry application and 20 % for farm-scale slurry application.

Received: 10 Oct 2023 – Discussion started: 04 Jan 2024

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Johanna Pedersen, Sasha D. Hafner, Andreas Pacholski, Valthor I. Karlsson, Li Rong, Rodrigo Labouriau, and Jesper N. Kamp

Status: closed

RC1:
'Comment on amt-2023-212', Anonymous Referee #1, 29 Jan 2024

The paper titled " Optimized design of flux chambers for measurement of ammonia emission after field application of slurry with full-scale farm machinery" aimed to investigate a new design of dynamic flux chambers (DFC) for NH3 emission measurements. The DFC was studied before with computational fluid dynamics and then tested in three field trials, in comparison to wind tunnels and backward Lagrangian stochastic method.
The intention of the paper is good and interesting and the nature of the problem is well introduced.
Materials and methods provide detailed instructions.
I suggest introducing a little discussion of the results, as well as possible implications of them. My specific comments are listed below:
Paragraph 3.1: please could you better clarify the geometry of the deflector plate and its function.
Lines 309-311: please add some references to this section in order to enhance the discussion part related to the CFD.
Lines 318-319: when you wrote about the final inlet design, could you describe it?
Figure 4 C: please explain the reason why there are so many differences among DFC replicates in the last trial.
Line 408: When you wrote “During both trials with parallel bLS measurements, the ambient wind speed was relatively low” is it possible that the air speed inside the chambers did not fit the wind speed of the external environment at the same height? Maybe it is higher, that is why you may have an overestimation of the NH3 emissions?

Citation: https://doi.org/10.5194/amt-2023-212-RC1
- AC1:
  'Reply on RC1', Johanna Pedersen, 06 May 2024
  Thank you for your valuable comments. Please find below our replies and actions on your specific comments.
  Comment: Paragraph 3.1: please could you better clarify the geometry of the deflector plate and its function.
  
  Reply: The geometry of the deflector plate is described in section ‘2.1.1 Chamber design’. This section also refers to Fig. 1 and S1 showing sketches of the DFC. The following sentence has been added to paragraph 2.1.1 to clarify the function of the deflector plate: ‘The design with a deflector plate was chosen in order to attempt to distribute the inflow air evenly above the emitting surface’.
  
  Comment: Lines 309-311: please add some references to this section in order to enhance the discussion part related to the CFD.
  
  Reply: A reference and some discussion has been added.
  
  Comment: Lines 318-319: When you wrote about the final inlet design, could you describe it?
  
  Reply: The inlet design is thoroughly described in section 2.1.3 (The new inlet design consisted of 100 mm PTFE tube (OD: 6.35 mm, ID: 4.75 mm) inserted into a 15 mL plastic centrifuge tube which was itself inserted into a 50 mL plastic centrifuge tube. All three (PTFE tube and both centrifuge tubes) had 3 rows of 5 small holes (Fig. S3)). A reference to this section has been added to section 3.2. discussing the inlet design.
  
  Comment: Figure 4C: Please explain the reason why there are so many differences among DFC replicates in the last trial.
  
  Reply: Please note that the y-scales in Fig. 4 differ, the following has been added to the figure text: ‘Please note that y-scale differs’. For ‘trial C, Injection’ the sd of the replicates is very low, but as the emission is also very low the cv is large (Table 4), implications of the variation among replicates are discussed in section 3.2.2. The variation is smaller than in trial B. We don’t think it is possible to draw further conclusions than the ones already discussed based on the small dataset.
  
  Comment: When you wrote ‘During both trials with parallel bLS measurements, the ambient wind speed was relatively low’ is it possible that the air speed inside the chambers did not fit the wind speed of the external environment at the same height? Maybe it is higher, that is why you may have an overestimation of the NH3 emissions?
  
  Action: We agree that the higher air speed inside the DFCs most likely caused the higher emissions measured with DFC compared to bLS, this is also stated in the same section: ‘Previous studies found that the differences between chamber and micrometeorological measurements can primarily be attributed to air-side mass transfer and rainfall (refs). It is likely that it is also the case in this study, as the measurements….’.
  
  Citation: https://doi.org/10.5194/amt-2023-212-AC1
RC2:
'Comment on amt-2023-212', A. Sanz-Cobena, 11 Apr 2024
Dear authors,
I have had the pleasure to revise your MS entitled “Optimized design of flux chambers for measurement of ammonia emission after field application of slurry with full-scale farm machinery”. The MS is nicely written and well structured. I have not observed any major constraint in your work thus I can recommend its publication in Atmospheric Measurement Techniques, which I do think is a good target journal for the publication of such type of research.
In my view, only few minor changes are needed prior publication. These minor comments are stated below:
Objectives of the work are presented at the end of the introduction but then a long statement on CFD (lines 50-60). Mybe better moving that text above thus clearly showing the objectives of the work for the readers.

In subsection 2.1.1. the sentence “Inspired by the laboratory chambers used by Dominique et al. (2013) and Georgios et al. (2013)” is just a repetition of the first sentence in section 2. Please, try to modify it to avoid being redundant.

Please, add the author/source of figure 1. Same for figure 2.

Line 160: “Anaerobically digested slurry”, cow slurry?

All tables. Please check and use the same type of letter than the full text.

Line 234. Please, check if there is a grey area in the reference.

Line 246. Please, check the size of the letter in the case of the reference.

Line 279. The year is missing for the reference used.

Reference list: be uniform with the style and size of letters for all references.

Yours sincerely,
Alberto Sanz-Cobeña
Citation: https://doi.org/10.5194/amt-2023-212-RC2
- AC2:
  'Reply on RC2', Johanna Pedersen, 06 May 2024
  Dear Alberto,
  
  Thank you for you valuable comments.
  
  Please find below our replies and actions on your specific comments.
  Comment 1: Objectives of the work are presented at the end of the introduction but then a long statement on CFD (lines 50-60). Maybe better moving that text above thus clearly showing the objectives of the work for the readers.
  
  Reply: The last section has been reorganized to make the objectives of the work clear, and a part of the CFD description has been moved down to section 2.1.2.
  
  Comment 2: In subsection 2.1.1 the sentence ‘Inspired by the laboratory chambers used by Dominique et al. (2013) and Georgios et al. (2013) is just a repetition of the first sentence in section 2. Please, try to modify it to avoid being redundant.
  
  Reply: To avoid unnecessary repetition the first part of the sentence in 2.1.1 has been deleted.
  
  Comment 3: Please, add the author/source of the figure 1. Same for figure 2.
  
  Reply: All figures are original creations of the authors. Source information can be provided if needed.
  
  Comment 4: Line 160: ‘Anaerobically digested slurry’, cow slurry?
  
  Reply: The digestate was produced from several sources of slurry and other organic materials. In section 2.2.2 a detailed description is provided: The digestate was produced at the biogas plant at Aarhus University, which operates two reactors in series at 51°C for 14 d and 47°C for 40 d. After the second reactor, the digestate was pumped to a concrete storage tank, where the digestate for the trials was collected. The input to the first reactor in the period where the digestate was produced for the trials was 82% mixed cattle and pig slurry, 9% deep litter, and 9% grass and grass silage (by fresh mass).
  
  Comment 5: All tables. Please check and use the same type of letter than the full text.
  
  Reply: All the tables have been checked and corrected to have same font and font size as full text.
  
  Comment 6: Line 234. Please, check if there is a grey area in the reference.
  
  Reply: The grey area has been removed.
  
  Comment 7: Line 246. Please, check the size of the letters in the case of the reference.
  
  Reply: The font size of the reference has been corrected.
  
  Comment 8: Line 279. The year is missing for the reference used.
  
  Reply: The year has been added.
  
  Comment 9: Reference list: be uniform with the style and size of letters for all references.
  
  Reply: The reference list has been thoroughly checked and the errors have been corrected.
  
  Citation: https://doi.org/10.5194/amt-2023-212-AC2
EC1: 'Comment on amt-2023-212', Daniela Famulari, 07 May 2024

The manuscript “Optimized design of flux chambers for measurement of ammonia emission after field application of slurry with full-scale farm machinery” reports over a study on a novel setup for enclosure measurements of gaseous NH3 emissions from slurry. I would suggest a change in the title “Evaluation of an optimized design of flux chambers for…”. In the sense that the described apparatus has been evaluated against models and in a field trial for different conditions: it is just a suggestion, up to the authors to decide. The study can be relevant to the NH3 research community, the replies to reviewers are satisfactory by me, and I agree with the reviewers that it should be published in AMT, as a step forward in the direction of enclosure methods, and not as “ultimate solution”. Indeed, the authors mention it in the conclusions. I recommend the authors to go ahead with the submission of the revised manuscript that includes all suggestions by reviewers.
A few remarks below, in addition to what the two reviewers have already written:
L15: “To evaluate mitigation options, reliable measurements of effects are needed”. I am not sure about this sentence: effects of NH3 on the environment? Effects of different practices on NH3 emissions?
Fig.1a resolution results inadequate, make sure in the final version you have high resolution figures.
L90: AER acronym is defined only later in text, correct that.
L212 what is a stream? An air-line?
L214-217 and from here on: AER measured in min-1? I don't understand this.
L309-311: This is something also the reviewers pointed out (in a different light): I understand the intention to create well mixed conditions within the enclosure; however, that affects the rate at which NH3 will volatilise from the surface, won’t it? Perhaps to justify the regimes of “wind” within the chamber, it would be useful to mention here what are the real wind conditions on the field, to justify the regime chosen for operation? Just a suggestion.

Citation: https://doi.org/10.5194/amt-2023-212-EC1

Status: closed

RC1:
'Comment on amt-2023-212', Anonymous Referee #1, 29 Jan 2024

The paper titled " Optimized design of flux chambers for measurement of ammonia emission after field application of slurry with full-scale farm machinery" aimed to investigate a new design of dynamic flux chambers (DFC) for NH3 emission measurements. The DFC was studied before with computational fluid dynamics and then tested in three field trials, in comparison to wind tunnels and backward Lagrangian stochastic method.
The intention of the paper is good and interesting and the nature of the problem is well introduced.
Materials and methods provide detailed instructions.
I suggest introducing a little discussion of the results, as well as possible implications of them. My specific comments are listed below:
Paragraph 3.1: please could you better clarify the geometry of the deflector plate and its function.
Lines 309-311: please add some references to this section in order to enhance the discussion part related to the CFD.
Lines 318-319: when you wrote about the final inlet design, could you describe it?
Figure 4 C: please explain the reason why there are so many differences among DFC replicates in the last trial.
Line 408: When you wrote “During both trials with parallel bLS measurements, the ambient wind speed was relatively low” is it possible that the air speed inside the chambers did not fit the wind speed of the external environment at the same height? Maybe it is higher, that is why you may have an overestimation of the NH3 emissions?

Citation: https://doi.org/10.5194/amt-2023-212-RC1
- AC1:
  'Reply on RC1', Johanna Pedersen, 06 May 2024
  Thank you for your valuable comments. Please find below our replies and actions on your specific comments.
  Comment: Paragraph 3.1: please could you better clarify the geometry of the deflector plate and its function.
  
  Reply: The geometry of the deflector plate is described in section ‘2.1.1 Chamber design’. This section also refers to Fig. 1 and S1 showing sketches of the DFC. The following sentence has been added to paragraph 2.1.1 to clarify the function of the deflector plate: ‘The design with a deflector plate was chosen in order to attempt to distribute the inflow air evenly above the emitting surface’.
  
  Comment: Lines 309-311: please add some references to this section in order to enhance the discussion part related to the CFD.
  
  Reply: A reference and some discussion has been added.
  
  Comment: Lines 318-319: When you wrote about the final inlet design, could you describe it?
  
  Reply: The inlet design is thoroughly described in section 2.1.3 (The new inlet design consisted of 100 mm PTFE tube (OD: 6.35 mm, ID: 4.75 mm) inserted into a 15 mL plastic centrifuge tube which was itself inserted into a 50 mL plastic centrifuge tube. All three (PTFE tube and both centrifuge tubes) had 3 rows of 5 small holes (Fig. S3)). A reference to this section has been added to section 3.2. discussing the inlet design.
  
  Comment: Figure 4C: Please explain the reason why there are so many differences among DFC replicates in the last trial.
  
  Reply: Please note that the y-scales in Fig. 4 differ, the following has been added to the figure text: ‘Please note that y-scale differs’. For ‘trial C, Injection’ the sd of the replicates is very low, but as the emission is also very low the cv is large (Table 4), implications of the variation among replicates are discussed in section 3.2.2. The variation is smaller than in trial B. We don’t think it is possible to draw further conclusions than the ones already discussed based on the small dataset.
  
  Comment: When you wrote ‘During both trials with parallel bLS measurements, the ambient wind speed was relatively low’ is it possible that the air speed inside the chambers did not fit the wind speed of the external environment at the same height? Maybe it is higher, that is why you may have an overestimation of the NH3 emissions?
  
  Action: We agree that the higher air speed inside the DFCs most likely caused the higher emissions measured with DFC compared to bLS, this is also stated in the same section: ‘Previous studies found that the differences between chamber and micrometeorological measurements can primarily be attributed to air-side mass transfer and rainfall (refs). It is likely that it is also the case in this study, as the measurements….’.
  
  Citation: https://doi.org/10.5194/amt-2023-212-AC1
RC2:
'Comment on amt-2023-212', A. Sanz-Cobena, 11 Apr 2024
Dear authors,
I have had the pleasure to revise your MS entitled “Optimized design of flux chambers for measurement of ammonia emission after field application of slurry with full-scale farm machinery”. The MS is nicely written and well structured. I have not observed any major constraint in your work thus I can recommend its publication in Atmospheric Measurement Techniques, which I do think is a good target journal for the publication of such type of research.
In my view, only few minor changes are needed prior publication. These minor comments are stated below:
Objectives of the work are presented at the end of the introduction but then a long statement on CFD (lines 50-60). Mybe better moving that text above thus clearly showing the objectives of the work for the readers.

In subsection 2.1.1. the sentence “Inspired by the laboratory chambers used by Dominique et al. (2013) and Georgios et al. (2013)” is just a repetition of the first sentence in section 2. Please, try to modify it to avoid being redundant.

Please, add the author/source of figure 1. Same for figure 2.

Line 160: “Anaerobically digested slurry”, cow slurry?

All tables. Please check and use the same type of letter than the full text.

Line 234. Please, check if there is a grey area in the reference.

Line 246. Please, check the size of the letter in the case of the reference.

Line 279. The year is missing for the reference used.

Reference list: be uniform with the style and size of letters for all references.

Yours sincerely,
Alberto Sanz-Cobeña
Citation: https://doi.org/10.5194/amt-2023-212-RC2
- AC2:
  'Reply on RC2', Johanna Pedersen, 06 May 2024
  Dear Alberto,
  
  Thank you for you valuable comments.
  
  Please find below our replies and actions on your specific comments.
  Comment 1: Objectives of the work are presented at the end of the introduction but then a long statement on CFD (lines 50-60). Maybe better moving that text above thus clearly showing the objectives of the work for the readers.
  
  Reply: The last section has been reorganized to make the objectives of the work clear, and a part of the CFD description has been moved down to section 2.1.2.
  
  Comment 2: In subsection 2.1.1 the sentence ‘Inspired by the laboratory chambers used by Dominique et al. (2013) and Georgios et al. (2013) is just a repetition of the first sentence in section 2. Please, try to modify it to avoid being redundant.
  
  Reply: To avoid unnecessary repetition the first part of the sentence in 2.1.1 has been deleted.
  
  Comment 3: Please, add the author/source of the figure 1. Same for figure 2.
  
  Reply: All figures are original creations of the authors. Source information can be provided if needed.
  
  Comment 4: Line 160: ‘Anaerobically digested slurry’, cow slurry?
  
  Reply: The digestate was produced from several sources of slurry and other organic materials. In section 2.2.2 a detailed description is provided: The digestate was produced at the biogas plant at Aarhus University, which operates two reactors in series at 51°C for 14 d and 47°C for 40 d. After the second reactor, the digestate was pumped to a concrete storage tank, where the digestate for the trials was collected. The input to the first reactor in the period where the digestate was produced for the trials was 82% mixed cattle and pig slurry, 9% deep litter, and 9% grass and grass silage (by fresh mass).
  
  Comment 5: All tables. Please check and use the same type of letter than the full text.
  
  Reply: All the tables have been checked and corrected to have same font and font size as full text.
  
  Comment 6: Line 234. Please, check if there is a grey area in the reference.
  
  Reply: The grey area has been removed.
  
  Comment 7: Line 246. Please, check the size of the letters in the case of the reference.
  
  Reply: The font size of the reference has been corrected.
  
  Comment 8: Line 279. The year is missing for the reference used.
  
  Reply: The year has been added.
  
  Comment 9: Reference list: be uniform with the style and size of letters for all references.
  
  Reply: The reference list has been thoroughly checked and the errors have been corrected.
  
  Citation: https://doi.org/10.5194/amt-2023-212-AC2
EC1: 'Comment on amt-2023-212', Daniela Famulari, 07 May 2024

The manuscript “Optimized design of flux chambers for measurement of ammonia emission after field application of slurry with full-scale farm machinery” reports over a study on a novel setup for enclosure measurements of gaseous NH3 emissions from slurry. I would suggest a change in the title “Evaluation of an optimized design of flux chambers for…”. In the sense that the described apparatus has been evaluated against models and in a field trial for different conditions: it is just a suggestion, up to the authors to decide. The study can be relevant to the NH3 research community, the replies to reviewers are satisfactory by me, and I agree with the reviewers that it should be published in AMT, as a step forward in the direction of enclosure methods, and not as “ultimate solution”. Indeed, the authors mention it in the conclusions. I recommend the authors to go ahead with the submission of the revised manuscript that includes all suggestions by reviewers.
A few remarks below, in addition to what the two reviewers have already written:
L15: “To evaluate mitigation options, reliable measurements of effects are needed”. I am not sure about this sentence: effects of NH3 on the environment? Effects of different practices on NH3 emissions?
Fig.1a resolution results inadequate, make sure in the final version you have high resolution figures.
L90: AER acronym is defined only later in text, correct that.
L212 what is a stream? An air-line?
L214-217 and from here on: AER measured in min-1? I don't understand this.
L309-311: This is something also the reviewers pointed out (in a different light): I understand the intention to create well mixed conditions within the enclosure; however, that affects the rate at which NH3 will volatilise from the surface, won’t it? Perhaps to justify the regimes of “wind” within the chamber, it would be useful to mention here what are the real wind conditions on the field, to justify the regime chosen for operation? Just a suggestion.

Citation: https://doi.org/10.5194/amt-2023-212-EC1

Johanna Pedersen, Sasha D. Hafner, Andreas Pacholski, Valthor I. Karlsson, Li Rong, Rodrigo Labouriau, and Jesper N. Kamp

Supplement

https://doi.org/10.5194/amt-2023-212-supplement

Johanna Pedersen, Sasha D. Hafner, Andreas Pacholski, Valthor I. Karlsson, Li Rong, Rodrigo Labouriau, and Jesper N. Kamp

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Short summary

Field applied animal slurry is a significant source of NH₃ emission. A new system of dynamic flux chambers for NH₃ measurements was developed and validated through three field trials, used to assess the variability after application with trailing hose at different scales: manual (handheld), 3-m slurry boom, and 30-m slurry boom. The measurement system facilitates NH₃ emission measurement with replication after both manual and farm-scale slurry application with relatively high precision.


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