the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 20 Jan 2025
Development and use of a lightweight sampling system for height-selective drone-based measurements of organic aerosol particles
Abstract. Organic aerosols (OA) are introduced into the atmosphere from a variety of natural or anthropogenic sources. Especially in the sub micrometer range, the organic fraction contributes to a large proportion of the particle mass and thus has an impact on climate and air quality. To gain insights into sources and sinks and the significance of dispersion, mixing and ageing processes for OA, vertical profiling of the concentration of organic aerosols is particularly helpful. Therefore, the aim of this study is to present an aerosol particle sampler that is suitable to be used onboard uncrewed aerial vehicles (UAVs). The sampler consists of a three-dimensionally printed filter holder connected to a lightweight high-performance pump that can generate a flow rate of up to 19 L min-1 for up to 30 minutes. The sampler was characterized and applied on a proof-of-concept study during the BISTUM23 campaign in August 2023 in Southern Germany. Vertical profiles were measured with three samplers mounted on ground and drones and collected aerosol particles in an altitude of 1.5 m, 120 m and 500 m above ground level simultaneously. The filters were analyzed with UHPLC-HRMS, and a targeted approach was used to determine vertical profiles and diurnal trends of biogenic, anthropogenic and biomass burning marker compounds. A non-targeted analysis revealed a high number of CHO-containing compounds, which were oxidized to a greater extent during the course of the day and at increasing altitudes. The system presented here provides a comparatively simple and cost-effective way to sample OA at different altitudes and at different locations and thus obtain vertical concentration profiles of the organic aerosol composition.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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Supplement
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1620 KB) - Metadata XML
-
Supplement
(1153 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2024-4015', Anonymous Referee #1, 07 Feb 2025
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AC1: 'Reply on RC1', Thorsten Hoffmann, 20 May 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4015/egusphere-2024-4015-AC1-supplement.pdf
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AC1: 'Reply on RC1', Thorsten Hoffmann, 20 May 2025
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RC2: 'Comment on egusphere-2024-4015', Anonymous Referee #2, 05 Mar 2025
In the manuscript, authors are presenting interesting results for atmospheric organic aerosols sampled with lightweight filtration system in the aerial drone. The manuscript is mostly well done and written, although some minor inaccuracies exist and need to be fixed.
- Page 3, line 65: What was the material used for printing the filter holder?
- Page 3, line 83: Generally the best sampling point is under the body of the drone/sampling unit (less affected by the flow caused by propellers)?
- Page 4, lines 96-99: Total volume of extraction solutions will be 3mL+1.5mL+1.5mL. How this (6 mL together) can be transferred to 1.5mL vial? Rewrite to clarify what was done and how. Also give the volume to what the supernatant was concentrated under N2
- Page 4, lines 105-110: Generally, both A and B eluent components should contain 0.04% formic acid. Then its amount (and eluent pH) would stay constant. Now the pH will change during the concentration gradient. Also you should report what was the pH. For acidic compounds with negative ESI, basic conditions are normally used for efficient ionization and good sensitivity. Now the conditions used are more suitable for positive ESI. You could have tried to modify the eluent and pH used for example adding ammonium acetate or ammonium fluoride instead of formic acid. If the chromatography is not good with these, then this modification could be done post column with ESI nebulizing liquid.
- Page 4, lines 116-117: The voltage regulator would be good to include in the future (and maybe mention this in the conclusions).
- Figure 7, figure legend: 10:35 is as far from the noon as is 13:35. You could talk about late morning (10:35am), early afternoon (13.35pm) and late afternoon (4:30pm)? Also for some cases you have 24h system (13:35 pm) and some 12 h system (4:30 pm), so be consistent. Fix these throughout the whole manuscript (at least in Figure 6 there is 13:35 pm).
Citation: https://doi.org/10.5194/egusphere-2024-4015-RC2 -
AC2: 'Reply on RC2', Thorsten Hoffmann, 20 May 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4015/egusphere-2024-4015-AC2-supplement.pdf
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RC3: 'Comment on egusphere-2024-4015', Anonymous Referee #3, 04 Apr 2025
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AC3: 'Reply on RC3', Thorsten Hoffmann, 20 May 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4015/egusphere-2024-4015-AC3-supplement.pdf
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AC3: 'Reply on RC3', Thorsten Hoffmann, 20 May 2025
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2024-4015', Anonymous Referee #1, 07 Feb 2025
The authors describe a lightweight UAV system for measuring organic aerosol particles and present first vertical measurements from a rural area in southern Germany. The paper is well written and fits within the scope of AMT. However, there are some problems that need to be corrected before the manuscript can be published.
Major comments
Introduction
Why does the paper only mention vertical profile measurements? UAVs are particularly suited for horizontal measurements, which supply the benefit of scanning areas and understanding emission sources (see literature).
Experimental procedures
Have you studied the turbulence of the rotor? Most groups working on aerosol sampling with UAVs use smog experiments to make turbulence visible. The position of your setup is given in the appendix. However, the pictures don't show the dimensions. Please add these dimensions to the pictures or provide a sketch with the dimensions. This is especially important for the distance between the instrument and the rotors. Since the results are very impressive and the effect of turbulence can obviously be neglected, the question is why. After all, the body of the UAV acts as a kind of shield and allows a shielding flow around the UAV? A colored smog test would show this.
Figure 1 shows a schematic of the filter holder. Again, the dimensions are missing. How long is the filter holder? What is the length and diameter of the pump? What is the diameter of the pump inlet? What is the distance from the filter to the pump inlet?
Have you determined the deposition characteristics of your filter holder? What are the diameters of the particles (size range) being filtered? Have you determined the total number of particles you are filtering per volume? What are the particle concentrations in number and mass?
Other parameters that are missing are the down wash distribution, the rotor speed, and the weight of the sampling unit.
Can you open and close the inlet to your filter assembly or can you turn the pump on and off during the flight to ensure that you are sampling only from the appropriate altitude?
Electronic circuits and the schematic structure of the measuring unit are also missing. If software was used for the control system, this must also be specified in the appendix.
Results and Conclusions
The manuscript presents an impressive proof of concept. The results are robust and in line with expectations for the measurement situation. However, more information on the setup is needed to evaluate the errors.
Minor comment
“UAV” is the common term. You could use "UAV" instead of "drone".
Citation: https://doi.org/10.5194/egusphere-2024-4015-RC1 -
AC1: 'Reply on RC1', Thorsten Hoffmann, 20 May 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4015/egusphere-2024-4015-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Thorsten Hoffmann, 20 May 2025
-
RC2: 'Comment on egusphere-2024-4015', Anonymous Referee #2, 05 Mar 2025
In the manuscript, authors are presenting interesting results for atmospheric organic aerosols sampled with lightweight filtration system in the aerial drone. The manuscript is mostly well done and written, although some minor inaccuracies exist and need to be fixed.
- Page 3, line 65: What was the material used for printing the filter holder?
- Page 3, line 83: Generally the best sampling point is under the body of the drone/sampling unit (less affected by the flow caused by propellers)?
- Page 4, lines 96-99: Total volume of extraction solutions will be 3mL+1.5mL+1.5mL. How this (6 mL together) can be transferred to 1.5mL vial? Rewrite to clarify what was done and how. Also give the volume to what the supernatant was concentrated under N2
- Page 4, lines 105-110: Generally, both A and B eluent components should contain 0.04% formic acid. Then its amount (and eluent pH) would stay constant. Now the pH will change during the concentration gradient. Also you should report what was the pH. For acidic compounds with negative ESI, basic conditions are normally used for efficient ionization and good sensitivity. Now the conditions used are more suitable for positive ESI. You could have tried to modify the eluent and pH used for example adding ammonium acetate or ammonium fluoride instead of formic acid. If the chromatography is not good with these, then this modification could be done post column with ESI nebulizing liquid.
- Page 4, lines 116-117: The voltage regulator would be good to include in the future (and maybe mention this in the conclusions).
- Figure 7, figure legend: 10:35 is as far from the noon as is 13:35. You could talk about late morning (10:35am), early afternoon (13.35pm) and late afternoon (4:30pm)? Also for some cases you have 24h system (13:35 pm) and some 12 h system (4:30 pm), so be consistent. Fix these throughout the whole manuscript (at least in Figure 6 there is 13:35 pm).
Citation: https://doi.org/10.5194/egusphere-2024-4015-RC2 -
AC2: 'Reply on RC2', Thorsten Hoffmann, 20 May 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4015/egusphere-2024-4015-AC2-supplement.pdf
-
RC3: 'Comment on egusphere-2024-4015', Anonymous Referee #3, 04 Apr 2025
-
AC3: 'Reply on RC3', Thorsten Hoffmann, 20 May 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4015/egusphere-2024-4015-AC3-supplement.pdf
-
AC3: 'Reply on RC3', Thorsten Hoffmann, 20 May 2025
Peer review completion
Journal article(s) based on this preprint
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Christine Borchers
Lasse Moormann
Bastien Geil
Niklas Karbach
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1620 KB) - Metadata XML
-
Supplement
(1153 KB) - BibTeX
- EndNote
- Final revised paper
The authors describe a lightweight UAV system for measuring organic aerosol particles and present first vertical measurements from a rural area in southern Germany. The paper is well written and fits within the scope of AMT. However, there are some problems that need to be corrected before the manuscript can be published.
Major comments
Introduction
Why does the paper only mention vertical profile measurements? UAVs are particularly suited for horizontal measurements, which supply the benefit of scanning areas and understanding emission sources (see literature).
Experimental procedures
Have you studied the turbulence of the rotor? Most groups working on aerosol sampling with UAVs use smog experiments to make turbulence visible. The position of your setup is given in the appendix. However, the pictures don't show the dimensions. Please add these dimensions to the pictures or provide a sketch with the dimensions. This is especially important for the distance between the instrument and the rotors. Since the results are very impressive and the effect of turbulence can obviously be neglected, the question is why. After all, the body of the UAV acts as a kind of shield and allows a shielding flow around the UAV? A colored smog test would show this.
Figure 1 shows a schematic of the filter holder. Again, the dimensions are missing. How long is the filter holder? What is the length and diameter of the pump? What is the diameter of the pump inlet? What is the distance from the filter to the pump inlet?
Have you determined the deposition characteristics of your filter holder? What are the diameters of the particles (size range) being filtered? Have you determined the total number of particles you are filtering per volume? What are the particle concentrations in number and mass?
Other parameters that are missing are the down wash distribution, the rotor speed, and the weight of the sampling unit.
Can you open and close the inlet to your filter assembly or can you turn the pump on and off during the flight to ensure that you are sampling only from the appropriate altitude?
Electronic circuits and the schematic structure of the measuring unit are also missing. If software was used for the control system, this must also be specified in the appendix.
Results and Conclusions
The manuscript presents an impressive proof of concept. The results are robust and in line with expectations for the measurement situation. However, more information on the setup is needed to evaluate the errors.
Minor comment
“UAV” is the common term. You could use "UAV" instead of "drone".