the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 15 Jan 2025
Calibrating adsorptive and reactive losses of monoterpenes and sesquiterpenes in dynamic chambers using deuterated surrogates
Abstract. Accurately measuring the emissions of monoterpenes (MTs) and sesquiterpenes (SQTs) using dynamic chambers requires careful consideration of their adsorptive and reactive losses, which are often overlooked and difficult to assess in situ. This study evaluated the effectiveness of deuterated surrogates, α-pinene-d3 and β-caryophyllene-d2, in tracing these losses in a dynamic chamber system. Using standard gas mixtures of 10 MTs and 10 SQTs, we characterized adsorptive losses across varying concentrations, temperatures, and humidity levels, as well as reactive losses with ozone. Results indicated that adsorptive losses were significantly influenced by concentration and temperature, with species-specific variations particularly under low concentrations and low temperatures, while relative humidity had negligible impact. Reactive losses with ozone exhibited substantial species-specific variability. Key MTs (α-pinene, β-pinene, 3-carene, limonene, and 1,8-cineole) and SQTs (β-caryophyllene and α-humulene) demonstrated consistent adsorptive and reactive behavior with their respective deuterated surrogates α-pinene-d3 and β-caryophyllene-d2, suggesting that these surrogates are effective for correcting losses in in-situ emission measurements using dynamic chambers. However, due to varied adsorptive and reactive losses, additional deuterated MTs and SQTs are recommended, particularly selected according to their O3 reactivities, to cover a broader range of MTs and SQTs for loss correction. A strong correlation between adsorptive capacity and ozone reactivity was observed, underscoring the need to carefully address losses of highly reactive MTs and SQTs during emission measurements. This study also emphasizes that ozone-free circulating air should be used for accurately measuring emissions of highly reactive SQTs, such as β-caryophyllene and α-humulene, especially when loss correction methods are unavailable.
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RC1: 'Comment on amt-2024-170', Tao Li, 06 Feb 2025
This study utilized 10 monoterpenes and 10 sesquiterpenes, which are commonly emitted from vegetation, to evaluate the reactive and adsorptive losses of volatile organic compounds inside the enclosure using dynamic headspace sampling approaches. In addition, two deuterium-labeled compounds were used to assess whether they could serve as internal standards for evaluating reactive and adsorptive losses of terpenoids during in situ field measurements. Overall, this study is well-written and provide valuable insights into for designing field-based volatile measurement systems to miminize adsorptive and reactive losses. I have a few minor comments that should to be addressed in the revision.
- It is unclear how the deuterium-labeled compounds were quantified using GC-MS. A detailed description of the quantification method should be provided either in the M&M section or in the supplementary document.
- It is unclear in which lab experiments the ozone scrubbers were used. Since all experiments appears to have used dry air and if the compressed dry air was free of ozone, it is hard to understand why ozone scrubber is needed. Nonetheless, the author needs to clarify this point to avoid misunderstanding.
- While it sounds reasonable to use deuterium-labeled compounds, which are not emitted by the target research subjects, as internal standard in field measurement campaigns to account for the potential adsorptive and reactive losses of plant-derived volatiles, correction factors derived from these deuterium-labeled compounds still should to be explained with caution. This is because adsorptive losses of these deuterium-labeled compounds cannot only occur on the inner surface of the enclosure, but also on the plant surface (especially leaf surface for broad-leaf species) either by passive deposition or active uptake by plants. When the relative contribution of these two process is not known, the applicability of deuterium-labeled compounds for assessing adsorptive losses may be limited. Anyway, I suggest that the authors should address these considerations in the discussion.
- It is unclear how many replicates were used for each experiment, and what the error bars in the figure or the text refer to (standard deviation or standard error?).
Some grammatical errors should be corrected, e.g.,
Line 65, change “existed” to “exists”
Line 72 change “by using surrogates like aromatic compounds with quite different reactivity with O3.” to “by using surrogates like aromatic compounds that have quite different reactivity with O3.”
Citation: https://doi.org/10.5194/amt-2024-170-RC1 -
AC1: 'Reply on RC1', Zeng Jianqiang, 20 Feb 2025
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2024-170/amt-2024-170-AC1-supplement.pdf
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RC2: 'Comment on amt-2024-170', Anonymous Referee #2, 12 Feb 2025
This study evaluates deuterated surrogates (α-pinene-d3 and β-caryophyllene-d2) for tracing adsorptive and reactive losses of monoterpenes (MTs) and sesquiterpenes (SQTs) in dynamic chambers. Using standard gas mixtures, it examines the effects of concentration, temperature, humidity, and O3. Adsorptive losses varied with concentration and temperature, while O3-induced losses were species-specific. The surrogates effectively corrected losses, but additional deuterated compounds are recommended for broader coverage. A strong correlation between adsorption and O3 reactivity underscores the need for careful loss correction, particularly for highly reactive SQTs, which should be measured with O3-free air when correction is unavailable. Overall, the manuscript is well written, and the results are valuable to the literature. I have some minor comments:
- Lines 82-83: Please briefly mention the size and dimensions of the chamber, as they affect VOC losses via surface adsorption.
- Section 3.1: Is there an adsorption model that can be used to quantify VOC loss? The authors may refer to He et al. (AMT, 2024) for relevant methods. (Reference: He, L., Liu, W., Li, Y., Wang, J., Kuwata, M., and Liu, Y.: Wall loss of semi-volatile organic compounds in a Teflon bag chamber for the temperature range of 262–298 K: mechanistic insight on temperature dependence, Atmos. Meas. Tech., 17, 755–764, https://doi.org/10.5194/amt-17-755-2024, 2024).
- Lines 136-137: Please add references to this sentence.
- Lines 142-148: Why do reactive VOCs exhibit greater adsorption loss? Any explanation?
- Line 181: Why not use α-pinene or β-caryophyllene directly instead of their isotopes for calibrating losses?
- Lines 191-193: Any suggestions for green leaf volatiles such as aldehydes and alcohols? How does humidity impact their losses? Please discuss.
- Line 197: Were O3 scrubbers or denuders applied before cartridge sampling?
- Lines 245-249: Sesquiterpene emissions from plants may be more sensitive to O3 stress as reported by the literature. Using O3-free air may not reflect real-world conditions. Why not apply a correction factor for sesquiterpene loss due to O3 instead?
- Table 1: It would be useful to include literature-reported reaction rates for compounds in both groups 1 and 2, which helps readers understand the extent of reaction rate differences.
- Lines 273-274: Again, would chamber-specific correction factors for different VOCs be more effective?
Citation: https://doi.org/10.5194/amt-2024-170-RC2 -
AC2: 'Reply on RC2', Zeng Jianqiang, 20 Feb 2025
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2024-170/amt-2024-170-AC2-supplement.pdf
Status: closed
-
RC1: 'Comment on amt-2024-170', Tao Li, 06 Feb 2025
This study utilized 10 monoterpenes and 10 sesquiterpenes, which are commonly emitted from vegetation, to evaluate the reactive and adsorptive losses of volatile organic compounds inside the enclosure using dynamic headspace sampling approaches. In addition, two deuterium-labeled compounds were used to assess whether they could serve as internal standards for evaluating reactive and adsorptive losses of terpenoids during in situ field measurements. Overall, this study is well-written and provide valuable insights into for designing field-based volatile measurement systems to miminize adsorptive and reactive losses. I have a few minor comments that should to be addressed in the revision.
- It is unclear how the deuterium-labeled compounds were quantified using GC-MS. A detailed description of the quantification method should be provided either in the M&M section or in the supplementary document.
- It is unclear in which lab experiments the ozone scrubbers were used. Since all experiments appears to have used dry air and if the compressed dry air was free of ozone, it is hard to understand why ozone scrubber is needed. Nonetheless, the author needs to clarify this point to avoid misunderstanding.
- While it sounds reasonable to use deuterium-labeled compounds, which are not emitted by the target research subjects, as internal standard in field measurement campaigns to account for the potential adsorptive and reactive losses of plant-derived volatiles, correction factors derived from these deuterium-labeled compounds still should to be explained with caution. This is because adsorptive losses of these deuterium-labeled compounds cannot only occur on the inner surface of the enclosure, but also on the plant surface (especially leaf surface for broad-leaf species) either by passive deposition or active uptake by plants. When the relative contribution of these two process is not known, the applicability of deuterium-labeled compounds for assessing adsorptive losses may be limited. Anyway, I suggest that the authors should address these considerations in the discussion.
- It is unclear how many replicates were used for each experiment, and what the error bars in the figure or the text refer to (standard deviation or standard error?).
Some grammatical errors should be corrected, e.g.,
Line 65, change “existed” to “exists”
Line 72 change “by using surrogates like aromatic compounds with quite different reactivity with O3.” to “by using surrogates like aromatic compounds that have quite different reactivity with O3.”
Citation: https://doi.org/10.5194/amt-2024-170-RC1 -
AC1: 'Reply on RC1', Zeng Jianqiang, 20 Feb 2025
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2024-170/amt-2024-170-AC1-supplement.pdf
-
RC2: 'Comment on amt-2024-170', Anonymous Referee #2, 12 Feb 2025
This study evaluates deuterated surrogates (α-pinene-d3 and β-caryophyllene-d2) for tracing adsorptive and reactive losses of monoterpenes (MTs) and sesquiterpenes (SQTs) in dynamic chambers. Using standard gas mixtures, it examines the effects of concentration, temperature, humidity, and O3. Adsorptive losses varied with concentration and temperature, while O3-induced losses were species-specific. The surrogates effectively corrected losses, but additional deuterated compounds are recommended for broader coverage. A strong correlation between adsorption and O3 reactivity underscores the need for careful loss correction, particularly for highly reactive SQTs, which should be measured with O3-free air when correction is unavailable. Overall, the manuscript is well written, and the results are valuable to the literature. I have some minor comments:
- Lines 82-83: Please briefly mention the size and dimensions of the chamber, as they affect VOC losses via surface adsorption.
- Section 3.1: Is there an adsorption model that can be used to quantify VOC loss? The authors may refer to He et al. (AMT, 2024) for relevant methods. (Reference: He, L., Liu, W., Li, Y., Wang, J., Kuwata, M., and Liu, Y.: Wall loss of semi-volatile organic compounds in a Teflon bag chamber for the temperature range of 262–298 K: mechanistic insight on temperature dependence, Atmos. Meas. Tech., 17, 755–764, https://doi.org/10.5194/amt-17-755-2024, 2024).
- Lines 136-137: Please add references to this sentence.
- Lines 142-148: Why do reactive VOCs exhibit greater adsorption loss? Any explanation?
- Line 181: Why not use α-pinene or β-caryophyllene directly instead of their isotopes for calibrating losses?
- Lines 191-193: Any suggestions for green leaf volatiles such as aldehydes and alcohols? How does humidity impact their losses? Please discuss.
- Line 197: Were O3 scrubbers or denuders applied before cartridge sampling?
- Lines 245-249: Sesquiterpene emissions from plants may be more sensitive to O3 stress as reported by the literature. Using O3-free air may not reflect real-world conditions. Why not apply a correction factor for sesquiterpene loss due to O3 instead?
- Table 1: It would be useful to include literature-reported reaction rates for compounds in both groups 1 and 2, which helps readers understand the extent of reaction rate differences.
- Lines 273-274: Again, would chamber-specific correction factors for different VOCs be more effective?
Citation: https://doi.org/10.5194/amt-2024-170-RC2 -
AC2: 'Reply on RC2', Zeng Jianqiang, 20 Feb 2025
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2024-170/amt-2024-170-AC2-supplement.pdf
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