the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 05 Mar 2025
Carbonyl compounds from typical combustion sources: emission characteristics, influencing factors, and their contribution to ozone formation
Abstract. Combustion sources are the important primary emission sources of carbonyl compounds (CCs), yet the emission factors (EFs) and influencing factors for CCs in different sources remain unclear. The emission characteristics, influencing factors, and ozone formation potentials (OFPs) of CCs from four combustion sources, including biomass burning (BB), residential coal combustion (RCC), on-road sources, and agricultural machinery (AM), were investigated by field measurements. Results indicate that the EFCCs from four combustion sources exhibit significant differences. Specifically, the EFs from BB (1968.2±661.2 mg/kg) are significantly higher than other sources, being an order of magnitude greater than the on-road sources (117.8±78.3~576.3±47.4 mg/kg). Fuel types is key factors affecting the CCs components. BB primarily emit formaldehyde and acetaldehyde (F+A), accounting for 80 % of CCs, whereas RCC exhibits a higher proportion of aromatic aldehydes and acetone (26.0 %). The addition of ethanol in on-road sources and biodiesel in AM effectively promotes the formation of acetaldehyde (67.9 %) and unsaturated aldehydes (20.4 %), respectively. The formation of CCs in solid and liquid fuel sources is more sensitive to combustion temperature and emission standards, respectively. Higher combustion temperature and stricter emission standards can reduce CCs emissions by 94.6 % in solid fuels and by 61.3 % in liquid fuel, respectively. High-temperature promotes small molecules like F+A tend to cyclize, supplying ample precursors for the formation of acetone and aromatic aldehydes. More attention should be paid to the OFPs of CCs from BB and AM to allevite the oxidizing capacity of regional atmospheres.
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Status: open (until 16 Apr 2025)
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RC1: 'Comment on egusphere-2025-131', Anonymous Referee #1, 14 Mar 2025
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This manuscript focused on carbonyl compounds emitted by four types of combustion sources, including biomass burning, residential coal combustion, on-road vehicles and non-road mobile machineries. The emission factors were carefully determined and their influencing factors were comprehensively discussed. I think this manuscript could be considered for publication in ACP, after minor revisions. My detailed comments are given below.
Major point. Section 2.1, softwood and hardwood should be clearly distinguished. Section 3.1, please clarify whether the emission characteristics were comparable between softwood and hardwood. If not, please give possible explanations.
Minor points.
1. Abstract, re-write the first sentence as “Fuel combustions are important primary sources of carbonyl compounds (CCs)……”
2. Abstract, line 30, suggest removing the “tend”.
3. I noticed that “EFccs” appeared only once. Remove this abbreviation or use it to replace “EFs of CCs” throughout the manuscript.
4. Some abbreviations were repeatedly defined. For example, CCs was defined twice in Page 2; EFs was defined again in Page 5.
5. Grammar mistakes like “Fuel types is key factors…(Page 1)” and “Fuel types determines the composition of…(Page 15)” should be avoided.
6. Equations in Page 5, suggest using hyphens, which could be clearly distinguished from the minus signs, for the subscripts (e.g., c-fuel).
7. Page 7. Suggest briefly explaining the “bell-shaped distribution theory”.Citation: https://doi.org/10.5194/egusphere-2025-131-RC1 -
AC1: 'Reply on RC1', Yingjun Chen, 17 Mar 2025
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Dear Reviewer,
We sincerely appreciate your thorough review and constructive comments on our manuscript titled "Emission Characteristics and Influencing Factors of Carbonyl Compounds from Four Typical Combustion Sources." We are grateful for your recognition of the manuscript's potential for publication in ACP and for your detailed suggestions, which have significantly improved the quality of our work. Below, we provide a point-by-point response to your comments and outline the revisions we have made accordingly.
Major Point:
1. Distinction between softwood and hardwood (Section 2.1 and Section 3.1):
We sincerely apologize for the oversight in not clearly distinguishing between softwood and hardwood in the original manuscript. In the revised version, we have explicitly differentiated these two fuel types in Section 2.1. Additionally, in Section 3.1, we have added a detailed comparison of the emission characteristics between softwood and hardwood. Our analysis reveals that softwood (e.g., pine) tends to emit higher concentrations of carbonyl compounds, particularly small-molecule carbonyl compounds such as formaldehyde and acetaldehyde, which is likely attributed to differences in lignin content and combustion efficiency. This finding has been discussed in the revised manuscript, along with potential explanations for the observed variations.
Minor Points:
2. Abstract, first sentence:
As suggested, we have rephrased the first sentence of the Abstract to: “Fuel combustions are important primary sources of carbonyl compounds (CCs)…” This revision improves the clarity and precision of the statement.
3. Abstract, line 30:
The word “tend” has been removed as recommended. The revised sentence now reads: “High-temperature promotes small molecules like F+A to cyclize, supplying ample precursors for the formation of acetone and aromatic aldehyde.”
4. Use of “EFCCs” abbreviation:
We have carefully reviewed the manuscript and replaced all instances of “EFs of CCs” with “EFCCs” to ensure consistency. This change has been applied throughout the text.
5. Repeated definitions of abbreviations:
We apologize for the redundancy in defining abbreviations. In the revised manuscript, we have ensured that each abbreviation (e.g., CCs, EFs) is defined only once upon its first appearance.
6. Grammar mistakes:
We sincerely apologize for the grammatical errors in the original manuscript. The following corrections have been made:
“Fuel types is key factors…” has been corrected to “Fuel type is a key factor…”
“Fuel types determines the composition of…” has been corrected to “Fuel type determines the composition of…”
All other instances of subject-verb disagreement have been carefully reviewed and corrected.
7. Equations in Page 5:
Thank you for pointing out the inconsistency in the use of hyphens and minus signs in the equations. We have revised the equations to use hyphens for subscripts (e.g., c-fuel) and minus signs for mathematical operations, ensuring clarity and consistency.
8. Explanation of “bell-shaped distribution theory” (Page 7):
We have added a brief explanation of the “bell-shaped distribution theory” in the revised manuscript. Specifically, we describe it as a theoretical framework used to explain the relationship between the volatile content of residential coal and its emission characteristics, where emissions peak at intermediate volatile content and decrease at both very high and very low volatile content levels. This addition provides better context for readers unfamiliar with the concept.
Additional Revisions:
In addition to addressing your specific comments, we have conducted a thorough proofreading of the manuscript to correct any remaining grammatical errors, improve sentence structure, and ensure consistency in terminology and formatting. We have also double-checked all abbreviations, equations, and references to ensure accuracy.
Once again, we deeply appreciate your time and effort in reviewing our manuscript. Your insightful comments have greatly enhanced the clarity, rigor, and overall quality of our work. We hope that the revised manuscript now meets the high standards of ACP and look forward to your feedback.
Sincerely,
Yanjie Lu
On behalf of all authors
Citation: https://doi.org/10.5194/egusphere-2025-131-AC1
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AC1: 'Reply on RC1', Yingjun Chen, 17 Mar 2025
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RC2: 'Comment on egusphere-2025-131', Anonymous Referee #2, 17 Mar 2025
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This manuscript presents a comprehensive and in-depth study on the emission characteristics and influencing factors of carbonyl compounds (CCs) from various typical combustion sources. It provides the latest data for emission inventories and offers a scientific basis for targeted emission reduction strategies. This manuscript will make a significant contribution to the control and management of air pollution. However, the current manuscript contains several minor issues that require revision prior to consideration for publication in Atmospheric Chemistry and Physics.
Minor comments:
1. The abstract should be revised to better articulate the scientific innovation and applied value of this study, specifically by explicitly stating its contributions to optimizing combustion systems, guiding emission control policies, and enhancing atmospheric chemistry modeling frameworks.2. The conclusion section should include specific estimates of the emission reduction effects of the proposed measures on atmospheric oxidizing capacity. For example, the impact of increasing combustion temperature and upgrading emission standards on ozone (O₃) formation should be quantified.
3. Spelling errors. In line 32 of the abstract, "allevite" should be corrected to "alleviate".
4. Terms such as “EFCCs” should be defined upon their first appearance, and consistent usage should be maintained throughout the manuscript. For example, “EFCCs” and “EFs of CCs” should be standardized. Additionally, some abbreviations need to be redefined to avoid confusion with commonly used abbreviations, such as AA and OA.
5. Some sentences are lengthy and complex. Simplifying sentence structures can improve readability. For instance, the second paragraph of the introduction (line 49) could be broken into multiple sentences, and it’s necessary to add the following reference in revised manuscript.
Emission of Intermediate Volatile Organic Compounds from Animal Dung and Coal Combustion and Its Contribution to Secondary Organic Aerosol Formation in Qinghai-Tibet Plateau, China. Environmental Science & Technology 2024 58 (25), 11118-11127.6. Line 105: For biomass samples, the selection of 2g is difficult. Besides, the combustion process is very fast. How can the author ensure the accuracy of sampling throughout the entire combustion process? the following are some references related to experiment process that can be cited:
Examination of long-time aging process on volatile organic compounds emitted from solid fuel combustion in a rural area of China. Chemosphere 333 (2023) 138957.7. Ensure that the font size in all figures and tables is consistent to present a more organized and visually appealing layout. For example, the legend font size in Figure 1a is slightly larger than in the other three subfigures.
8. The manuscript should include (1) uncertainty quantification analyses of ozone formation potential across diverse CCS emission sources, and (2) a schematic diagram of the sampling system in Section 2.1 to enhance methodological transparency.
9. The figures should be replaced with higher resolution versions to ensure graphical clarity essential for proper interpretation of the experimental data.
Citation: https://doi.org/10.5194/egusphere-2025-131-RC2
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