Obtaining accurate non-methane hydrocarbon data for ambient air in urban areas: comparison of non-methane hydrocarbon data between indirect and direct methods

Gao, Song; Yang, Yong; Tong, Xiao; Zhang, Linyuan; Duan, Yusen; Tang, Guigang; Wang, Qiang; Lin, Changqing; Fu, Qingyan; Liu, Lipeng; Meng, Lingning

doi:https://doi.org/10.5194/amt-16-5709-2023

Articles | Volume 16, issue 23

https://doi.org/10.5194/amt-16-5709-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/amt-16-5709-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 16, issue 23

Research article

|

29 Nov 2023

Research article |

| 29 Nov 2023

Obtaining accurate non-methane hydrocarbon data for ambient air in urban areas: comparison of non-methane hydrocarbon data between indirect and direct methods

Song Gao, Yong Yang, Xiao Tong, Linyuan Zhang, Yusen Duan, Guigang Tang, Qiang Wang, Changqing Lin, Qingyan Fu, Lipeng Liu, and Lingning Meng

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Final revised paper (published on 29 Nov 2023)
Preprint (discussion started on 15 Jun 2023)

Interactive discussion

Status: closed

CC1:
'Comment on egusphere-2023-293', shuang fu, 31 Jul 2023

some questions on this study：(1) What are the main errors in indirect measurement of NMHCs?
(2) How is the measurement result improved after the method adjustment of the NMHC instrument?

Citation: https://doi.org/10.5194/egusphere-2023-293-CC1
- AC1: 'Reply on CC1', Song Gao, 16 Aug 2023
  
  (1) What are the main errors in indirect measurement of NMHCs?
  Response:
  We appreciate your questions. We found indirect NMHC measurements incorrectly characterized the low NMHC concentrations in the urban air. These measurements were hindered by the uncertain changes in the errors associated with low THC concentrations, humidity, and macroscopic substances (oxygen) in the atmosphere.
  (2) How is the measurement result improved after the method adjustment of the NMHC instrument?
  Response:
  We appreciate your questions.The error from accurate values is reduced.The average daily NMHC concentration was 162.6 ppbC, and daily NMHC values ranged from 83.8 to 309.9 ppbC. The hourly NMHCs over 300 ppbC only occurred 56 times in a total of 1035 results; meanwhile, lowest and highest NMHC values reached 42.8 and 562.3 ppbC, respectively. The majority of values ranged from 60 to 300 ppbC when the AQI was excellent. Through lab tests and field observations, we found that the results of all the indicators of instruments using the direct method were better than those using the subtraction method and the instruments using the direct method could obtain scientific data.
  
  Citation: https://doi.org/10.5194/egusphere-2023-293-AC1
RC1:
'Comment on egusphere-2023-293', Anonymous Referee #1, 14 Aug 2023

I thoroughly reviewed this manuscript. A lot of online monitoring NMHC instruments were tested, and the main problems in the experimental results were carefully analyzed by mainly focusing on the low concentration error, oxygen interference, humidity impact, and response factor. Low concentration error and humidity affected the accuracy of the results, and the response factor could sometimes not meet the theoretical value. This study optimized and conducted an experimental program for the online monitoring of the NMHC instrument using the direct method. Moreover, changing the enrichment and specially designed columns further improved the test effect.

I have listed some specific comments (see below) for this paper, and it is recommended to make minor modifications before publication.

1.Please further clarify the definition of NMHC.

2.Please make sure your ‘conclusion’ section underscore the scientific value added of your paper, and/or the applicability of your findings/results, as indicated previously.

3.The language of the paper needs careful editing and professional proofreading. Further, the entire manuscript should be written in the third person plural or singular perspective. Please avoid the use of "we" or "our".

Citation: https://doi.org/10.5194/egusphere-2023-293-RC1
- AC2: 'Reply on RC1', Song Gao, 16 Aug 2023
  
  1.Please further clarify the definition of NMHC.
  Response:
  We appreciate your question.the definition of NMHC is Non-Methane Total Hydrocarbons.
  2.Please make sure your ‘conclusion’ section underscore the scientific value added of your paper, and/or the applicability of your findings/results, as indicated previously.
  Response:
  We appreciate your question.The conclusion and applicability of findings/results in our manuscript meet the requirements.
  3.The language of the paper needs careful editing and professional proofreading. Further, the entire manuscript should be written in the third person plural or singular perspective. Please avoid the use of "we" or "our".
  Response:
  We appreciate your question.In our manuscript, we have paid attention to this point.
  
  Citation: https://doi.org/10.5194/egusphere-2023-293-AC2
RC2:
'Comment on egusphere-2023-293', Anonymous Referee #2, 15 Aug 2023

I agree the the manuscript should be accepted as is.

Citation: https://doi.org/10.5194/egusphere-2023-293-RC2
- AC3: 'Reply on RC2', Song Gao, 16 Aug 2023
  
  I agree the the manuscript should be accepted as is.
  Response:
  We thank you for your recognition of our manuscript.
  
  Citation: https://doi.org/10.5194/egusphere-2023-293-AC3

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Song Gao on behalf of the Authors (17 Aug 2023) Author's response

EF by Polina Shvedko (21 Aug 2023) Manuscript Author's tracked changes

ED: Publish as is (16 Sep 2023) by Keding Lu

AR by Song Gao on behalf of the Authors (19 Sep 2023) Manuscript

Short summary

We optimized and conducted an experimental program for the real-time monitoring of non-methane hydrocarbon instruments using the direct method. Changing the enrichment and specially designed columns further improved the test effect. The results correct the measurement errors that have prevailed for many years and can lay a foundation for the evaluation of volatile organic compounds in the regional ambient air and provide direction for the measurement of low-concentration ambient air pollutants.