the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Measurement report: characterization and sources of the ambient secondary organic carbon in a Chinese megacity over five years from 2016 to 2020
- 1Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
- 2Shanghai Environmental Monitoring Center, Shanghai, China
- 3School of Physics, Ryan Institute's Centre for Climate & Air Pollution Studies, and Marine Renewable Energy Ireland, National University of Ireland Galway, University Road, Galway, H91 CF50, Ireland
- 4State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China
- 5Zhejiang Tianlan Environmental Protection Technology Co., Ltd., Hangzhou 311202, China
- 6Department of Environmental Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
- 7State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
- 8Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
- 1Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
- 2Shanghai Environmental Monitoring Center, Shanghai, China
- 3School of Physics, Ryan Institute's Centre for Climate & Air Pollution Studies, and Marine Renewable Energy Ireland, National University of Ireland Galway, University Road, Galway, H91 CF50, Ireland
- 4State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China
- 5Zhejiang Tianlan Environmental Protection Technology Co., Ltd., Hangzhou 311202, China
- 6Department of Environmental Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
- 7State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
- 8Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Abstract. To investigate impact factors and source area of secondary organic aerosols in the Yangtze River Delta (YRD) region, a world-class urban agglomeration in China, long-term measurements of organic carbon (OC) and elementary carbon (EC) in particulate matter of less than 2.5 μm (PM2.5) with hourly time resolution were conducted at a regional site in Shanghai from 2016 to 2020. Based on the five-year measurements, the interannual, monthly, seasonal, and diurnal variations in OC and EC, as well as OC subtypes, i.e., secondary OC (SOC) and primary OC (POC), apportioned by the novel statistical model of the minimum R2 method, and the formation pathways of SOC, are presented. By examining the relationship between SOC and temperature, as well as relative humidity (RH), we show that SOC formation is greatly enhanced at high temperatures (>30 °C), while it is inversely correlated with RH. In particular, we show that the photochemical formation of SOC is the major formation pathway even in winter when solar radiation was supposedly less intense than in summer, which is different from that in north China plain where aqueous phase chemistry is found to be an important SOC formation pathway. Moreover, increased SOC concentrations are also found to be associated with high wind speed (>5 m s−1) in winter, which is increased by 29.1 % (2.62 μg m−3) when compared to that during lower winds, suggesting regional sources of SOC in winter. By analyzing the potential source regions using the concentration weighted trajectory (CWT), the geographic regions of SOC are found to be mainly associated with transport from outside Shanghai (SOC > 3.5 μg m−3) including central and southern Anhui, Zhejiang, and Fujian. The results from this study provide critical information about the long-term trend of carbonaceous aerosol, in particular SOC, in one of the largest megacities in the world and are helpful to develop pollution control measures from a long-term planning perspective.
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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.
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Preprint
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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
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Supplement
(1814 KB) - BibTeX
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Journal article(s) based on this preprint
Meng Wang et al.
Interactive discussion
Status: closed
-
RC1: 'Comment on acp-2022-289', Anonymous Referee #1, 18 Jun 2022
Wang et al. reported a five-year data containing organic carbon and elementary carbon in the Shanghai, one of the biggest cities in the world. The measurement of such long-term is very valuable for policy evaluation and numerical modelling. The manuscript is well written although subjected to a few linguistic typos. The data were presented in a concise but detailed way and the main conclusion from the manuscript is clear that secondary organic aerosol (SOA) is becoming more and more important for mitigating air pollution. I believe the manuscript is suitable for publication in ACP from addressing the following issues, most of them are minor:
- The “ambient” in the title can be removed.
- The introduction is a bit lengthy; I understand the carbon aerosol is a large topic and there are many existing knowledge, but you don’t need to introduce them all, e.g. what’s the point of citing all the carbonaceous aerosol studies from line 63 to line 67.
- Line 48. You mention carbonate carbon only once, what’s the point using an abbreviation
- Line 55. Termed as
- Delete “in issues varying”
- Line 68 what is the relationship between this nationwide measurement with your study?
- Line 73 you don’t need a reference to introduce Shanghai?
- Line 96 in PM2.5, not fraction.
- Section 2 in Figure S1, please add a scale on the map.
- Section 3 as far as I understand, the concentrations is not normally distributed, the data should be reported in median (and 25th to 75th ranges)
- Line 172 what is the possible cause of the abrupt change of POC in 2020?
- Line 213 why is the weekend -weekday pattern important?
- The manuscript was focused on secondary organic aerosol, but a large fraction in 3.1 was given to primary organic aerosol.
- Section 3.2.1 It is intriguing to see the SOC increased with temperature, the authors represent a detailed analysis on the effect of temperature on SOC concentrations, but it is unclear how temperature impacts SOC. I understand that temperature can boost biogenic VOC in boreal area that act as SOC precursors, but in mega city in Shanghai it is uncommon. A possible reason should at least be given.
- Line 311. “The concentration of Ox”
- Line 392. Does this suggest that SOC observed in Shanghai is mainly originated from regional transport?
- AC1: 'Reply on RC1', Meng Wang, 30 Aug 2022
-
RC2: 'Comment on acp-2022-289', Anonymous Referee #2, 09 Jul 2022
The manuscript entitled "Measurement report: characterization and sources of the ambient secondary organic carbon in a Chinese megacity over five years from 2016 to 2020" conducted a long-term field campaign at a regional site in the YRD region from 2016 to 2020 and aimed to investigate the characteristics of carbonous aerosol pollution and their seasonal and diurnal variations, as well as the relationship between the meteorological factors and carbonaceous aerosol concentrations. This study enhanced the understanding of the variation and sources of SOC in the PM2.5 fraction, and was in favor of evaluation of the effectiveness of the current air pollution control policies. The manuscript is overall well organized, and can be read easily. I broadly agree with the discussions and findings of this manuscript. I therefore recommend a minor revision of this manuscript before final publication in ACP.
- In the conclusion, it is difficult for me to find research findings with strong regularity or regional characteristics of the Yangtze River Delta. Therefore, it is suggested to condense the conclusion.
- In 3.2.3, The discussion on the formation of photochemistry should have become one of the highlights of the paper, but unfortunately, the reviewer found that the author basically stayed at the level of the discussion on the correlation between ox and SOC, and lacked in-depth analysis of radiation intensity and liquid phase processes, suggesting further in-depth discussion.
- AC2: 'Reply on RC2', Meng Wang, 30 Aug 2022
Peer review completion
Interactive discussion
Status: closed
-
RC1: 'Comment on acp-2022-289', Anonymous Referee #1, 18 Jun 2022
Wang et al. reported a five-year data containing organic carbon and elementary carbon in the Shanghai, one of the biggest cities in the world. The measurement of such long-term is very valuable for policy evaluation and numerical modelling. The manuscript is well written although subjected to a few linguistic typos. The data were presented in a concise but detailed way and the main conclusion from the manuscript is clear that secondary organic aerosol (SOA) is becoming more and more important for mitigating air pollution. I believe the manuscript is suitable for publication in ACP from addressing the following issues, most of them are minor:
- The “ambient” in the title can be removed.
- The introduction is a bit lengthy; I understand the carbon aerosol is a large topic and there are many existing knowledge, but you don’t need to introduce them all, e.g. what’s the point of citing all the carbonaceous aerosol studies from line 63 to line 67.
- Line 48. You mention carbonate carbon only once, what’s the point using an abbreviation
- Line 55. Termed as
- Delete “in issues varying”
- Line 68 what is the relationship between this nationwide measurement with your study?
- Line 73 you don’t need a reference to introduce Shanghai?
- Line 96 in PM2.5, not fraction.
- Section 2 in Figure S1, please add a scale on the map.
- Section 3 as far as I understand, the concentrations is not normally distributed, the data should be reported in median (and 25th to 75th ranges)
- Line 172 what is the possible cause of the abrupt change of POC in 2020?
- Line 213 why is the weekend -weekday pattern important?
- The manuscript was focused on secondary organic aerosol, but a large fraction in 3.1 was given to primary organic aerosol.
- Section 3.2.1 It is intriguing to see the SOC increased with temperature, the authors represent a detailed analysis on the effect of temperature on SOC concentrations, but it is unclear how temperature impacts SOC. I understand that temperature can boost biogenic VOC in boreal area that act as SOC precursors, but in mega city in Shanghai it is uncommon. A possible reason should at least be given.
- Line 311. “The concentration of Ox”
- Line 392. Does this suggest that SOC observed in Shanghai is mainly originated from regional transport?
- AC1: 'Reply on RC1', Meng Wang, 30 Aug 2022
-
RC2: 'Comment on acp-2022-289', Anonymous Referee #2, 09 Jul 2022
The manuscript entitled "Measurement report: characterization and sources of the ambient secondary organic carbon in a Chinese megacity over five years from 2016 to 2020" conducted a long-term field campaign at a regional site in the YRD region from 2016 to 2020 and aimed to investigate the characteristics of carbonous aerosol pollution and their seasonal and diurnal variations, as well as the relationship between the meteorological factors and carbonaceous aerosol concentrations. This study enhanced the understanding of the variation and sources of SOC in the PM2.5 fraction, and was in favor of evaluation of the effectiveness of the current air pollution control policies. The manuscript is overall well organized, and can be read easily. I broadly agree with the discussions and findings of this manuscript. I therefore recommend a minor revision of this manuscript before final publication in ACP.
- In the conclusion, it is difficult for me to find research findings with strong regularity or regional characteristics of the Yangtze River Delta. Therefore, it is suggested to condense the conclusion.
- In 3.2.3, The discussion on the formation of photochemistry should have become one of the highlights of the paper, but unfortunately, the reviewer found that the author basically stayed at the level of the discussion on the correlation between ox and SOC, and lacked in-depth analysis of radiation intensity and liquid phase processes, suggesting further in-depth discussion.
- AC2: 'Reply on RC2', Meng Wang, 30 Aug 2022
Peer review completion
Journal article(s) based on this preprint
Meng Wang et al.
Data sets
Measurement report: characterization and sources of the ambient secondary organic carbon in a Chinese megacity over five years from 2016 to 2020 Wang, M., Duan, Y., Xu, W., Wang, Q., Zhang, Z., Yuan, Q., Li, X., Han, S., Tong, H., Huo, J., Chen, J., Gao, S., Wu, Z., Cui, L., Huang, Y., Xiu, G., Cao, J., Fu, Q., and Lee, S.-c. https://doi.org/10.5281/zenodo.6473085
Meng Wang et al.
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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.
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